Ornl 3936 by The "E" Generation

ORTSL-3936

Contract No. W-7405-eng-26

MOLTED-SALT BEACTOR PROGRAM. SEl4ImWAL PROGFESS REPORT

For Period Ending February 28, 1966 R. B. Briggs, Progr<aunDirector

JUNE 1 9 6 6

OAK RIDGE NATIONAL LABORATORY

Oak Ridge, Tennessee operated by UNION CARBIDE CORPORATION for the

3 YYSb 0 3 8 2 6 1 0 8

............................................................ I~l~RODUCTION .......................................................

Y . . . .

Part 1

1. K5lU SO.I.P.

v i 3. I

MS17.E OPERATIONS AND COITSTRUCTION. ENGITWRLTNC) .4NALYSIS. M i 1 3 COWO?LElIT DEVI!XOPJmi'L'

................................................

..........................................

Chronological t . o c A Analysis of ~ ~ e r i m e n t s R e a c t i v i t y Balance Power C a l i b r a t i o n F l u x Measvccemerits MSRi3 Dynamic T e s t s D e s c r i p t i o n of Dynamic T e s t s Frequency Response Tests Implementation of Pseudorwidcjin Zinary T e s t s Analysis Proce..es

........................................ ......................................... .......................................... .......................................... ............................................. ............................... ................................... ................ ........................................ Results .................................................... Temperature Response T e s t .................................. S y s t e m Per%o.ance ............................................ O f f - G a s ~ y s trne............................................. Salt-Pump O i l Systems ...................................... T r e a t e d Cooling-'Water System............................... Secondary Containment ...................................... S h i e l d i n g .................................................. Component Performance .......................................... R a d i a t o r ................................................... Other Corn~onents........................................... I n s p e c t i o n of t h e Fuel P q ................................ Heat Treatment of Reactor Vessel ........................... S t r e s s Analysis of Reactor Piping and Nozzles .............. I n s t r u m e n t a t i o n and Controls ................................... .;enera1 .................................................... S a f e t y Instmuneutation ..................................... Wide-Range Counting Channels ............................... Nuclear Instrument P e n e t r a t i o n ............................. BF3 Confidence I n s t r u m e n t a t i o n ............................. Personnel Monitoring System ................................ Control Inst..ntation .................................... Operating Experience - Process and Nuclear Instruments ..... Data System ................................................ MSRE Training Simulators ................................... Docwnen.t;ation ..............................................

7 LO

12 12

1-3

15 16

1.7

18 22 23 23

27 28

34 34 34 36

40 41 41

41 42 42

4.4 45 46 47

49 50 51

.......................................... Freeze Valves .................................................. Control Roas ................................................... Control Rod Drive Units ........................................ Radiator Doors ................................................. Radiator Heater E l e c t r i c a l - I n s i l l a t i o n F a i l u r e .................. S a m ~ l e r - E n r i c h e ............................................... r CoolaIit S a l t S ~ ~ l........................................... e r Examination of Components Prom t h e MSlRE Off-Gas System ......... C a p i l l a r y Flow Z e s t r i c t o r FE 521 ........................... Check Valve CV 533 ......................................... Charcoal Bed I n l e t Valve HV 621 ............................ Line 522 Pressure C o n t r o l Valve PCV 522 .................... Line FilLe r 522 ............................................ Flow Test on t h e JGM F i l t e r from Line 522 ................. Fuel Processing System Sampler ................................. Off-Gas Sampler ................................................ Xenon bligration i n t h e WRE .................................... Remote ..intenance ............................................. P r a c t i c e Before Operation .................................. b’Ia,intenance of Radioactive S y s t e m ......................... Pump Developmen-t ............................................... MSRZ Puml?s ................................................. Other Mol-ten-Salt h m p s .................................... Instrument Develo~inent......................................... Ultrasonic Single-Point Molten-Salt Level Probe ............ High-Temperature TJaK-Fil.led Differen-bial-Pyessure Transmitter .............................................. F l o a t -Type Molten-Salt Level Transmitter ................... Conductivity-Type Stngle-Point Molben-Salt k v e L Probe ..... Single-Point Temperabure fUam Switches .................... H e l i u i i Control Valve T r i m Replacement ...................... Thermocouple Deve1opmn.t and Testing ....................... Terrperatiire Scanner ........................................ 3 . MSRF: REXCTOlI ANALYSIS ..........................................

2 . COMPONENT D E ~ L O P ~ N T

...............

Tkzst-Squares Formula f o r Control Rod R e a c t i v i t y S p a t i a l Distri-bution of 135Xe Poisonir-g i n MSRE Graphite

.......

..................................................... Dynamic Corrosion Studies ...................................... MSRE Materj.al Surveillance T e s t s ............................... Reactor S u r v e i l l a n c e Specimens ............................. S u r v e i l l a n c e Control Specirnens ............................. Bot - C e l l Metallographic ?Zknmj.na-t;ion of Hastelloy N from Experiment iWR-47-6 for Evidence o f N i t r i d i n g ................ METALL~HGY

53 53 53

54 54

57 58 59 60 60 60 60 62

64 65 65 67 69 70 72

72 74 74. 75 77

7’7 77

78 78 79 79

82 82 87

95 95 96 96

99 100

......................................... quqd a p A a a 8 Tand ........................................ q U q - 6 Lama xoq3'"ea-g qso3 p q . T d q - J ............................ SuzaqsKS m a q g aaq'"eqqs3 pu,e a8u.eq3q q-eag ........................................... 8 r q s s a ~ oTang ~~ ............................................. xoqasa~ ..................................................u8TsaaqaaysMoT,: .............................................. u2Tsaa q.uz1-i-jg g a i ....*......................................c-

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ZZT

......................................................

xZJ;S:T'xa-I *G D

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.................... ........................................ .......................................... .................................... ................ 7 . MOLTEN-WET i U C T O R PROCESSING STUDIES......................... Semicontinuous D i s t i l l a t i o n .................................... F u e l Reconsti.i;ut;ion............................................ Continuous FLuorination of a Molten S a l t ....................... Chromium F l u o r i d e Trapping ..................................... Design and Evaluation Study .................................... D e s c r i p t i o n of Fuel Process .................................... Description of F e r t i l e Process ............................. Waste Treatment ............................................ O f f - G a s Trea.tment .......................................... Summary of Capital a n d Operating Costs ..................... Processing Cost ............................................ Nuclear Performance and Fuel Cycle Analyses Analysis P r o c e d ~ e s Basic Assumptions Nuclear Design Analysis Power Cost and.Fue1 U t i l i z a t i o n C h a r a c t e r i s t i c s

186 186 1-86 189 191 1.93

194 1.99 202 202 203 204 208 208 209 209 210

vii

P a r t 1. WIIF Operations and ConstructionL Enairleering Analvsi s and Cornuoiient Bvelonrneri-t

IVLSH? Operations

Preparations f o r power o p e r a t i o n were completed, a n d t h e was operated a t riuclear powers up t o 1 Mw b e f o r e t h e system w a s shut down t o r e p l a c e a space-cooler motor and t o r e l i e v e p h g g i n g p r o b l e m i n t h e o f f gas system. The power p r e p a r a t i o n s i n c h c i e d some system modification:; shown t o

be r e q u i r e d by o p e r a t i n g experience and by c o n t i m i n g development and

a n a l y s i s work. Iiernote nialnteiiance teckniques were t r i e d and evaluated, soriie special. t e s t s .were performed, t h e o p e r a t o r s were t r a i n e d and q u a l i f i e d f o r power operation, and t h e secondary containment w a s s e a l e d arid s h o w n t o have an acceptably Low l e a k rate.

The nuclear performance of the system ai; a l l powers up t o I Mw w a s highl.y satisfac-Lory. Reproducible r e a c t i v i t y behavior and. a I.ack of s i g n i f i c a n t cross con-LmLination. between t h e fuel. and f l u s h s a l t s were demonstrated. Dynamics t e s t s at power showed -I;ha,t t h e m a e t o r has a s l i g h t l y wider margin of s t a b i l i t y t h a n had.been p r e d i c t e d from calculatioris Preliminary r e s i ~ l t s.indicate that; xenon poisoning may be lower th.an was a n t i c i p a t e d . a

'ilie performance of most of t h e equipnent :gas s a t i s f a c t o r y , b u t s u . b s t a n t i a 1 o p e r a t i o n a l d i f f i c u l t y w a s caused by plugging or" very small openings i n o f f - gas :;ys.Lem coniponelrlts by organic material This probI.em was e x t e n s i v e l y i n v e s t i g a t e d af-i;er t h e s!mtdowri fro:m 1 M V T ~ Other, l e s s s e r i o u s problems included t h e f r e a k f a i l u r e of ail e1eei;:r.j.c motor i n s i d e the secondary contairurierit, a c t i v a t i o n of t h e c o r r o s i o n i n h i b i t o r i n the t r e a t e d cooling w a t e r , a i r entrainment i n t h e cool-ing water, and exc e s s i v e r a d i a t i o n levels i n a few remote a r e a s . SoJ.utioris have been developed for a l l t h e problems except t h e off-gas plugging, which i s s t i l l ixnder study.

Formal design of t h e instrumentation and con-Lrolssystems for -the Ad.ditions and modifications a r e now being m a d e as needed t o provide a d d i t i o n a l p r o t e c t i o n , improve performance, o r pr'ovfide more information f o r t h e o p e r a t o r s .

IvL?R%: Was completed.

The adciltion of a low-level. UF3 counting climmel with c o n t r o l fun(:t i o n s , t h e a d d i t i o n of cadmium s h i e l d i n g i n the neutron iiistruxient pentt r a t i o n , and changing :reactor period inte:rlock t r i p poirlt:; were r e q u i r e d t o obtain s a t i s f a c t o r y performance of the nuelear Instrimienta.i;iori system. The remtiining changes were mostly of secondary fniportance Some spouad.ic

viii

d i f f i c u l t i e s were experienced with individual. hardware items such as ati" and helium vaJ:ves and e l e c t r o n i c switches. Mas% of t h e work done on t h e inst:cixnent system can be c h a r a c t e r i z e d as debugging t h e original- instal.lation. Tihe data-logger-computer w a s put i n t o o p e r a t i o n i n con jxnction with A.lt,hough t h e performance has not been up t o expectations, it i s proving u s e f u l t o t h e o p e r a t i o n of t h e r e a c t o r experiment. A power l e v e l simulator w a s assembled, and it operated s a t i s f a c t o r i l y for t h e t r a i n i n g of operators. the r e a c t o r .

Component -Development

The "fast thaw" requirement w a s eliminated i n a l l f r e e z e valves except f o r t h o s e which c o n t r o l t h e emergency d r a i n of tht. r e a c t o r and of t h e coolant system. The o p e r a t i o n of a l l t h e valves which might c o n t a i n s i i C f j c i e n t r a d i o a c t i v i t y i n t h p s a l t t o produce r a d i o l y t i c f l u o r i n e a t low temperature a r e now operated above CtOO'F, which i s above t h e t h r e s h o l d for flu.orine r e l e a s e . The braided wire sheath cover f o r t h e convoluted hose of c o n t r o l rod No. 3 w a s found t o be severely t o r n about 2 f t bel.ow i . t s upper end. The cause w a s t r a c e d t o a j a m l e d . r o l l e r i n t h e upper bend o f t h e control. r o d thirtible. The r o l l e r was replaced, and t h e upper rod sheath w a s repaj-red. There has been no f u r t h e r d i f f i c u l t y a f t e r s e v e r a l months of operation. Control rod drive unit No. 3 w a s replaced because of a s h i f t i n t h e remote p o s i t i o n i n d i c a t i o n and because of a tendency f o r t h e lower l i m i t srqitch t o s t i c k . The s h i f t of the i n d i c a t e d p o s i t i o n w a s eliminated by removing t h e excess s l a c k i n t h e chain, which had allowed t h e chain to s1.j.p over t h e sprocket. The s t i c k i n g lower l i m i t switch is being cured by r e p l a c i n g t h e r e t u r n s p r i n g with a s t r o n g e r one. Modifications were made t o the r a d i a t o r door guide t r a c k s and lock mechanisms t o allow f o r thermal d i s t o r t i o n , found a f t e r -the i n i t i a l . opera t i o n of t h e r a d i a t o r doors a t temperature. A l t e r a t i o n s were made t o t h e l i m i t switch system t o prevent a damaging o v e r t r a v e l of Lhe door i n t h e upper end of t h e t r a v e l . A "loss-of-tension" device w a s designed vhich w i l l s t o p t h e r a d i a t o r door d r i v e u n i t should t h e door support; c a b l e s show any s l a c k as t h e door i s being lowered. This arrangement i s intended t o prevent damage -Lo 'die support cable i f t h e r a d i a t o r door jams, as w e l l as t o lindicate a m a l function.

F a i l u r e of the i n s u l a t i o n om t h e e l e c t r i c a l l e a d s t o t h e r a d i a t o r h e a t e r s was t r a c e d t o excessive h e a t leakage i n t o t h e area immediately above t h e r a d i a t o r . Charges were made Lo reduce t h e temperature i n t h i s area, and e l e c t r i c a l i n s u l a t i o n with a higher temperature r a t i n g vas i n stalled.

S e v e r a l changes were made t o t h e sampler-enricher t o improve t h e o p e r a t i o n and s a f e t y of t h i s system. Among t h e s e were t h e changes made t o t h e i n t e r l o c k c i r c u i t , which r e q u i r e t h a t a d d i t i o n a l b a r r i e r s be p r e s e n t during c e r t a i n c r i t i c a l o p e r a t i o n s , t h e r e b y a s s u r i n g double corit a r m e n t a t a l l times. Forty samples were t a k e n during runs 4 and 5, n i n e of which were l a r g e 50-g samples f o r oxygen a n a l y s i s . These l a g e r sanples caused some d i f f i c u l t y u n t i l t h e capsule design w a s a l t e r e d s l i g h t l y t o make it hang s t r a i g h t e r . Gae of t h e o p e r a t i o n a l v a l v e s developed a 20-cc/min ti-. ~ 1 t u . ml e a k a c r o s s one of t h e two s e a l i n g s u r f a c e s of t h e g a t e . Since t h i s i s one of two v a l v e s i n t h e line and t h e l e a k i s c l e a n b u f f e r gas, t h e valve w8s n o t replaced.

During t h e sane p e r i o d t e n sarapI.es were rerrioved from the c o o l a n t system, two of which 'were t h e l a r g e r 50-g samples. The f i r s t sample extended shutdown had a b l a c k film on it, whic..h w a s i d e n t i t a k e n a f t e r af i e d . as decomposed oil. Although t h e r e w a s o i l i n t h e g e n e r a l a r e a the e x a c t so-cu'ce w a s not e s t a b l i s h e d . No films were found on subsequent sctrr1ples. The design and i n s t a l l a t i o n of t h e f u e l processing system sampler i s proceeding.

A system i s being designed t o perrnit arzalysis of t h e react,or o f f - g a s strecur?. It will c o n t a i n :

1. 2. 3.

a thermal c o n d u c t i v t t y c e l l f o r on-line i n d i c a t i o n of t h e gross cont a m i n a t level, R

c h r o m t o g r a p h f o r q u a n t i t a t i v e determination of contaninant,

a r e f r i g e r a t e d molecular s i e v e t r a p f o r i s o l a t i o n of a e o a c e n t r a t e d smi1pI.e f o r t r a n s f e r t o a h o t l a b o r a t o r y fc;r i s o t o p i c a n a l y s i s .

Estimates of t h e '"Xe poison f r a c t i o n f o r the IvEE: were computed as a f u n c t i o n of s e v e r a l paranie-ters. A t 10 i'&r t h e r e s u l t s i n d i c a t e t h a t the poison f r a c t i o n i s 1.6%. It was found t h a t t h e mass transfer coeff i c i e r r t from t h e salt t o t h e g r a p h i t e i s c o n t r o l f i n g t h e tr.. ct.tisfer and t h a t t h e p r o p e r t i e s of t h e g r a p h i t e a r e not; important.

The remote maintenance group gained more experience w i t h t h e reac-Lor components during t h e p e r i o d p r i o r t o power. o p e r a t i o n . Ariong t h e s e Were removing a i c l r e p l a c i n g t h e pimp r o t a r y element and r e p l a c i n g the g r a p h i t e sampler assembly. A f t e r a s h o r t p e r i o d of power operat?.on s e v e r a l operations were performed, u s i n g remote maintenance techniques, on a, mildlyr adi oac t i v e system.

The WRE pump t e s t f a c i l i - t y w a s modified, and t h e prototype pmip was operated f o r periods of 165 and 166 hr a t 1.200’F to provide shaked o m of t h e spa.re f u e l pump i m p e l l e r and t h e spare coolant pump d r i v e mo-Lor. The spare r o t a r y element f o r t h e fue7. pump w a s modified t o provide p o s i t i v e seali-ng a g a i n s t o i l lealtage from t h e s h a f t lower s e a l c a t c h b a s i n i n t o .the system p a s t -tile o u t s i d e of t h e s h i e l d plug. The d r i v e motor containriient v e s s e l was redesigned, and t h e new design w i l l be used f o r t h e f i f t h d r i v e motor v e s s e l . Modified. e j e c t o r s were i n s t a l l e d on t h e l u b r i c a t i o n systems f o r bhe MSRE s a l t pumps, and t h e lubricatrion pump endurance t e s t w a s continued. ‘The MIC-2 f u e l pump t a n k design w a s complkted and i s being reviewed. The PK-P m o l t e n - s a l t pump continues on endurance o p e r a t i o n and has operated for 22,622 hr. Toe pump c o n t a i n i n g t h e m o l t e n - s a l t b e a r i n g w a s placed i n operation, b u t t h e b e a r i n g s e i z e d a f t e r 1 h r of o p e r a t i o n . g f f o r t s t o improve t h e s t a b i l i t y o f t h e u l t r a s o n i c l e v e l probe ins t a l l e d i n t h e M*SRF: f u e l s t o r a g e t a n k were continued without success. Te s t i n g of a NaK- f i l l e d d i f f e r e n t i a l p r e s sure tra.nsmri.tt er which f a i l e d i n s e r v i c e a t t h e MSW w a s continued. Performanee of the i n s t r u ment was improved by r e f i l l i n g w i t h s i l i c o n e o i l b u t 5.s s t i l l n o t sati.sfactory

Performance of t h e b a l l - f l o a b - t y p e transmi”iter i n s t a U e d a t t h e Some d i f f i c u l t i e s were experienced with a s i m i l a r ( p r o t o t y p e ) t r a n s m i t t e r on .the MSRE pump t e s t loop; however, t h e s e t r o u b l e s were a n t i c i p a t e d and c o r s e c t c d i n t h e design of t h e K9IiE model.

MSRE continues t o be s a t i s f a c t o - r y .

Performance of t h e conductiv-ity-type l e v e l probes i n s t a l l e d i n the

MSRE d r a i n t a n k s continues t o be a c c e p t a b l e .

Observation of iiie performance of 110 s i n g l e - p o i n t temperaturealarm switches i s continuing. Data obtaimed t o date a r e i n s u f f i c i e n t -to determine whether s e t - p o i n t d r i f t i n t h e s e switches i.s excessive. T e s t i n g o f a l t e r n a t e t r i m m a t e r i a l combinations f o r t h e helium cont r o l valves was terminated. Some a d d i t i o n a l valve f a i l u r e s have occurred. R e s u l t s of f i n a l checks i n d i c a t e t h a t e r r o r s i n t h e c o o l a n t - s a l t r a d i a t o r d i f f e r e n t i a l temperature s i g n a l , produced by thermocouple and lead- w i r e m i snixtc h, have been e lirninat e d D r i f t t e s t i n g of s e l e c t e d MSRE-type thermocouples w a s concluded. The f i n a l teinperatixe e q u i v a l e n t d r i f t v a l u e s were between 4 k . 7 and

+6.4’F.

Performance of t h e MSRE temperature scanning system continues t o be s a t i s f a c t o r y . C a l i b r a t i o n d r i f t appears to have been el.iminated, and r e l i a b i l i t y i s much b e t t e r than. had been expected.

xi 3.

& K B E Reactor Analysis

For t h e purpose of on-line coniputation o f c o n t r o l rod r e a c t i v i t y with t h e TRW-340 data logger, a mathematical forrriula was rCi-t;'l;ed- t o the rod-worth vs p o s i t i o n c u r v e s o b t a i n e d from c a l i b r a t i o n experimnts Tlne forin of t h e e x p r e s s i o n used was obtained by applying a p e r t u r b a t i o n technique t o e v a l u a t e t h e i n t e g r s l e x p r e s s i o n f o r the rod r'eac-Livity. A l i n e a r l e a s t - s q u a r e s c u r v e - f i t t i n g procedure was then used. to e v a l u a t e -!;he unknown c o e f f i c i e n t s i l ? _ t h e r e s u l t i n g fLmctioria_l expression. Close agreement between c a l c u l a t e d and experimental. ciirves w a s obtained. f o r t h o s e c o n f i g u r a t i o n s of shim and r e g u l a t i n g rod;; of" i n t e r e s t i n monitori n g t h e control r o d r e a c t i v i t y during operat2on.

Theoretical. ca.1culation.s were made t o estirriat;e t h e i n f l u e n c e of the o v e r a l l s p a t i a l d i s t r i b u t i o n of 13'Xe absorbed i n pores near the g r a p ' d t e s u r f a c e s i n t h e r e a c t o r core. The purpose w a s t o determiae s-gatiai corr e c t i o n f a c t o r s f o r use i n t h e on-line c a l c u l a t i o n of '35~e r e a c t i v i t y Based on an approxirflate model. of t h e rea.ci;or core, w i t h the l%W-3.110. t h e s e cnLeulations i n d i c a t e d that the e q u i l i b r i u m 35Xe r e a c t i v i t y a t 7.0 i s reduced by a f a c t o r of about 0.7'6 r e l . a t i v e t o t h e value ab-tained from a "point" c a l c u l a t i o n . ~n a d d i t i o n , t h i s c o r r e c t i o n w a s ?oimd t o clzpend on t h e time h i s t o r y of t h e pover l e v e l . Results of c a l c u l a t i o n s are preeented for s t e p changes i n power l e v e l , i n c r e a s i n g t o a i d dec r e a s i n g from 10 Mw.

Part 2.

Materials S t u d i e s

'Thermal con.rection loops made of H s s t e l l o y N and -type 304 s t a i n l e s s s t e e l have c i r c u l a t e d molten f u e l s a l t f o r 33,000 and 22,000 hr, res p e c t i - r s e u , without i n c i d e n t . A Cb--l% Zr loop c i r c u l a t i n g l e a d at 1400째F w i t h a 40O0F .EX' was found t o produce colwnbiim c r y s t a l s by m a s s t r a n s f e r , Spr.cirflens o f f l a s t e l l o y N a n d grade CGB g r a p h i t e showed rm d e t e c t a b k changes as a r e s u l t of 1100 hr exposure t o molten f l u o r i d e s a l t s i n t h e MSlG.3 c o r e during t h e p r e c r i t i c a l , i n i t i a l c r i t i c a l , and a s s o c i a t e d %propower experiments;. Thr. r e a c t o r c o n t r o l specirnen r i g , which w i l l e s t a b l - i s h b a s e - l i n e d a t a by exposing g r a p h i t e and Hastelloy N s u r v e i l l a n c e specimens to approximately- t h e o p e r a t i n g c o n d i t i o n s of t h e MSRF: except f o r raciiaiion, has been loaded wibh salt a i d i s being c a l i b r a t e d w i t h the cornpiter tha-t monitors t h e IGRE.

Metallographic examination of capsules from i n - p i l e e x p e r b e n t MTRNo apparelit

47-6 showed no evidence of n i t r i d i n g of t h e i-lastello-y N.

change i n w a l l thickiiess o r evidence of a t t a c k was observed, although an unexplained change i n t h e e t c h i n g c h a r a c t e r i s t i c s of the g r a i n bounitari-es a t the s u r f a c e was noted. Development o f methods of j o i n i n g g r a p h i t e t o metal has incI-uded: (1)t h e design of a . t r a n s i t i o n j o i n t t o reduce shear s t r e s s e s a r i s i n g from thermal expansion d i f f e r e n c e s and ( 2 ) screening t e s t s on p o t e n t i a l brazing alloys. A s m a l l . pipe of grade CGB g r a p h i t e brazed t o molybdenum s a t i s f a c t o r i l y contained molten f l u o r i d e s a l t s a t 700째C under p r e s s u r e s of 50, 100, and 150 p s i g f o r periods of 100, 1-00, and 500 h r r e s p e c t i v e l y . T l i s i s t h e f i r s t of a s e r i e s of t e s t s of graphite-to-metal j o i n t s t o determine i f such j o i n t s a r e c o r r o s i o n r e s i s t a n t and mechanicaXy adequate for t h e requirements of molten-salt breeder r e a c t o r s . A few samples of needle-coke g r a p h i t e and i s o t r o p i c g r a p h i t e have been obtained and a r e being evalua.ted t o determine t h e i r s u i t a b i l i t y f o r use i n molten-salt breeder r e a c t o r s .

'The r a d i a t i o n - damage problems were evaluated. f o r g r a p h i t e i n advanced molten-sal'i r e a c t o r s , considering growth r a t e , c r e e p c o e f f i c i e n t , f l u x gradient, and geometric r e s t r a i n t as important f a c t o r s . 'The s t r e s s developed by d i f f e r e n t i a l grorrbh i n an i s o t r o p i c g r a p h i t e should not be allowed t o exceed t h e f r a c t u r e s t r e n g t h of t h e g r a p h i t e and t h u s cause f a i l u r e s . The estimated l i f e of g r a p h i t e i s a t l e a s t f i v e y e a r s b e f o r e f a i l u r e from i n a b i l i t y t o absorb c r e e p deformation. The major i m c e r t a i n t y nv% withseems t o be t h e ahri.lity of g r a p h i t e t o s u s t a h doses o f 2 X out loss of i n t e g r i t y . Creep-rupture l i f e of Hastelloy N w a s found t o be l e s s a f f e c t e d by irr a d i a t i o n as t h e s t r e s s l e v e l s a r e lowered. The e f f e c t s o f i r r a d i a t i o n temperaixre on t h e p o s t i r r a d i a t i o n c r e e p l i f e of air-melted hea,ts are unc e r t a i n . Vacuum-melted h e a t s show a l a r g e dependency on i r r a d i a t i o n temp e r a t u r e . Fretesi; h e a t treatmenk can improve t h e d u c t i l i t y of i r r a d i a t e d specimens. Tne creep-rupture p r o p e r t i e s of s t r u c t u r a l . material. i n the MSRE appear t o be b e t t e r than. o r i g i n a l l y p r e d i c t e d on t h e b a s i s of l i n e a r extra.poI.ation of d a t a for stress vs log of iwpture time. Experimental welds have been made t o study methods of improving the w e l d a b i l i t y of Hastelloy N.

Chemistry

Three innovations have been introduced i n t h e chemical a n a l y s i s of N3RE s a l t s : a new end. p o i n t f o r uranium t i t r a t i o n s , a new method f o r determining s t r u c t u r a l - m e t a l ions, a i d . a new method for oxide analyses. Together tiiey have given increased assurance t h a t f u e l conforms t o t h e inventory composition m d t h a t t h e chemical piirity of t h e s a l t has been maiiitained.

xiii.

Ex:mina.tion of d e y m s i t s b e l i e v e d t o have been r e s p o n s i b l e f o r t h e plugging of off-gas l i n e s i n t h e MSXE r e v e a l e d the presence of o i l and pol;rmer products presumed t o have formed from o i l . A. negligible anlowt of salt vas found. The formula f o r t h e uranium-bearing c r , s l ; a l s i n the f r o z e n Tuel has been found t o be Iii.F-UF4 r a t h e r -than 7LiF-GUF4as formerly supposed. I n a stxrjjT of tine p’hysica,l chemistry of f l u o r i d e rrlelts, vapor-pressiii-e meas-Lrerrrrents have been made f o r t h r e e compositions i n t h e LLE’-BeF’;! sy.stem.. Because of v-apor-phase a s s o c i a t i o n , t h e apparent voI.atiI.ity of IAF i n c r e a s e s w i t h decreasing c o n c e n t r a t i o n 02 1,I.F i n t h e melt MetLi0d.s have been developed f o r p r e d i c t i n g d e n s i t y , s p e c i f i c heat, and thermal c o a d u c t i v i t y i n molten f l u o r i d e s e The s o l u b i l i t y of oxide in. MF3RE-related f l u o r i d e mel.ts has been r e evaluated w i . t h improved experiments. When i n c r e a s i n g xnovxits of ZrF4, as presenl; i n t h e bERE f u e l , a r e added t o f l u s h salts, the cu.paci.ty for oxide f i r s t decreases, then i n c r e a s e s .

I n t e r e s t i n r e p r o c e s s i n g methods f o r PE13R f l u o r i d e s has led to cont i n u i n g s t u d i e s of d i s t i l l a t i o n and of chemical. r e d u c t i o n as a means of s e p a r a t i n g r a r e e a r t h s from f u e l s o r p r o t a c t i n i u m from blad<e”i;s The composition t‘nat y i e l d s b!BIYi3 ‘barren s o l v e n t as d % s t i l l a - L ehas been found; t h i s prod.uci; d i s t i l l s , l.eaving t h e r a r e e a r t h s behind. A-lloys of bisniuth conS,aini.ng a smll amount of I.ithiwn have proved very e f f e c t i v e f o r r e d ~ i c i n gand e x t r a c t i n g rare e z r t h s i n t o a l i q u i d - m e t a l phase. Thoriwn has been found e f f e c t i v e as a reducing agent f o r removing pro-tactinium from Frotactinimi can a l s o be removed on Zr02. b3.anket m e l t s . The i n - p i l e m o l t e n - s a l t loop experiment and a s s o c i a t e d m x i l i a r y equipment a r e being f a b r i c a t e d and assembled so t h a t modifications to bcaurl hole €UiI-l i n t h e ORR m d i n s t a l l a t i o n of equipment can begin i n

Apri 1*

The p r e c i s i o n and accuracy of t h e h y d r o f l u o r i n a t i o n rxethod for determining oxide i n ,%RE: s a l t s ‘were e s t a b l i s h e d . Th.e method w a s a p p l i e d to t h e a n a l p i s of nonradioactive samples t a k e n during th.e s t a r t u p of t h e MSR; t h e r e s u l t s were i n reasonable agreement w i t h t h o s e obtained by t h e KBrF’4 method-. Tne -hydro2l u o r i n a t i o n apparatus f o r the determination of oxide i n r a d i o a c t i v e samples w a s f a l i r i c a t e d and -tested and. i s now being i n s t a l l e d i n a hot ceJ.1.

Zoriic iron and n i c k e l were determined v o l t m m e t r i c a l l y on a sample of molter?_f u e l withdrawn from t h e MSR. These measwrerrtents i n d i c a t e that t h e r m j o r f r a c t i o n of i r o n and of nickel i n t h e f u e l i s p r e s e n t i.n an wi-iocized state, presumably a s f i n e l y d i v i d e d metal. .Also, a welldefined v o l t m i e t r i c wave f o r t h e r e d u c t i o n U(ITS) --+ U(II1) was observed.

xi.v

Effor Ls were conti-nued on t h e development and ? v a l u a t i o n o f eqixipment and procedures f o r analyziiig r a d i o a c t i v e MSRE s a l t samples. 'The coulometric uranium procedure w a s mnodiTied Lo e1irnina;te a negative b i a s .

Boi;h f l u s h - and f u e l - s a l t samples were analyzed f o r U, Z r , C r , Be, F, Fe, Ni, and Mo. The analyses were r o u t i n e l y performed. i n t h e hot c e l l s of t h e High-Radiation-Level AiiaIytT c a l Laboratory. The q u a l i t y control. program w a s continued during t h e p a s t period. The r e s u l t s obtained on syn-Lhetic sol1ntri.on.s e s t a b l i s h e d more r e a l i s t i c l i r n i t s of e:~"rorf o r t h e methods employed.

6. Molten-Salt Breed-er Reactor Design Studies Design and e v a l u a t i o n s t u d i e s were made of thermal molten-salt breeder r e a c t o r s (MSBR) i n o r d e r t o a s s e s s t h e i r economic a n d . nilclear p o t e n t i a l and t o i d e n t i f y important design avld develo,pnent problems. The MSBR r e f e r e n c e design concept i s a two-region, two-fluid system with f u e l s a l t s e p a r a t e d f r o m t h e b l a n k e t s a l t by g r a p h i t e tubes. The energy produced. i n t h e r e a c t o r Yluid i s t r a n s f e r r e d t o a secondary cool-ant-salt c i r c u i t which couples t h e r e a c t o r t o a s u p e r c r i t i c a l steam c y c l e . Ons i t e f l u o r i d e v o l a t i l i t y processing ris employed, which l e a d s t o low u n i t processing c o s t s and economic r e a c t o r opera-tloa as a thermal breeder. T'he r e s u l t i n g power c o s t i s e s t i m a t e d t o be 2.7 m i l l s / k w h r f o r h v e s t o r owned u t i l i t i e s ; t h e a s s o c i a t e d f u e l cycle c o s t i s 0.45 m i l l / h h r ( e l e c t r i c a l ) ; the s p e c t f i c f i s s i l e inventory i s 0.8 kg/Mw ( e l e c t r i c a l ) ; and t h e fuel. doubling time i s 21 y e a r s . Development of a protactinium removal scheme f o r the b l a n k e t r e g i o n of the MSBR coixld l e a d t o power c o s t s of 2.6 rnriU.s/kwhr ( e l e c t r i c a l ) , a fuel. c y c l e c o s t of 0.33 m i . l . l / k w h r ( e l e c t r i c a l ) , a s p e c i f i c f i s s i l e inventory of 0.7 ~ ~ / M S (Te l e c t r i c a l ) , and a f u e l doubling t i m e of l3 y e a r s .

Molten-Salt Heactor Processing S t u d i e s

A close-coupled f a c i . l i t y f o r processiiig t h e fuel- and f e r t i l e streams wt1.l be an i n t e g r a l p a r t of a molten-salt b r e e d e r r e a c t o r system. The f u e l s a l t w i l l . be processed on a 40-day c y c l e . The uranium w i l l h e r e moved from t h e c a r r i e r s a l t and f i s s i o n products by f l u o r i n a t i o n , and t h e c a r r i e r s a l t w i l l be recovered from t h e fri.ssion prodix.l;s by a semicont-inuous vaciiixm d . i s t i l l a t i o n . R e l a t i v e v o l a t i l i t i e s between l i t h i u m and t h e r a r e e a r t h s have been measured t o be 0 . 0 1 t o 0.04 a t 900 t o 1050'C. Tfle recons,Litution of the r u e 1 s a l t , by combining t h e p i x i f l e d c a r r i e r s a l t with t h e p u r i f i e d uF6, can be d.one by d i r e c t absorption o f t h e UF6 i n f u e l s a l t which a h e a w c o n t a i n s some UF4 and. subsequent r e d u c t i o n of Experimental t h e i n t e r m e d i a k uranium f l u o r i d e t o UF4 with hydrogen tests showed r a p i d and compkLe ahsorptton. The primary pro'ulems j.n conLinuous f l u o r i n a t i o n of t h e f u e l s a l t to remove t h e uranium a r e corrosion I

and g e t t i n g adequate mass t r a n s f e r and countercurrent flow t o a s s u r e good recovery. Corrosion c a n probably be eliminated by the use of a l a y e r of frozen s a l t on t h e w a l l of t h e v e s s e l . Experimental work with a s m a l l countercurrent continuous f l u o r i n a t o r gave r e c o v e r i e s of 90 t o 96$ of t'ne uxranium. F l u o r i n a t i o n daring the processing of t h e fuel from the I%FB produces v o l a t i l e chromium f l u o r i d e s . These can be e f f e c t i v e l y trapped, with n e g l i g i b l e uranium losses, by use of sodium f l u o r i d e beds. A preliminary design study has been made on a conceptual processing p2.aa.t i n corporating t h e above concepts. Among the p r o b l e m which t h i s study i l h m i n a t e d were t h e complications from t h e handling of high-heatgenerating m a t e r i a l s . The f i x e d c a p i t a l c o s t Tor t h e conceptual plmt w a s $ 5 . 3 million; t h e s a l t inventory c o s t was $0.196 million, and t h e d i r e c t operating c o s t was $747,790.00 per year.

INTRODUCTIOBT

%he Molten-Salt Reactor Program i s concerned wi-th research and development f o r nuclear r e a c t o r s t h a t use mobile f'uels, which are solut i o n s of f i s s i l e and f e r t i l e materials i n s u i t a b l e c a r r i e r s a l t s . 'The program i s an outgrowth of t h e MP e f f o r t s t o make a molten-salt r e a c t o r power pl-ant f o r a i r c r a f t and i s extending t h e technology originattea t h e r e t o .the development of r e a c t o r s f o r producing low-cost power f o r c i v i l i a n uses"

The major g o a l of t h e program i s to develop a - t h e ~ m a .breeder l reactor. Riel f o r t h i s type 01' r e a c t o r would- be 233UP4 OT 2 3 5 U F ~d i s s o l v e d i n a salt of cornposition n e a r 2LiF-BF2. The blanket would be ThF4 d i s solved in a c a r r i e r of s i m i l a r composition. The technology being d - e v e l -

oped. f o r t h e breeder i s a p p l i c a b l e t o , and c o u l d be e x p l o i t e d sooner i n , aci-vL;ricedconverter reactors o r i n burners of f i s s i o n a b l e uranium and p1.utoniwn -that alh o use f l u o r i d e fiiels, S o l u t i o n s of uranium, plutoniurrl, and thorium s a l t s i n c h l o r i d e and f l u o r i d e c a r r i e r s a l t s o f f e r a t t r a c t i v e p o s s i b i l i t i e s f o r mobile f'uels f o r i n t e m e d t a t e and f a s t breeder r e a c t o r s . T'he f a s t r e a c t o r s are of i n t e r e s t t o o but a r e not a s i g n i f i c a n t par-l; of the ~ ~ O ~ Y : E U I I .

Our major e f f o r t i s being a p p l i e d t o t h e developmiit, c o n s t r u c t i o n , mid o p e r a t i o n o f iz Molten-Sa1.t Reactor Experiment. The purpose of this E q e r i m e n t i s t o txst t h e types of ~Tuelsarid m a t e r i a l s t h a t -would be used i n t h e thermal breeder and t h e converter r e a c t o r s and t o o b t a l n s e v e r a l years of' experience with the o p e r a t i o n and maintenance of a m a l l moltens a l t power reac.tor. A succes:~t'lxlexperiment wfll demonstrate on a small scale t h e a t t r a c t i v e f e a t u r e s and t h e t e c h ~ i i c a lf e a s i b i l i t y of these qysterns for. l a r g e eivj-liari power r e a c t o r s . 'The MSm o p e r a t e s at, 1200째F and a;i; atmospheric p r e s s u r e and w i l l generate 10 llw of h e a t . I n L t i a l l y , the fuel co-o.tai.ns 0.3 mole $ UF4, 5 niole $ Z r F 4 29.1 mole 76 ReF2, aild 65 me melting p o i n t i s rnole $ LiF, a:nd t h e urant-mn i s about 3% 2 3 % . B40"F. In l a t e r . operation, we expect t o use highly enriched uranjum i n t h e l o w e r eoncen%ration ty-prical o f the f u ~ fl o r t h e core of a breeder. I n each case, the composition (sf -the solvent c a n be ad.just,ed t o ret,ain a.bout the sane l i y u f d u s temperature.

The el c i r c u l a t e s through a r e a c t o r v e s s e l and zn externa.1 pump and hez%-exchange system. A l l % h i s equipment is constructed o f Hastelloy 11," a nev n-ickel-~noI.ybdemwn-cl-ir~mii~~ a l l o y with e x c e p t i o n a l r e s i s t a n c e t o c o r r o s i o n by mol-ten fl-uorides and wj-th high strength a t high -t;e~nperat i r e . The r e a c t o r core c o n t a i n s an zssernbly of gra.phit,e mod?rator ' b a r s t h a t are i n d i r e c t c o n t a c t with the mel. The g r a p h i t e j.s a new m a t e r i a l 2 of high Ciensity and small pore s i z e . T h e Riel. s a l t does not wet t h e gi:aphite and i;herefore should not e n t e r the pores, even xt p r e s s u r e s w e l l

above t h e operating pressure.

sold corrlrnercialIy ab Trico NO. WG. 2Grade CGR, pyoduced by Carbon Products Divisiori of Union Carbi.de

'-ALSO COTJ

Heat produced i n t h e 1-eactor i s t r a n s f red t o a coolant s a l t i n t h e h e a t exchanger, and t h e coolant s a l t i s pumped t'nrou-gh a r a d i a t o r t o d - i s s i p a t e the h e a t t o t h e atmosphei-e. A small f a c i l i t y i.s ins-Lalled i n the MSRF: b u i l d i n g f o r occasionally processing t h e f u e l by treatment with gaseous H F and F2. Design of t h e MSF3 w a s begun e a r l y i n t h e s i . m e r o f 1960.

Orders

fov s p e c i a l m a t e r i a l s were placed i n t h e spring of 1961. Major modifiea-Lions -to l h i l d i n g 7503 a t OFXI,, i n which -the r e a c t o r i s instal-led., were s t a r t e d i l l t h e fa1.l of 1961 and were completed by January 1963.

F a b r i c a t i o n of t h e r e a c t o r equipment w a s begun e a r l y i n 1.952. Some d i f f i c u l t i e s were experienced i n obtaining m a t e r i a l s and i n making a-nd i n s t a l l - i n g t h e equipment, b u t t h e e s s e n - t i a l t n s t a l l a t i o n s were completed so t h a t preiiucleaj: tes-ti1i.g could begin i n August o~t' 1.964. The p r e n u c k a r t e s t i n g w a s complkted with only minor d i f f i c u l t i e s i n March of 1965. Some modifications were mad.e before bzginninz t h e c r i t i c a l experiments i n May, and- t h e r e a c t o r w a s fii-st c r i t i c a l on June l., 1965. The zeropower experiments were completed ear1.y i.n J u l y . AddPi-Lional. modificat i o n s , maintenance, and sea.l.i.ng and testing of t h e containment were required- before t h e r e a c t o r beean t o operate a t apnreejable power. This work w a s completed i n December, and t h e power experiments were begun i n January 1966. Tke r e a c t o r had. been operated f o r a short time ai; 1. Mw a t the -tLme of t1nri.s repor'c. Ehrther i n c r e a s e s i n power were delayed by d i f f i c u l t i e s with t h e off-gas system. Because t h e MSIa i s of a new and advanced type, s u b s t a n t i a l research and developrneiit e f f o r t i s proviideil. ri.n support or t h e design and constixct i o n . Includzd a r e engineering development and. tes-tirig of r e a c t o r components and systems, me t;al.l~urgical.developrnent of m a t e r i a l s , and stud.ies o f t h e chemistiy of t'ne s a l t s a,nd t'neir c o m p a t i b i l i t y with graphibe ard meta1.s both i n - p i l e and o u t - o f - p i l e . Work i s a l s o being dolie on methods f o r purif'ying t h e f u e l s a l t s avld i n preparing p u r i f i e d mixtures f o r t'ne r e a c t o r and f o r t h e research and development s t u d i e s . Some z t u d i e s a r e being made of t h e l a r g e power breeder r e a c t o r s f o r whtch t h i s technologyi s being developed.. This r e p o r t i s one of a s e r i e s of p e r i o d i c r e p o r t s i n which we des c r i b e b r i e f l y t h e progress of t h e program. ORNL-3708 i s an especial-Ly useful r e p o r t because it g i v e s a thorough yeview of t h e design and construc'cion and supporting developrneiit work f o r t h e MSE. It a l s o des c r i b e s much of t h e g e n e r a l technology- f o r mol.ten-salt r e a c t o r systems. 0-Lher r e p o r t s i s s u e d i n t h i s s e r i e s a r e :

ORNL-2474

OIWL-2626

omJ- 2 684

OKnTc,- 2723

0RIdL - 2799

om,- 2890

Period. Ending January 31, 1.958 Period Ending October 31, 1958

Period Ending January- 31., 1.959

Period End7.n.g April 30, 1959

Period Ending J u l y 31., 1959

Period Ead.:i.ng October 31, 1959

OEwIr-2973

P e r i o d s Ending Janua-ry 31 and A p r i l 30, 1960

ORNL-3014. OEWL-3122

P e r i o d Ending July 31, 1960

OIWL- 3282

Period Ending February 28, 1962

ORNL-3215

P e r i o d Ending February 28, 1961 Period Ending August; 31, 1961

ORNL-3369

Period Ending August 31, 1962

O R G -3419 OX& - 3529

Period Ending January 31, 1963

Period Ending J u l y 31, 1963

ORNL-3708

Period Ending J u l y 31, 1.964

ORTL-3626

Period Ending January 31, 1964

ORNL-3812

Period Ending February 38, 1965

OlwL- 3872

P e r i o d Ending August 31, 1965

P a r t I..

MSRE OPERATIONS AND CONSTRUCTION, ENGINEERING ANALYSIS, AND COMPOfKENT DEVELOPMENT

1. MSFiE OPEIUTIOMS

Chronoloaical Account P r e p a r a t i o n s f o r o p e r a t i o n a t high power were completed, ,and t h e exp e r i m e n t a l program w a s resumed. The power ascension was i n t e r r u p t e d a t l Nw, however, by p a r t i a l o r complete plugging a t s e v e r a l p o i n t s i n t h e f u e l off-gas system. The plugging materials were i d e n t i f i e d 8 s organics, probably t h e prod.ucts of o i l decomposition. F i g u r e 1.1 o u t l i n e s t h e major a c t i v i t i e s i n t h e p e r i o d covered by t h i s r e p o r t . A b r i e f account follows; d e t a i l s are given i n l a t e r s e c -

tions.

Two of t h e l a r g e r m o d i f i c a t i o n jobs scheduled b e f o r e power operat i o n , t h e c o o l a n t l i n e anchor s l e e v e s and t h e i n s t a l l a t i o n of new rad i a t o r doors, were completed i n A u g u s t . Late t h a t month, t h e assembly of g r a p h i t e and R a s t e l l o y N surveil1,ance specimens, which had been i n t h e c o r e froxi t h e beginning of s a l t o p e r a t i o n , w a s removed. While t h e r e a c t o r v e s s e l was open, i n s p e c t i o n r e v e a l e d that p i e c e s were broken from t h e h o r i z o n t a l g r a p h i t e bar supporting t h e smiple a r r a y . Tlne p i e c e s 'were recovered f o r examination, and a new scample assembly, designed- f o r exposure a t high -power and suspended f roin above w a s i n s t a l . l e d .

The f u e l pump r o t a r y element w a s removed i n a %ina,l r e h e a r s a l of remote maintenance and t o permit i n s p e c t i o n of t h e pwnp i n t e r r t a l s . It w a s r e i n s t a l l e d a f t e r i n s p e c t i o n showed the p m p t o be i n verjr good. condition.

T e s t s had shown t h a t h e a t s of B a s t e l l o y N used i n %he r e a c t o r vessel had- poor high-temperature r u p t u r e l i f e and d u c t i l i t y i n -the as-wel&cl c o n d i t i o n . The v e s s e l c l o s u r e weld had not been h e a t t r e a t e d , so it vas h e a t e d t o I4,OO0F f o r 100 h r , using t h e i n s t a l l e d h e a t e r s , t o iuiyrove t h e s e properties. At t h e conclusion of t h e h e a t t r e a t m e n t , t h e r e a c t o r c e l l . was sealed f o r t h e f i r s t t i m e . The d r a i n c e l l . had a l r e a d y been seal.ed, and some of

F i g . 1.1. MSEE Operations and Maintenance, September 1965-Febr~ary

1966.

8 Now t e s k ing of t h e conta,inment provided by %he r e a c t o r c e l l , d r a i n c e l l , and vaporcondensing system became t h e primary e f f o r t . A f t e r p r e l i m i n a r y t e s t s a t p r e s s i x e s up t o 5 p s i g , t h e program was i n t e r r u p t e d on October 21 t o i n s t a l l blasonite s h e e t s between -the c e l l meinbranes and upper blocks t o mod?.fy t h e access opening over t h e c o r e . T e s t i n g a”i, 20 p s i g disclosed many s m a l l l e a k s a t p e n e t r a t i o n s , which were r e p a i r e d (many while t h e r e a c t o r c e l l was open f o r t e n days f o r stra5.n-gage measurements of p i p ing s t r e s s e s 1. A f t e r t h e repai-rs, leakage r a t e s were memured a t LO, 20, and 30 p s i g . E x t r a p o l a t i o n -to 39 p s i g ( t h e peak p r e s s u r e in t h e rflaximurn c r e d i b l e a c c i d e n t ) gave a l e a k rate of 0.4$/day, compared t o l.O$/day assumed i n t h e s a f e t y a n a l y s i s . Leakage r a t e s a t -2 psTg ( t h e normal o p e r a t i n g p r e s s u r e ) were measured t o s e r v e as a r e f e r e n c e d-uriag subsequent o p e r a t i o n . T h i s progmm w a s completed on Deceiiiber 5 . t h e c l . o s x e devices on cnntai-men%p e n e t r a t i o n s had been t e s t e d .

S t r e s s e s i n t h e r e a c t o r cell p i p i n g aiid v e s s e l s were c a l c u l a t e d i n d e t a i l t o permit e v a l u a t i o n of t h e s e r v i c e l i f e of t h e Rastel..Loy N p a r t s under i r r a d i a t i o n . Some adjustments of supports were made t o nllinimtze s t r e s s e s , a f t e r which -the ca,lcK.ated s t r e s s e s were acceptably l o w exc e p t a t .the h e a t exchanger nozzles, where a complicated geometry- inade cal.eulati.ons u n r e l i a b l e . The s t r a i n - g a g e measurerneiits 5.n e a r l y Novemb e r showed t o l e r a b l e s t r e s s e s a t t h i s p o i n t aJ-so. While t h e contaimnent t e s t i n g ; and s t r a i n - g a g e measurements were under way, t h e o p e r a t o r s and s u p e r v i s o r s underwent h r % h e r t r a i n i n g w i t h emphasis on power o p e r a t i o n . Classroom l e c t w e s were followed by p r a c t i c e on a simula’hr which included t h e a c t u a l c o n t r o l s instrumen-. ExaminaLions and c e r t i f i c a t a t i o n , control rods, and r a d i a t o r d.oors t i o n of q u a l i f i e d o p e r a t o r s followed.

.’

E a r l y t e s t s w i t h the r a d i a t o r hot and the e x e r c i s e s during s i m u l a t o r p r a c t i c e showed t h a t t h e o p e r a t i o n of t h e r a d i a t o r doors was iitire1iabl.e.

Four weeks i n Novertiber and December were spent i a modTfying

and a d j u s t i n g t h e door r o l l e r s , t r a c k s , seals, and l i m i t devices b e f o r e

t e s t s showed t h e y would. operate r e l i a b l y hot

cold.

A i r leakage f r o m t h e r a d i a t o r e n c l o s u e when t h e main blowers were operated proved t o ’ne excessive, b o t h from t h e s t a n d p o i n t o f coolantcell. ventj.3.ation c a p a c i t y and because of excessive h e a t i n g o u t s i d e of t h c e n c l o s u r e . Roods were instal..led., i n t o which t h e r a d i a t o r doors r e t r a c t e d , and t h e sheet-metal enclosure w a s general-1.y t i g h t e n e d and m0d.ff i e d b e f o r e leakage became a c c e p t a b l e . (Even a f t e r ,the i:rrprovemeiits it was necessary t o supplement t h e cel.2- exhaust w i t h ducting i;o one alrmul.izs blower to a t t a i n a negative p r e s s u r e i n t h e c o o l a n t c e l l . )

When t h e rmin r a d i a t o r blowers were operated w i t h t h e r a d i a t o r h o t , a i r l e a k i n g from t h e t o p of t h e enclosure overheated e l e c t r i c a l i n s u l a t i o n i n t h a t a r e a . It was necessary t o i n s t a l l ceramic i h s u l a t i o n on l e a d s on t o p of the r a d i a t o r and r e r o u t e t h e l e a d s t o c o o l e r l o c a - t i o n s . Ducting was a l s o i n s t a l l e d t o :redirect cooling a i r flow a c r o s s t h e t o p of t h e enclosure where t h e door hoods had blocked t h e original. flow p a t term e

The r a d i a t o r work l a s t e d from e a r l y November t o mid-January, delayi n g t h e f i l l i n g of t h e c o o l a n t system and t h e s t a r t of power o p e r a t i o n .

As soon as containment t e s t i n g was f i n i s h e d , t h e instrwrierits, cont r a l s , a i d equipment 'were given the checkouts reqy.irei1. p r i o r t o s t a r b u p . The f i n e l system was t h e n heated, and I"lus11 s a l t w a s c i r c u l a t e d f o r t h r e e Samples of t h e f l u s h s a l t t a k e n at .this time were anaLjzed- for days. oxides by an inproved, a o r e r e l i a b l e method. R e s u l t s averaged I.ess than 1.cIc) ppm, w e l l below t o l e r a b l e levels. (Evidently -tile meas'ures taken t o avoid oxygen contzmination while t h e r e a c t o r vessel and f u e l pix~pwere open were e f f e c t i v e . 1 Fuel- s a l t was charged i n t o t h e loop, and t h e r e a c t o r wzs talien c r i t i c a l on Deceniber- 20. Between t h e n arid January 18, when t h e c o o l a n t loop was f i l l e d , n u c l e a r experiiiients were r e s t r i c t e d t o powers below 25 I w Even SO, useful measurements were made on f l u d i s t r i b i n t i o n s i n -the t h e m 1 s h i e l d and b e s i d e t h e r e a c t o r vessel, c o n t r o l rod sha.d.cn.rl.ng e f f e c t s , and zero-power k i n e t i c s of %he n u c l e a r system. A t tihe sane time, numerous fuel-salt samples were analyzed, showing ura.nl.im i n excellent; agreement with e x p e c t a t i o n s , low oxide conceritration, arid p r a c t i c a l l y no c o r r o s i o n .

With t h e c o o l a n t systemri i n Gperation, the p w e r was r a i s e d t o LOO, 500, and then 1000 kw as h e a t w a s exbracted a,t t h e radjator. Cjrniwnics t e s t s and h e a t balances were eond-ucted a t each puwer. Cn Janimry 23, while t h e power was 'at 500 kw, -the f i ~ e pressure l c o n t r o l valve ( o r its f i l t e r ) showed s i g n s of plugging, b u t t'he s i t w i t i o n el.ea,red up 5x1 a few hoilrs. There was a l s o evidence of a n abnol-rnal r e s t r i c t i o n i n tine equalizing line between the Tuel p w r ~and t h e d r a i n t a n k s . The _riext day %he reactor w a s t a k e n t o I &, a,nd a few horns l a t e r s i g n s of i x t e r m i t t e n t plugging i n t h e f u e l off-gas l i n e a g a i n appeared. It we.s esta'olished t h e n t h a t t h e e q u a l i z i n g l i n e was completely plugged. When it was a l s o discovered t h a t the auxiliary v e n t l i n e was almost compl.et,ely plugged, t h e reactor w a s t a k e n s u b c r i t i c a l . E f f o r t s t o blow out t'rie plugs i n t h e e q u a l i z i n g l i n e arid t h e a u x i l i a r y v e n t l i n e f a i l e d , and the f u e l %id ccolant loops were drained- t o s1iut down t h e r e a c t o r . ('The systems were kept h o t I w i t h heliwrn ci.rcuLating. 1 The check valve i n t h e v e n t . l i n e t o t h e aux5,liary charccJal bed w a s removed, and t h e l i n e was recormected. Gas t h e n f r e e l y passed through t h e liner.;. The f u e l ctrain cell was opened, arid t h e f l o w - r e s t r i c t i n g c a p i l l a r y i n the equalizing l i n e was removed. 'This l i r i e t h e n proved t o be clear. 'The check valve and capiLla,ry were t a k e n t o Y k Hiigh-RadiationLevel &amination Laboratory (HRLEL), where t h e y were observed t o ContaiIi s n l a l l aounts of i n t e n s e l y r a d i o a c t i v e m a t e r i a l . Tiley were not plugged., however. Meanwhile Yhe plugging of t h e f u e l pressure con-Lrol valve (or f i l t e r ) r e c u r r e d . Blowing backward through t h e l i n e did n o t c l e a r t h e o b s t r u c t i o n , s o t h e assembly of valve and f i l t e %was rernoved. A new valve was (This i n s t a l l e d , and t h e assembly was r e p l a c e d t o see i f i-t w e r e open. w a s siinpler t h a n flow t e s t i n g t h e contaminated p a r t s o u t s i d e 'Lhe system.) A t f i r s t t h e pressure drop w a s a c c e p t a b l e , 'auk over a. f e w hoixs, excessive p r e s s u r e drop again developed. A f t e r t h e assembly w a s removed, the new valve was proved t o be c l e a r , s o t h e f i l t e r was t a k e n t o -the HEXEL for examination. The o l d pressure c o n t r o l valve was also czit open and exarnined i n t h e IBIXL after flow t e s t s showed i t s C, w a s a f a c t o r of

3 hel.ow i.Ls orlgiiia?. v a l u e . There was some s o l i d m L e r i a i i n the pores of the f i l . t e r , b u t the pressure drop across t h e f t l . . t e r w a s not as high as it had apparentlay been while instal.l.ed. 1nspec.Lion showed. that t h e valve t r i m w a s coa'ced w?.tli o i l and v a r n i s h - l i k e m a t e r i a l . The t o t a l amount of maberial i n t h e valves and f i l t e r w a s q u i t e Therefore we decided t o resu11ie o p e r a t i o n s , w i n g a T i l t e r w i t h l a r g e r pores (50 p i n s t e a d of 1 p ) and c o n t r o l l i n g pressux-e w i t h a hand valve (Cv = 1 . 0 ) a l r e a d y i n the l i n e i n s t e a d of t h e pressirre control. valve (c, = 0.07). (The p r e s s u r e control. val.ve was e l i m i n a t e d . ) SIixi..?.

During t h e o p e r a t i o n a-i; s i g n i f i c a n t power, a c t i v a t i o n of potassium in the cooling water corrosion i n h i b i t o r h a d been more -than expected..

While tlie r e a c t o r w a s s h u t dkiwn, t h e o r i g i n a l c o r r o s i o n i.nbibi'l;or. was r e p l a c e d wi.t;h 'Li i z i t r i t c and b o r a t e , which would g i v e only a small. amount of a c t i v i - t y (tritium)

Also whil-e t h e reacLor was down, p r e s s u r e drops across t h e c h a r c o a l beds were measured. There had been -int,emLttent i n d i c a t i o n s oP excessive p r e s s u r e d.rops during t h e l - P h o p e r a t i o n and just a:ftema.rdl b u t ;,:h.er?. measured b e f o r e t'ne iiext s.bari;up t h e y were normal. Operators a n d ex-tension handles on t h e charcoal-bed liaiid. v a l v e s had been r e p a i r e d dui"Lq< this interval. ( I c e , rust, and binding had prevented. easy o p e r a t i o n , and- setscreTws i n t w o of t h e ex-Lensions liad s h e a r e d . ) Operati-on w a s resumed, and.. f u e l was c i r c u l a t e d for 4.4 hi- b e f o r e - t h e power was r a i s e d t o 1. Mw. It w a s necessary to gradual-ly open t h e hand val-c-e being used f o r pressure c o n t r o l about 1/4 turn dinring t h i s period, i n order t o hold. t h e fuel p r e s s i x e lin t h e range of 4 t o 6 psig. The i m p l i c a t i o n w a s t h a t 8, s m a l l am.ouit (perhaps 0.01 i n . of matcr?'.al.. had built up on t h e valve trim. Within 3 hr a f t e r goi.ng t o 1. Mw, .LIE ap-. p a r e n t accimuJ-ation of material. a c c e l e r a t e d . 'The valve w a s adjilsted t o I m i n t a i n c o n t r o l , b u t a s h o r t time a f t e r maki.ng an unusually l a r s e adjus'cmcnt, t h e differen'ilial p r e s s w e a c r o s s Lhe charcoal..bed and v a l v e s suddenly increased., i i i d i c a t i n s blockage i n t h o s e l i n e s .

Just a t t h i s p o i n t , t h e motor on Lhe space c o o l e r i n t h e fuel d r a i n c e l l f a i l e d . Rising temperatures in t h i s c e l l t h e n r e q u i r e d t h a t t h e f u e l . be d r a i n e d and. secured s o t h e c e l l couJ.d. b e opened.

The remainder of t h e p e r i o d w a s spent i n repla.cj.ng the space c o o l e r motor and i n v e s t t g a t i n g t h e trou'ole i n t h e off-gas system.

Analvsi s of F m ier 3-ments Reac-ti v i t y Balance

The r e a c t i v i t y - balance 3.nvolves c a l c u l a t i o i i o f t h e e f f e c t s oi" charges i n a l l known v a r i a b l e s a f f e c t i - n g r e a c t i v i t y . The i.1e.t effect of changes between any two ti:mes t h a t t h e r e a c t o r i s c r i t i c a l should be z e r o -if tile calcixl-ations are accurat,e. Deviations Ti-om zero indiicate e i t h e r e r r o r i n . the measuremenLs a ~ i dc a l c u l a t i o n s or suile vjnforseen e f f e c t .

11 The r e f e r e n c e c o n d i t i o n s f o r t h e r e a c t i v i t y balance were e s t a b l i s h e d ( t h e zero-power experiments which ended July 4 , 1965). Between then and Lhe s t a r t u p i n December, one v a r i a b l e changed s i g n i f i c a n t l y the 235U c o n c e n t r a t i o n i n t h e fuel. Because of uranium additions t o t h e c i r c u l a t i n g f u e l , a t -the end of run 3 t h e 235U c o n c e n t r a t i o n i n t h e l o o p w a s a'oout; 10$ higher t h a n that i n the s d t rerma.ining i n - k h e d r a i n -Lads. Thus %he d r a i n and- mixing at t h e end of rim. 3 cailsed a s u b s t m t i a l decrease i n 235U c o n c e u t r a t i o n , b u t one that couLs1 be c a l c u l a t e d . On the o t h e r hand, t h e f u e l loop w a s flushed a-t t h e end of run 3 and t h e beginning of rut? 4-, r e s u l t i n g i n mixing irrto t h e f u e l an rm-aluit 03 f l u s h salt which w a s probably small but was not d i r e c t l y measurable. Before c r i t i c a l i t y i n rim 4. the 235U concesrtration was c a l c u h t e d , assuming E d i l u t i o n wiLh f l u s h s a l t . The change in c o n c e n t r a t i o n from r w ~3 w a s coriverted into r e a c t i v i t y change, using t h e colicwitration c o e f f i c i e n % of r e a c t i v i t y t h a t had been observed in t h e zero-power experiments. 2 "he r e s u j - t m t r e a c t i v i t y was eonver-ted t o a predicted. c o n t r o l - r o d conf i g u r a t i o n Tor c r i t i c a l i t y a t 120(3"F a n d zero power, using t l r e c o n t r o l rod poisoning r e p r e s e n t a t i o n based 011 t h e rod c a l i b r a t i o n s . (See 'I'4SlGl Reactor k i a L y s i s , " this r e p o r t , f o r a discussion of t h e eqm-Lion f o r r o d poisoning. ) The p r e d i c t e d c r i t i c a l p o s i t i o n of tlie r e g u l a t i n g rod (rod. 1.) w i t h . the tire shim rods withdmwn 34 i n . was 24.7 i n . , and the observed cri.i;ical position was 23.3 i n . Tliis dri.fference, equival.ent to only O.OCJ./, Gk/k, rimy 'oe due t o s e v e r a l f a c t o r s , incl?ndi.ng (1)d i f f e r e n c e s in terripera t w e measurenent, ( 2 ) inventc;ry e r r o r s at the end of rrm 3 , and ( 3 ) e r r o r s in the rod-poisoning c a l c u l a t i o n . Tine most importauit conclusion t o be draw:n from this i s t h a t t h e r e was no s i g n i f i c a n t dil.utimi of t h e f-wl salt by t h e flush-salt o p e r a t i o n . in

~ U L L3

C r t t i c a l - o p e r a t i o n of the r e a c t o r d - u i n g rims .?1. and 5 provided an o p p o r t w i i t y f o r checking out some parts of %he reactivf.ty-bal:$nee c a l cu.l_a,ti.on. The coniputer-executed r e a c t i v i t y balance w a s not used- because (I) the a c c m a t e r e p r e s e n t a t i o n of c o n t r o l - r o d poisoning had not been i n c o r p o r a t e d i n t o %"e program, (2) t h e c a l c u l a t i o n of xenon poisonirrg sms not f u l l y developed, and ( 3 ) Lhere were rindLcati.ons of o t h e r systerrBtic e r r o r s in t h e p r o g r m t h a t had riot been resolved. However, several. Inanual c a l c - d a t i o n s were made a t very low powers where t h e f i s sion product poisoning arid fuel-bu-nmp t e r m are i n s i g n i f i c a n t . Some c d c u l a t i o n s were also made a t powers up t o 1 14.w b u t witAiout t h e xenon and samarium terins.

In g e n e r a l , t h e zero-power r e a c t i v i t y balances showed a v a r i a t i o n This corresponds t o a variation of AO.3 i n . i n the of +0.02$ &/k. critical p o s i t i o n of t h e regulating r o d o r +3aF i n system t c n q e r a t u r e ami. probably r e p r e s e n t s t h e l i m i t of accuracy of t h i s p o r t i o n 02 t h e c a l c z d a t ion.

C a l c d a t i o n s a f t e r u s -to 24 hr of o p e r a t i o n a t 1 Mrs showed no meaNegl.ect of -the surable change from t h e zero-power r e a c t i v i t y 'oalarices f i s s i o n product terms should b v - e r e s u l t e d i n a change of about -0.2$ Ek/k if t h e a n t i c i p a t e d xenon behavior had occurred. T h i s i s niuch l a r g e r t h a n t h e s c a t t e r i.11t h e measurements, s o one can conclude t h a t t h e xenon poLso~itngwas a c t u a l l y much less than predic-bed.

The di-fference between ind-ica”ied arrd a c t u a l p o s i t i o n of c o n b r o l rod 3 , which developed a f t e r t h e s t a r t of run 4 (see p . 54),was r e f l e c t e d as a s h l f t of about 0.05$ 6k/k i n t h e zero-power r23.cti.vity ba,la!ice. This demonstrated t h e a b i l i t y of t h e r e a c t i v i t y bala‘nce t o show- up small cl?ai?ges, a t least uliles simple conditions, Lhat i s , no fi.ss.i.on product poisoni.ng and l . 0 ~power. Power C a l i b r a t__ ion One o b j e c t i v e of t h e e a r l y power t e s t s ?was t o c o r r e l a t e %he themal. power of t h e r e a c t o r and t h e outputs of t h e vari.ous neutron s e n s i i g e1.ements The p r i n c i p a l requirement of such a calibraLioi?. Ls an independent method f o r measuring t h e thermal or f i s s i - o n p a v e r of t h e r e a c t o r . V a r i ous methods were used i i i t h e approach t o 1 Mw w i t h reasonab1.y good agrremenL

The f i r s t approximai;ion, iised throughou.1; rm 3 , w a s bssed. oil c a l culat,:ions of t h e inhereni; (alpha-in) soixce i n t h e f u e l and subcritical.. rflultiplicatjion. The primary purpose of t h i s cal-ibi-ation w a s t o permii; posit?..oni.ng of t h e safe-t;y chambers s o t h a t t h e y would provide a c o n t r o l rod scrali a t a few k i l o w a t t s and s t i l l not i n t e r f e r e wi’ih tihe planned experiments a t lower powers. Absolute accuracy w a s not r e q u i r e d s i n c e none of t’ne experiments involved o p e r a t i o n a t powers where ‘chermial- e f f e c t s were apparent,. A the:mal-power

c a l i b r a t i o n w a s made s h o r l l y - a f - t e r - t h e start, of run

4 a-i; a nominal 25 kx. A t t h i s t:i.me, only t h e f u e l loop w a s full a n d

c i r c u l a t i n g ; t h e thermal- power w a s evaluated f r o m t h e r a t e of temperat u r e rrise and t h e knoun heat c a p a c i t y of t h e Loop. This provided a b a s i s for subsequei-tt operation at higher powers and, i n c i d e n t a l l y , showed tlnat t h e i n i t i a l source-power c a l i b r a - t i o n hac‘.been i i i e r r o r by only 8%. A s i m i l a r t e s t was performed. a t higher power wi’ih both t h e f i ~ sild l coolant loops full. and. c i r c u l a t i n g m However, t h e second t e s t w a s d i vided. i n t~ p a r t s . First, t h e nuclear power w a s set st about 75 kw, and 75 kw of e l e c t r i c a l - h e a t .input t o t h e loop was turned off. These operations d i d not l e a d t o a s’wady tejfiperature, biit t h e change i n -i;em,p e r a t i r e slope w i t h time b e f o r e and a f t e r the i n c r e a s e t o 75 kw w a s used t o c o r r e c t t h e t h e - m l . . power. The nuclear power w a s t h e n i n c r e a s e d by 50 t o 125 kw, and t h e i n c r e a s r i n -the r a t e of teniperatili-e r i s e was m e , z s u r e d . . The thermal-power cal-ribration fi-om tliese two steps w a s withri n 5% of t h e 25-kw cal-ibra-tion.

Several o v e r a l l hea-t balances were c a l c u l a t e d w i t h t h e nomri.iza,l nuc l e a r power a t l. Mw. The r e s u l t s i n run 4 v a r i e d between 0.94 and 1.-18 Mw, wikh an average value o f 1 . 0 1 MGT. In run 5 , t h e s t e a d y - s t a t e heat balances a t an indica,ted. power of 1 Mw gav-e l.19 0.02 I&. The reasons f o r t h f s apparent discrepancy have not been e s t a b l i s h e d .

F l u x measwme:tlts were nmde i n t h o n e u h u i soixce tube t o deteimine i f opel-atLon a t power ~,rouldregenerate t h e e x t e r n a l n e u t r o n soix-ce h r n -

Cm-Be) t o a s i g n i f i c a n t degree. The r e e n e r a t i o n would t a k e p l a c e as a r e s u l t OS t h e m l - n e u t r o n c a p t u r e s i n (Ti12 = 4G2 y e a r s ) , which would produce t h e more a c t i v e 242Cm (Til2 = 162.5 d a y s ) . The measurem e r i t s were made using cadmium-covered and bare copper f o i l s t o determine t h e t h e m a l - n e u t r o n f l u x a t t h e pemanent source p o s i t i o n , a n e l e v a t i o n of (330 f t 8 i n . The thermal f:Lux a t t h a t p o i n t w a s fol.md t o be 3.8 X lo7 neutrons ernm2 sec-' w i t h t h e r e a c t o r a t l . 0 2 k t r . 'This e x t r a p o l a t e s t o 3.'7 x ' 0 1 neutrons cm-2 see-' a t a power of 10 M F T . using c o n s e r v a t i v e assumptions, it w a s c a l c u l a t e d t h a t t h e source s t r e n g t h wi.11 be kept a t an a c c e p t a b l e level. f o r a t least 1-1/2 yetars a f t e r power o p e r a t i o n has

bc& 'Lln.

Flux measurements were a l s o made i n t h e r e a c t o r furnace b'4 i n . from t h e r e a c t o r v e s s e l wall.) i n t h e Location l a t e r occupied by r e t a l l u r , T' L C i t l s u r v e i l l a n c e specimens. The rrieasurements were made using gold and copper f o i l s . T'ne f o i l s were s e a l e d i n 8 s t a i n l e s s s t e e l envelope from which a i r had. been purged t o p r o t e c t t h e copper from o x i d a t i o n d ~ u i r i gt h e irrad i a t i o n at 12@0째F. Fluxes .were measured along a v e r t i c a l line 80 in. long. The peak f l u x (at approxlirnately t h e c o r e midplane ) e x t r a p o l a t e d t o a. power of 10 w a s 7 X lox2 neutrons ernw2 see-'. F a s t and thermal c o u t r i b u t i o n s t o this flux were 4.8 X I O L 2 neutrons sec" and 2.3 X neutrons cnie2 sec-' r e s p e c t i v e l y

D e scr i p t ion of Dynamic T e s t s

A riimber of djrnamic t e s t : ; were performed during operation a t zero power and subsequently a t power level;; up t o J_ Mw. Tize purpor;e of these t e s t s was t o i n v e s t i g a t e t k i e inherept s t , a l , i l i t y of t h e i;y-stem, as w e l l as t o evalua-Le t h e mathematical models and the parameters -that were used t o p r e d i c t i t s dynamic c h a r a c t e r i s t i c s . The i n h e r e n t :;t&cjFlity of t h e system (i.e., without automatic cont r o l ) was t h e subject of an exhaus-Live t h e o r e t l c a l analysis3 in i ~ h i c hit was c o n c h d e d t h a t the r e a c t o r 170uI.d be s t a b l e at a l l powers and tha-t i t s sta'ullitjr c h a r a c t e r i s t i c s would improve as t h e power l e v e l i n c r e a s e d . Tests made on the r e a c t o r o p e r a t i n g without servo c o n . t r 0 1 u t power levels of 75 kw, 465 W, and 1 Mw confirmed t h e s e p r e d L c t l o a s , a s shown i n Fig. 1.2, which shows t h e response o f t h e power t o a r b i t r a r y p e r t u r b a t i o n s . The irriprovement i n t h e n a t u r a l damping c ' c i a r a c t e r i s t i c s arid t h e decrease i n t h e p e r i o d of osciLlation- w i t h i n c r e a s i n g power I.eve1. a r e clearly sh.orm. Figure 1.3 shows a comparison O F t h e experirnen-t~3.1and i;heoreti.cal periods of oscil.l.a-t;iors.

A sul,ject of coiit;ider*able i n t e r e s t chiring t h e MSRE d.evelopmnt w a s whether o r not i;he r e a c t o r power would "waI.I.ow" when o p e r a t i n g without SCTVO control. Wallowiiig wou1.d occur i f t h e system were inustable o r if random perturbat,iona i n r e a c t i v i t j r O F c o o l i n g l o a d ind-uced Sightly damped

14 power o s c i l l a t i o n s . A t b o t h r/5 a n d 465 kw some waI.l..OwiiIg was observed, b u t t h e power l e v e l p e r t u r b a t i o n s were less t h a n +5$. I n 'uotk cases nei-ther of t h e maih r a d i a t o r blowers was on, so the bulk of t h e cooling load w a s due t o n a t u r a l convection aiiii r a d i a t i o n , a~1.d random f 1uctua-ti.ons i n load were seen. When one radi-ator m a i n blower was .turned on f o r t h e

ORNL- D W G 6 6 - 4 7 6 2

100

t 50

0 . 0 3 0.05

0.1

0.5 ! 2 N o , NUCLEAR POWET: ( M w )

0.2

1.3. Comparison of Predicted and Pkasured. 1idie.rent Periods of Oscillation at Low Powers.

15 I.-Mw case, however, t h e . b u l k of t h e c o o l i n g w a s by f o r c e d convection, arid t h e power l e v e l f l u c t u a t i o n s vere reduced considerably. Tnus, a t high.er powers n e g l i g i b l e i n h e r e n t lo~.r-freyuencyiieintron l e v e l %:Luctuations c a n be expected since t h e l o a d will be s t e a d i e r . and t h e i n h e r e n t damping of t h e system even greater.

Frequency Res-oonse Tests Both pseudorandom binary tests and pulse tests were carried. o u t i n o r d e r .Lo determine t h e frequency response of t h e system. The pseudorandom binary t e s t s c o n s i s t e d of s p e c i a l l y s e l e c t e d p e r i o d i c s e r i e s of p o s i t i v e and. negabive r e a c t i v i t y p u l s e s . ':"ne advantages of -this type of s i g n a l f o r freq1uency response t e s t i n g i n t h e NSEE a r e : 1. Te' s i g n a l may be generated w i t h standard. r e a c t o r hardware. The sequences w e r e generated u s i n g t h e MSRE t l i g i t a l coniputer and 8. p o r t a b l e analog computer -Lo c o n t r o l t h e p o s i t i o n of a r e g u l a t i n g r o d .

2. A large number of freqpencies may be analyzed 5.11 a single test, w i t h less time required to c a r r y ou-tt h e experirnents compared with t h a t r e q u i r e d f o r o s c i l l - a t o r t e s t s , vhich analyze one frequency a t a time. 3. Tne l o c a t i o n and r e l a t i v e amplitudes of the hasrmnics of t h e i n p u t s i g n a l may be a d j u s t e d by varying the 'uasic pulse o r "'bit time" and. t h e number of b i t s i n t h e secpence. The signal power i s c o n c e n t r a t e d i n specific barnonic TrequenT h i o glves a better e f f e c t i v e s i g n a l - t o - n o i s e rat5.o than -that i n rioriperiodic signals w i t h a con-tinuwn of frecpencie:; ties.

5. The ave:rage value of t h e p e r t u r b a t i o n i s e s s e n t i a l l y zero, r e s u l t i n g i n a small n e t u p s e t of the system. Pseudorandom b i n a r y t e s t s were run a t power 1.eveI.o of 100 w, 75 kw, Tine p a r t i c u l a r secpences and .their d.iration were selected s o t h a t t h e expected. low-frequency ?xsonance i n t h e frequency resporise m p l . i t u d e 3 could be i d e n t i f i e d . Sequences with 19, 63, 127, and 511. bits per sequence were used. As wiI.1. b e s h a m belos\., t h i s type of t e s t ~rorkedq u i t e s a t i s f a c t o r i b .

465 3rw, and L Nw.

S i n g l e r e a c t i v i t y pulse teo-Ls VTere a l s o ~ u n ,b u t the r e s u l t i n g t r a n s i e n t s were inadequate for frequency response analy;:;ia. Since t h e s i g r i a l s t r e n g t h of a s l n g l e pulse i s d i s t r i b u t e d contin.uoinsly over a wide freqiiency range, p u l s e t e s t s r e q u i r e a, coniparatively. low-no3.se sigiyal. The lov-frequency l o a d pert,ur'oa.tioiis seen ai; l o v power reihced. t h e s i g n a l to-rmise r a t i o t o 8x1 unacceptable value in t h e frequency range o f inl;er=.st (0.002 to 1 r a d i a n / s e c ) . Rilse and s t e p response t e s t s are planned at Ziigher power levc:ls, where tlze conditions s h o u l d be :more f a v o r a b l e

The pseudorandom b i n a r y r e a c t i v i t y i n p u t r e q u i r e d a very- p r e c i s e l y c o n t r o l l e d s e r i e s of regu.l.atring rod i n s e r t i o n s a.nd witild.rawa1-s . Since t h e frequency range of i n t e r e s t w a s f r o m about 0.002 -to 1 . 0 rad.ian/sec, the rod jogger? w a s designed s o t h a t sequences with a b i t t i m e o f 3 t o 5 sec could be run for- as 1 . o q as 3. hr. The rod jogger system, whi.ch r e qii-iired no special-purpose hardware consisted of a hybrid computer cont1-011er shown scheni.atl.ca3.ly i.n Fig. 1.4= The por-taiI1e FAI-TR-2.0 analog computer vas used t o con-Lrol. t h e bri.t trim? and t h e rod d1.i.v-e motor "on" t-inies f o r t h e jn s e r t and withdraw coimiian3s. 'The MSRE d i g i t a l compu'Ler ed 'IO C O J I % Y O ~ . t h e sequencing of the p l s e train by means of a s h i f t - r e g i s t e r algorithm. 'The number of b i t s i n 'LIE sequence could 'ue varj.eCI over a range between 3 and 33,554,4..31b5.ts.

The r o d jogger sys~t'iriperformpii extremely well; as i L vas a h l e t o p o s i i i o n t h e rod with an accuracy of about iO.01 ir. (correspondillg t o i0e0005$6k/k) ou1 of 112 i n . peak-to-peak rod t r a v e l for over 500 i n s e r t - u i t h d r a w operations.

i n e anal-og computer i ~ a ?a l s o use6 t o amplify and f i l t e r t h e rodp o s i t i o n 2nd power-level s i g n a l s p r i o r to d i g j Li zinti;. Throughout t h e ni

ORNL-OTlG

PORTABI F A N A L O G COMPUTEH

r-------I EAI-TH-jc)

, I

66-4763

M S R E DIGITAL COMPUTER

.............

__ ...........

BR-~340

.....................

B I N A R Y SEQUENCE COMPUTATION

I I

I .....

DIGITIZER AND AND FILTERING SIGN A L ~

I 1

RECORDER

.....................

REACrOR

F i g . 1.4.. Block Dri.agram of MSRE Hod Joggins a n d Data Logging s y s t e m for Pseudorandom Binary K e a c t i v t t y Input Tests

1'7 aynamic t e s t s t h e MSRE computer W R S used i n ,the f a s t scan mode t o d i g i - t i z e and store t h e d a t a on :rfEig;netic -tape a t a sampling r a t e or" 4 per secollll. A t y p i c a l p l o t of t h e r e a c t o r power level f l u c t u a t i o n s during a pseudorandom i n p u t t e s t i s shown i n F i g . 1.5, wfiere t h e p o i n t s were taken Ti-om t h e &ERE coiiiputer d i g i t i z e d record of t b e t e s t .

Anelysi s Procedures T'he t e s t data were analyzed u-sing two independent d.i.gita.1 computer in.et1iod.s. T h i s d u p l i c a t i o n w a s done as a, check on t h e ana1ysi.s procedures. T'ne " d i r e c t method" used a d i g i t a l f i l t e r i n g techniq7x t o o b t a i n t h e s p e c t r a l density of t h e input and t h e cross s p e c t r a l d.ensity o f t h e i n p u t and t h e outpint. The Precpxncy response of t h e system 8.t some f r e quency i s t h e r a t i o of t h e cross s p e c t r a l density t o the i.npui s p e c t r a l rleiisity a t t h e frequency. It i s necessayy .t;hat r"rcc1inencics s e l e c t e d for a n a l y s i s be harmonic fregixencies since the i n p u t signal. i s p e r i o d i c 'The "indirect method" recplred a cal.eulation of t h e ai.ntocoi-reI.atri.on fi.inci;iol-i of the i n p u t and -the cross correlation f u n c t i o n of the i n p u t and the output. Subseqinent F o u r i e r a n a l g s i s of these c o r r e l a t i o n f ~ m c t i o n sga-ve t h e Lnpuk s p e c t r a l dengity and .the cross s p e c t r a l . d e n s i t y . These were then used t o give .the frequency respon.se as i n .the dii-ect-method m a l y s i s Roi;h me-th0d.s gave e s s e n t i a l l y t h e sane results. e

-1

3 7 -

LD L

en'

4.17

8.34

12 51

t 7.09

21.26

TIME ( 3 0 - m i n FULL S C A L E )

Fig. 1.5. Nuclear Power w i t h N o = 465 kw.

2543

29.60

T i m e for 5 1 l . - R i t Pseudorandom Seqi~ence

Results

The r e s u l t s of 'clie P.ISRE fxqinency response t c o - t s for power l - e v e l ~ up t o 1 bbi a r e shown i n Figs. 1 . 6 t o 1.13, along with. previously published t h e o r e t i c a l predic-Lions 'The experimental results i n d i c a t e a c o n s t s t tent1.y ].owel- magnitude r a L i o f o r ( G N / N o ) / (6k/ko 1 t h a n t h e t h e o r e t i c a l p r e d i c t i o n s a t a3.I frequencies and a,?; 31.1. power I-evels. However, t h e shapes of t h e experimental curves c l e a r l y are consj-stent with p r e d i c t i o n s . Work i s now i n progress t o deterrnine t h e reasons â&#x201A;Źor t h e d i f f e r e n c e s . Fortunately, t h e t h e o r e t i c a l work i n ref. 3 I.ncI.uuded c a l c u l a t i o n s of tile s e n s i t i v i t y of t h e freque-ncy response to chail.s;es i n numerous system parameters. T h i s iiiformati.on i s proving t o be valuable i n e s tab].. which system parameters t o suspect as -responsibk f o r t h e d i s c r e p m c i e s a

E a r l y work suggests t h a t t h e zero-power d i s c r e p a n c i e s are due t o t h e effec-L of fuel-salt pl-enums above and below t h e c o r e . These regions i n c r e a s e t h e z f f e c t i - v e volume of t h e core. An i n c r e a s e of 1;he e f f e c t i v e core volixne t o include one.--third of t h e upper and lover plenums i n t h e -Liieoretical. model. gives agreement with experimen~tal.r e s u l ~ t s

The at-power t h e o r e t i c a l results obtained with t h e i n c r e a s e d ef-f e c t i v e core volime agre? with experimental r e s u l t s a t hi.giier frequencies f o r t h e at-power runs, b u t t h e d i s c r e p a n c l e s i n magnitude raLLo remarih a t low frequeiici-es around t h e peak. The computed sensri-tivities indica-Le t h a t the frequency response i n t h i s range i s most s e n s i t i v e t o power levell., No, f u e l temperature c o e f f i c i e n t oâ&#x201A;Ź r e a c t i v i t y , a_, and r u e 1 heat capaci-ty, (PIC )

Fur tliermore, t h e system equations indica-Le t h a , t t h e s e

2 102

0.00f

0002

0.005

001

0.02

0.05

FREQUENCY ( radlans / s e c

0.4

0.5

1.0

19 0

1- I

ORNI.--DWG 56-9766 . ...........

__ ___

I I

6 3 - b i t SEQUENCE --INDIRECT 4NALYSIS 0 63-bit SEQUENCE

-10

- -20 Cn

2 -30 .Id

2I -40 Q

-50

I I1

-EO -70 0.01

I I I I I I I 0.5

0.1 0.2 0.05 FREQIJENCY ( r a d i a n s / s e c )

0.02

F i g . 1.7. Frequency Besponse 100 w with F u e l C i r c u l a t i n g .

Phase of (GN/No)/(Gk/=o)

f o r No =

OSNL-DWG 66-4767

0001

0002

0005

001

002

005

i.0

FREQUENCY (radisns/sec)

Fig. 1.8. Frequency Response fox N o = 75 kw.

Magnitude R a t i o of (SN/Bo>

FREQUENCY (radlons /set)

Fig. 1.9. Frequency Response

7.5 Jsw.

-1

for N o

L'hase of (GN/Do)/(Gk/ko)

1 1 1 1 1 1

CASE S R B - 4 6 5 k w - ; O

(SAMPLING IN I L H V A L = l C s o c )

- I - ' ,02 L

0001

l , l 0002

GOO5

, ,

001

002 005 0' FREQUENCY ( r o d i a n s / s e c )

h ' t g - 1..1.0. Frequency Response for No = 465 hw.

0 2

0 5

Magnitude Ratio o f

(&N/No)/(Gk/ko)

2 1.

50 40

30 20

-rn -$ $

0 -10

-20

-30 -40

- 50 -GO

- 70

0001

0002

0005

0OI 002 005 01 FREQIJENCY (radiins/sec)

Fig. 1.11. Frecpency Response 465 kw.

- Phase

of (GN/lIo)/(Gk/ku)

....,....,

for

O K N L - D W G 66-4771 , - - T r ~ r -

(CASE SRR-1 Mw-!!) S I I - b l t SEQUENCE-INDIRECT ANA!.YSIS B l l - b l t SEQIJENCE -DIRECT ANALYSIS

(CASE SRR -! M W- - I % ) 7 - - b 1 t SEQUENCE-INDIRECT LiNALYSIS 7 - b i t SEQUENCE-DIRECT ANAL'ISIS

SblvlPLlNF INTERVALE :

INDIRECT ANALYSIS - 1 sec IRECT ANALYSIS-0.25 sec

0.Wl

0.002

QC05

0.01

0.02

0.05

0.1

0.2

0.5

1.0

FSEQUENCY( r a d i n n s / s e c )

F i g . 1.12. Frequency Resporise

Tor N o

= 1.0 MW.

Yagnitude Ratio of (bN/No)/(Gk/ko)

22 90

ORNL-DWG 6 6 - 4 7 7 2

C A S E SRB - 4 M W- 11

50 a, OI

2 LIJ

-7

511- blt SEQUENCE - I N D l R E C r A N A L Y S I S 541 - btt SFQUENCE - DIRECT A N A L Y S I S C A S F SRB-f Mw-12 1 2 1 - b l t S E Q U E N C F - DIRECT A N A L Y S I S

lNDlRF\"T A N 4 L Y S I S

SAMPLING INTE4VALS

DIRECT A N A L Y S I S

0005

001

002

FREQUENCY

F i g . 1.13. 1.0 N.7.

-4

sec

-0 2 5 sec

0002

I-

S4MPLlNG INTtHVALS

0001

Freqii.ency Response

005

(radians/sec)

Phase o f (6N/No)/(6k/ko)

for No =

parameters appear as a. q u a n t i t y NO^ /(MC ) It w a s fouiici t l m t e x c e ~ . ~ . e n t f p I"' agreement be-iween t h e o r e t i c a l and experimental r e s u l t s may be obtained a t a1.l freqinencies and all t h r e e power l z v e l n if', j-n t h e t h z o r e t i c a l calcu1-ations, t h e i n c r e a s e d e f f e c t i v e core volvme i s used and. t h e quanti.ty N O " ~ / ( K C ~ )i~s i n c r e a s e d by a f a c t o r of 1 . 5 t o 2. The p l a u s i b i l i t y of such changes ris now being e x 8 ~ i i n e d .

In o r d e r t o g e t a more axcurate e s t i m a t e of the f u e l tewtperature c o e f f i c i e n t of r e a c t i v i t y , t h e hot-slug t r a n s i e n t t e s t as reported. e a r l i e r 5 was modified and r e r u n i n January 1966. li1 t h i s t e s t t h e r e a c t o r power l e v e l w a s c o n t r o l l e d by tlie f l u x servo a t 100 w w i t h . t h e fuel l o o p c i r c u l a t i n g ani3 tile coolant loop stagnant. A f t e r h e a t i n g t h e stagnant coolanl:, sa1.t about 20째F h o t t e r t h a n t h e f u e l sal.!;, t h e coolant pump w a s s t a r t e d , produci.n.g a hot s l u g of fu.el. i.n t h e h e a t exchanger which w a s subsequently- inbi-oduced i n t o t h e core. I n t h i s t e s t , then, t h e chan.& i n r e a c t i v i t y was due e n t i r e l y t o t h e change in. temperature, and. t h e rod-induced reactri-vj~tyr e q u i r e d t o keep t h e r e a c t o r cri.t-j.cal v a s approxj~mate1.y equal and opposite t o t h a t due t o t h e f u e l and g r a p h i t e temperal;u.re change. Since tlie gyapbrite responds slowly t o changes i n fuel temperature, t h e h.niedia'ie e f f e c t s on r e a c t i v i t y can be a t t r i b u t e d t o the f u e l temperature c o e f f i c i e n t alone. F u r t h e r c o r r e c t i o n s h.ave y e t

23 O R N L - D I G 66-4773

-1

0004

9-REGION CORE MODEL EXPERIMFNTAC SESULTS F R O M HOT-SLUG TEST USING SAMULON'S ME rtioo, SAMPL ING INTERVAL 2

0002

0005

001

002

005

FREUUFNCY (radians /set)

Fig. 1.14. Frequency Response - Magnitude R a t i o of Reactor Outlet Teniperature Response t o Inlet Temperature P e r t u r b a t i o n s

t o be a p p l i e d t o t h e r e s u l t s OP the t e s t , b u t a preliminary c s t i n n t e of -4.7 X loH5 has been o'otained. 'Piis compares favorably with the (OF)-' used i n t h e t h e o r e t i c a l calcup r e d i c t e d value of -4.84 X lat,ions.

The t r a n s f e r f u n c t i o n of r e a c t o r o u t l e t temperature response t o chenges i n r e a c t o r i n l e t -Lempei-aL.u.re was al.so c a l c u l a t e d from this test, and t h e p l o t of :magnitud.e r a t i o vs frequency i s shown i n F i g . 1.14, Note t h a t t h e experimental cu.rve i n d i c a t e s much g r e a t e r attenuation. over most of the frequency range shown. This i s proba1il.y due t o 'nigher-than-eupeeted rates of heat transfer t o t h e graphi-be, since experimental mlixing studies3 i n d i c a t e d t h a t t h e r e i s very l i t t l e a t t e n u a t i o n d:ue t o mixing Reasons f o r t h i s discrepmcy i n t h e frequency range below 0 . 1 radian/sec are being studied.

Svstems Perforrnmice Off-Gas

System

Some d i f f i c u l t ; y wiYn plugging and p a r t i a l r e s t r i c t i o n s i n -the MSKE o f f - g a s systems has been encountered a t v a r i o u s t i m e s i n the o p e r a t i o n of the r e a c t o r systems. In t h e p a s t t h e s e o b s t r u c t i o n s have developed a t i n - l i n e f i l t e r s and. p r e s s u r e - c o n t r o l v a l v e s with e x t r e n d y small f l o w p a s s a g e s . During early o p e r a t i o n s , .the p1uggiri.g of fil-ters %7asx b t r i b t d e d t o having f i l t e r s with inad.eqm;zte f l o w areas t o accoizlvaGdate t h e m a t e r i a l t o be removed from t h e gas s t r e a r i s . (For exrmple, t h e orj-ginal. f i l t e r i n the c o o l a n t off-gas l i n e , 528, w a s a t u b u l a r element only 1 i n . long by 1/2 in. i n diameter.) The plugging of valves appeared to be a r e sult of : f i l t e r s which were t o o c o a r s e t o remove i d J . t h e pariiicles t h a t w e r e capable of causing pli-xgs. During shutdown w h i c h followed t h e zero-power experiments (run- 31, larger f i l t e r s , capa'ol-e of remo7rin.g p a r t i c l e s g r e a t e r t h a n 1 p i n d i m e t e r , were i n s t a l l e d ahead of the p r e s s w e - c o n t r o l v a l v e s %in l-,oYi t h e

24 f u e l aiid coolant; off-gas l i n e s The fuel-system p r e s s i r e - c o n t r o l valve (PCV 5221, which had e x h i b i t e d some e r r a t i c behavior i n rm. 3, w a s t e s t e d and feud t o have t h e same pressure-drop c h a r a c t e r i s t i c s t h a t it ha& when fri.rst i n s t a l l e d . 7kj.s valve w a s r e i n s t a l l c d f o r the ilex% o p e r a t i o n of ’ihe r e a c t o r . No fw-Lher d i f f i c u l t i e s were encouxtered wiLh the cool-ant off-gas systzrn, b u t s e v e r a l p r o b l e m developed i n t h e fuel. sysLern. (See Fig. 1.15 f o r a s i m p l i f i e d flowsheet of the fuel off-gas system.)

The performance of the fuel off-gas system w a s s a t i s f a c - t o r y during datlion o f the reactor i n t h e s u b c r i t i c a l aid low-power (up t o 25 k r ~ ) op*>Deceinber 1965 and January 1.966. The f i r s t , i n d i c a t i o n of CLifLricu.l.ty i n t h i s rim (run 4.1 occurred 011 Jan.uary 23 w i L h the r e a c t o r power a b 500 hw. The t o t a l integrated. power accuuiulated iip t o t h i s tiroe w a s about 3 Mwhr. At tt:i.a,t time t h e system p r e s s u r e began. t o r 5 s e slowly, i n d i c a t i n g e i t h e r a r e s t r i c t i o n ?.-at h e v i c i n i t y of PCV 522 or a malfwlctri.on of t h e v a l v e . (A r o u t i n e check of system p r e s s u r e i n t e r l o c k s on t h e previous day had i n d i c a t e d noma]. behavior of a l l . components. S h o r t l y a f t e r t h e start of t h i s p r e s s u r e t r a n s i e n t , t h e resi3onse of t h e draiii-tank p r e s s u r e s i n d i c a t e d an abnormal r e s t r j - c t i a n a t a capri.l.l.ary f l o w r e s t r i c - L o r in l i n e 521., the f u e l - l o o p - t o - d r a i n - t a n k p r e s s u r e e q u a l i z i n g l i n e . The excess p r e s s i x e i n t h e fuel. system w a s r e l i e v e d by v e n t i n g sas t’nrough HCV 533 t o the a u i l - i a r y c h a r c o a l bed. imti.1- t h e r e s t r i c t i o n a t PCV 522 w a s c l e a r e d by o p e r a t i n g t h e valve s e v e r a l times through itx P u l l s t r o k e . Thesz opera-

ORNL-DWG

F R O M COOLaN S Y S T E M OND SOT1i OIL SYS

v-2

v-3

...................

Pig - 1.1.5

CHARCOAL BED

S i m p l i f i e d Fl-o~wsheetof

MSm

....................

Fuel- O f f -Gas System.

66-24121

t,ions d s o r e v e a l e d si; leas%a. pa.d?:.aII_ rcs%r.ic;tion i r i t h e l i n e t o t h e Yke reactor W ~ imde S sub,2~qiLhp cha,rcoal ~ bed, a;pparexLLy ut HCV ,533 c r i t i c a l a f t e r &l/% hr operation a t 500 kw.. S a t i s f a c t o r y pressin-e c o n t r o l nra,in%a.ioed for abl;)l& 24 hr 'out t h e plugging a t HCV 522 r e c u r r e d s h o r t l y xf%e:~t h e reaCL<iT power was raised to l Pb. Again, t h e o p e r a t i o n of -this valve t'mougti it6 fu.i_!.. s t r o k e ' w a s e f f e c t i v e i n r e l i e v i n g a t l e a s t p a r t of the r e s t r i c t i o n . However, on this occasion, evidence of res-trictiiom at -the charcoal-bed i n l e t s began t o appear. These r e s t r i c t i o n s were 'oypassed by putting t h e two spare charccal-bed s e c t i m s (24axid 233) i r i s e r v i c e axd cLcss;i~ig t h e i n l e t valves to the two t l ~ a . twere r e s t r i c t e d (1-4a d U ) Within a,bout 6 iir t h e i n l e t s of beds 2% and 233 a l s o plwged. When t h e prev i o u s l y plugged beds v e r e checked, at least one was fowitl t o be c l e a r and off-gas f l o v was reestablished- through bed D. The jcmiTpulation of t h e charcoal-bed inlet valves revealed s u b s t a n t i a l rnec1~a;riieal.d i f f i e z i l t i e s with. t h e manual o p e r a t o r s . These were caused by misaligrment of extansion handles and c o r r o s i o n due t o wea,ther exposilre md. r e s u l t e d in two of t h e valves becoxxing i n o p e r a t i v e .

The combination of c t i f f i c u l t l e s in the off-gas system r e s u l t e d I n a r e a c t o r shutdown t o c o r r e c t the c o n d i t i o n s . The r e s t r : i c t i o r j s i n the equ alizin g l i n e (521) arid t h e a u x i l i a r y verrt l i n e (533) se ere re.Li.evea by r e m o v i q t h e c a p i l l a r y (FE 521) arid a check valve (CV 533) respectively. The valve and f i l t e r assembly, and a second valve t h a t had 'beeri t r i e d b r i e f l y , were removed from l i n e 522. 'The o r i g i n a l valve and the fril-ber were subsequently subjected to deta5.1ed exzminations which are described i n "Component Development, " t h i s r e p o r t . Pressure-drop measurements showed a higher pressme &OXI by a f a c t o r of 3 to 4 i r i tire valve and a f a c t o r of l 0 i n the f i l t e r . EIowevcr, t h e observed. r e s t r i c t i o n s , p u r - t i e u l a r l y i n -&e case of t h e filter, were not high enough. t o accoimt f o r the observed pressure behavior i n t h e operating system.

While t h e r e a c t o r was shut down, s e v e r a l mneasuxementc were rmde of t h e p r e s s u r e drop across i.ndividml sec-tions cf t h e charcoal. beds. Measurements made s h o r t l y a f t e r tne shutdomi showed e s aerxt;ia.ll.y noma1 p r e s s u r e drops f o r three of t'ne f o u r sec'cions. The pressure ikop a c r o s s the fourth s e c t i o n (IB)w a s about 6@ higher t h a n tha-1; acrcss the a t h e r s . (These measurements incI.ude t h e presstlre &ups a c r o s s the i n L e % and ointl e t valves of each bed s e c t i o n . ) KLthough no%hing was done .to c o r r e c t t h i s condition, measmemerits made just 'before t h e next s-kartu9 (run 5) showed %hat all. Pour s e c t i o n s had essentially identical., n o m 1 pressme d r o p s . Mechanical. r e p a i r s had been rmde to %he operating rflechai?ism o f t h e valves, b u t these d i d not a f f e c t t h e f l o w c h a r a c t e r i s l j c s . Measixe-cnents were also made of t h e pressure drop across t h e ailxiliazy c'narcoal 'oed; no abnormalities were observed t h e r e .

The preparations f o r t h e next s t a r t u p fruAuded i n s t a l l a t i o n of a Large, r e l a t i v e l y coarse (50-y) f i l t e r a i d a Large, open hand valve a t t h e PCV 522 Location. This a r r a n g e m n t eliminated tine srrmll, e a s i l y plugged passages a s s o c i a t e d with PCV 522, and it appeared t h z t t h e filter would s t i l l remove any p a r t i c l e s l a r g e enough to plug valve 52213, which was bo be used f o r sya-tem pressure c o n t r o l . ( S a t i s f a c t o r y nianual pressure c o n t r o l using valve 52213 had been demons-t;ra,ted during the shutdown.)

26 I n the next; opera%.i-onof t h e f u e l loop (run 51, f u e l s a l t w a s c i r cirl.ated for /A. hr w t t h t h e r e a c t o r sii'ucr.i.tica1. o r a t very l o w p m e r (LOO w ) before t h e power was r a i s e d . The evid-ence j.s not concl.usj.we, b u t t h e r e w a s some rind-icatioii o f an i n c r e a s e i n . B l o w r e s i s t a n c c a t valve 522B diuring t h i s t i m e . S h o r t l y a f t e r %he power was raised- t o 1- tvlw, t h e i n c r e a s e i n f 1 . o ~resis-Lance at 527B accel.erated sharply. Frequent ad justment o f t h e valve w a s required. to maintain reasonable prep c* D U Y c o n t r o l , The r e s - t r i cL i o n st t h e c h a r c o a l beds which occixred. a f t e r one such adjustment dcveloped q u i t e r a p i d l y and res,ull;ed i i i aljmast cornpl-ete plugging of t h e two beds t h a t were j.n s e r v i c e (IA and D ) . A f t e r the rca,ctor *sin, which w a s requi.:red because of t h e f a i l u r e of t h e space-cooler mo-t;orj 5.t w a s debenrilimd th.% the a u x i l i a r y c h a r c o a l bed w a s also r e s t r i c t e d . ThLs bed comes i n - k s e r v l c e autcr:,na.ticall.y during a &rail1as a backuq t o r e l i e v e any excess gas p r e s s u r e . 'Ihe helfion Ln t h e f u e l sys-Lem was t h e n r e l e a s e d Lhrough the two standby c h a r c o a l beds. 0

l)etsil.ed i n v e s t i g a t i o n s a f t e r t h e shutdown showed -that t h e cha.rcoa1bed r e s t r i c t i o n s were proisably a t t h e i.nl.eS, ,v-a.lves. Valve 62.1,t h e i n let valve t o bed LB, w a s removed f o r zxaminaLion i n t h e TWIGL. The r e sults of t'nese examinxtions a r e d e s c r i b e d i.n t h e s e c t i o n e n t - i t l e d "Component Development." The p r e s s u r e drop a c r o s s bed- lB w i t h valve 621 i n p l a c e w a s very much higli-er t h a n normal. With %he valve out, t h e pressure drop w a s mucb I m e r bui; still h i g h e r t h a n for a normal, u n r e s t r i c t e d bed.. An excess of helium was t h e n f o r c e d through t h e bed. f o r a few minu-Les, and tile p r e s s u r e drop suddenl-y decreased. Subsequeni; pressure-drop measurements wider c o n t r o l l e d c o n d i t i o n s gave values wh.ich were i i o m l f o r an u n r e s t r i c t e d bed. S e v e r a l gas samples ~wemtaken from.%he f u e l l o o p during this shut-, down i n a n e f f o r t -Lo idefitjfy some of t h e plugging c o n s t i t u e n t s . For s e v e r a l days afkr t h e d r a i n , a l l hel.iiim f 1 . o ~ through t h e fuel system was stopped, and t h e helium i n t h e loop was circu.la$ed a t -1.1.00"F. The heKim i.n t h e off- g a s holdup volume (170 l i t e r s 1 was s t a y a a n t a t about 122째F. Three si~.ccessi.vep a i r s of samples were t h e n t r a p p e d from t h e d.ischarge of t h e holdup volume; each p a i r of s m p l e t.ca.ps consisted. of a p i p e c o i l a t I.iqii.id-nitrogen temperatiire foLlowed by a U--tu'ue f i l l e d w i t h rno1ecula.s s i e v e material-, a l s o a t l i q i d d - i i i t r o g e n temperature. 'i'he f i r s t p a i r of sampl.es was i s o l a t e d - from t h e gas thai; had been i n the hoMup volume by dlspl-acj-ng it through the t r a p s wI.t'n hel-iurri from t h e f u e l l o o p . The helium which e n t e r e d t h e holdup v o l m e dixrtng th5.s displ_a.cement hias presumed t o be r e p r e s e n t a t i v e o f t h e m t c r i a l c i r c u l a t b g j.n. t h e l o o p . A second. dri-spl-acement through another p a l r o f t r a p s was used to i s o l - a t e m a t e r i a l from 'cina-t; g a s . For t h e . t h i r d p a i r of sampJ-es , t h e r e ac'car cel.1- temperature was a.l.l.owed. t o r i s e t o h e a t t h e o f f -gas h o l d q volume t o 173째F b e f o r e t h e gas was passed through t h e t r a p s . The purpose of t h i s w a s t o s e e i f any additional.. ma-Lerial., was r e l e a s e d f r o m t h e holdup volume by i;he i n c r e a s e i n temperature. Ana,I.ysj.s of t h e samples has not y e t been completed because of t h e high a c t i v i L y associated w i t h .L_

b m m 7

Since p a r t i c u l a t e m a t t e r o r i g i n a t i n g at l;he f u e l puap was regarded as one possi'ole cause of' plugging i l l ti?e off-gas system, t h e main fuel off-gas l i n e (522) was opened a t $pic! fuel.,pixtip for visual. i n s p e c t i o n . Srnall. .amounts of gray-green powdery m a t e r i a l were found be-tween the Paces

2'7

of t h e flariges t h a t were opened, b u t 1x0 deyosi'r,~were seen i n . t h e p r t , of t h e h.~l.chijpvolume tha-b couid be i n s p e c t e d . Samples of -the s o l i d mit e r i a l a : d swabs OS t h e holdup v d u a e were removed for a n a l y s i s . !idcIitiori;z_i_ work t o b e p e r f o m e d b e f o ~t h e next star'tv.p inclndes :

1. a blmoirrt of tlne holdup ~ o l t u n ei;o remow any l o o s e n&eriul,

2. design, fabric,.;tion,

and instal.l.ation of a n e w fiI.te.~-cc7ri~1"01.-7,'al.ve asserribly a t PCV 522, arid

replacement of s e v e r a l v a l v e s i n -the system w i t h valves haxirig larger t r i m*

SaLk-Pwnu Oil Xvsteiris Elrrtrairied gas i n t h e c i r c u l - s t i n g o i i tend;; t o accuinu1.ate i n t h e v o l u t e 02 t h e s t a n i b y o i l p.ur~p. Frari t l i e begirming of MSX3 per at ion, i - L ; was n e c e s s a i y t o prime t h e standby pump Trequently t o keep it ready f o r o p e r a t i o n . (Priming was done r o u t i n e l y once a s h i f t . 1 Observations i n a devel.opiiient loop showed thab entrairmenrt and frothing i n t h i 2 rese r v o i r were due t o t h e a c t i o n of a j e t pump u s e d t o scavenge oil from t h e h e a r i n g housing (using shield- p l u g oil. flow t o dxive t h e j e t ) aiid a g i t a t i o n of o i l . by t h e s h a f t and b e a r i n g s . 6 In September 1965, the j e t s on t h e fuel .znd c o o l a n t pimps were r e p l a c e d with less powerful j e t s to decrease entrttim-ent After this m o d i f i c a t i o n , it was p o s s i b l e to r e duce t h e frequency of priming t h e standby p w q t o once a. veek i n t h e fuel. o i l system; on the coolant, lu-be o i l system i-t was necessary t o continue a s before. e

Aster t h e ; j e t s were changed it w a s foixid ,t;i?at changes i n fuel-pmrIp b e . s r i n g - o i l f l o ~or r e s e r v o i r p r e s s u r e caused changes i n r e s e m o i r l e v e l , appa,rently because of holdup of oil in t'ne salt-pump motor cw'l.ty. Oil from t h e b e a r i n g housing can enter t h e motor c a v i t y e i t h e r by leakaye p a s t the upller s e a 1 o r through a passage connecting t h e motor cairity t o t h e area between .the two s h a f t b e a r i n g s . Apparently a.n excess of flow t o t h e bearjag housing causes o i l t o be forced up i n t o t h e motor c a v i t y . Alkhougki the breather l i n e a f f o r d s a r e t u r n t o t h e oil- reservoir, it has been found t h a t once t h e oil c o l l c c - t i o n begins i n t h e motor cav-ity it i x w l l y cuntinues u n t i l - e i t h e r t h e oil system i s shut down completely o r t h e b e a r i n g flow i s reduced -Go below normal. An i n c r e a s e i n o i l flow - t o t h e b e a r i n g housing f r l s m the normal 4 @E t o 5 gpm causes a. l e v e l dec r e a s e i n t h e oil. r e s e r v o i r OS over 2 g a l . (Much more t h a n t h i s e o u l d co.lf_ect without reaching tlk motor, but normalljr- a c t i o n is t a k e n t o stop c o l l e c t i o n at l-ess t h a n a gal-lon.)

Leakage p a s t t h e lower seal drains t u t h e oil catch t a n k , vhich i s equipped wi'c'n a l e v e l indica-torand which is p e r i o d i c a l l y d r a i n e d t o t h e w a s t e oil r e c e i v e r . A f t e r t h e instal.l.ation m d c a l i b r a t i o n of a siphon tube in t h e fuel-purfp o i l c a t c h t a d & in November, o i l was n o t added t o b r i n g t h e l e v e l indicator on s c a l e . The f u e l - p u p Lower-seal l e a k rate ciuring t h e months of December and January i s t h e r e f o r e not know-n p r e cisely. However, when o i l w a s d e l i b e r a t e l y added t o t h e oil. catch t a n k

28 i n February, it took 900 cc t o b r i n g t h e l e v e l insti-mteiii; on s c a l e . Tne s e a l leakage e v i d e n t l y had been very low, because tihis volume I s very neair t h a t calcul-atcd t o .fill. -Wie empty pipe from Lhe oil. catch t a n k Lo t h e d r a i n valve at Lhe waste o i l r e c e i v e r . After t h e oil c a t c h t a n k level. i n d i c a t o r w a s br0ugh.L on s c a l e , t h e i n d i c a t e d l r a k r a t e w a s approximately 2 cc/day. The coolant--sal%-pump lower-seal leakage measured dmiiig J a n m r y and most of February w a s zero. Near thc. end. of Pebru.a.i?y- a l e a k r a t e of approxima,t,el_y I+ cc/day began. The 1eveI.s i n -the o i l r e s e r v o i r s a r e recorded rouLineI-y once a s h i f t . A s was seen above, .the amomLs of o i l h e l d up i n ?;he T . O t Q r c a v i t i e s vary w i t h . operating conditions, and these caizse v a r i a % i o n s i n txe o i l r e s e r v o i r s . A u t t h e r e has been no reason why t h i s v a r i a b l e holdup should show any long-term t r e n d . Therefore t i e reservoir l e v e l s recorded over a perri.od of weeks should. r e v e a l changes i n oil i n v e n t o r i e s . Figure 1.16 i s a p l o i of the fuel-pump oil r e s e r v o i r l e v e l s f r o i n December 1.965 through February 1966, when t h e o i l system w a s j.iI contiuuous operst i o n . It i.s apparent tliai; leakage w a s l e s s than can be ineasured by t h i s method. The coolant-plinrp o i l r e s e r v o i r Level showed similar behavior except t h a t t h e f 1u.ctua'i;ion-s were smal.l.er (probably reflec-tirig less motoi"c a v i t y holdup). J ?

'Treated Cooling-Water System

'The trea-Led-wa-ter system i s a c l o s e d systenl removing h e a t from t h e -thermal shield and o t h e r i t e m i n t h e r e a c t o r and d r a i n c e l l s . Problems

ORNL

DWG 66 -3524

.d..

-s-"

I liter

(I%=

1.19 liter1

> W J 60 0

20 DEC

i I

20 JAbI

20 FEB

F i g . 1.16. P'iie?.-Pump Oil-Reservoir Level i n Xujns 4 and 5.

encountered during t'nis report p e r i o d were neutron a c t i v a t i o n of t h e corthrough t h e thermal s h i e l d r o s i o n i n h i b i t o r and i n t e r r u p t i o n s of FLO'GJ slides.

A c t i v a t i o n . During power operation i n run Li., induced a c t i v i t y i n t h e t r e a t e d water r o s e to an unexpectedly high l e v e l . Extrapolation of observed r a d i a t i o n Levels i n d i c a t e d t h a t - at 10 M w , g m . m r a d i a t i o n near t h e h e a t exchanger iri t h e d i e s e l room wou_l.d be about 400 mr/hr; s i m i l a r l e v e l s woi-ild e x i s t i n t h e water room. 'fie a c t i v i t y proved- to be 12.4-kr "K produced i n t h e corrosion i n h i b i t o r (2000 ypm of a 75$ potassium n i t r i t e , 25% potassium t e t r a b o r a t e m i x t u r e ) , The l e v e l indica%ed t h a t t h e average f l u x i n t h e system (about 80$ of which i s included i n t h e .Wierm;zl shield) vas equivalent t o about 7 X ' 0 1 thermal neutrons sec-' a t 1.0Mw.

A sixcvey o f p o s s i b l e c a t i o n replacements f o r potassium led t o t h e choice of l i t h i m i , h i g h l y enriched i n t h e 7 L i i s o t o p e t o minimize t r i t i w a production. An adequate m o u x t 0% Lithium n i t r i t e s o l u t i o n was prepared corrrrmercially by i o n exchange from potassiwn n i t r i t e and l i t h i u m hydroxide. A f k e r t h e 4000-gal t r e a t e d - w a t e r systern vas d i l u t e d with demirieralized water to reduce the potassium from 800 t o 3 ppm, t h e d e s i r e d i n h i b i t o r c o n c e n t r a t i o n was attai.ned by adding 7 L i n i t r i t e , b o r i c a c i d , and 7 L i hydroxide. When t h e r e a c t o r w a s next operated a t power, in run 5, objectioizaklle a c t i v a t i o n a g a i n occurred, t h i s time due t o 1.0 p p m or" s o d i m which had e v j d e n t l y ccme i n w i t h the demineralized water from t'ne OFXL f a c i l i t y . Condensate w a s produced a t t h e PISRE w i t h l e s s t h a n 0.1 ppm of S O U U ~ , and t h i s was used t o d i l u t e t h e sodium i n the t r e a t e d - w a t e r system t o 0.3 ppm. The concentrations OS sodium and 6 L i a r e now low enough so t h a t s h i e l d i n g and zero-leakage e o n t a i m e n t of t h e water system -w1.11_not be necessary. Flov Interruptions. On s e v e r a l occasioiis flow through t h e thermal. shield s l i d e s stopped. Each time it w a s found t h a t when t h e water supply l i n e was disco-mected and water was allowed t o flow backward tmcugh t h e s l i d e s , considerable m o u n t s of a i r CiXIne out wi.th t'ne water. l k e conc l l ~ ~ i owas n t h a t a i r co~iLdaccumulate i n Yne Longest slide until t h e (Th.is s h o u l d be imhead exceeded t h e p r e s s u r e avai1abl.e to cause flow. p o s s i b l e if' t h e piping i n t h e s l i d e were i n s t a l l e d a s desi-gned.) Venting t h e i n l e t l i n e r e s t o r e d t n e flow, and provisions were niade t o fac i l i t a h e v e n t i n g . ZTie source of t h e a i r w a s e v i d e n t l y a,. v o r t e x i n t h e surge talnk w h i c h occurred when t h e l e v e l was l u w . After S;he flow through thE: surge tar& was d r a s t i c a l l y red-uced (it bad been a,bov-% 30 g y m ) t h e r e was no recurrence of t h e flow i s i t e r r u p t i o n s

30 eludes . t e s t i n g of i n d i v i d u a l c1osu.l-e devices on l i n e s p e n e t r a t i n g tile ce1.1.s and p r e s s u r i z a t l o n o f t h e c e l l s for leak. bnnting and measurement of the o v e r a l l leakage rate.

A1.1.l i n e s c a r r y i n g heli.1~~1, a i r , o r water i ~ ~ tth o e c e l l s a r e equipped ei'c'ner w i t h check valves o r block valves a c t u a k d by r a d i a t i o n monitors A l l of t h e s e valves were t e s t e d , i n p l a c e wherever p o s s i b l e ; otlierwise t h e y were removed and bench-tested. Yest pressures were 20 psig or more, and leakage rates were r e q u i r e d t o meet conservative c r i t e r i a . This work was done concurrently w?:.th mmintenmce b e f o r e Yne ce1.l.s were c l o s e d .

Leaks which occurred i n t h e cooling-water system were mostly i n t h e check v a l v e s . These were t h e r e s u l t o f f o r e i g n p a r t k l e s , apparently washed out of the system and t r a p p e d between t h e s l i d i n g and movri.izg p a r t s of t h e v a l v e s . Two hard-seated valves i n tine t r e a t e d - w a t e r sys1;ern iiad t o be r e p l a c e d even though t h e s e a t s were lapped in an e f f o r t t o g e t the111 t o seal. One w a s a check valve w i t h a swinging check, i n a water l i n e between the surge t a n k and condensate tank, and t h e o t h e r was a springloaded hand valve on to;p of t h e surge t a n k , which has t o c o n t a i n a i r . 'They r e p l a c e d w i t h s o f t - s e a t e d v a l v e s . The leakage rates on watercontaining valves were determined by c o l l e c t i n g t h e leakage, and a flowmeter w a s used t o measure a i r leakage through valves on t o p of t h e s u q e tank. The m a j o r i t y of the valves i n t h e helium system of both primary and secondary containment had s a t i s f a c t t o r y Leak r a t e s . iT'hose which iiad exc e s s i v e leakage were check valves and were found t o have damaged O-rings and/or f o r e i g n p a r t i c l e s , u s u a l l y metal. chips from machininzJ i n them, A f t e r cleaning and instal.l.ing new O-ringsJ t h e y were s a t i s f a c t o r y . Many of t h e check valves had t o be removed from the syseem -Lo pressixdze them. A f t e r I*einstRlliiIg, t h e l i n e s were p r e s s u r i z e d and t h e f i t t i n g s were checked w i t h a heliwri l e a k d e t e c t o r . Leakage ra'iec t21.roi~ght h e valves were dete:Psnined by a f l o i m e t e r o r by d.isplaceinent o f watey i n a c a l i b r a t e d td'e. The i n s t r m e n t - a i r - l j . n e block valves w i t h f e w exceptions were found. t o be s a t i s f a c t o r y ; however, n-merous tube f i t t i u g s were foimd t o be l e a k i n g by checking w i t h l e a k - d e t e c t o r s o l l i t i o n when tii? l i n e s were p r e s s m i z e d t o cheek tile val.ves. Several qirick dj.sconnects on a i r l i n e s i n s i d e tile r e a c t o r c e l l and drain-tank cell were foimd. t o be leakintl; when checked w i t h l e s k - d e t e c t o r s o l u t i o n a n d were r e p a i r e d . These leaks do no-i; c o n s t i t u t e EL l e z k in secondary contairiment, si.nce each l i n e has a block valve o u t s i d e t h e cell; but a l e a k here does aâ&#x201A;Źfect the c e l l leak rate when a i r pressu-re i s on the l i n e -to operate t h e valve. The b u t t e r f l y valves i n t h e 30-in. l i n e used f o r ventri_l.ati.:ng the

eel-1s during maintenance operations were f i r s t checked by p r e s s u r i z i n g

between them. The leakage measured by a flowmeter was excessive, and t h e valves had t o be removed from t h e system t o de.f;emdae t h e cause. There was considerable di.rt on t h e rubber sea,ts, and one was c u t ; t h e s e s e a t s were cl-eaned and r e p a i r e d . We found Gila%t h e motor d r i v e uni-ts would s1ri.p on t h e i r mounting p l a t e s by a s m a l l amount, thus causimg a s l i g h t error i n Yne i-ndicated p o s i t i o n o f t h e valve. Dowels were Lns t a l - l e d i n t h e moun-LinE p l a t e s t o prevent this. Sma.1.1. l e a k s were a l s o

31 found around t h e p i n s which f a s t e n t h e b u t t e r f l y t o t h e opera,ting s h a f t ; t‘nese l e a k s were r e p a i r e d w i t h epoxy r e s i n . ‘The l i n e from t h e t;’ne-ml.S s h i e l d rup-bure d i s k s t o t h e v a p o r - c o n d e n s i q systems has X ~ ~ ~ C I - O Uthreaded saints t h a t leaked badly when p r e s s u r i z e d w i t l i n i t r o g e n . Each j o i n t w a s broken, t h e t h r e a d s were coated w i t h epoxy r e s i n , and t h e ,joint was r e made. AL1 j o i n t s were l e a k t i g h t when rechecked w i t h l e a k - d e t e c t o r solution. When c l o s i n g t h e c e l l s , a l l membrane welds were dye checked. A f t e r coinyletion of t’lie membrane weldirg, a l t e r n a t e t o p blocks were i n s t a l l e d , and t h e c e l l s were p r e s s u r i z e d t o 1p s i g t o l e & check a l l membrane welds with l e a k - d e t e c t o r s o l u t i o n . No leaks were found i n Yize welds. The rea c t o r access cover plate, which has a double O-ring seizl, was found -to be t i g h t by p r e s s u r i z i n g between t h e O-rings. With t h e c e l l s a t 1 psig, a l l p e n e t r a t i o n s , pipe j o i n t s , t i . f x f i t t i n g s , and m i n e r a l - i n s u l a t e d (MI) e l e c t r i c a l c a b l e s e a l s s u b j e c t e d Lo thi.s p r e s s u r e were checked w i t h l e a k - d e t e c t o r s o l u t i o n Nwiierous l e a k s were fourid i n tube f i t t i n g s and JXl c a b l e s e a l s , and the l e a k r a t e was about 45(3r3 ft3/day, i n d i c a t i n g a major l e a k . Many of t h e s m z l . l l e a k s were stopped by simply t i g h t e n i n g t h e threaded parts of .tine s e a l . However, t h e leak sate w a s still a7bout 4500 ft’/&iy. e

The c e l l s were t h e n p r e s s u r i z e d t o 5 p s i g , and Leak hunting con-tinued. Three large leaks were l o c a t e d : one in t h e s l e e v e of l i n e 522, t h e o f f - g a s l i n e from t h e pump bowl t o t h e carbon beds, under t h e belit house f l o o r , another i n an i n s t n m e r i t a i r l i n e t o valve RCV 523, a n d another from tine vapor-condensing system to t’ne s t e m domes and out t o t h e n o r t h equipment s e r v i c e a r e a through a, l i n e t h a t was texaporarily open. A l l p e n e t r a t i o n s , tu3e f i t t i n g s , and MI c a b l e s e a l s were again cheeked w i t h Leak-detector s o l u t i o n . k n y M I cable seaJ-s which had fiot :Leaked a t 1 p s i g were found t o be leaking, and some of -those T.i’nich had been t i g h t e n e d and s e a l e d a t 1 p s i g now k a k e d .

Tine hook gage being used t o monitor Lhe leakage r a t e a1on.g w i t h conventional p r e s s u r e gages d i d not work properly-, and the trouble wzs found t o ’oe t h e r e s u l t of extremely small 1ea.ks in t h e tube f i t t i n g s on %he reference volume s i d e of t h e system. This and t e n p x a t i x e eil.a.rtges i n the coolant drain-tank c e l l and s p e c i a l equipment room caused appre c i a b l e d i f f i c u l t y i n determining t h e le?kage r a t e . The p i p i n g t o t h e hook gage was e v e n t u a l l y replaced w i t h v f r t u l l y a l l wel.ded tiibiflg. Temsorary c l o s u r e s were put on t h e s p e c i a l equipment room, and t h e door e n t e r i c g t h e c o o l a r ~ td r a i n - t a p k c e l l was kept c l o s e d as miach 3s possible. These measures considerably- improved tlne re1ia7oilit,y of .bhe data, +

The K C c a b l e s e a l s as a growp accounted f o r a l a r g e percentage of Yne remaining l e a k s . I’Jxny were s e a l e d by t i g h t e n i n g , bu-L many of them r e q u i r e d tighteriing more t h a n once. A s a r e s u l t , s e v e r a l of Yhe gland ! d l l a r g e l e a k s were sea.1.ed. o r n u b s split ,zjd s o l d e r i n g w a s r e q u i r e d . . g r e a t l y reduced, and rmny of -bile s1m.I.l I.eaks were stopped, T o stop these and other s m a l l l e a k s which imy nod hav-e been l.oca,ted, all MI cable sea.Ls were coated with epoxy r e s i n at the s e a l s o u t s i d e oT t?re c e l l s . Teflon t a p e , used e x t e n s i v e l y on M I cab3.c seals, o,Lher tAi:ea,ded. pi.ye, and. t u b e fii;tings, d i d n o t perform s a t i s f a c t o r i l y i n providiring a g t s seal

32 A f t e r stopping o r reducing tile l e a k s i n t h e M I c a b l e seals and i n strument a i r l i n e s , t e s t i n g w a s begun a t 10, 20, and 30 p s i g . A-G t h e s e higher pressures, large l e a k s were l o c a t e d i n both component coolaut purnp dorm fl-anges by l e a k - d e t e c t o r s o l u t i o n , and one of them was a,iictible. To correc-t t h e s e l e a k s , t h e width of t h e gasket w a s reduced t o i n c r e a s e t h e 1oadi.ng p r e s s u r e 011 t'ne g a s k e t . A l l p e n e t r a t i o n s , M I cable s e a l s , tube f i i ; t i n g s , and exterrial p a r t s of valves which are p a r t of 'die s e c o n b r y containment were checked w i t h l e a k - d e t e c t o r solution a t each of t h e above pressures.

In each of t h e s e t e s t s , t h e containment system w a s pressmrized t o a s p e c i f i c pressure. Then a l l gas a d d i t i o n s and control.l.ed exhausts were stop~ped, and the l e a k r a t e was m e a s i r e d . by t h e charge i n p r e s s u r e c o r r e c t e d for changes i n 'cemperatu.re The c a l c u l a t e d Leakage r a k s are p r e s e n t e d i n Fig. 1.17.

ORNL-DWG

66-4753

ASSUMED

LINEAR RELATIONSHIP

ORIFICE FLOW

T U R B U L E N T FLOW

. ..................-

500

400

300

D "-

v) v

200

a a W

a Y

2 W

I00

z 2 z 0

---

-6

-100

-200

- 10

L A M I N A R FLOW EXPEHIMFNTAI.

DATA

CONTAINMENT PRESSURE (psig)

F i g . 1.17. Pressure Dependence of t'ne Leakage Rate of the MSFB S e ~ o n ~ ~ - ~ o n Vessel t a j . ~f o~r ~P o~s s~i btl e Flow Regimes Normalized t o the mzxinium allowabl-e leakage r a t e under MCA condihions I

Core Access O - p x ' i - ~ . Conveiiierit access -to t h e control-rod dkivcs a,nd t h e core access f l a n g e i s had.by removiiig a 4O-in.-diam plug i n a s t e e l - l i I i e d hole i i i a l o v e r s h i e l d b l o c k . Griginal-1-y a flasige on -the upper rim of the hole Lixier w a s we.lded t o the cell merdinrane, and a bol-ted, gaske-tecl cover p l a t e eorcip?_etedt h e contailmen-t; T h i s att8d,chnent,of t h e membrane t o a lower 'block p r e s e n t e d 2 pro'ulem Jrhich becnae apparent d u ing testing and which l e d -Lo rnoilification. Because of -their g r e a t wei.ght, .i;he upper blocks rriurst be :;iqported a t t h e i r ends, n o t by the l a f e r b i o c k s . To eziswe t h i s , t h e r e i s nwxssarj.1-y Some c l e a r a n c e between t h e u p p e r I?rri.en 'ul.ocks and t h e rnembrra.ne, .which nom&a.lLy 1.ies on the Lower 'olocka t h e cell.. i s p r e s s u r i z e d , t h e r e f o r e , the mmhrane L i f t s up i m t i l . it; cont a c t s tihe upper blocks. This it was f ~ e et o do everyvhere except around the access opening, where it was f a s t e n e d t o %he f k q q e " AnaLysis showedt h a t t h i s s i t u a t i o n would produce excessLve s - t r e s s e s w l ~ nt h e c:e7.1 was p r e s s u r i z e d f o r .leak t e s t i n g * Redesign of t h e liner o r f l m g e was imp r a c t i c a l . , so the rriembrane was cut loose from t h e flange and an over1apping p a t c h -was welded 011 t h e mnerribrane. T h i s patch mus-t; I ~ O Wbe CL&. off whenever access is required..

Vapor-Condensing System. Snstall.a-t;l.on of ir,strmierxtalion m d shieldon - t h e vapor-condensing system w a s co-rrrpleted., and.the system was le&-test e d before water was added. Shiel.ding corisists of earth having a m i a il-num t h i c k n e s s o f 4 f t on t o p o f t h e gas s t o r a g e tadc. This L a n k i s ,just isisride t h e area fence along t h e W T R t i C C i ? S s road, and a t least; 8 2-L; of earth 'was provided on %he road side t o give complete p m t e c t i o n $ 0 passers by mder t h e worst conditions. Before -bhe tanks were covered, d l penetrations were Iie.liLm l e a k - t e s t e d and found -Lobe t i g h t . T'nen duriqq t h e r e a c t o r c e l l leak t e s t , t h e vapor-coxidensing systen? was f_e&-i;ested at 30 psi-g and a l e a a g e sate 01"only 5.5 ft;'/ky was measired frsrm %tie 6800-Pt' system. ATter the le& t e s t , Yae m&mr-condemiinig tzs& was f i l l e d w f t l n water t o t h e proper level, p l a c i n g t h e system i r i r e a d i n e s s for o p e r a t i o n . 1n:s

V e n t i l a t i o a of Coclant Cell.. The c e l l homirlg the coolant-salt system is connected t o the b u i l d i n g v e n t i l a t i o n system by a duct i ~ h i c h exhausts 5500 c f m of a i r . T h i s was enough t o maintain a negative p r e s sure in the area u n t i l the r a d i a t o r blmers were p u t i n t o o p e r a t i o n . Then ail- I-eakage froin t h e r a d i a t o r enelos-ure exceeded t h e cell exha~~3-b c;qaci.ty. E v e n a f t e r c o n s i d e r a b l e work on t h e enclosure, tl?e leakage was t o o xriuch.

To allevi-ate t h e siLuation, t h e i n l e t of the souLll d.wiuli& blotre:: w a s connected i o the coolant drain-%ank c e l l by ductwork. This blower can now yet u - n a'oout '7400cfm o f a i r t o tile duct leading -to ilie coolafit, stack, Now when t h e annulus blowes i s used i o siq)pl~rn-eiitt h e r e g u l a r exhawt, t h e main r a d i a t o r bl owem c a n 'LIP operated wiitiiout rari si ng t h e c o o l a n t - c e l l pressure above atmospheric. Shielding -..-___.___

Complete r s d i - a t i o n swv-eys of t h e r e a c t o r a r e a were rnade a% each 'iiighe:L- power l e v e l from 1. t o lo00 k%ru These silowed a few a r e a s of unaccep-tably high r a d i a t i o n . The treated-"water system has ahead-2 been dri.scu.ssed. S c a t t e r i n g of f a s t neutrons and ga-mfia rays from .the reaci;oi: cell. i n t o Lhe coolant d r a i n c e l l through -the 30-in. ce1.1 venti.II.z.tj~oii l i n e caused excessive dose r a t e s o u t s i d e t h e access door. A wa1.1 of 16 i n . of concrete '01-ock and 6 i n . of b o r a t e d pol-yetlnyl-ene was b u i l t i n the coolan-L d r a i n ce1.l~t o reduce dose r a t e s a-t the door t o acceytab1.e values. (Tine door i s locked during nuclear o p e r a t i o n t o prevent e n t r y i n t o t h e ce1.L.) Gamma r a d i a t i o n from t h e f u e l off-gas l i n e i.n a 3-f-i; ga:p between t h e reactor bui.l.ding and t h e vent house required. eart,h s h i e l d ing, a x had been expected. We a l s o expected t h a t a d d i t i o n a l s h i e l d i n g woixlCi be required. direct1.y above t h e reac-Lor, where t h e r e a r e Large cracks However, p r e s e n t i n d i c a t i o n s a r e tl1a-i; tile be-f;ween tine s h i e l d blocks s h i e l d i n g t h e r e wri.11 be adequate. I

Component Perfoimiance Considerable e f f o r t w a s spent i n modifying and a d . j i s t i n g t h e rad i a t o r t o meet o p e r a t i o n a l requirements. Other components performed well, bui; t h e r e were some f a i l u r e s in conv-entioizal. equipment. Radiator

The origj.n.al. r a d i a t o r doors proved i-nadeqiiate i n t h a t t h e y bowed when the r a d i a t o r w a s hea'ied. I n A 1 g i x . t ; 1365, doors of i l n proved design were ins'l;alled. Tests showed t h a t t h e s e doors deformed f a r less when ho-t and s u f f e r e d none of -the permmen.% waqing of t h e f i r s t doors. Heat l o s s e s due t o air leakage a r o ~ m dt h e doors contiiliued t o p r e s e n t a pro'uLern, however. Before all parts of tne r a d i a t o r tubes could be g o t t e n i n t o a n axceptabl-e temperature range for Cilli-ng writh s a l t , it w a s necessary '60 work out s e v e r a l minor changes. 'These i n cluded shi-mmj-ng t h e gaskc-L t o conform t o t h e complex bowing of t h e doors and enclosure and- changing t h e h e a t e r w i r i n g to give a nonuniform heat and- jammed

input over t h e f a c e of t h e r a d i a t o r .

A-i;f i r s t t h e new doors d i d not move f r e e l y . On s e p a r a t e occasions, both doors h u g up and f a i l e d t o lower, l e a d i n g to snarrJ.ing and kinking of t h e l i f t i n g c a b l e s . Rel.ia'ol..e, free movement of .tile doors was a t t a i n e d only a f t e r s e v e r a l r e v i s i o n s . The seal. s t r i p s were moaif i e d -to e1i.minat.e

Wlien -tile rain Iilower’:; were operated ’GO t e s t the doors, o-t;her diff i c u l t i e s !ieeane xpi~arent. A i r leakage -2rom t h e sheet 111et:alenclosure was clearly excessive (about :LO,(100 efin), e w n thocgii t h e 0-rigirial de~‘igjnhad been modiirfied t o include hoods ii.ito which the doors were r a i s e d . The lea,kage was reduced by i n s t a l l i n g as-bestos c l o t h b u ~ b saxouxd. the cabl.es, tzpplying s h e e t netal 4;o co-ine gaps arid packing tnszilation i n others Ev-en so, t h e leakage re‘quired. an i ~ c r e a s ein t h e cel.1. exhaust c a p a c i t y .to prevent p r e s s i u i z a t i o n of the c e l l . I ~ a k t i g eof hc-L a i r in1;o the r e gion Jus+, above the enclosure earwed overheahing of e l e c t r i c a l insula-Lion oil the xumerous thermocouples and pawel’ l e a d s i n ,this vTcfnity. The prof-,le111 was ~ o ~ i i p o ~ l cbecause led t h e new door hoods blccked %he c i r c u l a t i o n of Teak stoppimig and more t h . e m . l . . i n s u l a t i o n air ffr.orn the cell- c o o l e r s improved t h e situ;.,tion, bui; i-I; was s t i l l n e c c s s a ~ t~oj re”locate junction ’ocxxes In. cooler l o e a t i o n s al.oiiy -the cell ws.l.l. m d install higher-tempera%-me e l e c t r i c a l . i n s u l a t i o n on the thermocouple Rad t h e e l e c t r i c a l lesdc over t h e enclosure. F l e x i b l e ducts aiid vanes ~nlereLGed i;o r e d i r e c t C O G 1 a i r f l o w over the lea& a n d . t h e l i f t i n g niec’.hmism. see “Compunerit ~ e vel.oprmi~% ?’ for a d d i t i o n d . infwnmtion a’oout the i n o a j f i c a t i o n s

During %he l-MFr operation in rim 4, s a l t froze 5.n %’ne l i n e s conFT 201, t h e v e n t u r i flowmeter l o c a t e d i n .the i.xpper park of Yne rad-iator e n c l o s u r e . GTi-Mi the b l o ~ e son, cool air kakage past t h e elerrierit rmde it necessary to t u r n 0x1 l o c a l h e a t e r s t o prevent freezing. W l l i e g t h e ‘ b l o w e r was st,oyp?d-, S,ne h e a t e r s had t o ’oe t u r n e d down to avoid 1% q q e a r e d l i k e l y t h a t i n higher-power o p e r a t i o n , w i % h overheating grezt-ter air pressixe in t h e radiator, t h e element could n o t ’oe kept from f r e e z i w . ‘Kierefore, between TW-s4 aiid 5, the top of t h e enclosure was cuz opec., part of t h e stacked-block insul-ation ‘ w a s removed, and f i b r o u s i i l s u J - a t i G f i q pro-tected by shim s t o c k , w a s i n s t a l l e d axauld t h e e1ememt-L. 0p)erat;ion i n Y”LIII 5 indicated that %he i n s u l a t i o n was thexi ad.equa.te. n e c t e d to

36 O t ' h e r Corxponeiits .....--.--

S e a t e.-.... r s . Very l i t b l z t r o u b l e w a s encountered wi-th. t h e h e a t e r s on the salt system. _____I__

A f s u l t y thermocouple l e d t o fail.?ire o f t w o elements i n H 106-1,a h e a l e r on tine finel d r a i n l i n e t o d r a i n tank 2, i n October 1.965. I i w e s t i gation of an anomalous dro2 i n c u r r e n t showed. t h a t t w o elements had f a i l e d a f t e r a. lengthy p e r i o d i n which .the h e a t e r was operati.:o.g near t h e maximum power (about 50$ higkLei- t h a n o t h e r h e a t e r s i n s i m i l a r l o c a t i r m s ) 'The thermocouple vhose reading w a s used t o s e t t h e h.eater w a s t h e n checked. One l e a d w a s grounded i n t h e shi-eld, causiIig the i n d i c a t e d 'cemperatnrr.e t o be 400'F 1 . 0 ~ . All t h r e e elements i n H 1.06-1. were r e p l a c e d . X rays showed t h a t about 1 i n . of r e s i s t a n c e w i r e i n Lhe two fai.lLed. eI.ernents ?*ad melted. I n s p e c t i o n of t h e pipe showed no W a g e from t h e a b n o ~ m a l l yhigh temperature *

Al.1. h e a t e r s performed proper1.y during t h e hestup of .ti= f u e l and coolant loops, w i t h . one minor exception. A broken lead turned up on a h e a t e r between t h e r a d i a t o r and t h e c o o l a n t pump. It was simply :recon.ne c t e rl..

After t h e s t a r t u p , one of t h r e e eleJwnts i n one of

t h e heat-exchanger o t h e r elements were enough hea.tPrs f a i l e d . No a c t i o n w a s takea hecainse t h e t o produce t h e desi-red temperature.

Drain-CellSpace-Cooler Motor. Tjne fans on t h e r e a c t o r - snd d r a i n ..... c e l l space c o o l e r s were o r i g i n a l l y d r i v e n by 3-hp motors; 1.0-hp motors were subsequently instal..l.ed t o provide t h e a d d i t i o n a l power needed. ?-,o keep t h e fans running i n t h e event o f am a c c i d e n t which p r e s s u r i z e d t h e cells.

The motor on t h e dxain-cel.1- c o o l e r f a i l e d a t -the end of run 5, af-Ler aboi.rt. 2900 hT of o p e r a t i o n . 'The cooler was removed, and examination showed -khat the r o t o r had s l i p p e d a l o w t h e shaft imt3.1. t h e r o t o r P m blades rubbed, causing t'ne s t a k o r windings t o overheat and Lo be deskroyed. Norrrlally a .Corce of 2 or 3 t o n s i s required. t o f o r c e the shaft out of a rotor o f t h i s s i z e .

This very uniisual f a i l u r e does not appear t o r e f l e c t a weakness i n design, b u t most l i k e l y jmproper manufacture. Therefore, 'the r u i n e d mo-Lorwas r e p l a c e d w i t h one p m c L i c a l l y ri.dent,tcal..

Component I...- __Cooling _. Rmps The t,wo component cooling p w p s a r e l a r g e , ~ o s ~ - ? - , i v e - d ~ s p l ~blowers ~ e m ~ ~which it suppl-y cool.ing a i r t o f r e e z e valvzs and o t h e r eqi~i.p:mnt 5.n t h e r e a c t o r and drain-Lank cel.1.s Whenever the fuel. system i s h o t , one pump 5.s kept. i n operation, wi-th bhe oLher on sl;anrlby. By the end of February 1966, CCP 1. had. operated 4995 h r ; CCP 2 had. operabed only 1620 hr" I

The d r i v e b e l t s on CCP 2 broke a f t e r 145.4h r of o p e r a t i o n and a g a i n a f t e r 11 a d d i t i o n a l hours. The b e l t s had been operated a t loadings i n excess of t'nerir rating s i n c e t h e beginning of operai;i.on when t h e sheaves were changed 'LO reduce blower speed, A f t e r t h i s was recognized, followi.ng Lhe second f a i l . u r e , t h e sheaves and b e l t s were repl-aced w i - t i l a poly-

37 V-belt d r i v e addequate â&#x201A;Źor -fne 75-lr1p motor c a p a c i t y . The original. b e l t s on CCP l. l a s t e d for 4.360 hr b e f o r e f a i l u r e . They t o o were repkdced with a poly-V-belt d r i v e . A t t h e time of the second f a i l u r e of t h e CCP 2 b e l t s , it was &iscovered t h a t the discharge check valve 0x1 this blower was i n o p e r a t i v e Tliis valve is a 6 - i n . b u t t e r f l y - t y p e valve s~i"i;ha n e l a s t o n e r hinge holdi n g two flappers i n p l a c e . The hinge had broken, a3.lowing one flxpper t o fa.11- off. TEX resul-t xas tfiat CCP 2 %iotored" 'because of r e v e r s e r'Low when (XI? 1. was operated. The check val-ve w a s rebuilt and r e i n si;all.ed *

Diesel. Generators Three Diesel-powered g e n e r a t o r s , each wi-tii a c a p a c i t y of 300 'm, supply emergency ac ptswer t o motors and h e a t e r s i n the MSEZ. There has been no occasion 02 w-hi& t h i s emergency power was needed. The d i e s e l s are sturbed ~ n c ea week, am3 once a month Lhey are o p e r a t e d under p a r t i a l l o a d . They have aLso been operated d u r i w plamied pcwer ou-tages f o r up t o 6 hr.

I n November 1945, cool.ant l e a k e d in.t;o the crankcase of I)G 3 , and it was foixid t h a t an imperfect head made a. bight seal. 'be.bweeri head and 'dock i q o s s i b l . e . T'ne head was r e p l a c e d a d t h e b o l t s torqued t o t h e manufacturer's s p e c i f i c a t i o n s . I n February a c r a c k w a s found i.n t n e bl.ock a t one of "ne b o l t h o l e s . A s t o p l e a k cornpawid- 'was used teinporariljr w i t i l - r e p a i r s e o i l d be plamied. kt t h e maniifacturer 's recanmendabion, r e p i r of the crack was a t t e m p b e d by meta1.l-i~a x e welding. The attempt was only- p a r t l y s u c c e s s f u l , and.s t o p - l e a k compoixid w a s needed t o h a l t s l i g h t seepage from a c r a c k a d j a c e n t to Yne weld. E'urther a t b e r n p t s at r e p a i r a r e deemed i n a d v i s a b l e , and t h e expense of a new block does no% appear j u s t i f i a b l e i.n vlew of t h e purpose or" DG 3 - if i-t; were -bo P a i l when. c a l l e d on f o r emergency power, it w 0 u . d at worst cause d e l z y Presently DG 3 i s t e s t e d rourtine!-y arid incoriveiiience b u t no s y s t e r n hxflage w i t h t h e o t h e r diesels, 'out the crankcase oil i s monitored es;pecialLyc a r e f u l l y f o r t r a c e s of c o o l a n t . A i r Compressors. Compressed a i r a t t h e NSXE i s s u p p l i e d b y t h r e e r e c i p r o c a t i n g a i r compressors. ' W o of the compressors, AC 1. an& AC 2, provide iiistmunent; a i r . 'Yhe o t h e r , AC 3 , s u p p l i e s air %or s e r v i c e needs and, i n emergencies, can supply a i r t o the instrument sys%em.

':["ne se.rvLce air compressor i s an 8-in.-bore, 7 - i n . - s t r o k e 2 Sl4-rprn rmchine w i t h 'Teflon r i n g s , i n s f ; a l l e d . new i n 1.962. la more than three y - e a r s of s e r v i c e , I t fa5led once, in 1964, xhen blockage of the a f t e r cooler discharge l i n e by a f a i l e d check valve led .bo excessive :pressure a n d a head gasket f a i l u r e .

'The instrument a i r compressors are a l s o &in. -bore, '7-111. -stroke machines, b u t they were o r i g i n a l l y equi.:ppd w i t h carbon r i n g s arid ope r a t e d a t 600 rpm. Eo-th had been used elsewhere, and i3oth had been overhauled aid equipped w i t h Teflon r i n g s b e f o r e being y l a c e d lixi s e r v i c e ;:-ct; .the PEN3 i n 1964,. 'L'hrougli Jxnuary 1946, sLx head gasket f a i l u r e s had occurred j.n t h e s e two compressors, t h r e e on each compressor e

Inyiestigation of the excessive faiLure r a t e on A-C 1 a i d AC 2 Led t o t h e concl.insion. th2-L the f a i l u r e s 'were caused by overheating of the

38 c y l i n d e r l i n e r , which occiirred whenever the cooling-water temperatiire o r %he load. was s l i g h t l y above noma?_ (but s t i l l w i t h i n tile s p e c i f i e d r a n g e ) . T h i s w a s a t t r i b i i t e d t o bind7.n.g of t h e Tefl..on p i s t o n r i n g s , which w a s observed a t ’iinies a f t e r b r i e f operaLion a t rated load. When t h e r i n g s begari t,o bind, t h e c y l i n d e r l i i i e r a p p a r e n t l y overheated, expanding a ~ i a ~ 3 . l . y and deforming -the head. gasket. Water then leaked. frrom. tne cool-ing passages i n t o tl-le c y l i n d e r when the co~mpressorcooled and Uie c y l i n d e r I.i.j?er shrank. ‘The compressor manufacturer iIOW recoi;rnend.s a maximum speed of 514 r p on ~ 7 - i n . - s t r o k e cornpi-essors; a p p a r e n t l y p i s t o n speeds at, 600 rpm were t o o hligl-~a f t e r Teflon rings were substlitirted for carbon. 1-L was possi.bl.e t o reduce t’ne speed on AC 1 and Ai: 2 -Lo 512 r p m and s t i l l meet t h e reqi’uireixents for instmment a i r flow. This change w a s made, t h e r e f o r e ; by cha:ogj.ng t h e d r i v e sheaves and. bel..ts and- a p p a r e n t l y the binding and overheating were eJ.i:r~Lnat,ed.

I n s p e c t i o n of t h e Fiiel. Pump

The f u e l pump r o t a x y element was removed f o r i n s p e c t i o n a f t e r t h e f l u s h s a l t c i r c u l a t i o n a’i the end. o f :run 3. The pump was checked f o r d2imernsional changes d e p o s i t s corrosiori o r e r o s i o n of‘ hyd.i-au.lic p a r t s , and for rubbing of c l o s e - c l e x r a a c e running f t L s

The puiip w a s g e n e r a l l y i n sood cond.ri.t,ion, and nothing w a s f‘uund that %roul.d. i n t e r f e r e w i t h th.e s a t l s f a c t o r y opera-Lion oi” t h e piini~. Tinere was no i n d i c a t i o n of rubbing of t h e rimming f i t s or o f c o r r o s i o n o r erosioj? of t h e hydraulic p a ~ t s The only dimensional. change w a s a 0.006-in. growth of t h e pump .Lank bore d.iameter where -the upper O-ring mates with t h e P L U I I ~ ta:ok.

F i g i . x e 1.18 i s a photograph of t h e lower pari; of the roi;ary element in t h s deconts‘minxtlon cel.1 where it w a s exami.ned. The dark s t a i n s on t h e s h i e l d plug a r e t h e r e s u l t s of an o i l l e a k t h r o i g h t h e gasketed j o i n t a-t -the m t c h b a s i n f o r ’die lower oil. seal... This oil had ru11 d m m tile s u r f a c e o f t h e s h i e l d pl-ug, where il; h.ad. become coked by t n e higher tempera,tv.res near t h e bottor;. Some of t h e o i l had rer,ched_ t h e upper O-ring groove a t the bottom of the shiel.d pJ.iig and had becomc coked- ri.n -t;he groove) but none appeared. t o have leaked p a s t -Lhe O-ring d x r i n g high-tempera’bure operation.. Some f r e s h o i l w a s observed below -ther i n g after t h e r o t a r y e1.emen.L had Seei! moved t o t h e decor!.i;8mi.natioi? ceLL, b u t we b e l i e v e this o i l dripped f r o m the open o5.l Lines during Liie i i r a n s f e r t o t h e c e l l .

The pho,Lograp’n a l s o shows p a r t o f a deposit o f f l u s h s a l t ’chat f a i l e d t o & a i n from t h e l.a’nyrintli f l a n g e just above t h e irrSpel.ler. Calcu.1.ations OP fission product activity a f t e r high-power opera’iion i n d i c a t e d t h a t this incomplkte b a i n a g e would n o t Lncrease t h e maintanance hazard. s t g n j - f i c a n t l y , provided f l u s h salt i s c i r c u l a t e d . t o fJ-iish f u e l from t h i s l o c a t i o n p r i o r t o t h e removal.. There were a l s o deposits o f s a l t t h a t contaiaed fiie3. i n both t’r!.e upper and ].over O-ring g.-ooves These deposits would. n o t be e f f e c t i v e l y diluted. dinx-ing f l u s h s a l t operaLion and wou.?..d consti’iu-Le t h e major r a d i a t i o n source dupi:iLg maintenance operations.

F i g . 1.18.

MSRE F u e l - C i r c u l a t i n g - P a p Rotary Element After Run 3 .

The p a r t s of t h e r o t a r y element t h a t had been i n c o n t a c t w i t h t h e s a l t had clean, b a r e metal s u r f a c e s , while t h e p a r t s e x p o s e d t o t h e t r a n s i t i o n , which may be had a t h i n black f i l m . There w a s seen i n F i g . 1.18, between t h e two of s u r f a c e , b u t t h i s t r a n s i t i o n a l t d e p o s i t above t h e labyw a s s l i g h t l y above t h e a c t u a l l e v e r i n t h f l a n g e and a smaller s a l t d e p o s i t i n t h e pmrp v o l u t e were a l s o p a r t i a l l y covered with a t h i n b l a c k f i l m . * The pwrrp w a s r e i n s t a l l e d using remote maintenance techniques s o t h a t t h e s e techniques and procedures could be evaluated. Four u n i v e r s a l j o i n t s on t h e f l a n g e b o l t s had been found b r o during t h e disassembly were r e p a i r e d p r i o r t o t h e r e i n s t a l l a t i o n of t h e r o t a r y element. The f a i l u r e s r e s u l t e d from excessive b o l t i n g torque t h a t had been used e a r l i e r t o o b t a i n a n i n i t i a l s e a l on t h e f l a n g e . Heat Treatment of Reactor Vessel A f t e r t h e r e a c t o r v e s s e l w a s i n s t a l l e d , tests of Hastelloy N from t h e h e a t s used i n t h e v e s s e l s h o w e d t h a t t h e c l o s u r e weld between t h e top head and t h e f l o w d i s t r i b u t o r r i n g would be expected t o have poor mec h a n i c a l p r o p e r t i e s i n t h e as-welded condition. F u r t h e r t e s t s showed t h a t t h e r u p t u r e l i f e and d u c t i l i t y , which were unacc ly low, could

40 be p r a c t i c a l l y r e s t o r e d t o t h o s e of t h e base metal by s t r e s s r e l i e v i n g f o r 50 t o 100 h r a t 1400°F.9 Although t h i s is w e l l above t h e normal ope r a t i n g temperature of t h e MSRE, it w a s a t t a i n a b l e with t h e i n s t a l l e d h e a t e r s , and c a l c u l a t i o n s showed no harmful thermal s t r e s s e s would be involved. Therefore t h e v e s s e l c l o s u r e weld was h e a t t r e a t e d i n p l a c e . Temperatures were monitored by s i x thermocouples evenly spaced around t h e v e s s e l j u s t below t h e weld. Because of gaps i n t h e shroud of v e r t i c a l h e a t e r tubes around t h e v e s s e l , a p e r f e c t l y uniform temperature could not be a t t a i n e d . A day w a s spent a t about 1300°F, a d j u s t i n g h e a t e r s t o minimize t h e temperature spread. Then f o r 90 h r t h e lowest tempera20°F, while t h e h o t t e s t thermocouple w a s at t u r e w a s h e l d a t 1400 1460 20'F. A f t e r t h e v e s s e l w a s cooled a t t h e end of t h e treatment, i n s p e c t i o n showed t h a t t h e furnace and i n s u l a t i o n were undamaged.

Stress Analysis of Reactor Piping and Nozzles

The MSFB f u e l system w a s designed f o r t h e f u e l pwnp and t h e h e a t exchanger t o move h o r i z o n t a l l y and v e r t i c a l l y . This was done t o keep t h e s t r e s s e s low i n t h e p i p i n g and equipment nozzles while accommodating t h e expansion and c o n t r a c t i o n of t h e c l o s e l y coupled system as it i s During t h e prenuclear and c r i t i c a l t e s t cycled between 150 and 1300'F. i n g we found t h a t t h e pump mount could not be depended on t o move v e r t i c a l l y . A t t h e same time we l e a r n e d t h a t t h e creep p r o p e r t i e s of t h e metal i n t h e r e a c t o r v e s s e l and t h e p i p i n g i n s i d e t h e thermal s h i e l d would d e t e r i o r a t e with neutron i r r a d i a t i o n . The former condition could cause t h e s t r e s s e s i n t h e p i p i n g and nozzles a t t h e r e a c t o r v e s s e l t o be high with t h e system hot or c o l d . The l a t t e r r e q u i r e s t h a t t h e s t r e s s e s be kept low when t h e r e a c t o r i s a t high temperature, although normal des i g n s t r e s s e s a r e p e r m i s s i b l e below about 800°F. According t o our c a l c u l a t i o n s , acceptable s t r e s s e s a t t h e r e a c t o r v e s s e l nozzles could be obtained by r a i s i n g t h e pump 1/2 i n . and t h e h e a t exchanger 1/4 i n . from t h e i r e x i s t i n g c o l d p o s i t i o n s and f i x i n g them a g a i n s t f u r t h e r v e r t i c a l movement. This "cold s p r i n g i n g " would r e s u l t i n t h e s t r e s s e s being high a t low temperature, and expansion of t h e piping on h e a t i n g would lower t h e s t r e s s as t h e temperature i s r a i s e d . Because of t h e r e l a t i v e l o c a t i o n s of t h e supports, f i x i n g t h e pwnp and both ends of t h e h e a t exchanger w a s found by c a l c u l a t i o n t o r e s u l t i n excessive s t r e s s e s i n t h e heat-exchanger nozzle during t h e thermal cyc l i n g . However, acceptable s t r e s s e s could be obtained t h e r e by mounting t h e h e a t exchanger on s p r i n g supports a t t h e end c l o s e s t t o t h e pump. The changes were made a s i n d i c a t e d above, and t h e f u e l system was heated t o 1200°F. There w a s no a p p r e c i a b l e v e r t i c a l movement of t h e h e a t exchanger on t h e s p r i n g supports where a downward movement of 0 . 1 i n . had been expected. This i n d i c a t e d t h a t some of t h e assumptions used i n t h e c a l c u l a t i o n s were not a c c u r a t e and t h e c a l c u l a t e d f o r c e s a t t h e h e a t exchanger were t o o high, or t h a t t h e j u n c t i o n of t h e nozzle t o t h e s h e l l of t h e h e a t exchanger y i e l d e d under small f o r c e s . A f t e r t h e system was cooled, s t r a i n gages were i n s t a l l e d on t h e h e a t exchanger nozzle and on t h e p i p i n g t o t h e pump. The h e a t exchanger was

r a i s e d anti lowered a-ooint 118 i n . w h i l e tile forces on the 3pri.W s u - p o r t s and t h e s t r a i n s were mea,smed. The measixenests inc:Xczted. that; .the rfiaximum s t r e s s was fn t h e heat-exchanger nozzle, b u t that high s t r e s s e s in t h e nozzle were accompanied by l a r g e f ~ r c e son t'ne s p r i n g s . We concluded t h a t t h e s p r i n s mounting should a c t to r e l i e v e any Large vertical f o r c e s on. t h e nozzle a d t h a t t h e r e v i s e d i n s t a U a t i o n was s a t i s f a c t o r y .

Inst m e n t at ion and C ontro l s General F O ~ ~ I L Zdesign L of t h e IJISRli: i n s t r a n e n t a t i o n and c o n k r o l s system is ~m+f complete. The need for furYher addLtions and. :mociifiea,tions t o t h e instrument and c o n t r o l s system hns becorr~apparent as ini'clal. operatTom progress Some provide a d d i t i o n a l s y s t e a p r o t e c t i o n , b u t i n khe m a j o r i t y of c a s e s t h e purpose i s t o improve performmee a n d provide niore infomixit i o n f o r t h e o p e r a t o r . A few minor d e s i g n e r r o r s were c o r r e c t e d , and Exsane i n s t r u m e n t a t i o n was added t o siurplify mi.ntenimce procedines c e p t f o r some s p e c i f i c a t i o n s h e e t r e v i s i o n s and p r e p a r a t i o n of a desigrL r e p o r t , documentation is complete. e

S a f e t y InstrwnenCation

No nlajor changes t o t h e flux and ternperat.ux-e s a f e t y systtirn were r e q u i r e d . Minor m o d i f i c a t i o n s were -made as follows : 1. The Inodd Q-2623 r e l a y s a f e t y element w a s a l t e r e d by r e p l a c i n g t h e 115-v ac r e l a y s w i t h 32-v dc r e l a y s . T'nis e l i m i o a t e d ac, pickup on t h e o'c'ner modules through wlriich r e l a y c o i l c u r r e n t i s routed and reduced tine l i k e l i h o o d of s p u r i o u s t r i p s , p a r t i c u l a r l y when t h e 4-2603,f l u x ampl:i-fier t r i p p o i n t s a r e reduced by a f a c t o r of 1000 from 1-5 Mw t o 15 Irw of r e a c t o r power. 10 2. The v o l t a g e a d j u s t i n g r e s i s t o r i n t h e rod drive c l u t c h c i r c u i t vas i n c r e a s e d from 500 t o 750 o'mr~.s t o f a c i l i t a t e s e t t i n g t h e c l u t c h curr e n t t o t h e necessary and s u f f i c i e n t m i r i i m u i value *

3 . Current meters were placed i n t h e rod d r i v e motor c i r c u i t s . Gross changes i n motor I-oa.d, caused, f o r example, by a s t i c k i n g rod, may be i n f e r r e d an i n c r e a s e i n meter reading.

4. Dyrmnic braking c i r c u i t r y f o r rod d r i v e L (servo-contuoZled ro&) has 'oeen designed, b u i l t , and t e s t e d , w i t h i n s t a l l a t i o n scheduled f o r March 1966. Braking a c t i m i i s o b t a i n e d by disch.arging d i r e c t currerit from a c a p a c i t o r through t h e motor f i e l d wiridLng:s when th.e dxive

motor i s t u r n e d o f f . This break w i l l provide a s u b s t a n t i a l re&uction i n c o a s t k g of t h e rod &ive a f t e r t h e pmer i s twitched o f f . A s a r e sult; it will t a k e less back-and-forth Jogging to get small increments of r o d motion when nianually shirrirning. Servo p e r f o m a n c e i s expected t o i m prove f o r t h e sane reason.

...... .

T o a s s u r e a d r a i n , a d d i t i o n s and r e v i s i o n s t,o e x i s t i n g s a f e t y c i r c u i t s were designed t o open t'he f u e l d r a i n - t a a k v e r t v a l w s on s i g n a l from high neutron f l u x (scram> and keep them open m"cj7. manual r e s e t i s used- t o pemiit r e c l o s j ng.

Wj-de-Han.ge Counting Channels

Heac'cor power and period information r"173i-n t h e s e two f i s s i o r i c o u n t e r channels1'. provides i n t e r l o c k s which govern permi.ssible r e a c t o r power 1eveI.s ( c o n t r o l system modes)12 and .reaci;or. fill, which i.:obibii; rod w i thdra7val during start, and which provide c o n t r o l - r o d r e v e r s e ac'iion.

Very general.]-y and typicaS.S.y, r e a c t o r p e r i o d s i g n a l s from counting cha-mels o p e r a t i n g a t low i n p u t l e v e l s are c h a r a c t e r i z e d by slow response. This i n h e r e n t delay prod.uced a problem w i t h s e r v o - c o n t r o l l e d r o d w i t h d r a w a l during s t a r t . I n a servo-cont;rolled s t a r t , -Uie dem:o.d. s i g n a l causes t'ne r e g u l a t i n ~rod t o withdraw wi-til. t h e p e r i o d - c o n t r o l l e d "wi.t;iid r a w i n h i b i t " i n t e r l o c k o p e r a t e s . If t h e p e r i o d continues t o decrease, t h e "reverse" i n t e r l o c k a c t s t o i n s e r i ; t h e r o d s in d i r e c t opposi-tion t o the servo demand-. These "withdraw i n h i b i t " and "reverse t r i p p o i n t s were origiiial.ly e s t a b l i s h e d a t p e r i o d s of t 20 and 4.10see respectPb--ly. The delayed low-level response of tb.e "inhibi-LI' i n t e r l o c k allowed suff i c i e n t incremental r o d withdramil 'to produce a lO-sec period. and ti7u.s c a m e a r e v e r s e . The s i t u a t i o n was aggravated by coas-birg of t h e shiml o c a t i n g motor i n t h e regula-Ling rod l i m i t switch assembly . 1 3

A s remedial measu-res, t h e 'hithdi-aw i n h i b i t " and ''reverse I f p e r i o d t r i p p o i n t s were changed- t o 4-5and +25 see, respec-Li-vely, and. an e l e c t r o mechanical c l u t ch--brake w a s i n s e r t e d i n t'ne shim- loca-Ling mo L o r - & r i v e t r a i n . The dynamic brake d e s c r i b e d above i s a l s o expected t o reduce t h i s p e r i o d overshoot problem. P r o v i s i o n f o r t e s t i n g t h e period and log power i n t e r l o c k t r i p s i n t h e wide-range counting channels w a s p r o v i a e a . T e s t i n g i s d.onc r o u t i n e l y by I a s t r w n e n t a t i o n and Controls D i v i s i o n maintenance personnel and i s accomplished by push b u t t o n s 3-ilside $he instrument c h a s s i s . Nuclear _--

Ins L m e n t P e n e t r a t i o n

We asswned t h a t t h e neutron f 3 . i ~i ~n t h e instri~meni;p e n e t r a t i o n s wou1.d 'LO d-ecrease exponential-1-y w i t h i n c r e a s i n g d i s t a n c e from t h e core vessel.14 T'nis implies t h a t most of t h e f l u x w i t h i n Llie p e n e t r a t i o n o r i g i n a t e s w i t h neutrons e n t e r i n g -the lower end f a c e of the p e i i e ~ t r a t i o n . Figure 1.19 shows that coucre-Le shieldi-ng was added i n . a n effort t o s h i e l d tiie pen=.t r a t i o n from o t h e r sources of neutron f l u x . The v e r a i s t x t ri.n t h e widewi..l-1. compeiisate range countihg channel 's model 61-2616 f u n c t i o n f o r any reasonable d e p a r t u r e from an exact e x p o n e n t i a l a t t e n i n t i o n of fl-im; however, it became a p p r e n t di1ring t h e f i r s t s e r i e s of crik.ca.1 cxperhen-Ls t'na'i f l m aLtenuation w i t h i n t h e instr-mcnt p e n e t r a t i o n w a s devtnting, grossly, f r o m t h e assimed e x p o n e n t i a l curve. T h i s unseemly behavior i s il_LusI;ra.ted by curve A on F i g - l.20, wh,ri.ch shows f i s s i o n counber response (normalized count r a t e ) vs withdrawal from t h e lower end of t h e

teiid

4.3 penetrati.on i n guide tube 6 . It was reasoniable t o conc3.u.d.e from -%his, axid from siiifilar curves, t h a t the excess neutrons r e s p o n s i b l e for t h e &ist o r t e d p a r t of t h e c i m e were e n t e r i n g t h e p e n e t r a t i o n along i - L s length. The count rates i n o t h e r guide tukes nearer t h e upper half o f t h e guide tube were even rnore d - i s t o r t e d t h a n curve A.

:r"l-wr f i e l d with a t t e n i m t i o n p e r curve A precludes successful. op-

eration of t h e wide-range counting instrumentation. We decided t o s h i e l d t h e f i s s i o n counters from stray, s i d e - e n t r y neutrons w i t h s h i e l d s of s h e e t cab6wn which were i n s e r t e d i n t o guide tubes G an& 9. A s a, counter t r a v e l s u~ a guide %ube d.wing wit'ndraMa1, it f i r s t e n t e r s a p a r t i a l l y s h i e l d e d s e c t i o n of the guide t u b e . rPne p a r t i a l s h i e l d i n g is obtaFned by using wedge-shaped. s t r i p s of ca&n.iurn l a i d around the guide tube, which provide

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SFCTlON A-A LOCATION O F GUIDE TUBES

CUTER S H E L L REMOVED FOR C L A R I T Y - S H 4 D E D WEDGES A R E C A D ' v l l ? M - U N S H A 3 E D WEDGES ARE ALUMINUM

F i g . 1.20.

Guide Tube S h i e l d i n t h e MSlW I n s t r u l n e n ~P e n e t r a t i o n .

e v e r - i n c r e a s i n g s h i e l d i n g from s i d e - e n t r y neutrons as t h e coun-Ler i s wikhdrawn. The bases o f t h e s e long narrow wedges occiq)y t h e f u l l periphery of t h e s h i e l d tube st i t s upper end and. thereby provide a mwth transi-tion t o t h e 100% wraparound cadmim sl,eve which f o l . h w s . This s h i e l d ing, F i g r n1.20, was an emineii~tly su.ccessfu1 answer to 'ihe problem; ciirve 33, normalized couirt r a t e vs d i s t a n c e , w a s dbtained a f t e r t h i s s h i e l d w a s i n s t a l - l e d Ti1 guide tube 6.

Because o f very unfavorable geometry t h e s-trongest, p r a c t i c a b l e neu-

tron s o u r c e would- not produce 2 countslsec Prom t h e f i s s i o n counters i n %lie wide-range counting channels u n t i l the c o r e vessel. w a s approximately h a l f full. o f f u e l s a l t ; neither would it produce 2 coimts/sec w i t h f l u s h

s a l t i n tile core a t any l e v e l . This i s t h e minimum count r a t e r e q u i r e d t o o b t a i n the p e r x i s s i v e "confidence 'I i n t e r l o c k which allows f i l l i n g t h e c o r e vessel and xitlidrawing t h e rods. Therefore a coimting channel using a s e n s i t i v e RF3 counter was added t o e s t a b l i s h "confidence" wheii the COFC vessel i s l e s s than h a l f f i l l e d w i t h f u e l saJ..t. With Lhe revised. system, a fuel.-salL f i l l m y begin when t h c r e a c t o r vessel.. i s empty i f Bb'3 cowxt

ORNL-DWG 65-2446

ELECTRONIC RESEARCH ASSOCIATES Z.S/lOUi

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DECADE - SCALER 10-1743-Ci

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F i g . 1.21.

. . . . .

C O W DENCE'CIRCUIT

Block Oiagram of BF3 Counting C b r 7 u e l .

rate r'confidence" i s e s t a b l i s h e d b u t cannot be continued a f t e r t h e rea c t o r vessel i s half full unless "confidence" i s e s t a b l i s h e d w i t h e i t h e r of t h e two wide-range counting chmm-els. When f i l l i n g t h e r e a c t o r vessel w i t h f 1 w h s a l t , rods m%y be withdrawn and t h e fill allowed t o proceed a t my le-rrel i f B5'3 count rate r'confidence" i s established and if t h e d r a i n tank s e l e c i o r switch i s i n %he f u e l f l u s h -tank (E'FT) p o s i t i o n . S e i e c t i o n of t h e ElFT 2 o s i t i o n bypasses the h a l f - f u l l weight i n t e r l o c k and requLres a d m i n i s t r a t i v e xpproval. Fi.gure 1 . 2 1 is a b l o c k d.iagram of Lhia 13F3 counti n g elmnnel.. Personnel Moni.toring system The r e a x t o r buil-ding ra.di.atiion and conttuninzxtim wamiing system

was r e v i s e d t o c o r r e c t soxe d e f i c i e n c i e s and to in-prove i-ts e f f e c t i v e ness as i n d i c a t e d by t e s t s and experience dmFng r e a c t o r power o p e r a t i o n . An al.arm r e l a y w a s i n s t a l l e d i n t h e perso:nnel. and s-back rnonitor alarm systein c i r c u i t i y t o provide an arxunciatiori upon l o s s of: t n e 24-v dc power supply'. Monitron RS-7012, l o c a t e d i n t h e south eud of t n e high bay, vas moved e a s t abouk 20 f t Lo monitor for p o s s i b l e rtidixtion escaping from t h e n u c l e a r i n s t r m i e n t p e n e t r a t i o n . CAP1 kF-7001.was moved- c l o s e r t o t h e s ; m p l e r - e n r i c h e r to monitor i t s o p x a t i o n . Seveml of t h e Q-2091 b e t a - g w - a nionitors were r e l o c a t e d t o provide more pro-tecliiors. One u n i t w a s i n s t a l l e d i n t h e instrixiient shop, one tuxit was removed from tlie health physics o f f i c e aizd i n s t a l l e d i n t h e hall. between Buildings 7503 and 7569, and the tmit i n -the ver?--L house was r e l o c a t e d t o reduce it;; backgrowid response f r o n liries i n -tine vent house. Two aclditional- air horns were added t o increase t h e area covered by t h e horn evacuation sig:nal. One horn was i n s t a l l e d on the s o u t h e a s t c o m e r of B u i l d i n g 7503 ;and- the o t h e r i.n t h e d i e s e l house. Four addLkiorial beacon aLanx. l . i g h t s .were i n s t a l l e d i n a r e a s where t'ne horn rmigh.l; not be heard. A l.igh-L Trlas i n s t a l l e d in Lhe vent house eocdLng-water eq.urip111.entroom1 the switch house, and the P l a n t ~

and Lyuipnent shop building.. A 62-2277 r a t e meter and Q-2101 a l p h a probe w i l l be i n s t a l l e d iri t'ne hot change house. C ont rol Instrmie n t a t i on

Containment. To maintain -Lhe int;eg;rci.ty o f t h e r e a c t o r secondary containiient s o k n o i d block valves w i t h saf ety-grade wiriiig were ri.11stal.l.ed i n t h e fuel-dxaln-tank stem1 dome d r a i n piping These valves a r e i n t e r l o c k e d to c l o s e when. r e a c t o r c e l l a i r activi.t;y o r p r e s s u r e i s above l i m ' . t s - Ifhe i n t e r l o c k s override a m a n u a l switch used f o r norrrwl. operation. of t h e s t e m d.orne d r a i n system. A.c.bimJG7.n.g signal-s were ob'. . Ldined f ~ o mex.i.sting circuits.

J..

Safety-grade c o n t r o l c i r c u i t s werc ins-Lalled. to operate four welds e a l e d solenold. valves serving t h e Cue1. off-gas sample sy-stern. The valves a r e specially designed and coiisCructed f o r use om MSiW containnent systems and a r e i d e n t i c a l t o those previously purchased f o r i x e i n Lhe fuel-pujrp-bawl bubbler l e v e l system. The procurement of f o u r ad-dit i o a a l valves from a comrriercial. source i s nearing coiriple-Lion,

The f u e l sampler-enricher safety-grade conF u e l Sampler-Enricher -.-__ ...... t r o l circuits were revised. t o i n c r e a s e the r d i a b i l i t y of t h e two containment 'uarriex-s b e h e e n t h e prlima~ysystem ( f u e l pump bowl) and the o p e r a t o r . 0riginall.y; t h e c i r c u i t s were designed s o t h a t t h e sample access port could be opener?. ri.S e i t h e r t h e o p e r a t i o n a l valve o r t h e rnain"ienxj?ce val-ve w a s closed. With t h r i s am-ailgement a c o n d i t i o n existed. wherein a siiig1.e f a t l u r e c o u l d permit t h e access p o r t t o be opened when born t h e opera-Lional val-oe and. the niaintenancc valve were open. if t h i s had occurred when t'nc manipulator cover w a s removed, ilie manipir.l.,a.tor boot could have become t h e on1.y containmen'i b a r r i e r between t h e operator a.nd. a e fiue1. pump bowl. S i n c e $'ne hoot could he r u p t u r e d by system pressures i n excess o f 1 0 p s i g , t h i s c o n d i t i o n 7 s considered. t o be bazard.oiis. The c i r c i u i t s a r e now designed s o t h a t both ..,-.~.-" t h c maintenance valve and t h e o p e r a t i o n a l valve must be closed before the access p o r t i s opened. Al..so, t h e removal va>J.ve and. access port must be c l o s e d and- t h e nlain7i_nulaator covei-must be rir~pl-ace b e f o r e e i t h e r the o p e r a t i o n a l o r t h e maintenance valve can be opened. The p o s i t i o n o f the cover i s d e t e c t e d by a newly i n s t a l l e d vacuum p r e s s u r e switch. Additional p r o i -Lion for the i l a t o r b o o t has a l s o been provided by a new ci.rcu.Lt t h a t prevents development o f excessive d r f f e r e n t i a l p r e s s i r e a c r o s s tiie boot, dixing sampl-er evacuation o p e r a t i o n . This protecti.on i s accompl.ished by cloa3.r?.g a valve i n an exhaust li.ne t o t h e vacuum puiq when the difPere:ort,ial prcssure a c r o s s t h e boot exceeds 30 i n . (water column). ~

__c

P'uel. a n d . Cool.ant Pumps. To s a t i s f y e s t a b l i s h e d operating cri-Ler.2aj t h c f u e l and coolank s a l t c i r c u l a l i n g puq) contro.l. c i r c u i t s were r e v i s e d as foJ.I_ows: 1.

In both t h e f u e l and coolant s a l t clirei~l-atingpimp c i r c u i t s , t h e

e x i s t,j.:ci.g pimp bowl level swi-Lch actu.atri.onvalve was changed t o r c duce t h e level at which t h e pump i s stopped-, 2nd one iiew switch was i n s t a l l e d t o prevent pump startiup i m t i J - nor~nalf i l l l e v e l i s reached. Since the sal-t ].eve1 drops 8 to I..@ a f t e r pump startup, tiie s i n g l e

Level switch system previoiisly used did n o t leave enough operating margin t o prevent normal l e v e l f l u c t u a t i o n s from stopping t h e pump and s h u t t i n g down t h e r e a c t o r . 2.

To prevent unnecessary shutdowns, t h e c o n t r o l which i n d i c a t e s t h a t The only purpose of t h i s i n t e r l o c k i s t o prevent pump s t a r t u p u n t i l t h e f r e e z e valve i s c l o s e d .

FV 103 i s f r o z e n i s now s e a l e d out a f t e r t h e f u e l pump starts.

lTixmpers were added around t h e coolant s a l t system heliwn off-gas r a d i a t l o n c o n t a c t s i n t h e f u e l pum$ c i r c u i t t o prevent t h e pump from stopping each time a' c i r c u i t t e s t i s conducted. Tile r a d i a t i o n monitor i s a safety-grade device, and i t s primary fimction i s t o h i t i a t e an emergency d r a i n . BoYn channels n u s t be t e s t e d r o u t i n e l y .

Fuel.. Processing System. A mass f l o w - r a t e meter was i n s t c a l l e d to i n d i c a t e t h e flow of HF t o t h e f u e l s t o r a g e tank during f u e l processing o p e r a t i o n s . The purpose of t h i s second f l o v measurenent i s t o provide a n independent check on t h e e x i s t i n g o r i f i c e meter b e c a m e t h e KF flaw r a t e i s important j.n c a l c u l a t i n g the <xnomt of oxide removed- from t h e f u e l salt. To prevent p o s s i b l e d i f f u s i o n of 112 i n t o t h e J3F gas swpply c y l i n d e r , i n t e r l o c k s were i n s t a l l e d t o c l o s e both t h e 112 and- liE' gas supply s t a t i o n valves when t'ne main gas supply valve t o t h e f u e l s t o r a g e .tar& i s c l o s e d . Operating Experience

- Process and

Nuclear I n s t m e n t s

Control System - Relays. L i t t l e o r no t r o u b l e has been experienced. V i r t u a l l y a l l design changes t o t h e r e l a y c o n t r o l gear have been made t o meet new requirements developed by o p e r a t i n g experience, not to c o r r e c t ml-functj.ons of t'nis qui-pment

Valves.

'The d i f f i c u l t y experienced wi.th t h e pressure c o u t r o l valve,

I'CV 5 2 Z , i n t h e pump bowl off-gas system i s a p a r t of %he l a r g e r g e n e r a l

problem of off-gas contamination1' by carryover of s o l i d s and vapors wiiich a r e deposited i n t h e o f f - g a s l i n e s . Valve-selection c r i t e r i a f o r t h e o f f gas system d i d not include considering nongaseous f o r e i g n matter in t h e off-gas stream.

[Two pressure c o n t r o l valves, PCV 5005 and X V 5 l O A L , i r i %he main i n l e t helium l i n e gave &ifPicul.ty from galli.ng. These valves are being r e worked.

Fressure Transducers. One s t r a i n gage u n i t i n t h e s m p l e r - e n r i c h e r suddenly s h i f t e d c a l i b r a t i o n , b u t during o p e r a t i o n r e t u r n e d t o i t s o r i g i i i a l The most l i k e l y explanation i s m o i s t w e which, after g e t t i n 3 ini;o state t h e device, was baked o u t during s e r v i c e .

Thermocouples Thermocoupl-e p e r f ormanee has been e x c e l l e n t . O n l y one i n - c e l l themiocouple was l o s t durj.ng t h e six-nontln p e r i o d covered by kkis r e p o r t . Tine p l a s t i c i n s u h t i o n on t h e r a d i a t o r tner111oi:o1q?1.~j lead wires s d f e r e d from l o c a l temperxtures' 7 whicli were substantial1.y i n exc e s s of those a n t i c i p a t e d . Xermedial m e a s z i n s such as insula-Lingi n d i -vidud.. wl.res with cerLunic beads d i r e c t e d flows of cool-ing a i r , a ~ i di n e

s u l a t i n g t h e high-texrpera,tinre regions from h e a t sources have reduced., b u t n o t eliminated, t h e problem.

Liquid-Level Bu'o"ul_ers I._._...I 'The he1lu.m bilbbl-er i n s t r w n e n t a t i o n used f o r f u e l s a l t l&eJ_ instrumentation experienced a mechanical failure ir!. two 'The f a i l - u r e w a s a of tm d i f f e r e n t i a l pressure-sensing ri-nstruments l e a k y coimect;ion caused by weak w e l d m x i t s f a l i r i c a t e d by 'the vendor and used t o a'Gtach autoclave fiLLinss t o tine p r e s s u r e i n l e t t u b i n g . With t h e a s s i s t a n c e of t h e Me3;al.s and. Cerarni-cs Div-isLon, thc: weldxienti w a s r e designed and reweld-ed. No fuj-tiier d i f f i c u l t i e s have been experienced.

Weight X:o.striurienta'iion on S a l t Tanks. The system has no-k been e-0.The b a s i c input instrv;nien'l;a,kri.oii (weigh cel..l.s, mounttri.rel-y sa'Gisfactory ing, e t c ) has Bunctioiled s a t i s f a c t o r i l . y , b i h t h e readout has given t r o u b l e . Manometer readout i s acc omp1.li.shed by s e l e c t i n g a. p a r t i c u l a r weigh cel.1. chan.nel wiLh pneimatic s e l e c t o r v a l v e s . T'ne valves are composed of a s t a c k e d a r r a y of individ.iial. valves opera.t,ed by cams on %he opera,tri.ng handle s h a f t . The valves l e a k ; proposals t o e l i m i n a t e the problem a r e being cons ider? d "

Nuclear S a f e t y Instrumentation The e1ectron.i.c instruments hzve give-n-llttle t r o u b l e . The s o l i d - & a t e j-nodu.l.ar instrwrients, h i t h e r t o un'cried i n a n operating insta.l.l.ati.on, have needed- v-ery I l . t t l e seyvice, and, no major problems have developed w i t h use. Channel 3 of -tile s a f e t y system prod-i.i.ced, an abnormal nurnfcier o f spa-ious trips. A l a r g e nurlfoei- of G'nese a r e b e l i e v e d t o have origli.:m-t,ed i n f a u l t y v-ibratri-on-sensitiv-e r e l a y s in a commercial e l e c t r o n i c swi-Lch which provides t h e high-temperature trip signal in t h e channel. Vibrat-iofi i s o l a t l o n and s u b s t i t u i i o n of a d t f f e r e n t rela,y axe being consri.dei-ed a s p o s s i b l e anti-dates Another source o f occasional f a l s e t r j - p s i s believed. t o have o r i g i n a t e d wi.ti? a c h a t t e r ing of t h e rei-ays which change t h e sensitlivi-ty of t h e C 1 . i ~a m p l i f i e r s i n t h e s a z e t y c i r c i r i t s . T'his has been c o r r e c t e d . Very g e n e r a l l y t h e source of spurious t r i p s has been diffic1.i.l.t t o t r a c e , s i n c e .they a r e random and u s u a l l y appear -bobe i m r e l a t e d t o events elsewhere in the reactor sys.tElin A s e l . e c t r i c a l noise-pmdincing compoients elsewhere i n t h e system are elimina-Led, the number of false trcri-ps i s expected -tobe reduced..

Wide-Range -. Coun-ting Cba.nnel.s Moisture p e n e t r a t i o n has been experienced wi.i;h t h e wide-range comiti.ng channel "snake"18 assembly. A n ri.mg-mved. wateryroof jacket i s expectied t o c71re t h i s a f f l i c t i o n . il. fai.riS,y v e r n i s t a t and an overload-ed gear reducer rin -the d.r-iv-e urt1i.t or" t h e widerange counting channel mquired- replacement.

Linear Power Channe1.s and Servo C o ~ i t r - o l l e r The cornpensabed i o n chambers me a s m a l l e l e c t r i c motor t o change compc:nsa.tion. One motor drive has given some trouble and has been. responsibl-e f o r the main-ttnance r e q u i r e d by t h e s e chambers. The servo rod controller has been used f o r automatic conti-01- i n boLh the f l u x and temperature modes. Exce-ptimg tine pro'nkrn a s s o c i a t e d wi.t,ii t h e wide-range coi.l??i;ing channel, t h e s e r v o ' s p e r formance was very s a , t i s f a c t o r y I _

E l - e c t r i c a l Power Sys'cern. S u b s t i t u t i o n of t h e new 50-kva s o l i d - s t a t e _______..I converter f o t~h e e x i s t i n g 25-lcva motor geilerator i s expected t o ~red.i~.ce or el.imina'ie 1iiaIiy of Yrhe problems s ternmj.nS f?mm i n s t a b i l i t y , noise .andpoor vol.tage r e g u l a t i o n . ~

The i.nstal.l-ation of e x t e n s i v e rnoc~.ifieaticrns1' t o .the h t a - l o g g e r compu.ter was completed on A L J ~ U S2~1~ ~ 1965 and t e s t i n g bega.n imirediately Several f a i l e d computer coxponents 'were f oimd and ueplaced, azd two loose ccjunec Lions j.E the amLog i n p u t system were fowid and repaired. Additionnl. design cbaiges and adjv-stnien-ts were r e q u i r e d a s a r e s u l t uf th,e modifications, ;ri~~d-,wi.t;h t h e exception of t11.e d i g i t a l %ilter-iiltegr.ai;or, which requ.ired complete redesign, these changes and t w t i n g wcre compI.eted on September 1.6 The seven-day acceptance t e s t w a s restartxd on S::pi;e~~liser16, L%5> and ccrripleted September 23, 1.965. The re;inainder of SeQGember was spent c o r r e c t i n g miseell.a.neous 'naribrare problems, principa1.l.y l o o s e circw5t c a r d cormections AE. air-conditioning f a i l u r e caused- the cmputer r c ~ mambient temperature t o r i s e t o 85QF, and, sirriultaneou.sI_y, the a@ supply vol-tage Pe1.l to 103 V , These i x o conclitions, al.thoy$ sirnultzneoix, were r i o t coupled. I n t h e s e circu-wtances it was i w i p s s i b l e t o keep t h e system ox1 l i n e for more than a f e w hours a t a .%iuie 1% 'was conc:lv.ded that SLEcessful. o p e r a t i o n of the ccuiiputer requires that airfolient i;eup~r.xt;mi. be h e l d below 85'F znd that a c supply voltage be nLxiii-tafned b e t w e n 105 and 120 v. .)

. I

S a t i s f a c t o r y o p e r a t i o n was restored., and t h e system w a s accepted on October 1, 1-965, provided t h a t Bwker-Z!m-o Corporation (1)suppl-ies and i n s t a l l s a digitu1 f i l t e r - i r r % e g r a t o r f o r the ai.a,.l_og input signals I and. ( 2 ) provides and i n s t a l l s , at O I U L ~ S option, c:ircu.i.try wizicki prewents damz~get o t h e care mmory by r e s t a r t transients s.u-bsequent to a power Loss and which provides a control-1-ed sequence automatic restart when power is r e s t o r e d .

Octc'oer was s p l i t checkirg aid c a l i b r a t i n g iripuL inst-r7mentation a r i d i n troubleshooting hardware f a f l u r e s I p r i n c i p a l l y in the a:m.log i n put area of t h e system. I m t m i e n t cal.i.bratioris were e o q ~ l e t e din Novemli.-.r, as were si-ibstan:Itial rflodifieations t o improve rel.l.a?xi.7_i.-i;y scheduLeci by Bzu-hx-Hanno * T4ie digLtal. f i l t e r - i n t e g r a t o r and. resdar-t; c i r e u - i t r y were also instal.l_ed during t h i s sl~.i~tclown I n t h e period of December 1965 t h r o u g h Febr-txq- 19625, the 1.ogg:ercmputer achieved o p e r a t i n g status. 111 a d d i t i o n to t h e roukj.n.C and -pertodic co3_7_ectionof o p e r a t h g &xi;ol, it ifas used Go obtain .tm,nsienit and. frequency responses m d to determi-ne fixe1 t e n i p e r a h r e c o e f f i c i e n t s of reactivity. It was p r o g r a m e d t o o p e r a t e t h e cori-trol rod for t h e

pseudoraridcm biriary t e s t s r e p o r t e d i n "W%& Dym.nrLc T e s t s " t11i.s report. 'T'he l o g of u p r a t i n g & x t a , vhich did not seein signific'w-t; d . u r b g operation, b e c a e extremely u s e f u l during a n a l y s i s of the off-gas problema Dming t h i s p e r i o d t h e various corn:putkig 2kD.d logging progrmi~swere being mod5fied i n accor&,rice with the requirements devel.oped &ring ~cactorope-ramti on.

50 Figure 1 . 2 2 chayts, on a weekly b a s i s , t h c I t i n service'' or rronrr-Lime as a percent of t o t a l ' ~ T n i e . The shaded a r e a s on t h e f i g u r e a r e scheciul-ed shu-tdowns and cannot be charged 3gains'L t%re system as ma1fmictA.on.s. U m ~ . a g t h e period. immediateI.y following system acceptance, p e r f o-mance, as noted above, w a s d i s a p p o i n t i n g l ~low aiid d i d ilot approach t h e s p e c i f i e d rcq,Lirements. The system has shown a s l o w b u t steady o v e r a l l iniprovEment ?'.xi ope r a t i n g relAabi1i'Gy as debugging progressed. For example, d-ixing li'ebruary the logger-computer " i n s e r v i c e " time was 99.7%.

MSHB Training Simulators The po?fer level- t r a i n i n g s i m u l . a ' c o ~was ~ ~ ~operated successful-ly i n Oc-Lo>Der1'365 as p a r t of t h e o p e r a t o r - t r a i n i n g program, It w a s s e t up on two general.-pur.pose, p o r t a b l e EAI-'I?R-I.O analoe compu'r;ers and.t i e d i n with he reac-Lor instrumen-bation system. No s p e c i a l hardware was reqixired The c o n t r o l of the simiL.ator was effected entire1.y from t h e o p e r a t o r ' s console, where actual- rod motion, radiator door p o s i t i o n i n g , and blower

OQNL~DWJG6 6 - 2 6 2 2

100

lNTEGRAIED "ON" TIME

* - 3 6 98

' O N TIWE

@ 70

n SCHEDULED SHUIDONNS FOC: MAINTENANCE OF PERIPHERAL EQUIPMFNT

â&#x201A;Ź0-

-z

SLHEDULED SHUTDOWNS FOR MAINTENANCE AND MODI F I C A 1I GNS

"' 5

50-

OCT 1 I

NOV 5

DEC 3

JAN 7

FEB 4

MAR 4 I

F i g . 1.22. A v a i l a b i l i t y Record of' MSlU D a t a System,October 1955 to February 1966, I n c l u s i v e I

Doc t ion -men%a ---

Excegt f o r sone r e v i s i o n s and adriitions t o instrtmient s p e c i f i c a t i o c sheet and p r e p a r a t i o n of a design report;, documen1;ation of t h e PEP3 i n s t r u m e n t a t i o n and COD-trolssystem d e s i g n i s cornFIe-te. D u r L r q the. past r e p o r t period, instrummil; apF1ication and switch tabul-atioils were cornp l e t e d and issued, and design drzwings were revised- to incorporate asb u . i l t r e v i s i o n s and r e c e n t a d d i t i o n s to and r e v i s i o n s of the sys.t;eni.

Ref ere nc e s

K, L. ' 2 . Hanipton, Simulation 4 ( 3 ) , 17'3-90 (1965).

PfiR Program Xcmiancl. P ~ - G ,Rcpt. ~ I - ~Auz. 31, 1765, OKNL-3872,

11. H. Guymon, YERX Design and. Operations Report, Part? V I I l . , Dyerating Procedures, v o l . 1, OXNL-TM-908 (Uecem'oer 1.965).

8. MSK P r o g r m Serniann. Progr, Rept. Aug. 31, 1.965, ORNL-3872, 10. TGR Program Serfliam. Progr. Rept. A=.

p. 22.

$13.

118-j-9.

31, ---19615 .-.-) ORNL-3t372, p. 43.

11. S . E . Xea3-1 e t a l . , â&#x201A;ŹGLWDesign and Operatioris Report,, P a r t V, Kea c t o r Safeby Analysis Ileport, ORBL-TM-732, Fig* 2.27, p. 92, pp. 10(3-'101. 12.

I'oid., ---

p . 104.

52 13.

ibid., ---

pp. l O ~ , l 2 .

14.

Ibrid., -

p. 100.

15. -a.. i .d ...... , p. 98, F7.g. 2.27.

16. R. B. kiriggs, Status of 'chc Problem of P!-i~&ng i n t_.h-- e Off-Cas Lines in the MSRE, NSR-66-3 (Max, 1.,"1-966) (internal use only].

17. See Chap. 2 of Ynis r e p o r t . lis.

MSK Piwgmm Semiann. ..d ._.. : 1965, ::-ORNL-3872, p. 38. .-......,_. .... Progr. R e p t . A m . I.31 ~

19. Ibi.d., p . 40.

The effo-As o f t h e development group wsre devoted t o a s s i s t i n g i n t h e prepower. opera-Lion and t e s t i n g of the reactor. Several changes i n t h e equipment and procedures were :made, and these are described- bel-ow. Freeze Valves

1 _ -

The spe(::ificati.ons for all but Chree of tlie freeze valves were s i r n pli.fied by e l i m i n a t i n g t h e "rapid." thaw requ.iremenL. Tnis requirement i s needed i n FKl.03J which controls t h e emergency d.ra-i.n o f the reactor, and i n FV204 and FV206, which c o n t r o l the emex-geney drain of the cool.ant, system, but h a d been included i n the remaFning valves only as an operat i o n a l convenience. Since t h e maintensrice of .the proper temperature d i s t r i h u t i o i i needed t o en.~i~.:rea rapid thaw was rrrore dli-i"ficu.lt '~hanwas cons i s t e n t w i - t h good- operatir.ig p r a c t i c e , t h e r a p i d thaw requireitlent wa:3 .? and Y l e s e valves are now operated. e i t h e r i n the thaw$ed or deep-frozen condition. The valves which niigiit corxLain siriTLci.ent, radioa c t i v i t y i.n t h e s a l t -Lo produce rad.i.ol.yi;ic f l u o r i n e a t low teniperature s a r e maintained abow 4013"F a,+: all t i t l i e I;. Experj-ence tii-th the i n - p F l e experiments and o t h e r test::: have sho~wntha1; esoentia1l.y no fhior?-.ne is released above t h i s -1;einperature.

Control rod i u i t s I and. 2 have operated wj.thout difficu1'c;y since t h e i n i t i a l i n s t a l l a t i o n a t the macl;or. Exa.mina-tion OP rod 3 a t tlie end- of t h e cri.tricali.by t e s t s revealed. that the br.aided :fir.e shea.%ln had. beei? t o r n a-t a poind; 28 i.n. below the .tow block. The imT-er convoluted ho:;e was worm but rio1; comple'cely tbrrough Yne wall. Cause of t h e darnsge appeared t o be l A e upper r o l l e r i n the cozi.tro1. rod ".M.nible, whlich h8,d jammed. avld w u l d n o t robate. Tfle rcoller had a galled- Tlat area on one side. 'The th2mbl.e 1-oller and.u.pper c o n t r o l rod hose were replaced.. R e c e n t exasllinat i o n .i.nili,cated no A % r t h e r difficiilty after s e v e r a l months of o p e m t l o n 9.1; tenrpe ratllre

54 Control Hod Drive Uni-ts The-mal switches were i n s t a l l e d i n tiie lower e-nd and a r e s e t t o a1.am when t h e temperature r i s e s above through t h e d r i v e uiiit c a s e s i s about, 1.4 sci'm, whj.ch quate t o maintain t h e temperature wi'cliin t h e housings

of t h e d r i v e housing 200째F. The ai.r fl.ow appears 'GO be adea t 163s:: t h a n 200째F.

It w a s necessary t o r e p l a c e t h e No. 3 d r i v e u n i t isecainse t h e p o s i t i o n indica-Lors revealed a!?. 0.8-in. deviatri-on fyom t h e o r i g h a l zero s e t p o i n t . "lie dev:atri.on w a s caused by a parkially r c s t r i c k e d sprring a c t i o a of t h e preload s p r i n g operator of Tile d.rrive chain. Thri s al.lowed enough slack i n t h e d.ri.ve chain t o permit thc chain l i n k s t o slip over t'ne sprocket g e a r t e e t h . The ~n-i.1~ continued t o operate wi-Lliout d i f f i c u l b j with the 0.8-<.n. e r r o r u n t i l replaced. Yi?e lower 1-i.mi.t switch of u n i t No. 3 showed an. i n t e m i i . t t e n t tendency t o s t i c k ~ ~ I i e-the i i conti-03. i ? O d was d-ropped from above 24 i n . 'The swit.ch could be r e l e a s e d by f i l l y withdrawing tile control. rod. W e found. t h a t tiie shock absorber s t r o k e w a s 25% g r e a t e r -khan normal when t h e control. rod was dropped from 51 i n . The-re i.s evi.d.ence t h a t t h e i n e r t i d of -the switch a c t u a t i n g arm w a s s u f f i c i e n t , when t h e conti-01. r o d was dropped from 51 i n . , t o ovexorne t h e force of the a c t u a t o r r e c o v e q s p r i n g t o a p o i n t where t h e lower end ol" t h e actuatj.ng m d cou2.d s t r i k e t h e lower flange of t h e d r i v e u n i t . T'he aci;.uaiing rod had- been sl.i.ghtly bent due t o s t r i k i n g tiie flanze, causing it t o bind i n t h e guide bushing. A s-tro spring w i l l be iiis-i;al.l..ed. -to preven-t t h e o v e r t r a v e l . Figure 2.1. i.s a, photograph of t h e c o n t r o l rod d r i v e u n i t s i n p o s i t i o n on t h e reacLor. ' l h e s h i e l d i n g and access h a t c h have been removed, showing t h e a3.r a n d - electrical disconnects i n t h e d r i v e u n i t covei". When a i1nri.t i s removed,-t,he srnal.1. hatch on t h e &rive u n i t cover i s removed (note uni-L No. 2 i n Fig. 2.1), which permits access Lo t h e c o n t r o l r o d tow block f o r re1eai;In.g the c o n t r o l rod from t h e d r i v e u n i t , and also access t o tiie lower d r i v e u n i t flan.ze foi- r e i k a s i n g t h e di5ve 1mi.t t r o m t h e thimble fl-a-nge. T'nis method of removal has been utilized foi* cmn.tro1. TO& maintenance s i n c e t h e i n i t i a l . instal.l.at,i.on a t t h e reactor.

Thermal warpirig of tile r s d i a t i o n d o o r s and door s e a l s p e m i t i e d a i r t o Jeak t'nrough t h e r a d i a t o r enclosure ai a n nxcessive i a t c , and m o d i - f i c a t i o n s had i o be madp t o r e d u c e t h e leakage. The fol.lowiiig modifications w e r e made (Fig. 2.2 shows tile face of the r a d i a t o r with t h e 3.nl.e'~ door rai.sed a f t e r r e p a i r s and m o d i f i c a t i o n s ) :

I-.

The d.oor t r i p locks. The l o c k s were c:odiYied and. a d j u s t e d s o t h a t , wherr t h e door was f u - l l y closed, t'he t r i p locks forced Lhe metal door, by a -Por.warci. c m ? . n g action, agarlnst t h e s o f t seal. on t h e Y a r x OP the r a d i a t o r enclosure. The forward. rorce i s e x e r t e d by rnovemni; o f tile d o o r i n t h c downward d i r z c t i o n i n t o the rolling cam l o c k s l o c a t e d on the r a d i a t o r frame.

CONTROL-ROD ACCESS ATCH REMOVED

CKUP BAIL CESS HATCH FOR IVE-UNIT AND

7 CONTROL-HWU-LUULINb AIR-SUPPLY DISCONNECT

-A

/ COOLING-AIR-SUPPLY ’

DISCONNECT

3 _c

F i g . 2.1.

Control Rod Drive Units i n Operation P o s i t i o n a t MSRE.

F i g . 2.2.

I n l e t Side of Radiator Door i n Raised P o a r t i o n .

2. Door guide t r a c k s .

The door moved t o o c l o s e t o t h e r a d i a t o r s e a l s when i t w a s r a i s e d o r lowered. Warpage of t h e door caused some of t h e s e a l elements t o hang on t h e door, and they were t o r n l o o s e . The p o s i t i o n of t h e door t r a c k w a s moved t o provide 1 i n . of clearance between t h e s e a l s and t h e face of t h e door when t h e door w a s r e l e a s e d from t h e f i l l y closed p o s i t i o n .

C a m follower b r a c k e t . The doors tended t o drag and jam i n t h e guide Cams had been i n s t a l l e d i n t h e t r a c k s t o f o r c e t h e doors away tracks. from t h e s e a l s when t h e y were n o t f u l l y closed. The cam follower b r a c k e t s are mounted on t h e doors, and contain r o l l e r s which r i d e on t h e t r a c k cams. These r o l l e r s were damaged by t h e wedging a c t i o n of t h e t r i p l o c k s a g a i n s t t h e door r o l l e r s and t r a c k s when t h e doors w e r e dropped i n t o t h e closed p o s i t i o n . The cams were changed t o provide clearances of 1/8 i n . between t h e r o l l e r s and cams when t h e doors were closed. A s h o r t movement of a door i n t h e upward d i r e c t i o n b r i n g s t h e r o l l e r i n t o c o n t a c t with t h e cam, f o r c i n g t h e door away from t h e soft seal.

4. End r o l l e r s were i n s t a l l e d on t h e cam follower b r a c k e t s t o prevent s i d e motion from jamming t h e doors a g a i n s t t h e t r a c k s .

5. R e l i a b l e o p e r a t i o n of t h e l i m i t switches i s important i n reducing t h e

number of ways i n which t h e doors can malfunction, and t h e o r i g i n a l switches were not very r e l i a b l e . New heavy-duty switches and a c t u a t o r s were i n s t a l l e d t o o b t a i n more p o s i t i v e a c t i o n . An a d d i t i o n a l upper l i m i t s a f e t y switch w a s added p l u s a mechanical "hard stop" above t h e added upper l i m i t switch. I n t h e event of complete switch f a i l u r e t h e door s t r i k e s t h e ''hard'' s t o p and an overload switch s t o p s t h e d r i v e motor before t h e door s e a l s can be damaged.

6. The door p o s i t i o n i n d i c a t o r s are synchro-driven devices l o c a t e d on

t h e d r i v e s h a f t s . The doors a r e l i f t e d by s t e e l c a b l e s which a r e wound and unwound on chain-driven sheaves on t h e d r i v e s h a f t s . If t h e doors jam while b e i n g l o w e r e d , t h e sheaves continue t o t u r n and Continued acgive i n c o r r e c t i n d i c a t i o n s of t h e t r u e door p o s i t i o n s . t i o n o f t h e d r i v e u n i t , a f t e r t h e doors have stopped moving, causes t h e l i r t i n g c a b l e s t o unwind from t h e sheaves and attempt t o rewind i n the reverse d i r e c t i o n . The c a b l e s u s u a l l y jump out of t h e grooves i n t h e sheaves and become s n a r l e d and kinked.

A "loss-of-tension" device has been designed b u t not i n s t a l l e d which w i l l s t o p any a c t i o n of t h e d r i v e u n i t should t h e c a b l e s become s l a c k . It i s simply a switch which w i l l be a c t u a t e d by movement of t h e cable from i t s normal t i g h t e n e d p o s i t i o n .

7. When t h e clearance between t h e door and door s e a l s w a s changed t o 1

i n . with t h e door open ( s e e No. 2 above) it w a s necessary t o provide a d d i t i o n a l clearance between t h e door and t h e r a d i a t o r enclosure hood. The hoods on both i n l e t and o u t l e t doors were s h i f t e d 1-1/2 i n . t o provide t h i s clearance.

57 Radiator Heater E l e c t r i c a l I n s u l a t i o n F a i l u r e The e l e c t r i c a l 1 s from t h e r a d i a t o r h e a t e r s extended v e r t i c a l l y nclosure and terminated i n j u n c t i o n boxes on up through t h e radiat t h e floor of t h e area een t h e r a d i a t o r hoods. These l e a d s a r e ds. The e l e c t r i c eads extending f r o m t h e i n s u l a t e d w i t h cerami ly and c o n t r o l c i r c u i t s were p l a s t i c - i n s u l a t e d j u n c t i o n boxes t o t h e wires which were r a t e d for 14O'F. Heat l e a k s up through t h e r a d i a t o r enclosure along t h e wire bundles overheated t h e j u n c t i o n boxes, and t h e p l a s t i c i n s u l a t i o n melted. The h e a t leakage i n t o t h i s a r e a was reduced by welding t h e o r i g i n a l sheet-metal enclosure wherever p o s s i b l e , by patching some openi by r e i n s u l a t i n g . The j u n c t i o n boxes were removed from t h e high a r e a between t h e hoods t o a c o o l e r p o s i t i o n on t h e e a s t w a l l of t h e pente . E l e c t r i c a l wire extensions between t h e r e l o c a t e d junction boxes t h e beaded h e a t e r lead w i r e s were i n s u l a t e d w i t h 194'F thermoplastic i t i o n . Figure 2.3 shows t h e p r e s e n t arrangement of t h e h e a t e r wiring between t h e hoods over t h e r a d i a t o r doors. Increased

Encl

2.3.

d i a t o r Door Shrouds and

of Radiator

58 c i r c u l a t i o n of c o o l i n g a i r i n t h a t a r e a w a s provided by r e r o u t i n g some of t h e e x i s t i n g exhaust d u c t s . Cool a i r i s d i r e c t e d downward through t h e d r i v e mechanism i n t o t h e h e a t e r l e a d area; exhaust ducts remove t h e heated a i r from t h e f l o o r between t h e hoods. The s o u t h exhaust duct can be s e e n i n F i g . 2.3. There a r e two a d d i t i o n a l exhaust ducts on t h e n o r t h end of t h e area; t h e s e are 1 0 - i n . - d i m f l e x i b l e t u b e s . &so a duct w a s i n s t a l l e d between t h e door hoods s o t h e hoods w i l l be cooled when t h e main blowers a r e running. The average ambient temperature i n t h e a r e a between t h e doors a f t e r t h e above modifications w a s approx 100째F w i t h t h e blowers o f f . Temperature w i t h i n t h e beaded e l e c t r i c a l l e a d bundle p e n e t r a t i o n s a t t h e t o p of t h e r a d i a t o r w a s 600째F w i t h t h e blowers o f f . These temperatures a r e sati s f a c t o r y , and t h e temperatures a l s o were s a t i s f a c t o r y w i t h t h e blowers on.

Sampler-Enricher During t h e shutdown p e r i o d following run 3, t h e low-power experiment, s e v e r a l modifications were made t o t h e sampler-enricher t o i n c r e a s e t h e e f f i c i e n c y of o p e r a t i o n . Most of t h e s e were d i s c u s s e d i n t h e previous semiannual r e p o r t . ' The major m o d i f i c a t i o n s made a t t h a t time included: (1)r e p l a c i n g t h e removal valve w i t h a modified v e r s i o n , ( 2 ) adding a knob t o one l i n k a g e p i n of each a c c e s s p o r t o p e r a t o r t o a i d i n opening it w i t h t h e manipulator i f it should f a i l t o f u n c t i o n p r o p e r l y , ( 3 ) putt i n g s t e e l r i n g s i n t h e convolutions of t h e manipulator i n n e r boot t o h o l d it f r e e of t h e manipulator arm, and (4)adding a p r e s s u r e switch t o prevent a n excessive p r e s s u r e g r a d i e n t a c r o s s t h e manipulator b o o t . The manipulator arm which w a s bent during r u n 3 w a s r e p l a c e d . The hand w a s s t r a i g h t e n e d , and a 1/4 X 1/4 i n . p r o j e c t i o n w a s welded t o t h e bottom of each f i n g e r t o a i d i n handling t h e capsule c a b l e . Clearances i n t h e Castle j o i n t were i n c r e a s e d t o reduce t h e f o r c e needed t o operate t h e manipulator. A d d i t i o n a l changes have been made t o improve t h e r e l i a b i l i t y of ope r a t i o n . The b r a s s keys used t o a t t a c h t h e capsules t o t h e l a t c h were r e p l a c e d w i t h n i c k e l - p l a t e d mild s t e e l keys. I n c a s e a capsule i s dropped it can now be r e t r i e v e d w i t h a magnet.

Two changes were made i n t h e i n t e r l o c k c i r c u i t . A p r e s s u r e switch i n s t a l l e d on t h e manipulator cover r e q u i r e s a negative p r e s s u r e i n t h e cover b e f o r e t h e o p e r a t i o n a l o r t h e maintenance valve can be opened. Also, both t h e o p e r a t i o n a l and t h e maintenance v a l v e s m u s t b e c l o s e d bef o r e e i t h e r t h e a c c e s s p o r t or t h e removal valve can be opened. These changes were made t o ensure t h a t t h e r e i s double containment a t a l l times. I n s t a l l a t i o n of lead s h i e l d i n g around t h e sampler-enricher has been completed. Ten inches of lead or t h e e q u i v a l e n t w a s i n s t a l l e d around t h e main components and 4 i n . around t h e off-gas system. While t h e rea c t o r w a s o e r a t i n g a t 1 Mw, t h e r a d i a t i o n l e v e l around t h e equipment w a s < 1m r h r .

During r u z s 4 and 5, 40 smpI.es were t a k e n , 9 of which were 50-g samples for oxygen a n a l p i s i n place of t h e us~zal10-g S x r i p l e E . %TO of the l a r g e capsules f a i l e d t o t r a s a s a n p l e . The f i r s t assed~lyw a s n o t l o n g enough t o submerge t h e :fil.l. opening of t h e c a p r i l e in salt i n the pimy bowl. A l l ot'ner assemblies were made l o n g e r . The second f a i l . u e t o t r a p a sample pro'ua-tiPj r e s u l t e d from the c:zpsule c a t c h i n g on the l a t c h s t o p ai; -i;ne top of t h e p~uiip and not e n t e r i n g t h e purrip ?oowl.. The capsule has been modified s l i g h t l y t o make it hang s t r a i g h t e r and i s -Lherefore less a p t t o hang. While withdrawing orie of t h e I O - g capsules, t h e p o s i t i o n incEca2tcir stopped,, i n d i c a t i n g -that -t'ne capsule had 'fmng or t h e ca21l.e had ,jarmed. After r e p e a t e d atteiiipts, t h e c a b l e w a s withdrawn comphAx?ly. The ca'o1.e wits exmrrrined t o determine t h e cause of t r o u b l e . A p p r e 0 t l . y t h e capsule or l a t c h had hung on t h e g a t e of the maintenance o r o p e r a t i o n a l valve taming the cable .to c o i l q . The c a b l e a l s o backed up i n t o %'Lied r i v e u n i t box and caught in the motox' g e a r s . The cab1.e w a s s t r a i g h t e n e d , the operi l i m i t switches on t h e o p e r a t i o n a l and nlaintenance v:zl_ves wilre res& t o o p n t h e v a l v e s wider, and tlie outside c3rianeter of the Latch w a s r e duced. No si.milar trouble has been experienced.

nie a q u i l i b r i w n buffer p r e s s u r e t o t h e o p e r a t i o n a l valve dropped from 55 to 35 psia during one sampling o p e r a t i o n . T h i s r e p r e s e n t s a leak of ab0v.l; 29 cc He/miiz tlrrough Yne s e a l on Yne tipper g a t e of t h e v a l v e . A p a r t i c l e of s a l t o r metizl appareritly dropped 012 t h e gate while t h e capsule was being rexoved o r a t t a c h e d t o t h e Latch and Lodged b e tween t h e gate and t h e s e n t . Repeated e f f o r t s to blow -LIE pa,r-ti.cle from the sealing surface have f a i l e d . T'he l e a k rate h a s not increased w i - L h continued use. 'I3e l e a k of helium from t h e buffer system i s IEainly an inconvenieme, a s it slowly p r e s s u r i z e s t h e vol.wne above the valve,,and t h e gas mixst be vented -Lo t h ~ au;til.i.ary : c h a r c o a l bed about once a day. Besides th-is seal, t h r e e more s e a l i n g surfaces between t h e pwiip i 3 0 ~ 1and t h e sample access area provide a d e y m t e safety; t h e r e f o r e Yne valve wU1_ nc't 'ne r e p l a c e d a t t h i s time.

The smgile capsule used while t h e r e a c t o r was operating ut 1 W , 1ef-k c o n s i d e r a b l e corxtmiination i n t h e t r a n s p o r t coatainer 'The o:pen end of the bot-torn cup r e a d LAI r / h r near c o r r ~ a c ta f t e r t h e capsule 'TN'ZS removed. lieplaceable l i n e r s have been f a b r i c a t e d t o r e d w e %be ccxitL7;mination l e F t i n t h e trarisport container.

Coolant Salt Sampler

During runs 4 and 5, t e n samples were i s o l a t e d from the coolant pwnp bowl, two of w-hich were 50-g s m p l e s . D i x i n g o m smglirg. the l a t c h f a i l e d t o s l j d e freely -through t h e transfer .tube. Iqo reason for t h e d i f f i c u l t y could be found, b u t t h e oixtside rJiameter of t k l a t c h was reduced t u l e s s e n t h e possibili-by of future trouble.

D u r i n g t h e shutdown period following run 3 a capsule was ].eft hangi n g on t h e l a t c h . A dry helium atmosphere was maintained i n t h e sampler.

60 When t h e capsule w a s r e t r t e v e d from t h e pump bowl i n L a k h g t h e f i r s t sample of run 4 (CP-4-1), a lol-ack film covered t h e sal.:; and adhered t o t h e o u t s i d e of t h e capsule. The film w a s i d e n t i f i e d . as decomposed o i l . Ano t h e r smiple t a k e n 4 hr Later was c l e a n w i t h no evidence of black f i l m . The sampler w a s opened and examined f o r o i l contam.i.na,kion. A sma1.1. amount w a s found on t h e t o p f l a n s e of t h e glove box near the elastomer g a s k e t . No evidence of o i l w a s f o u n d around t h e d r i v e 1mri.t o s capsule. The source of t h e o i l w a s not l o c a t e d , b u t subsequen-L samples have been f r e e of t h e f i l m .

Examination _I_._...._.-... -. of Components from t h e E X E O f f -Gas System I _

The d i f fri cul-ty with plugging axid p a r t i a l . r e s t r i c t i o n in the $ERE off-gas system i s described i n t h e s e c t i o n on systems nerfomance . Seve r a l of t h e components which had given t r o u b l e during -tihe e a r l y operation at, 1./2 and 1 Mw were removed t o t h e KKLFL f o r examination. Photographs were taken through periscopes, a n d many samples of t h e f o r e i g n m a t e r i a l found i n t h e comyJonents were removed a,nd t r a n s f e r r e d t o t h e a n a l y t i c a l chemistry hot c e l l s f o r aiial-ysis. The resul-Ls of t h e s e analyses are r e p o r t e d i n t h e s e c t i o n on chemistry. A siimary of t h e v i s u a l examinations 1riad.e i n

HRLEL i s given

belO>T.

Capillary Flow R e s t r i c t o r FE 521 ... _. ... The flow r e s t r i c t o r consi.sts of a s h o r t length o f 0.08-ia.-IDtubing welded i n t o t h e l i n e at, one end and- c o i l e d t o f i t i n s i d e a 3-in.-ID cui-1a i n e t - . The o t h e r end of t h e l i n e i s l e f t f r e e The c o n t a i n e r was c u t open, arid t h e entrance and e x i t ends of t h e r e s t r i c - t o r tubing were examined. The entrance region w a s clean, and o n l y a small- d e p o s i t w a s found on t h e c o n t a i n e r wall near the end of t h e discharge region. This deposit i s showri i n Fig. 2 . 4 . The res-i;rict,or WRS nCJt coipl.e?xly plug@when examined i n t h e hot cel.1.. L

Check Valve CV 533 ._ ..._. .... The check valve i s a sma1.l. spring-loaded poppeL-type Val-ve i n s t a l l e d i n t h e gas l i n e t o prevent a backflow i n t o t h e f u e l pump gas space dii.ring t h e ventling operatton on t h e d r a i n t a n k s . Some roreign m a t e r i a l was found on exnmina-tion of t h e poppet, bu-i; Y h i s w a s no-i; sufficient to s t o p t h e gas flow. Yle valve poppet i s shown i n F i g . 2.5, and f o r t h e p - u p o s e o f t'ne examinatiion j.s shown i n t h e oyei: posi.l;Lon. The soft 0-riiag T , r h i c h makes t h e s e a l can a l s o be seen i n i-Ls normal posit;.i.on on t h e poppet. The o-Lher material on t h e cone of tlne poppet i s ai1 amber var'nisii-lj.ke m a t e r i a l , which w a s i d e n t i f i e d as a hydrocarbon. Charcoal Bed. Tnl.et Val-ve HV 621 . .. ._ ._ _.._ T n e valve examined was one of f o u r which c o n i r o l the gas flow into each of four p a r a l l e l charcoal s e c t i o n s which makc up t h e main charcoal

61 bed. The valve had given i n d i c a t i o n s of almost complete plugging b e f o r e removal from t h e system. The v a l v e w a s c u t a p a r t w i t h a s a w i n t h e hot The small m e t a l l i c c h i p s c e l l , and t h e valve stem i s shown i n F i g . 2.6. shown near t h e l a r g e end of t h e cone a r e f r o m t h e sawing o p e r a t i o n . The e n t i r e cone w a s shiny as though wet w i t h an o i l l i k e m a t e r i a l . There w a s some white amorphous powder on t h e t a p e r e d s e c t i o n of t h e valve t r i m .

Fig. 2.4.

Deposit i n Flow R e s t r i c t o r FE 521.

F i g . 2.5.

Check Valve CV 5 3 3 .

F i g . 2.6.

Charcoal Bed I n l e t Valve Stem HV

The powder seemed t o be adhering f a i r l y s t r o n g l y t o t h e metal surface, although t h e r e were some d i s c o n t i n u i t i e s . A similar m a t e r i a l w a s found i n t h e valve body. The g e n e r a l appearance of t h i s a r e a i n d i c a t e d t h a t t h e powder had moved up and t h t h e motion of t h e valve stem and w a s t h e r e f o r e not small s t r o k e of t h e valve. Samples for analysis. of t h e white mate

Line 522 Pressure Control Valve PCV 522

PCV 522 c o n t r o l s t h e gas overpressure on t h e r e a c t o r system by varyi n g t h e gas letdown (off-gas f l o w ) . The flow passage a t t h e valve s e a t w a s q v i t e s m a l l (about 0.010 i n . ) i n order t o c o n t r o l t h e r e l a t i v e l y low gas flow (4.2 l i t e r s / m i n ) . The valve w a s mounted w i t h t h e s e a t above t h e stem. Flow w a s down through t h e s e a l ( r e v e r s e of normal). The valve stem was c o v e r e d w i t h an amber o i l l i k e coating, and t h e r e w a s an accumulation of f l u i d i n t h e r e c e s s formed by t h e bellows-to-stem adapter p i e c e as shown i n F i g . 2.7. The t a p e r e d f l a t (flow a r e a ) on t h e stem had s m a l l accumulations of s o l i d m a t e r i a l . The valve body w a s coated w i t h s i m i l a r m a t e r i a l and had a semisolid mass of m a t e r i a l on t h e 5urf a c e near t h e s e a t p o r t a s shown i n F i g . 2 . 8 . Samples of t h e s e m a t e r i a l s were removed f o r analyses.

I -

Fig. 2.7.

PCV 522 Valve Stem.

Fig. 2.8.

PCV 522 Valve Body.

64 Line F i l t e r 522 F i l t e r 522 i s a 1-in.-diam 'by 15-in.-long c y l i n d r i c a l type 316 s t a i n Less s t e e l s i n t e r e d metal element i n a 1-1/2-in. ( i r o n pipe s i z e ) pipe housing. Element thickness i s 1/16 i n . Flow i s from t h e outside i n . The f i l t e r a r e a i s 0.34 f t 2 , and t h e removal rating i s 9% p a r t i c l e s > 0.7 p . The p r e s s u r e drop ( c l e a n ) a t 4.2 l i t e r s / m i n helium (normal MSRE flow) i s 2 i n . H2O. The f i l t e r w a s i n s t a l l e d immediately upstream of t h e r e a c t o r gas p r e s s u r e c o n t r o l valve (PCV 522) t o p r o t e c t t h e very f i n e valve t r i m . The f i l t e r assembly w a s removed from l i n e 522 on February 8, 1966. I n i t i a l v i s u a l examination w a s made a t HRLEL on February 9, 1966. The upper o n e - t h i r d of t h e element w a s l a r g e l y s t e e l gray i n appearance. A s shown i n F i g . 2.9, t h e s t e e l gray a l s o appeared i n t h e lower p o r t i o n a t t h e seam weld and i n a few i s o l a t e d s p o t s . The major p o r t i o n of t h e lower two-thirds of t h e element had a f r o s t y white appearance. A t no place w a s t h e r e any evidence of a measurable buildup, o r cake, on t h e f i l t e r surface. Visual examination was continued on February 10, 1966, a t which time it w a s noted t h a t t h e f r o s t y white a r e a s had become darker i n appearance, tending toward t h e s t e e l gray. I n s p e c t i o n of t h e i n t e r i o r of t h e f i l t e r housing showed an accumulation of f o r e i g n m a t e r i a l i n t h e bottom as shown i n F i g . 2.10. Samples were scraped from t h e s i d e of t h e element, The f i l t e r was then reassembled, and a flow pressure drop t e s t (see below) w a s run on February 11, 1966. The f i l t e r was once again disassembled, and t h e element w a s s e c t i o n e d i n t o s h o r t p i e c e s . The f o r e i g n m a t e r i a l i n t h e bottom of t h e housing was removed r e a d i l y by r i n s i n g w i t h carbon d i s u l f i d e

R27776

F i g . 2.9.

F r o s t y Deposits on t h e Surface of F i l t e r 522.

65 R27814

Fig. 2.10.

Deposit i n t h e Bottom of F i l t e r 522 Housing.

Flow Test on t h e MSRE F i l t e r from Line 522 The f i l t e r and f i l t e r housing which had been removed from l i n e 522 on February 8, 1966, w a s t e s t e d i n t h e h o t c e l l of t h e HRmL as i n d i c a t e d i n t h e flow diagram given i n F i g . 2.11, and flow t e s t s were conducted on February 11, 1966. The gas w a s discharged i n t o t h e gas d i s p o s a l f i l t e r system of t h e h o t c e l l . By t a k i n g readings of t h e f i l t e r pressure gage through t h e hot c e l l window for v a r i o u s helium flow r a t e s t h e r e l a t i v e plugging of t h e f i l t e r w a s determined. The data obtained a r e shown i n F i g . 2.12. The graph a l s o shows t h e r e s u l t s of a helium flow t e s t conducted on a d u p l i c a t e b u t c l e a n f i l t e r . The data i n d i c a t e t h a t f o r a given p r e s s u r e d i f f e r e n c e t h e 522 f i l t e r w a s passing only 5% of t h e corresponding flow of t h e c l e a n f i l t e r . However, e x t r a p o l a t i o n of t h e data t o t h e normal MSRE off-gas flow i n d i c a t e that, even though 95% plugged, t h e c o n t r i b u t i o n of t h e f i l t e r (0.075 p s i ) t o t h e t o t a l system pressure drop ( 5 p s i ) w a s n e g l i g i b l e .

Fuel Processing System Sampler The mockup t h a t w a s used t o develop t h e sampler-enricher f o r t h e RE i s being modified and w i l l be i n s t a l l e d as t h e sampler f o r t h e f u e l

ORNL-DWG

66-4754

DISCHARGE

I :

I I

1 1 I

!-FILTER

I 1

ASSEMBLY NO. 522

I 1

SINTERED M E T A L PREFILTER

REMOVED FROM M S R E L I N E 522

HOT C E L L

H E L I U M SUPPLY

F i g . 2.11. Test Arrangement a t Building 3525 Hot C e l l . Flow vs pressure-drop t e s t . F i l t e r No. 522 removed from MSRE on Feb. 8, 1966.

DRNL-DWG 66-4755

HELIUM FLOW RATE (liters/rnin/ft2)

Fig. 2.12. Flow vs P r e s s u r e Drop. MSRE f i l t e r No. 522. element: P a l l T r i n i t y t y p e G. 316 ss s i n t e r e d metal. Area:

Filter 0.34 f t 2 .

67 processing system. Design of t h e modifications t o t h e rnechanical equip1iient i s f i n i s h e d except f o r t h e s h i e l d i n g . Modifications to t h e equipment t o upgrade it f o r 15-psig s e r v i c e are n e a r l y corflplete. Redesign of t'ne i n s t m n e n t a t i o n i s complete. This work involved some r e v i s t o n s t o panel and f i e l d instrwrientation, some changes i n c o n t r o l c i r c u i t r y , p r e p a r a t i o n of i n s t a l k t i o n and i n t e r c o n n e c t i o n dxawings r e q u i r e d t o i n s t a l l t h e system a t t h e MSLSF: s i t e , and r e v i s i o n s of nomenc l a t u r e and numbering of instruments and c i r c u i t s t o conform w i t h t h e MSRE p r a c t i c e s . F u a c t i o n a l l y ) t h e instrumeritation and c o n t r o l o f the chernical proce s s sampler i s similar t o t h a t provided on t h e fuel sampler-enricher system; however, t h e deta5.l. d e s i g n of the chemical p r c c e s s system sampler i s sirripkr. This r e d u c t i o n i n complexity r e s u l t e d from reduced r e q u i r e ments for containment, which, i n t u r n , resuLted from the lower r a d i a t i o n l e v e l s p r e s e n t i n t h e chernical processing system. The reduced c o n t a i n ment requirermxits permitted the use of conventional (single t r a c k e d ) c o n t r o l c i r c u i t r y i n s t e a d of t h e redundant (dual. t r a c k e d ) "sa-Sety grade " c i r c u i t r y used 5.n t h e f u e l sampler-enricher. Also, it vas p o s s i b l e , i n some c a s e s , t o use commercial-grade corn~ponentsi n s t e a d of s p e c i a l welds e a l e d components. I n o t h e r c a s e s t h e r e d u c t i o n i n r e q u i r e m m t s f o r containment and/or redundancy e l i m i n a t e d t h e rzeed f o r components.

Off-Gas Sampler

A system i s being designed to perinit a n a l y s i s of t h e r e a c t o r o f f -

The arrangement i s shown s c h e m a t i c a l l y on F%g. 2.13. A s i d e stream of LOO cc/min i s t a k e n from t h e r e a c t o r oTf-gas strean a t a, p o i n t downstream of t'ne i n - c e l l volume holdup. The sample stream p a s s e s to t h e sample u n i t i n l e t manifold, whence it may be r o u t e d t o one of t h r e e a l t e r n a t e p a t h s : gzzs stream.

1. a thermal c o n d u c t i v i t y c e l l f o r on-line d e t e r n 6 n a t i o n af g r o s s con-

t amimnt l e v e l ,

a chromatograph c e l l f o r batch-wise and q u a n t i t a t i v e deterraination

a r e f r i g e r a t e d molecular s i e v e trap f o r i s o l a t i o n of a concentrated sample, which will be t r a n s f e r r e d t o 2 h o t c e l l f o r analysis.

of contaminants,

The sample equipnent w i l l be homed i n a contairment box I-ocated i n t h e p i p e t r e n c h south of the vent house. A r e c i r c u l a t i n g a i r system coupled w i t h a r a d i a t i o n d e t e c t o r i s provided t o permit rapid d e t e c t i o n of system l e a k s .

I n a d d i t i o n t o Yne off-gas sampler, an attempt w i l l be mde t o study t h e n a t u r e and c h a r a c t e r OS o f f - g a s contaminants by i n s e r t i n g v a r i o u s sample coupons i n t o t'ne pwnp-bow1 vapor space through tile sampler-enrleher line. Instrumentation and c o n t r o l s d e s i g n Tor t h e o f f - g a s s a ~ ~ l is e r in p r o g r e s s and nearing completioii. I n s t r i m e n t a t i o n i s being provided f o r

68 ORNL-DNG 56-4756

I..........

RECIRCULATING AIR SYSTEM

I I I

.........

I I

TO AUXILIARY

......

.......

........... NOTE: DEI-AY TIME BETWEEN PurJJIp BOWL A N D SAMPLE UNIT APPROX 40 min

ENRICHER SAMPLER

SAMPLE-ISOLATION BOMBS

REFRIGERATED MOLECUCAR-SIEVE TRAP

L---..

SAMPLE TRANSFER BOTTLE

I J

1 0 0 ~ ~ ~ / ~ i ~ 3psiq

4200 crn3/rnin

.--.=:I-VOLUME HOLDUP FUEL PurdP BOWL

7----

.......... ..........

STACK

L I N E 522 REACTOR OFF-GAS

Fig. 2.13.

Schematic Uiagram

- MSRE

Off-Gas

Sampler.

on-line chromatographic and conductivity a n a l y s i s ; f o r measurements o f flows, p r e s s u r e s , and temperadtuxes r e q u i r e d f o r proper operation of and i n t e r p r e t a t i o n of data from t h e chromat,ograph and cond.uctivity analyzers; f o r c o n t r o l of temperature of a molecular s i e v e t r a p and- of t h e level- of a 1-iquid-nitrogen b a t h i n which t h e mol.ecula,r sieve i.s immersed; f o r det e c t i o n and annunciation of undesirable operating conditions; and t o prevent t h e occurrence of hazardous c o n d i t i o n s .

Since t h e sampler w i l l be an integral. p a r t of t h e primary containment during samplj.ng operations, and s i n c e some coniponents of t h e sampler would not meet t'ne requirements for primary containment system components, sol-enoid block valves w i l l be i n s t a l l e d i n t h e inl.et and- o u t l e t l i n e s which connect tine sanpl-er -Lot h e r e a c t o r system. Two valves w i l l be i n s t a l l e d i n s e r i e s i n each l i n e . These valves w i l l a u t o r m t i c a l l y c l o s e and i s o l a t e t h e sampler f r o m t h e r e a c t o r system i n t h e event of high pressu.re i n t h e r e a c t o r containment c e l l , high pressure i n -the fuel-pimp bowl, o r high a i r a c t i v i t y i n t h e smpl.eP enclosure. R-gh r e a c t o r c e l l p r e s s u r e i s i n d i c a t i v e of a r u p t u r e of t h e primary containment and t h e occurrence of t h e maximum c r e d i b l e a c c i d e n t . High fuel-pump-bow1 p r e s s u r e indicates t h a t conditions e x i s t t h a t c0ul.d. r e s u l - t in a r u p t u r e of t h e sampl.er p r i High sampler-air a c t i v i t y i n d i c a t e s t h a t a rupture QS mary contaimnent t h e sa,mpl.er pri-mary containment has occurred. Closure of t'ilt: hS.ock va,lves r e s u l t i n g from high sampler-air aci;ivi.t,y (and t h e accompanying alarm) w i l l a l s o provide p r o t e c t i o n t o t h e sampler opel-ator agains-l; t'ne occurrence of high 'oackgreound r a d i a t i o n r e s u l t i i l g from small l e a k s i n t h e sampler. Sampler-air a c t i v i t y w i l l be d e t e c t e d by Lwo GM-tube-type (OKNL model QJ.916) g m a monitors, which w i l l monitor two s e p a r a t e and independent

69 a i r samples c o l l e c t e d from and r e t u r n e d t o t h e sampler e n c l o s u r e . The i s o l a t i o n block v a l v e s and a s s o c i a t e d d e t e c t i n g instruments and c o n t r o l c i r c u i t r y were designed i n accordance w i t h t h e recommendations of t h e ORNL "Proposed Standard f o r t h e Design of Reliable Reactor P r o t e c t i v e Systems." A t least t w o independent devices were used t o supply i n p u t s i g n a l s t o t h e system and t o e f f e c t t h e c o r r e c t i v e blocking a c t i o n . One-out-of-two l o g i c w a s used i n t h e c o n t r o l c i r c u i t r y , and s e p a r a t i o n and i d e r i t i f i c a t i o n were maintained i n t h e d e t a i l d e s i g n of t h e w i r i n g a

Panel-mounted i n s t r u m e n t a t i o n w i l l occupy 5 l i n f t of p a n e l ( 6 f t high X 2 f t d e e p ) . These p a n e l s w i l l be l o c a t e d i n t h e vent house, south of t h e r e a c t o r b u i l d i n g . The sampler and a s s o c i a t e d i n s t r u m e n t a t i o n w i l l be l o c a t e d i n a .trench o u t s i d e t h e v e n t house. Since a11 major s m p l i n g o p e r a t i o n s w i l l be c a r r i e d o u t a t t h e sampler, a l l readoui; of information w i l l be p r e s e n t e d a t t h e sampler p a n e l s ; however, occurrence of an alarm c o n d i t i o n a t t h e sampler w i l l a c t u a t e an annunciator i n t h e main c o n t r o l room, and p r o v i s i o n s are being made t o pe-rmit some information t o be t r a n s m i t t e d t o t h e Computer-Data Logger. ALSO, a sample permissive s v i t c h w i l l be 1-ocated i n t h e main c o n t r o l room. T h i s switch, which i s connected i n t h e block valve c i r c u i t s , w i l l be used t o prevent o p e r a t i o n of t h e sampler without knowledge of t h e r e a c t o r o p e r a t o r s . Most of t l e instrument components used i n t h e o f f - g a s sampler were sa.lvaged. from t h e ORNL PIT%-47-45 experiment Located a t IrWno Falls or were on. hand i n ORNL Xeactor D i v i s i o n s t o r e s . Reconditioning a i d c a l i b r a t i o n of t h i s equipment and procurement of a d d i t i o n a l components are nearing completion. P r e p a r a t i o n of instrument a y p l i c a t i o n drawing i s e s s e n t i a l l y Intercomection complete. Panel design i s approximately 75$ complete w i r i n g and p i p i n g design i s under way, and f a b r i c a t i o n or" panels I s also under way.

Xenon Migration i n t h e MSB3 Based on r e s u l t s of t h e 85Kr ex-p'eriment2 and xenon s t r i p p e r e f f i ci.ency r e p o r t e d by t h e U n i v e r s i t y of Tennessee, t h e s t e a d y - s t a k e 135Xe poison f r a c t i o n f o r t h e MSRE w a s computed.. The following major assumpt i o n s were made: I-.

Jo bubbl.es c i r c u l a t i n g w i t h t h e f u e l s a l t .

Iodine remains i n s o l u t i o n , t h a t is, it i s not adsorbed on any surf a c e s and i s not v o l a t i l i z e d i n any form.

Xenon i s not 'adsorbed on any s u r f a c e s .

mass t r a n s f e r of xenon a c r o s s t h e s a l t - g a s i n t e r f a c e i n t h e graphi t e pores w i l l not be i n t e r f e r e d with, f o r example, by t h e accum-cilat i o n of sludge or f i s s i o n products a t t h i s i n t e r f a c e . The

70 To compute t h e 135Xe poison fracLion, t h e 135Xe concentration i n t h e s a l t must fi.rst be calcu.l.ated. This i s acconiplished by t h e fol-lowing r a t e bal.ance : " 5 ~ e generation r a t e = ' 3 5 ~ e decay r a t e i n sa2.t -i- 135Xe

where

burnup r a t e i n s a l t

1-35Xe s t r i p p i n g r a t e

(1.1

+ 1 3 5 ~ emigration r a t e to g r a p h i t e ,

135Xe migra,ti.on raLe t o g r a p h i t e = "' Xe

burnup r a t e i n g r a p h i t e

135Xe

decay r a t e i:n g r a p h i t e . ( 2 )

.kt a gi-ven power l e v e l tlie l e f t s i d e of Eg. (1) i s a c o n s t a n t , and tine r i g h t s i d e i s a f u n c t i o n of t h e "'Xe concentration i n t h e s a l t . A f t e r t h e concentration i s computed t h e 135Xe poison f r a c t i o n may t h e n be computed, 'The r e s u l t s of this calcul-ation a t eqv.il.ibrium a r e shown i n F i g s . 2.14a, b, and e , as a f u n c t i o n of t h e variab1.e Tndicated when all. o t h e r va,riables remain c o n s t a n t . Yne c i r c l e on t h e curve i n d i c a t e s t h e ex.pected. or design v a 1 - i ~ . For t h i s c a l c u l a t i o n t h e core was divided i n t o 72 regions, and- average f l u x e s and a d j o i n t f l u x e s were used f o r each region. Figure 2.14~shows t'nat t h e poison f r a c t i o n i s c o n s i d e r a b l lower a t low power l e v e l s . This i s because a higher f r a c t i o n of 13%e decays a t t h e s e power l e v e l s . One notable r e s u l t of t h e c a l c u l a t i o n i s t h a t t h e xenon poison f r a c t i o n d i d not chan e i n value when t h e d i f f u X lo-+ f-t2/iir. This a i v i t y of xenon i n g r a p h i t e ranged from lO-"-Lo.5 i s because t h e mass t r a n s f e r c o e f f i c i e n t from s a l t 'to g r a p h i t e i s cont r o l l i n g t h e t r a n s f e r process. 'Ynerefore, i f futuye r e a c t o r s have low iiiass t r a n s f e r coefficieil-Ls as i n t h e PGRE, it m y not be necessary t o purchase t h e more expensive low-void-fraction and l o w - d i f f u s i o n - c o e f f i c i e n t g r a p h i t e , i f 135Xc poison f r a c t i o n j.s t h e only c o n s i d e r a t i o n . The finalmeasured 135Xe poison f r a c t i o n may be d i f f e r e n t from t h e s e predi.cted values '0-cause of t h e asswnpt5.ons involved. As more information i s gained about t h e r e a c t o r system and i t s chemistry, t h e eqimtions w i l l be a d j u s t e d t o provide a b e t t e r model f o r c a l c u l a t i o n of t h e migration i n f u t u r e sys'wiiis. b

Rem0te &Taintenanc e The a c t i v i t i e s o f t h e remote maintenance group were d.ri.ctated 1argel.y by t h e condition of t h e r e a c t o r . Dixing t h e l a s t s t a g e s of c o n s t r u c t i o n and f o r as 1on.g as t h e c e l l w a s open, a t t e n t i o n w a s given t o t r y i n g t h e remote maintenance techniques om t h e instal-led. equipment and I n checki n g t o ensure and improve maintaina'oility. Once t h e eel-1s were c l o s e d t h e e f f o r t w a s tilrned t o recording experiences and pl.arming f o r l a t e r work. T.,a,tcr, a c t u a l maintenance w a s performed i n . s e v e r a l a r e a s . A des c r i p t i o n of 'ihis work i s given below.

71 ORNL-DWG 66-4757

STRIPPING

0.02

E F F I C I E N C Y (70)

0.06

0.04

MASS-TRANSFER

0.08

0.to

C O E F F I C I E N T T O BULK G R A P H I T E (ft/hr)

i REACTOR

POWER

(Mw)LOG

’1 00 SCALE

(a) E f f e c t of S t r i p p i n g E f f i c i e n c y on 135Xe Poison Fig;. 2.14. Fraction; (b) Effect of Mass Trausfer C o e f f i c i e n t (311 I3’Xe Poison Erac.f;ions; ( c ) E f f e c t of Reactor Power on 135Xe Poison F r a c t i o n .

'I 2 P r a c t i c e Before Operation P r a c t i c e w i t h r e a c t o r components .was had i n handling .the pump TO-= t a r y element and i n changing t'ne existj-ng g r a p h i t e sample assemb1.y f o r t h e f i n a l untt Tne s m p l i n g procedime included .tile ha.n.d.l..ing and/or operation of (1)an i n e r t atmosphere i n t h e standpipe, ( 2 ) a specialh e a t e r tool- t o thaw out a f r o z e n s a l t annulus around -the outside of t h e s a - q l e holddown assembly, ( 3 ) disconnects, valves and f l a n g e s i n s i d e t h e standpipe, ( 4 ) stowing t h e holddown assembly, and (5) t h e sample its e l f . I n a d d i t i o n t o t h e s e a l i m i t e d visilal i n s p e c t i o n of the core w a s conducted u.sing a ? / % i n . -diam scope A speci-al. f i t t i n g had t o be i n s t a l l e d I n tile s t r a i n e r basket above t h e core t o aceonmodate t h e r e v i s e d sample assembly.

The pump rotai-y element wads l i f t e d out of -the c e l l for i n s p e c t i o n using t h e l i - f t i n g yoke and crane w i t h i n - c e l l d i r e c t guiding. 13uring t h e L i f t , c l e a r a n c e s of a l l t h e a u x i l i a r y equipment; were observed and p o i n t s Where damaging i n t e r f e r e n c e s could- occur were noted. The u n i t w a s r e i n s t a l l e d by remote means u s i n g ,the view aPfoided through t h e p o r t a b l e maintenance s h i e l d . T'ne process of torqueing up t h e twenty-two 11/2-in.-diam b o l t s in t h e pimp's lower i'lange was s t a r t e d i n t h e p o r t a b l e s h i e l d b u t was f i n i s h e d w i t h d i r e c t means t o save t i m e i n t h e :reassembly p r o c e s s , Wlnile s e t q i n this a r e a , r e p r e s e n t a t i v e e l . e c t r i c a 1 and ther.mocouple disconnects, pump-bowl h e a t e r s , and auxil-iary flanges were hand l e d w i t h t h e long-handled- t o o l s . Proced.ures were r e v i s e d , and i n cases l i k e t h e pump, g r a p h i t e samp l i n g , and t h e control. rods were w r i t t e n up i n minute detail.. Tc2bulat i o n s were prepared r e l a t i n g h e a t e r s thermocouples spare discomtects, Add.itiona1 and o t h e r equipment w i t h shield-block l o c a t t o n s a m i el.evations t o o l s were designed, and. some e x i s t i n g t o o l s were r e v i s e d .

Maintenance of Radioactive Systems

_ _ I I

I n January, a f t e r a s h o r t p e r i o d of power operation, it was necessary TahI.e 2.1 shows t h e op-e r a t i o n s which were done *and. t h e a c t u a l time and inanpower used.. Radiatlon l e v e l s were s i g n i f i c a n t l y lower t h a n t h o s e which are a n t i c i p a t e d a f t e r prolonged power operation While t h i s r e q u i r e d only minimal. shiel.ding, enough of t h e s h i e l d i n g was used for t h e operations w i t h the c o n t r o l rod and. PCV 522 t o prwvide experience i n s e b t i n g up and i n using t h e t o o l s through t h e p o r t a b l e s h i e l d i n g . Although PCV 52% and i-ts f i l t e r assembly was q u i t e a l a r g e r a d i o a c t i v e sou-rce, 100 r / h r a t t h e o u t e r surface o f t h e f i l t e r , no s i g n i f i c a n t personnel exposure w a s eacomtei-ed. I n g e n e r s l t h e t o o l s , Lechniques and previously made prepara1;ions proved more t h a n adequate. In some cases it w a s necessary t o f a b r i c a t e s p e c i a l t o o l s o r r e v i s e existkng ones, b u t 'tiiiese cases & i d not h o l d up progress t o any Good cooperation b e b e e n management r e a c t o r operations, grea2; e x t c n t maAntenance planning, I-ieal-th physics, and t h e c r a f t f o r c e s comtri.buted toward e f f i c i e n t and smoothly rim o p e r a t i o n s .

to use remote maintenance on a number of t a s k s . a

Be scription

Rigger and Operat o r

Nillwright

Pipe F i t t e r

-hemote

kintenanze

,,,e

hir)

Date

~~~~

1. Remove check valve fro:::

l i n e 533 (use ~ani-loc on e x t e n s i m )

Xencxre FE 521 arti replace with a new u n i t

Control rod drive Xo. 3 : remove shielding, discoriiects, an& cover plate

Control rod drive Xo. 3 : remve drive and i n s t a l l nev &rive

1 2

;an. 2E:

Jan. 29

Jar:. 31

Control r o d drive No. 3 : hook up a i r and e l e c t r i c a l disconnects

Peb. 1

Fe-b. 2

PCV 522, unsuccessful attempt i n - c e l l

Feb. 3

PCV 522, remove an& put i n t o decontmi-

Feb. 5

â&#x201A;Ź'CV 522, reh,uild arid replace i n system K V 522, reiiime from systeci

Fe'b. 7

2-i/'2

~ e b .i:

Control rod drive Xo. 3: replace c m e r and s h i e l d replacerzent

nation c e l l

.''2 ,

13cV 522,, a t t a c 3 fi.wges for flow t e s t s

Feb. 9 and 13

KV 522, i n s t a l l nev assezbly

Feb. 10

4.6

6. PC'J 522, c ~ & f i l t e r lmse f r o n iralve, put i n can arid carrier

10.

i o t a 1 fhr)

4.4

76.5

Feb. 9

Molten-Salt Pump Opera-Lion i n t h e Prototype ._...__IPump Test-F a c i l i - i y . ~

The

modifications3 Lo t h e tesL 1 . 0 0 ~were compl-eted. The v e n t - m i flowifleLer w a s relocated upstream of Lhe o r i f i c e flow r e s t r i c t i . o n , and- a new f l . 0 ~ ~ s t r a i g h t e n i n g section was i n s t a l l e d near Lhe pump discharge. The nzw flow s t r a i g h t e n e r w a s modified bo provide ad-ditional. w e l d attachment of the blades inside t h e pi-pe. The new arrangement of -Lhe system i s showrl i n F i g . 2.1.5.

I'wo test runs were made w i t h the prototype pump c i r c u l a t i n g t h e salt; T , i F - B e F z - Z r ~ / + - T h ~ ~ ~ - U(6€4.4-24,6-5 Fq .O-1.1-0.9m o l e %) a t 1200°F. Ti1.e

ORNL-DWG 66-2048

FEET

AIR THERMAL WIILL-. I I

VENTURI METER

-------I N L E T PRESSURE -8-in.

PIPE

,6 - i n _----

~~~

PIPC SALT FLOW -FREEZE VALVE

FLANGE

--"::F i g . 2.15.

MSKF,

Sa1.t Pump Xot Test Facility, Modified.

75 f i r s t run covered a p e r i o d of 165 h r t o provide hot shakedown of t h e i m p e l l e r (13-in.-OD) f o r t h e f u e l pump s p a r e r o t a r y element. The o t h e r run covered a p e r i o d of 166 h r t o provide shakedown of t h e d r i v e motor f o r t h e s p a r e coolarit pump. The p r o t o t y p e pmp i s being prepared for t e s t w i t h a n l l - L / 2 - i n . i m p e l l e r . Measurements w i l l b e made w i t h t h e r a d i a t i o n densitometer t o determine t h e undissolved gas content of t h e c i r c u l a t i n g s a l t . Other t e s t s w i l l be made i n t h e pwnp t a n k o f f - g a s c i r c u i t i n connection w i t h t h e plugging i n c i d e n t s experienced a t t h e MSlU.

Pmp Rotary Element Modification. The s p a r e r o t a r y element for t h e f u e l s a l t pump w a s modified t o provide a p o s i t i v e seal a g a i n s t leakage of o i l from t h e c a t c h b a s i n p a s t t h e o u t s i d e of t h e shield- plug =and i n t o t h e pump t a n k . Previously, a solid copyer O-ring compressed between t h e b e a r i n g housing and s h i e l d plug w a s used t o provide t h e s e a l . I n c i d e n t s ?lave occurred wherein o i l leaked p a s t t h e O-ring. C r o s s - s e c t i o n a l views of t h e p a r t of the pump which i n c l u d e s t h e modifications a r e ahova i n F'i.g. 2.1-6. The l a r g e r s e c t i o n shows t h e r e l a t i o n s h i p s between the pmp shaft, t h e shaft lower s e a l , bearing housing, c a t c h b a s i n , s h i e l d plug, and t h e pump t a n k . 'The exploded views i n d i c a t e t h e n a t m e of t h e m o d i f i c a t i o n . P o s i t i v e containment of t h e o i l i s obtained by providing a s e a l weld between t h e b e a r i n g housing and t h e s k i e l d p l u g . The r o t a r y element i s being assembled for cold shakedown, and aI"ter s a t i s f a c t o r y o p e r a t i o n w i l l be p r e p a r e d for MSRE: use and s t o r e d . TIie s p a r e r o t a r y elemerit f o r t h e c o o l a n t pwnp w i l l r e c e i v e t h e same modifica-Lion. L u b r i c a t i o n System. Modified J e t pwnps': were i n s t a l l e d i n t h e r e t u r n o i l l i n e s of t h e MSEE salt pump l u b r i c a t i o n s y s t e m s . The Lubrication pump endurance t e s t 5 was continued, and t h e pmp has now operated continuously f o r 22,622 h r c i r c u l a t i n g o i l a t 1GO"F and 70 gpm.

MI(-2 F u e l Pump. reviewed.

The pump t a n k d e s i g n w a s completed, and it i s being

Drive Motors. A new d e s i g n was completed f o r t h e c o n t a i m e n t v e s s e l f o r the d r i v e motors of t h e PISm s a l t purrps. It provides single containment â&#x201A;Źor t h e e l e c t r i c a l power p e n e t r a t i o n s , i n c o n t r a s t t o t h e double conta,inment provided in t h e o r i g i n a l design. The r e s u l t i r i g s i m p l i f i c a t i o n should e l i m i n a t e a s e r i o u s f a b r i c a t i o n probl-em p r e v i o u s l y experienced w i t h weld-induced 1 . m i n a t i o n s i n the v e s s e l wa.11. Other Molten-Salt Pwnps

PK-P F u e l Pump Bigh-Temperature Endurance T e s t . Endurance operation6 of t h i s pump w a s continued, and it has now operated continuously f o r 5160 hr c i r c r d s t i n g t h e s a l t LiE'-BeF2-ThFg-W4 (65-30-4-1 mole $) a t 120Q0F, 800 gpm, and 1650 rpm.

76 Pump Containing a Molteil-Salt -Lubricated J o w n a l Bearing. --..

This

was p l a c e d i n o p e r a t i o n circu1.atin.g s a l t a t 1200째11',but; it ex-p1mp79 peri-enced a s e i z u r e af.i;er 1 h r of op2ra-ilion. Examination revealed the s e i z u r e to be in t h e m o l t e n - s a l t - l u b r i c a t e d b e a r i n g . A s w a s -Lhe case w i . t h the t e s t previous to t h i s one,5 two of - t h e snap i-i.ngs t o r t h e b e a r ing s l e e v e gimbals support were l o s t and tlne o t h e r t w o were o n l y 1.aosel.y retaj-ned. Whether t h e b e a r i n g s e i z u r e o r l o s s of t h e snap r i n g s occurred first j.s a moot q u e s t i o n . The design of t h e gimbals s u p p o r t i s being J

BUNA N O-RING

SOLID COPPER O - R I N G

. ,

LOWER SEA!. CATCH BASIN

B E FOR F M 0D IF IC AT ION

O R N L - D W G 66-2049

LOWER S E A L CATCH BASIN

AFTER 2nODIFICAi.ll)N

S H I E L D PI-UG'

F i g . 2.1.6. MSIIF: S a l t Pump Rotary Elemeni;, Modification.

77 modified t o e l i m i n a t e t h e use of t h e snap rings, which are intended f o r r e t a i n i n g t h e f o u r fulcrum p i n s i n t h e support. I n s t e a d , t h e p i n s w i l l be r e t a i n e d by plugs tack-welded a t t h e i r o u t e r ends. Instrument Development U l t r a s o n i c Single-Point Molten-Salt Level Probe A s no f u e l has been processed during t h e l a s t r e p o r t period, t h e ultrrssonic l e v e l probe i n s t a l l e d i n t h e MSRE f u e l s t o r a g e tankLohas not been used.

E f f o r t s t o c o r r e c t t h i s i n s t r u m e n t ' s d e f i c i e n c i e s have been wsuccessful.. The e x c i t a t i o n o s c i l l a t o r which had proved s o u n s t a b l e w a s modified c o n s i d e r a b l y (using i r i f o m a t i o n s u p p l i e d by t h e manufacturer) i n an attempt t o e l i m i n a t e i t s excessive frequency d r i f t . T'nese modif i c a t i o n s made no improvement i n t h e s t a b i l i t y of t h e asci-l-lator. As t h e d e s i g n and success of o t h e r intended modifications depended upon t h e s t a b i l i t y of t h i s component, none of them have been attempted. To c o r r e c t t h i s s i t u a t i o n , t h e ORNL Instrumentation and Controls Division Elect r o n i c Design Group has been requested t o i n v e s t i g a t e t h e e l e c t r o n i c equipment a s s o c i a t e d w i t h t h e instrument and make recommendations a s t o t h e most p r a c t i c a l a c t i o n t o t a k e . High-Temperature NaK-Filled D i f f e r e n t i a l - P r e s s u r e T r a n s m i t t e r The c o o l a n t - s a l t system f l o v t r a n s m i t t e r t h a t f a i l e d i n s e r v i c e a t

-Lhe J J ' I S R . Z " * ~ w ~~ a s~ ~r e f i l l e d w i t h s i l i c o n e o i l and t e s t e d wLth t h e

seals

a t room temperature. P r i o r t o r e f i l l i n g t h e t r a n s m i t t e r body, a vacuum pump w a s connected t o t h e instrument i n such a lilanner t h a t t h e p r e s s u r e could be reduced on t h e process s i d e of b o t h seals and both s i d e s of t h e s i l i c o n e - f i l l e d body a t t h e same -time. Liquid traps were i n s t a l l e d i n t h e body e v a c m t i o n l i n e s t o c a t c h any o i l t h a t might be f o r c e d out of t h e t r a n s m i t t e r body by t h e expansion of t r a p p e d gas during evacuation. When t h e p r e s s u r e was reduced to 28 i n . EEg vacuum ( t h e lowest p r e s s u r e a t t a i n a b l e w i t h t h e system a t t h a t t i m e ) , o i l w a s f o r c e d froi-n t h e c a p i l l a r i e s : 8.2 ml froin t h e low-pressure s i d e of t h e t r a n s m i t t e r , and 15.8 m l from t h e high-pressure s i d e . This i n & i c a t e s t h a t t h e r e w a s gas t r a p p e d i n b o t h s i d e s of t h e t r a n s m i t t e r body, and t h a t t h e amounts trapped were unequal. 'Tile exac-t amount of gas t r a s p e d cLsrinot be c a l c u l a t e d from t h e arnouits of o i l caught i n t h e contaLners, because the c a p i l l a r i e s a r e not c o m e c t e d t o t h e two sides of the t r a n s m i t t e r body i n t h e ~itiiieh o r i z o n t a l p l a n e . A f t e r it w a s r e f i l l e d , t h e temperature s e n s i t i v i t y of t h e i n s t r u ment was 1 i n . (water c o l m ) change i n i n d i c a t e d output, f o r each degree Fahrenheit change i n ambient t e r n p e r a t w e . This s e n s i t i v i t y i s g r e a t l y reduced from t h a t observed p r i o r t o r e f i l l i n g but i s s t i l l e x c e s s i v e .

AL1 t h e above t e s t i n g was done w i t h t h e s e a l s and t r a n s m i t t e r body at room temperature. The s e a l s a r e now being heated. t o 1.200째F, a t which temperature t h e t e s t w i l l be continued.

78 The new NaK-filled d i f ~ e r e n t i a l - p r e s s u r et r a n s m i t t e r ordered as a. spare f o r t h e MSRE i s scheduled f o r d e l i v e r y i n .March. Float-'Yme Molten-Salt Level 'i'ransinitter Perf orrnance of khe bal.l.-fI..oat-type t r a n s n ~ t t e ri n s t a l l e d on t h e MSRE coolant-sal?, pu~fi,p'~continues .Lo be satj.sf3.ctory. The necessary a c t i o n s have 'oeen completed t o c o r r e c t t h e previously reported errors i n cal.lbra-Lion. 1 4 l5 A s t,hese were c a l c u l a t e d correct<.ons, some a d d i t i o n a l f u t u r e sdju.stment may be r e q u i r e d . The b a l l - f l o a t l e v e l t r a n s m i t t e r or1 -the MSm p u m p t e s t loop contiiuies t o operate s a t i s f a c t o r i l y , although on one f i l l -the f l o a t woul..d. not r i s e u n t i l t h e temperature of t h e h e a t e r on tine bottom of t h e f l o a t chamber was increased. E i t h e r u:nmel.ted s a l t o r curvatixre of t h e bottom i n s i d e t h e f l o a t chamber may now be assumed. t o be t h e cause of t h i s sticki n g . A previous i n s p e c t i o n of t h e core tube showed no d e p o s i t s t h a t would cause it t o s t i c k i n t h e core chamber. The bottom i n s i d e curvature of t h e f l o a t chamber 011 t h e I%RF pump t e s t loop f i t s the curved bottom of t h e f l o a t very w e l l and may block t h e entrance o f t h e molten s a l t i n t o t h e c h a i f k r . This design e r r o r -was noted p r i o r t o t h e f a b r i c a t i o n of %he f l o a t chamber f o r t h e MSFE aiid c o r r e c t e d on t h e a s s w q t j . o n t h a t t h i s valving a c t i o n might occur. The bottom of t h e f l o a t chamber vas f l a t - . 'cened s o thaJt t h e round-bottom float; could i m t block -the flow of the molten s a l t i n t o the chamber Except f o r d e t a i l i n g of the d i f f e r e n t i a l transformer assembly, d2s i g n of t h e b a l l - f l o a t , t r a n s m i t t e r i n s t a l l a t i o n in t h e MK-2 M S R E fuel. c i r e u l a , t iiig purrrp has b e en c onip1e.i;e de

One of t h e prototype bal-1-float l e v e l t r a n m i t - t e r s l 6 i n s t a l l e d on t h e l e v e l t e s t loop completed f o u r years of operation a t temperature t h i s month. It i.s s t i l l . operating s a t i s f a c t o r i l y . The o t h e r was r e moved l a s t year s o t h e ultrasoni.c s i n g l e - p o i n t l e v e l i n d i c a t o r cou.l.d. be i n s t a l l e d . It w a s operating s a t i s f a c t o r i l y when removed I

Conductivity-Type Single-Point Molten-Salt Level ?robe .._ Performance of t h e conductivity-type l e v e l probes I.nstalLed i n t h e

MSRE f u e l , f l u s h , and coolant d r a i n tanks continues to be s a t i s f a c t o r y . 'There have been no f u r t h e r f a i l u r e s of e:citation and. s i g n a l c a b l e s on t h e s e probes.

Single-Point Termeratme A l a r m Switches Observation of t h e performance of 1-1-0 s i n g l e - p o i n t temperature alarm switches i n s t a l l e d a t t h e MSRF: has continued. As r e p o r t e d pre-vic11.j.sI.y~~ t h e switch modules were r e s e t p r i o r t o power operation of -the r e a c t o y . Data obtained from subsequeiit spot checks o f module s e t p o i n t s i n d i c a t e d

79 tha.t a few modules had s h i f t e d e x c e s s i v e l y ; however, t h e s e d a t a are coris i d e r e d t o be i n c o n c l u s i v e because r e c o r d s i n d i c a t e d t h a t t h e modules m ~ y have been r e a d j u s t e d . Some a d d i t i o n a l c a s e s of d u a l s e t p o i n t s wexe d i s covered and c o r r e c t e d . Routine checks and observations of modde p e r f o r mance w i l l be continued until s u f ' f i c i e n t d a t a are obtained t o permit a n a c c u r a t e e v a l u a t i o n of t h e r e l i a b i l i t y of t h e s e d e v i c e s . Helium Control Val-va T r i m Replacement T e s t i n g of alternate m a t e r i a l corribirmtions f o r helirun c o n t r o l valve t r i m has been t e r m i n a t e d . Since t e s t s had shown t h a t a l l t h e a l t e r n a t e materiaL combinations under c o n s i d e r a t i o n would gall when o p e r a t e d i n d r y helium without l u b r i c a t i o n and t h a t none would g a l l i f a minute amount of l u b r i c a n t w a s p r e s e n t , 1 7 t h e v a l v e s which had f a i l e d i n MSRE s e r v i c e were r e f i t t e d w i t h spare t r i m using t h e o r i g i n a l (17-4 PH plug and S t e l l i t e iTo. 6 ) material combination. Close a t t e n t i o n was given t o alignment during reassembly o f t h e v a l v e s , and a l l t r i m w a s given a, l i g h t c o a t of

machine o i l b e f o r e i n s t a l l a t i o r i . A l l t h e r e p a i r e d valves operated satisf a c t o r i l y j n shop t e s t s . One of t h e r e p a i r e d vaLves was iiistalLed i n t h e MSRE main helium supply l i n e and operated f o r s e v e r a l months b e f o r e s t i c k i n g . One addLtiona1 helium c o n t r o l valve fail-ure (also due t o s t i c k i n g ) has occurred. Both v a l v e s are being disassembl-ed and w i l l be r e f i t t e d w i t h s p a r e (17-4 PH t o S t e l l i t e 80. 6 ) t r i m . Because tine f a i l u r e s may be due t o evaporation of t h e l u b r i c a n t , a n attempt w i l l be made to f i n d a l e s s v o l a t i l e o i l o r g r e a s e t o use f o r t r i m l u b r i c a n t . Previous a t tempts t o use graphi t e - b a s e l u b r i c a n t s were not s u c c e s s f u l . Thermocouple Development arid T e s t i n g

Coolant S a l t Radiator D i f f e r e n t i a l Temperature 'Tnerniocouples Noise i n t h e c o o l a n t s a l t r a d i a t o r d i f f e r e n t i a l temperature thermocouple c i r c u i t which was under i n v e s t i g a t i o n " was f i n a l l y reduced t o an a c c e p t a b l e l e v e l . A f i n a l check on t h e e f f e e k s of themnocouple and lead-wire material mismatch was made by hea-Ling t h e i r disconnects b o t h i n d i v i d u a l l y arid s i r n u l taneousljr to L50'F. No readable change i n t h e output voltage was noted. A seven-point c a l i b r a t i o n was run on t h e thermocouple p a i r between 1040 and 1250째F, which resulted- i n a c o n s t a n t e r r o r w i t h t h e o u t l e t t h e m o couple reading 0.220 IKV high with r e s p e c t t o t h e i n l e t thennoco'uple . The r e s i s t a n c e of t h e thermocouple 2 . 0 0 ~ was determined t o be high ellough -to r e q u i r e r e c a l i b r a t i o n of t h e r e c e i v i n g instrumerit -toIr1aintai.n r e q u i r e d accuracy. Also, tine zero of this instrwnent was o f f s e t t o c o r r e c t f o r t h e thermocouple loop e r r o r . 'Thermocouple D r i f t Tests. The checking of e i g h t rnetaL-sliea,thed m.inera1-insulated ChromeL-Alumel themlocouples f a b r i c a t e d from 1GF.E mat e r i a l for c a l i b r a t i o n (2rift; a t 1250'F' w a s concluded.19 All themocouples continued t o show some d r i f t to t h e end of a 26-month t e s t p e r i o d . The f i n a l temperature e q u i v a l e n t d r i f t values w e r e between 4 7 mid +6.4'F. a

80 Temperature Scanner

_l-._l

Perforimnce of %he temperature scanning system devel-oped f o r use a t t h e MSRE2 has conti-nued- t o be s a t i s f a c t o r y . The modification p r e v i ou;sI..y~reported., 21 together wi.th Tmproved. tal-ibration and maintenance procedures, appears t o have eliminabed t h e c a l i b r a t i o n ~ i f problems. t Perfo-m;nce of t h e mercury switches has been exce1.l.ent. We 'rrad expected. t h a t t h e swi-Lches w o u l d need- frequent a'ilention and tha-t %l?e mean l i f e between r o u t i n e cleaning o r repair would be about 1000 hr. The switches have given very 1 i t L l e t r o u b l e , and -the mean l i f e of the switzlies has been much g:l'ea-i;er t h a n 1000 h r . Since t h e start of o p e r a t i o n of t h i s system i n September 1964, t h e r e have been no bearing o r o t h e r mechanical f a i l u r e s of t h e five switches instaL1.rd. Four switches developed excessive noise dul-ing t h i s p e r i o d and requirec? cleaning and. replacement of the mercury. In one of t h e s e cases t h e switch f a i l u r e was caused by a f a i l u r e i n Lhe n i t r o g e n purge gas supply system. -4l.l five switches were cleaned and reconclitioned. b e f o r e Lhe s t a r t of power operations as a routine precautionary nieasure .

References 1. -MSR Frogr-am Semi-aim. Progr. Rept. Aug. 31, 1.965, ORNL-3872,

35-58.

ibid., -

p. 55

MSR Program Semiarm. Progr. - :lcpt. A u g . 31, 1.965, ORI'JL-3872, p . 61,

-i b i d . . , p .

Ilia",

61.

p . 62.

6. I b i d . , p . 65.

pp.

MSii Program Semiann. Progr .....

Rept

July .3l, 1963, ORNTA-3529, p , 54.

_ I I _ _ _ _

8. 9. Y i R Program Semiann. P r o g r . Rept. Feb. 28, 1965, OKPdL-3812, p . 52. 10. MSK Program Semiarm. Progr. Rept. Aug.. 31, 1.965, ORNJ,-.3872, I _

11*

I b i d . , p . 70.

. Feb. Prop. . . Rept . Jan

12. -MSR Prograui Serniann. Progr. Rept .-._.I.Seuiri.aan. 13. MSR Program

14.

p . 66.

28, 1965, OEWL-3812, p . 48. 33,

.__.I+

-. MSI? ....- Program Semiann. ~ . . P . r o p . Repl;. A w . 31.,

1.963, ORNL-34l9, p. 45. 1965, 0KIu.TA-387%,p . 71.

15. MSR Program Seraiann. P r o g r . Rept. Feb. 28, 1965, QWL-3t3l.2, p , 4 l . 16. MSi Program Semiam. Progr. Rept. Feb. 28, 1962, ORNL-3282, p . 61. 1'7.

PER Frogram S e m i a m . P r o g r . Reppt. A%.

31, 1.965, OP3NL-3872, p. 7 2 .

18. I b i d . , pp. '73, ?A. _ I _

19. Ibid., p. 73. 20.

MSR Program Semiami. I r o g r . Rept

21. MSR Program Semiann. Progr

. A%.

31, 1962, 0X:NIL,-3.3O9, p. 71,

. Rept . Feb . 28,

1965, ORNL-381.2, pp. 4-4-45

MSRE REACTOR AnrAINSIS

Yoriiiula f o r Control Rod R e a c t ....... i v i_t.y.-Least-Squares ..-.-.-

One r o u t i n e f u n c t i o n of t h e MSIU d a t a logger w i 1 . 1 be t h e periodic: c a l c u l a t i o n of t h e s e p a r a t e r e a c t i v i t y e f f e c t s a s s o c i a t e d wi'ch r e a c t o r o p e r a t i o n above some base l i n e , o r z e r o - r e a c t i v i t y c o n d i t i o n . For t h i s pur-pose, one of t h e q u a n t i t i e s t h e computer must, c a l c u l a t e i s the nega... t i v e r e a c - i i v i t y cori-espond.ing t o each c o n f i g u r a t i o n oi" t h e s h i m and regul-ating r o d s . By use of a 1eas-L-squ.ares cixrve-fitting procedure, we have ob.tsined a n aiialytri e a 1 formula which c1osel.y approxri.rii.ates t h e i n t e g r a l curves determined fieom rod c a l i b r a t i o n experiments a t z e r o power. The functional. expression used f o r f i t t i n g the experimental curves w a s determined by applying a p e r t u r b a t i o n technique t o t h e i n t e g r a l exp r e s s i o n f o r t h e rod reac.'i,?.yi.ty, as o u t l i n e d below. If a r e f e r e n c e st;ate is chosen t o correspond Lo 7,:i:ro :rod j.n.sei-tion, an expression f o r t h e s t a , t i c r e a c t i v i t y change whm a s i n g l e r o d ( o r rod groiip) is i n s e r t e d t o a posi-Lion Z i i i a core w i t h e f f e c t i v e h e i g h t B and radius R i s

I n t h i s Porrnul-a, CP i s t h e colwnn vectois,of group fluxes corresponding t o t h e c o n d i t i o n w i t h %lie rods i n s e r t e d , Qo i s t h e row v-ec-tor of adjo?.!!t fluxes f o r t h e r e f e r c n c e s t a t e , 6A i s tiie l.oca1. p e r t u r b a t i o n i n t h e neut r o n removal. o p e r a t o r due t o absorptions i n t h e rods, and P i s t h e neut r o n production opera'coi-. T h i s expression can a l s o b e appI.ri.ecri i f t h e sh.im and. r e g u l a t i n g rods are inser-Led t o d i f f e r e n t p o s i t i o n s . To sS.rlipliJ'y t h e a n a l y s i s , we have assumed t h a t t h e t i p s of t h e shirr rods are a t equal i n s e r t i o n s , Z1, which i s a.lways equal t o o r .above ....-.. .. t h e position of t h e i:egl:7nl a t i n g rod, Z2. We f u r t h e r s p e c i a l i z e tiie formu1.a t o two-group d i f r u s i o n theory and one dimension, correspoinding t o t h e d i r e c t i o n of rod i-nsertior;. Equation (1)becomes

where s u b s c r i p i s 1 a n d 2 designa1,e the f a s t and thermal groups respPc:-

The qiiantity S Z(') i s t h e e f f e c i i v e increment i n thermal aba2 s o r p t i o n c r o s s s e c t i o n i n t h e region 0 5 z 5 Z1, poiso(.-d by t h e com'oined

tively.

83 s h i m and regulati-ng rod group, and 6ZL;) is t h e corresponding increment

i n Z1 5 z 5 Z 2 , poisoned. by t h e r e g u l a t i n g rod alone.

I n -the ixmal. approximation of p e r t u r b a t i o n theory, -Lhe f l u x distributio n s $1 (z) and @2 ( 2 ) a r e repli2ced by t h e unperturbed fluxes @i)l ( z ) and S o % (z), corresponding t o t h e r e f e r e n c e s t a t e . 1.S t h e appi-oxiimLions

are introduced i n t o ( 2 ) and the i n t e g r a t i o n s performed, the u s u a l formula for. t h e r e a c t i v i t y - v o r t h curve f o r a p a r t i a l l y i n s e r t e d c o n t r o l rod i s ' T h i s r e s u l t was t e s t e d by a d J u s t i n g t h e parameters 6C and. obtained.' a.2 82:,(2) i n order- t o f i t t h e f o r m l a t o t h e rod-worth curves obtained from

a2 experiment. bfiizile reasonably good agreement w a s obtained in f i t t i n g t h e cu.rve f o r t h e s i n g l e ( r e g a l a t i n g ) rod, poorer r e s u l t s wert? obtained. when com?iiaations of irrsertions of s h i m and reLmlating rods were considered. The fi-metional. expr e s: s ion ob t aine (3. from st aiidar d first- order pertm:bat ion theory was, the.reSore, Judged inadequate f o r r e p r e s e n t i n g Lhe i-od-rea c t i v i t y curves.

W e have found t h a t a s i g n i f i c a n t irriprovement in the fi-1; can be made by assurning t h . a t t h e a x i a l d i - s t r i b u t i o n of thermal f l u x , @2, i s pertu.rtjed according t o the p o s i t i o n of -the shi:n.-regulating r o d bank (Zl>b u t i s una f f e c t e d by the p o s i t i o n of t h e r e g u l a t i n g rod (Zz1. The approximate f o r n u l a for 02 used f o r t h i s analysis w a s :

02(z) =

@2(z)

D2B$

D2R$,

B -t-

A -t-

D,C 8 2P

D a2 2

s i n h CX z

sirih a ( H

DE$

z ) -1-

I f

DE;

EX2

sin

I -f-

lTZ â&#x201A;ŹI ,

sin

3lz H '

where

BT2 =

(;)

anti TI2 and >7

2 y

a r z y respectively, t h e t h e m i a l diffusi.on c o e f f i c i e n t and

t h e macroscopic thermal c r o s s s e c t i o n of t h e core i n t h e absencc of -tile c o n t x o l rods. The coeCY'icients A and B depend on the strength of t h e (1.1 shim- r e g u l a t i n g rod bank ab s o r p t i o n , 6Ca2', t o g e t h e r with geometric fat-

t o r s . They can be determined by requitring c o a t i n u i t y of flux a n d cureeilt a t t h e i n t e r f a c e , Z1, between 'the "rodded" arid "imrodded" r e g i o n s . The final. resu1.t of applying t h i s a n a l y s i s i n Eq. ( 2 ) was

where

... ,

The parameters C o y C1, t i o n s t r e n g t h s , 6Ca2

and 6 Z i z ) ,

were found t o depend on t h e rod. absorpt o g e t h e r with o t h e r macroscopic parame-

t e r s c h a r a c t e r i z i n g t h e r e a c t o r c o r e i n t h e absence of t h e r o d s . a d d i t i o n , i t w a s found t h a t

This l a , t t e r r e s u l t i s useful i n modifying expression (7) f u r t h e r , i n order t h a t l i n e a r l e a s t - s q u a r e s a n a l y s i s could be used t o determine t h e numerical v a l u e s of t h e paramrters. Thus,

By iiitroducing t h i s approximation i n Eq. (7) and r e d e f i n i n g t h e c o n s t a n t s , it was found t h a t

Expression (14.)was f i t t e d t o t h e experimental rod c a l i b r a t i o n curves, u s i n g s t a n d a r d l i n e a r l e a s t - s q u a r e s a n a l y s i s t o determine t h e ag. The p o s i t i o n of t h e rods r e l a t i v e t o t h e c o e f f i c i e n t s a0, e x t r a p o l a t e d zero of t h e unperturbed axial flux d i s t r i b u t i o n (Z = 0 ) i s

. .. ,

where Zo i s t h e ''zero point" i n s e r t i o n of t h e r o d s when withdrawn t o -their upper l i m i t I r e l a t i v e t o t h e e x t r a p o l a t e d zero of t h e ?lux d i s l r i b u t i o n , and XI,2 a r e t h e measured rod i n s e r t i o n s . Adequate approximations f o r t h e parame-ters c h a r a c t e r i z i n g t h e unperturbed f l u x d i s t r i b u t i o n , Zo, a, and 11, were obtained from earlier c o r e physics s t u d i e s . The r e s u l t s of t h i s a n a l y s i s a r e swmarized i n Table 3.1 and F i g . 3.1. I n F i g . 3.1 the rnagiiitxde of t h e rod r e a c t i v i t y i s plo-bted as a functio:n of rod p o s i t i o n f o r vario-us configgurations of shim and r e g d a t i n g rods. The ordinate scale i i i t h i s f i g u r e i:; a r b i t r a r i l y normal-ized t o z e r o measured r e a c t i v i t y when the r e g u l a t i n g rod i s fullry i n s e r t e d and t h e tvo shim rods are withdrawn to 5 1 i n . The leftmost curve r e p r e s e n t s t h e r e a c t i v i t y change when t h e r e g u l a t i n g rod i s moved with the shim rods f u l l y withckami. The rigti.trnost cu.r've represexts t h e c a s e when t h e t h r e e rods are rizoveCi i n a banked p o s i t i o n with the tips of t h e rods a t e q u a l eleva-Lioiis. The r e maining curves represent the r e a c t i v i t y change when t h e r e g v l a t i n g r o d i s moved with t h e shim rods h e l d f i x e d at; v a r i o u s i n t e r ~ ~ i . e t l i apt eo s i t i o n s .

86 The s o l i d curves a r e t h e r e a c t i v i t y magnitude c a l c u l a t e d From t h e l e a s t squares formula. The p o i n t s shown as s o l i d dots a r e sample p o i n t s d e t e r mined from t h e experimental rod c a l i b r a t i o n curves. Over most of t h e range of rod movement t h c c a l c u l a t e d and measured r e a c t i v i t y a r e i n agreement w i i h i a about 0.02’$ 6k/k. Near t h e extreme p o s i t i o n s of t h e Table 3.1. Numerical Values o f Parameters i n Ieast-Squares Formula f o r Control Rod R e a c t i v i t y (Eq. 1 4 ) l__ll.-.

Parameter

a, em-’

zo, crfl

H, em a0

Val-iie

-1.944 x l.0-7

0.082 24.6

5.891. x

1.98.5 2.125

0.1041

2.865 x

-0.3935

“2

-0.3585

“8

_.....

2.2

. -

lom8

-1.747 x -4.358 x lo-*

ORNL-OWG

........

66-4758

2.0

< -+ 1.6 -4

1.4

[L +

1.0

<.> k

0.8

w +

0.6 0.4

0.2 0

POSITION OF ROD MOVED

32 (in.

WITHDRAWN)

F i g , 3.1. Comparison o f Contzol Rod R e a c t i v i t y from F ~ p e s i m e n t a l Cilrves and from Least-Squares Formula.

rods t h e e r r o r i s somewhat l a r g e r . However, -the l e a s t - s q u a r e s formula should be adequate f o r automatic monitoring of t h e c o n t r o l rod r e a c t i v i t y

under most normal o p e r a t i n g circumstances.

S p a t i a l D i s t r i b u t i o n of 135Xe Poisoning i n !ERE Graphite To supplement t h e experimental s t u d i e s of t h e behavior of noble gas i n j e c t e d i n t o the E R E t h e o r e t i c a l c a l c u l a t i o n s were made t o determine t h e i n f l u e n c e of t h e spatial d i s t r i b u t i o n of 135Xe absorbed w i t h i n t h e g r a p h i t e c o r e . It i s expected t h a t t h e c o n c e n t r a t i o n of xenon i n -the s a l t w i l l be r e l a t i v e l y uniform throughout -the volume of circul.ation. However, w i t h i n t h e g r a p h i t e pores, t h e 13'Xe would t e n d t o assume an o v e r a l l s p a t i a l d i s t r i b u t i o n governed by t h e burnout r a t e i n t h e neutron f l u x . This d i s t r i b u t i o n would be concav-eJ with mininmm ccjncentration o c c u r r i n g near the p o s i t i o n of maximum thermal f l u arid rriaximum concent r a t i o n n e a r t h e boundaries of t h e r e a c t o r c o r e .

It i s intended t h a t tlie r e a c t i v i t y &LE t o L35Xe poisoning will be p e r i o d i c a l l y c a l c u l a t e d during o p e r a t i o n 'uy use or" tlie TRW-340 data l o g g e r . From a p r a c t i c a l s t a n d p o i n t we a r e l i m i k d t u t h e use of a r e l a t i v e l y simple "point" k i n e t i c s mode1 Tor o n - l i n e c a l c u l a t i o n s . Therefore, any c o r r e c t i o n s f o r the s p a t i a l d i s t r i b u t i o n of t h e 135Xe poisoning must be predetermined from t h e o r e t i c a l ctudie:; with a nore e l a b o r a t e model oâ&#x201A;Ź t h e r e a c t o r c o r e .

If we c o n s i d e r a s t e p change from one '7ower l e v e l to another, .the c o r r e c t i o n f o r t h e spa-tiall ( 3 1 s t r i b u t i o n of i35Xe w i t h i n t h e g r a p h i t e region cam be determined from

(16)

Po, PI = i n i t i a l and f i n a l p o i ~ e rlevels, -t time a f t e r power l e v e l i s changed., :L

@1(r) = thermal P:lux a t p o s i t i o n r r e l a t i v e t o the c e n t e r of t h e core a f t e r the porvTer level. i s changed, $1 =

!NX e [ 01(1-), t 1 -7

thermal. flux a f t e r t h e poWer l e v e l i s changed, averaged over t h e graphite volutrie,

= loca11.y averaged 1 3 5 ~ ec o n c e n t r a t i o n i n graphi.te

a t position r and time t ,

-E

NXe

(01, t) I= local1.y averaged 135Xe c o n c e n t r a t i o n i n g r a p h i t e a t time t , corresponding t o a f i c t i t i o u s "fl.at" neutron f l u x d i s t r i b u t i o n equal. t o t h e s p a t i a l l y averaged f l u x , @

(r) = normalized di.sl;ributri.on of thermal flux,

@"(i-) =

normalized d i s t r i b u t i o n of thermal group importance (ad-joint f l u x ) ,

As defined by Eq. (161, FJ i s t h e f a c t o r by which t h e 135Xe reac'Givity c a l c u l a t e d according t o a 'fpoint'' k i n e t i c s model must b e m u l t i p l i e d -to accoun"i f o r Lhe s p a t i a l d i s t r i b u t i o n of t h -e poisoning. I n t h i s equation 5 ~ concentration, e NZe, i s t h e r a d i a l average over t h e "l.ocal average 'I Lhe gra,pb.ite volume a s s o c i a t e d with a s i n g l e f u e l channel. It i s u s e f u l t o compute t h i s q u a n t i t y b e f o r e performing t h e i n t e g r a t i o n s over the e n t i r e core g r a p h i t e volume i n d i c a t e d i.n Eq. (16). Althou-gh n e a r l y a l l t h e xenon i n t h e g r a p h i t e would be expec-Led t o be i n t h e pores nearest, t h e g r a p h i t e - s a l t i n t e r f a c e , t h i s local. averaging procedure can be used because t h e r a d i a l v a r i a t i o n of neutron f l u x ac.ross a s i n g l e g r a p h i t e stringer i s negligible.

We have used a one-dirrieiisional model. f o r t h e f u e l ciiaimels i n o r d e r t o s i m p l i f y t h e c a l c u l a t i o n s . The f u e l and g r a p h i t e widths corresponding t o a s i n g l e channel were chosen so t h a t t h e r a t i o s of mass t r a n s f e r surf a c e area to volumes were equal t o t h o s e of the actual. channel. The eyiiatj-ons governing t h e production and m a s s t r a n s f e r for 135Xe between t h e s a l t and g r a p h i t e were :

I n t h e s e equations

t ) = l o c a l c o n c e n t r a t i o n o f 'j5Xe a t p o s i t i o n x w i t h i n t h e

i\l!e(x,

g r a p h i t e s t r i n g e r , measured from t h e g r a p l i i t e - : ~ a l t i n t e r f a c e , atoms per cubic centimeter of g r a p h i t e ,

-R

= local c o n c e n t r a t i o n oI" 135Xe, averaged over t h e g r a p h i t e volume associa-Led with a s i n g l e f u e l channel.,

DJxxe(t)

-R

NI,Xe

= average c o n c e n t r a t i o n of 1351 and 135Xe i n t h e c i r c u l a t i n g f u e l s a l t , atoms per cubic centimeter of l i q u i d ,

of 135Xe i n s a l t nearest, t h e g r a p h i t e i n t e r f a c e , d i r e c t l y exposed t o t h e g r a p h i t e pores, a t o m per cubic c e n t i m e t e r o f l i q u i d ,

= concentration

= f i s s i o n deiisity i n core s a l t , f i s s i o n s per cubic c e n t i -

meter of l i q u i d p e r second.,

O ( r ) = thermal neutron f l u x a t p o s i t i o n r, measured from t,he sec-I. c e n t e r o f tlie g r a p h i t e c o r e , neutrons

'1 Xe = f i s s i o n y i e l d of 1351 and 135Xe

135S and 135Xt3,

= r a d i o a c t i v e decay c o n s t a n t s f o r

%,Xe

= e f f e c t i v e '35Xe

A S D

see-',

removal r a t e ciue

-LO

sec-1

external stripping,

= thermal neutron a b s o r p t i o n ( x o s s s e c t i o n of I3%e,

cm2,

Dg = d i i ' f u s i v i t y of xenon i n g r a p h i t e , square centirfleters Xe of g r a p h i t e p e r second, h = rnass t r a n s f e r c o e f f i c i e n t f o r Liquid. film a t t h e g a p h i t e- salt i n t e r f a c e crn/sec

yo = half-width o f s i n g l e fi.ieI channel,

em,

y1 = half-wl.dth of g r a p h i t e a s s o c i a t e d with a s3.ngl.e fuel c h a m e l , cmP

Vc/VL

salt, w i t h i n t h e graphite-moderated r e g i o n t o t h e t o t a l volume csf c i r c u l a t i n g s a l t .

= r a t i o of volume OS

Boundary c o n d i t i o n s are reqv.i.red t o solve the d i f f e r e n t i a l equations (18) and (151, A t the o u t e r boundxqj of t h e gi-aphite associ.atcd vith a s i n g l e f u e l channel,

(21)

90 A t the graphite-salt interrace,

where @ = RT/HXeâ&#x201A;Ź, R = u n i v e r s a l gas constaint,

= temperature,

E =

82-07~ 1 1 1a ~t m mole**' (OK)-",

OK,

g r a p h i t e p o r o s i i y , cubic centi.mete:rs of void per cubic c e n t i meter of graplii t e .

At 'Lime t = 0, eqiri.librium c o n d i t i o n s corresponding t o t h e i n i t i a l power l e v e l ( P O ) were a,ssumed. The i n i t i a l concciitra1;ions a r e t h e solut i o n s of E q s . (1.7) through (23), w i t h t h e t t m e d e r i v a t i v e ; e c p a i t o zero. For Lrimes following t h e change i n power l e v e l , t h e d i f f e r e n t i a l equations w e r e solved by means of Laplace transforms. A s u f f i c i e n t approximation t o t h e exact solubion w a s o b t a i m d by use of the c o n d i t i o n

P1iy~lcal.l.y~ t h i s c o n d i t i o n implies Lhat most of t h e r e s i s t a n c e t o m a s s transf'er between s a l t and g r a p h i t e ri.s due t o t h e f l u i d film. R e s u l t s of krypton ri.njection experimen-ts appear t o s u p p o r t tiiis concI.iision.2* Some t y p i c a l nuiiiierical cal.culations based on t h e preceding model a r e g:i:veu i n Figs. 3 . 2 and 3.3. Nmerical. vahres t o r t h e e f f e c t i v e mass t r a n s f e r coefficien-b, s t r i p p i n g r a t e , and g r a p h i t e p o r o s i - t y c h a r a c t e r i s t j . c s were obtained from r e f . 3. E'igure 3.2 shows t h e time v a r i a t i o n of the c o r r e c t i o n f a c t o r , W, as t h e power l e v e l ascends t o 2.0 Mw. I n t h e l i m i t ing case of a s t e p change from 0 t o 10 Mw, W decreases monotonically t o an equilibrium value of approxiiii.ately 0.76. Curves are a l s o given for t h e case when t h e power l e v e l i s increased. j.n sinccessive s t e p s , each time

â&#x20AC;&#x2122;31 ORNL-C)WG 66-4759

TIME ( h r )

Fig. 3.2. T i m e Dependence of t h e S p a t i a l Correction for t h e 135Xe Poisoning in MSm Graphite : Ascending Poser Level

ORNL-DWG 66-4760

...,........

......

1.0-0

TIME ( h r )

.......

F i g . 3 . 3 . Tiiiie Dependence of t h e Spatial Correction f o r t h e 135Xe Poisoning i n MSRE Graphi-be : Descending Power Level.

92 a1low.j-ng equilibrium poisoning conditions t o p r e v a i l b e f o r e f u r t h e r i n c r e a s i n g t h e power. The i n i t i a l "dip" i n t h e curve r e p r e s e n t i n g tile 5 t o 10-Mw s t e p i s a consequence of t h e r e l a t i v e time lag between t h e i n c r e a s e i n tile burnout r a t e i n .ihe g r a p h i t e aizd the i n c r e a s e i n t h e p r o duction r a t e of 135Xe i.n t h e s a l t . Fligwe 3.3 gives t h e analogous resul.t,s f o r power l e v e l s descending from 7.0 I&. F u r t h e r studi.es wi1.1. be made with t h i s t h e o r e t i c a l model i n order t o determine t h e s e n s i t i v i t y of t h e cal.culated c o r r e c t i o n s t o t h e zffcc-Live m a s s t r a n s f e r c o e f f i c i e n - t aiid. s t r i p p i n g r a t e , and t o determine t h e b e s t me-Lhod of intrcodixing t h i s cor~ectri.oni n t o t h e on-line ca3.cula.t i o n of t b e 1 3 5 ~ ree a c t i v i t y .

1. The Heactor Handbook, v o l . 111, Pal% A ( Y h y s i c s ) , ed. by h. Soodak, pp. 204-6, I n t e r s c i e n c e , New York, 1962. 3.

MSR Program Semiam. Progr. Rept. Feb. 28, 1965, ORNT,-3812,

H. J. Ked!.,

personal c o m u n i c a i i o n , January 1966.

pp. 12-14.

Part 2 ,

MATmvIl;S STUDIES

METALLURGY

Dynamic Corrosion Stuclies A test program i s i n progress t o study t h e compatibil..ity of s t r u c t u r a l m a t e r i a l s with fuels and coolants of i n t e r e s t t o the Molten-Salt %actor Program. Thermal convection loops described previously’* are used as the staildard test i n t h i s program.

C i r c u l a t i o n of l e a d i n a Cb-l‘$ Zr a l l o y thermal convectirm loop-3 was terminated a f t e r 5280 h r . Thi.s loop operated. with a hot-leg ternperatinre of 1400°F’and a 400°F AT. Metallographic examination of the bot leg, shown in Fig. 4.1, r e v e a l e d no evidence of a t t a c k ; however, a smna1.l q u a n t i t y of d e n d r i t i c c r y s t a l s was observed i n t h e cold leg. E l e c t r o n probe a n a l y s i s i n d i c a t e d these c r y s t a l s t o he c01umbiiu~~1,as Mass transfer of coltuabiuu i n l e a d has not been reshown i n Fig. 4.2. ported. previously.

Two 2-.2/4.$ CY-^.$ !qo steel thermal convtxtion I.0ops re started wi.tlz lead coolant t o stu.dy the e f f e c t of rnugnesium sdd.i.tions on mass

--. . k i y . 4.1. Section Through t h e Rot Leg of a Cb-1% Z r Loop Wnich Operated with Lead f o r Over 5000 hr at 1400°F.

LIGli.1 OPTICS

COLUMBIUM La X-RAY

IMAGE

Fig -. 4 . 2 . R e s u l t s of Electron Probe Analysis Showing Presence of Col.umbium C r y s t a l s on the Co1.d of‘ a Cb-l$ Zr Loop Which Operated f o r Over 5000 h r w i Y n a Hot-Leg Temperature of 1400°F and. a 400” LU’. 250X.

Reduced. 35%.

t r a n s f - r of primary elements. The loops w i l l operatc with a hot-leg temperature of 1100°F and a 200” LXLl. Magnesium w a s added t o a c i as a deoxidizer and an i n h i b i t o r . h o r i k i n a l plan t o include t i t a n i u m i n t h e l e a d w a s deferred because of d i f f i c u l i y i n making a Ti-E”u a l l o y . V J O1 oops con”Laifling mol-ten f l u o r i d e s colitinued t o operate without i n c i d e n t . A type 304 s t a i n l e s s s t e e l loop with removable specimens has o p ~ r a t e dfor 22,000 hr, and a Hastclloy N loop containing specimens of Hastclloy N modified with 2% (91 has operated f o r 33,000 h r .

MSRE Materi.al S u r v e i l l a n c e Tests

R e actor Survei ll~anceSpecimens

Specimens o f Bastelloy N and grade CGB g r a p h i t e were exposed for approximate1.y 1100 h r t o molten f l u o r i d e s a l t s i n the core of t h e MSRE during the p r e c r i t i c a l operation and t h e i n i t i a l c r i t i c a l and a s s o c i a t e d zero-power experiments. m e purposes f o r tiiese were: (I) t o monitor materia1.s during t h e s e p r e l i m i m r y operations and ( 2 ) ’LO be the mass equivalent f o r t h e s i m i l a r specimens t h a t r e p l a c e them f o r siirveiI.l.ance of t h e power experiments.3 These spzcimens showed no changes as a resill-t of exposure during t h e s e S i r s t , mild experiments.

97 The g r a p h i t e specimens were nominally 0.8-in.-dia.m by 10-in.-long rods. They were machined f r o m ME53 g r a p h i t e , grade CGB, having a relat i v e l y high c o n c e n t r a t i o n of cracks, w i t h t h e id.ea t h a t t h i s would magnify a,dverse chacges t h a t might occur i n t h e r e l a t i v e l y short, m i l d exposure. There mi::; e s s e n t i a l . l y no s a l t on t h e yraphil;e, and t h e inachining marks ap.peared u n a l t e r e d . A s i n the 1 . a b o r a t o q t e s t s , radiographs showed t h a t surface-connected c r a c k s tended t o be filled. w i t h s a l t , w i t h no s a l t p e n e t r a t i n g i n t o t h e graphite. The volume of s a J t i n t h e g r a p h i t e averaged 0.06% of t h e bulk volume of the g r a p h i t e , vhich i s approxintately one-tenth of t h e maximum p e r m i t t e d Fn t h e MSRE design s p e c i f i c a t i o n s . The rela-Lively s m a l l dimensions OP t'ne specimens and t h e presence of a r m r e - t h a n - t y p i c a l q u a n t i t y of c r a c k s would t e n d t o give abnormally high s a l t pickup. The I l a s t e l l o y N specimens, i n the form of t e m i l e specimen rods, a l s o d r a i n e d f r e e of salt;. They liad l o s t t h e i r b r i g h t , shiny, machined su.rface and had a b r i g h t , g r ~ ~ y - t r h i tmatte e s u r f a c e s i m i l a r to that obt a i n e d i n hydrogen f i r i n g of t h e m e t a l .

F i g . 4 . 3 . Microstructure of i l a s t e l l o y N T e n s i l e Specirncn Exposed i n MSRE During Zero-Pmer T e s t i n g of Reactor. Microstructure i s extremely f i n e g r a i n e d . Black band approxiinately 0.0005 in. below surface i s 0.0005 i n . wide and i s composed of g r a i n s whose boundaries have been eririched or d e p l e t e d i n some c o n s t i t u e n t . Etchant : aqua regia.

98 Two of t h e specimens were sectioned and were examined met;al.lographic a l l y . For comparative purposes, two c o n t r o l specimens o f t h e same composition were a l s o examined. Longitudinal. and t r a n s v e r s e s e c t i o n s of t h e shoul.der and gage-length regions of t h e Lznsile specirnens were examined. B o t h t h e t e s t e d and controll. specimens e x h i b i t e d extremely f i n e grained m i c r o s t r u c t u r e ( s e e F i g s . 4.3 and 4.4.). The gi-arin boundaries i n a 0.0005-in. band approximately 0.0005 i n . below t h e s u r f a c e of the t e s t e d specimens were darkened.. It appears t h a t t h e boundaries were perhaps e i t h e r d e p l e t e d or enriched i n some unknown c o n s t i t u e n t . A s e c t i o n of a tes-Led s u r v e i l l a n c e specimen has been submitted f o r airalys-is with t h e e l e c t r o n microprobe aiia3yzer; howevzr, -ihe a n a l y s t s has not been completed y e t . A longi-Ludinal vTew OS t h e con’mol specimen i s shown i n Fi.g. 4.5. Toe m i c r o s t r u c t u r e of t h e c o n t r o l specimen ind-icates t h a t t h z suyvei3.lance s:pecimens were i n a s e v e r e l y worked c o n d i t i o n p r i o r t o t e s t i n g . During exposure i n t h e r e a c t o r a t approximately 1.200°F, t h e a l l o y r e c r y s t a l l i z e d t o t h e smaller grai-n s i z e shown i n F i g . 4.3.

Fj.g 4.4. K i e r o s t r u c t u r e o f Control HasteUoy N T e n s i l e Specimen. Although Lhe m i c r o s t r u c t u r e i s extremely f i n e grained, t h e specimen i s c o a r s e r grained than the one removed from t h e MS€?Es a

Longitudinal. View of Control lhsteZLoy i'l Teiisile SpecFmen. F i g . 4.5 P&.crostructure indicates that specimefi was in s e v e r e l y worked cojjdition %-tchant: aqua regia e

Si.r v-eiilance Control Specirwns

The r e a c t o r control. specimen. t e s t i m i t wi.17. copy changes of t h e reactor operation, as specified i:iuoTiY7 through direction:: r.c-lzyied t~ i i ; by the eorqxter t h a t monitors the MGRE. Cal.ibra-l;ion of t h e i m i t w i t h the co1qmter i s i n progr*~-.ss.

100 Hot-Cell Me’calloaraDhic Examination OP ~Haste:.lovu -N u *-from Experiment, MTR-47-6 f o r Evri dence of N i t r i d i n g _ I

When t h e NYRE i s operatlng, the atmosphere in t h e r e a c t o r c e l l andthe d r a i n t a n k c e l l w i l l be n i t r o g e n c o n t a i n i n g about 3s OXygeil. There has been some concern t h a t t h e ni’ciwgen, when i o n i z e d by r a d i a t i o n , w i 3 . 1 ni.l;r<.de and mibrj.ttle t h e IIaste3.3-oy TJ o f Lhe r e a c t o r components. Since t h e capsules i n experiment ORNL MY€?-47-6 were cooled with a i r and w i t h a i r and n i t r o g m mixtures during i r r a d i a t i o n , we examined t h e bottoiils of capsules 1 and 2 f o r evidence of n i t r i d i n g of I i a s t e l l o y under i r r a d i a t i o n . The capsules were contained i n a copper h e a t e r b l o c k s o t h a t only t h e Lops and bottoms were exposed t o n i t r o g e n . Construction o f t h e capsul.es and the o p e r a t i n g condftions during f r r a d i a t i o n have been reported.‘ Unfortuna-tely, t h e o u t e r s u r f a c e s oT t h e bottoms were damaged during i n i t i a l . disassembly o f t h e capsul.es a t t h e MTR hot c e l l s . Machi.ned grooves on t’ne capsule bottoms were s t i l l visri.’n.e, and t h > bottoms

Pig. 4.6. B o t t o m of the Machiried Groove on the Bottom of Capsule 2,‘ M’IK-47-6. A t h i n oxide scale i s v i s i b l e on t h e exposed surla,ce; t h e r e i s no evidence of n i t r i d i n g . Etchant: aqua r e g i a .

1.0 1.

10% Table 4.1.

Wa3.1 Thickness of Control Capsul.es and Capsules I r r a d i a b e d i n Expe-rinent O W L MT13-J:.rt-6

Capsule N o .

Wall Thickness

(in.)

Control, t e s t e d under same conditions as i r r a d i a t e d capsules

0.0525

Control, spare capsule

0.0515

Capsule 1 (ORNL MTH-47-6)

0.0.525

Capsule 2

0.0530

Capsule 3

0.0515

Capsu.1.e 4

0.0525

F i g . 4.7. Microstructure of Inner Surface of H a s t e l l o y N CapsiAe Capsule 2, Experiment MTR-47-6, LongLtudinal. View. Grain bounda r i e s a t s u r f a c e a r e cl.arkened t o a depth of 0.005 3.n. Also note finegrai-ned. m i c r o s t r u c t u r e of K a s t e l l o y N * Etchant : aqua reg-La

Wall-,

103

F i g , , 4.8. fvlicrostructure of Inner Swrface of iIastelLoy N Capsule Wall from Control Capsule T’nat Was Tested Out of P i l e Under Sane Condit i o n s as Irradiated Capsules, Longitudinal View. Also note f i n e - g r a i n e d m i c r o s t r u c t u r e . Etchant: aqua regia. 1.b i s h i g h l y desLrable t o j o i n g r a p h i t e pipes i n the r e a c t o r core t o Hastelloy N headers. The b a s i c o b s t a c l e encountered i n i%ttenlptixlg such a Join-i; i s t h e very large d i f f e r e n c e between Lhe tiierrrial expttnsioa coeff i c i e i i t s of t h e gra’phite a n d -the metal.. Due t o t h i s dLfference, a j o i n t of g r a p h i t e d i r e c t l y brazed t o €€astell.oy M cracks upon coolirig from the b r a z i n g temperature. One possible method o f circumventing t h i s problem i s t o make t h e - t r a n s i t i o n w i t h one o r more niaterials having expansion c o e f f i c i e n t s in-kermediate between t h o s e o f the g r a p h i t e and HasteI.loy IT. This reduces t h e stress gradienLs. Thus, t h i s program i s concerned with t h e development of t r a n s i t i o n pieces, as well as accepta-ble brazing

alloys.

Molybdenum and Lungsten a r e two metals which have expansion coeff i c i e n t s ifltermediate between t h o s e of g r a p h i t e and Hastelloy TT, and were s e l e c t e d f o r f u r t h e r study. However, due to c o s t and a v a i l a b i l i t y cons i d e r a t i o n c , n e a r l y a l l work was pprforraed on rnolybd~eniun. Thi:; d e c i s i o n was f u r t h e r jim-cified by t h e fact t h a t nearly all a l l o y ; wliich b r a z e molybdmxun w i l l also braze tungsten.

104 S t u d i e s are being conducted, using t h e newly designed t r a n s i t i o n j o i n t presented i n Fig. 4.9. The d e s i s n i n c o r p o r a t e s an ].lo t a p e r e d edge t o reduce shear s t r e s s e s a r i s i n g from t h e thermal expansion d - i f f e r ences. This 'cechnique may enable t h e j o i n t between t h e molybdenum t r a n s i t i o n piece and t h e HasteI.loy N to be made d i r e c - t l y , t h a t i s , witho u t another t r a n s i t i o n . Several. assembli.es a r e being prepared f o r evalua t i o n of b r a z a b i l i t y and e f f e c t s of thermal cycl.i.ng.

'TheOFUVL-developed b r a z i n g all-oy, 35 flu-35 Ni-30 Mo (w% $J), i s very u s e f u l f o r b r a z i n g graphite; however, transmutation of the gold may 2.im.j-t i t s a p p ? ~ i c a t i o ni n a high nzukron f l u x . Consequently, a study was undertaken t o develop a gold-free brazing al.loy which i s com:pati.ble with molten s a l t s , c o n t a i n s a carbide former, and has a reasonably low melting p o i n t . Tests of Graphite-Molybdenum Brazed J o i n t f o r Containing Molten S a l t s Under Pressure A flirst t e s - t w a s conducted i n which a s i n a l l pipe of grade CGB graphi t e , brazed to molybdenum, contained molten f l u o r i d e s a l t s at 700째C under pressures of 50, 100, and 150 p s i g f o r periods of 100, 1-00, and 500 h r r e s p e c t i v e l y . T h i s test, which operated s a t i s f a c t o r i l y d e s p i t e a pr3.rnj.t i v e j o i n t design a n d a r e l a t i v e l y thin-walled. graphike pipe, siuggests t h a t l a r g e r graphite-metal joints may be f e a s i b l e f o r molten-salt breeder r e a c t o r s . Cu-rrent M.333 designs have a ma.x-imimi pressure d i f f e r e n c e of 30 p s i a c r o s s pipe walls, l e s s t h a n o n e - f i f t h t h e maximum pressure used i n this test.

The t e s t c o n f i g u r a t i o n i s shown in Fig. 4.10. The short g r a p h i t e pipe, 1.25 i n . OD x 0.75 i n . ID X 1.00 i n . long, was machined f r o m a b a r of MSRF g r a p h i t e wTth i t s a x i s paral.le1 Filith t h e e x t r u s i o n d i r e c t i o n of t h e b a r . f i r e molybdenum caps were brazed t o ilie ends of t h e pipe by t h e Welding and Brazing Group of t h e Metals and Ceramics Division with 3 5 Au-35 Ni-30 Mo (ANTI-16) (in w t $J) braze, which i s one o f their e a r l i e r developments in braziiig alloys.

GRAPHITE

ANGLE

ORNL-DWG 66-4774

HASTELLOY N

MOLYBDENUM

CONCENTRIClrY:

j, 0 001 in.

A L L ANGLES SAME AS THE ONT OETAILED SPECIMENS ARE

474-in

OD LVITH A

A8OVE

3/rs-~n. WALL

F i g . 4.9, Schematic Drawing of Proposed Graphite-Lu-HasteLloy J o i n t Using a Mol-ybdeuum T r a n s i t i o n Piece.

105

ORNL-DWG 66-4775

METAL-SHEATHED

THERMOCOUPLE <

TO VACUUM

INCONEL Y67886

PRESSURE

PROTECTIVE CONTAINER

OPEN-END THERM MEASURES TEMPERATURE AND DETECTS SALT LEAKAGE INCHES

Fig. 4.10. Test for Small. Graphite Pipe and Graphite-Metal J o i n t s .

106 The molten salt was f e d t o t h e e l tube brazed i n t o t h e t o p The s a l t w a s p r e s s u r i z e d by a cover maintained a pressure of <5 p. Hg i n and t h e p r o t e c t i v e c o n t a i n e r .

i n s i d e of t h e g r a p h i t e pipe through molybdenum end cap (see Fig. 4.11). gas of pure a r A v a c u m pump t h e annulus between t h e g r a p h i t e pipe

ranee of t h e o u t s i d e of t h e pipe was e s s e n t i a l l y u n a l t e r e d These photographs a l s o show t h e good ee Fig. 4.11b). phite. A small c i r c e e r wetting of t h e brazes t o t h e metal and s e p a r a t i o n of t h e braze and t h e g r a p h i t an be Seen a t t h e bottom next t o t h e g r a p h i t e . Microscopic examination i n d i c a t e d t h a t t h e e f f e c t i v e bonding and s e a l i n g w a s i n t h e c r e v i c e between t h e pieces. Minor cracking tended t o be confined t o t h e f i l l e t s . The microscopic examina'$) braze w e t t h e grapht i o n s , a l s o , showed t h a t t h e 35 Aw35 Ni-30 Mo ( i t e b u t d i d not n e t r a t e i t s s t r u c t u r e . The b r s a l t xF-BeF2-fiF4of a t t a c k by t h e molten f l u o r not show any s i ThF4-uF4 (70-23-5-1-1 mole %). The 50 A-50 N i ( w t 5 ) braze used t o j o i n t h e molybdenum t o t h e Inconel s a l t - s u p p l y tube bonded s t r o n g l y t o t h e I r e c t i o n t r a n s v e r s e t o t h e r o l l i n g d i r e c t i o n of t h e molybdenum, a f e w

107 molybdenum g r a i n s were p u l l e d o u t a t t h e molybdenum-braze i n t e r f a c e . This was n o t apparent i n t h e as-brazed m a t e r i a l and w i l l be s t u d i e d more thoroughly a s t h e work p r o g r e s s e s . The radiograph i n F i g . 4.12 shows t h a t none of t h e s a l t p e n e t r a t e d t h e m a t r i x of t h e g r a p h i t e . This i s c o n s i s t e n t with p a s t experience w i t h t h i s small-pore-size, high-density grade CGB g r a p h i t e used i n t h e

Msm .

New Grades of Graphite Procurement and s t u d i e s of grades of g r a p h i t e p o t e n t i a l l y promising f o r a m o l t e n - s a l t b r e e d e r r e a c t o r a r e i n t h e i n i t i a l s t a g e s . Attempts a r e b e i n g made t o o b t a i n g r a p h i t e s u i t a b l e f o r i r r a d i a t i o n s t u d i e s i n o r d e r t o secure t h e r e q u i r e d i r r a d i a t i o n exposures nvt, E > 0.18 MeV) reasonably soon. Samples of needle-coke g r a p h i t e and i s o t r o p i c g r a p h i t e a r e b e i n g t e s t e d . A needle-coke g r a p h i t e w a s used i n t h e MSRE t o minimize i r r a d i a t i o n c o n t r a c t i o n and a s s o c i a t e d s t r e s s e s . I s o t r o p i c

F i g . 4.12. Radiograph of Thin S e c t i o n s Machined (a) Transversely and (b) L o n g i t u d i n a l l y from t h e Graphite-Molybdenum Brazed J o i n t T e s t Showing That N o S a l t P e n e t r a t e d i n t o t h e Graphite Pipe Walls. (Salt would appear h e r e as a w h i t e phase.)

108 g r a p h i t e has been included i n t h e s e s t u d i e s because it may be s u p e r i o r i n mechanical p r o p e r t i e s and more r e s i s t a n t t o damage under t h e high exposures r e q u i r e d i n t h e MSBR. * *

â&#x20AC;&#x2122;

A p a r t of t h i s e f f o r t i s t o o b t a i n g r a p h i t e with t h e c o n f i g u r a t i o n r e q u i r e d f o r c u r r e n t designs of molten-salt breeder r e a c t o r s . This i s being done because t h e shape and s i z e can s i g n i f i c a n t l y a f f e c t t h e f i n a l p r o p e r t i e s t h a t can be b u i l t i n t o t h e g r a p h i t e . Current designs r e q u i r e g r a p h i t e pipe nominally 4 i n . OD x 3 i n . I D x 8 t o 12 f t long and 2-1/2 i n . OD x 1-1/2 i n . I D x 8 t o 12 f t long. Secondary a t t e n t i o n i s given t o t h e small-scale laboratory-produced materials.

The prime requirements of t h e g r a p h i t e f o r t h e i n i t i a l procurement a r e t h a t it have pores s m a l l enough t o prevent t h e e n t r y of molten s a l t s and t h a t it have a low gas permeability. The pore entrance diameters should be l e s s t h a n 0.5 p, and permeability t o helium a t 1 a t m of press u r e should approach cmz/sec. The s u p p l i e r s c u r r e n t l y propose mat e r i a l with a permeability i n t h e range of t o lom3 cm2/sec, with t h e higher values being favored.

To d a t e we have obtained g r a p h i t e samples from t h e Carbon Products Division of t h e Union Carbide Corporation, Great Lakes Carbon Corporation, Poco Graphite, I n c . , Speer Carbon Company, Stackpole Carbon Company, and t h e Y - 1 2 Chemical Engineering Group of t h e Development Division. The material obtained from t h e Carbon Products Division i s a needlecoke g r a p h i t e , and t h e materials obtained from t h e o t h e r s a r e i s o t r o p i c g r a p h i t e . Short p i e c e s of pipe 4.7 i n . OD X 3.5 i n . I D and 3.6 i n . OD X 2.5 i n . I D have been supplied by t h e Great Lakes Carbon Corporation and t h e Carbon Products Division r e s p e c t i v e l y . The m a t e r i a l s from t h e o t h e r s were rods o r blocks.

To determine i f t h e s e grades of g r a p h i t e (and f u t u r e grades) are p o t e n t i a l l y u s e f u l f o r an MSBR, we a r e r o u t i n e l y examining them f o r t h e entrance diameter spectrum of t h e a c c e s s i b l e pores, permeability t o helium gas, permeation by molten f l u o r i d e s a l t s , microstructure, s p e c i f i c r e s i s t a n c e , f l e x u r a l s t r e n g t h , and c o e f f i c i e n t s of thermal expansion. The c u r r e n t samples a r e i n t h i s s t a g e of examination. Those t h a t appear t o have promise w i l l be given a d d i t i o n a l t e s t s f o r p u r i t y and c r y s t a l l o graphic development and w i l l be included i n t h e i r r a d i a t i o n s t u d i e s and graphite-metal j o i n t development mentioned previously. Evaluation of t h e E f f e c t s of I r r a d i a t i o n on Graphite Recent progress i n t h e development of g r a p h i t e f o r r e a c t o r use may be a p p l i e d d i r e c t l y i n e s t i m a t i n g p r o p e r t i e s of a g r a p h i t e designed f o r t h e MSBR. There are, of course, s e v e r a l unknowns which l i m i t t h e a b i l i t y t o s t a t e c a t e g o r i c a l l y t h a t any g r a p h i t e w i l l withstand t h e MSBR environment. The major l i m i t a t i o n i s t h e l a c k of evidence t o demonstrate t h a t any g r a p h i t e can s u s t a i n massive doses of nvt o r g r e a t e r and s t i l l

1.09 r e t a i n i..ts integri-by. The t u b u l a r thin-Tdal.l. design i n the IGBK i s one of t h e be-Lter c o n f i g y r a t i o n s f o r reducing the d i f f e r e n t i a l - g r o v t h problein to wi-thin t h e caps-oilities of t h e g r a p h i t e . The t u b u l a r shape i s a l s o easy Lo f a b r i c a t e and t o t e s t r e l i a b l y and n o n d e s t r u c t i v e l y i n order t o ensure maximuni i n t e g r i t y . The p r o p e r t i e s o f t h e :most promising grade of graphi-Le c a n be proj e c t e d from a v a i l a b l e grades wi-th a f a i r degree o f c e r t a i n t y (see Table 4 . 2 ) . ‘These e s t i m a t i o n s a r e based p r i m a r i l y on p r o p e r t i e s obtained from i s o t r o p i c grades with d e n s i t i e s r e q u i r e d fox- t h e MSBR grade.

The magnitude o f t h e stress generated by d . i f f e r e n t i a 1 grow’iin can be fa.ir3-y w e l l approxim.ated. The main. u-ncei-tainty i s i n t h e f1.ux g r a d i e n t a c r o s s t h e tube w a l l . Using t h e conservative e s t i m a t i o n of 2.4 x i n . . in.””’ nvt-l as t h e growth r a t e and a 10% change ~ J I f1.ii.x across t h e w a l l , a d i f f e r e n t i a l growth rate of 2.4 X l.0--25 i n . in.”=’ nv-t-’ i s obta.ined. The r e s t r a i n t i s i n t e r n a l ; t h e r e f o r e , only a’oout h a l f of t h e d i f f e r e r i t i a l growth i s r e s t r a i n e d , s o t h e e f f e c t i v e s t r a i n r a t e i s 1..2 x in. in.-’ n-v-t-’

The c r e e p r a t e c o e f f i c i e n t ri.s 4 x i n . in.-’ t h e s t r e s s i s simp1.y and d i r e c t l y - c a l c u l a t e d t o be

-E-

1-2x

I -

4 x

= 30 p s i

psi-’

nvt-’,

and

This s-Lress could hardly be a cause f o r f a i l u r e , and t , 0’otari.n ~ stresses ii1 excess o f 100 psi would r e q u i r e t h e use o f g r o s s l y u n r e a l i s t i c maL L w i a l . properties. F a i l u r e , however, could r z s u l t f r o i n t h e i a a b i l i t y of tile g;raphl.te -to absorb c r e e p defamation even though t h e s t r e s s level. i s much less t h a n -the f r a c t u r e s t r e s s . For l i f e t i m e s of 1 . 5 x lo”, 3 x and 6 X 1 . 0nvt, ~ ~ t h e s b r a i n t o be absorbed wou.1.d. be about 1.8, 3.6, and 7.2% r e s p e c t i v e l y . This corresponds t o 5 - , lo-, and 20-year l i f e t i m e s with a dose r a t e of 9 X lo’“ nv, t h e maxirrtum f a s t f l u x i n -the p r e s e n t design of t h e MSRR. The c o n s i d e r a t i o n of a s t r a i n l i m i t f o r f a i l u r e i s r e a l i s t i c ; howeve:!., t h e s t r a i n l i r n i i ; Tor f r a c t u r e has not been eatabl i s h e d . It has ’men demonstrabed. t h a t graphi-be can abSoi% s t r a i n s i n excess o f 2% i n n-rt without l o s s of mecl1an3.cal i n t e g r i t y . There i s nvi; a l s o soiiie evidence t h a t t h e growth r a t e w i l l dimiriish a f t e r a dose; t h u s , t h e g r a p h i t e mighl; n o t be f o r c e d t o absorb t h e t o t a l . q u a n t i t y of st.!’a-in. c a l c u l a t e d . Therefore it appears t h a t f a i l u r e by reaching a s t r a i n l i m i t will r e q u i r e a t l e a s t f i v e y e a r s of s e r v i c e .

The main u n c e r t a i n t y , as mentioned e a r l i e r , i s simply the a b i l i t y of t h e g r a p h i t e t o s u s t a i n t h e massive dose without l o s s of .i.ntegrity. There i s no experimental evidence beyond 2 X nvt on which to e x t r a p o l a t e t h e i r r a d i a t i o n damage of g r a p h i t e , so e x t r a p o l a t i o n of d a t a to lo2’ woii.ld be pure c o n j e c t u r e . There are, on. t h e o t h e r hand, s e v e r a l f a c t o r s which f o r c e one t o be o p t i m i s t i c about t h e a b i l i t y o f g r a p h i t e .Lo smstaiii t h e

Table L;..2. ~~

P r o p e r t i e s of Advsnced Reactor Grades of ,Sraphite

Grade

Property

Density

1.80

%OOO

Bend s t r e n g t h , p s i Plodulw of e l a s t i c i t y , p s i Thermal con&dc$ivity, B-tu b ~ f -t"~ ( OF)-' Thermal expansion, i06/OC

8-315-A"

E-207-85"

L.85

S500 1.35-1.65

/CTZ~

Creep c o e f f i c i e n t a t 700째C, i n . in.-' psi-l nvt-l

Pemieabiii-ty t o h e i i m , cx2/sec

Dimensional irs%abili";yb a t 7OOOC

MSBR

1.80

lo5

%000

16-22

21-27

5.4-6 .O

4.G5.8

3.7-4.4-

8.9

Electrical resistivity, o:m-cm x 10A Isotropy f a c t o r , CTE

E-319"

x5 .o

9.9

1.11

1.20

8 x 10-2 1/2 t o 1/3 of AGOT

2 x

1.18

<10-

<1/2 or" AGOT

"G. B. Engle, The E f f e c t of F a s t Neutron I r r a d i a t i o n from 495OC t o 1035째C on Reactor Graphite, GA-6888 (Feb. 11, 19%). %ased or; very preliminaxy r e s u l t s or, 3-207-85and type 3 i s o t r o p i c &at&t o 2 X

lo22.

P P

111 damage. The f i r s t f a c t o r i s t h e r e c o g n i t i o n t h a t i n t h e 700째C temperature inVt do nothing more range, t h e dimensional changes f o r t h e f i r s t them r e p a i r t h e damage caused by cooling 0% t h e g r a p h i t e from i t s g r a p h i t i z a t i o n temperature. The a d d i t i o n a l dirriensional changes of t h e c r y s t a l s after nvt produce s.t;r.ess i n t h e g r a p h i t e i n t h e o:pposite d i r e c t i o n from t h a t produced by t h e thermal cooling. I n e f f e c t , the stress produced on t h e ba:;al planes w i l l be compressive i n s t e a d of t e n s i l e . This, of course, i s very much p r e f e r r e d i n t h a t t h e c-rystal. can s u s t a i n t h i s type of loedTng more r e a d i l y withoiit cracldng The a b i l i t y of g r a p h i t e t o s u s t a i n vexy l a r g e c r y s t a l shear;; i n t h i s manner has been demonstrated by i r r a d i a t i n g p y r o l y t i c carbons and observing shear s t r a i n s i n excess of 100% without my observable cracks i n t h e s t r u c t u r e . T h i s i n t e r n a l deformation was s o g r e a t t h a t i r r e g x l a r i t i e s were evi.dent on t h e suinface. Although t h e s e f a c t o r s do create optimism about t h e alxi.litjr of grfiphite t o s u s t a i n t h e i r r a d i a t i o n dose, experimental evidence i s needed t o deMOnStr2k t h i s a b i l i t y . a

E f f e c t s of I r r a d i a t i o n on IIasteI.l.oy N (1)t o cletermine t h e beThe o b j e c t i v e of t h i s prog-rat i s twofold: haT7ior of t h e LWRE s t r u c t u r a l m a t e r i a l s u m d m neutron i r r a d i a t i o n , and ( 2 ) t o i n v e s t i g a t e warri.ous ways ~f improving t h e r e s i s t a n c e t o r a d i a t i o n damage by making small changes i n chemistry. o r by s p e c i f i e d mechanical t r e a t m e n t s . I-Iastelloy N i s a complicated alloy, and w e do n o t have enough d.sta for" a s t a t i s t i c a l an.al.ysi.s; so some of our p r e s e n t i n t e r p r e t a t i o n s ~fiayseem c o n t r a d i c t o r y . Our f i n d i n g s are summarized below 1. The dependence of t h e creep-ruptru-e l i f e of Hastelloy N a t 650째C on t h e i n t e g r a t e d neut-ron f l u x i s sholm by the d a t a i n F i g . 4.13. These d a t a a r e f o r an air-melted lieat (5065) which was i r r a d i a t e d colcl.. The q u a n t i t y f i s t h e r a t i o of t h e r u p t u r e l i f e o f t h e i r r a d i z t e d mat e r i a l t o that of t h e u n i r r a d i a t e d material. There seem t o be a g e n e r a l t r e n d f o r t h e raLe of reduction i n r u p t u r e l i f e w i t h T l u x t o decrease as t h e s - t r e s s level. i s decreased. Three s l o p e s are i n d i c a t e d w k i c h a r e u s e d i n sibsequen-1; c a l c u l a t i o n s .

2. 'The r e s u l t s of t h e p o s t i r r a d i a t i o n c r e e p t e s t s of c o l d - i r r a d i a t e d specirnens were used t o p r e d i c t t h e c r e e p behavrior O S the a l l o y under siimdtaneous s t r e s s a r i d i r r a d i a t i o n . The b a s i c assumption 1nad.e i n t h i s treatment i s t h a t t h e creep-rupture curve i s not a l t e r e d by i r r a c i i a t i o n except t h a t t h e r u p t u r e l i f e i s reduced. I-Ience, one gives up a. s p e c i f i c f r a c t i o n of l i f e f o r an incrernent of f l u x . The l i n e s drawn i n Fig. 4.14 have equations of' t h e form

where f r

r u p t u r e l i f e of i r r a t l i s t e d mate?-ial. - -t r u p t u r e l i f e of u n i r r a d i a t e d material to

112 4, B = constan-is, 0 = i n t e g r a t e d thermal neutron f l u x .

To p r e d i c t what will happen when a spevimen i s sirnuI.taneous1y being s t r e s s e d and irradiated, Eq. (1)i s w r i t t e n a s

10’8 1 0j9 1020 THERMAL NEUTRON FLUX ( n v l )

Fig. 4.13.

Irradiation.

102’

Reduction i n R u p t u r e L i f e of Hastelloy N (Heat 5065) by

70 60

50 -

Q 0)

.0_

E LL

m 20

F i g , .4e14w Creep Rupture Properties of Rastel.l_oy N (Heat 5065) a t 650°C.

113 The c o n s t a n t s A and B a r e e v a l u a t e d from t h e s l o p e s of t h e l i n e s i n Fig. 4.13. With a value assigned t o t h e f l u x and a stress l e v e l chosen so t h a t t o i s lmown, it remains t o determine t h e va1iie of t t h a t s a t i s f i e s Fq. ( 2 ) . The procedure j u s t described w a s i i s e d t o c a l c u l a t e t h e l i n e s shown i n Fig. 4.14" The c o n s t a n t s obtained from t h e lower slope appear t o more cI.osely p r e d i c t t h e a c t u a l t e s t d a t a . P o i n t s a r e shown on Fig. 4.1.4 f o r two i n - p i l e c r e e p experiments. The agreement i s reasonably good a t s t r e s s e s above about 20,000 p s i , b u t t h e r e i s a d i s t i n c t t a i l i n g o f f xi; lower s t r e s s e s . 'This observation i s irtportant i n t h a t i.t i n d i c a t e s a longer r u p t u r e l i f e f o r s t r u c t u r a l m a t e r i a l s at t h e l o v s t r e s s e s i n -the KTRE t h a n w a s previ0us.l.y p r e d i c t e d on t h e b a s i s of a l i n e a r e x t r a p o l a t i o n . 3. The r e s u l t s of i n - p i l e c r e e p t e s t s and p o s t i r r a d i a t i o n creep 'Ibe d a t a from t e s t , OLpR 140 t e s t s a r e compared i n F i g s . 4.15 and 4.16. f o r h e a t 5085 (Fig. 4.2.5) seem t o show t h a t t h e r u p t u r e l i f e i n p o s t i r r a c E a t i o n t e s t s i s considerably longer .than t'ne l i f e i.n i n - p i l e t e s t s . The e f f e c t Lncreases w i t h decreasing s t r e s s . Data f o r two specimens a t 32,350 p s i i i i d i c a t e t h a t holding f o r s e v e r a l hundred hours a t 6-50"C and low stress a f t e r i r r a d i a t i o n r e s u l t i n u longer r u p t u r e l i f e a t high s t r e s s . The d a t a froi-n t e s t ORR 1.38 of specimens from h e a t 5065, shown i n Fig. 4.16, Pollow t h e sane p a t t e r n .

The specimens f o r t h e p o s t i r r a d i a t i o n t e s t s i n 0R.R 138 and 1-40were held. a.t 650째C f o r about 12013 hr under l i t t l e o r no stress during t h e i r r a d i a t i o n b e f o r e t e s t i n g . The i n - p i l e t e s t specirnens Were heated only & r i n g t h e t e s t . It seems p o s s i b l e t h a t .the d i f f e r e n c e i n thermal h i s t o r y

ORh

0 0

v, W

POSTIRRADIATION TEST A-IRRADIATED AT 650째C TO

*INDICATES SPECIMEN THAl WAS HELD A 10 -AND 15,000 psi FOR 667 hr BEFORE BEGINNING CREEP TFST A L L SPECIMENS ARE FROM TFST ORR-140

L ILLLLLII

1 ~

100

U w l 1000

TIME TO RUPTURE (hr)

F i g . 4.15. Comparison of I n - P i l e and P o s t i r r a d i a t i o n Creep Propert i e s of Ehstelloy 'I'J h e a t 5085) a t 6 5 O o C .

nwy

ORNL-DWG 66-4778

UNIRRADIATED

Ill

0 0

0 m

I 1

W E

I--

IN-PILE

EST

- ++h= 6x iOi3nv

-1I

POSTIRH4UIAI ION T E S l S 1 IRRADIATFD 1 FMP DOSE 8, 650 3 x 1020 0 - (50째C 5 x 10?O

0 U

5 x lo''

(5O0C

667 hr BEFORE BEGINNING CREEP 1000

100

10,000

TIME TO RUPTURE (hr)

F i g , 4.16. Comparison of I n - P i l e and P o s t i r r a d i a t i o n Creep Properties of Hastelloy N (Heals 5065) a t 650째C.

Table 4 . 3 ,

E f f e c t of I r r a d i a t i o n Temperature on t h e Creep-Rupture P r o p e r t i e s of Hasiclloy N Thermal. dose = 2.5 x

Spec i men Nuib er

Irradiation Ternperstin r?

("C)

&at, 5065

301 302 303 304

650 650 150 1.50

Stress (psi>

39 ,800

lo2'

Hupture

Life (hr)

14.8

nvi

Strain ikt e (%/hr1

Elongation

0 * 117 0.0034 0 "08 0 .O O L h

3 .4 1..37 5.5

($1

32,350 39 800

300.1

32,350

114.0

650 4-3

32,350

13.6 51.5

0.0137

0.28 3.4

650 650 150 150

39,800 32,350 39 ,800 32,350

2.6

0 -073 0.024 0. O w 0.0076

0.30 0.72 0.87 I.O

32 ,350

42 .O

3..25

Heat 7304

344 342 345 346

8.55 42.3

85 .it

115 might account; f o r a t l e a s t pal.-l; of t h e d i f f e r e n c e i n rupture l i f e . Thi.s suggestion i s par-Lly supported by r e s u l t s of o t h e r p o s t i : r r a d i a t i o n c r e e p t e s t s t h a t are included in Fig. l+.l6. Except a t &),oc)c) ps3. stress, t h e r u p t u r e l i v e s of specimens i r r a d i a t e d c o l d a r e general..ly l e s s than t h o s e of specimens i r r a d i a t e d hot; Al"ihougl.1 -tliere are not mmy d a t a f o r cornparison, t h e r u p t u r e l i v e s obtained by p o s t i r r a d i a t i o n tes'cs of t h e coldi r r a d i a t e d specimens are s h o r t e r than those of t h e i n - p i l e speclmens T'hr? thermal his.Lor.jr appears t o be an important factor. i n determining t h e c r e e p r u p t u r e E f e of i r r a d i a t e d Iiastelloy lil.

I n both creep-iuptu.re and. tensi1.c l x s t s , t h e p r o p e r t i e s of vacuum-melted h e a t c have shown a large rJ.epedence 011. the irrad-ia,tiori ternper-ature, whereas air-melted heats wcre less s e n s i t i v e .to i r r a d i a t i o n temperatui-e. '.Chis i s i l l u s t r a t e d by t h e da-La i n Table 4.3. 5ea.l; 5065 w,s a i r melted., nnd. its c r e e p properties show no co:ri.sistent rlepeiidence on i r r a d i a t i o n temperature. Heats 2477 a:ii.d 7304 were b o t h va.cu1~11 melted., and t h e r u p t u r e ].if? and d u - c t i l i t y were m u c h worse wliea -tile material was i r r a d i a t e d a t 650°C tiia-11w h e n i r r a d i a t e d a t 150°C. This e f f e c t i s prr:: sently .mnexpl.ained.

5. The effect oi" p r e t e s t h e a t t r e a t r w n t on 'ihe t e n s i l e p r o p e r t i e s i s sh.own i n T a b l e 4.4 f o r two h e a t s of l€astel.loy M. The range of heat t r e a t m e n t s w e d on h e a t 5065 had no detw-t;able e f f e c t on t h e d u c t i l i t j r It i s appa,reni; R srider range of heat; treatments ',Jars used. f o r h e a t 6 5 - 5 5 2 . t h a t the c1uctil.ity limprovecl. a:; t h e annealing temperature was i n c r e a s e d . %he g r a i n s i z e i n c r e a s e d considerably, and t h i s would. be expected i o i n cr:?ase t h e i r r a d i a t i o n e f f e c t s However., some o t h e r e f f e c t , possibly reanneal, moval of boron from t h e grain 'noundaries by t h e high-Lenipe'ature seems t o have been more impor-ta.ni;.

6. The effects of p o s t i r r a d ~ j - a t i o nariziealirig on t h e t e n s i l e psoperIV a r e shown by t h e d a t a i n Ta'ole 4.5- Annealing r e duces t h c ducl;il.ri.ty of t h e a i r - m e l t e d ht-.at 5065 by- about; a f a c t o r of 2. Tlie d u c t i l i t y of the vacuum melt, h e a t 65-552, is vlirtu.alJ.y imcha.ngt?d by annealing up t o above 871°C. l h e a l i n g xl; 1.200°C i n c r e a s e s t h e dlu.ctility i;%es of H a s t e l l o y

by about a fac-Lor of 3.

Weld S t u d i e s on X a s t e l l o y

The weld skudies on Has-tellojr N have two general. o b j e c t i v e s : (1) t o improve t h e w e l d a b i l i t y s o t h a t welds have g r e a t e r s t r e n g t h and duct i l . i t y , snd ( 2 ) t o study t ; ? ~e f f e c t s of i r r a d i a t i o n on the pro:perties of welds and i n v e s t i g a t e ways of irniproving t h e i r r e s i s t a n c e t o i r r a d i a t i o n damage. It was reported. previously1* t h a t w e l d s i n v o l v i n g o t a n d a r d a i r m e l t e d heats of IIastelloy N e y h i b i t e d lower r u p t u r e l i f e and. d u c t i l i t y a t 650°C, as compared with t h e base m e t a l s . EIowever, t h e p r o p e r t i e s eou7.d be recovered by postweld annealling. . It w~tsalso shown t h a t welds i n Electron vo l v i n g vacuwn-me It e (I r.ria-t;er i a l s exiiib i t e d. b e t te r pr ope r t ie 6 microprobe s t u d i e s have since shown t h a t s i g n i f i c a n t s i l i c o n segregation occurs i n t h e weld me-tal.. These observation:; have :Lead t o t h e proposal. c

Table 4.4. Effec5 of P z e t e s t Annealing on t h e Tensile P r o p e r t i e s of Hastelloy N -1 )'

(6530~0 , . ~ 0 2i n . ic.-l air,

Experiment

a 'u t 3

'Uniform

Total

Ave I-age Grain Size (im)

Yield Strength

Elorigetiori

Re due tion i n Area

(Psi)

(%)

Elongation

BTone n'one 8 hr a t 871째C

0.05 0.05 0.05

40,000

11.4 12.2 3.7

11.6 13.1 14.3

17.5 2i.9 17' 3

1Ton.e

C .025

47,8CQ

5.1 4.7 6.6

5.3 4.9 6.7

kmeal

None 8 hr 1 hr 1 hr 1 hr

a t 871째C at 1177째C z< 1177째C a.t 1316'C

0.025 0 .a5 0.10

Cl.rC. 0.2:

40,80f; 38, IC0

47,500

41,200 37,600

48,400 46,200

14.4

15.5 21.8

(%I

14.5 15 .ET

23.3

13.9 7.10

15 .O 16.1 2G .7 40 .3

117 Table 4.5.

E f f e c t of P o s t i r r a d i a t i o n " knneali.ng on t h e T e n s i l e P r o p e r t i e s of' I l a s t e l l o y N (65OoC, 9.002 i n . in.-'

Postirradiation Anneal

mill-')

Yield S-Lrength (psi)

Uniform Elongation

Total Elongatiori

40,800

46 300

22.8 12.2

24.0

28.1

43,900

10.9 6 .cj

11.5 12.4 6.7

15.5

41,600

22 .0

22.A

($1

Reduction i n Area

($ 1

($1

Heat 5065 Control None 400°C f o r 1 h r 650°C for 1 l1r 871."C f o r 1 br 1200°C for 1 h r

41,900 42,100

37,200

%1..9

W.l

11.0

7.0

16.3

10.7

7.5

12.5

? k a t 65-552

Cont r o 1 Hone 4.00"C f o r 1 h r 650°C f o r 1 hr

4.r,', ,500 151,100

1200°C f o r 1 h r

38,800

871°C for 1 h r

46,1.00 43,000

a. k r a d i a t i o n temperature = 4 3 O c ;

"th

2.3.5 7.10 1.3.6

4.9

4.7 1, 1 3.6 3.3 12. 7'

Lk..?;.

5 .El 3.7

10.3,

8.82 18.o

12.8 =

3.5 x

lo2'

nvt

t h a t s i l i c o n may be r e s p o n s i b l e f o r t h e poor weld.a'oility of Hastelloy N, and s t u d i e s have been d i r e c t e d toward e s t a b l i s h i n g t h i s point inore firmly. I r r a d i a t i o n damage s t u d i e s have involve d determining how i r r a d i a t i o n changes t h e t e n s i l e p r o p e r t i e s . Based on t h e premise that a l a r g e grain s i z e i n t h e weld metal may cause degradation of t h e p r o p e r t i e s -under irr a d i a t i o n , attempts have been made to recluce t h e g r a i n s i z e by adding ra n--ain-refining i m p u r i t i e s t o -I;lie f i l l e r nietal. Tlie work i n b o t h of t h e s e areas i s presented b r i e f l y . S e v e r a l experimental welds were made t o study t h e e f ' f e c t of s i l i c o n on t h e p r o p e r t i e s of the weld metal. A s i n g l e J-groove j o i n t configura.tion with an included angle of 50" was s e l e c t e d . A second group ol" experimental. welds was made i n an e f f o r t t o r e f i n e the weld-metal g r a i n s i z e and/or provide innocuous p r e c i p i t a t e s upon which t h e helium ( f r o m t h e n,CX r e a c t i o n ) molecules can assimilate. Experimentally, this has been done by spray c o a t i n g an air-melted. Eastel.l.oy N f i l l e r m e t a l ( h e a t 5055) with A1203. The weld made from t h i s f i l l e r m e t a l was designated No. 7. For comparative purposes, weld N o . 4 vas made w i t h unsprayed, air-melted f i l l e r m e t a l T r o m h e a t 51.01; weld No. 6

118 w a s made w i t h a vacuum-me7.ted f i l l . e r m e t a l ( h e a t 65-552). The compositiGils of t h e i-ndividual f i l l e r metals are given i n Tah1.e 4 . 6 . 'The compositions of t h e base m e t a l and t h e deposited weld metal f o r welds 6 a n d . 7 are also given i n Tab1.e 4.6. A s can be noted i n Table 4.6, most of the A1203 (weld metal. No. 7)w a s l o s t as a s l a g during welding.

The creep-rupture p r o p e r t i e s of welds 4 , 6, and 7 are compared i n Fig. 4.17 wi.Lh those of t h e ba,s? metal. and weld No. 1 (duplicaLe of weld No. 4 ) The p r o p e r t i e s of weld No. 4 were q u i t e cl.ose t o t h o s e previously observed f o r weld No. 1. Using weld No. 4 as a base l i n e , weld. No. 6 w a s s l i g h t l y weaker, and weld No. 7 w a s s l i . g h t l y s t r o n g e r . The r u p t u r e elongations a t a s t r e s s of 40,000 p s i were 3 , 6, and 3% for we1.d Nos. 4 , 6, and 7 r e s p e c t i v e l y . A3.1 f a i l u r e s were observed t o occu.r i n e i t h e r t h e weld metal. o r a t -the f u s i o n l i n e . Mei;a.ll.ographic s t u d i e s are i n progress t o determine t h e exact l o c a t i o n of t h e f a i l u r e s .

S e v e r a l of t h e specimens were heat t r e a t e d a f t e r welding for 8 hr a t 871째C. A s shown 5.n Fig. 4.1.7, t h i s treatment produced a s i g n i f i c a n t improvement i n the c r e e p s t r e n g t h ; the d u c t i l i t y w a s a l s o improved. A comparison i s made i n Tab1.e 4.7 of t h e degree of improvement caused i n t h e d i f f e r e n t welds by- pos.tweld h e a t t r e a t i n g . 'The h e a t treatment made t h e r u p t u r e l i v e s of t h e welds more n e a r l y t h e same and e q u a l -to or b e t t e r t h a n t h a t of the oi-iginal- base m e t a l . .

ORML-DWG 66-4779

a 0

m w

. . .-

100

10,000

F i g . 4*17. Compar-ison of t h e Creep-Rupture Properhies of Welds and Base Metal.

v a, s aJ d w

-?l 0

119

U '

c'\ 0 0 0 a 0 0 0 0 0 0

120

Table (+.7. Effect of Stress-Relieving on .the Creep-Rupture P r o p e r t i e s of Hastelloy N (65OoC,

40,000 p s i )

-.-

__I_.-

(hr1

Stress - R e l i e v e d Rupture Life (hr1

Ratio, S t r c s s-Relieved

300 t o 550

420

1 2 to 22

A s -We 1ded Rupture Life

No.

_....

to AS-WF:.l.dCd

.._

7.8

370

___

._.....

-r 1 I

ORNL-DWIG 66-1877

t A

1RRll:AltU

MClAL

BASE

WELD SPECIMENS

IRRADIATION T F M P E R A T U R E

-z 50

CONTROL

ii?

;I 30

0 TEST

I E M P E R A T U R E ("C)

Fig. 4.18- Comparison of t h e Ef'fects 02 I r r a d i a t i o n on the l ' e n s i l e Pro-geyties of Welds and Base Me'cal.

121 Since only a few of t h e i r r a d i a t e d specimens from welds 4 , 6, and 7 have been t e s t e d , it i s necessary t o speak i n g e n e r a l i t i e s concerning t h e p r o p e r t i e s of t h e s e welds a f t e r i r r a d i a t i o n . Specimens of a l l t h r e e welds :.rem i r r a d i a t e d i n t h e ORR a t 43째C t o a thermal neutron dose of 8.5 X lo2' n v t . F i g x - e 4.18 compares t h e t e n s i l e e l o n g a t i o n of t h e base m e t a l and weld No. 4 specimen before and a f t e r i r r a d i a t i o n . I n general, t h e base metal i s a f f e c t e d t h e most. 'Ike welds i n i t i a l l y have lower d u c t i l i t y , b u t t h e d u c t i l i t y i s not reduced much by i r r a d i a t i o n . A t a t e s t temperat u r e of 871째C, t h e weld and t h e base m e t a l have t h e same d u c t i l i t y . A t a s t r a i n r a t e of 0.002 i n . in.-' min-' and a t e s t temperature of 6 5 O o C , t h e t o t a l e l o n g a t i o n s of we1.d~ 4 , 6 , and 7 were 5.2, 7.0, arid 6.4% respeet i v e l y . Thus, it seems t h a t t h e doped weld wire had little, i f any, e f f e c t on t h e r u p t u r e d u c t i l i t y . Although postweld h e a t treatment irnproved t h e u n i r r a d i a t e d d u c t i l i t y , it vas found t h a t t h e d u c t i l i t i e s of t h e aswelded and postweld h e a t - t r e a t e d m a t e r i a l s were comparable a f t e r i r r a d i a t i o n . A l l t h e i r r a d i a t e d specimens f a i l e d i n t h e weld metal. These same welds w i l l be evaluated f u r t h e r through p o s t i r r a d i a t i o n creep t e s t ing.

References

1. G . M. Adamson, Jr., e t a l . I n t e r i m Report on Corrosion by Zirconium Rase Fluorides, ORNL-2338 (Jan. 3, 1961). 2.

P4SR P r o g r m Semiann. Progrr. Rept. Aug. 31, 1965, 0RNL3872, pp. 81-

87.

3. 4

MSR Program Semiann. Progr. Hept. Fc'Q. 28, 1965, ORtTI,-3812, p. 8 5 .

PE.R Progran Semiann. Progr. Rept. Aug. 31, 1965, ORIIL-3872,

p . 90.

NTR Program Semiam. Progr. Bept. J u l y 31, 1964, 0BN3,-3708,

pp.

E. J. Manthos, Metals and Ceramics Div. Ann. Progr. P k p t . June 30, 1965, OXNL-3fi70, P,O. 251-55.

281-86.

8. J. IT. W. Simaons

and

A. J. Perks, NaturP 206, 610 (1965).

9. PER Program Semiam. Progr. Rept. Aug. 31, 1965, ORNL-3872, 10. I b i d . , p. 9 4 .

p. 93.

122

Chemistrv of t h e MSRE Amlyses of t h e Flush, Fuel, and Cool.ant S a l t s

It i.s impor-Lant i n mol-ten-salt reac-Lor operations t o be able to a s c e r t a i n qu.i.ckly and a c c u r a t e l y that, t‘ne uranium concentration i n t h e molten f i e 1 s o l u t i o n conf‘o-ms t o design s p e c i f i c a t t o n s and t h a t chemj-cal p u r i t y of t h e s a l t i s maintained. S i g n i f i c a n t advan i.n a n a l y t i c a l metnods have been incorporated i n t o r o u t i n e p r a c t i c e since tine zero-power experiment w a s coniple.l;ad i n J u l y 1965. The increased accuracy which i s apparent i n chemical. analyses shows more c l e a r l y t h a n e v e r t h a t composikion and p u r i t y of t h e r e a c t o r salts can be a s c e r t a i n e d accu.rate1.y and economically on a r o u t i n e b a s i s and that, c u r r e n t methods now a f f o r d e x c e l l e n t monitoring p r a c t i c e s t o molten- s a l t technology. Application of t h r e e i.nnovations to tile ana1.ysi.s of MSKE s a l t s has been made w i t h i n t h e c u r r e n t r e p o r t period: a new end p o i n t f o r ura,iiium t i t r a t i o n s , a new method f o r s t r u c t u r a l - m e t a l i o n s , an4 a new method f o r oxide analyses. Together, they have provid.ed i n c r e a s e d assurance t h a t t h e composiLrion of t h e Fuel conforms Lo t h e inventory values and r e a c t i v i t y balances and -Lha’i t h e chemical p u r i t y of Lhe s a l t i s even grea’Ler t h a n could. be affirmed from prevli-ous r e s u l t s . Uranium Assay-. C o n t r o l l e d - p o t e n t i a l coul-ometry i s used as t h e primary meLkiod f o r determj-nation of uranium i n MSE fbe1. because of t h e high order of precision. i n h e r e n t i.n t h e mnethod.’- From 50 t o 100 iJ-g of uranium can be t i t r a i ; e d w i t h a preci.sion o f t h e order of l e s s than 1%.

Evidence was noted during t h e p r e c r i t i c a l and zero-power e x p e r i ments t h a t a d i - s t i n c t b i a s be-Lweeli aomrina1. and a n a l y t i c a l . valu.er, f o r uranium e x i s t e d and that, t h e a n a l y t i c a l valuer f o r ura.arium were approximately 1% lower t h a n nominal. We 7-nferred t h i s phenomenon t o be a consequence of d i l u t i o n of t h e f u e l s a l t by f l u s h s a l t , although -the amount of d i l u t i o n reqiii.red. t o r a t i o n a l i z e t h e b i a s was o f t h e order of 1-40l b , somewhat higher t h a n w a s compatib1.e with t h e weigh-cel.1. d a t a .

A recent refinement i n t h e method of de-temai-nring t h e uranium end p o i n t - i n t h e contro7.7.ed.-potential coulometric a n a l y s i s has been made. “he end p o i n t had previously been estimated. as t h a t poini; a t which tile e l e c t r o d e c u r r e n t i s reduced t o 5 wa. The en.d.-point values are now computed by e x t r a p o l a t i o n of t h e redi*ction-poteni;rial curves t o zero f r o m a 50-pa c u t o f f p o i n t . I n recent c o n t r o l analyses i n which s y n t h e t i c standards were u-sed, t h e 5-pa end p o i n t wan demonstrated t o have a negative b i a s of 0.6, whereas t h e b i a s f o r t h e 50-113. e x t r a p o l a t i o n end p o i n t war; zero.

Book value f o r t h e ui-ani.ill-n concentration of LIE f u e l s a l t which i s c u r r e n t l y c l r c u l a t e d i n t h e MSRE i s 4*646 w t The mean an.aly-tical value i s 4.642 0.026 w t $. Thus t h e improveiiient in t h e method of

123 computing the uranium end p o i n t has reduced t h e bias 'oetweerz inveatoqr a i d a n a . l y t i c a l values t o minch less t h a n onr. s-tandard d e v i a t i o n of t h e a,!zal.ytlcal method. Uranium I s o t o p i c A-nalysis of t h e MSIa k ? u e l . m e co'mposi"li-on of t'ne circula1;ed and s t a t i c f u e l s a l t s i n t h e MSRF beeme coinpositionally homogeneoias f o r t h e f i r s t tinie a f t e r c0q112tiori of the zero-power exprimexit;. 'fie 2 3 5 ~enriclunerit f r a c t i o n of ti?e s a l t c i r c u l a t i n g a t z ~ ~ r o power was found experimentally -to be 33.7.1. 1st; $, a s conipared with t h e book value of 33.5 8 . A f t e r circul.stiorr, t h e salt im:; d:r*airied into t h e storage tanks, blending t h e r e with o t h e r fuel of l o v e r "5UF/, COILc e n t r a t i o n . No s i g n i f i c a n t bumup has, as y e t , occinred. i n the fuel* We h a m had, t h e r e f o r e , an opportunity a t t h e beginnin.g of t'ne fl1.1.1.pc"v;ier experiment t o e s t a b l i s h an anal.y'cica1 b ~ s el i n e of' enriehmenit. %IE e x p r i m e n t a l renii1ts show t h a t t h e r u e 1 now contains 2 3 5 ~a t 33.2~~1 wi; $ > i n good agreenien-t; with a c a ~ c u l a - t e dvalue of 3 2 . 2 TJ-L $.

.,,

Strvc-t;ural-Metal I m p u r i t i e s . We have i n f e r r e d thzt; n i c k e l i.s p r e s e n t 1x1 t h e MSZB Puel s a l t orlly as a. m e t a l l i c phase and tiriat i r o n i.s a l s o present, predominantly, f . f not enLirely, i n nie1;all.i~ Yorm. I n an atteeuipt t o gain evi.dence :;o support thi.s i n f e r e n c e , sis;rrp?les of the s t a t i c f i e 1 s a l t were obLained fraii. the fl-iel storage ta.nlts iluring t h e two-week period. f o l l ~ w i r i gt h e ZeZ*O--Po%7e1. experj.ment. 'I%ef a c t t h a t -LIE concentrations of t h e s t r u c t u r a l - m e t a l i r n : p u r . i t i c l ~ s were no-t found t o change during t h i s storage period l e d . us to conclude tlm, thermal convection in Lhe s-Lorage t a n k was adeq~ta-Lct o prevent s e t t l i n g of Pine rneta1.lj.c par-Llcles of t r o n and n i c k e l i n the clrain tank.

I n recent experiments a sm:ple of t h e MSIZ fuel m i . s removed from t h e pump bowl before s i g n i f i c a n t power. was generated by -the reactor; t b i s simple wa6 analyzed. By 8 nevly developed method using c o r k r o l l e d potential voltmrm1et:c-y. 4 TIE s a l t w a s found t o c o n t a i n approximately 8 t o 10 ppm of .iron i n t h e d-ivalezit s t a t e . 'L3-e concentration of n i c k l o u s i o n w z ~ sTound. t o be l o w e r Ynan 5,:; detectable by- t h i s method, tha-1; i s , less t h a n 1 ppm. The net coricentrati.ons of i r o n arid nick,el. in t h e s a l t specirrieris were 1.31 and 40 ppm r e s p e c t i v e l y . The sa1.t a . l s o con-tains 48 ppm of chrorn-im- I n i o n i c form. These r e s u l t s a r e p a r t i c u l a r l y ur,e.ful i n that, t h e y i n d i c a t e t h a t t h e t o t a l concentration of io:nFr: s t r u c t u r a l - m e t a l conta;miriaxt,s i n t h e f i e 1 i s not greater. than 58 ppm.

Oxide Analysis. Mos-t; serious of' the adverse consequences of chemScal i m p u r i t i e s i n MSSE m e those which would arise from cont,miinatFon 'oy oxides. O f g r e a t sigriificanee i s t h a t oxide content of' t h e MSâ&#x201A;ŹB s a l t s can nov be determined r o u t i n e l y and a c c u r a t e l y zrt; concenbratj-ons lower t h a n 100 ppiii by purging samples of t h e rrrolten salt with 11% arid HF. Oxide concentration 5.s t h e n c a l c u l a t e d from the m o u n t of w a t e r recovered froin the effl.uent gas stream. !!%is hydrofluori.nation method f o r dete-mmining t h e coricentration of oxides i n molten f l u o r i d e s wus applied t o a n a l y s i s of t h e MSRE f l u s h , f u e l , and c o o l a n t sal-ts f o r t h e f i r s t time a.t the beg51ming of the -ful.l-po-vrer e x p e r h e n t . A t t h a t p o i n t t h e r a d i o a c t i v i t y of t h e salts w a s n e g l i g i b l y low, and. anzlyses could be performed i n t h e development l a b o r a t o r y . At; a c t i v t t y was generated i n t h e me1 s a l t , it became imperatiTse t h a t subsequent cheiilical L

12A

analyses be conducted i i l t h e Bigh-Radiation-Level. Analytical F a c i l i - t y (HIUAP). Currently, apparat,us d i i c h ri.s t o be used f o r r o u t i n e ana1ysi.s of t h e oxide concentration of MSRE s a l t s i s beiag i n s t a l - l e d and. t e s t e d i n t h i s facilrity. The r e s u l - i s of t h e analyses performed t o d a t e i n t h e developinmi; l a b o r a t o r y r e v e a l t h a t tile oxide concentration i n t h e MS3E f l u s h , f u e l , and coolant s a l t s i s 75, 95, and 40 ppin r e s p e c t i v e l y . On t h e b a s i s ot t h e r e s u l t s ob'iaj-ned by Jhes and. c o - ~ o r k e r s , s~a t u r a t i o n of t h e f i e 1 by oxide i s considered t o occur ai; approximately 500 ppm a t t h e r e a c t o r opera-tiiig 'cemperature of 1200"F;. The currenJL a a a l y - t i c a l d a t a 5.-ndicate, t h e r e f o r e , thai; t h e MSM s a l t s , which have remained. i n tlne molten s t a t e f o r some teii months, have been well protected. from moi-sture contzmLilat i o n during t h i s per-iod.. S a l t Compositj.on Analyses. 'Yhe sampliizg schedule which w a s followed a t tile beginning oi'"%lie MSM f'L1.l-power experiment afrorded t h e f i r s t oppor.tiiuity to o b t a i n stati.stica7.ly meani-ngf'ul analytlical d a t a . The r e s u l t s of a11 chemical a,nalyses of t h e MSW, s a l t s which have beeii p e r formed i n connection with the full-power experiments a r e given i n Table 5.1. The cornpositri.on o f t h e fuel s a l t , as i n d i c a t e d by t h e s e d a t a , i s compared. tn Table 5 . 2 with t h e r e s u l t s of previous analyses. li; i.s apparent from tliesc d a t a t h a t , but f o t~h e sti1.l unexplained minor b.i.as between nominal and analyLlcal values f o r l i t h i u m and beryllium, t h e agreemeni; between inventoiy records and a n a l y t i c a l r e s u l t s i s excellent. Exaaination of Materri-als from t h e MSEB Off-Gas .......... ._.. ....System . 'The program f o r bringring t h e MSRFl -Lo fii-11-power o p e r a t i o n has been i n t e r r u p t e d on t w o rece-nt occasfons by flow r e s t r i c t i o n s i.n t h e o f f - g a s system. Symptoms of plugging became pronounced. i n each case a f t e r about 1 2 h r of o p e r a t i o n a t 1 Mw. Small specimens of t h e m a t e r i a l s which were siispzcted t o have caused pl.ugging vere removed from t h e a f f e c t e d par-Ls of the o f f - g a s system and subijec-ted. t o various 'iests i n an attempt t o determine tile reasoiis f o r flow r e s t r i c t i o n s . I - L w a s assumed. t h a t chemical i d e n t i f i c a t i o n would i n d i c a t e t h e cause of t h e restrictions. R e s t r i c t i o n s were f i r s t noted i n 'die c a p i l l a r y r e s t r i . c t o r i n l i n e 521; at; -the same time the 513 check valvz became i n o p e r a t i v e . R e s t r i c tion w a s a l s o noted i n t h e s i n t e r e d stainless s t e e l l i i l e filter and 522 valve assembl-age. I n o r d e r t o resume operation of t h e r e a c t o r , t h e capi1lar.y r e s t r i c t o r and 533 check val.ve were replaced by n o n r e s t r i c filter t i v e s e c t i o n s , and t h e f i l - t e r - v a l v e assembly w a s replaced. element, which was removed was capable o.P blocking passage of more t h a n 9 q 0 of t h e p a r - t i c u l a t e m a t t e r of 0.7 1-1 i n diameter. It w a s replaced by a f i l t e r designed t o b l o c k p a r t i c u l a t e s of >50 IJ- i n diameter. On resuming o p e r a t i o n a t 1 Mw, r e s t r i c t i o n s appeared t o develop ri.n t h r e e l o c a t i o n s : a t valve 522B, a t t h e en-Li-ies t o charcoal beds 1A and lB, and i n t h e l i n e s ahead of t h e a u x i . l i a q - charcoal bed. Currently, a specimen bas been obtained only f r o m valve 621, whtch con'iro1.s flow i n t o charcoal. bed 1.B. ExamFnations and t c s t s a r e s t i l l being perfomed.

Table 5.1. Sample

Circulation

Number

Period (hr)

Summary of MSRE F l u s h a n d Fuel Salt Analyses, Full-Power E x p e r i m e n t

Concentration (wt %) L1

Concentrahon (ppm)

104.02

110

<10

Flush Salt

FP4-1 FP4-2 FP4-3

13 19

13.65

9.83

<0.0025

0.0210

80.52

25 <0.0025

0.0207

79.34

102.26

212

FP44 FP4-5

FP4-6

13.50

9.96

<0.0025

0.0200

80.07

103.55

125

FP4-7

13.65

9.46

<0.0025

0.0241

77.85

100.98

180

FP48

FP4-9

13.35

9.98

<0.0025

0.0221

75.80

99.15

210

FP4-10

13.55

9.4s

<0.0025

0.0230

75.05

98.11

128

FP4-11

FP4-12

FP4-13

FP4-14

27 31

FP415

FP4-16e FP4-17

FP4-18 FP4-19* FP4.20f

13.55

9.35

(15

<I5

6.33

10.52

(20

<15

7 80

<20

<15

150

<20

<15

<20

<I5

106 '

4.673

66.45

142

1300d 120

98.42

<I5

144 105

10.20

6.41

10.77

4.634

64.67

96.68

<15

92 80

48 53 64 68

74 72

<10

Fuel Salt 30.45

56 46

65 10.25

6.68

11.24

6.40

10. a2

4.671

6.54 5.74

i0.95

54.68

97.37

116

65.06

97.57

35 45

FP4-21

75 99

10.47

FP4-22

124

10.54

FP4-23

143

10.27

4.651

67.44

100.26

144

66.79

99.15

121

<15

<I5 <15 <I5

FP424

172

10.65

6.55

10.96

4.664 4.642 4.655

67.66

100.58

116

PP4-25

199

10.60

6.37

11.41

4.646

65.44

98.47

<15

FP4-26

217

10.60

6.63

11.20

4.642

66,90

245

10.55

6.53

11.07

4.618

67.68

222

FP4-28

268

10.60

11.10

4.663

66.19

98.97

FP4-29

314

10.70

6.42 6.71

50 49

4; 41

<15

FP4-27

99.97 100.45

11.54 11.19 11.26

4.654

69.75

103.35

<15 <I5

4.661

57.32

100.58

4.632

68.51

101.33

FP4-30

362

10.63

6.81

FP4-31

435

10.30

6.63

10.86

211 111 83 190

35,

49 37

<I5

Table 5.1 Sample Phumbes

Circulation Period (hr)

Concent:ation L:

(continued)

(w: 70)

Concentration (Pam) Fe

FP4-32

457

10.55

6.71

11.80

4.625

67.66

101.34

173

FP4-33

529

11.209

6.75

11.07

4.596

66.25

99.97

FP4-34

60 I

11.35‘

6.49

11.13

4.601

68.20

101.82

164

FP4-35

559

11.36g

6.68

10.86

4.721

69.35

103.01

11.25‘

6.32

l1.20

4.632

56.76

100.16

125

<5 <5

6.33

11.08

4.622

69.35

132.63

189

100.56

31 1

E0 25 40

110

FP4-36

1:.30E

F34-37 FP4-38

10.65

6.54

11.46

4.608

67.25

FP4-39

10.60

6.33

11.54

4.619

68.33

IO 1. J+2

Coolant Salt

CP4-1

CP4-2

CP4-3

CP4-4

CP4-5

180

CP4-6

194

C35-1

236

CP5-2

99.39

41 53

<0*002

76.80

99.87

8.85

<0.002

76.7

99.41

(10

150

8.55

<0.002

76.6

99.07

(10

110

8.91

14.20

8.87

13.86 13.82

aValues corrected to 33.241 w t % 235U. bHF-purge method. ‘KErF,

130 185

76.70

13.78

method.

dSarnple exposed to dry-box atmosphere f o r r 8 hr. W o sample ootaineci.

‘For arqperometric ana1ys:s.

gErroneously hlghh; at:ribu:ed t o Palling batteries in a h t o x a f i c pipette.

. .

c ; d o o +I

. .

--i:oâ&#x20AC;&#x2122;lno a cu

127

D m 0 0

1.28 with the a v a i l a b l e specimens.

Resul-ts a r e summarized i n Table 5.3.

On t h e b a s i s of t h e r e s u l t s shown i n Table 5.3, we wo1il.d concl.ude t e n t a t i v e l y t h a t t h e r e s t r i c t i o n s i f 1 t h e o f f - g a s l i n e may be a t t r i b u t e d t o v a r n i s h - l i k e organic m a t e r i a l . Gulfspri.n-.35 i s used a s the 1uhricaLi n g o i l f o r t h e r o t a r y element. 1-'6i s cornposed p r i m a r i l y of a mixture of lonti;--chain a l i p h a t i c J-inear and brainched h-yd.i?ocas'oons. Recent measurements show t h a t i t s r e f r a c t i v e index i s 1.473. The ref-ractive index of -the h e a v i e s t l$ volume f r a c t i o n obtained on vacuum d i s t i l l a t i o n of the o i l was found t o be approximately 1.50. The high r e f r a c t l v e index of t h e v a r n i s h - l i k e mater.i.aIs removed from t h e o f f - g a s system suggests t h a t radi.atj.on polymerization has produced t h e pl.ugging phases. This Ln-ference appears t o be strengthened f u r t h e r by t h e observation t h a t the varnish-J.j.ke m a t e r i a l s appeared t o have lLmited o r no s o l u b i l i t y a'i room temperature i n xylene, pe-troleum etiier, carbon te-trachlorlide, or acekone I

Uraniim-Pearing....,C ..-q y s i a , l n i n Frozen Fuel X-ray d l f f r a c t i o n s t u d i e s o f uranium-bearing sa3:Ls from s o l j d i f i - e d MSRIZ fie]. and/or- concentrate have y i e l d e d informati-on of chemical i n t e r e s t . A complete c r y s t a l s-tructure anal.ysis of "'TLiF' GUFq" hac shown t h i s t e t r a g o i i a l subs-Lance ac-tualby t o he LiUF5 and to have a b a s f c a l l y d . i f f e r e n t s t r u c t u r e from t h e rhombohed.ra1. co:nipounds which do have t h e 7:6 r a t i o . Compounds of the l a t - t e r s t o i c h i c n c t r y do not appear i n the p r e s e n t f u e l mixtures. I n LiUE'5, each U4'+ i o n i s coordinated by nine P' i o n s i n t h e shape of a t r i g o n a l prism ~ - L each h r e c t a n g u l a r face bearing a pyram-id. T h i s polyhed.ron i s s i m i l a r t o those i n U2F5, b u t d i - f f e r e n t from those oi" 8-coordinated " 'U ri.n UFk. It i s not p r e s e n t l y k:irtown whether 'chis d - i f - ference i s signi.fica.nt o r j u s t a coincidence of packtng of F i o n s .

A determination of the s t r u c t u r e of Li.,+UF8 i s par-Lia1ly coffiple.l;ed: t h e orthorhombic c r y s t a l s have u n i t - c e l l dimensions a :: 3.96 A, b = 9.88 A, c = 5.99 A, and t h e space group i s Pima o s 1%a21. Four formula weights of Li&UE'8 5.n a u n i t c e l l comespond t o a c a l c u l a t e d dens3.t-y of 4.71 g/cm3. The p o s i t i o n s of IT4+ i o n s have been determined, but t h e o t h e r i o n s a r e y e t t o be l o c a t e d .

Phvsical Chemj-strv of Fluoride Mzl-ts

~_Vapor Pre s s w e of Fll.iioride Melts Apparatus was constructed t o o b t a i n vapor p r e s s u r e s by -tile c a r r i e r gas method. i n order t o determine (I~) vapor composition i n t h e LiF-P?Fz system ( t o complene-at, t h e manometric pressui-e d a t a already obtained f o r t h i s system7), and ( 2 ) r a r e - e a r t h vapor concentrations i n equ.i.librlum wlth l i q g l d . mix-Lures of impor'iance t o Lhe m o l t e n - s a l t r e a c t o r disti1l.at i o n procecs (from t h e s e concentrations more accurate decontamination f a c t o r s f o r t h e r a r e - e a r t h f i s s i o i i products will^ be o b t a i n e d ) . The apparatus, shown schematically i n Fig. 5.1, c l o s e l y resem'oles &.,8 f o r s t u d i e s of -fluoride r:iel.Ls. The relLabili-Ly

t h a t used by Sense

-st

129 Table 5.3.

Results of Examinations o f Specimens Removed from t h e MSRE Off-Gos Lines

Specimen Description and Origin

Morphology

Refractive Index

Isotropic particles, appearing a s partly coalesced amber globules

1.520

2. Scrapings from spool piece adjacent to capillary

Same a s 1

1.540

3. Deposit from check

Isotropic, amber, varnish-like particle, -50 )I

1. Deposit from exit orifice of

capillary restrictor

valve 533

at Contact (r/hr)

Activity

Predominant Isotopes (from gamma scan)

p ~ g ;Be, 121 pg; Zr, 100 \rg

Li, 99

Be, 0.95 pg; Li, 2 p g ; Zr, <0.5 Pg

100 p

Scrapings from valve 522 poppet

5. Scrapings from valve 522 seat

Isotropic, amber, varnish-like matrix containing embedded isotropic( ?) crystalline material of lower refractive index Same a s 4

6. Oil drops from 522 valve

'"1.540

1.544 to 1.550 1.509

Scrapings from stainless steel filter element

8. Metallic scrappings from

stainless steel filter element

9. Deposit from IIV 621 valve stem

2.5

No Zr, Nb, Ce

1.5

RgSr,

I40

Ea,

No Zr, Nb,

body 7.

Isotropic, faintly colored material, more nearly scale-like than glassy i n appearance

1.524 to 1.526

l4OB8,140La,

'03Ru,

1 3 7 ~ s no ; Ce, Zr, Nb

Granular opaque particles; low index, transparent, birefringent crystalline material spalled off metal on microscope slide Isotropic, faintly

colored material.

varnish-like in appearance with pebbly surface

Spectrochemical Data

-1.526

I3'Te

1.39 MOLECULAR SIEVE DRYlNG COLUMN

PRESSURE GAGF ( 0 - l o i n H 2 0 )

THFRMOCOUPLE NO 3 - ,

I NG C0LUMN;THEN ON TO WET TEST METER

'-CONDENSER TUBE (CONDENSER H A S 0 0 3 1 - 1 n OPENING IN END AEOVE CENTER OF SAMPILE B O A T )

F i g . 5 .l. T r a n s p i r a t i o n Apparatus.

of -Lhc apparatus and t h e e f f i c a c y of t h e washing procedures f o r rL "rrmvi n g condensed vapor. were "ies t e d . wi.tln pure LiF. Satisfactori-y agreement with the relri-able t r a n s p i r a t i o n . d a t a obtainecl by Sense' was a t t a i n e d . Three compositions of tile Li.F-XkF2 system have -illus Tar been invec.t?'.gated.. The vapor-pressure da.i;a are suima:rri.zed in Table 5. 4J based on the asswnpkion t h a t "ne vapor consists only of monomeric LiF and. b F 2 . It should be no-tcd -that the appai-ent .... ......- p a r t i a l p r e s s u r e of LiF i n c r e a s e s with decreasing concentration of' LiF i n t h e me1.t. T h i s hehavr*.ola i.s c o n s i s t e n t with t h e e x p e c t a t i o n t h a t L h c . vapor spec-ies i.s predominantly a cornpou.nd of LiF arid &E'?, such as JJi.2I%F4 or Lil3eF3. ~

On t h e b a s i s OP the observed vapor composiLion, it appeam t h a t a l i q u i d compositi-on o f 88-12mole $ LiP-SeF2 wi.1.1 provide a vapoi' composi.ti.on of 67-33 mole $ TXF-SeF2. Hence 88-12 should he t h e c o r r e c t compostt i o n rin t h e s t i l - l pot f o r t'ne MSIi d i s t i l - l a t i o n process. This m e l t comp o s i t i o n i s cu?-ren"kl.y being measured t o confirm t h a t t h e vapor h a s Lhe cornposj.tion 67-33 mole $ L i F - B F ? . "be l a t t e r composition w0u.l.d serve as MSBR i'uel solvent (this solvent w i l l probah1.y not contain Z r F L ) .

Methods f o r Predi ctin8 Dpnsity, S p e c i f i c Heat, and ThPI-mal Conductivitj ~-~ i n Mol ten Fluoridie-G Density." Several y e a r s ago," after the published dz1;a on &ensj.ty of molten Y1uorid.e had. been examined, i - t w a s proposed t h a t t h e sirnp1.e iwle of a d d i t i v i t y of 1m1-a~vohmes might be veyy usefi1.1. for e s t i m a t i n g d e n s i - t i e s of fl-uoride melts. Since t h a t t i m e , t h e r e s u l - t s of all. addi-'ii ona,l. expe ri.me-ntal. i.n ve s t i g a t i o n s have been studi.e d. 'i'he r u l e of a d - d i t i v i t y of molar volunes appeared t o hold q u i t e well except f o r one system; t h i s was t h e NaP-.UFr, systcm12 where p o s i t i v e d e v i a t i o n s 8s p e a t a s 6$ were observed. Thus i'c appears t h a t , al-thou.gh there [nay be

131

Table 5 . 4 ,

C omp 0sition (mole $ ) LiF

.&E';?

Vapor-Pre,ssure Corlstant s

, Assuming

that, t h e Vapor

Phase i s Corriposed. of L i F arid ?kFz

Tempe r a t u r e Range

("c)

p LiF

897-1052

10.370

10.431

883-1036

10.437

13,330

13,890

895-105 5

9.7'20

1.3,330 12,350

9.4%3

3.2,270

8.611

10,'710

exceptions, t h e :rule of a d d i t i v e molar vo3:urfle 8 describes t'ne e,xperirnental da-La on molten f l u o r i d e s quite well and- remains t h e strflp1.estt most ac'curate method For precltcting i1ens;ities of fl.uuoride melts.

To improve t'ne me-bhod of e s t i m a t i o n , a revised set o f e m p i r i c a l molar volimes i s given i n Table 5.5. The ori-gin of t h e s e v a l u e s i.s d i s c u s s e d i n r e f . 1.0. For e s t i m a t i n g a densl-by- expression of' the form f i r s t solve f o r d-ensities a%

temperatures by !isLng the c2qu.a.tion n

M. are t h e mole :Fraction aid. gr'm-formula wel.gint of com1 porient i, <and V i ( - t ) is the molar volume of component i at -teir~perature5,. Subr;ti-tute molar volumes from Table 5.5 a t the t w o d i f f e r t s n t temperature:; in o r d e r t o obtairi the two va.lu.es of p., * s i n c e d e n s i t y i s l i n e a r with mnperature, s u b s t i t u t i o n of t h e two p aL' i r s of v a l u e s of p a.nd t; i.n Fq. t; (1)provides the solu-Lion f o r tine constants a aind b.

.&ere

md.

I-

S p e c i f i c Heat. Examination'o of t h e heat - c a p a c i t y measi.uwmnt s of mol-ten f l u o r i d e s i n d i c a t e d that the h e a t c a-p a c i t y per ~ram-atorn o f melt i s approximately 8 cal/"C. Hence an e q n - e s s i o n s i m i l a r t o t h a t of D L L ~ Q ~ ,

1.32 Table 5.5. ___lll.

Empirical Mol-ar Vo1.ume s o f Fluorides .-

__ll___l__

I_____..-

Molar Volume (cc/imole) _. ..-..

A t 600"C

.~-

l__l-

_l_.___l_

At; 800째C

____II.

i,iF

13.46

14.19

NaF

1.9.08

20.20

28.1-

30.0

RbF

33.9

36.1

40.2

43.1

52 F2

23.6

21:* 4

MgF2

22. li

21.3

CaF2

28.3

SrF2

27.5 30.4

BF2

35.8

37.3

26.9

30.7

34.6

35.5

LaF3

3'1.7

38 '7

Ce F,

36.3

37.6

PrF3

36.6

37.6

SlriF3

39.0

39.8

ZrFA

ThEr,

46.6

50 47 7

UFL,

45.5

46 7

C sF

Alp'3

YF3

and P e t i i may : b expression i s

31.6

used i o e s t i m a L e s p e c i f i c h e a t s o f fluoride melts.

8 e =

n i= 1. fl

'lk~

(Nipi)

1 (N.M.

i=1

....____

.......

(3)

1 I.

, ' g pi i s .'ilne number of w h e r e c i s the spec?-fie h e a t i n ea1 atorns i n a mol.ecule of conxponent i, and Ni and Mi are t h e mo1.e f r a c t i o n and -the gram.-fomula, weight;, respecti-vely, of component i.

133

Sample c a l c u l a t i o n :

or MSFE coolant, 66-34 inole (N.P.) I 1

C(N.14.) 1 1

Ls-&F~,

0.66(2) + 0 . 3 4 ( 3 )

0.66(26) + 0.34(&7)

Therma.1 Conduc ti i v i ty

2.34 =

33.1

0.157 ca,l (OK)-’ g-‘

A new semitheore t i c a1 express i 0x1 based on

Bridbyan’s theo-13~’~ of ener-gy t r a n s p o r t i n 1ri.qixids has been d-eveloped; t h e deri.vation of tlre method i s given i n ref. 10. The expression is

where k i:; -the tinema1 conductivity, V i s -the ~ n o l a rvolwne, and. ii i s t h e velocitjr o:? aoimtl i-n t h e melt; a l l three v a r i a b l e s sho1x:Ld. be i n c g s wirits. ‘Touse Eq. ( 4 ) , the molar volume and. velocity- o f sound are necessai-j. Mol.ar volume i.s e a s i l y est-irnated by the rule oY ad.dri.tivity as oiit’rined above. ‘ 1 2 velocity ~ of sound may be e s t i r m t m i frcm -therrmodyilamic cpmnL3.ties, using the e.xpression

where C

w e t h e mola,r h e a t c a p a c i t i e s at constant p r e s s u r e and V : volme, respectivel.y, CY. L s t h e er;l,ansivi_ty, T i s the absol.iite temperatuj-e, C /PI i s t h e specific h e a t [and should.be expressed. i-n e r g s (eIC)-’

g-l].

mid C

TTrie r a t i o C /G

P V

~ a r i ? sbetween 1..2 and 1.35 f o r most fused sal.ts

(1.2 works quite ve11). TIX expLwsivity is tlie negLz-tive of temperatur-e c o e f f i c i e n t of densrity, d i v i d e d by- the density; that i s ,

a=-yg) I,

By- using tlce additi-vity rule,

i s e a s i l y estimated.

Oxide S o L i i i 3 i l i t i e s i n MSRE Flush S a l t , Fk1 Salt, a n d !Their Ilixtures

Esti.mates of the oxide -tolerance o f MSEIE I’lush-salt--n-lel-sal-t rnixtxres r e p o r t e d p l - e ~ 0 u s ~ y i were 4 based upon t r a m s p i r a t i o n measu.rements of t h e ~ 0 1 . 1 . o ~ ~ ie- q n gu i l i b r i a :

HzO(g)

2F-(d) ;It-O”(d.)

2liP(g)

1.34

By combining t h e r e s u l t s for r e a c t i o n s ( 6 ) and (71, &0(s)

2F“-(d) + € k F z ( d )

0”.“(d)

estima-tes were obtaT.ned f o r t h e dissolved-oxide concentration ai; k O s a t u r a t i o n of ~ L ~ E ’ - B F(approxi.mately ~ the composition of MSRE f l u s h salt). For 2LiF-.&F2 melts cont;aj.ning more thail 0.1 mole/kg of ZrF4 wherein ZrO2 becomes the l e a s t - s o l u b l e oxide r e a c t i o n s ( 6 ) and (8) were cofn’oined i n a si-rflilar way t o o b t a i n e s t i m a t e s of t h e concentration ol” d.ri.ssol_ved oxide a t Z r 0 2 s a t u r a t i o n : -^

However, ’chese e s t i m a t e s weTe of I..i.mited accuracy, owing t o d-ri.ffj.culties i n the rlete-mination of Q by t h e t r a n s p i r a t i o n method. I n p a r L i c u i a r , 0 this quotient was Pound t o o l a r g e ’LO be measured. with u s e f u l accumcy i n t h e MSK3 f i e 1 composition, and h e m e it was necesszry t o estimate t h e oxide t o l e r a n c e of t h e i%el by e x t r a p o l a t i o n :from r e s u l t s f o r f i e 1 s a l t dilu-Led by flush sa1.i;. During t h e p a s t year, a more d i r e c t method for determining t h e s e oxide s o l u b i l i t i e s has been adopted. A measured volune of s a l - t , which previoiisly had. been sa-turated ’02- e q u i l i b r a t i o n w i t h excess s o l i d Zr02 or BeO, was passed upward through a s i n t e r e d nickel f i l t e r i n t o a heated r e a c t i o n v e s s e l (Fig. 5 . 2 ) . There it was sparged w i t h an Ha-Kti’mixture t o remove t h e dissolved oxide as HzO. The e f f l u e n t HI?-1I20-H~ mixture was passed through a sodiurn f l u o r i d e column maintained. zt 90°C t o remove t h e unreacted BF, and then it was passed. through. a Karl F i s c h e r ’ c i t r a t i o i ? assern’o1.y where t h e waker content was de t e m i n e d . ‘Typlcal.ly, 125-g samples of sal-t were filLerceil i n t o t h e upper vessel. and sparged with a gas flow o f 150 cm’/min a t a temperature o€ 500°C. The IIF p a r t i a l p r e s s u r e w a s 0.07 atin or l e s s . The time required t o ’i”emOVe essentia1.1.y a l l of t h e oxide increased as t h e ZrF4 con’cent, of t h e mix’cures was increased, h u t s e n e r a l l y d i d not exceed. 4 h r . The b h n k w a s u s u a l l y equival-ent t o l e s s -tilai? 0.002 mole p e r kg of oxide in the saimple.

135 The r e s u l t s obtained by t h i s method f o r simulated f l u s h - s a l t - m e 1 salt mixlures (Fig. 5.3) a r e i n reasonable agreement with prevrious e s t i m a t e s ; 1 4 that i s , a s ZrFr, ( p r e s e n t i n MSRE f u e l ) i s adcled t o 2LiF&F2 ( f l u s h s a l t ) , t h e oxide t o l e r a n c e a t f i r s t f a l l s , reaches a minimum, and t h e n rises. This behavior r e f l e c t s a monoto-nic i n c r e a s e i n t h e s o l u b i l i t y product

%r O 2

with ZrFA conceIitration ( t h e dashed l i n e s

sh.own i n Fig. 5.3 Lnclicate t h e behavior which would be found i f

%r02

The temperature d.epenclence of t h e oxide tolerance remained c o n s t a n t ) (I) t h e flush s a l t , i s i n d i c a t e d i n Fig. 5.4 for t h r e e compositions: ( 2 ) the approximate composition of minimzvn oxicle t o l e r a n c e , and ( 3 ) -Lhe fuel s a l t . When t h e p r e s e n t d i r e c t l y measured values of with p r e v i o u s l y determinedl4 values of

Qzro

a r e combined

i n t h e expression

improved e s t i m a t e s a r e obtained for the e q u i l i b r i u m q u o t i e n t

Qo (Table

5.6), correspoizdlng t o r e a c t i o n ( 6 ) . â&#x20AC;&#x2122;This q u o t i e n t should be u s e f i l i n p r e d i c t i n g the e f f i c i e n c y of oxide Ternoval from MSRE f u e l s a l t by HF sparging during Fuel reprocessingL5 and during oxide analysis~ l d

The s o l u b i l t t y r e s u l t s obtained t h u s f a r f o r Be0 i n 2LiF-BeF2 (Fig.

5.4) a r e somewhat above t h e previous values obtained by combination of

QB and

Q0,14

but t h e s e new r e s u l t s showed c o n s i d e r a b l e scatter. T h i s

0RNL.-OWG 66-4780

PROBE FOR DEPTH MEASUREMENTS-

METER ANHYDROUS HF IN CONSTANTTENIFEf?ATURE BBTH

F i g . 5.2. fluorination.

.............

Apparatus for Deterillination of SolubiZities b y Hydro-

136 at

SALT I N F L U S H SALT 5 10 20

FUEL

I - T I 1

ORNL-DWG

77TI

66-4781

100

I I

F i g . 5.3. Oxide Concentration iieqii5.red t o Produce P r e c i p i t a t i o n of B e 0 o r ZrO;! from Simulated MSRE Plush-Salt-Fuel-Sait Mixtures.

i~stllought t o be caused by t h e presence of f i n e l y divided. Be0 whTi.ch was not f l l t e r e d compI.etely from all^ t h e samples. These measuremen'is are beiiig repeated with t h e use of longer e q x . l i b r i 1 m times, i n t h e hope Yne oxide t o l e r a n c e t'nat t h i s w i l l improve t h e f i l t e r a b i l i t y of t h e &0. o f 2LiF-&F, ( f l u s h s a l t ) , h d i c a t e d by t h e l i n e s i n Fi-gs. 5.3 and 5.4, repi-e s e n t s our be st e s-tri.ma-tea t pre s e n t . Separations i n Molten Fluorides Evaporativz - D i s t i l l a t i o n Studies on Molten-Salt Fuel -.. Components

. . I

Vacuum d.ri.stillation s e p a r a t i o n of mol-ten-salt f'ueI o r f u e l components from t h e r a r e - e a r t h f i s s i o n produc'is i s an a t t r a c t i v e method o f decr'easing neutron l o s s e s by capture. To design process equ?.pm?nt f o r t h i s t a s k , both the m a s s r a t e of d i s t i l l a t i o n and t h e r e l a t i v e vol.atilii;y of the rare earyns must, be known f o r t h e p a r t j . c u l a r s a l t system used. Completed experiments concern t h e process demonstration planned on MSIB ~?uel,b u t a r e d i r e c t l y a p p l i c a b l e t o any proposed thermal MSBR fuel..

For bElG3 f u e l , yemoval of t h e u-i-aniurn by f l u o r i n a - t l o n i s proposed. The fuel solvent and remaining f i s s i o n products would t h e n be f e d a t the d - i s t i l l - a t i o n r a t e .Lo a vacuum s t i l l . charged. with LtF-13eF2 -ZrFlk a-i; t h a t compositi.on which w i l l y i e l d t h e -fie1.solvent a s d i s t i l l e d product; the r a r e - e a r t h F i s s i o n products would concentrate i n t h e s t i l l . . The residue: would be driscarded OT processed, when necessita-Led by h e a t from t h e fi-ssion products or concentration of r a r e e a r t h s i.n t h e product.

1.37 ORNL-DWG

650

700

0.05

550

600

66-4782

("C)

TEMPERATURE

500

............

1500

0 02

13n

x \

0 0)

z 0

0.01

...

F-

+ z W

0.005

1: Ih

0.002

20 0.001 1 .o

1 .1

1.3

1.2 'ooo/T

(OK)

Fig. 5.4. 'Temperature Dependence of Oxide Tolerance: (1)i n Flush Salt; (BeO-Saturated), ( 2 ) i n Flush-Salt-Fuel-Salt Mixture of M i n i m u m Oxide Tolerance, and ( 3 ) i n F u e l Salt.

Table 5.6.

Swnmary of E y i x i l i b r i w n Quotients f o r

Reactions (6), ( 8 ) , and (10) i n MSIa Fuel S a l t

500

0 01.2

600

0.024

700

0,041

1 . 8 x 10-4

'7.3 x 10-4

2.1 x 10-3

7.1 x lo-2 3.95 x 10-1 150

3.G x

1-7x 5.6 x

lor

138

A I O - m l g r a p h i t e cylinder, containing -1.7 g of s a l t wit'n a f r e e surface (when mol.tei1) of 1 em2, w a s used f o r t h e sti7.1. p o t . Tl?is cyl5.nd.er f i t t e d i n t o a " ff' shaped Hastell.oy N -tube h e a k d . e l e c t r i c a l l y t o a given temperature a,s measured by four thermocouples i n .the graphi-te c y l i n d e r . When t h e d e s i r e d tempera-Lure was reached, disti.l.lation w a s i n i - t i a t e d . by evacuating t h e assembly. Vapori.zcd sa1.t t'nen passed up and over t h e t o p of t h e "n" with a s m a l l p o r t i o n ( a t t r i . b u t e d t o thermal r e f l u x ) c o l l e c t i n g a t t h e base of t h e g r a p h i t e c y l i n d e r . The product sa.1.t condensed i.n a c o o l e r (-.A5O0C) collectj-ng cup i n t h e opposite l e g . D i s t i l l a t i o n was stopped by helium addi-tion a f t e r presel-ectcd ti.me pe si.od.s

Mass-rate d a t a f o r 7LiE' were deter-ni.ned f i r s t , and t h e n MSRF: solveiit was added. t o -the /XAF and d.ri.stilled i n a l i q u o t p o r t i o n s from i t . Each r e p e t i t i o n brought -the BeF2 and. ZrF), concentra-tions in -the p o t el-oser '-iotliose which woul-d yield- fuel solvent (Li.F-kF2 - Z r F q , 65-30-5 mole $1 a s produc-t After the equi1ibrj.mil concentration w a s approached, 2200 ppm of neodymi.um ( a s NdF3) w a s added t o t h e s t i l l bottom, and seveyal d i s - t l i l l a t e sariple s were taken. Then tine nzodymi.v;m concentra.t:,ion was r a i s e d Lo 22,000 p p , and t h e sequence w a s repeated. For both 7LiF and .i;he nominal equj.librium composition, t h e e f f e c t of temperature on m a s s r a t z was de t e mined.. T-

The data, of Fig. 5.5 show Yne e f f e c t of 'Lernperature and mass r a t e ; s i n g l e experiments show considerable s c a t t e r , s o incl.usive bands a r e shokirl. The slope of t h c barids i.s consisten-t with t h e h e a t of vaporizat i o n of t h e components and ski-ongly suggests t h a t e b u l l i t i o n does not occur. Solvent surface h e a t flux i s <1/100 of' t h e avai-lable h e a t Lo t h e g r a p h i t e cylinder; it i s d-oubtful t h a t t h e d i - s t i l l a t j - o n i s h e a t l i i n l t e d . The f a c t 'chat t h e o b s e n e d rate f o r 7LiF 7.s only -I.$ of

10-2

UHNL-OWb 66 966

Fig. 5.5.

Observed Di s t i l l a t i o n Rate vs Temperature.

139

t h e o r e t i c a l i s unexplained, b u t it has been o b s e r w d i n many d i s t i l l a Lions u s i n g se-vera1 expesimental configu.ra.t;ions.

Tne s o l v e n t f o r xny proposed. bEBR :;houl.d d i s t i l l a t sates above -that; shown for 7LiF w i t h %lie p o s s i b l e exception of 'I%Fr,-bearing systems. The e f f e c t of 'TbFq i s being s-t;u&ied.. E f f e c t i v e n e s s of s e p a r a t i o n from r a r e earths was dstermined by xctj.vai;l.m analysls Tor nc?odymiutii in t'ne product, t h e s t i l l bottom, arid t h e refluxed s a l t d e p o s i t e d areoimd the base of the g r a p h i t e , The d.a.t;a a r e shown i n . Table 5.7.

%ne e q u i l i b r i u m comp'osi.ti.on i n t h e s t i l l pot u.ndoubted2.y changes w i . t h temperature due t o t h e change i n a c t i v i t y c o e f f i c i e n t s of -the components e 'The composl-Lion found at nominal eqni.I.ibric?m a f t e r several s o l v e n t add-itions of 5 t o 7% by wetghi; and a f t e r dis.t;illatioiis rat 1030째C was Lip-ReFz-ZrFq (8.5.4-10.7-3.9) i n t h e presence of 22,OOCl pprri of neorlymium as f l u o r i d e .

E f f e c t j. ve A c t i v i t y Coeffli c: Lent s by E.vap ora t i ~ I)i e stiIlat ion Evaporation i n t o a 'vatu-utn fi-oin a. q i ~ isec e n t molten- :XU mTxture of I-ow vapor p r e ssi11-e shord.d n o t permit vapoy-liquid e yuilibrilmi a.-1; t h e s u r f a c e o-f the melt; t r a n s p o r t from the surface shoul.d '02 c o n t r o l l e d by t h e e v a p o r a t i o n rates of tine individixil components "lie amount vapor p r e s s u r e , molecular vaporized i s a fuiiction o f %he ~quil~j.brium mass, temperature, and s u r r a c e area; according t o Langmuir, ' - 7 a

Y i s vapor p r e s s u r e of component Z, 14 i s molecular weight of corriponent Z, T i s absol.ut;e .terri-ge-i-ature arid K is a c o n s t a n t dependent

ly"liere

OT1 1mtt5

I n a niulticorriponent system a t equi.7.ibriu-m,

Table 5.7.

Concentrati-on of Neodyinilm i n Fractions from Vacuum D i s t i l l a t i - o n s N d Concentration

2200 p p Added ~

22,000 ppm Aadej

2570

22,000

S t i l l bottom

P roduc t

Re ?lux

600b

133 __I.^

3A ___I.I.____

.... ~

%esn values from s e v e r a l detemiinations; d.ata show l i t t l e s c a t t e r except f o r ref]-ux specimens. bThese product samples a l s o show2d Ce and L a , which un6oubted.l.y represent contamina-tiom during gr.iiidri.ng and. handling of specimens; Nd analysis, th@refoi.e, may well be t o o high.

altered t o

Proceed.ing with t h i s tec'nniqix?, t h e d a t a shown in I3g. 5.6 have been taken Tram LiP-IkF2 -ZrFq mel-ts. For comparison purposes, s e l e c t e d d a t a from o t h e r sources a r e included.18--20 Al-though I.nterna3. consistency z x i s t s , the values a r e dependent on vapor-pressure d a t a f o r t h e pure coinponeiits. Ca1ciil.ation.s were made using t h e Val-ues ( P o ) f o r tile pure compon2nts shown i n Table 5.8. The I eas-t-precise measurements a r e fyom MSl8-solvent d i s t i l l - a t i o n s ; t h e s e a r e i.ilclud.ed t o s u b s t a n t i a t e t h e su-mi-se Ynat when ZrFA. i s i.ncluded i n t h e melt,, it e f f e c t i v e l y removes LiF' Yrom t h e s o l v e n t . The 1000째C LLF-BFz I.ine has been extended 'LO 100 mole $ Lip, since t h e i n i t i a l LiF-BeF2-ZrFL) experiment contained <0,35 mole $ ZrEd., a quan.tity s o small t h a t file cystern can be assumed t o be LiF-BeF2. On t h e o t h e r hand, as Z r F A b u i l d s up i n Lhe inixed system ( t o approximately 3 mole $), enhaaceieni; of t h e BeP2 a c t i v i t y i s iloted; 'chis i s consis-tent wi-t'ri Tes u l t s from MSRE solvent (LiF-EeFZ -ZrFIF,l 65-30-5 mole $ i n i t i a l l y ) . Tne temperatures r e p o r t e d a r e -those of t h e bulk m.eJ_t, and it i s recognized that, t h e sui-t'ace teiipei-ature may be s i g n i f i c a n t l y lower, causing an indeteimlnata ( f o r t h e preseii-i;) e r r o r . Both surfacs-temperat u r e e f f e c t s and .the pure LiF-Zi-FA system a r e being s t u d i c a . It i s i n t e r e s t i n g to note t h a t t h e assumption of unj-.f, a.cf;i.v:~ty c o e f f i c i e n t f o r LiE' does no-i I.ead -to j.ncomyati.biliLy with the d a t a o f others.

E x t r a c t i o n of Rare E a r t h s from Molten Fluorides i n t o Molten Meta1.s S t u d i e s of -the rernova.1 of rare c a z t h s from a molteii-fl.inorlde solvent and. t h e i r dissolution i n . molten n c t a l s have been o r i e r r k d toward t h e development of a liql~.i~cl.-lriqui.d e x t r a c t i o n process for re mo.vi% rare-earth fission produc-1;s from m o l t e n - s a l t reactor f u e l s . Fluoride mixtures obtained by dissolving a s e k c t e ? rare e a r t h i n t o LiF-ZieF;! (66-34mole $) Yiave been used. t o simulate t'rre fuel- s o l v e n t of the re-f'ercnce-d.er,ign MSBR. In !&el reprocesslng schemes proposed. fo-r the reactor, uranium will- be removed p r i o r -Lo t h e reraoval of nonORNL-DWG 6 6 - 3 6 7

t0-'

2 L I F . B ~ I ' ~ + Z ~ BFA~E,S l

DERIVED

FROM

MSRE S O L V E N T

GISTILLATIONS

900-1050째C

LiF-9eF2, BUCHLER, 600째C

I.iF.8eFZ. l0OO'C L i F . B e F z , 900째C

CI,. 65

LiF*BeF.z.LrF4,

.........-. ........

1000째C

!DO

LiF I N MELT ( m o l e 7,)

Fig. 5.6. Effective A c t i v i t y Coefficients Calculated from E v q o r s t i v e - D i s t i l l a t i o n Data f o r MSBR Solvent Compositions.

142 Table 5.8. .--_.--

Vapor Pressures foi- Fb.re Fluoridesa,b,c .........

C omp ouiid ..

1.000" c

_ I I _

Vapor Pre ssu-re (mm IT&)

_ _ I -

900" c

.....

o_ll

L iF

0.47

0.072

12.0

2700

780

a. _ Handbook _l__.l.. ........of . Chemis-Lry .... and Pi1;vsis-s 44th ed. Rubber Publishing Co., Cleveland, Ohio, 1952.

, p.

2438, Cheizical

bB. Pol-ter and E . A. Browfi, J. Am- Cemm. S O C . 45, 49 (1962). C

S. Cantor, pe-rsonal communication.

v o l a t i l e f i s s i o n produc-Ls. When t h i s simulated f u e l mixtiure i s contacted with a molten bismuth-lithium mixture, r a r e e a r t h s a-re reduced t o t h z i r elemental valence s t a t e s and a r e d.lssolved i n thi. mol'cen---metal phase. Experimental s t u d i e s conducted t h u s P a r h%ve examined t h e d i s t r i b u t i o n o f r a r e earLhs between t h e two I.i.qu3.d phases a s functions o f t h e I.i.tbi.um concentration i n t h e metal phase. Sirbsequent experiments: w i l l e l a b o r a t e on t h e w f i n d i n g s and w i l l examine -Yne back extracti-on of rare e a r t h s from the l i q u i d metal- i n t o a second s a l - t mixture. The remo.jal of r a r e earths from t h e reactor f u e l , foll.owedby t h e i r eoncent r a t i - o n i n a s o l i d , disposable s a l t mixture wi.11 cons-ti-tutr -the r e proce ssi.n.2 method. li'luor.ide s t a r t i n g m a t e r i a l s were prepared i n n i c k e l equipment by adding s u f f i c i e n t rare-eart'n f l u o r i d e t o approximately 2 kg of the solvent LLF-BeF;! ( 6 6 - 3 4 mole $ ) t o a-L-ta.lna rare-ea-rtb concentrati-on of a.bomt lo-' m.f. i n the s a l t phase. When p o s s i b l e , a selec-Led rad.j,oisotope of t h e r a r e e a r t h w a s added f o r anal-ytical p i r p o s e s . The mix-Lure wa;; treated. wi.th an HF-H2 mixture a t 600째C t o remove oxide irnpiiriti.es with 112 alone t o red-iizce concentrati.ons of st,ruci;ural-rnetal.. and a t 700"~ dj-yluorides i n t h e f l u o r i d e melt. The bismuth was purif-j_ed.by sparging t h e 2.35-kg batch wit'n 13% a t 600째C t o remove oxide i m p u r i t i e s . The bismuth p u r l f i c a t i o n w a s c a r r i e d out i n the experimental. e x t r a c t i o n v e s s e l of type 3041, s t a i n l e s s s t e e l l i n e d with low-carbon s-tee].. Foll.llowi n g t h c matt.r1;71.;,;.-.prepa~ration phase of t h e elrperiment t h e I"luori.de mixt u r e was t r a n s f e r r e d a s a l i q u i d t o t h e extractlion v e s s e l . Lithium metal was added d i r e c t l y t o t h e m e t a l phase without p r i o r contact with Lhe s a l t phase; tblis was d.one through a loading port t h a t exteiid.ec3. t o near t h e bottom ol" the e x t r a c t i o n v e s s e l . Z,ri.thj.um, for incremental addliti.ons t o t h e eqerimen'c, w a s f r h e s h l y c u t and weighed. under mineral o i l , affi-xed t o a small-diameter s t e e l rod, rinsed. i n benzene, and d r k d . tn tine ??lowing i n e r t atmosphere of -the loatl.ing p o r t prior t o i.ts

143 i n s e r t i o n and d i s s o l u t i o n i n t h e molten bismuth. F i l t e r e d samples of each phase were t a k e n under assumed e q u i l i b r i u m c o n d i t i o n s (approximately 2-hr p e r i o d s ) a f t e r each add-ition of l i t h i v m . Radiochemical analyses of each phase f o r r a r e - e a r t h garma a c t i v i t y and spectrographic a n a l y s e s of t h e m e t a l phase for r a r e - e a r t h and l i t h i u m c o n c e n t r a t i o n s provided d a t a f o r c a l c u l a t i n g t h e d i s t r i b u t i o n of t h e r a r e e a r t h i n t h e system and i t s dependence on t h e 1i.Lhium c o n c e n t r a t i o n of t h e metal phase. I n experiments conduetea t h u s far, t h e d i s t r i b u t i o n s OS lanthanum, cerium, neodymium, sarmariwri, and europium i n t h e e x t r a c t i o n system have been examined s e p a r a t e l y , but under essen-tia1l.y comparative c o n d i t i o n s . A surmna-ry of t h e s e r e s u l t s , i l l u s t r a t e d i n Fig. 5.7, shows t h a t a mixture of bismuth c o n t a i n i n g 0.02 m.f. of 1ithiLm metal s u f f i c e d f o r removing e s s e n t i a l l y a l l cer;ium, lanthanum, and neodymium and s u b s t a n t i a l q u a n t i t i e s of samarium and europium from t h e b a r r e n f u e l s o l v e n t . I n a l l of t h e experiments, rare e a r t h s t h a t were reduced from s o l u t i o n i n t h e s a l t phase were found as drissolved components of t h e metal phase. Each incremental a d d i t i o n of l i t h i u r n t o the system r e s u l t e d i n a n e a r - l i n e a r i n c r e a s e i n t h e c o n c e n t r a t i o n of l i t h i u m found i n t h e metal phase. However, t h i s d i s s o l v e d q u a n t i t y accounted f o r only 25 t o 5% of t h e amount added t o t h e system. The results of a blank e x t r a c t i o n experiment i n which r a r e e a r t h s were omitted from t h e system could not be d j s t i n g u i s h e d from those o b t a h e d when r a r e e a r t h s were p r e s e n t . Each incremental a d d i t i o n of l i t h i u m t o an e x t r a c t i o n system w a s an approximate t h r e e f o l d excess over t h e amount r e q u i r e d for the s t o i c h i o m e t r i c r e d u c t i o n of a l l of t h e r a r e e a r t h contained i n t h e e x p r i r n e n t .

- ~ ~I T ORNL-OWG

.................. .

.ITHIIJM

1 I:OIJNI)

r A!.

~~~~

66-4783

SAMARIUh CfHlUM

1.4Nl-HAN ?JEODYMI EUROPlUh

3 4 5 PHASE (mole f r a c t i o n x I O 2 )

F i g , 5.7. E x t r a c t i o n of Rare :E a r t h s from LS-BeF;! (66-34 Mole i n t o Z i s m i ~ L hby the Addition of Lithiwri Metal. at 6 0 O o C .

'$1

144 I n e a r l i e r experimen.ts, b e - q l l i u m metal w a s success%crlly u.sed 3.n place of li.thi.um m e t a l f o r the reduction of mi-e e a r t h s . Spectrographic analyses of -the metal. phase a l s o showed t h a t the l i t h i u m concentration i n bismuth increased as the extr.actri.oii of r a r e e a r t h s proceeded., These r e s u l t s impkied t h a t t h e r e a c t i o n k 0 -1. 2

~ - GiB F ~ +

v a s of s i g n i f i c a n c e t o Lhe reduction of rare eai-ths. Accordingl:y, l i t h i u m w a s used. a s a soluble component i n the rnet,al- phase i n place of beryllium, which i s not soluble i.n e i t h e r l i q u i d phase. The reductrion of r a r e - e a r t h f l u o r i d e s by l i . t ' n i u m 3.s expected Lo proceed by t h e r e a c t i o n di0-I- (RE)

4-m --IIEO

mz,1.

where m i s t h e e f f e c t i v e val,ence of t h e r a r e - e a r t h cati-on. I f u n i t ac-ti.vities p r e v a i l f o r a l l metal species i n t h c s a l t phase and for a l l i o n i c s p e c i e s i n t h e metal phase, t h e n the a c t i v i t y of lithiurn dissolved. ?.a t h e metal phase can be expressed as a f u n c t i o n of o t h e r a c t i v i t i e s i n t h e system a s (amO)rne'ial

"Li'

LiF

salt

Ka (am

salt

assumins thak t h e a c t i - v i t y of LiF and t h e acti.vri.ty c o e f f i c i e n t s of FBo, and " ' E H remain. constant, t h e dependence of r a r e - e a r t h distrri.bution on tile l.it'nium conccntration can be expressed as '1.1O3. ,

m Q Lio

D = KN

where D i s t h e i-atio of the mole fract,?.on of r a r e e a r t h i n the metal. phase t o t'ne mole f r a c t i o n of r a r e ear-Lh i n -'-Lhe sa3-1; phase, and

YLiO

..... ~

metal

salt

A plot of t h e experimental dzta according t o t h e logaritluiiic foim oâ&#x201A;Ź -this equation i.s sho~wnas Fig. 5.8. Val.aes f o r m and K cal-cullated

from t h e slopes and i n t e r c e p t s of t h i s p1xi.t a r e as folLows: Ra-t-e Earth Lan iiianurn Cerium

107

2.7

2.5

2.3

3.8 x 106

N e odymimi

2.5

Samarium

1.6

Europium

1.9

2-5 x lo6 1.8 x 104 5.9 x

io3

145

0.01

0.1

4 10 100 MOLF. F H A C l l C N OF RARE â&#x201A;ŹART.?. IN N E T A L

1000

MU1.E FYW,TION OF RARE EARTH IN S A L 1

F i g . 5.8. E f f e c t of Lithium Concentration i n P4etal Phase OD t h e D i s t r i b u t i o n of Rare E a r t h s Between LiF-BeF2 (66-34. Mole $1 and Bismuth a t 600'~.

Although t h e apparent f r a c t i o n a l exponents for t h e r e d u c t i o n rea c t i o n s are a s y e t unexplained, t h e results a r e i n rough agreement with t h e occurrence of lanthanum, cerium, and neodymium a s t r i v a l e n t i o n s i n t h e s a l t mixture; samarium and europium are probiibly reduced Lo t n e i r d i v a l e n t s t a t e s p r i o r t o t h e i r e x t r a c t i o n i n t o t h e nietsl phase.

Removal of P r o t a c t i n i u m R e m o v a l of Protactinium from Molten F l u o r i d e s by 0xid.e Precripita-Lion. Since a s i n g l e - r e g i o n m o l t e n - s a l t b r e e d e r r e a c t o r w o ~ d di n corporate the f e r t i l e m a t e r i a l i n t h e r e a c t o r fuel rnixture, chemical reprocessing schemes f o r recoverj-ng 233U could be 1riad.e m.ore effective i f 2 3 3 ~ a i, t s p r e c u r s o r , could be removed without a l t e r a t i o n 01" t h e r e l a t i v e l y l a r g e uranium c o n c e n t r a t i o n i n t h e -me1 mixture. Tne prec i p i t a t i o n of an oxide of protaetiniLun by t h e d e l i b e r a t e a d d i t i o n of oxide i o n may provide t h e b a s i s for such a reprocessing method i f t h e sirnultaneous p r e c i p i t a t i o n of U02 can be avoided. Previous s1;ud:i.e~ hare demonstrated t h e chemical f e a s i b i l i t y of oxide p r e c i p i - t a k i o n for removing p r o t a c t i n i u m from a f l u o r i d e mixture, L i F - B F 2 -rThF4 (6'7-18-15 mole $), proposed as t h e b l a n k e t of a two-region molten-salt breeder reactor. 2 1

I n the f l u o r i d e fuel mixture of t h e MSE, s u f f i c i e n t ZrF4 has been added t o accommoda-t;e gross oxide con-tarnination without l o s s of uranium from s o l u t i o n as UO2. Z a r l i e r skudies ha4 demonstrated t h a t U02 would n o t p r e c i p i t a t e at 700Â°C from t h e s o l v e n t , LiF-BeF~ (66-34 mole 8) w i t h added UFi+ and ZrP'4, u n t i l t h e c o n c e n t r a t i o n r a t i o of ZrFI, t o UFi+ dropped below about, 1.5. 2 2 "?ier.ePore a preIiininary study was made 03 the p r e c l p l t a t i o n of Pa02 from a f l u o r i d e mixtu.re known t o have 2x02 a s the stable oxide

The fluoride ixixture c o n s i s t e d of LiF-PeF2 (46-34 mole $ ) x i t h added ZrP, equivalerit t o 0.5 mole of zirconiurfl per kilogram of" s a l t mixture. About 1 me of 233Pa w a s included i n t h e salt prepara:tfon a s

i r r a d i a t e d '11102. The mix'iure was p r e t r e a t e d with anhyd.rous :IF and 132 t o convert oxides t o I h r o r i d e s .

The delibel-aLe introductrion of solid-phase oxide t o t h e melt was made by adding Zr02 i n s m a l l i n c r z n e n t s . Eil.tered s m p l e s of -the s a l t mix'iirre were taken a t assumed equil5.briu:m conditions a f ' t e r each Oxide addi-Lioi? and were analyzed f o r 233Pa by gamma spectrometry. The r e s u l t s of thesc analyses showed t h a t approximately 8% o f t h e 233Pa a c t i v i t y w a s removed a f t e r t h e a d d i t i o n of' about 67.5 g of ZrO2 (equi.valent t o 0.1.25 mole per kil-ogrmn of salt) t o the m?xture.

Ii' protactiniwn ej-ther formed a l a b i l e s o l i d solu-Lion with Zr02 or w a s removed from soluti-on on t h e s a l t mixture by surface adsoryti.on on Zr02, 'ciien i t s d i s t r i b u t j - o n c o e f f i c i e n t shou.ld have remained constant. The -Praction of protactinium remaining i n the l i q u i d phase could t h e n

be expressed as a I.-i.near f u n c t i o n of added. Z r O z by t h e equation

where D

[paloxide /[Palsalt,

Fpa

f r a c t i o n of Pa i n t h c sal.t, and W

i s t h e weight of t h e designaied phase. A n i o t e r y r e t a i i o n of the exp2rimental d a t a according t o t h i s l i n e a r function, shomi i n b ' i g . 5.9, ORNL-DWG 6 6 - 9 6 9

WZrO,

ips A LT

= W E I G H T R A T I O OF P H A S E S

CONC O F Pa. IN S O L I D PHASE-

___^__.

CONC OF Po IN LIQUID PHASE

W E I G H T OF Z r O p ADDED AS Sol-ID P H A S E

(g)

P i g . 5.9. Removal of 233Pa f r o m S o l u t i o n i n L i F - B d ' z (66-34-Mole w i t h Added Z r F 4 (0.5 Mole per K i l o g r m o f Salt,)by Addition of ZrO2 at

600째C.

i l l i i s t r a t e s t h e constancy o f t h e d i s t r i b u t i o n c o e f f i c i e n t a t a calculated value of about 237. The d a t a f b r t h e r suggest t h a t about 7 g o f t h e i n i t i a l ZrOz a d d i t i o n p a r t i a l l y d i s s o l v e d i n t h e s a l t phase or was otherwise lost from t h e r e a c t i o n mixture. Further experiments w i l l i n c l u d e s t u d i e s of t h e e f f e c t of Z r O 2 s u r f a c e a r e a on p r o t a c t i n i u m r e moval Trom s a l t mixtures proposed f o r a s i n g l e - r e g i o n m o l t e n - s a l t b r e e d e r reactor. Removal of Protactinium from Molten F l u o r i d e s by Reduction Processes.

The e f f e c t i v e recovery of 233Pa from a m o l t e n - s a l t breeder r e a c t o r will provide more economic production oz" f i s s i o n a b l e 233LJ by s u b s t a n t i a l l y reducing b l a n k e t inventory and equipment c o s t s and by improving neutron u t i l i z a t i o n . Ac c ordingly cherai c a l de ve1opment e f f o r t s srippo r L i n g t h e r e ference-design MSBR a r e concerned w i t h t h e removal of p r o t a c t i n i w n from t h e b l a n k e t mixture, LIF-BeF2-ThF4 (73-2-25 mole $), by methods which can be f e a s f b l y ad-apted as chemical processes. P a experimental program h a s been i n i t i a t e d t o study the r e d u c t i o n of p r o t a c t i n i u m f l u o r i d e s from t h i s s a l t mixture by molten l e a d o r bismuth m t u r a t e d with thorium metal a t about 400째C. It w a s hoped t h a t protactiYlj.wi, as PaF4 i n t h e s a l t phase, would be reduced t o it:; m e t a l l i c s t a t e by thorium m e t a l and could be recovered i n t h e molten lead 01'oismut,h.

The primary o b j e c t i v e of i n i t i a l experiments with t h i s program h a s been t h e study o f p r o t a c t i n i u m removal from t h e s a l t phase of' t h e ext r a c t i o n system. For t h e s e experiments s u f f i c i e n t ; 3Pa was obtained f o r radiochemical a n a l y s i s by neutron i r r a d i a t i o n o f n small quanti-Ly The simulated b l a n k e t mixture w a s prepared from i t s components, of 'Tho,. t o g e t h e r with t h e i r r a d i a t e d Tho;!, i n n i c k e l equipment. This n i x t u r e was t r e a t e d a t G0O"C with an HF-Hz niixture ( 1 : l O volume r a t i o ) t o remove oxide i o n and a t 700'C with H2 alone t o reduce s t - r u c t u r a l - m e t a l i m p u r i t i e s . The metal-phase e x t r a c t a n t , l e a d o r bismuth with added thorium metal, 'was prepared i n t h e e x t r a c t i o n vessel ( t y p e 304L s t a i n less s t e e l with a low-carbon s t e e l l i n e r ) by treatment with H2 n t 600째C. The e x t r a c t i o n experiments were started by t r a n s f e r r i n g 8 kaown q u a n t i t y of t h e prepared s a l t mixture i n t o the e x t r a c t i o n v e s s e l containirqq t h e metal-phase e x t r a c t a n t . F i l t e r e d samples of t h e s a l t phase were taken p e r i o d i c a l l y f o r radiocheinieal a n a l y s i s o f d i s s o l v e d protactinium. I n each experiment, 233Pa w a s r a p i d l y removed from t h e s a l t phase and reinained absent from t h e solution during t h e approximately 100 h r a t 600째C while t e s t s were niade. Subsequent h y d r o f l u o r i n a t i o n of t h e ext r a c t i o n system with a n RF-H;! mixture (1:20 volume r a t i o ) showed t h a t 33Pa could be r a p i d l y and almost q u a n t i t a t i v e l y returned t o s o l u t i o n i n t h e s a l t phase. Typical reswlts of t h e s e e q e r i m e n t s are shown i n Fig. 5.10. In t h i s experiment, thorium metal was added a f t e r t h e s a l t mixture w a s introduced i n t o t h e e x t r a c t i o n vessel t o demonstrate t h e n e c e s s i t y of the r e d u c t i o n r e a c t i o n .

The o b j e c t i v e of experiments now i n p r o g r e s s i s t o examine methods for recoverzng 233Pa from t h e e x t r a c t i o n system. The proposed- use of macro q u a a t i t i e s 02 231Pa may be required. t o circwnven-t the a n t i c i p a t e d a d s o r p t i o n of t h e micro q u a n t i t i e s of 233Pa, c u r r e n t l y used, on t h e walls of t h e c o n t a i n e r , or on o t h e r i n s o l u b l e s p e c i e s i n t h e system.

Additional s t u d i e s of' t h e d e l i b e r a t e precipri ta-Lion and. adsorp'i-j-on of 233€'a on s o l i d , s t a t i o n a r y be& such a s s t e e l wcoi w i l l . bc i-n.ad-c i"iA comparative c vsl;na-Lion.

Current s t u d i e s oi" Lile re__^l-.l_ i__nl liolten Lead. _.. ---SoiubilitJ- o_"Thorium moval of -p r o ~ a c t i n i u mfrom a molten f i u o r i de mixiu~e,which s i n i i z l a t e s the b1aizlic.t of' t h e reference-deslgii MSRRi have Seen di.rcc Led LO t h e development of a li[yxi$-Mquid e x t r a c t i o n process. The met proposes t h a t protactiniurt, as PaF4 i.n a s a l t phase, can be r e its rnetal.1i.c state anti e x t r a c t e d jnko 2 molteii x e t a l phasc-. The p;si.~ble use of a rnolteii mixture of thorium i i j l e a d would provide a convfiL:ienL meii-iod f o r co&ining t h e r e d u c i n g agent with the metal-phase e x t r a c t m t and ?or replenishing t h o r i i m t o t h e I"l.uoride blanket :.?ixture. 'YE o b j e c t i v e of t h i s study has been 'GO cs-Lablisli Vile solubj-li~tyof thorium 2n l e a d over t h e temperature range of i n t e r e s t t o t h i s program and t o provide a lead-thorium s o l u t i o n of kiiowm composj.tion f o r siLbseqJent p r G t a C t i i l i W n l e x t r a c t i o n exper;.ment s ,

The expcrimenLal mixture con-tained i n low-carbon sLeel-, consisted of approximately 3 kg oi' l e a d and 1.00g of thorium-metal c h i p s . Values f o r t h e solubi3.ity of -Lhoriurn were obtained. by analyses of fii-'cered sr;.r;Les wiihdmwn from t h e melt a t se_l.ectcd t c n p e r a t u * e s 0TiF:r t h e i n t e r v a l 400 t o 600°C u.nder ~ G S W I Eequilibrium ~ condi.tions. Samples were withdrawi during two hea-Ling and cooling cycles and siibmikted f o r a c t i v a t i o n and. spectrographic analyses. Thcse r e s u l t s , p l o t t e d as t h e logarithm or' tlie s o l u b i l i t y vs thc r c c i p r o c a l of thc absolu.-ce temperature i n F i g . 5.11, i n d i c a t e tha.t t h e heat of solukioin o f thor-ium i n l e a d i s approximately 1 9 kcal,/mole and that ibs s o l u b i l i t y ai; GgO"C1 i s abou-i; 1.. 85 x lo--"m.f.

Pro tac t ;~ii_uti Stud-ies i n t h e H-;.&-Alpha Molg:S-ali Labora'~~o~. A nev glove-box f a c i l i t y. ., c a l l e d t h e High-Alpha Molten-SalC LaboratoiJ-, for s t u d i e s of p r o t a c biniun removal from rnol~ien f l u o r i d e mixtures %ms described i.n the previous progress r e p o r t . Experiments on extrac-Lion of protac-i;inj.uri from a brzeii-er-blanket mixLure, LLF-TliFr. (73-27 mole $), by .I.iquid-netal extraciion a t t h e t r a c e r I.evel ( f r a c t i o n of a p a r t pe-r b i l l i o n p a r t s o f 233Pa') are described lin 'clne secbion "Remciva!. o f Protactinium f r o m p o l ~ e nFluoride by Iic4uction processes" of t'nis repo.r*t. A s f m i l a i - experimznt with an i n i - t i a l concentration of about 25 p p m of 231Pa i n t h e mol-ten f i u o r i d e m i x t i x r ? w a s condGcier?, i n the i I i p ; h - A l p h NolLen-Salt Laboral;ory .Lo de tcrrnine whether a lo5 .i;riiiies higher pro+.ac... t i nlum concentra-'cion would result i n s i g n i f i c a n t d-i.ffercnces riil pro-kactinium behavior during e x t r a d i i o n and recovery experimenLs. R e s u l t s rep o r t e d here i n d i c a t e t h a t a 1.arge f r a c t i o n of t h e reduced pro5actini.um d.i_sappears from molten l e a d i n a t a i ? t a P d n coniainer, 7.n agreement wi-th the t r a c e r - l e v e l experiments, but one s a n p i c i i d i c a t e r i t h a - i ?7$ O F the protactinium remained after about 6 h r at 625°C. -___I_

I _ -

'i%e compl-eted. expe-rjment run 1-12, was conduc-Led i i i sev:.ral s tages, wtth -the flumace coolcil t o roon impera-Lure between s t a g e s . I n the f i r s t operation a 17 M - HI3 s o l u t i o n containing 9 mg of purified. '?'Pa was mfixed w i t h /+.O g of i r r a d i a t e d ThE4, conts::.nins aboui; 1. rnc of 233Pa* The s a l t was heated i.n a platinum d i s h t o evaporate water a i d BF, and t h e d r i e & rxixt-ure was added. t o a nickel. pol; c o n t a i n j n s 330

149

E X T R A C T I O N TIME !hr)

F i g . 5.10. Effect of Thorium Metal on t h e Extraction of " ' P a LiF-%%2-ThF4 ('73-2-25 Mole $1 i n Salt-Lead System at 600째C.

from

ORNL-DWG 66-971

3.0

600

550

T EM PE R A T URE ("C ) 500

450

400

;;

2.0

0 c

4.5

: t .o

QJ -

n 4

e LL

0.8 0.6

11 E

0.4

w V

s 0.2

Fig. 5.11. Temperature Dependence of t h e S o l u b i l i t y of Thorium in

Molten k a d .

150 of pretreaked- TJj.F-ThF4 (73-27 mole $). A copper A l t e r u n i t WRS placed i n 'c'ile p o t which was sealed, evacuated -io 450 IJ. pressure t h r e e times, and f i l l e d with helium each -time. The furnace was theii i i e a l x d . with h e l i u i f1owi.n.g through t h e pot under a sl.igh-t positi.ve p r e s s u r e . After reaching 60OoC, a mixture of HF and H2 w a s passed through t h e melt f o r 50 min t o convcr-t any oxide i m p u r i t i e s t o f l u o r i d e s , and t h e n t h e ncl.6 was t r e a k d with H2 for 4 h:r t o redii.ce N i E 2 , which r e s u l t e d :Prom t h e hyd-rofLuorina?;ioii, t o metal.lic n i c k e l . Apparently because o f a t o o high :I, Cl.ow r a t c , p a r t of the me2.t splashed up t o t h e -top of t h e PO-i, where it sol-i-d-ified. On attempting 1;o remove the fi-rst f i l t e l - e d m e l t sample, t h e copper f i l t e r w a s torn loose from t h e 1/8.-in. n i c k e l -tubi.ng t o which it was atkached, and t h e copper f i l t e i - fe1.l. back in'co t h e melt. A f t e r cooling, t h e cake a t t h e top of t h e m l t was broken up, a 1.0-g sample was taken, t h e remaind-er of -the m a t e r i a l w a s return3d t o t h e pot, and. tile HF-H;! treatment oi" t h e melt w a s repeatcd. No difficu1.t)- due t o t h e copper f i l - t e r i n -t'rie nlel~twas observed.

I n the second stage, t h e pot containing t h e t r e a t e d Li@'-ThFLF mixture was connected. t o a s i m i l a r pot l i n e d with tarria1.um 2nd cot-!..-of Pb-'i'h a3L.oy t h a t had. been saLurated with thorium a t t a i n i n g 692 600째C. The molten s a l t was t r a n s f e r r a d t o t h e tantal.imi-lI_inedpot a t 655째C through a transfei- l.inz at 600째C by a p p l i c a t i o n of 10 1.b of helium pressure t o -Hie sa1.t p o t . Previous e f f o r t s t o effect sa.l'c t r a n s f e r had been f r u s t r a t e d by low temperatures i n t h e - t r a n s f e r l i n e resi&ting from the high ver%ical temperature g r a d i e n t above the fu.mace block, whlch w a s metnioned i n t h e previous r e p o r t . 2 4 A coil-ed h e a k z r above t h e block and b e t t e r insu1a'i;ion a t -i;lic fl.oor l e v e l 07 t h e glove box overt h i s problem. A f t e r the t m n s f e r w a s completed, helium sparztng was used t o cause m3.xi.ng of -the l e a d and s a l t phases. The spargiiig w a s rintermpted a t i n t e r v a l s t o permit phase separatton. Ssjnrpl-es o f t h e s a l t phase were remove& with copper r i l t e r u n i t s , and samples of t h e m e t a l phase were no-mally removed with s i n t e r e d s t a i r i l e s s s t e e l f i L t e r u n i t s . Measurements of t h e total. gamma a c t i v i t y of 1-s p o r t i o n s of t h e s a l t samples a f t z r recovery from t h e f i l - L e r u n i t s showed t h a t t h e protactinium content of t h e salt phase was decreasing sl.or.rly a f t e r a.bout 2 h r contact time 'netween s a l t and metal phases. A t -tints time, 5 .O g of thoriurn-metal t u r n i n g s was added t o t h e mixture; s a m p l i n s o f the two phases 75 min l a t e r showed a sharp decrease i n Llie gross g-a,nuia. act;ivi.ty of -the s a l t phase wi-thout a conseqi.1ent increase i n .tile act;i.vity of %he sta3.nless s t e e l sampler and. t h e i r contained lead-phase sample A f'urtl-icr 3-hr con-Lact time f a i l e d t o produce a s i g n i f i c a n t change i n -the a c t i v i t y of t h e 3amp1-e~wtth one exceptrion: a san1pl.e o f the metal phase inadverten-tly o b t a i n r d i n a copper sampl-er shoved H si-gnificaiitly ' ; P a anal.yses, t'naa t h e higher actT%<.'i;yl e v e l , 1.ater coLifime51 by " s'caiiiless steel. ffi.ltered sampks taken before and a t t e r t h c copper samples. The f i r n a c e w a s t h e n allowed t o c o o l t o room temperature. e

Fina?l..y, t h e l e a d phase w a s t r a r t s f e r r e d 'LO an unlined n?:.ckeJ. pot con'caini_.ng LiF-.'l'hFl, of t h e same composition used previoiis1.y but without protactinium., A mixture of hyr3rogen and snhycirous :IF w a s bubbled t'nrough t h e lead and s a l t phases i n an e f f o r t t o convert me-tal-1.i-c proLa,ctinri.um i n t h e l e a d to PaF4 and t r a n s f e r i t to the sal..-Lphase. Time lirnitatj-oas preven-Led a thorough test of t h i s procedure.

151 D a L a obtained i n t h e above-described experiment, run 1-12, a r e s h a m i n Table 5.9. The gross gama values were obtained by weighing a sample, usually 1.000 0.002 g, p l a c i q it i n a s m a l l g l a s s vial, seali n g t h e vial i n a p l a s t i c envelope as i t was jxmoved from .the glove box, and t h e n p l a c i n g t h e envelope o v e r a sodium iodide c r y s t a l tlnat was c(xmected -to an KIDL s c a l e r . These samples .were t h e n s e n t â&#x201A;Źor s o l u t i o n and. analysis by t h e alpha-pulse-height niethod t o dete.mine their a31Pa content. The whole metal samples were counted f o r gross gamma a c t i v i t y i n a similar manner. The s t a i r d e s s s t e e l samplers and t h e i r lead conbents were d i s s o l v e d s e p a r a t e l y , and 231Pa analyses %reremade on t h e s o l u t i o n s ; b u t t h e copper s<anpl.erw a s d i s s o l v e d along w - i t h t h e lead sample t h a t it contained. Tke m o u n t of lead i n each sampler w a s a l s o d e t e -nnined L

The data i n Table 5.9 confirm t h e conclusion, based on e a r l i e r experiments wLth t r a c e r concentrations of " ' F a ( s e e ''Rernov-d. o f P r o t actiniutn from Molten Fluorid.es by Oxide P r e c i p i t a t i o n , " t h i s r e p o r t ) -t,hat pro-tactinilnro. f l u o r i d e i s reduced t o the me-Lallic s t a t e by thorium d i s s o l v e 3 i n l.ead. It, f b r t h e r appears that most of t h e protactinium does n o t s k y d i s s o l v e d i n t h e l e a d phase long enough t o pe-m.it t r a n s f e r of the l e a d to another c o n t a i n e r f o r recovery 07 t h e protactinium by h ~ i d r o f l ~ ~ o r i ~ i a t i b. ount , a m a l l f m c t i o i i of t h e protac-ti:nim w a s app a r e n t l y recovered. i n this fashion.

The variable concentration of protactinium ia t h e lead, small i n all. cases as compared with the atniount i n t h e s t a i n l e s s steel samplers,

Table 5.9.

Run 1-12:

Equi.libratiori oi' LiF-ThFA

(73-27Mole $ ) with Pb-Th Alloy a t 600Â°C Sample

Zi1i-Lii3l

8.5

sadt

I,ead., 34-rnin con- act (ss)

0.4

S a l t , .!j?-rrlin contact ( 6 s )

4.4

Leati, 84-min coiitact ( s s )

0.09

~u:i.t, IlO-niin c o n t a c t (ss)

4.2

Sal:L,

0.07

216-rrcin c o r i t w t

Lead, 251-min conl;ac:-t :r,ea.d,

(mi added)

(ss)

3Lbl-mi.n contact (copper)

~ e a d ,359-min c o n t a c t (3s)

Sa:Lt, 4tO4-n~i.nc o n t a c t ( s s )

0.07 1..46

0.08 0.08

15% mzy i n d i c a k t h a t t h e tendency of protac’iiii5.um t o absorb on, o r a l l o y with, i r o n causes t h e protactiniurn to be remo.ved. from t h e l e a d samp1.e dii-ring i t s passage through the s k t e r e d s t a i n l e s s s t e e l f i l t e i - material.. A n e f f o r t w a s made t o remove any protactinium-containi.ng ma’ieri-a1 adhering to t h e ou.tside wall of t h e samplers a f t e r they cooled t o room tempera-Lure p r i o r t o a n a l y s i s . They were scraped and a l s o given an acid treatment before t h e y were dissolved. It i s not clcar, a t p r e s e n t , why -the lead-contai-ning copper sampler showed a much higher protactinlwn content than t h e samples ob’iained. with s t a i - n l k s s s t e e l samplers, but it seems s i g n i f i c a n t -that thi.s sample i n d i c a t e d t h a t 17% of the prot a c t i n i u m remained i n t h e lead a . f t e r almost 6 h r i.n conLa.ct with i;ant;alwn at 625°C. The t r a n s f e r OS a small f r a c t i o n o f t h e protactinium from t h e lead. phase t o a m o l t e n f l u o r i d e mixture by HF trea-tieTlt, as ind.icated by preliminary resul-ts, ris encouraging, but means of prevenbing loss of’ the major part o f t h e protactinium by adsorption on oi: al-loying wLth c o n t a i n e r w a l l s or o t h e r rnaterial.s obv.i.ously w i l l be sought rin continui n g ezperiiiierits. Radiation Chemi st ry

I -

Design, development, and. f a b r i c a t i o n of t h e i n - p i l e molten-sa1.t expeyhient continued. Mod.ifica,tions Lo beam hole HN-1 i n t h e OIUt and i n s t a l l a t i o n of experLmental. equipment a r e scheduled t o begin e a r l y i n April, and i n - p i l e operation of t h e T i l - s t i r r a d i a t i o n experiment will begin i n June 1966.

Auxiliary equipment needed t o modify beam hole HN-1.f o r the moltensal..t experimenLs has been fabricated.. ‘Ilhis equipment consists of (1)a new al.iminum beam-hole l i n e r , ( 2 ) a beam-hole extension sl-eeve, and ( 3 ) an equipment chamber, l o c a t e d st t h e face of t h e Ireactor shielding, which w i l l contain tanks and valvec, required t o remove s a l t samples and a d d . makeup s a l t t o t h e autoclave, during i n - p i l e operation.

Component p a r t s of t h e experiment package which haw been f a b r i c a t e d a r e t h e s h i e l d pl~u.g, the l o o p c o n t a i n e r can, and. t b z connector, as shown i n Fig. 5.12. All corflponeilt p a r t s of .the thermal l o o p have been f a b r i c a t e d and a r e being assembled-. A photograph of t h e p a r t i a l l y assembled thermal-loop expzrimeiit i s shown i n Fig. 5.13. The 12-ft-long sample l i n e with e3.ectri.c h e a t i n g elements, which a r e bonded t o t h e sa.mp1.e l i n e by means of nickel metal spray, has also been completed along with t h e main loop-hester-cooler u n i t . T%e h e a t e r - c o o l e r - u n i t d e s i p , previously described, 2 5 h a s beei? changed by s u b s t i t u t i r i g cooli n g tubes of Zircaloy-2 i n s t e a d of s t a i n l e s s s t e e l and Z i r c a l o y - 2 f o r t h e heatey-cooler jackei; i n Lieu of g r a p h i t e . This change w a s made .to reduce t h e attenua-tlioii of neutron flux and t o prov5.de f o r Lmprovements t n t h e e f f f c i e n c y and o p e r a t i o n a l f l e x i b i l i t y of t h e heater-cool e r unri i; by using a Z i r c a l o y - 2 metal-sprayi.ng -teclinjque t o a t t a c h t h e heatei.s and. co01in.g coils *

153 PHOTO 1306OA

CONTAINER

CAN

CONNECTOR

SHIELD PLUG

F i g . 5.12. S h i e l d Plug, Container Can, and Connector f o r I n - P i l e Molt en- S a l t Loop.

HOUT .ER

I-

Fig. 5.13.

P a r t i a l l y Assembled I n - P i l e Molten-Salt-Loop Experiment.

154 The instrument and c o n t r o l p a n e l s are being f a b r i c a t e d i n t h e I n s t r u m e n t a t i o n and Controls D i v i s i o n shops and a r e approximately 6% complete. The instrument p a n e l s are t o be set i n p l a c e i n f r o n t of beam h o l e HN-1 i n A p r i l . Development and E v a l u a t i o n of Methods f o r t h e Analysis of t h e MSRE Fuel Determination of Oxide i n MSRE Fuel The study26 of h y d r o f l u o r i n a t i o n a s a way t o determine oxide i n MSHE s a l t s was continued. This method27 i s based on t h e r e a c t i o n 02-

W F ( g ) S . H 2 0 ( g ) + 2F-

which occurs when a m o l t e n - s a l t sample i s purged with an H2-HF g a s mixture. The amount of water evolved i s t a k e n a s a measure of t h e q u a n t i t y of oxide i n t h e m o l t e n - s a l t sample. Data have been r e p o r t e d p r e v i o u s l y 2 7 f o r t h e Karl F i s c h e r t i t r a t i o n of t h e water evolved from s t a n d a r d a d d i t i o n s of Z r O 2 and U02 t o a 50-g f â&#x20AC;&#x2122; u e l m e l t . Figure 5.14 i s a schematic flow diagram of t h e h y d r o f l u o r i n a t i o n a p p a r a t u s now being used. Since it would be d i f f i c u l t t o perform t h e Karl F i s c h e r t i t r a t i o n i n t h e h o t c e l l , a P205 water e l e c t r o l y s i s c e l l (Beckmann moisture-monitor c e l l with rhodium e l e c t r o d e s ) was i n s t a l l e d i n a component t e s t f a c i l i t y t o monitor t h e e f f l u e n t - g a s stream from t h e h y d r o f l u o r i n a t o r f o r water.

To e s t a b l i s h t h e c o n d i t i o n s necessary t o use t h e e l e c t r o l y s i s c e l l a s a water monitor, Z r O 2 samples were added t o 50 g of MSRE f u e l i n t h e h y d r o f l u o r i n a t o r . Because t h e r e i s a maximum r a t e of water e l e c t r o l y s i s beyond which t h e c e l l may be damaged, it w a s necessary t o s p l i t t h e e f f l u e n t - g a s stream and t o p a s s only a p o r t i o n of it through t h e c e l l . A f t e r t h e optimwn g a s p r e s s u r e s and flow r a t e s were e s t a b l i s h e d , t h e results given i n Table 5.10 were obtained. Figure 5.15 i s a recording of t h e water evolved from two s t a n d a r d a d d i t i o n s of ZrO;! t o a f u e l sample. The f i r s t two peaks of each recordi n g r e s u l t from atmospheric contaminants introduced during l o a d i n g of t h e Zr02 i n t o t h e f i e 1 sample and removal of contamination from t h e i n t e r n a l metal s u r f a c e s of t h e apparatus. A f t e r t h e fuel-Zr02 sample was melted, it was purged with H2-HF a t 625Â°C t o evolve t h e oxide. The p l a t e a u of t h e curve f o r t h e 139-mg Z r O 2 a d d i t i o n a p p a r e n t l y ref l e c t s t h e l i m i t o f s o l u b i l i t y of Z r O 2 i n t h e melt.

Also, a n a l y s e s were made on -50-g p o r t i o n s sampled from 6 kg of simulated molten MSHE f i e 1 of unknown oxide c o n c e n t r a t i o n . These samples were t a k e n i n copper l a d l e s , cooled t o room temperature, and t h e n t r a n s f e r r e d t o t h e h y d r o f l u o r i n a t o r under an i n e r t atmosphere. Three of t h e samples were exposed t o t h e atmosphere, s i n c e t h e samples from t h e r e a c t o r w i l l be exposed while being t r a n s f e r r e d t o t h e h y d r o f l u o r i n a t o r . The sample l a d l e was s e a l e d i n t h e h y d r o f l u o r i n a t o r with a d e l i v e r y tube spring-loaded a g a i n s t t h e s u r f a c e of t h e s a l t (Fig. 5.14). An

155 OHNL -hWG

65 -8855A

HYDRCFL.IJORI NAlCiR

F i g . 5.14, Schematic Flow Diagram of %he Apparatus f o r t h e Determin a t i o n of Oxide i n MSRE Fuel by Hydrofluorination. Table 5.10. Recovery of Oxide f r o m Standard Additions of Z r O a to MSKE Fbel

Effluent GB s Passed Through Cell

(4) 10

~ r 0 2 (ing)

Taken

Found

18.6 25.6 25.8

18.3

72.2

72.6

131.0

135.0

139.0 4

26.0 27.1

134..8

136.5

140.0

Recovery ($)

98.6

101.6 1-04.9

100.5

102.9

101.1

100.7

156 ORNL-DWG 6 6 - 4 0 3 8

75 H2 FLOW, 200 cc/rnin

I-iF, 0.2 atrri

SALT M E L T , 50 g

(100 7 YO RCCOVERED)

ti'

-i 45 t-

111

1 lL

LL Id

Z r 0 2 LOADED

HF INTRODUCED

+SAL;

MELTED

IO0

TIME (mini

Fig 5.1-5. Determination of Standard Additions of Oxide in Simul a t e d b E X 3 Fuel by Hydrofluorination.

Table 5.11.

Precision o f D e t c m l n a t i o n of Oxide i.a

Molten Simulated MSRE Fuel Sample Nimbe r

Oxride (ppm)

350 345 3/!0

340 375&

360" r ~ 0 5 ~ ?Exposed t o atmosphere f o r a t 1 e a : ; t 24 h r . 'Exposed

t o atmosphei-e f o r two weeks.

157 i n i t i a l purge with H2-RF was made a t a tenrperature below t h e iiielting p o i n t t o remove oxide from the metal s u r f a c e s and oxide contamination i'rom t h e s-urface of t h e s a l t . With f b r t h e r temperature i n c r e a s e , the d e l i v e r y tube vas d r i v e n below t h e s u r f a c e of Yne s a l t a s it melted t o sparge t h e melt w i t h H2-HF. Table 5.11 l i s t s t h e r e s u l t s .

W e must here c o n s i d e r whether Ynese r e s u l t s r e p r e s e n t a q u a n t i t a t i v e removal of oxide o r simply a re-turn t o an o r i g i n a l e c ~ u i l i b r i w nbase l i n e . It may be seen by rearranging t h e equ-ilibrium expression f o r t h e r e a c t i o n of oxide with HF t h a t Lf t h e p r o p o r t i o n of HF reagent i n t h e purge g a s i s increased, t h e residual-oxide c o n c e n t r a t i o n w i l l be reduced:

[02-] = (P~,~/P&) 'x c o n s t a n t

Because t h e HF reagent c o n t a i n s t r a c e s of w x k r , t h e IIF c o n c e n t r a t i o n i n t h e i n f l u e n t cannot be lncreased independently. However, i f t h e coneent r a t i o n s of ILF and â&#x201A;Ź120 i n t h e purge g a s a r e doubled, t h e r e s i d u a l oxide i n t h e melt should be reduced by a f a c t o r of 2. Wlien t h e p r e s s u r e o f HF i n t h e sparge g a s through -terminal (oxide-depleted) melts was doubled, no a d d i t i o n a l w a t e r was obtained. Also, e q u i l i b r i u m c o n s t a n t s a r e kernp e r a t u r e dependent, and no a d d i t i o n a l peaks were observed with temperature v a r i a t i o n s of 200Â°C on d e p l e t e d m e l t s .

Samples of f l u s h and. -he1 salt taken during t h e December s t a r t u p of t h e r e a c t o r were analyzed f o r oxide i n a component -Lest f a c i l i t y . Table 5.12 swnmarizes t h e r e s u l t s . Figure 5.16 i s a recording of t h e water evolved from t h e f i r s t h i e l - s a l t sample taken a f t e r t h e rue1 w a s loaded i n t o -the r e a c t o r . The r e s u l t s of t h e a n a l y s e s by t h e h y d r o f l u o r i n a t i o n method were i n good agreement with t h o s e by t h e KBrFh procedure28 (Fig. 5.17). The KBrF4 values p a r a l l e l e d t h e t r e n d s shown by t h e h y d r o f l u o r i n a t i o n Table 5.12.

Sample

Oxide Concentrations of n u s h and Fuel Salt; from t h e MSR

Time of S a l t C i r c u l a t i o n (hr) ~~

Flush s a l t

.Fuel s a l t

Oxide Concentration (PPn1)

24.7

29.1

47. G

106

3.4

120

23.8

105

32.2

52.5

158 method, but averaged s l i g h t l y higher. This b i a s was n o t unexpected, s i n c e t h e p u l v e r i z e d samples required- f o r t h e KBrF4 method. a r e e a s i l y contamlnated by atmospheric moisture. The apparatus ( F i g 5.18) designed. for Yi?e deterrrlination, i n t h e h o t c e l l , of t h e oxide 7-n h i g h l y radioa.ctive f’uel. samples i s f’unctionally i d e n t i c a l - with t h e compoilents -Lest f a c i - l i t y used f o r t h e analyses rep o r t e d above. Figure 5.18 shows t h e h y d r o f l u o r i n a t o r positioned. i n t h e f’urnace, which i s exi;ernal_ t o t h e valve compartment. The h y d r o f l u o r i ORNL- DWG 6 6 - 4 0 2 8 A

He FLOW, 200 cc/min dF, 0 2 a t m FUEL SALT, 4 8 . 7 9

400

TIME (min)

F i g . 5.16. Determination of Oxids i n MSR F u e l Sample E’P4-11 by Hydrofluorination.

ORNL-DWG

66-2026A

250

-E

,”

200

150

100

Fig. 5.17. Results of Hydrofluorination and KBrFr, Analyses f o r Oxide in Flush and N e 1 S a l t s During December StarLup of the MSR.

159

7 P HO TU 82 177

Fig. 5.18.

Hot-Cell Apparatus.

160 n a t o r i s p u t on stream through O-ring b a l l j o i n t s t h a t a r e closed or opened by a remotely operated argon-actuated a i r p i s t o n . The valve compartment c o n t a i n s t h e sodium f l u o r i d e t r a p , t h e c a p i l l a r y water s p l i t t e r , t h e PzO5 water e l e c t r o l y s i s c e l l , and t h e soda-lime t r a p f o r cleaning t h e e f f l u e n t g a s stream. These components a r e shown i n Fig. 5.19, where t h e cover p l a t e h a s been removed. The modular c o n s t r u c t i o n was chosen i n hopes t h a t any maintenance necessary can be performed remotely. If n o t , any component can be removed manually i n 2 t o 5 min i f t h e h o t c e l l i s s u f f i c i e n t l y decontaminated. Figure 5.20 shows t h e disassembled h y d r o f l u o r i n a t o r . The copper sample l a d l e i s contained i n t h e n i c k e l l i n e r , which f i t s i n t o t h e bottom of t h e h y d r o f l u o r i n a t o r . The b a f f l e s on t h e spring-loaded sparge tube f i t i n s i d e t h e l i n e r and confine t h e molten s a l t t o t h e l i n e r during t h e bubbling o p e r a t i o n of t h e a n a l y s i s . This arrangement allows t h e s o l i d sample, a f t e r a n a l y s i s , t o be removed from t h e bottom of t h e h y d r o f l u o r i n a t o r and t h e n t o be disconnected a t t h e Swagelock f i t t i n g

F i g . 5.19.

Top View of Valve Compartment of Hot-Cell Apparatus.

161 PHOTO 82187

Fig. 5.20.

Disassembled Hydrofluorinator.

162 and d i s c a r d e d along with t h e l a d l e , l i n e r , and bottom of t h e sparge tube. This d e s i g n a f f o r d s considerable saving i n c o s t p e r a n a l y s i s , because it p e r m i t s t h e r e p e a t e d use of t h e complete h y d r o f l u o r i n a t o r . Figure 5.21 shows t h e H2-HF mixer s e c t i o n , which i s l o c a t e d i n t h e a c c e s s a r e a behind t h e h o t c e l l . The HF p r e s s u r e i s r e g u l a t e d by cont r o l l i n g t h e temperature of t h e HF t a n k shown a t t h e l e f t . The flow rates of t h e H2 and HF a r e c o n t r o l l e d by n i c k e l and platinum c a p i l l a r i e s r e s p e c t i v e l y . T h i s apparatus a l s o c o n t a i n s s a f e t y i n t e r l o c k s and l i m i t i n g c a p i l l a r i e s t o prevent r e l e a s e of HF and excessive p r e s s u r e s i n s i d e the hot c e l l . Figure 5.22 shows t h e master c o n t r o l panel, which i s l o c a t e d i n f r o n t of t h e h o t c e l l . This p a n e l c o n t a i n s t h e moisture r e c o r d e r ( n o t shown), helium and hydrogen p r e s s u r e c o n t r o l s , HF c o n t r o l switch, hydrof l u o r i n a t o r c o u p l e r switch, temperature recorder, furnace power c o n t r o l s , and power c o n t r o l for t h e c o u p l e r - l i n e h e a t e r .

A f t e r t h e y were f a b r i c a t e d , t h e apparatus and a u x i l i a r y equipment were assembled i n t h e h o t - c e l l mockup, and a l l mechanical o p e r a t i o n s were performed s u c c e s s f u l l y with Master Slave manipulators. The equipment w a s t h e n t r a n s f e r r e d t o t h e l a b o r a t o r y and w a s assembled on t h e bench t o p for t r i a l a n a l y s e s of samples. I n d i v i d u a l components were t e s t e d e x h a u s t i v e l y and, when necessary, were modified or r e p l a c e d t o o b t a i n maximum d e p e n d a b i l i t y and t o minimize h o t - c e l l maintenance. A f i n a l check of t h e s p l i t t e r and c e l l w a s made by i n j e c t i n g a known q u a n t i t y of water i n t o t h e flow system; q u a n t i t a t i v e recovery of t h e water r e s u l t e d . The e n t i r e system was t h e n checked out by analyzi n g f u e l - s a l t samples. S a t i s f a c t o r y r e s u l t s w e r e obtained.

The equipment i s now being t r a n s f e r r e d t o t h e h o t c e l l and i n s t a l l e d therein. Voltammetric Determination of I o n i c I r o n and Nickel i n Molten MSRF, Fbel

By c o n t r o l l e d - p o t e n t i a l voltammetry, Fe2+ and N i 2 + were determined i n a 100-g sample of MSRE fuel. The sample was withdrawn from t h e r e a c t o r i n e n r i c h e r ladles and was t r a n s f e r r e d under an i n e r t atmosphere t o t h e g r a p h i t e c r u c i b l e of an e l e c t r o c h e m i c a l c e l l assembly f o r remelti n g and a n a l y s i s . The c e l l assembly and e l e c t r o d e s developed f o r e l e c t r o c h e m i c a l s t u d i e s of molten-fluoride s a l t s a r e d e s c r i b e d e l s e ~ h e r e . ~ ' - ~The I i r o n and n i c k e l i n t h e molten f u e l a r e suspected t o be i n t h e m e t a l l i c s t a t e , as w e l l a s i n t h e form of s o l u b l e i o n i c s p e c i e s . However, only i n t h e d i v a l e n t o x i d a t i o n s t a t e a r e t h e s e metals e l e c t r o r e d u c i b l e i n t h e melt and can t h u s g i v e voltammetric r e d u c t i o n waves. By voltammetry and by t h e s t a n d a r d - a d d i t i o n technique, t h e c o n c e n t r a t i o n of Fe2+ was determined to be -10 pprn. The c o n c e n t r a t i o n of N i 2 + was below t h e l i m i t of d e t e c t i o n by voltammetry (<1 ppm). Average t o t a l c o n c e n t r a t i o n s of i r o n and n i c k e l , determined by conventional methods, a r e about 125 and 45 ppm r e s p e c t i v e l y . Thus it appears t h a t most of t h e i r o n and n i c k e l i n t h e f u e l i s p r e s e n t i n t h e m e t a l l i c s t a t e , probably a s f i n e l y divided p a r t i c l e s .

163

Fig. 5.21. H2-HF Mixer Section of Hydrofluorinator Apparatus.

164

Fig. 5.22. Main Control Panel of Hydrofluorination Apparatus.

165 Chromium concentration, determined conventionally, i s -50 ppm. I n t e r f e r e n c e from uranium prevents t h e voltammetric determination of chromium i n t h e molten s a l t . A well-defined wave w a s observed t h a t Possibly, t h i s wave can corresponds t o t h e reduction U ( 1 V ) - + U ( I I I ) . be used t o continuously monitor uranium i n t h e system; more work i s contemplated i n t h i s a r e a . Development and Evaluation of Equipment and Procedures f o r Analyzing Radioactive MSRE S a l t Samples A s s t a t e d e a r l i e r , 3 2 s t a t i s t i c a l e v a l u a t i o n of t h e c o n t r o l d a t a i n d i c a t e d t h a t a negative b i a s of approximately 0.8% e x i s t e d i n t h e coulometric uranium r e s u l t s . The uranium procedure c o n s i s t e d p r i m a r i l y of s i x s t e p s . 1. Determination of blank. 2. P r e p a r a t i o n of sample. 3. Prereduction of sample a t +0.125 v vs S.C.E. 4. Reduction of uranium and copper a t -0.325 v vs S.C.E. 5. Oxidation of copper a t +0.125 v vs S.C.E. 6. C a l c u l a t i o n .

I n s t e p s 1, 3, 4 , and 5, t h e t i t r a t i o n w a s allowed t o proceed u n t i l t h e c e l l c u r r e n t had decreased t o 5 pa. The c a l c u l a t i o n w a s performed using t h e following formula:

[(A - B) - C - (bt/E)]DE where

micrograms of uranium p e r t e s t s o l u t i o n

A = readout voltage f o r uranium and copper reduction i n m i l l i v o l t s , B = blank of e l e c t r o l y t e i n m i l l i v o l t s , C = readout voltage f o r copper o x i d a t i o n i n m i l l i v o l t s , pg of uranium p e r microcoulomb, D = 1.233 x E = coulometer c a l i b r a t i o n constant f o r 10-microequivalent range i n microcoulombs p e r m i l l i v o l t , b = background c u r r e n t i n microamperes ( 5 pa), t = time of uranium and copper reduction i n seconds.

I n an attempt t o e l i m i n a t e t h e b i a s , s t e p s 1, 4 , and 6 were modified. The determination of t h e blank w a s eliminated. The c u t o f f p o i n t for t h e uraniun and copper r e d u c t i o n w a s changed from 5 pa t o 50 pa. A n X-Y r e c o r d e r (Fig. 5.23) w a s a t t a c h e d t o t h e coulometer t o monitor t h e t i t r a t i o n s . When t h e readout v o l t a g e and c e l l c u r r e n t were p l o t t e d on t h e X and Y s c a l e s , r e s p e c t i v e l y , a s t r a i g h t l i n e with a negative slope w a s obtained a f t e r t h e recorder pen had reached a maximum Y value. By e x t r a p o l a t i o n of t h e curve (Fig. 5 . 2 4 ) , it w a s p o s s i b l e t o o b t a i n t h e readout voltage corresponding t o a c e l l curr e n t of 0 amp. Due t o t h e e r r o r introduced by t h i s technique, a potent i o m e t e r w a s connected t o t h e i n t e g r a t o r c i r c u i t of t h e coulometer i n order t o o b t a i n more p r e c i s e readout v o l t a g e s . This n e c e s s i t a t e d terminating t h e t i t r a t i o n s a t a s p e c i f i c end p o i n t . A c e l l c u r r e n t of

166

1 I

F i g . 5.23.

High-Sensitivity Coulometric Uranium Apparatus.

found e m p i r i c a l l y t o be e coulometer w a s automati

ct iea1 p o i n t of t e mi na o f f when t h e ammeter d a c e l l c u r r e n t of 50 pa. A t t h i s p o i n t , t h e ti , This p o r t i o n of t h e readout vol er; t h e remain 50 t o 0 pa an expanded c e l l current vs gs were combined t o nd copper reduction. Based on more than 200 t i t r a t i o by t h e e x t r a p o l a t e d PO

t e s t s o l u t i o n t h e n became

[(A - B) where

CIDE

= micrograms

of uranium p e r t e s t s o l u t i o n

out voltage f o r uranium copper reduct i n millivolts, for copper o ained by e x t r a p o l a t i o n of t h e c e l l c u r r e n t vs readout voltage curve from 50 t o 0 Pa), D = 1.233 x pg of uranium p e r microcoulomb, E = coulometer c a l i b r a t i o n const for 1 0 - m i c r o e q u i ~ l e n trange i n microcoulombs p e r m i l l i v o l t .

167 The uranium p r e s e n t i n t h e t e s t s o l u t i o n could be c a l c u l a t e d , s i n c e t h e v o l t a g e s read o u t on t h e potentiometer were p r o p o r t i o n a l t o t h e coulombs r e q u i r e d i n t h e r e d u c t i o n of u r a n i u m and copper and t h e o x i d a t i o n of copper. Sa.tn-ole Analvse s

@om December 16, 1965, through January 26, 1966, s i x f l u s h - s a l t and twenty-two f u e l - s a l t samples were r e c e i v e d i n t h e High-RadiationLevel A n a l y t i c a l Laboratory. All 28 samples were analyzed f o r U, Zr, ORNL-DWG

66-4784

G 5 E

[L [L

24 _1

-1

w V

0.1

F i g . 5.24.

0.2

0.3

VOLTAGE

0.4

0.5

C e l l Current vs Readout Voltage Curve.

0.6

168

--r ORNL-DWG

1.9

I .6

-+ 0

E 1.2

z W

66-'

0.8

W V

0.4

EXTRAPOLATE VOLTAGE

POTENTIOMETER VOLTAGE

0.1

0.2

0.3

VOLTAGE

Fig. 5.25.

0.4

0.5

A Portion of t h e C e l l Current vs Readout Voltage Curve.

C r , Be, F, Fe, and N i . A l l s i x f l u s h - s a l t samples and t h e f i r s t twelve f u e l - s a l t samples received were analyzed f o r molybdenum.

Q u a l i t y Control Program The q u a l i t y c o n t r o l program i n i t i a t e d p r i o r t o p r e c r i t i c a l sampling was continued during t h e p a s t period. S y n t h e t i c s o l u t i o n s s i m i l a r t o d i s s o l v e d nonradioactive f u e l - s a l t samples were analyzed along with each f l u s h - s a l t and f u e l - s a l t sample. Due t o t h e r e l a t i v e l y small number of samples analyzed t o d a t e , t h e accumulated c o n t r o l d a t a i s i n s u f f i c i e n t t o c a l c u l a t e t h e t r u e p e r c e n t s t a n d a r d d e v i a t i o n s of t h e methods. The values shown i n Table 5.13 were obtained during t h e f o u r t h q u a r t e r of 1965. The 2s and average values shown were obtained by four d i f f e r e n t groups of s h i f t personnel. Molybdenum values a r e not shown i n t h e t a b l e since it was not added t o t h e s y n t h e t i c s o l u t i o n . The n i c k e l values i n d i c a t e t h a t a p o s i t i v e b i a s e x i s t s i n t h e method. The values given f o r t h e coulometric uranium procedure i n d i c a t e t h a t t h e negative b i a s was e l i m i n a t e d .

169

Table 5.13. Determination

C o u l anetr i c uranium

,hperometric, zirconium

Shift

Colorimetric nickel

NeuLron a c t i v a t ion, beryl-liuni

Added

(pg/ml)

19 40 30 34

A B

26 6 14 0

1117 1117 1117

22 16

1.1

C D

Colorimetric, i-ron

Number of Determinations

A B

Amperometric, chromium

Control Program, Fourth Q u a r t e r of 1965

R C D

8 5

656.6 656.6 656 6 656.6

.8 11.8 11.8

11.8

Average Value Found ( Y g m)

25 Percentage

658

1.11 1.55 0.57 0.99

1122 1077

7.27 13.53 5.1'1

656 659 658

1119

12.202 12.278 12.520 12.270

9.15 1.1.06 16.$4 14.38

A B C D

18 10 1.6

6.36 6.36 6.36 6.16

6.286 6.355 6.302 4.253

2.36 1.0.91 5.51 2.40

C D

16 10 18 0

6.08 6.08 6.08

6 713 6.748 6.669

3.92 6.24 14.32

A B C

3 0 2

847

853

1.08

847 847

849 856

1.. 83

1.48

170 References 1. MSli Program Semiann. Progr. Rept. J u l y 31, 1964, OIWL-3708, p. 321. 2,

See "Development and. Evaluation o f Equipment and Procedures f o r Analyzing Radioactive MSFE S a l t Samples," t h i s r e p o r t .

3. MSR Program Semia-m. Progr. Repl;. A x . 3l, 1965, Om-3872, p . 117. 4. See "Voltammetric Determination of I o n i c Iron auld Nickel. i n Molter1 KSRE F u e l ,

5. 6.

t h i s report.

MSR Program Semiann. Progr. Rept. Aug. 31, 1965, ORNL-3872, p. 140. See "Oxide Solubi.1i.ties i n MSm Flush Salt, Fuel S a l t , and Their Mixture s " t h i s r e p o r t .

MSR Program Semiann. Progr. Sept,. h e ; . 31, 1965, ORNL-3872, pp. 123-25.

K. A. Sense et a l . , J. Phys. Chem. 56, 223 (195L+)-

K. A. Sense and 13. W. Stone, J . Phys. &em. 62, 1411 (1958).

10. S. Can-Lor, Reactor Chem. Div. Ann. Progr. Rept. Dee. 31, 3..965, OFXL-3913, pp. 27-29,

11"

S. Cantor, Reactor Chem. Div. OKTJTJ-3262, pp. 38-41.

1.2.

E. A. Brown and R. P o r t e r , U. S. Bur. Mines Rept. I n v e s t . 6500 (1964).

13.

P. W. Bridgman, Proc. Am. Acad. A r t s S e i . 59, 3.62 (1923).

h i .

Progr. Rept. Jan. 31, 1962,

14. MSR Program Seniiann. Progr, Rept. Feb. 28, 1965, OWL-3812, pp. 12938.

15. MSR Program Semiarin. P r o p . Rept. Aug. 31, 1965, ORNL-3872, p . 152. 16.

m.,pp.

140-43.

2 (Ser. 2 ) , 329 (1913) (and sihseqinent 17. I. Langrnuir, Phys. Rev. papers).

18. 3eacto-r Chem. Div. Ann. Progr. Rept. Jan. 31, 1965, OEwT,-3789, pp. 59-62.

19.

20.

K. A. Sense an.d I?. W. Stone, J. Phys. Cheiii. 62, 96 (1958).

A. Buc'nl-er and J . L. S t a u f f e r , Symposium on Therumdynamics with Emphasis on Nuclear M a t e r i a l s and Atomic Transport i n Solids, Vienna, July 22-27, 1965, paper SM-66-26, p . 15.

21. 5. H. S h a f f e r e t sl., Nucl. S c i . Fng. 18, 177 (196L). I -

_ I

Reactor Chem. Div. A n n . Progr. Hept. Jan. 31, 1961, ORNL-3127, p. 8.

23.

Reactor Chem. Div. Ann. P r o p . Rept. Jan. 31, 1965, OHNL-3789, p . 56.

24.

MSR Program Semiann. Progr. Rept. Aug. 31., 1965, ORNL-3872, pp. 13741.

171 25.

MSR Pr0gra.m Semiam. P r o p . Rept. Aug. 31, 1965, 013KL-3872,p . 109, P i g . 5.2.

26.

MSR Progrrwn Semia.m. Progr. Rept. Aug. 31, 1965, OlWL-3872, p . 140.

27. 28. 29.

MSR Propmn Seniianii. Progr. Rept, Feb. 28, 1965, OHXI,-3812, p. 162.

G. Goldberg, A. S. Meyer, Jr., and J. C . Wnite, Ana,l.. Chem. 32, 314 (1960)

D . L. Manning, J . Electroanal. Chem, 6, 227 (1963). I

30. D. L. Manning and G. Mmnantov, J . E l e c t r o a n a l . Chem. r7, 102 (1.964). 31. I). L. Mannring, J . E l e c t r o a n a l . Cheui. 7, 302 (1964).

32. MSR Prograrri Semiam. Progr. Rept. Aiig. 31, 1965, ORNL-3872, p. 148.

172 6.

MOLTEN-SALT BHEEDER lXlQ%CTOK DESIGN STUDIES

Design and e v a l u a t i o n s t u d i e s have been made of thermal m o l t e n - s a l t b r e e d e r reac-bors (MSBR) in o r d e r t o assess t h e i r economic and nuclear pot e n t i a l and t o i d e n t i f y t h e inqortan-t desigii and devdopmeiit problems The r e f e r e n c e r e a c t o r design presentied here c o n t a i n s design problems r e l a t e d t o m o l t e n - s a l t reackors i n g e n e r a l .

The MSBR r e f e r e n c e design concept is a two-region, t w o - f l u i d system, f u e l s a l t s e p a r a t e d from t h e b l a n k e t s a l t by g r a p h i t e t u b e s . The fuel- s a l t c o n s i s t s of uranium f l u o r i d e d i s s o l v e d i n a mixture of l i t b i w n b e r y l l i u m f l u o r i d e s , while t h e b l a n k e t s a l t i s a i2toriurfl-lithium f l u o r i d e c o n t a i n i n g 27 mole $I thorium f l u o r i d e . The energy generated i n t h e r e a c t o r f l u i d i s t r a n s f e r r e d t o a secondary c o o l a n t - s a l t e i r c u i l ; , which cou-ples t h e r e a c t o r -Lo a s u p e r c r i - t i c a l steam c y c l e . On-site f l u o r i d e v o l a t i l i t y processing i s employed, l e a d i n g t o 1-ow u n i t processing costx and economic o p e r a t i o n as a thermal. breeder r e a c t o r . -*

L 7

NICII~

WBR P l a n t Design

F 1.o~ws he et Figure 6.1 g i v e s t h e flowsheet of t h e 1OOO-Mw ( e l e c t r i c a l ) MSER power p l a n t . F u e l flows through t h e r e a c t o r a t a, raLe o f about 4.4,OOO gpm ( v e l o c i t y of about 15 f p s ) , e n t e r i n g t h e c o r e a t 1000°F and l e a v i n g at 1300°F. The primary f u e l c i r c u i t has f o u r loops, each loop havi-ng a pump and a primary h e a t exchEnger. Each of t h e s e punips has a capackty of about 1.1..,00gpm. 0 The f o u r b l a n k e t - s a l t pumps and- h e a t exchangers, alt'nough smaller, a r e s i m i l a r t o corresponding components i n t h e fuelsystem. 'The b l a n k e t s a l t enteres the r e a c t o r v e s s e l a t 1.1.50"F and l e a v e s a t 1250°F. The b l a n k e t - s a l t pumps have a c a p a c i t y of about 2000 gym.

Four 14,000-gpi coolan-t pumps c i r c u l a t e tine sodium f l u o r o b o r a t e c o o l a n t s a l t , which e n t e r s t h e shell. s i d e of t h e primary h e a t exchanger a t 850°F and l e a v e s at 1.1..1.2'F. A f t e r l e a v i n g .t;h@ primary h e a t exchanger, bhe c o o l a n t salt i s f u r t h e r h e a t e d t o 1125'F on t h e s h e l l s i d e of t h e b l a n k e t - s a l t h e a t exchangers The cool.ant t h e n c i r c u l a t e s through t h e s h e l l s i d e of 16 once-through s u p e r h e a t e r s ( 4 s u p e r h e a t e r s p e r pump). I n a d d i t i o n , f o u r 20OO-,qm pwips c i r c u l a k a p o r t i o n of t h e cool-ant through. e i g h t r e h e a t e r s .

The steam systeiii flowsheet i s essential-2-y t h a t of t h e new TVA Bull Run p l a n t , w i t h modifications t o i n c r e a s e t h e rat.i.ng t o 1000 Mw ( e l e c t r i c a l ) and. t o p r e h e a t t h e working f l u i d t o 700°F p r i o r t o e n t e r i n s the

heat-exchange~superheater u n i t . A s u p e r c r i t i c a l power conversion s y s tem i s used, which i s a p p r o p r i a t e for molten-sal$ a p p l i c a t i o n a.:nd t a k e s advantage of t h e h i g h - s t r e n g t h s t r u c t u r a l a l l o y e - q l o y e d . U s e of a superc r i t i c a l f1ixi.d system r e s u l t s i n an o v e r a l l p l a n t l;hermal e f f i c i e n c y of ab out 45 $I

ORNL-DWG 66-4786

WE; BLANKET COOLANT STEAM

H,O

P h

----\06I b/ hr ~

psi0

Btu/:b

FREEZE VALVE

REACTOR VESSEL (I1

NET OUT?UT GROSS GENERATION BF SOOSIER PUMPS STATION AUXILIARIES REACTOR HEAT iNPUT NET HEAT SATE NET EFF:CiEVCY

1000 Mwe 1034 9 M w e 9 2 Mwe 25 7 Mwe 2225 M w t

7601 B t u l k w h r 44.9%

r - -- - - - - - - _ - - - _ _ _ - _ _ - -5.135* __ I

115185h 1000" F

10.067* 7.:52* - - - - -i - 8-

550p

i-----

2225 Mw: :

BLANKET SALT PUKOS(4 I 2000 gpm (NOMI EACH

____ ~

FUEL SALT

BLANKET SALT HEAT

F i g . 6.1. Flowsheet of YIBR Power Plar6t.

~ 1

174 Reactor Design F i g i x e 6.2 shows a p l a n view of %he MSBR c e l l arrangement. The r e a c t o r c e l l i s surrounded by f o u r s h i e l d e d c e l l s containing l;he superh e a t e r s and r e h e a t e r units; t h e s e c e l l s can be i n d i v i d u a l l y i s o l a t e d f o r maintenances The processing c e l l , I.ocated a d j a c e n t t o t h e r e a c t o r , i s d i v i d e d i n t o a h i g h - l e v e l and a low-level a c t i v i t y area

Figure 6.3 shows a n e l e v a t i o n view of V'ne r e a c t o r and i n d i c a t e s tile p o s i t i o n of equipment i n tjne v a r i o u s ce1.l.s. Figlire 6.4, a p l a n view of tile r e a c t o r c e l l , shows -the l o c a t i o n of t h e r e a c t o r , puiips, and fuel and b l a n k e t h e a t exchangers. Figure 6.5 i s an e l e v a t i o n of t h e r e a c t o r cell. 'The Hasbelloy N r e a c t o r v e s s e l has a s-j,de w a l l i;hi.ckness of about L-1/4 i n . aiid a head t n i c k n e s s of about 2-1/4 i n . ; it i s designed t o o p e r a t e a t L20O0F and. 1.50 p s i . The plenum chambers, with J-/4,-in.-thick w a l l s , comiiunicate witkin t h e ex-terrial hea-t exchangers by c o n c e n t r i c inle-t-ouLlet p i p i n g . The i n n e r p i p e has s l i p j o i n t s t o accoirvnoclate thermal e.xpansion. By-pass flow through -these s l i p j o i n t s i s about 1% of tine t o t a l flow. A s i n d i c a t e d i n F i g . 6.5, t h e h e a t exchangers a r e suspended from t h e t o p of t h e c e l l aiid. a r e l o c a t e d below t h e r e a c t o r . Each fu.el pwcrp has a f r e e fluid s u r f a c e and a s t o r a g e volume which p e r n i t r a p i d drainage of f u e l f l u i d from t h e core upon l o s s of flow. In a d d i t i o n , %he f u e l salt; can be d r a i n e d t o t h e dump t a n k s when t h e r e a c t o r i.s s h u t dmm for an extended time. The e n t i r e r e a c t o r c e l l is kept 31;high temgera-Lme, while c o l d l l f i i i g e r s l land the-rmal i n s u l a t i o n surround.s t r u c t u r a l suppor-1; members and a11 s p e c i a l equipment which m u s t be kept a t r e l - a t i v e l y low temperat u r e s . The c o n t r o l - r o d d r i v e s a r e l o c a t e d above -the core, and. t h e cont r o l rods a r e i n s e r t e d . i n t o t h e c e n t r a l region of t h e c o r e . ORNL-DWG 66-795

EXCHANGFR

001 ANT S4LT PUhlPS

t I I

p I

BLANKET HEAT EXCHALGER

CONTROL AREA 1

--I

ALL DIMFNSIONS ARE IN FEET ~

F i g . 6.2.

t80

Plan View o f MSBR C e l l Arrangement.

175 0RNL:DUG

,cooi.m r 1

SPLT PUMPS-,

FUEL CIRCULATING

G6-733

CONTROL ROD DRIVE

/RILANKET

CIRC!JLATING PUMP

CONTROL ROOM

ORNL-DWG 66-1787

F i g . 6.4. P l m View of MSBR Reactor C e l l Showing h e a t i o n of Re-

actor E q u i p m e n t .

1-76 FUEL. PUMP MOTOR

OHNI.-DVdG

,CONTROL

ROD DRIVES

/BLANKET

PUMP MOTOR

66-794

I O - f t - d i o r n CORE

--REACTOR

VESSEL

FUEL SAIL1 IDISTRIBUTlON PLENUMS

HEAT REMOVAL -

PRIMPRY HEAT EXCHANGFR

â&#x20AC;&#x2DC;-REACTOR CELL HEATERS

F i g , 6.5.

E l e v a t i o n of Reactor C e l l .

The r e a c t o r v e s s e l , about 14 f t in diameter by about 15 f t high, c o n t a i n s a 1 0 - f t - d i m core assembly composed of r e e n t r y - t y y e g r a p h i t e f u e l c e l l s . The g r a p h i t e tubes a r e a t t a c h e d t o t h e two plenum chambers a t t h e bottoiii of t h e r e a c t o r w i t h grzphite-to-metal tra?.isiti.on. s l e e v e s F u e l from t h e entrance plenum flows up f u e l passages i n the o u t e r region of tine fuel- c e l l and down through a s i n g l e c e n t r a l - passage t o t h e e x i t plenum. The f u e l flows from t h e e x i t plenum t o t h e h e a t exchangers, t h e n t o t h e pump, and back t o t n e r e a c t o r . R 1-1/2-f%-thick mol.ten-salt b l a n k e t plus a l / & f t - t h i c k g r a p h i t e r e f l e c t o r surround t h e c o r e . The b l a n k e t s a l t a l s o permeates t h e i n t e r s - L i c e s of t h e core l a t t i c e s o t h a t f e r t i l e m a t e r i a l flows through t h e c o r e without mixing w i t l n t h e f i s s i l e f u e l s a l t . The MSBR r e q u i r e s s t r u c t u r a l i n t e g r i t y of t h e g r a p h i t e f u e l c e l l . In o r d e r t o reduce t h e e f f e c t of radj.ation damage, t h e f u e l c e l l s have been

1.77 made small t o reduce t h e fast-flux g r a d i e n t a c r o s s t h e g r a p h i t e wall. Also, t h e c e l l s a r e anchored only a t one end t o p e - m i t axial movement. The c o r e volume has been made l a r g e i n order -Lo reduce ti?e f l u x level. i.n t h e c o r e . I n addikion, t h e r e a c t o r i s designed t o pe-miit replacement 0% t h e e n t i r e g r a p h i t e c o r e by remote means i f r e q u i r e d . Figure 6.6 shows a c r o s s s e c t i o n of a f u e l c e l l . F u e l f l u i d f l o w upward through t h e small passages and dowmard through t h e l&rge c e n t r a l passage. The o u t s i d e diameter of a f u e l c e l l t u b e i s 3.5 i n . ; t h e r e a r e 534 of t h e s e t&es spaced on a & . & i n . t r i a n o d a r p i t c h . The tube assemb l i e s a r e surrounded by hexagonal blocks of moderator g r a p h i t e w i t h b l a n k e t s a l t f i l l i n g t h e i n t e r s t i c e s . 'The nominal c o r e corrrposition is 75% g r a p h i t e , l8$ f u e l salt, and 7% b l a n k e t s a l t by volume. A s i m r y of parameter v a l u e s chosen f o r the MSBR design is gri.ven i n Table 6.1.

F u e l Processing Tjne primary o b j e c t i v e s of f u e l p r o c e s s i n g a r e -to p u r i f y and recyc1.e f i s s i l e and c a r r i e r c o q o n e n t s and t o millirni.ze f i s s i l e inventory while holding l o s s e s t o a low v a l u e . The f l u o r i d e volatility-vacuim d i s t i l l a t i o n process f u l f i l l s t h e s e ob jec-Lives through simple o p e r a t i o n s .

The c o r e f u e l i s conveniently processed by- f l u o r i d e v o l a k i l i t y and vacuum d i s t i l l a t i o n . Ulxnket p r o c e s s i n g i s accomplished by f l u o r i d e v o l a t i l i t y alone, and t h e p r o c e s s i n g c y c l e time i s s h o r t enoixh t o maint a i n a v e r y low c o n c e n t r a t i o n of f i s s i l e m a t e r i a l . The e f f l u e n t m6 i s absorbed by f u e l s a l t and reduced t o WL+by t r e a t m e n t w i t h hydxogen t o r e c o n s t i t u t e a f u e l - s a l t rnixture of tize d e s i r e d composition. Molten-salt, r e a c t o r s a r e i n h e r e n t l y s u i t e d t o t h e d e s i g n of processing f a c i l i t i e s i n t e g r a l wie'n t h e r e a c t o r p l a n t ; t h e s e f a c i l i t i e s r e q u i r e only a sirall amoimt of cell space adja,cent Lo -the r e a c t o r cell. Because all servi.ces and equipment a v a i l a b l e t o t h e r e a c t o r are a v a i l a b l e t o t h e p r o c e s s i n g p l a n t and because shipping and s t o r a g e charges a r e eliminated, i n t e g r a l p r o c e s s i n g f a c i l i t i e s permit s i g n i f i c a n t savings i n c a p i t a l . and operatiiig c o s t s . Also, t h e p r o c e s s i n g p l a n t inventory of f i s s i l e m a t e r i a l i s g r e a t l y reduced, r e s u l t i n g i n low f u e l i n v e n t o r y charges and inrproved fuel u t i l i z a t i o n c h a r a c t e r i s t i c s f o r t h e reactor. The p r i n c i p a l . s t e p s i n c o r e and b l a n k e t stream processing of t h e TGBX a r e shown i n F i g . 6.7. A small side stream of each f l u i d i s cont i n u o u s l y withdravn from t h e f u e l and b l a n k e t c i r c u l a t i n g loops and i s c i r c u l a t e d through t h e p r o c e s s i n g system. After processing, t h e decontaminated f l u i d s a r e r e t u r n e d t o t h e r e a c t o r a t some convenient p o i n t f o r example, v i a t h e f u e l and f e r t i l e strecam s t o r a g e tanks.

F u e l inven-t;ories r e t a i n e d i n t h e processing plaiit a r e e s t i m a t e d t o be about 10% of t h e r e a c t o r system i n v e n t o r y f o r c o r e p r o c e s s i n g and l e s s than 1% f o r b l a n k e t processing.

ORNL-DWG 6 6 - 4 7 8 8

-BLANKET

PASSAGE

MODERATOR ( G R A

MODERATOR HOI..D DOWN N U T (GRAPHITE 1

REACTOR

- - - - ' M E T A L TO GR,APHlTE S I ~ I P - J O IN T ----

M E T A L TO G R A P H I T E B R A Z E D J O I N 1

-BRAZED JOINT

FUEL INLET PLENUM

--- F U E L O U T L E T

PLENUM

179

Table 6.1. Parameter Values of MSBR Design _ _ I

Power, Mw â&#x20AC;&#x2DC;Yhe%mal F1.ectrical

2220 1000

0.45

Themal e f fici e m y Plant f a c t o r

0.80

Dimensions, f t Core height Core diameter Blanket tliickne s s Ra,dial kial Reflect o r thickness volumes, f-t3 Core 13iaidcet

12.5 10.0

1.5 2.0 0.25 982 1120

Volume f r a c t i o n s Core

Fuel salt Fertile salt Moderat oT S3l.anke-L Ferti2.e s a l t Sakt volumes, f t 3 Fuel Co m Blanket . Plenums Heat exchanger and piping Processing

Total

Eâ&#x20AC;&#x2122;ertile Core Blanket Heak exchanser and p t p b g Storage (protact,iniwn decay) Processing

Total

0.169 0.0735 0.7575 1.0 166

26 147 345 33

717 72 3.121 100 2066 24 3383

Salt compositions, mole $ Fuel

LiF BeF2 U F ~(fissll-e1 Fertile

LiF BeF 2

TW 2, U F ~(fissile)

63.6 36.2 0.22

?L,O

2.0 27.0 0.0005

181 Ta'ole 6 .I. (continued)

Core a t m i r a t i o s Th/U

41.7

C /u

5 800

Fi s si3-e inventory , kg

769

260

F e r t i l e inventory, thousands o f kil.ograms Processing by f l u o r i d e v o l a t i l i t y

Cyc1.e time, days Rat e, f t /day Unit processing COS^, $ / f t 3

Fuel Stream

14.5

183

Fer%ile Stream 23

14.4. 6.85

Heat Exchange and Steam Systems The s t r u c t u ~ a m l a t e r i a l f o r a11 components contacted by molten s a l t i n t h e f u e l , b l a n k e t , and coolant systems, including t h e r e a c t o r v e s s e l , purirps, h e a t exchangers, and p i p i n g and s t o r a g e tanks, i s IiastelLoy N . The primary heat exchangers a r e of the tube-and-shell t y p e . Each s h e l l c o n t a i n s two concentric tube bimdles connected i n s e r i e s and a%tached t o f i x e d tube s h e e t s . The f u e l s a l t flaws downward i n tine o u t e r s e c t i o n of tubes, e n t e r s a plenum a t t h e bottom of t h e exchanger, and then flows upward t o t h e pump through t h e c e n t e r s e c t i o n of t u b e s . Ent e r i n g 3.t t h e t o p , Yne coolant s a l t f l o w on t h e b a f f l e d shell s i d e of t h e exchanger down t h e c e n t r a l core, uad-er t h e b a r r i e r t h a t s e p a r a t e s t h e two s e c t i o n s , and up t h e o u t e r annular s e c t i o n .

Since a l a r g e telcrperature d i f f e r e n c e exis-Ls i n t h e two tube sect i o n s , t h e tube s h e e t s at t n e bottom of t h e exchanger a r e not a t t a c h e d t o t h e s h e l l . The design permits d i f f e r e n t i a l tube gr&h between t h e two s e c t i o n s without c r e a t i n g troublesome skress problems. To accomp l i s h t h l s , t h e t u b e s h e e t s a r e connec-Led a t t h e bottom of t h e exchanger by a bellows-tyf;e j o i n t . This arrangement, e s s e n t i a l l y a floa-king plenum, peirmits enough r e l a t i v e motion between t h e cenkral and o u t e r tube s h e e t s t o compensate Tor d i f f e r e n t i a l tuke growth without c r e a t i n g i n t o l e r a b l e s t r e s s e s i n t h e j o i n t , t h e tubes, or t h e pump. The blanket h e a t exchangers i n c r e a s e Vne temperature of t h e coobant l e a v i n g t h e primary core heae exchangers. Since t'ne c o o l a n t - s a l t tempera t u r e r i s e through t h e blanket exchangers i s small and t h e flow r a t e i s r e l a t i v e l y high, t h e exchangers a r e designed f o r a s i n g l e s h e l l - s i d e pass f o r t h e coolant s a l t , although two-pass f l a w i s r e t a i n e d for t h e blanket s a l t i n t'ne t u b e s . SLraight tubes SiTith two tiibe s h e e t s are used.

The superheater i s a U-tube U-shell exchanger using disk a,nd donut b a f f l e s w i t h varying spacing. It i s a long, s l e n d e r exchanger having

182 r e l a t i v e l y l a r g e b a f f l e spacing. The b a f f l e spacing is established. by t h e sheJ-1-side p r e s s u r e drop and by t h e tempera-Lue g r a d i e n t a c r m s Yne t u b e w a l l and i s g r e a t e s t i n t h e c e n t r a l p o r t i o n o f the exchanger, where t h e temperature d i f f e r e n c e between t h e f l u i d s i s high The supercri-tical.. f l u i d euters t h e tube sride of t h e superheater a t 700째F an& 3800 p s i and l e a v e s a t 1000'F and 3600 p s i . The r e h e a t e r s t r a n s f e r energy from t h e c o o l a n t s a l t t o tlie working fluid before i t s use i n the i n t e r m e d i a t e - p r e s s w e t u r b i n e . A shell-t,uloe exchanger i s used, producing steam at, l-OOO째F a.nd. 540 p s i .

Since -Yne f r e e z i n g temperature of t h e secondary s a l t c o o l a n t 5.s about 700째F, a high working-fluid i n l e t temperature i s r e q u i r e d Preheaters along w i t h prime f l u i d , a r e used i n rai.si:ng t h e -Lempera;ti.re of t h e worki n g f l u i d e n t e r i n g t h e su&)erheatero. Prime fluid goes t h r o u g h a p r e h e a t e r exchanger and l e a v e s a t a p r e s s u r e of 3550 psi and- a tempera-Lure of about 870'F. It J.s t h e n i n j e c t e d i n t o t h e feedwater i n a mixing t e e , produ.ci.ne; f l u i d a t 700'F and 3500 p s i . The p r e s s u r e i s t h e n i n c r e a s e d to about 3800 p s i by a p r e s s u r i z e r (feedwater pump) before t h e f l u i d . . e n t e r s the superheater. e

C a n i t a l Cost E s . t i n i a t e s Keactor Power P l a n t Preliminary estiiilates O S t h e c a p i t a l c o s t of a 1 0 O O - ~ c J ( e l . . e c t r i c a l )

MSBR power s t a t i o n i n d i c a t e a d i r e c t c o n s t r u c t i o n c o s t of abou-1; $S0,4 m i l l i o n . A f t e r apply-ing t h e i n d i r e c t c o s t factor's used i n t h e ad-vanced

c o n v e r t e r e v a l u a t i o n , an estimated t o t a l p l a n t c o s t of $l.l-3-6 mj.ll-ion i s obtained. A s m a r y o f p l a n t costs i s given i i i Table 6.2. The conc e p t u a l d.esi.gn w a s not, s u f f i c i e n t l y d e t a i l e d t o permit a completely rel i a , b l e e s t i m a t e ; however, t h e design and estirm.f-,eswere s t u d i e d thoroug1il.y enough, t o make meanjxgful cornparisons w i t h previous c o n v e r t e r - r e a c t o r p l a n t c o s t s LuCl.i.es. The r e l - a t i v e l y low c a p i t a l c o s t e s t i r m t e obtained r e s u l - t s from t h e small p h y s i c a l s i z e of t h e MSBII and t h e simple control- r e q u i r e ments. Ti?e r e s u l t s of t h e study e:ncourage t h e b e l i e f Ynat t h e c o s t of a n MSSR power s t a t i o n w i . l l be as l o w as for s t a t i o n s u t i l i z i n g ocher rea c t o r concepbs

The operating and rmintenance costis of t h e MS3R were n o t e s t i i i a t e d . Rased on the ground r u l e s used i n r e f . 1, Ynese c o s t s would be about 0.3 mill/kwhr ( e l e c t r i c a l )

Fuel Recycle P l a n t The capital c o s t s a s s o c i a t e d w i t h f u e l recycl-e equipment were obt a i n e d by itemizing and c o s t i n g t'ne major process equipment reqifired and by estiumti.ng t h e c o s t s o f s i t e , b u i l d i n g s , instrumentation, waste disposal, and. 'bifilding s e r v i c e s a s s o c i a t e d witin fue1. r e c y c l e .

183 Table 6.2. Preliminary Cost-Estimate Summaryaâ&#x20AC;&#x2122; f o r a 1000-MW( ~ l e c - ~ r i c aMSBR ~ . ) Power S t a t i o n F e d e r a l Power Commission Account 20

costs

(thousands of d o l l a r s 1

b Land and land r i g h t s S t r u c t u r e s and improvements 211 Ground improvements 212 3 u i l d i n g s and s t r u c t y e s .1 Reactor b u i l d i n g .2 Turbine b u i l d i n g , a u x i l i a r y b u i l d i n g , and feedwater h e a t e r space .3 O f f i c e s , shops, and l a b o r a t o r i e s .4 Waste d i s p o s a l buil.ding .5 Stack .6 Warehouse .? Miscellaneous S u b t o t a l account 212 T o t a l account 21 Beact o r p l a n t eqwiprnent 221 Reactor equipment .1 Reactor vessel .2 C o n t r o l rods .3 S h i e l d i n g and containment .L+ Heating-cooling systems and vapor suppres s i o n systern .5 Moderator and r e f l e c t o r . 6 ReacLor p l a n t crane S u b t o t a l account 221

222

223

Heat t r a n s f e r systems .l Reactor c o o l a n t system .2 Intermediate cooling system .3 Steam g e n e r a t o r and r e h e a t e r s .4 Coolant supply and t r e a t m e n t d .5 Coolant s a l t i n v e n t o r y S u b t o t a l account 222

Nuclear f u e l handling and s t o r a g e ( d r a i n tariks) 225 Radioactive waste t r e a t m e n t and d i s p o s a l (off-gas system) 226 I n s t r u m e n t a t i o n and c o n t r o l s 227 Feedwater supply and t r e a t m e n t 228 Steam, condensate, and- FW p i p i n g 229 Other r e a c t o r p l a n t equiyment (remote maintenance 1 T o t a l a c c o i u t 22

360

866

4, 181

2 832

1,160 150 76

40 30

8,469

9,335

1,610 250 1,477 1,200 1,089

265

---T-pE 6, â&#x20AC;&#x2DC;132 1 J

9,853 300 354

19,186

1,700 450 4,500

4,051 4,069 5, OOOe

44, 84?

Ta,ble 6.2 (continued) 23

T'urbine-generator units 231. Turbine-generator u n i t s 232 C i r c u l a t i n g water system 233 Condensers and auxiliaries 234 C e n t r a l lube o i l system 235 Turbine p l a n t i n s t r u m e n t a t i o n 236 Turbine p l a n t p i p i n g 237 A u x i l i a r y equiprient f o r g e n e r a t o r 2323 Other t u r b i n e p l a n t equipment T o t a l account 23

24 Accessory e l e c t r i c a l ,241. Switchgear, main and s t a t i o n s e r v i c e 242 Switchboards 243 S t a t i o n s e r v i c e t r a n s f o r m e r s 244 A i x i l i a r y g e n e r a t o r ,245 D i s t r i b u t e d items T o t a l account; 2h

Miscellaneous

T o t a l d i r e c t , c o n s t r u c t i o n cost,g Total indirect costs

ToLal p l a n t c o s t

19,174 I., 243 1,690

25 22Of 66 25 22,523

550 128 169 50 2,000

2,897 800

80,402

33,181

113,5 83

%stirnates are based on 1966 c o s t s , assuming an established- moltens a l t ~iucl.earpower p l a n t i n d u s t r y

b h n d c o s t s a r e not; included i n t o t a l . d i r e c t c o n s t r u c t i o n c o s t s C

MSRR containment c o s t i s incl.iided. i n account 2.21."3.

dAsswned as $300,000 on t h e b a s i s o f M Sm experience. e The a t q l e NSBR al.1.awance f o r remote maintenance may be t o o high, and some of tlie included replacement equipment allowances could more 1ogical.l.y be e l a s s l f i e d as operating expenses r a t h e r t h a n f ; i . r s t c a p i t a l c o s t s . fBased on Bull R m p l a n t c o s t o f $160,000 p l u s -37% f o r u n c e r t a i n t i e s .

gDoes n o t include account 20, la.nd c o s t s . d i r e c t cos-Ls

T z i s i s included i n t h e i n -

Table 6.3 summarizes .the d i r e c t c o n s t r u c t i o n c o s t s , t h e i n d i r e c t c o s t s , and t o t a l c o s t s a s s o c i a t e d w i - t i l t h e i n t e g r a k d - processi-ng f a c i l i t y having approximate1.y Yhe r e q u i r e d c a p a c i t y . The o p e r a t i n g and maillieilance c o s t s f o r t h e fuel recycle f a c i l i t y include l a b o r , l a b o r overhead, chemicals u t i l l - t i . e s , and maintenance r m t e r i a l s . The t o t a l annual c o s t for the c a p a c i t y considered h e r e (15 f i 3 o f fuel. s a l t p e r day and 105 tt' of f e r t i l e s a l t p e r day) i s e s t i mated t o be $721,230, which i s equivalezi-b t o about 0.1 inil-l/kwhr ( e l m t r i c a l ) .2 A breakdown of t h e s e charges i s given i n Table 6 . 4 .

185 'Table 6.3. -

~-~ ~

Sumrnary of P r o c e s s i n 1000-Mw ( E l e c t r i c a l

Processing-Plant r n e n d i t u r e s

costs

I n s t a l l e d process equipment

$ 853,760

S t r i i c t u r e s and improvements

556,770

Waste s t o r a g e

387, 970

Process p i p i n g

1.55,800

Proc es s i n st r m e n t a t ion

272,100

E l e c t r i c a l nuxil.iaries

84,300

Sampling connect ions

20,000 128,060

S e r v i c e and u t i l i t y p i p i n g

50,510

Insulation

100,000

Radiation monitoring Total d i r e c t costs

$2,609,270

Construction overhead (30% of d i r e c t c o s t s )

782,780

T o t a l c o n s t r u c t i o n cost

3,392,050

Subtotal p l a n t c o s t

4,240,050

Engineering and i n s p e c t i o n (25% of t o t a l construction cost 1

1,060)020

C o n t i q e n c y (25% of s u b t o t a l p l a n t c o s t ) Total p l m t cost

$5,300,080

Summary of Operating aiid Maintenance Charges for Fuel Recycle i n a 1000-MET ( E l e c t r i c a l ) MSBE

Table 6.4.

Operation and Maintenance Expenditures Direct labor

Iabor overhead

Annual Charges $222,000 177,600

Chemicals

14,640

Waste c o n t a i n e r s

28,270

U t i l i t ie s

80, 300

Maintenance r m t e r i a l s Site S e r v i c e s and u t i l i t i e s Proc ess equipmen-t

'Total annual chazges

2,500 35,880 160,040 $721,230

186 Nuclear Performance and F u e l Cycle Analyses The f u e l c y c l e c o s t and t h e f u e l y i e l d a r e c l o s e l y r e l a t e d , y e t independent i n t h e sense t h a t two n u c l e a r designs can have similar c o s t s b u t s i g n i f i c a . n t l y d i f f e r e n t y i e l d s . The ob j e c t i v e of t h e n u c l e a r design c a l c u l a t i o n s w a s p r i m a r i l y t o f i n d t h e c o n d i t i o n s tlnat gave t h e I-owest f u e l c y c l e c o s t , and then, without a p p r e c i a b l y i n c r e a s i n g t h i s c o s t l t h e h i g h e s t fuel. y i e l d . Analysis Procedures Cal.cu.lation Method. The c a l c u l a t i o n s were p e r f oriiied w i t h OP'TLMERC a combinahion of an o p t i m i z a t i o n code w i t h t-h e JYiERC m d t i g r o u p , d i f f u s i o n , e q u i l i b r i u m r e a c t o r code. The program MERC' c a l c u l a t e s t h e n u c l e a r p e r formance, t h e e q u i l i b r i u m c o n c e n t r a t i o n s of t h e v a r i o u s n u c l i d e s , i n c l u d i n g f i s s i o n products, and t h e f u e l c y c l e c o s t for a given s e t of cond i t i o n s . O P T m l C permits up t o 20 r e a c t o r parameters t o be v a r i e d , witlnin l i m i t s , i n order t o dete,mniae a n optimim, by t h e method of s t e e p e s t a s c e n t . 'The designs were optimized e s s e n t i a l l y f o r rninimwn f u e l c y c l e c o s t , w i t h Lesser weight given t o maximizing t h e a n n u a l fuel. y i e l d . Typical. parame t e r s v a r i e d were t h e r e a c t o r dimensions, b l a n k e t t h i c k n e s s , f r a c t i o n s of fuel.. and f e r t i l e s a l t s iu t h e core, and f u e l and f e r t i l e stream proce s s i n g r a t e s .. Several. equations were included i n the c0d.e for approxhnating c e r -Lain c a p i t a l arid o p e r a t i n g c o s t s 'chat v a r y w i t h t h e design parameters (e.g,, c a p i t a l c o s t of t h e r e a c t o r v e s s e l , which v a r i e s w i t h t h e r e a c t o r dimensions). These c o s t s were autorflat:i.calS_y added t o t h e f u e l c y c l e c o s t i n t h e o p t i m i z a t i o n r o u t i n e s o that; t h e o p t i m i z a t i o n s e a r c h would tak.e i n t o account a l l known economic f a c t o r s . However, only t h e f u e l c y c l e cost i t s e l f i s reported i n the r e s u l t s . Modified G&V-1-4CKERMOS c r o s s - s e c t i o n libra:c.i.es were used t o compute t h e broad group cross s e c t i o n s f o r t h e s e c a l c u l a t i o n s . It w a s assumed %ha%a1.l n u c l i d e s i n t h e r e a c t o r sys.t;em are a t t n e i r e q u i l i b r i u m conc e n t r a t i o n s . To check tinis asswflption, a t y p i c a l r e a c t o r design w a s examined t o d e t e r n i n e 4Aie operating time r e q u i r e d for t h e v z r i o u s uranium i s o t o p e s t o approach t h e i r eq1uil.ibriu.m c o n c e n t r a t i o n s from a s t a r t u p w i t h 235U. It was found t h a t 233U and. 235U were w i t h i n '35% of t h e i r e q u i l i b r i u m c o n c e n t r a t i o n s i n less t h a n two y e a r s . Uranium-234 w a s w i t h i n 95$ of equilibrium a f t e r e i g h t years, while 236U wads witnl:n 80% a f t e r ten. y e a r s . Since t h r breeding performance depends mainly on Lht! r a t i o of 233U t o 235U i n t h e f u e l , t h e e q u i l i b r i u m c a l c u l a t i o n appears t o be a good repr e s e n t a t i o n of t h e l i f e t i m e performance of t h e s e r e a c t o r s , even f o r startup on 2 3 5 ~ . Basic Assumptions Economic. T'ne b a s i c economic a s s u p t i o m employed in t h e c a l c u l a t i o n s are giv/kn i n Table 6.5. The v a l u e s of t h e f i s s i l e i s o t a p e s were taken from Lhe cui-reni AEC T r i c e schedule.

187 The p r o c e s s i n g c o s t s a r e based on t h o s e given i n t h e s e c t i o n e n t i t l e d " C a p i t a l Cost Estimates" and a r e included i n t h e f u e l cyc1.e c o s t s . The c a p i t a l and. o p e r a t i n g c o s t s were e s t i m a t e d s e p a r a t e l y f o r each stream as a f u n c t i o n of p l a n t throughput, based on t h e volume of s a l t processed. The t o t a l p r o c e s s i n g c o s t i s assumed t o be a f u n c t i o n of t h e througlip~rt t o some f r a c t i o n a l . power c a l l e d Yne s c a l e f a c t o r . P r o c e s s i n g . The p r o c e s s i n g scheme i s t'nat i n d i c a t e d i n F i g . 6.7. A f i s s i l e rmteria.1 l o s s of O . l $ p e r pass through p r o c e s s i n g w a s assumed.

I n a d d i t i o n t o t h e b a s i c p r o c e s s i n g scheme employed, results were a l s o obta,ined f o r t h e case where p r o t a c t i n i u m can be removed d i r e c t l y from t h e bla.&et stream. The improvement i n performance under t i i e s e circumstances i s 8 measure of t h e incenti.ve t o develop p r o t a c t i n i u m r e moval a b i l i t y . F i s s i o n Procluct Behavior. The d i s p o s i t i o n of t h e v a r i o u s f i s s i o n products was assuiied as shown i n Table 6 . 6 . The behavior of 135Xe and o t h e r f i s s i o n gases has a s i g n i f i c a n t i n f l u e n c e on n u c l e a r performance. A gas s t r i p p i n g system i s provided t o remove t h e s e gases from t h e f u e l s a l t . However, p a r t of t h e xenon could d i f f u s e i n t o t h e moderator graphi t e . I n t h e c a l c u l a t i o n s r e p o r t e d h e r e , an 135Xe poison f r a c t i o n of 0.005 was assumed. Corrosion Product Behavior The c o n t r o l of c o r r o s i o n products i n m o l t e n - s a l t f u e l s does not appear t o be a s i g n i f i c a n t problem, and t h e e f f e c t of c o r r o s i o n products w a s n e g l e c t e d i n t h e n u c l e a r c a l c u l a t i o n s . The p r o c e s s i n g method considered h e r e can control. corrosi-on product buildup i n t h e f u e l .

Table 6,5.

Basic Economic Assumptions

Reactor power, Mw ( e l e c t r i c a l ) Thernial e f f i c i e n c y ,

1000

Load f a c t o r

0.80

Cost assumpt ions Value of 233U and 233Pa, $/g ~ a l - u eof 2 3 5 ~ , $/g Value of thorium, $/kg Value of c a r r i e r s a l t , $/kg C a p i t a l charge, annual ra%e, f~ Plant Nondepreciating c a p i t a l , i n cluding f i s s i l e inventory Processing c o s t , d o l l a r s p e r cubic f o o t of s a l t F u e l (at 1 0 ft3/da ) B l a i k e t (a.t 100 f t / h y l Processing c o s t s c a l e f a c t o r (exponent 1

12 12 26 12 10

228

8.47

0.4

Table 6 . 6 .

D i s p o s i t i o n of F i s s i o n Products i n MSBX & a c t o r and Processing S y s k m

___-.-_

Elements p r e s e n t as gases; assmid t o be p a r t l y absor’oed by g r a p h i t e and p a . z i l y removed by gas s t r i p p i n g (1/2$ poisoning assumed)

K r , Xe

Elements which p l a t e out on m e t a l s u r f a c e s ; assmiled t o be removed instantaneoiisly

Ru, iih, Fd, Ag, I n

Elements which f 01x1 v o l a t i l e f l u o s i d e s ; assumed t o be removed. i n t h e f l u o r i d e v o l a t i l i t y process

Se, B r , Nb, Mo, Tc, Y e , I:

Elemen-ts which form s t a b l e fluorides l e s s v o l a t i l e t h a n LiF; assumed t o be s e p a r a t e d by vacuum d i s t i l l a t i o n

Sr, Y, Ba, La, Ce,

Elements which a r e n o t s e p a r a t e d from t h e c a r r i e r s a l t ; assumed t o be removed oriiy by s a l t discard

Rb, C d ,

‘Table 5.7.

Er, Nd, Fm, sm, Eu, G d , Tb &I,

MSBK P e r f o m n e e

Fu.el y i e l d , $/year

4.86

Breeding r a t i o

1.049

F i s s i l e l o s s e s i n processing, atoms/fissi.l.e ab s o r p t i oi?

0.0057

NeuLron production p e r f i s s i l e a b s o q t i o n ,

2.221

S p e c i f i c i n v g n h s y , kilograms of f i s s i l e m a t e r i a l p e r MW ( e l e c t r i c a l )

0.769

S p e c i f i c power, Nw (thermal) p e r kilogram of f i s s i l e m a t e r i a l

2.89

Power d e n s i t y , core average, kw/l.i.ter Gross I n fuel. s a l t

473

YTeutron flux, c o r e average em-* see-’ Thermal Fast F a s t , over 100 kev

12.1 3.1

, 10’”

neutrons

6.7

Thermal f l u x f a c t o r s , c o r e , pe.zk/iuean Radial Axial

2.22 1.37

F r a c t i o n of f i s s i o n s i n f u e l stream

0.987

F r a c t i o n o f f i s s t o n s i n thermal neutron groirp

0.806

M a n q of 233U

2.221

Mean q of 2 3 5 ~

1.958

CS,

189 Nuclear Design Analysis The important pammeterc d e s c r i b i n g t h e IGBR design a r e given i n Table 6.1. Many of t h e parameters were b a s i c a l l y fixed by t h e groimd r u l e s f o r the e v a l u a t i o n o r by %he engineering design. These i n c l u d e tile -f;lne-mlal e f f i c i e n c y , pLant f a c t o r , c a p i t a l charge r a t e , maxinium f u e l v e l o c i t y , s i z e of f u e l t u b e s , p r o c e s s i n g c o s t s and fissile l o s s rxLe > a,rd tile out-of-core f u e l inventory. The parameters which were optimized by O P T I m C were t h e r e a c t o r dimensions, t h e power density-, t h e core composition, i n c l u d i n g %he C/U and Th/U r a t i o s , and t h e p r o c e s s i n g rates. Nuclear Performuice. The r e s u l t s of t h e c a l c u l a t i o n s f o r t h e NSBR design are given i n Table 6.7, and t h e neutron balance i s given i n Table 6*8. The b a s i c design has .the i n h e r e n t advantage of no neutron losses Table 6.8.

MSBR Neutron Balance Neutrons p e r F i s s i l e Absorption

Material

Absorbed Total.

Absorb e d by F i s s i o n

Produced

0.9710

0.0025

0.005cS

0.9ll.9

0.8090 0.0004

2.0233 0.001.0

0.0079

0.0936 0.0881

0.0115

0,0014

0.070EZ 0.0001

0.1721 0.OOOL

0.0009

0.0185

0.0623 0.0030 0.0300

0.0050 0.0069

Other f i s s i o n products Delayed neutrons l o s t " '0

0.0196

0.0050 0.0012

Leakage

Total.

%clayed

0,001.8

2.2209

neuLrons e m i t t e d o u t s i d e the core.

0.8828

bLeakage, i n c l u d i n g neutrons absorbed i n t h e r e f l e c t o r .

2.2209

190 t o s t r u c t u r a l -materj.als o t h e r t h a n %he ,moderatoy. Except for some unavoidable Loss of delayed neutrons i n t h e e x t e r n a l f u e l c i r c u i t , t h e r e i s almost zero neutron leakage froin t h e r e a c t o r because of t h e t h i c k b l a n k e t . The neu-tron l o s s e s t o f i s s i o n products are minimized 'by t h e a v a i l - a b i l i t y of rapid. and inexpensive i n t e g r a t e d processj.ng. F u e l Cycle Cost. The components of t h e f u e l c y c l e cos% for t h e MBH a r e given i n Table 6.9. The main components a r e the fLssi1.e inventory and processing c o s t s . The inventor')- c o s t s a r e rather r i g i d f o r a given r e a c t o r design, sirice t h e y a r e 1-argely deterrnrined by t h e assumed e x t e r n a l fuel volume. The p r o c e s s i n g c o s t s a r e , of course, a function of t h e processing cycl..~:times, one o f t h e c h i e f parameters optindzzd. i n t h i s study. MSSR Performance wi'cln P r o t a c t i n i i m Removal Scheme. The a b i l i t y -Lo remave p r o t a c t i n i u m d i r e c t l y from t h e b l a n k e t of t2n.e MSBR has a, marked elrfect on fuel y i e l d and f u e l c y c l e c o s t . Th:is i s due p r i r m r i l y t o t h e marked.. decrease i n p r o t a c t i n i u m neutron absorpkions when p r o t a c t i n i u m i s removed from t h e b l a n k e t region. A simple and inexpensrive scheme f o r t h e removal of p r o t a c t i n i u m from t h e blanket would g i v e the NSBR tine p e r f o r mance i n d i c a t e d under MSBR (Pa) i n Table 6.10; for comparison, t h e resu.l.ts without p r o t a c t i n i u m removal are a l s o given i n t h e t a b l e . _ I . -

Table 6.9. Fuel Cycle Cost f o r YEBR

Fuel Strecam

Fertile

Stream

Total

0.1-180 0.0000 0.0146

0.0324 0.0459 0.0580

0 1504 0.04.59 0.0726

Grand Total

Inventory Fissile" Fertile Salt

0.2690

Total Heplacement Fertile Salt Processing

Total

0.0000 0.0565

0.0185 0.0217

0.! 01.85

0 1.1.02

0 .0441.1.

0.1-513

To-iial

0.0967 0.1513

0 0718

Production c r e d i t

0.4452

Net f u e l c y c l e c o s t

a. Including 233Pa, 233U,

0.0782

and

235U.

191

Power Cost and F u e l U t i l i z a t i o n C h a r a c t e r i s t i c s Based on t h e above, t h e power c o s t , s p e c i f i c f i s s i l e inventory, and f u e l doubling time for t h e MSBR and MSBR (Pa) are summarized i n T a b l e 6.11.

Table 6.11 i l l u s t r a t e s t h e econoaic advantage of MSHR's a s nuclear power p l a n t s A l s o , t h e f u e l u t i l i z a t i o n c h a r a c t e r i s t i c s as measured by t h e product 03 t h e s p e c i f i c i n v e n t o r y and t h e square of the doubling time4 are excell-ent. On - t h i s basis t h e MSBR i s compa.rab1e t o a f a s t b r e e d e r w i t h a s p e c i f i c i n v e n t o r y of 3 kg/m ( e l e c t r i c a l ) a.nd a doubling time of 10.5 years, while t h e MSBR (Pa) i s comparable t o t h e s a m e f a s t breeder w i t h a dou.bling time of 6 y e a r s . I

Table 6.10.

Comparison of MSBR Performance With and Without Protactinium Removal

MSBR, Without Protactinium

Process

Fuel yield, $/year

MSER (Pa),

w i ' c h Protactinium Removal

4.86 1.049

1...071

0.45

0.33

S p e c i f i c inventory, kg/Mw (e1ectrical)

0.769

0.681

S p e c i f i c power,

2.89

3.26

Breedhg r a t i o F u e l cycle c o s t , m i l l s / W n r

Pti

(therrnal)/kg

7.35

2.221

2.22'7

V o l m e f r a c t i o n s , core E'ue 1 Fertile Moderator

0.1-69 0.0745 0.7565

0.169 0.0735

Sa1.t; volumes, f t 3 Fuel. Core Ext-ernal

166

164 551

Neutron production p e r f i s s i l e a b s o r p t i o n , qs

Total

Fertile Total Core a-torn r a t i o s Th/u

c/u

547 -

0.7575

I _

713

717

3383

1317

39 .?

41.?

544-0

5800

192

Power Cost and Fuel. U t i l i z a t i o n C h a r a c t e r i s t i c s of the MSBR am3 t h e MSBR (Pa)

Table 6.11.

C a p i t a l cost

Operating and m t n t e n a n c e cos .Lb CI C

F u e l c y c l e cost

a plant.

1.” 95

1.95

0.30

0-30

0.45

0.33

12% f i x e d charge reate, 80% load f a c t o r , 1000-fib ( e l e c t r i c a l . )

bNomrinal value used i n advanced- c o n v e r k r e v a l u a t i o n (see r e f . 1). C.

value.

Costs of o n - s i t e i n k g r a t e d processing p l a n t a r e included j.n t h i s

References

__-__._ Evaluation of Advanced Con1. M. W Rosenthal et a l . , A Comparative 1965 . v e r t e r s , O R N L - 3 6 Z -&nuary

C . D. S c o t t and W . L. Carter, Prel-iminary Desigri Study of a Cont i n u o u s Fluorination-Vacuum D i s t i l l a t i o n $%teem f o r Regenerating Fuel and F e r t i l e S t r e a m i n a Molten S a l t Breed-er lieactor, ORNL3’791 (January 1966).

T. w. K e r l i n , J r . , h p r . 22, 1964,).

et; &.,

The 14ERC-1 E q u i l i b r i m Code, ORNL-TM-84’7

P . 13. Kasten, “Nuclear Fuel U t i l i z a t i o n and Zconomic Incentives,’’ Paper presented a t t h e Aiierican Nilclear Society Meeting, Nov. 15-18, 1965, Washington, D .C

193

MOETEN- SALT XEACTOR FRGCESSING STUDIES

A close-coupled f a c i l i t y f o r processing t h e fuel.. and f e r t i l e streams of a molten-salt breeder r e a c t o r (M,SRR) w i l l be an i n t e g r a l part; of t h e r e a c t o r system. S t u d i e s a r e i n progress f o r o b t a i n i n g data r e l e v a n t t o -the engineering design of such a processing f a c i l i t y . The processing p l a n t will operate on a s i d e stream withdrawn from t h e rue1 stream, which c i r c u l a t e s through t h e r e a c t o r core and t h e primary h e a t exchanger. For a 1000-Mw ( e l e c t r i c a l ) MSBR, approximately 14.1 f t ' of s a l t per day will. be processed, which wil-1- r e s u l t i n a f u e l - s a l t cycle time of approximately 40 days

The probable method f o r fuel-stream and f e r t i l e - s t r e a m processing i s shown i n F i g . 7.1. The s a l t will f i r s t be contacted with F2 f o r r e moval of uranium as v o l a t i l e UF6. F u r i f i e d m6 w i l l . be o'utained from t h e f l u o r i n a t o r off-gas ( c o n s i s t i n g of 1 p 6 , excess ~ 2 , and v o l a t i l e f i s s i o n product f l u o r i d e s ) by use o f N a F sorpt-ion. A semicontinuous vacum d i s t i l l a t i o n will t h e n be c a r r i e d out on t h e remaining s a l t f o r t h e r e moval of t h e r a r e e a r t h s , barium, stron.tium, and y t t r i u m . These fisc *.ion products w i l l be removed from t h e s t i l l i n a s a l t volume equivalent t o 0.5% of t h e stream. A s m a l l . f r a c t i o n of s a l t may a l s o have t o be d i s carded a t some s t a g e i n t h e process Tor removal of f i s s i o n produc-tis su.ch OHNL-UWG 65-1801RPA

F2 RECYCLE

[.-F2

RECYCLE

I FZ

WASTE FERTILE SALT 0.46ftyduy

LiF-BeC2- UF,.

W A S T E ~ O Ofi3/doy ~ ~

'LI-078 kg/doy F P's ~

- __

Fig. 7.1. MSf31I Fuel and F e r t i l e Stream Processing.

___

194 1

as zirrconiim, rubidium, and cesium. The b a r r e n s a l t , t h e p u r i f i e d uF69 and the makeup sa1.t w i l l t h e n be recorilbined. This s t e p invol-ves r e duction of UF6 t o UT4, n i x i n g of t h e s e streams, and sparging t h e r e s u l t ant; m a t e r i a l with an H2-HF stream. F i n a l l y , t h e s a l t mixture w i l l be f i l t e r e d before return t o the reactor. Semic ont imious D i s t i l l a t ion The present concept of t h e d i s t i l l a t i o n s t e p i n t h e E B R processi-ng p l a n t w i l l use a continuous feed stream and vapor removal; however, t h e r e wj.1.1 be a buildup of: l e s s v o l a t i l e f i s s i o n prod-ucts (FP) i n a statix pool of l i q u i d i n t h e s t i l l , with period-ic discard.' Fission products W i l l he allowed to b u i l d up i n t h e s.Li1.1. l i q u i d u n t i l t h e heat generation r a t e becomes excessive, o r u n t i l . t h e l i q u i d FP concentration becomes t o o l a r g e f o r u s e f u l decontamination. One measure of t h e decontamination achieved i n t h e d i s t i l l a t i o n process i s t h e r e l a t i v e v o l a t i l i t y of t h e n o n v o l a t i l e f i s s i o n products as compared w i - t h t h e c a r r i e r s a l t . The r e l a t i v e volati.li-t;y o f a nonv o l a t i l e component R compared w i - t i l a more v o l a t i l e component B i n a m i x t u r e of A and B i s defined as

where = r e l a t i v e volati1.ity of A compared with B, Ai3 y = vapor-phase mole f r a c t i o n ,

x = liquid-phase mole f r a c b i o n . To achieve good decontaiiij.nation from t h e l e s s vol.atile E'P, t h e r e l a t i v e v o l a t i l i t y must be suia,ll. For systems i n which t h e FP concentration i s siizall, t h e r e l a t i v e v o l a t i l i t y can be approximated by

which i s t h e Henry's law constant, HA, used i n t h e expression yA=Hx

A A

Tflus, determination of t h e Henry's law c o n s k n t o r re1.ative v o l a t i l i t y f o r each of t h e nonvolatil-e FP w i l l be s u f f i c i e n t for determining t h e s i z e and o p e r a t i n g conditions f o r t h e d i s t i l . l a t i a n s t e p . The Importa.rrce of r e l a t i v e v o l a t i l i t y i n determininp; t h e operating c h a r a c t e r i s t i c s o f a distil.l.ation system is shown by t h e foI.lowing calcul a t i o n . Consider a m a t e r i a l balance of an E'P i n t h e proposed d i s t i l l a t i o n

1.95

process. The amount of FP f e d i n t o t h e s t i l l . per u n i t Lime (E’xo) must e q u a l t h e FP l e a v i n g t h e s t i l l p e r unit, time ( D J ) , plus t h e r a t e of change of FP i n t h e s t i l l liqLiid d(Vx)/dt:

where

= mole f r a c t i o n OS

FP i n l i q u i d ,

i n l e t mole f r a c t i o n of PP,

mass feed r a t e i n moles/unit time,

D = v a p o r i z a t i o n rate i n moles/unit time,

V = mass o f l i q u i d holdup i n moles,

mole f r a c t i o n of E’P

iii

time.

vapor,

I n t h e above material balance, vapor holdup i s assunied t o be n e g l i g i b l e coi-;lparcd with t h e l i q u i d holdup.

ment

S u b s t i t u t i n g Eq.

So:Lution of Eq.

( 3 ) i n t o t h e m a t e r i a l balance gives, after rearrange-

( 5 ) with t h e boundary c o n d i t i o n

and t h e c o n d i t i o n t h a t t h e l i q u i d holdup V i s c o n s t a n t y i e l d s x = -XO( 1 - 2

-Fat/V

F i n a l l y , t h e average vapor c o n c e n t r a t i o n a t time t i s given by t h e rel a t ion

Figure 7.2 shows t h e e f f e c t OS r e l a t i v e v o l a t i l i t y on t h e F r a c t i o n of FP r e t a i n e d i n t h e l i q u i d f o r d i f f e r e n t v a l u e s of a as a f u n c t i o n of time €or a f e e d r a t e of l L + . l f t 3 of s a l t p e r day and a l i q u i d vo7.ume of 4 f t 3 e For r e t e n t i o n of 90% of the VP introduced t o t h e system during 60 days of continuous d i s t i l l a t i o n , a r e l a t i v e v o l a t i l i t y of -0.001 i s needed.

In order t o e s t a b l i s h t h e r e l a t i v e v o l a t i I - i t y of an FP i n the MSBR c a r r i e r s a l t , it i s necessary t o determine t h e c o n c e n t r a t i o n O P the FP i n t h e vapor a t cquili’orium w i t h a known l i q u i d composition. A t t h i s

196 phase of development, exact o p e r a t i n g c o n d i t i o n s in t h e s t i l l have not been s e t , but t h e followi.j1g ranges appear reasonable: temperature, 900lloo°C; maximum FP Iliquid concentration, 0.1-1.0 mole $; pressure, vapor pressurc of mixture. Since the PERR c a r r i e r s a l t i s a mixture of LiF and BeE’2, t h e exact composition of ’LIE c a r r i e r s a l t or s o l v e n t i n the s t i l l l i q u i d wi1-1 be dependent on o p e r a t i n g tenzpera’cure and pressu-e; however, i n t h e temperat,iire range of i n L e r e s t , t h e major p o r t i o n of t h e s t i l l c a r r i e r s a l t w - l i l l be t h e less v o l a t i l e TSF. ‘Therefore, all. experimental t e s t s were made with bina-ry mixtures of L7-F and FP fl.iioride. I n l a t e r t e s t s rnulticoi11ponent systems w i l l be used.

ORNL-DWG 6 6 - 6 4 A

TIME ( d a y s )

F i g . 7.2. F r a c t i o n of F i s s i o n Product Retained and t h e St,i!L k’unction of Time f o r Several Values of Kelative Volatility.

as a

197 The FP contaminants of m a i n concern are t h e rare e a r t h s . Of t h e s e , t h e ones which w i l l be p r e s e n t i n t h e l a r g e a t miount o r which w i l l present t h e l a r g e s t neutron lo:;ses are Nd, Sm, yrr?, Pr, Eu, La, and C e . These f i s s i o n products w i l l probabljj be p r e s e n t as t h e t r i f l u o r l . d e , with t h e ex-ception of cerium, which might be present p a r t i a l l y as t h e t e t r a v a l e n t fluoride

The equipment used f o r determining rei-ative v o l a t i Z i t i e s w a s a simple equilibrium s t i l l w i t h a cold. f i n g e r i n t'ne vapor phase. This s t i l l w a s c o n s t r u c t e d from 1 - i n . n i c k e l t u b i n g f o r t h e l i q u i d and dj-sengagement space, and 5/8-in. tiubing f o r tile vapor space through which a 3/8-in. nickel. c o l d f i n g e r was i n s e r t e d (Fig. ' 7 . 3 ) . The top of t h e vapor s e c t i o n was connected -Lo vacuwn and i n e r t gas. '1'4ie e n t i r e assembly w a s placed i n a 5-in.-dia;rri tube furnace. Thermocouples were i n s e r t e d i u t h e s t i l l through tliermovells i n t h e l i q u i d phase and a t t h r e e p o i n t s i n t h e vapor phase. During a t e s t , t h e temperature measured a t t h e t h r e e lower p o i n t s was niaintained w i t h i n 5째C of a predetermined value. The c o l d f i n g e r could be cooled by a i r , water, o r a combination of This was d.one by i n t r o d u c i n g t h e coolant through a c e n t e r 1/8-in.d i m tube and removing it -l;hrough t h e annular space between t h e 1/8- and 3/8-in.-dia~fl t u b e s . Gy- u s i n g a coolant sake o f 0.2 s t d l i t e r of H 2 0 p e r minute and 11.4 s t c l l i t e r s of n i r per rninute, t h e -Lip of t h e cold f i n g e r could. be cooled from t h e maximum s t i l l temperature (1075OC) t o l e o s than the melting point of L;iF (847째C) w i t h i n 2 s e c . This r a p i d cooliiig would prevent p r e f e r e n t i a l condensation of t h e l e s s vo1ati.l.e cornponent during

both.

t h e cold-finger operation.

The experimental procedure used was t o f i r s t charge t h e :;.till with a known mixlare of LiF-FP f l u o r i d e ; then, a f t e l - t h e : s t i l l was f i l l e d w i t h an i n e r t gas ( p u r i f i e d heliurn o r argon), it was brought t o tine d e s i r e d tentperature. A t t h i s p o i n t t,he s t i l l w a s s u b j e c t e d to a vacuum p m p with t h e c a p a b i l i t y of reducing t h e p r e s s u r e s t o less t h a n 50 Hg. A f t e r the temperature and. p r e s s u r e reached an apparent steady s t a t e , t h e c o l d f i n g e r was cooled f o r 2 t o 4 t n i n f o r c o l l e c t i o n of a vapor sample. The i n e r t gas w a s again introduced, t h e c o l d f i n g e r was removed arid replaced with a, c l e a n one, and. t h e procedure was repeated.

Tne s o l i d accumulated on t h e c o l d f i n g e r was scraped. o f f , and i t c o n s t i t u t e d t h e equi_libriwn vapor-phase sample. Approximately 0.01 g was c o l l e c t e d f o r each ~ ~ m p l eand , two sanrples were c o l l e c t e d a t each s e t of cond.itions. For each s t i l l l i q u i d mixture, t e s t s were made a t foux tempevaixres, 925, 975, 1025, and 1075'C. Experirflental t e s t s have been made on a l l t h e important r a r e - e a r t h f l u o r i d e s with t h e exception of promethium. R e s u l t s a r e given i n Table 7.1. They are g e n e r a l l y c o n s i s t e n t and compare favorably with results obtained by Kelly2 i n work described i n t h e s u b s e c t i o n "EvaporativeD i s - t i l l a t i o n S t u d i e s on Molten-Salt Fuel Components" of t h i s r e p o r t .

O R N L - D W G 6 5 - 7847 R A

-I-i;iO

-'+j--gsaIH20

AND AIR IN

A N D 4 l R OUT

COMPRESSION FITTING DR I L L E D TH H 0 U G H VACUUM AND INERT

G4S

199 Table 7.1.

E a re E a r t h Fluoride

R e l a t i v e V o l a t i l i t i e s of Bare-Earth Fluorides i n Lcithium Fluoride Liquid Mole Fraction

Average R e l a t i v e Vo La-Lilit i e s

1050' C

950째C

0.0067

0.W3

0.167

0.01

0-033

0.009

0.01

0.025

0.016

0.001

1000O c

900째C

0.. 001 0 .Ol 0.001 0.01

0.038

0.041

0.037

0.043

0.033

0.035

0.024

0.051

0.027

0* 208

0.020 0.028

0.014 0.012

0.018

0.011

0.008

F u e l Recons t i t u t i o n

A necessary s t e p i n . t h e processing 03 t h e MSUR f u e l is the reconibin a t i o n of t h e p u r i f i e d uranium hexafluoride with t h e p u r i f i e d c a r r i e r s a l t , which includes reduction of m6, t h e p r O d L i c t of t h e f l u o r i n a t i o n s t e p , t o W4. The usual method f o r reducing U F C ~t o U2'4 uses e x c e ~ ~ hydrogen i n an H2-F2 flame which produces hydrogen f l u o r i d e as a byproduct. The r e s u l t i n g UF4 powder i s c o l l e c t e d a t t h e base of a t a l l r e a c t i o n v e s s e l . Although t h i s o p e r a t i o n has been reduced t o r o u t i n e p r o duct ion, i t appears unde si r a b l e f o r radiocherni c a l app1i.ca t ion because of t h e i n h e r e n t s o l i d s handling problem. An a l t e r n a t i v e i s t h e reduction o f UFG t o U F L i n a molten salt;, involving only gases and liquids. When U F 6 i s contacted w i t h a molten f l u o r i d e s a l t containing UF4, it i s absorbed Wi%h r e a c t i o n t o form intermediate f l u o r i d e s of uranium such as TJT5. These i n t e r m e d i a t e f l u o r i d e s can then be reduced t o UT4 by c o n t a c t i n g t h e s a l t w i - L h hydrogen. I n i t i a l b u t d e f i n i t i v e t e s t s have shown t h i s a l t e r n a t i v e t o be q u i t e f e a s i b l e . A tower which might serve well t o cond.uet t h i s sec~uenceo f reac-Lions i s shown i n Fig. 7.4. Questions of f r a s i h i l i t y a r e r a i s e d concerning t h e equilibrium d i s t r i b u t i o n 03 the various s p e c i e s of uranium f l i i o r i d e s am3 t h e r a t e a t vhich t h e r e a c t i o n s proceed. It i s b e l i e v e d tha-i; the a d d i t i o n of U F 6 t o a molten s a l t c o n t a i n i n g UF4 results in t h e formation of d i s s o l v e d f l u o r i d e s of uranium with a .valence intermediate between 4 t - and 6-t . This behavior i s i n d i c a t e d by the fact t h a t q u a n t i t i e s of F2 s u f f i c i e n t f o r the Porrnation of UF5 can be absorbed by molten s a l t containing UF4 without t h e e v o l u t i o n of W G . Similar bt2havior i s a l s o noted i n r e a c t i o n s between W4 and UFG i n t h e absence o f molten s a l t t o y i e l d iriCerinediate

200 fl.uori.des such as U4F17. I-i;could be expected t h a t t h e homogeneous rea c t i o n r a t e would be very r a p i d and t h a t -the alhsorpii.on. r a t e would pi-ribab l y depend upon d i f f u s i o n t o and from t h e i n t e r f a c e . Previous d a t a or? t h e r e d u c t i o n of uranium fluorides i n t e r m e d i a t e betiween W 4 and UF6 i n molten s a l t s do not, e x i s t ; however, r a t e d a t a may be i n f e r r e d from t h e r e d u c t i o n of UF w i t h hydrogen in molten mixtures of LiF and ReF2 performed by Long.' He observed t h a k the ratio of t h e c o n c e n t r a t i o n s of hydrogen and HF i n gas bubbles r i s i n g through the molten s a l t reached equilibrium i n on1.y a few iizcbes. His d a t a also indicai;e only 1% r e duction o f UF4 t o UF3 by a gas stream contai.rting 1% H T i n hydrogen a t pressii.res of J. a t m a t 600'C.

The experimental equipinenl; c o n s i s t e d o f a react,ion v e s s e l i n which molten salt containing UFA could be contacted w i - L h a metered strean of m6, HF, HZ, or ~ 2 ,and NaF t r a p s t o coll-ect U F ~and/or HF i n t h e off-gas (Fri.g. 7 . 5 ) . Two NaF t r a p s were provided downstream of t h e vessel-; one ORFIL-DWG

6 5 - 1794RA

H 2 + HF

SALT

F i g . 7.4..

Continuous Reduction of UP6 by Ii2 i n a Molten S a l t .

ORNL-OWG

4 - - i n NICKEL PIPE

55-3098A

OFF-GAS

REDUCTION VESSEL

F i g . 7.5.

Eq.uipment Used i n Reducttion o:f UFb to UF4 i n a Molter1 Sali;.

t r a p w a s used only- f o r t r a p p i n g UF6 from t h e v e s s e l off-gas during UF6 a d d i t i o n t o t h e molten salt, and t h e o t h e r t r a p w a s used for a l l o t h e r €IF ul?6 absorption. %rie r e d u c t i o n v e s s e l w a s c o n s t r u c t e d from 4-in.diam sched-40 n i c k e l pipe and w a s 26 i n . long. A 3/8-in. nickcL i n l e t l i n e w a s l o c a t e d i n t h e c e n t e r of t h e v e s s e l and terminated 1/4 i n . from t h e bottom of t h e vessel. A 3/&in. € i t t i n g on t h e t o p f l a n g e allowed t h e i n s e r t i o n of a cold, 3/8-in. n i c k e l rod, which was used f o r sampling t h e s a l t . A 3/8-in. off-gas l i n e was connected t o the t o p f l a n g e . The v e s s e l w a s heated by two Nichrome-wire r e s i s t a n c e f i r n a c e s . lor

Three experiments were c a r r i e d out a t 600'C i n which UF6 was i n t r o duced a t t h e r a t e of 1.5 g/rnjn a t a p o i n t 12 i n . below t h e s u r f a c e of a iiiolten L ~ F - z ~mixture F~, containing -0.5 mole $ U F ~ . Tne i n i t i a l s a l t charge c o n s i s t e d of 5320 g of ZrF4, 863 g o f LiF, and 61.8 g o f U F 4 (0.197 g-mole of 1 x 4 ) and had a melting p o i n t of approximately 510'C. Complete absorption of t h e UF6 w a s observed during each of t h e t e s t s , during a which r e s u l t e d i n t h e a'osorption o f a t o t a l of 147 g of period of 98 rnin. During a t y p i c a l run, t h e s a l t charge from t h e previous run was heated t o 600°C and sparged with N2 f o r 15 illin a t t h e r a t e of lCi0 cm3/min (STP), a f t e r which a s a l t sample was taken. The s a l t was t h e n sparged with WF a t the r a t e of 0.5 l b / h r f o r 1. h r and with N2 f o r 1.5 min, a f t e r which a second s a l t sample was taken. Uranium hexafluoride was then bubbled i n t o t h e s a l t a t a r a t e of l . 5 g/min for a s p e c i f i e d I.ength of time, with t h e v e s s e l off-gas passing through an NaF bed used e x c l u s i v e l y during t h i s period. The s a l t was then sparged with M 2 for 1 15 inin and sampled. The s a l t was t h e n sparged with H2 a t the r a t e of 95 c m 3 / m i n (STP) f o r 30 rnin and s m p l e d , a f t e r which t h e H2 sparge was continued f o r an a d d i - t i o n a l 30 min. Two questions r e l a t e d t o t h e experimental work a r e of primary i n t e r e s t . These a r e (1)t h e f r a c t i o n of mi76which was absorbed by t h e mol-ten s a l t and ( 2 ) t h e valence of the uranium i n t h e :resul.ting mixture. It w a s conc1.uded t h a t , wfthin t h e accuracy of t h e experimental. data, by t h e molten s a l t had occurred. No compl.ete absorption o f t h e uranium w a s found. on t h e NaF t r a p used during t h e UF6 a d d i t i o n p e r i o d . %he c o n c e n t r a t i o n o f UF6 i n t h e s a l t sample taken after [Eij a d d i t i o n was below t h e l i m i t o f detectLon of 0.05 .I& %. Reduction of' t h e u.raniim t o Wr, probab1.y occurred during t h e a d d i t i o n of' I J F h by t h e r e a c t i o n of t h e intermediate f l u o r i d e s with n i c k e l from the v e s s e l wa1.l. From t h e s e t e s t s it appears t h a t UF6 could. b e r a p i d l y absorbed by molten f l u o r i d e s a l t containing a1Jou.t 1. w t $ UF4 a t 600°C and t h a t the ini;erinedj_ate f l u o r i d e formed could be reduced w i t h hydrogen t o U F 4 . Subsequent s t u d i e s zrc recommended t o protride more q u a n t i t a t i v e data f o r engineering design; however., t h i s form of recombiiia.tion of UF,; with t h e p u r i f i e d c a r r i e r ;salt w i l l be i n d i c a t e d on all. subsequent flowsheets

202 Continuous F l u o r i n a t i o n of a Molten S a l t Since t h e presence of inaniwn i n t h e d i s t i l l a t i o n s t e p t o s e p a r a t e t h e c a r r i e r s a l t from t h e f i s s i o n grodiucts would cause unnecessary complic a t t o n s , it i s removed continuously i n a p r i o r f l u o r i n a t i o n s t e p . Previous experience with t h e remova,l. of uranium from molten s a l t by f l u o r i n a t i o n includes t h e o p e r a t i o n of t h e Moltell-Sa1.t F l u o r i d e Volati.li.ty P i l o t P l a n t ai; ORNL. I n t h i s f a c i l i t y , b a t c h f 1uorina"cions compleLely v o l a t i l i z e d t h e uranium as UF6, which allowed i t s subsequent p u r i f i c a t i o n and recovery by a b s o r p t i o n and c o l d trappiiig Observed c o r r o s i o n 7.n t h i s f a c i l i t y w a s severe b u t acceptable i n a b a t c h process of t h i s s o r t . However, it would be i n t o l e r a b l e i n a co:nti-nu.ous u n i t , o r i n any u n i t w i t h enough c a p a c i t y t o handle t h e processing stream f o r a n W B R . A p o s s i b l e s o l u t i o n t o t h e c o r r o s i o n problem i s t h e o p e r a t i o n of t h e i"1uorinaLion v e s s e l , p r e s e n t l y envisioned as a i,ower, w i t h a l.ayer of f r o z e n s a l t on t h e v e s s e l w a l l . Experience w i t h t h i s type of system was obtained w i t h ba-Lch f 3.uorinat:i.oii~ made a t 44rgome National. Laboratory' i n suppor-'i of t h e m o l t e n - s a l t f l u o r i d e vo1ai;ility process. Successful. t e s t s were a l s o made a t OHNL u s h g o?m-?:.cheatring t o provide t h e i n t e r n a l heat generation, where i t w a s found that a gas flow could b e maii-ttai.n.ed through an unheated l i n e which e n t e r e d t h e f l u o r h a t o r v e s s e l a t a p o i n t below t h e moltensaLt s u r f a c e when a f r o z e n s a l t l a y e r w a s present on the fluorrinator w a l l . i n app3.ication t o t h e MSRR f l u o r i n a t o r , i n t e r n a l h e a t generation w i l l be provided by t h e f i s s l o n product decay h e a t . E x p e r h e n t a l . s t u d i e s of continuous f l u o r i n a t i o n of imYLen sal'i. a r e being made i n a l-in.-dlaa? n i c k e l column w i t h a s a l t depth of 4-8 i n . No p r o v i s i o n i s being made i n the presenl; experimental. work f o r corrosi.on p r o t e c t i o n by a f r o z e n l a y e r of s a l t (Fig. 7 . 6 ) . F l u o r i n a t i o n t e s t s i n which 15 cm3/min of molten s a l t (NaF-IAF-ZrFs 1 c o n t a i n i n g 0 . 5 w t '$ U11'6 w a s contacted c o u n t e r c u r r e n t l y with 70 cm3/min o f F2 (STP) a t 400Â°C showed reimval. of uranium from t h e s a l t a t 95 t o 99.4% e f f i c i e n c y during a I - h r period of continuoils o p e r a t i o n . Material. balances were complic a t e d by t h e i n e v i t a b l e c o r r o s i o n of t h e n i c k e l v e s s e l . Complete rernoval~ oâ&#x201A;Ź uranium from t h e sa1.t wi.th no c o r r o s i o n would y i e l d , f o r t h e above cond i t i o n s , a m6 c o n c e n t r a t i o n of 17.6 mole % iii t h e Off-gas. Observed conc e n t r a t i o n s Yanged as high as 35 mole '$ uh'6. These r e s u l t s i n d i c a t e t h a t subsequent development can be expected t o p l - 0 d u . c ~ acceptable r e c o v e r i e s of uranium by coniinuous f l u o r i n a t i o a .

C1iromiu.m Fluoride T r a m i n g A-L t h e conc3-insion o f t e s t s on t h e MSRE, uranium w i l l be recovered from t h e f u e l s a l t as UF6 'by spargiilg t h e s a l t w i t h F 2 . F l u o r i d e s of chrorniim wi1.1. be present i n t h e f u e l s a l - t as a r n s u l . t of c o r r o s i o n of r e a c t o r pipiiig arid. of' equipineat used for hydrof l u o r i n a t i o n o r f l u o r i n a t i o n of t h e s a l t . A p o t e n t i a l pmi,lem associated. w i t h . t h e recovery of t h e uran.i.um i s t h e presence of v o l a t i l e f l u o r i d e s o f clii-orn.iimi (CrF4 and CrF5 )

203 ORNL-DWG

65-9354A

INFRARED A N A L Y Z E R FOR lJF6 Ci\lAl.YSlS

OFF .-GAS

NICKEL FLUORINATOR 1 - i n diom 72-lrl long

F i g . 7.6. Equipment f o r Removal of IJraniurfl from Molten S a l t by Continuous Fluorination.

i n %he f l u o r i n a t o r off-gas; t h e s e f l u . o r i d e s carmot only cori-Laainate the UF6 product b u t a l s o render equipment i n o p e r a t i v e by d e p o s i t i o n i n l i n e s , valves, e t c . A study has been completed which w i l l permit the design o f a. t r a p p i n g system f o r removing t h e s e f l u o r i d e s froni t h e off-gas, which w i l l also c o n t a i n UT6 and 3 ' 2 . Experiraents were c a r r i e d out i n which 1 l i t e r / m i n of F2 (STP) was sparged through a molten NaF-LiF-ZrF4 mixture a t 650째C which cori-tain~icl 0.5 t o kt w t $ ~ r ~ 3Tne . resul-Ling o:W-gas c o n t a i n i n g fl.uorine and Volat i l e f l u o r i d e s of chromium t h e n passed l;hrouy'ii beds of' p e l l e t e d NaF a t 400째C f o r removal of chronlim f l u o r i d e s . In some t e s l ; : ; , a Ul!6 flow of 100 cm3/min was added t o t h e Fz.

It can be concluded. t h a t (I) f i x e d beds of MaF a t C1,OO"C a r e effec.1;iv-e i n removing f l u o r i d e s of chromium from a gas s t r e a n which also c o n t a i n s UF6 and F2; ( 2 ) p e l l e t e d NaF having a surface a r e a of 0.074 m2/g and a void f r a c t i o n of 0.277 i s s u p e r i o r t o m a t e r i a l having a, s u r f a c e area of 1 m2/g and a void f r a c t i o n of 0.45, and has an e f f e c t i v e c a p a c i t y of about 20 g of chromium p e r 100 Q of NaF; ( 3 ) uranium losses t o t h e 400째C NaF bed of leas t h a n O.Ol.$ are achievable when working w i t h a gas strewn t h a t c o n t a i n s 0.4 mole of CrF5 per mole of UF6 i n Fz.

A preliminary design study has been made or" a conceptual processing p l a n t t o t r e a t i r r a d i a t e d l ' u e l and f e r t i l e s t r e m s from t h e 1000-MSJ ( e l e c t r i c a l ) MSRR described i n t h e s e c t i o n "Molten-Salt Breeder Reactor

204 Design 8 . t u d . i e s " of t h i s r e p o r t . The study evaluated t h e engineering f e a s i b i l i t y and c o s t s f o r a p l a n t t h a t operated continuously as an i n t e g r a l part of t h e reactor system, being I.ocated i n . -two cel.1-s a d j a c e n t t o t h e reac:i;o:e c e l l . The p l a n t w a s designed to t r e a t 15 ft3/d.ay of f u e l sa1.t and 105 fL3/day of f e i ; - t i l e s a l t . The f u e l sa1.t was a n LiF-BeFZ (69-31 mole $) mixture containing the fj-ssionabl-e 3-331JFi,; f c r t i l e salt war, a 71.-29mole % mixture of LLF-TWL,. 'Yne l i t h i u m coinpoilent of cach stream w a s enriched. t o about 99.995 a t . $ 7 L i . The processing cycle was s e l e c t e d t o give ilie optiniwn combination o f f u e l c y c l e c o s t and breeding gain. Description of Fuel Process The primary o b j e c t i v e of t h e fuel. process i s t o recover uranium ami c a r r i e r salts suf f i c i e n t ly decontaminated from fis s i on and. c o r ~ oi so n products s o t h a t t h e r e a c t o r has an a t t r a c t i v e breeding potential.. The recovered m a t e r i a l s are recycled t o t h e r e a c t o r am?. t h e f i s s i o n producis a r e discarded. Only f o u r major o p e r a t i o n s a r e r e q u i r e d i o accomplish t h i s f o r t h e f u e l stream: f l u o r i n a t i o n , s o r p t i o n of U F 6 , vacii.u.m d i s t i l l a t i o n , and s a l t r e c o n s t i t u t i o n . These o p e r a t i o n s a r e shown schematically i n F i g . 7.1.

As i.t e n t e r s t h e processing c e l l , f u e l sall.t i s only a few seconds removed from t h e f i s s i o n zone and i.s extremely r a d i o a c t i v e . The stream i s del3yed Cor about 36 h r b e f o r e f l u o r i n a t i o n t o allow t h e h e a t generat i o n r a t e t o decrease t o a p o i n t t h a t temperature c o n t r o l i n t h e flu.oi-ina-t,or i s made e a s i e r . The curve i n Ftg. ?.'7 shows Lhe g r o s s heat gene?..a t i o n r a t e of t h e f u e l s a l t . Tlne molten s a l t flows i n t o 'ihe t o p of a column and i s contacted by a countercurrent stream of f l u o r i n e , which s t r i p s out t h e uraniurn according t o t h e r e a c t i o n

m4 +

508-550 O C

>m6

F i s s i o n products Ku, Tc, Nb, C s , Mo, and Te are a l s o v o l a t i l i z e d and accompany the u F 6 . The system, consf-string of molten LiF-HeF2-UF4, f i s s i o n produ.cts, and. elemental f l u o r i n e , i s ex-tremely c o r r o s i v e t o t h e w a l l s of 'ihe fl.uorinator, reqiiiring c l e v e r desri.gin i f a s i g n i f i c a n t l . j _ f e t i m c i s t o be obtained. It i s proposed t o j a c k e t t h e fl.uorinator wi-Lii a coolant t h a t wi.1.1.. maintain a 0.5- t o 0.75-iu.-thick la,y-er of frozen sal?; on t h e i n n e r s u r f a c e of t h e column t o s h i e l d t h e wall. from t h e molten ~ a 1 . t . ~A schematic d i a g r m of t h e f l u o r i n a t o r i s shown i n Fig. 7.8. The gas s trearii leaving t h z f l u o r i n a t o r passes through a sorptioi. sy stem composed of temperature-controllzd beds of NaF and MgF2 p e l l e t s 'The f i r s t s e c t i o n of the NaF bed i s h e l d a t about 400째C and. sorbs most of t h e f i s s i o n products; t h e second section o f t h e bed ai about 100째C

OHNL-DWG

t5-9394RA

n c +

I c .L

-2 + m

< ILz

d c

cc w z w

TIME AFTER D I S C H A R G E FROM R E A C T O R ( d a y s )

F i g . 7.7. F j s s i o n Product Decay Heat i n PGBR Fuel Stream f o r a 10GOICJ ( E l e c t r i c a l ) iieac-tor

s o ~ b stechnetium, part of t h e molybdenum, and W6, and allows -the ~ e maining f i s s i o n products t o pass. Upon h e a t i n g from 100 t o ~'oo째C, t h e second s e c t i o n of t h e sor'ner releases molybdenum, -teclmetiwn, a n d . TFG, which passes through MgFz for r e t e n t i o n or" technetium while allowing m6 t o p a s s . Ur%nium h e x a f l u o r i d e i s frozen i n cold t r a p s and r e t a i n e d for recycle -t;o t h e r e x - L o r

Uraniwn-free s a l t flows from the f l u o r i n a t o r i n t o a continuous d i s t i l l a t i o n u n i t , which i s o p e r a t e d a t about 1 nun Hg pressure and 1000째C. Under t h e s e c o n d i t i o n s , it i s possi'ale t o d i s t i l l LiF an.d. ReFz from t h e b u l k of the r"issioi1 products.' Iiare-earth f i s s i o n products are much less v o l a t i l e t h a n l i t h i u m or b e r y l l i t u n f l u o r i d e , allowing ;z good s e p a r a t i o n t o be achieved.. Zii-conium f l u o r i d e , however, i s s u f f i c i e n t l y v o l a t i l e t h a t t h i s f i s s i o n product wi1.l contaminate t h e LiF-BeFa pro&uct;.

I n t h i s study t h e vacuviri s t i l l was a 2 . 5 - f t - d i m by 4-ft-high v e s s e l c o n t a i n i n g a bank of c o o l i n g t u b e s over most of its h e i g h t . A- coudensing s u r f a c e a t t h e t o p condensed and c o l l e c t e d the overhead product. To i n i t i z t e t h e o p e r a t i o n t h e i n t e r i o r of t h e s t i l l - i s charged w i t h I+ f t 3 of molten LiF; t h e s t i l l i s evacuated and brought t o temperature, and s a l t from t h e f l u o r i n a t o r is allowed t o flow i n t o t h e pool of molten XF. Temperature i s c o n t r o l l e d so t h a t liquid i s vaporized a t -the same r a t e a t which it e n t e r s t h e s t i l l . There i s no bottom discharge, so the stil.?. volume remains c o n s t a n t . P-ccor&ingly, t h e c o n c e n t r a t i o n of f i s s i o n

206 O R N L - DWG 6 5 - 3 0 3 7 R P

Y F , ,

UF,,

F.P. TU SORPTION SYSTEM

DE ENTRAINMENT S ECTlON

’/2

WALL OF SALT TO 314 in THICK

-I ”UEL S P LT b

DRAIN

NaK

F i g . 7.8. Continuow :Fluorirla”ir w i k h Frozen S a l t W a l l for Corr o s i o n Protection.

207

products s t e a d i l y i n c r e a s e s i n t h e 4 f t 3 of LiF. After about 67 days' o p e r a t i o n t h e accumulated heat generation r a t e ( s e e Fig. 7.9) has become so g r e a t t h a t the h e a t removal c a p a b i l i t y of t h e c o o l i n g system i s reached; t h e s t i l l c o n t e n t s a r e t h e n drained t o waste s t o r a g e , and t h e o p e r a t i o n i s repeated. Heat La removed by f o r c e d c i r c u l a t i o n of NaK on t h e s h e l l s i d e of t h e tubes.

The concentration f a c t o r f o r r a r e - e a r t h f i s s i o n products in t h e st.j-11i s abo-ut 250. The f r a c t i o n of t h e process strean, which i s almost e n - t i r e l y 7LiF, discarded a t t h i s p o i n t is s l i g h t l y less t h a n 0.4%" Because of t h e v o l a t i l i t y of ZrE'r,, an a d d i t i o n a l d i s c a r d of the d i s t i l l a t e i s r e q u i r e d t o purge t h i s f i s s i o n product. A s much as a 5% throwaway might be necessary i n this type of o p e r a t i o n . A t t h e time of this s t u e , da.ta were not a v a i l a b l e t o assess t h e e f f e c t o f i n c r e a s i n g f i s s i o n product c o n c e n t r a t i o n i n -the s t i l l on r e l a t i v e v o 1 a t i l i t ; i e s . Consequently, t h e overall decontamination f a c t o r (UF) of the d i s t i l l a t e cannot be p r e d i c t e d a c c u r a t e l y , b u t i t i s b e l i e v e d t h a t a DF of a t l e a s t 100 can 'oe a t t a i n e d .

ORNL- DWG 6 5

- 4821 R 2 A

-2 c

1 0 ~

0 I-

a f0 t-

0 AT

2.85 days

IO'

(02

TIME A F T E R D I S C H A R G E F R O M R E A C T O R ( d a y s )

I 03

F i g . 7.9. Heat Generation Rate i n the LiF Pool. XesuZtirig from F i s s i o n Product AeemuZation i n the S t i l l .

208 The f i n a l s t e p i n f u e l processing i s r e c o n s t i t u t i o n t o make a s u l t a b l e f e e d f o r t h . e r e a c t o r . The LiF-ReF2 d i s t i l l a t e i s admit-Led t o a r e d u c t i o n co1.imn containing molter, (-600째C) LiF-BeF2-UT4 t h a t i s approximately t h e correct fuel composition. Concurrently, gaseous from t h e col-d t r a p s i.s introduced near t h e bottom of t h e col.imn, and hydrogen gas i s a d m i t b d a t a p o i n t a li-Lt1.e f a r t h e r up t h e col.imii. The m6 abSOr"r,S i n Lhe molten s a l t t o form a n intermediate f l u o r i d e of uranium such as UF5, which r e a c t s w i - L l i H;! according t o t h e r e a c t i o n

UF5

+ -21 H2-

UF4

IFF

Makeup UF6 from t h e b l a n k e t process a n d makeup IZF and BeFz a r e added a t this poinl;. The r e c o n s t i t u i c d f u e l i s s e n t t o 'die r e a c t o r core t o comp l e t e t h e f u e l procesaine c y c l e .

Dcscription of F e r t i l e Process The f e r t i l e s t r e m process c o n s i s t s only of contlnuous f l a o r i n a t i o n and UF6 p i i r i f i c a t i o n by s o r p t i o n . 'l'he operaLion i s amlogous Lo the corresponding fuel- s-trea.m o p e r a t i o n b u t at; a higher volumetric r a t e . 'The c y c l e t i m e of t h e f e r t i l e stream i s purposely kept s h o r t (20 t o 25 days) t o keep a low iiranium c o n c e n t r a t i o n i n t h e bla.n.ket,, thereby keeping -the f i s s i o n r a t e low. The low f i s s i o n r a t e ensures a low f i s s i o n p m d u c t accwnula'iion r a t e s o t h a t i t i s unnecessary t o remove them on the same c y c l e as uranium. I n ?act,, a 30-year d i s c a r d c y c l e o f t h e b a r r e n f e r t i l e stream i s a s u f f i c i e n t purge r a t e Tor f i s s i o n pi-oducts. Excess u F 6 over that, required t o r e f u e l t h e core i s sold.

Waste Treatment

Four waste streams r e q u i r i n g s t o r a g e leave t h e processing f a c i l i t y : (1)aqueous waste from t h e K O 3 scrubber, ( 2 ) NaF and MgF2 sorbent from t h e Ub'6 p u r i f i c a t i o n system, ( 3 ) mol.ten-sa1-L resridue from t h e disti.7-lation u n i t , and ( 4 ) moltcn s a l t from t h e f e r t i l e - s t r e a m d.iscard. The aqueous waste c o n i ~ sfrom vent-gas scrubbing and i s s m a l l i n volrume; i t was assumed t h a t t h i s stream cou1.d be combined w i t h r e a c t o r aqueous wastes f o r s t o r a g e . The t w o m o l t e n - s a l t was'ws are s t o r e d i n uiderground tanks, and tiie p e l l e t i z e d s o r b e n t s a r e s t o r e d i n cyI.indrica.1. c o n t a i n e r s i n an underground v a u l t . Forced draft coolri.ng i s provided f o r t h e s e 'ihree s t o r a g e areas.

This stiidy includes a charge f o r 30-year i n t e r i m s t o r a g e of t h e m o l t e n - s a l t wastes and for 5-year i n t e r i m s t o r a g e o f t h e solid waste. Perpetual. s t o r a g e beyond t h e s e times w 3 s iiot considered.

209

Off-Gas Treatment Most of t h e off-gas I'rorn t h e process comes from t h e continuous f l u o r i n a t o r s . Although f l u o r i n e i s recycled, a small amourit i s b l e d o f f t o purge gaseous f i s s i o n products. The off-gas i s s c n h b e d with a n aqueous c a u s t i c s o l u t i o n , f i l t e r e d , and rlischarged t o t h e atmosphere. Summary o f C a p i t a l and. Operating Costs The design study included. an e s t i m a t i o n of c a p i t a l and o p e r a t i n g c o s t s f o r t h e i n t e g r a t e d processing p l a n t Space requirements and c o s t s w e r e estirnated f o r a t y p i c a l l a y o u t (Fig. 7.10) a d j a c e n t t o t h e r e a c t o r system. Each item of major equipment w a s designed t o t h e extent t h a t a reasonably a c c u r a t e e s t i m a t e of i - t ~ c o s t couLct be made; t h e costs of a u x i l i a r y items, such as u t i l i t i e s , piping, instrumentation, e l e c t r i c a l connections, i n s u l a t i o n , and sampling, were e s t i m a t e d by applying approp r i a t e f a c t o r s t o process equipment c o s t s . e

Direct; operatirig c o s t s were estiiniat;ed f o r l a b o r and supervision, consurr-ed chemicals, u t i l i t i e s , and maintenance materia1.s. These c o s t s and. c a p i t a l c o s t s a r e summarized i n Table '7.2. ORNL

- DWC;

65-4804RA

HEAT EXCHANGER REACTOR POWER

FERTILE M A K E - U P F L U O R IN A T 0 R

F i g . 7 -10. Reactor Inteegrated Processing Plant; Preliminary Layout.

210 Processing Cost The c o s t s summariAed i n Table t h e Fuel cycle c o s t when t h e f i x e d t h e p l a n t f a c t o r i s taken a t 80%. lO$/year for depreciation, l$/year

7.2 c o n t r i b u t e about 0 . 2 mill/kwhr t o charges are amortized ai, l@/year am1 The amortizatioii charge iiicludes for taxes, and l$/year for insurance.

Tabl.: 7.3. Cost of an I n t e g r a t e d Processing P h o t f o r a I O O O - f i v ( E l e c t r i c a l ) Molten-Salt Breeder Reactor

Fixed C a p i t a l C o s t s ( $ ) Bui ].ding space

1,I. 30,900

Proc e ss e qui.prnen'i

1,734,200

Services arid u t i l i t i e s

-?1 -.-

788,100

inierrim was-k s t o r a g e

648,300

5,301,500

Total Inventory

COSLS~

($)

Fuel s a l t c a r r i e r

89,460

Fertile salt

69,200

N a K coolant

40,000

To ial

198,660

Direct Operating Cos1;s ( $ / y e a r ) Supervision and labor Chemicals

7'0,390

Was Le contai ners

2%,270

U t i lit i e s

Mainienance material s Total a

399,600

Exc lude s fissri 3.e materia 1.

80,300 209,230

787,790

211 References

1. C . D. Scott and W. L. C a r t e r , Prel.im.i.nary Design S t u Q of' a Continuous Fl.uorination-Vac:uwn E i s t i l l a t i o n System f o r Regenerating Fuel and F e r t i l e Streams i n a Molten S a l t Breeder Reactor, OHNL-3791 (January 1.9661

2. M. J. Kelly, ORNL, unpublished data (May 21, 1965). 3.

G. ~ o r i g , S t a b i l i t y of U F ~ ( i n preparation).

B. P. PEl.ford e t a]..,

Ind. Eng. Chem. 5 3 , 357 (196l). I

R . 1.J. Kessie e t a l . , Process Vessel Design Tor Frozeri-Wall CorxLainmnerit of Fused S a l t , ANL6377 (1961).

I _

6. M. J. Kelly, Removal of Rare E a r t h F i s s i o n Products frora Molten S a l t

Reactor Fuels by D i s t i l l a t i o n , paper presented a t 1 1 t h annual meeting of Aaeri.can Nuclear Society, G a t l i r i b u r g , Terui. (Jme 2l-2.1, 1965).

2w OAK RIDGE NATIONAL LABORATORY

MOLTEN-SALT REACTOR PROGRAM FEBRUARY i, 1366

R. B. BRIGGS, DIRECTOR P. R. KASTEN,' DEPU';'I 31RECTOR McDONALD:' Ash: D I R E C l O R

D R R

w. B.

MSRE OPERATIONS PAUL R. KASTEN.

COMPONENT A N 0 SYSTEMS DEVELOPMENT

P. N. HAUBEhREICH

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L - L d

METALLURGY

REACTOR CHEMISTRY Y. R. CRIMFS'

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5. BETTIS

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R. H. GUYMON J. H. CROWLEY P. H. HARLEY V. D. HOLT 7 , L , HU3SCN A. I. KRAKGVIAK t:. P. PAYNE 5.i. ROLLER ii.ST?FFY W. C. ULRICH T A2NWlhE W. H DUCTWORTH J. 3. EMCH H. GUlNN T. G. H I L L 5. C.H U R T 1 J. C. JORDAN v i J MILLER L. E. PEN.TON W.E.RAhUEY R. SMITH, JR. J. L. STEP? J. L. UNDERWOOD 5. 9. WEST J. E. WilLFE

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JE. M. L . BAKER COMPERE

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C. H. GABBARD'. H. 8. PIPER J. A. WATTS

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2 15

Om-3936

UC-80 - Reactor Technology INTERNAL DISl%IBUTION

1. G. M. Adanson 2. L. G. Alexander 3 . C. F. Baes 4 . J. 14. B a k e r 5. S . E. B e a l l 6. E. S. B e t t i s 7. D. S. B i l l i n g t o n 8. F. F. Blankenship 9. R. Blumberg 10. H. F. Baman 11. A. L. Boch 1 2 . E. G. Bohlmann 13. C. J. Borkowski 14. G. E. Boyd 15. M. A. Bredig 16. E. J. Breeding 17-26. R. B. Br-iggs 27. 3'. R. Bruce 28. G. H. Burger 29. S. Cantor 30. D. W. Cardwell 31. W. L. C a r t e r 32. E. L. Compere 33. 5 . A. Conlin 34. W. W. Cook 35. L. T. Corbin 36. G. A . C r i s t y 37. J. L. Crowley 38. F. L. C u l l e r 39. J. M. Dale 40. D. G. Davis 41. W. W. Davis 42. J. H. D e V m 4 3 . R. G. Donnelly 44. D. A. Douglas 45. N. E. Dunwoody 46. J. R. Engel 4.7. E. P. Epl.er 48. W. K. Ergen 49. D. E. Ferguson 50. A. P. Fraas 51. J. H Frye, Jr. 52. C. â&#x201A;Ź1. Gabbard 53. W. R. Gall 54. R. B. Gallaher 35. R. G. G i l l i l a n d 56. W. R. G r i m e s

..- ....

57. A. 58. 3 . 59. I?. GO. C. 61. P.

62. 63. 64. 65. 66. 67. 68. 69. 70.

P. R.

M. E. H.

P. A. A. 71. T. 72. H. '73. W. '74-83. P. 84. R. 85. M. 86. M.

8'7. C.

88. T.

89. 90. 91. 92.

H. A. J. C.

9 3 . C.

94. T. 95. R. 96. R . 97. M. 88. H. 99. F. 100. W. 101. H.

102. W.

103. H. 104. C. 105. E. 106. C. 107. W.

108. R. 109. K.

110. J. 111. M. 112. W.

G. G r i n d e l l

13. Guymon

H. Harley S. I I a r r i l l N. Ilaubenreich G. Herndon F. Ilibbs ( Y - 1 2 ) R. H i l l C. Hise W. I I o f h a n D. Ko1.t P. Ilolz Hollaender S. Householder L. Bud.son Inouye H. Jordan R. Kasten J. Ked1 T. K e l l e y J. Kelly R. Kennedy W. X e r l i n T. Kerr I. Krakoviak W. Krewson E. Lamb E. Larson A. Lincoln B. T,ind:tuer S. Livingston I . Lundin G. MacPherson C. Maicnschein R . Martin E . McCoy B. McDonald F. McDuffie K. McGlothlan C. Miller A. M i l l s R. Mixon L. Moore Z. Morgan C. Moyers L. Nelson R. Osborn

216

11.3-114.R. B. Parker 115. L. F . P a r s l y 1-16. 117. 11G. 1.3.9. 120. 121. 122. 123.

P. P a t r l a r c a

H. R. Payne D . Phri.llips W. B. Pfke H. B. P i p e r B. E. P r i n c e J . L. Kedford M. Richard.son 124. E. C . Roberkson 125. H . C . Rol.l.er 126. M. W . Roscnthal 1-27.H. C . Saxage 128. A. W . Savolainen 129. D . S c o t t 130. 11. E. Seagren 131.. J. H . S h a f f e r 132. E . D. Ship]-ey 1-33.M. J. Skinner134. G. M. Slaugh'ier 135. A. N . Srnikh 136. P. G. Smi.th 13'7. A. H. Snel-1. 1.38. W. F. Spencer 139. I. Spiewak 140. R . S t e f f y 1A1. C . E. Stevenson

14%. C . D . Susano 143. J . K. Tallackso:c* 14.1+- E. H. Taylor 145. R . E. Thoma 146. G. M. Tolson 147. L). B. Trauger 148. R. W . Tucker 149. W . C . U l r i c h 150. D. C . Watkin 151. G. M. Watson 152. E. H. Webs-'ier 153. A . M. Weinberg 154. J. R. Weir 155. J. H. Wes-tsik 156. M. E . Whatley 157. G. C . W i l l i a m s 158. J. C . White 159. L. V . Wilson 160. K . J. Yost 161..G. J. Yomg 162. Biology L i b r a r y 163-164. Reactor D i v i s i o n L i b r a r y 165-169. ORNIL - Y - 1 2 Technical L i b r a r y Document Reference S e c t i o n 170-172.C e n t r a l Research L i b r a r y 1'73-207. T,aboratory Recordk Department 208. Laboratory Records , O m L R . C . EXTERNAT, DJSTRLBU'l2I O N

209-210. D. 3'. Cope, Atomic Energy Commission, OR0 21.1..C . B. Deering, Atomic Energy Commissi.on, OR0 212. R. G. Garrison, Atomic Energy Commission, Washington 213. M. Shaw, At0mj.c Energy Commission, Washington 214. E. E. S i n e l - a i r , Atomic Energy Commission, Washlngton 215. W. L. Srnalley, Atomic Energy Commissri.on, OR0 27-6. J . A. Swartout, 270 Park Avenue, New York 17, New York 2l7. M. J. Whitman, Atomic Energy Commi.sston, Washington 218. Research and Development, Division, AEC, OR0 219- 549. Given d i s t r i b u t i o n as shown i n TID-4500 under Reactor Technology category (75 copies - CFSTI)