ORNL-TM-3863 by Jon Morrow

HOME HELP

ORN 1-TM-3863

DESIGN AND OPERATION OF A FO RC ED-CI RC ULATlO N CO RROSI0N TEST FACILITY [ MSR-FCL-1) EMPLOYING HASTELLOY N ALLOY AND SODIUM FLUOROBORATE SALT W. R. Huntley P. A. G n a d t

This report was prepared as an account of work sponsored by the United States Government. Neither the United States nor the United States Atomic Energy Commission, nor any of their employees, nor any of their contractors, subcontractors, or their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness or usefulness of any information, apparatus, product or process disclosed. or represents that i t s use would not infringe privately owned rights.

ORNL-TM-3863

C o n t r a c t No.

W-7405-eng-26

Reactor Division

DESIGN AND OPERATION OF A FORCED-CIRCULATION CORROSION TEST F A C U I T Y (MSR-FCL-1) EMPLOYING HASTEIIz;OY N ALLOY AND SODIUM F L U O R O B O M SALT

W. R. H u n t l e y

1 1

P. A . G n a d t

NOTICE . . This report -5 prepared I S aCCOUnt Of WorK sponsored by the United States Government. Neither the United States nor -the United States Atomlc Enerw Commlrsion, nor any of their employees, nor m y of their contractors, subcontractors, or thek employees, nukes any warranty. express or implied. or mUmM m y legal Uabjlity or responsibility for the accuracy, cornplotenens or ussfulnera of m y information, appsratus, product or procow disclosed, or represents that its WO would not infringe privately owned righta.

JANUARY 1973

OAK RIDGE NATIONAL LABORATORY Oak Ridge, Tennessee 37830 operated by

UNION CARBIDE C O F P O W I O N U.S.

f o r the ATOMIC ENERGY COMMISSION

iii

CONTENTS

................................................ ABSTRACT ...................................................... 1. INTRODUCTION .............................................. 2 . DESIGN AND FABRICATION .................................... 2.1 Design Criteria .....................................

ACKNOWLFDGMENT

.......................... 2.3 Detailed Design and Fabrication ..................... 2.3.1 Heater ....................................... 2.3.2 Cooler ....................................... 2.3.3 S a l t pump .................................... 2.3.4 S a l t sampler ................................. 2.3.5 BF, system ................................... 2.3.6 Fill and d r a i n tank .......................... 2.3.7 Corrosion specimen design .................... 2.3.8 E l e c t r i c a l system ............................ 2.3.9 Instrumentation and control .................. 2.4 Quality Assurance ................................... 3 . OPERATING EXPERIENCE ...................................... 3.1 Heat Transfer Performance of Sodium Fluoroborate .... 3.2 BFa Handling ........................................ 2.2

General Design Information

3.3 S a l t Pump Operation ................................. 3.4 Corrosion Specimen Removal 3.5 salt Sampling 3.6 -S of Corrosion Results

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

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

........................ CONCLUSIONS ................................................... FUXOMMENDATIONS ............................................... APPENDIX A . MSR-FCL-1 FLOWSHEET .............................. APPENDIX Be MSR-FCL-1 CONTROL SYSTEM DESCRIPTION AND OPERATING PROCEDURES FOR U N A " D E D OPERATION ............ APPENDIX C . MSR-FCL-1 SALT SAMPLING PROCEDuEiE ................

v 1 1

2 2

9 9 9 12

14 17 19 19 19 22

23 24 27 29 36 41 44 45 45 47 49 51 63

The f a b r i c a t i o n and operation of the test loop were the j o i n t r e s p o n s i b i l i t y of t h e ORNL Metals and Ceramics Division and t h e ORNL Reactor Division.

The authors wish t o thank the many personnel who

aided i n the design, i n s t a l l a t i o n , operation, and postoperational

examination of t h i s t e s t . Special thanks are extended t o t h e following personnel who were instrumental i n t h e success of t h e experiment. H. E. McCoy, Metals and Ceramics Division, and R. E. MacPherson,

Reactor Division, f o r t h e i r guidance of t h e test program. J. W. Koger, Metals and Ceramics Division, f o r metallurgical analy-

sis throughout the program. H. C. Savage, Reactor Chemistry Division, f o r guidance of loop

operation during t h e l a t t e r portion of t h e test period and f o r t h e Control System Description of Appendix B. E. J. Breeding, R. D. S t u l t i n g , and L. C. W l e r , Reactor Division,

f o r t h e i r contribution t o t h e detailed design of t h e system.

' U

DESIGN AND OPERATION OF A FORCED-CIRCULATION CORROSION TEST FACILITY (MSR-FCL-1) ENF'LOYING HASTELLOY N ALLOY AND SODIUM FLUOROBORA~SALT

W. R. Huntley

P. A. G n a d t

ABSTRACT

. )

A forced-circulation loop (MSR-FCL-1) was assembled and operated t o evaluate the compatibility of standard Hastelloy N with sodium fluoroborate-sodium fluoride e u t e c t i c ( NdF4-8 mole $ NaF) coolant salt a t operating conditions expected i n t h e Molten-Salt Reactor Ihperiment coolant c i r c u i t . The salt velocity i n lf2-in. -OD, 0.042-in. - w a l l tubing was nominally 10 fps. Hastelloy N corrosion specimens were exposed t o t h e circulating salt a t temperatures of 950, 1030, and 1090째F. The test has operated more than 10,000 h r a t these conditions and tests are continuing. This report is mainly concerned with t h e design, fabrication, and operation of t h e f a c i l i t y . Special problems related t o accommodating t h e BFS vapor pressure of t h e salt were resolved, and t h e sodium fluoroborate demonstrated heat t r a n s f e r c h a r a c t e r i s t i c s t h a t could be approximated by conventional correlations such as the D i t t u s Boelter equation. Corrosion rates generally decreased with operating time; f o r example, t h e lowest cdrrosion rate observed f o r the LOgO'F corrosion specimens during a 2900-hr t e s t i n t e r v a l w a s equivalent t o 0.0003 i n . of uniform material removal per year. Keywords: molten salt, corrosion, sodium fluoroborate, Hastelloy N, design, operation, centrifugal pump, mass t r a n s fer, heat t r a n s f e r , M S k , unattended operation. ~

1. INTRODUCTION

The sodium fluoroborate (NaBF4-8 mole $ NaF) salt mixture i s of i n t e r e s t as a coolant f o r the secondary c i r c u i t of molten-salt reactors because of i t s low cost (-$O.5O/lb)

(725OF).

and r e l a t i v e l y low melting point

Screening tests i n thermal-convection loops'

indicate no seri-

ous problems due t o reactions between t h e salt and t h e proposed reactor containment material, Hastelloy N.

J. W. Koger and A. P. Litman, MSR Program Semiannu. Progr Feb. 28, 1969, Om-4396, p. 246.

. Rep.

The forced-circulation loop described here (MSR-FCL-1) represents a

more sophisticated test of the compatibility of t h e candidate salt and Hastelloy N.

High coolant v e l o c i t i e s were used, and t h e design thermal

gradient was applied t o t h e system.

The results from t h i s test will

assist i n t h e evaluation of t h e corrosion r e s i s t a n c e of the Hastelloy N containment material and t h e mass t r a n s f e r i n t e r a c t i o n s of the containment material and salt.

Detailed metallurgical results w i l l be presented

separately.

DESIGN AND FABRICATION 2.1

Design Criteria

The MSR-FCL-1 t e s t was designed t o evaluate t h e use of sodium fluoro-

borate2 s a l t i n contact with Hastelloy N a l l o y containment material at conditions simulating t h e secondary-coolant (high-temperature side of the

steam generator) c i r c u i t of molten-salt reactors.

One objective of t h e

t e s t was t o develop the technology associated with t h e new salt by using

it i n a r e l a t i v e l y complex operating system. The BFS vapor pressure of t h e sodium fluoroborate salt i s higher

(e.@;., 141 mm Hg a t t h e maximum loop temperature of 1090'F)

than t h e

vapor pressure of other salts developed f o r use i n molten-salt reactors. Accommodating the BF, vapor pressure of t h e salt a t elevated temperature i n MSR-FCL-1 was a major design problem, since BFa i s a noxious gas and'

a design t o provide adequate v e n t i l a t i o n f o r personnel protection was required.

An e x i s t i n g system design3 was used

as a b a s i s f o r MSR-FCL-1.

Cen-

t r i f u g a l pumps, air blowers, e l e c t r i c a l transformers, and miscellaneous control equipment used i n previous corrosion tests of t h i s type were

2Unless otherwise indicated t h e term sodium fluoroborate w i l l be used i n t h i s report t o designate the NaBF4-8 mole 6 NaF e u t e c t i c mixture.

3J. L. Crowley, W. B. McDonald, and D. L. Clark, Design and Operat i o n of Forced-Circulation Testing Loops with Molten S a l t , om-TM-528

h 1963).

3 available.

The reuse of t h e available instrument and control design and

the e x i s t i n g equipment resulted i n a system of limited f l e x i b i l i t y ; however, these design features had been previously tested and funds were only available f o r minimum redesign and fabrication of new equipment. The hydraulic c h a r a c t e r i s t i c s of t h e e x i s t i n g pump were a s p e c i f i c l i m i t ing f a c t o r on loop performance. The f a c i l i t y was o r i g i n a l l y designed t o operate f o r 10,000 h r and t o provide a maximum bulk f l u i d salt temperature of l l P j 째 F , a bulk fluid

AT of 275'F at a velocity of 7 1/4 f p s ( 3 gpm), and a t o t a l heat input of 94 kW. However, the loop was not operated a t these conditions. After the o r i g i n a l design was completed and before t h e loop fabrication was

complete, the t e s t conditions were changed t o more nearly match t h e t e m perature p r o f i l e of the coolant c i r c u i t of the Molten-Salt Reactor Experiment (MSRE), which was then operating.

This modification t o program plans

was a prelude t o t h e proposed introduction of sodium fluoroborate i n t o the secondary-coolant c i r c u i t of the MSRE. , 5

The t e s t f a c i l i t y w a s operated at

a maximum bulk f l u i d temperature of 1090째F, a bulk f l u i d A!T of lb째F a t a velocity of 10 f p s ( 4 gpm) , and a t o t a l heat input of 53 kW. Corrosion specimens were introduced i n t o t h e system a t appropriate locations t o obtain accurate weight change, chemistry change, and m e t a l lographic data.

Periodic removal and r e i n s e r t i o n of the specimens were

specified at approximately 2000-hr i n t e r v a l s .

S a l t sampling a t approxi-

mately 500-hr i n t e r v a l s was specified t o permit chemical analyses necessary f o r characterization of corrosion processes occurring during operation. Protective instrumentation and an a u x i l i a r y power supply were provided i n an a t t e m p t t o prevent accidental. freezing of the salt due t o

loss of normal e l e c t r i c a l supply o r a pump stoppage. Originally t h i s protective system was t o be continuously monitored by f a c i l i t y operators; however, evening and night s h i f t operator coverage was discontinued j

during the l a t t e r p a r t of t h e operating period, and t h e f a c i l i t y had t o be modified f o r unattended operation.

4 2.2

General Design Information

A simplified schematic drawing of t h e test loop i s shown i n Fig. 1, and an isometric drawing of t h e equipment i s shown i n Fig. 2. A complete flowsheet Fs included as Appendix A.

Sodium fluoroborate i s discharged

downward from t h e salt pump (model LIB) a t a temperature of 950'F and at

afl'owrateof

4 gpm.

The salt e n t e r s t h e first of two heat input sections

and i s heated t o lO3O'F;

flows over three Hastelloy N metallurgical speci-

mens; continues through t h e second heat input section, where t h e bulk f l u i d temperature is increased t o 1090'F;

and flows over t h r e e additional

metallurgical specimens before being cooled i n a heat exchanger t o 950'F. The cooled salt then flows

Over

two more metallurgical specimens before

returning t o t h e inlet of t h e pump.

The salt inventory i s s t o r e d i n a sump tank located below t h e primary piping system.

A high-purity helium gas blanket i s maintained above the

salt surfaces i n t h i s tank and i n t h e pump t o minimize salt contamination. A d i p l e g i n t h e sump tank allows t h e l i q u i d salt t o be forced by helium overpressure i n t o t h e c i r c u l a t i n g system.

The sump tank i s designed t o

contain approximately twice the salt volume t o be circulated.

A freeze

valve serves t o i s o l a t e t h e salt i n the c i r c u l a t i n g system from t h e sump' tank inventory.

This valve consists of a cooling a i r l i n e i n s t a l l e d

around t h e 1/4-in.-ODY 0.035-in.-wall t h e c i r c u l a t i n g system.

tubing connecting t h e sump tank t o

Piping of t h e c i r c u l a t i n g system i s p r i n c i p a l l y

1/2-in. -OD by 0.042-in. - w a l l Hastelloy N tubing.

No d i r e c t flow measuring equipment i s provided i n t h e c i r c u l a t i n g -

salt system; provisions are made t o measure t h e flow calorimetrically. Three c a l i b r a t e d Chromel-Alumel thermocouples are i n s t a l l e d at both t h e inlet and exit of one of t h e heater sections. By determining the thermal losses f r o m t h i s section at several temperature l e v e l s with no salt i n the system, it i s possible t o obtain the net e l e c t r i c a l heat input during operation.

Flow rates can then be calculated from the net e l e c t r i c a l

power input and t h e observed temperature rise i n t h e salt as it passed through t h e heater. Engineering parameters of t h e system are shown i n Table 1, and composition and physical properties of sodium fluoroborate are shown i n

Table 2.

ORNL-DWG 68- 279712

SALT SAMPLE

HEATER LUG (TYPICAL)

VELOCITY 40 fps FLOW RATE 4 gpm SUMP

Fig. 1. Simplified schematic of molten-salt corrosion t e s t loop.

ORNL-LR-WVO 64740RA

METALLURGY

DETAIL B

10 kva POWER SUPPLY

FREEZE VALVE

(COOLER PREHEAT)

Fig. 2.

Molten-salt corrosion testing loop and power supplies.

7 Table 1. Selected engineering d a t a f o r MSR-FCL-1 Based on actual operating conditions

Materials, temperatures, and v e l o c i t i e s Tubing and specimens Nominal tubing s i z e Total tubing length Bulk f l u i d temperature (max) Bulk f l u i d temperature (min) B u l k f l u i d A!J! F l o w rate Liquid v e l o c i t y

Standard Hastelloy N 1/2 i n . OD, 0.042 i n . w a l l

57 ft 1090OF 950 OF 140O F

gPm

10 f p s

Cooler heat t r a n s f e r Heat load at finned cooler Liquid Reynolds number Liquid film heat t r a n s f e r c o e f f i c i e n t Length of finned 1/2-in.-OD cooler c o i l Coolant air flow Coolant air AT

180,900 Btu/hr (-53 kW) 45,000 -2000 Btu hrâ&#x20AC;? ft12 ( 26 et 995 :cfi 185â&#x20AC;&#x153;F

Pumping requirements

a t 4 gpm System Required pump speed

57.5 P s i (65 f t > 5000 rpm

S a l t inventory being c i r c u l a t e d

85 in.3

Volume i n pump bowl Volume i n tubing T o t a l volume T o t a l weight

in.3

131 in.3 8.81 l b Miscellaneous

Surface t o volume r a t i o f o r c i r c u l a t i n g salt Volume of dump tank

7 in.Z/in.3 274 in.3

The p o s s i b i l i t y of leskage of BF3 gas through t h e r o t a t i n g mechani-

cal face seal of t h e pump o r from t h e valves and f i t t i n g s i n t h e pump

seal o i l l i n e s exists. To protect personnel from t h i s noxious gas, a v e n t i l a t e d cabinet i s provided t o enclose t h e LFB pump and t h e gas system.

An induced draft blower exhausts t h e air from t h e cabinet through

ducts t o t h e roof of t h e building.

8 !Cable 2.

Composition and physical properties of sodium fluoroborate

Composition (mole $)

NaBF4 NaF

approximate molecular weight

104

Approximate melting point (OF) a Vapor pressurej log,, P (mm Hg) = 9.024

725

A t 1090OF A t 950°F

140

Densityb ( l b / f i 3 ) = 141.4

- 0.0247t

(OF)

114.4

At 1090OF A t 1020°F A t 950°F Viscosity

116.2 11709

)

( l b ft'lhr-'

= 0.2121 exp

4032

TT"R7

A t 1090OF A t 1020OF A t 950°F

Heat capacity

2.86 3.23

3.7 [Btu lb" (')FO

Thermal conductivity

]

[Btu hr" ft-' (

A t 1090"F A t 1020'F A t 950°F

0.360

] 0.23 0.235 0.24

S. Cantor e t al., Physical Properties of Molten-Salt Reactor Fuel, Coolant, and Flush S a l t , ORNL-TM-23l6, p. 33 (August 1960). bS. Cantor, MSR Program Semiannu. Progr. Rep. Aug. 31, 1969, ORNL-4449, pp. 145-47. C

A. S. Dworkin, MSR Program Semiannu. Frogr. Rep. Feb. 29,

1968, 0RM;-4254, p.

168.

dJ. W. Cooke, MSR Program Semiannu. Progr. Rep. Aug. 31, 1969, ORNL-4449, p. 92.

9 I n addition, a sheet-metal enclosure is provided around t h e salt piping and heat exchanger t o protect operating personnel from gross l i q u i d leakage.

The system piping i s considered s u f f i c i e n t l y reliable

t o preclude t h e need f o r s p e c i a l exhaust v e n t i l a t i o n from t h i s enclosure f o r protection against BF,

leakage.

Favorable v e n t i l a t i o n conditions

e x i s t i n t h e t e s t area, which has a 50-ft-high c e i l i n g and continuous exhaust v e n t i l a t i o n . The t e s t loop is shown i n Fig. 3 during i n s t a l l a t i o n of t h e heaters and thermocouples.

Figure 4 shows t h e completed i n s t a l l a t i o n . 2.3

2.3.1

Detailed Design and Fabrication

Heater The heat input i n t o t h e s a l t is accomplished by resistance heating

two sections of t h e system piping, each approximately lo5 i n . long. Voltage i s applied between two lugs attached t o t h e ends of each heatad length of pipe.

Control i s common t o both of t h e heat input sections

(see Fig. 2 ) . 2.3.2

Cooler

Heat i s removed from t h e system by a heat exchanger composed of an air-cooled, 26-ft-l0ng, l9-in.-diam c o i l of 1/2-in.-OD by 0.042-in.-wall tubing t o which 1/16-in.-thick

c i r c u l a r nickel f i n s are attached (see

Fig. 3 ) . These f i n s are brazed t o t h e tubing with Coast Metals 52 furnace braze a l l o y . The finned c o i l i s inside a sheet-metal housing which

serves as t h e cooling a i r duct.

The salt s i d e pressure drop, as limited by t h e capacity of t h e salt pump, prohibits t h e use of a longer heat exchanger c o i l .

Variations i n

f i n diameter and spacing are used t o provide a higher heat flux at th% hot end of t h e cooler.

This geometry creates a f l a t t e n e d salt w a l l t e m -

perature p r o f i l e which makes possible maximum heat removal without cooling t h e w a l l a t t h e cold end of t h e u n i t below t h e 725째F melting point of t h e

salt. [This feature was important during t h e design stages, when t h e expected drop i n t h e bulk f l u i d temperature was from 1125 t o 8 5 0 " ~ . It

Fig. 3. -mocouples

Test loop assembly during i n s t a l l a t i o n of heaters and ther-

12 ’ became less important when the proposed operating conditions were changed t o simulate the Molten-Salt Reactor Experiment coolant c i r c u i t temperature p r o f i l e (lOgW50 OF).

The cooler i s resistance heated during preheating of t h e loop.

This

resistance heat system i s a l s o used t o keep t h e s a l t above t h e melting point during loss of normal building power.

Hastelloy N lugs are i n s t a l l e d

a t t h e i n l e t , midpoint, and e x i t of t h e c o i l f o r attachment of t h r e e e l e c t r i c a l leads.

The lugs project through holes i n the a i r duct t o give

access t o t h e e l e c t r i c a l connections.

During a l o s s of normal power t h e voltage i s supplied t o t h e c e n t r a l lug of t h e c o i l from a diesel-generator u n i t used f o r emergency e l e c t r i c a l supply. A hinged door, provided on t h e air exit side of t h e cooler housing,

i s closed t o reduce t h e heat losses during preheating and i s equipped t o close automatically during a power outage.

The t o p s i d e of t h i s door

and the four sides of the a i r plenum are insulated w i t h Johns Manville

Kaowool thermal insulation t o further reduce t h e heat losses.

This insu-

l a t i o n i s a l s o used t o plug t h e holes where the e l e c t r i c a l lugs penetrate t h e a i r duct. Air t o t h e cooler is supplied through appropriate ducting by a

model 200-A-1 American blower with a 3-hp 1725-rpm motor which provides a maximum air flow of 3200 cf’m a i r through t h e ductwork.

normal operation t h e a i r flow required i s about 1000 cf’m.

However, i n A throttling

damper is provided t o regulate the flow. Selected engineering data on t h e a c t u a l performance of t h e cooler

are sham i n Table 1, along with other engineering parameters of t h e system.

2.393

salt

pump

The salt pump, model LFB, used i n t h i s corrosion t e s t is shown i n Fig. 5 . It i s a centrifugal sump pump designed a t ORNL and features a downward discharge. The pump has an overhung v e r t i c a l shaft, two greasesealed b a l l bearings, and an oil-lubricated mechanical face seal above t h e salt l i q u i d l e v e l and j u s t below t h e lower b a l l bearing.

Shaft and seal cooling are provided by o i l which flows downward through t h e hollow

l i .

ORNL-LR-DWG

IDâ&#x20AC;&#x2DC;S=

9(/2 in Fig. 5 .

Molten-salt pump (model LFB).

30958

14 shaft through a r o t a r y seal.

The o i l leaves through holes i n the shaft

located j u s t above t h e t o p side of t h e mechanical face seal. requires a gas purge as described i n Section 2.3.5.

The pump Pump performance

data taken with water are shown i n Fig. 6.

The model LFB salt pump w a s selected f o r t h i s p a r t i c u l a r test since several pumps were available and over 400,000 cumulative hours of successful operation had been experienced i n many previous applications a t Oak Ridge National Laboratory.

The head capability of t h e pump i s somewhat lower than desired, and t h e acceptance of t h i s l i m i t a t i o n r e s u l t e d i n a maximum l i q u i d v e l o c i t y of 10 f p s . The pump tank contains t h e only f r e e l i q u i d surface i n t h e circul a t i n g system during normal operation with t h e dump tank i s o l a t e d by a freeze valve.

The pump is located a t the highest point i n the flow c i r -

c u i t , and t h e pump tank a c t s as a l i q u i d expansion volume. The l i q u i d level i n t h e tank is indicated by two spark plug probes which have Hastelloy N extensions welded t o t h e center electrodes t o make contact with t h e l i q u i d salt at preset elevations.

A salt sampling apparatus i s provided a t the pump tank, as described i n Section 2.3.4.

2.3.4

S a l t sampler A cross section of t h e molten-salt sampler is shown i n Fig. 7.

i s used t o remove salt samples from the pump tank a t approximately 500h r i n t e r v a l s during t h e t e s t program.

interrupted during sampling.)

(The t e s t loop operation i s not

The sampler c o n s i s t s of a d i p tube with a

small copper bucket attached on t h e lower end which i s lowered i n t o t h e molten salt i n t h e pump tank.

Vacuum and inert-gas b a c k - f i l l i n g con-

nections are provided so that the sampler assembly can be attached t o or removed from the pump tank without contaminating t h e salt inventory. A Swagelok f i t t i n g with Teflon ferrules a c t s as the packing gland on the

l/b-in.-OD

d i p tube.

The Swagelok nut i s loosened, as required, t o per-

m i t r a i s i n g or lowering of the dip tube.

The o r i g i n a l bucket design had

a capacity of about 2 g of sodium fluoroborate.

A second separate com-

partment which holds about 0.5 g was added later t o provide a separate sample f o r an oxygen analysis.

ORNL-LR-WdG 65065A

If0 100

90 80

) .

w I

50 40

30 20 10

Fig.

4 5 FLOW (gpm)

Performance c h a r a c t e r i s t i c s of t h e LFB s a l t pump i n w a t e r .

ORNL-DWG 68-2796R

SAMPLE REMOVAL SECTION

E I

c PERMANENT LOOP ASSEMBLY

BALL VALVE

/LFB

PUMP

MAXIMUM Liauio LEVEL

___. ____

MINIMUM LlPUlD LEVEL

Fig. 7. Cross section of a molten-salt sampling device.

l i

2.3.5

BFS system A r e l a t i v e l y complex tubing system i s provided t o supply He-BF,

mixtures f o r use i n purging s h a f t seal o i l leakage from t h e s a l t pump. r

A simplified schematic of t h e system i s shown i n Fig. 8, and t h e com-

p l e t e system i s shown i n t h e flowsheet of Appendix A.

Special pressure regulators from Matheson Company with chemically coated nickel bodies

and Monel diaphragms a r e used on gas cylinders containing BF,.

These

materials are used t o r e s i s t a t t a c k by HF i n case of moisture contami-

nation of t h e BFs gas.

A l l gaskets, valve packings, or soft valve seats

were of Teflon o r Kel-F, which a r e a l s o r e s i s t a n t t o a t t a c k by HF. A standard 200-ft3 capacity gas cylinder supplies a gas flow of about 80 cc/min t o t h e reference s i d e of a thermal conductivity c e l l ; t h e gas flow then continues on t o t h e pump.

The gas flow t o t h e pump i s used

t o purge seal o i l leakage from a catch basin and carry it t o an o i l t r a p , from which t h e o i l can be drained manually as required.

The gas

flow then returns t o t h e thermal conductivity c e l l , where a comparative i

measurement i s made t o detect any change of BF3 concentration i n t h e helium.

It was o r i g i n a l l y thought t h a t a 3% mixture of BF3 and helium ( f o r a 950째F pump bowl temperature) would be necessary f o r t h e purge flow

through t h e seal o i l leakage catch basin of the s a l t pump.

This require-

ment was brought about by t h e f a c t t h a t the s e a l o i l leakage catch basin and t h e gas space above t h e salt l e v e l i n t h e pump a r e interconnected, and thus a possible path f o r l o s s of BF, from t h e salt is created.

The

use of a purge-gas mixture having t h e same composition as t h e gas i n t h e pump bowl would preclude removal of BF3 and a r e s u l t a n t change i n

salt composition.

However, it was found i n a c t u a l operation, as discussed

i n Section 3.2, t h a t t h e use of He-BF3 mixture w a s unnecessary.

Since

t h e loss of BFs from t h e pump i n a pure helium purge w a s t o o low t o j u s t i f y t h e complications attending BF3 addition, a pure helium purge was used throughout most of t h e t e s t . Most of t h e seal purge system i s fabricated of l/lc-in.-OD by 0.035-in.-wal.l sively.

copper tubing.

Brass compression f i t t i n g s a r e used exten-

Check valves are used t o preclude BFs backflow i n t o helium supply

l i n e s o r backflow of atmospheric moisture i n t o t h e BF3-He vent l i n e s .

ORNL-DWG 68-2795

FLOW INDICATOR

THROTTLE VALVE

CONDENSER OIL TRAP

SEAL PURGE

CONDUCTIVITY CELL

FLOW INDICATOR THROTTLE VALVE PRESSURE GAGE

PRESSURE REGULATOR

HELIUM-BFS MIXTURE SUPPLY

Fig. 8. Molten-salt forced-circulation corrosion loop schematic LFB pump seal purge system.

- simplified

2.3.6

Fill and drain tank

The f i l l and drain tank i s fabricated from a 23 3/16-in. length of Hastelloy N, 5-in., sched-40 pipe with 1/2-in.-thick f l a t heads. The f i v e pipe risers located on t h e c y l i n d r i c a l surface of t h e tank provide f o r salt addition and removal, spark plug l e v e l indication, and gas pressurization.

A drain l i n e i s provided a t t h e bottom of the tank as

an additional path f o r s a l t removal.

The tank i s e l e c t r i c a l l y insulated

from ground t o prevent t h e flow of e l e c t r i c a l current from t h e main loop tubing, which i s resistance heated during c e r t a i n periods of off-normal operation.

2.3.7 Corrosion specimen design Corrosion specimens (see Fig. 1) are used t o monitor corrosion rates a t t h e points of maximum, minimum, and intermediate bulk f l u i d tempera-

tures.

The Hastelloy N specimens are approximately 2 5/8 i n . long,

0.250 i n . wide, and 0.030 i n . t h i c k .

A t o t a l of eight specimens are

Details of t h e corrosion specimens design and mounting arrangement are shown i n Fig. 9. The specimens a r e

mounted i n t h e t h r e e locations.

mounted on t h e Hastelloy N s t r i n g e r s , i n s e r t e d i n t o t h e 1/2-in. tubing, and tack welded i n t o position. The section of 1/2-in. tubing containing the specimens i s then b u t t welded i n t o t h e system piping.

2.3.8

E l e c t r i c a l system The e l e c t r i c a l power system i s shown schematically i n Fig. 10.

Power i s supplied t o t h e t e s t f a c i l i t y from a 460-V, three-phase, d e l t a connected building supply. A separate connection from a diesel-generator provides emergency power t o some of t h e equipment i n t h e event of a failure t o t h e normal building supply.

Upon failure of t h e normal supply voltage, t h e diesel-generator i s i

automatically s t a r t e d , and an automatic t r a n s f e r switch connects t h e emergency power supply t o t h e f a c i l i t y . When normal power becomes a v a i l able, the automatic switch returns t h e system load t o t h i s supply.

The heat input f o r normal operation i s provided by two resistance-

heated sections.

Voltage i s supplied t o these sections through a

ORNL-DWG 60-4294R

, CORROSION INSERT TAB AND THEN

Fig. 9.

Mol-ten-salt t e s t loop corrosion specimens.

ORNL-DWG 72-9802

DIESEL GENERATOR

13.8 kV/460 V 1000kVA

39 TRANSFORMER

> 1

DISCONNECT SWITCH

1 NORMAL POWER BUS

EMERGENCY POWER BUS

1 r-----

it?

((0kVA SATURABLE REACTOR 110 kVA 4 20/40-?6V 1600A AUTOMATIC OPERATED CIRCUIT

MAIN LOOP HEATER

BREAKER

LIGHTING AND MISCELLANEOUS

INSTRUMENT POWER

Fig. 10.

I AUXILIARY HEATERS

5 hP PUMP MOTOR

3 hp LUBRICATION 3 hP COOLER EXHAUST PUMP BLOWER BLOWER MOTOR MOTOR

Schematic o f e l e c t r i c a l power system.

22 saturable reactor, which i n t u r n supplies a 110-kVA high-current t r a n s former.

Temperature i s controlled on these sections by a v a r i a t i o n i n

t h e impedance of t h e saturable reactor. During normal operation t h e c i r c u i t breaker, shown i n Fig. 2, i s closed and t h e e l e c t r i c a l p o t e n t i a l i s applied between t h e two sets of

lugs ( A D , C&D).

This c i r c u i t breaker i s opened manually t o permit pre-

heating of t h e piping system (except cooler) and i s automatically opened t o provide heat t o all t h e system piping (except cooler) under emergency conditions.

When t h e c i r c u i t breaker is open, t h e e l e c t r i c a l p o t e n t i a l

i s applied between lugs A and C, and t h e r e s u l t i n g two p a r a l l e l e l e c t r i c a l resistance heating c i r c u i t s keep t h e system temperature above t h e freezing point of t h e s a l t .

Power measuring instrumentation i s provided

t o determine t h e heat input t o t h e system. A separately controlled resistance-heated c i r c u i t i s provided f o r preheating t h e cooler.

When normal power is l o s t , automatic controls

d s o apply e l e c t r i c p o t e n t i a l t o t h i s section of piping t o prevent freez-

ing of t h e salt. Additional e l e c t r i c supply sources are provided f o r t h e salt pump motor, lube o i l pumps, t h e cooler blower motor, t h e BF3 cubicle exhaust blower, instrument power, and miscellaneous l i g h t i n g and auxiliaries.

2.3.9

Instrumentation and control The salt pump i s driven by a 5-hp 440-V motor connected t o a

variable-speed magnetic clutch. t o t h e pump by V-belts.

The clutch output torque i s delivered

The speed of t h e coupled u n i t s i s regulated by

varying t h e supply voltage t o t h e magnetic coupling.

The normal supply

i s from an e l e c t r o n i c u n i t furnished with t h e magnetic clutch.

In the

event of t h e l o s s of t h e normal clutch control voltage, t h e loop i s automatically placed i n a standby (preheat) condition. Pump speed i s measured by a tachometer b u i l t i n t o t h e magnetic clutch, and alarms are provided f o r low and high speed.

The pump speed T

is checked with a "Strobe" l i g h t a t t h e beginning of each t e s t run t o insure t h a t the desired speed i s obtained. The loop temperatures are controlled by a k e d s and Northrup "Speedomax-H" controller, which senses changes i n loop temperature and

- *

I W 5

transmits a signal t o t h e saturable reactor t o increase or decrease voltage applied t o t h e two resistance-heated sections of t h e piping. Controls are a l s o provided t o close t h e o u t l e t damper on t h e radiator

air duct, stop t h e blower motor and t h e salt pump, and t r a n s f e r the main heat input t o t h e preheat mode i n t h e event of any of the following offnormal conditions : 1. low clutch speed, 2. salt high temperature,

3. salt low temperature, 4. loss of normal power t o the f a c i l i t y , 5 . low lube o i l flow t o the salt pump. Bypass switches are provided around most of these instruments t o f a c i l i -

tate s t a r t u p and t o provide a means of t e s t i n g t h e workability of the control system during normal operation. 2.4

Quality Assurance

Although t h e design of t h e salt circulating system was e s s e n t i a l l y t h e same as had been used on a previous program, it w a s reviewed by t h e ORNL Pressure Vessel Review Committee.

Complete h i s t o r i e s of t h e Hastelloy N used i n the pressure-containing portion of t h e loop were documented, except f o r t h e salt pump, which had been fabricated and assembled i n accordance with ORNL Reactor Division Standard ProCedWes i n force at the time. Although records of the mate-

rials o r welding were not available, t h e administrative procedures i n effect a t t h e t i m e of fabrication provided assurance of t h e i n t e g r i t y of t h e pump.

Since many of these pumps had been operated and hundreds of

thousands of hours of experience with t h i s type of equipment had been accumulated, it was f e l t that t h e r e l i a b i l i t y of t h e u n i t s was s u f f i c i e n t l y established t o warrant t h e i r use without complete documentation. !The inspection of t h e materials used t o fabricate the salt-containing

portions of the system other than the pump included ultrasonic tests and dye-penetrant checks i n accordance with ORNL Metals and Ceramics Division

specifications MET-NDT 1 through 4.

24 Welding of components and assembly i n t o the system were conducted

i n accordance with Metals and Ceramics Division specification PS-23, -25, and -35, which include welder qualification procedures, weld j o i n t design, and welding parameter limitations. ‘Welds were inspected by xray examination and dye-penetrant methods stated i n Metals and Ceramics Division specification MET-WR 200 and 201.

Material and cleaning requirements invoked during fabrication included degreasing with perchloroethylene vapor, followed by water and alcohol rinses.

Before each part was welded i n t o t h e system, it was

again wiped with an alcohol-soaked cloth.

Both t h e p a r t and t h e cleaning

cloth were visually examined f o r evidence of foreign k t e r i a l . Au. cleanliness, material, and weld inspections were made by person-

nel other than those having the responsibility f o r fabrication and assemb l y . Weld reports, which included t h e inspections and materials c e r t i f i cations, are on f i l e with the Inspection Engineering Department.

H e l i u m leak tests were made on t h e completed piping assembly p r i o r

t o i n s t a l l a t i o n of t h e pump rotary assenibly i n t o t h e pump bowl.

Leak t e s t i n g was done i n accordance with ORNL Inspection Engineering Quality Assurance Procedure 7. No detectable leaks were observed. All wiring was given a terminal-to-terminal check p r i o r t o energizing.

Each control function was checked manually t o insure t h a t t h e protective schemes were operating properly p r i o r t o f i l l i n g of t h e system. Operational procedures, including abnormal condition procedures,

were prepared t o assist t h e operators. A complete description of the operation of the control system was prepared (see Appendix B), and t r a i n ing sessions were conducted f o r t h e personnel.

OPERATING EXPERIENCE

The test loop has been operated f o r 10,335 hr a t design conditions f o r an additional 1135 h r a t off-design temperature.

A chart of t h e

operating history i s shown i n Fig. 11. For most of t h i s t i m e t h e system

was operated a t 10gO°F maximum bulk fluid temperature and 950°F minimum bulk f l u i d temperature.

t h e system. calculation.

Figure 12 i s a t y p i c a l temperature p r o f i l e of

The inner w a l l temperatures are estimated from heat t r a n s f e r

ORNL-DWG 69-2535

TO PUMP

LENGTH (ft)

Fig. 12. Temperature p r o f i l e of molten-salt forced-circulation corrosion loop, MSR-FCL-1, at t y p i c a l operating conditions.

jh, I

After r a i s i n g the sodium fluoroborate from the sump tank i n t o the s a l t piping proper and establishing t h e freeze valve, the system i s

started.

The salt pump i s started and the speed i s adjusted t o approxi-

mately 5000 rpm.

The main power i s t r a n s f e r r e d t o the two resistance-

heated piping sections by closing the c i r c u i t breaker, and the loop t e m perature i s increased by adjusting t h e temperature c o n t r o l l e r .

The sys-

t e m d i f f e r e n t i a l temperature i s established by s t a r t i n g the blower and adjusting t h e damper i n t h e air system duct. For t h e i n i t i a l s t a r t u p a flushing charge of salt was run i n the salt piping f o r 478 h r , after which it was discarded and t h e working charge of salt was i n s t a l l e d . The r e l i a b i l i t y of t h e system during t h e i n i t i a l 10,000 h r of op-

e r a t i o n was very good, but after t h i s t h e several d i f f i c u l t i e s were encountered.

A pump bearing failure occurred, r e s u l t i n g i n damage t o

the pump impeller.

t h e salt piping.

Chips were rubbed from t h e impeller and deposited i n Extensive r e p a i r s t o remove these chips f r o m t h e loop

piping were necessary.

I n addition, fatigue failure of an o i l l i n e

r e s u l t e d i n an o i l fire, requiring extensive r e p a i r s .

Subsequently, t h e

loop piping was ruptured during an inadvertent overheating t r a n s i e n t caused by a defective control thermocouple and an operator e r r o r during the replacement of t h e thermocouple.

Table 3 l i s t s t h e interruptions

t h a t occurred during the operation period, over h a l f of which (15) were

due t o problems with component auxiliaries such as t h e pump r o t a r y o i l seal and drive motor and t h e blower s h a f t bearings. Replacement bearings

i n t h e blower and blower drive motor were required about every six months. I

3 . 1 Heat Transfer Performance of Sodium Fluoroborate - Since no published heat t r a n s f e r data were available f o r the sodium fluoroborate salt, t h e heat t r a n s f e r c h a r a c t e r i s t i c s of sodium fluoroborate

were measured i n t h e MSR-FCL-1. Provisions f o r these heat t r a n s f e r measurements were not p a r t of t h e o r i g i n a l design c r i t e r i a , and t h e tests

were made with e x i s t i n g instrumentation which was not highly sophisticated. Also considerable uncertainty existed i n available physical property data, p a r t i c u l a r l y on v i s c o s i t y and thermal conductivity; so t h e absolute accuracy of results obtained i s questionable.

28 Table 3.

MSR-FCL-1 operational interruptions Number of

Item

failures ~

Rotary o i l seal (Deublin) leakage

5 3 6

S a l t pump bearing failures Drive motor and clutch problems Air blower .bearings

6 4

Instrument malfunctions E l e c t r i c a l system d i f f i c u l t i e s O i l l i n e fatigue failure a t pump rotary seal

Other mechanical problems

1 2

Total

The heat t r a n s f e r data were obtained i n one of t h e resistance-heated; sections of t h e loop piping.

This section w a s lo5 i n . i n length and

0.410 i n . i n inside diameter.

The tubing inside diameter was determined

by micrometers, and w a l l thickness measurements were made with a model 14 Bronson Vidi-gage.

The flow rate through t h e tubing was measured calori-

metrically by observing the power input and t h e temperature rise of t h e Heat losses at various temperature l e v e l s had been determined pre-

salt.

viously.

The specific heat data f o r the salt presented i n Table 2 was

among t h e better defined physical property data and had an uncertainty of +2$. The f l o w velocity was calculated using salt density data with an uncertainty of 546. Power input measurements were made with instruments of +0.5$ accuracy. The temperature measurements were made with 1/16-in. -OD stainless-

steel-sheathed, insulated-junction,

Chromel-Alumel thermocouples.

Bulk

f l u i d temperatures a t t h e heater inlet and. exit were each measured by

three calibrated thermocouples.

Ten thermocouples located along t h e

105-111. length were used t o obtain the w a l l temperature i n the heated region.

29 A l l thermocouples were e l e c t r i c a l l y i n s u l a t d from t h e tubing w a l l

t o preclude an e l e c t r i c a l path along t h e s t a i n l e s s steel sheaths, since

a l l portions of t h e piping were above ground p o t e n t i a l during resistance heating. Two l a y e r s of quartz tape provided e l e c t r i c a l i s o l a t i o n from t h e piping and a l s o served t o thermally i n s u l a t e t h e thermocouples from t h e pipe w a l l .

The ends of t h e thermocouples Mere i n s t a l l e d i n a 180"

a r c around t h e quastz-tape-covered tube and heild i n place with a band of shimstock spot welded t o i t s e l f .

Two inches af "Hi-Temp" diatomaceous

earth formed t h e thermal insulation f o r t h e piping.

The detail on ther-

mocouple i n s t a l l a t i o n i s presented t o emphasize t h a t t h e configuration

was not i d e a l f o r accurate temperature measurement. The e r r o r between insulated thermocouples and thermocouples i n s t a l l e d d i r e c t l y on t h e pipe w a l l was l a t e r determined t o be less than 10째F.

The overall AT from

pipe w a l l t o bulk f l u i d ranged up t o 100째F, s o t h e thermocouple e r r o r of 10"F represents about a lo$ uncertainty.

Erformance data were obtained a t heater i n l e t temperatures from

974 t o 1 0 6 0 ' ~and heater exittemperaturesfrom 1038 t o 1170째F. The Reynolds modulus ranged from 5500 t o 51,400, and heat fluxes ranges from 15,750 t o 160,000 Btu hr-1ft'-2.

The measured heat t r a n s f e r coefficients

ranged from 267 t o 2130 Btu hr-l f't-2 ( OF)-'

The data obtained correlat2d

w e l l w i t h t h e Dittus-Boelter equation as shown i n Fig. 13 (using recently determined physical property values from Table 2 ) .

Although no s t a t i s t i -

c a l analysis has been made, it i s estimated t h a t t h e e r r o r i n t h e measurements is less t h a n 2 6 .

These heat t r a n s f e r data c o n s t i t u t e d t h e

f i r s t demonstration t h a t sodium fluoroborate performs as an ordinary heat t r a n s f e r fluid. 3.2

BF3 Handling

The LFB s a l t pump was designed t o op5rate with approximately 80 cc/ min of helium purge through t h e pump s h a f t seal region t o remove t r a c e s of o i l leaking through t h e r o t a t i n g face seal (see Fig. 5 ) .

The vapor

pressure of t h e NaBF4 component of t h e s a l t mixture, as shown i n Fig. 14, produces a BF3 p a r t i a l pressure above t h e salt level i n t h e pump bowl. Since t h e helium purge tends t o carry some of t h e BF3 out of t h e system,

ORNL-DWG 6843483R

!03

102

to'

io3

io4

lo5

REYNOLDS NUMBER

Fig. 13. Beat t r a n s f e r c h a r a c t e r i s t i c s of NaBF4-NaF (92-8 mole flowing i n 0.410-in. -ID tube.

Fig. 14. Vapor pressure of NaBFQ-NaF (92-8 mole % TM-2316. )

(From ORNL-

it i s possible t o change t h e salt composition by gradual depletion of the v o l a t i l e constituent.

As indicated by the NaBF4-NaF phase diagram (Fig. l5), t h e freezing point of t h e salt mixture changes d r a s t i c a l l y

with a change i n composition near the eutectic.

Therefore t h i s problem

needed further consideration. The helium purge, as originally i n s t a l l e d , w a s through t h e seal region of t h e pump, which was loosely coupled through an annulus around the pump shaft t o the helium gas space above t h e salt l e v e l i n t h e pump bowl.

It was assumed t h a t BF3 vapors from t h e salt m i x t u r e would diffuse

up the shaft annulus i n t o t h e s e a l region and be c a r r i e d away by t h e purge

To avoid t h e problem of BF3 depletion i n t h e salt mixture, a system was i n s t a l l e d t o permit blending BF3 i n t o t h e helium purge t o produce a gas.

BF3 concentration i n t h e purge gas equivalent t o t h e concentration i n t h e

pump bowl. Thus, no net l o s s of BF3 i n t h e system would occur. The p o s s i b i l i t y of chemical interaction of the BFs i n the purge gas with the o i l i n t h e seal region a l s o had t o be considered, and preliminary tests were run t o see i f a problem existed.

The amount of BFa i n helium

required t o sustain the 9 2 4 s a l t mixture was calculated t o be l$, with

a pump bowl temperature of 8 5 0 " ~ ,or 3%with t h e pump a t 950째F.

Mixtures of these two gases were prepared by adding t h e proper amount of BF3 t o b o t t l e s containing helium; however, confirmatory analyses f o r the concent r a t i o n of BFa i n helium were unsuccessful.

Checks with commercial sup-

p l i e r s of mixed gases revealed t h a t there were no economical methods f o r determining t h e BF,

concentrations i n helium i n t h e 1 t o 3% range.

The

BF3 gas adsorbs on t h e walls of analytical equipment, r e s u l t i n g i n gross

inaccuracies i n analytical results.

Attempts a t confirmatory analysis were abandoned, and t h e concentrations were assumed t o be those predicted by t h e mixing calculations based on volume, temperatures, and pressures.

Tests were conducted t o examine t h e e f f e c t of mixtures of 1 and 3% BF3 i n helium of t h e Gulfspin

35 pump o i l under conditions which would

simulate i t s use i n t h e pump s e a l - o i l purge system. The r e s u l t s f o r t h e 18 BF:, mixture indicated t h a t the seal leakage o i l would not be affected deleteriously by contact with t h e mixture.

Some discoloration and an increase i n a c i d i t y were noted i n t h e o i l after only a f e w hours of

exposure t o t h e gas mixture; however, viscosity changes over a long

ORNL-MNG 67- 94234,

-Y W

700

400

300 200 NaF

Fig. 15.

40 60 NaBF4 (mole % 1

The system NaF-NaBF4.

Na8F4

34 period gave no reason t o suspect that t h e g m a l l passages of t h e pump seal purge system would become plugged with degraded o i l . Results of two separate room-temperature tests of approximately one

week's duration using the 3s BF3 m i x t u r e with a n o i l leakage flow rate of 10 cc/day and a gas flow rate of

80 cc/min indicated that the seal o i l

purge l i n e would probably become plugged during loop operation; thus use of t h i s 376 mixture f o r purging was abandoned.

A black sludge, formed i n

the test setup which simulated t h e pump catch basin, eventually plugged

a 1/8-in.-diam

port (see Fig. 16).

I n these tests t h e o i l removed from

t h e t e s t apparatus was extremely acidic, with a pH from 1.0 t o 1.5. Attempts t o determine the composition of t h e o i l sludge were unsuccessful.

Infrared spectrophotometric examination indicated that t r a c e s

of water were probably removed from the piping system by t h e sparging gas and t h a t the acid formed by the BF3-water reaction had attacked one or more of the ingredients of t h e o i l t o form t h e sludge.

The BF3 a l s o

produced, e i t h e r as products of degradation or by d i r e c t addition t o some component o r components, new materials not found i n unexposed o i l .

further e f f o r t was made t o characterize t h e degraded o i l .

To eliminate BF3 i n the seal purge stream and t h e resulting o i l degradation, the purge route through the pump bowl was changed t o provide a pure helium purge gas flow down the pump shaf't.

It was thought t h a t by

providing t h i s purge, helium could be used t o remove t h e leakage o i l from t h e o i l catch basin i n the pump and t h e helium flow down t h e shaft would

deter (except f o r back diffusion) t h e BF3 vapor from reaching t h e o i l . This purge path required t h e addition of a new o u t l e t gas l i n e from the

pump bowl and a new l i n e f o r BF3 addition i n t o the pump bowl.

The BF3

addition was required since the helium flow down t h e shaft and across t h e BF3 vapor space i n t h e pump would carry off BF3 vapors i n even greater quantities than had been anticipated with t h e purge only through the face

seal region.

After one day of operation t h e o u t l e t l i n e from the pump

vapor space plugged with reaction products from the salt, o i l , and BF3. As'an expedient, a decision was made t o return t o t h e o r i g i n a l design f o r purging t h e pump seal with no BF3 addition t o t h e purge stream.

The

helium was connected t o t h e pump s e a l purge l i n e , and t h e effluent was carefully monitored f o r BF3 contamination.

Measurements from t h e thermal

PHOTO 75900

4 INCHES

Fig. 16. Sludge formation from polymerization of Gulfsyin 35 oil after one week's exposure of 3% BF3-e mixture at room temperature.

36 conductivity c e l l indicated t h a t t h e helium gas (80 c$/min)

leaving t h e

pump o i l catch basin was contaminated with approximately 0.0%

BF,

This

indicated t h a t t h e amount of BF, removed from t h e NaBFB salt during t h e scheduled 10,000-hr operation would not s i g n i f i c a n t l y a l t e r t h e salt composition.

Had t h e BF, depletion been s i g n i f i c a n t l y high, plans were t o

replenish the BF, by i n t e r m i t t e n t gas additions t o the salt. During c a l i b r a t i o n of a thermal conductivity c e l l which was t o be used t o measure t h e concentration of BF, i n t h e e f f l u e n t l i n e from t h e s e a l purge l i n e , a l/bin.-OD copper tubing vent l i n e plugged.

A 3%

mixture of BF, i n helium had been purged through t h e conductivity c e l l and vented t o atmosphere i n a v e n t i l a t i o n system.

Reaction products of

moist air and BF3 completely sealed t h e end of t h e tube and stopped t h e

seal purge (see Fig. 17).

An a c i d i c solution was found i n t h e v e r t i c a l

l i n e M e d i a t e l y adJacent t o t h e discharge end of t h e tube, evidently formed when t h e BFs gas came i n contact with moisture i n the a i r .

Acid

was also formed on t h e v e n t i l a t i o n hood i n t h e v i c i n i t y of the BF3-He vent. Enough a c i d was present t o form droplets on t h e lower edge of t h e hood, which demonstrated t h a t a s u i t a b l e BFa "scrubber" i s required f o r future systems where long-term, reliable venting of s i g n i f i c a n t BF3 concentrations must be maintained. The low BFa concentration i n t h e helium purge from t h e f i n a l con-

figuration of the s h a f t seal purge system r e s u l t e d i n l i t t l e a c i d accumulation a t the gas purge l i n e o u t l e t .

Inversion of t h e purge l i n e out-

l e t port and t h e addition of a bucket-type catch basin helped t o reduce t h e plugging problem a t t h e end of t h e purge l i n e .

No accumulation of

acid on t h e a i r exhaust ducts was v i s i b l e , but a c i d reaction products

were noted a t t h e end of t h e purge l i n e .

As t h e buildup of these products was noted, t h e open end of t h e copper tubing was e i t h e r c l e k e d o r cut o f f .

3.3 S a l t Pump Operation The major problems t o be resolved by t h e use of t h e model LFB pump i n t h i s t e s t program involved (1)t h e e f f e c t of t h e BFa p a r t i a l pressure on t h e o i l i n t h e seal leakage catch basin and (2) t h e bearing and o i l

seal performance at 5000 rpm f o r sustained periods of operation.

The

. h

Fig. 47. Typical plugging formation where BF+e t o atmosphere.

mixtures are vented

38 problems r e l a t i n g t o BF3 reactions with t h e Gulfspin 35 o i l i n t h e pump a r e described i n Section 3.2.

I n addition t h e bearing and seal lifetime

was a point of concern since a pump of t h i s type had not been used i n

applications requiring thousands of hours of operation a t t h e r e l a t i v e l y high speed of 5000 rpm.

A series of i d e n t i c a l pumps had been operated

at speeds around 3000 rpm and had demonstrated adequate r e l i a b i l i t y during about 450,000 h r of ~ p e r a t i o n . ~ Normal operation conditions f o r t h e pump were as follows: S a l t i n l e t temperature, OF

950

S a l t flow rate, gpm

Pump speed, rpm

5000

Coolant o i l

Gulfspin-35

Coolant o i l temperature, "F

110

Pump tank pressure, psig Pump tank cover gas

7.0 Helium

Purge gas f o r s e a l leakage

Helium

Purge gas flow rate, cc/min

The pump was removed f o r routine maintenance a t approximately 2000h r i n t e r v a l s t o i n s t a l l new bearings.

These bearings have a r e l a t i v e l y

short l i f e t i m e expectancy of about 4000 h r a t 5000 rpm.

Normally t h i s

maintenance period coincided with removal of t h e corrosion specimens from t h e loop piping.

However, three bearing f a i l u r e s occurred during opera-

t i o n despite t h e bearing replacement schedule. The polymerization of o i l i n t h e catch basin by reaction with BFa

was no problem during t h e 2000-hr operating periods. The leaking seal o i l was darkened by contact with t h e BF3 and a black coating formed on the bottom of t h e catch basin, but no s i g n i f i c a n t plugging occurred.

This could be a problem, however, i n a system where periodic removal and cleaning are not possible or perhaps where higher BF3 concentrations are present.

The seal o i l catch basin a t t h e conclusion of a t y p i c a l 2000-hr

run i s shown i n Fig. 18.

'J. L. Crowley, W. B. McDonald, and D. L. Clark, Design and Operation of Forced-Circulation Testing Loops with Molten S a l t , ORNL-TM-528, p. 9 7MaY 1963).

Fig. 18. Typical appearance of t h e seal o i l catch basin of t h e s a l t pump after 2000 h r operation (model LFB pump).

40 The seal o i l leakage rate has averaged approximately 1 cc/day (see Table 4).

1.i

The leakage rates were higher than average during short periods

near the end of t h e t e s t , f o r reasons t h a t were not discernible.

. Table 4.

Date leakage was removed

12-9-68 12-18-68 2-14-69 3-25 -69

7-22-69 10-22 -69 12-17-69 1-29-70 4-24-70 10-16 -70 10-19-70 1-11 -71 1-12-71;

Seal o i l leakage rates i n salt pump

Approximat e days of operat ion

Leakage ratea

13 9 58 39 104 80

3.5

38 43 66 51 3 4 1

(C C / b Y )

2.2

0.34 0.51

0.17 0.27 1.05

0.81 0.58 0 .go 20.0

24.0 30.0

aAverage leak rate = 1 cc/day. The s e a l leakage o i l is highly acidic due t o i t s contact with BF,;

tests with litmus paper showed a pH of 1 t o 1.5. Analytical results of o i l samples revealed small amounts of dissolved boron. The mechanical face seal appeared i n good condition upon disassembly a t t h e end of each operating period.

Although there were no indications

of impending trouble, t h e seal was changed as a precautionary measure during each pump maintenance cycle.

The upper bearing normally showed

evidence of l o s s of most of i t s i n t e r n a l lubricant (grease); t h e lower

41 bearing usually appeared i n excellent condition, but both bearings were replaced routinely.

The upper bearing i s affected by t h e drive b e l t

tension and operates under a heavier radial load then the lower bearing. The condition of t h e upper bearing was ample evidence t h a t when t h e salt pump i s b e l t driven, operation a t 5000 rpm f o r 2000-hr periods w a s a

maximum p r a c t i c a l service l i m i t . The sodium fluoroborate drained e a s i l y from t h e rather complex ge-

ometry of t h e s a l t pump.

Normal draining procedure consisted i n circu-

l a t i n g t h e salt a t 1000째F and turning t h e pump a t about 1000 rpm as t h e l i q u i d l e v e l was lowered.

Typical appearance of t h e salt-wetted portions

of t h e pump after a 2000-hr test period i s shown i n Figs. 19 and 20. The w h i t e deposits a r e t r a c e s of frozen sodium fluoroborate salt.

3.4 Corrosion Specimen Removal Corrosion specimens are normally removed f o r examination a t approximately 2000-hr i n t e r v a l s , but when operating problems were encountered they

Were

removed more frequently.

1 ' Fne salt inventory w a s drained i n t o

t h e sump tank, and t h e piping was cooled t o room temperature p r i o r t o specimen removal.

An argon purge flow w a s maintained through t h e loop during specimen removal t o minimize a i r contamination of t h e inner surfaces of the remaining piping. Tubing c u t t e r s were used t o remove the tubing t h a t contained t h e specimens.

Immediately after t h e specimens

were removed, t h e open ends of the piping -rere sealed t o a l l o w s l i g h t

argon pressurization of t h e system w h i l e t h e specimens were cleaned and inspected. The specimen s t r i n g e r s were r e t r i e v e d from t h e tubing after grinding

t h e t a c k weld which joined them t o t h e inner tubing surface.

The grinding was done c a r e f u l l y s o t h a t t h e specimens could be r e i n s t a l l e d i n the same

tubing from which they were recovered.

The specimens were cleaned of residual salt droplets by placing them i n warm d i s t i l l e d water f o r about 1 h r followed by e t h y l alcohol washings and air drying.

were then measured and weight changes calculated.

Specimen weights

Fig. 19. Appearance of t h e s a l t pump bowl after d r a i n i n g s a l t at 1000째F a t conclusion of 2000-hr run (model LFB pump).

PHOTO 9631tA

Fig. 20.

Typical s a l t deposits remaining on support s t r u c t u r e and

heat baffles of LFB pump after draining s a l t a t 1000째F a t conclusion of

2000-hr run.

44 3.5 S a l t Sampling S a l t samples were taken a t t h e start of t h e t e s t and a t about 500-hr intervals thereafter.

The salt was analyzed p r i o r t o operation i n MSR-

FCL-1 (Table 5); t h e o r i g i n a l salt charge contained high concentrations of metallic impurities (Fe, N i , C r , Mo).

The changes i n concentration

of these impurities have been r a t h e r e r r a t i c with t i m e , probably due t o inadvertent moisture contamination of t h e salt inventory.

Some general

trends were observed i n t h e salt analyses a f t e r several thousand hours of operation.

For example, t h e chromium concentration increased from

66 t o -250 ppm and t h e r e a f t e r remained at t h a t general l e v e l , t h e i r o n concentration dropped from 407 ppm and remained a t about 70 ppm, and t h e nickel and molybdenum concentrations were reduced t o less than 10 ppm.

Table 5. Analysis of sodium fluoroborate salt p r i o r t o operation i n MSR-FCL-1 ~~~

21.8%

9 .14% 67.9% 66 PPm 407 PPm 53 PPm 41 PPm

F Cr

Fe Ni Mo

Hao

-400 ppma

-400 ppm

aAnalysis questionable. A cross-sectional view of t h e salt sampler i s shown i n Fig.

7. A

copper bucket i s attached t o t h e lower end of t h e sampler assembly, and t h e assembly is then attached t o a hydrogen furnace s o the bucket i s i n t h e heated zone, and t h e bucket i s f i r e d i n hydrogen a t l l O O ' F f o r 30 min.

After f i r i n g , t h e bucket i s protected a t all times by an argon atmosphere while being moved t o t h e t e s t &and.

The sampler container and holder i s

attached t o a Swagelok coupling on the pump tank r i s e r .

The volume be-

tween t h e two closed b a l l valves i s evacuated and back f i l l e d with helium a t least four times before the b a l l valves are opened t o lower t h e sample

bucket i n t o t h e pump tank.

The bucket i s held below the l i q u i d surface

f o r several minutes t o insure f i l l i n g , after which it i s raised above t h e lower b a l l valve and allowed t o cool f o r 30 min.

It i s then w i t h d r a w n t o

a position above t h e upper b a l l valve, and t h e valve i s closed.

The t o p

portion of t h e assembly, including the upper b a l l valve, i s disengaged, and t h e sample i s removed from t h i s assembly within a dry box.

The de-

tailed sampling procedure i s given i n Appendix C.

3.6 Summary of Corrosion Results The weight changes of the corrosion specimens i n MSR-FCL-1 are

plotted i n Fig. 21 f o r t h e e n t i r e operating period.

"he corrorion rate

gradually decreased during the f i r s t 9500 h r of operation. The specimens operating a t the highest temperature (lOqO째F) showed t h e greatest weight loss, which w a s equivalent t o a uniform metal removal

rate of 0.001 in./year a f t e r 9500 hr. I

The lowest corrosion r a t e occurred

during a 29OO-hr period (6700 t o 9600 h r ) , when the weight l o s s rate w a s equivalent t o 0.0003 i n ./year.

Corrosion rates would probably be reduced

i f more highly purified salt were used.

Operation d i f f i c u l t i e s a f t e r 9600 h r resulted i n an undetermined amount of air and moisture inleakage t o the s a l t system.

The drastic

e f f e c t s of t h i s inleakage are shown by the sharp increase i n t h e weight change a t a salt exposure time of 10,000 hr.

This behavior i s s i m i l a r

t o t h a t experienced i n a thermal convection t e s t loop' when w e t air came i n contact with t h e salt due t o a defective cover gas l i n e .

CONCLUSIONS A materials compatibility loop was assembled and operated f o r 10,000 hr t o investigate corrosion of Hastelloy N by sodium fluoroborate.

Automatic controls adequate t o prevent damage t o the system due t o upsets during unattended periods of operation were developed and applied.

ORNL-DWG 7t-4935R

yVI L.l

0 -10

a z

-20

c I

'3 W

-30

-40 -50

2Ooo

4000

6Mx)

8000

10,000

12.000

Fig. 21. Weight changes of removable standard Hastelloy N specimens i n flowing sodium fluoroborate (MSR-FCL-1).

Corrosion specimens and salt samples were routinely removed f o r analysis.

An e x i s t i n g salt pump design and available components were successf'ully adapted f o r salt c i & u l a t b n .

LFB, at 5000

Operation of t h e salt pump, m o d e l

rpm f o r 2000-hr periods is a maximum p r a c t i c a l service con-

d i t i o n f o r t h e grease-lubricated bearings when the pump i s b e l t driven. Degradation of t h e salt pump seal leakage o i l due t o contact with

low concentrations of BF3 has not been a problem a t a salt temperature of 950째F during 2000-hr operating periods.

I n t h e LFB pump geometry, diffusion of BF3 vapors from t h e pump bowl gas space t o t h e seal region

i s s u f f i c i e n t l y r e s t r i c t e d t h a t t h e BF3 concentration does nut become c r i t i c a l . Thus purge flows t o prevent t h i s diffusion are not necessary. This results i n a g r e a t l y simplified purge gas system. Heat t r a n s f e r performance of t h e sodium fluoroborate agrees w e l l with standard heat t r a n s f e r correlations. Sodium fluoroborate exhibits good d r a i n a b i l i t y a t about 1000OF. I n well-ventilated areas r e l a t i v e l y simple v e n t i l a t i o n and shielding enclosures may be used f o r low-temperature BFa tubing and gas panels because of t h e v i s u a l warning provided by t h e "white smoke" which forms c

from t h e reaction of BF3 with moist air. Sodium fluoroborate i s e a s i l y contaminated by a i r when i n the molten

state, and great care t o prevent air inleakage i s required i n a l l phases of operation. The corrosion rate of Hastelloy N specimens a t 1 0 g O 째 F averaged about

0.001 in./year during 9500 hr of operation and was reduced t o about 0.0003 in./year during t h e last uninterrupted 2900 h r of operation.

The

corrosion rate increased sharply with air inleakage. RECOMMENDATIONS A new system design should be provided f o r future tests t o achieve

improved pump c a p a b i l i t y and r e l i a b i l i t y , higher salt flow velocity, and a more flexible, rapid specimen removal technique.

Future tests should be designed t o allow corrosion specimen removal without dumping the salt inventory. This would prevent d i l u t i o n

48 of t h e c i r c u l a t i n g salt inventory with the salt remaining i n t h e dump

tank and s i m p l i m i n t e r p r e t a t i o n of t h e corrosion processes. The design of future salt corrosion t e s t loops should provide an emergency heating system which will allow t h e pump t o be stopped without subsequent freezing of the salt. A s u i t a b l e BF3 â&#x20AC;&#x153;scrubberâ&#x20AC;? m u s t be developed f o r future sodium

fluoroborate pump systems, so t h a t BF3 vent l i n e s can be operated f o r

long periods without plugging, a c i d formation, or back diffusion of water vapor i n t o t h e salt system. The e f f e c t of sodium fluoroborate p u r i t y on corrosion rate should be determined i n f u t u r e pumped corrosion t e s t f a c i l i t i e s .

Techniques

f o r controlled p u r i f i c a t i o n of t h e salt will be required.

Appendix A

MSR-FCL-1 FLOWSHEET

51 Appendix B MSR-FCL-1 CONTROL SYSTEM DESCRIPTION AND OPERATING F'ROCEDURES FOR UNATTENDED OPERATION CONTROL SYSTEM DESCRIPTION

Introduction The control system of M5R-FCL-1 was revised during J u l y and A u g u s t

1970 t o permit unattended operation of t h e loop during evening and nigbt s h i f t periods.

This description i s intended t o a s s i s t i n t h e operation

of t h e loop and t o provide guidance i n t h e event of any d i f f i c u l t i e s encountered during operation. The automatic control system i s designed t o t r a n s f e r t h e loop operat i o n from "design," o r normal, conditions to~"isotherma1," o r standby, conditions i n - t h e event design l i m i t s a r e exceeded o r a malfunction of equipment occurs. The p r i n c i p a l changes i n t h e control system a r e (1)t h e c i r c u l a t i n g pump i s shut o f f i n t h e event of an alarm condition, ( 2 ) loss of pump lube and cooling o i l flow i s included as an alarm condition that w i l l t r a n s f e r t h e loop t o "isothermal," o r standby, condition, and [ 3 ) a cont r o l was added t o automatically provide t h e proper amount of heat t o maintain t h e s a l t inventory molten with t h e pump o f f . Normal Operation I n t h e normal (design) mode of operation, two sections of piping between t h e pump discharge and cooler i n l e t a r e heated by d i r e c t r e s i s removed i n t h e finned cooler t o provide a temperature difference i n t h e c i r c u i t . An LFB pump c i r c u l a t e s t h e molten tance heat.

This heat

s a l t , and a constant speed blower with a manually adjusted damper provides

a i r flow f o r heat removal from t h e finned cooler.

During normal operation

t h e following conditions e x i s t : 1. s a l t i s c i r c u l a t i n g i n t h e loop and t h e

the pump l u b r i c a t i n g and cooling o i l i s flowing;

t h e two direct-resistance-heated sections a r e supplied with s u f f i c i e n t power t o provide t h e desired temperature r i s e i n t h e s a l t ;

t h e a i r blower i s on and t h e cooler housing door ( t o p of cooler housing) i s open t o provide s u f f i c i e n t cooling t o reduce salt t e m peratures t o desired level;

5 . t h e cooler d i r e c t resistance heater i s o f f . Standby Oper a t i o n The loop i s preheated by d i r e c t resistance heating during standby

operation except i n t h e pump bowl section and t h e dump tank region, which

are heated by Calrod e l e c t r i c heaters. Direct resistance heat f o r normal and standby operation i s applied through t h r e e separate control systems. The two main heater sections (used f o r normal operation) are supplied from one control system, and resistance heating of t h e e n t i r e loop (used f o r standby operation) is controlled by a second control system. The cooler i s preheated by the t h i r d separate resistance heat control system. During normal (design) operation t h i s heat will not be applied.

With a

l o s s of salt circulation, t h e cooler heater c i r c u i t and loop resistance heater c i r c u i t along with the pump bowl heat w i l l maintain the s a l t i n ventory above the freezing point.

During standby operation the following

conditions e x i s t : 1. salt i s not circulating; t h e pump i s off (Note:

t h e pump may be op-

erated, i f desired, i f t h e a l a r m i n t e r l o c k r e l a y i s manually bypassed); 2.

t h e pump l u b r i c a t i n g and cooling o i l i s flowing;

3. the loop d i r e c t resistance heater i s energized with t h e c i r c u i t arranged t o heat t h e e n t i r e loop except t h e cooler;

t h e cooler d i r e c t resistance heater i s on;

t h e a i r blower i s off and t h e cooler housing door i s closed. Automatic Transfer from Normal t o Standby Conditions A 1 6 0 0 - ~c i r c u i t breaker i n s t a l l e d i n t h e main r e s i s t a n c e heat supply

transformer secondary provides a means of t r a n s f e r r i n g from high power (normal) operation t o standby operation.

The following alarms w i l l t r a n s -

fer t h e loop from normal t o standby conditions: 1. high loop temperature,

--. T

53 2.

3. 4.

low loop temperature, l o w pump speed, l o w lube o i l flow (10 sec delay before t r a n s f e r )

Emergency Parer System

An automatic t r a n s f e r i s made t o the diesel-generator bus i n the event of a building power outage. The design includes a time delay, so t h a t f o r an outage of less than 2 sec, the loop w i l l continue on AT operation. For an outage of over 2 sec, t h e diesel generator i n the basement (which w i l l have started immediately upon a power failure) w i l l be timed i n t o provide control power, resistance heat t o the loop, resistance heat t o the cooler, pump p m r , lube o i l motor power, pump bowl heat, dump tank heat, and drain l i n e heat.

OPERATING PROCEDURES I n i t i a l Startup and Preheat

Refer t o flowsheet, Dwg. 10486-R-001, Rev. 3, f o r valve locations and functions.

1. Caution: S t a r t o i l pumps before applying heat t o the system t o prevent accidental overheating of the bearing and seals within the LFB PmP

The two l u b r i c a t i n g and cooling o i l pumps are s t a r t e d b y start switches (labeled Nos. 1 and 2) i n t h e magnetic amplifier cabinet.

The

pumps are i n parallel i n the o i l c i r c u i t , and either or both pumps can be turned on.

With the control switch i n the "off" o r "preheat" position,

the pumps can be started or stopped by the "start" switches.

With the

control switch i n the "on" or "automatic" position, operation of the lube

o i l pumps is controlled by the lube o i l flow switch. t h e standby pump w i l l be automatically started.

On loss of o i l f l o w

2. Preheat the main loop by manually closing the 400-A fused s a f e t y switch supplying t h e main resistance heater. 'Phe 1600-~ c i r c u i t breaker

is open.

Set bypass switches 13,

14, 15, 16, 17, 18, and

22 i n the

54 "preheat" position.

The dc supply t o t h e saturable r e a c t o r i s "on"

through t h e magnetic amplifier.

Set t h e potentiometer supplying power-

t o t h e saturable reactor a t -10 on t h e potentiometer dial. Preheat t h e cooler by closing t h e 30-A fused s a f e t y switch supplying the cooler resistance heater c i r c u i t . Automatic closing of

t h e contactor "CR" i n t h i s c i r c u i t i s permitted through NC contact R8-6. Bypass switch 16 (cabinet 2) should be closed ("down" position) manually t o prevent shutdown of cooler heater when r e l a y R 8 i s energized.

Close t h e 60-A fused s a f e t y switch supplying v a r i a b l e t r a n s formers through t h e 15-kVA transformer. This energizes all a u x i l i a r y heating c i r c u i t s .

Close t h e fused s a f e t y switch labeled "Ehergency Power Supply"

t o complete t h e c i r c u i t f o r diesel power i f a building power failure occurs. b

H e a t dump tank t o -gOO째F.

(The dump tank heat should be turned

on -12 hr before s t a r t u p , as t h e tank heats very slowly.) c.

Heat t h e drain l i n e (except t h e freeze valve) t o -800'F.

5. Pressurize a.

the loop with h e l i u m t o

-3 psig.

Close the 30-A fused s a f e t y switch t o the normal clutch supply

excitation. Close contact push-button, closing t h e pump starter and a l s o feeding t h e clutch. Selector switch "SS" i s set a t "off .'I Relay R5 i s b.

closed. c.

A d j u s t t h e pump speed t o -500 rpm (cabinet 1).

S e t t h e low pump speed a l a r m a t 400 rpm.

The pump seal purge should be flowing through t h e thermal con-

d u c t i v i t y c e l l a t -80 cc/min.

After all loop temperatures are a t 850 t o 1200째F, position valves f o r t h e loop f i l l i n g operation as follows. Be sure all heater l u g temperatures are a t least gOO째F. The valve p o s i t i o n shown w i l l

allow pressurizing the dump tank from one of t h e helium cylinders, while t h e second cylinder i s used t o maintain loop purge gas flow and pressure.

55 hen

Closed

HV 13 HV 16 24 HV 35 HV 82

HV i g HV20 HV 21 HV 22 HV 26 HV 27 HV 28

HV 30

HV46 HV 81 HV 83 HV 84 W 117 RV 139

8. A d j u s t t h e flow through FI 17 by opening HV 21 t o -0.2 ft3/hr 9. Close HV 21.

10. Thaw t h e freeze plug- by closing HCV 110 and turning up t h e heat on t h e f i l l l i n e (Variac 8, panel 3).

ll. Open HV 22 and HV 81 t o pressurize t h e dump tar-& slowly t o push salt i n t o loop. Dump t a n k pressure of -5 p s i above loop i s required f o r loop f i l l . (PI 116 i s located i n pump enclosure.) 12. Slow t h e gas flow t o sump by closing HCV 16 when t h e lower pump probe l i g h t comes on.

13. Close HCV 16 when t h e top pump probe l i g h t comes on. 14. Close HV 24. 1 5 - Open HV 26 s l i g h t l y t o drop the salt l e v e l u n t i l the top probe I

l i g h t goes off.

16. Close HV 26. 17. Turn off Variac 8 and start air flow through t h e freeze valve by opening HCV 110.

18. When t h e freeze valve i s frozen, open HV 26 t o vent t h e tank t o -4 psig. 19. Close HV 81, 26, and 82. 20.

dump

Check t h e pump seal purge and t h e thermal conductivity c e l l

recorder. 21.

Blower and damper control permissive r e l a y

by manually closing switch 15 ("dawn" position).

R8 i s now energized

When t h e relay i s

closed, it seals itself i n through contact ~ 8 - 3 ,paralleling switch 15.

I n order t o permit shutdown of t h e blower and damper on long-time loss

of power, switch 15 i s now opened manually ("up" o r normal operating position) The cooler blower main control power (switch and breaker on

t h e breaker rack) should be off t o prevent blower s t a r t u p u n t i l needed.

Increase t h e pump speed t o t h e desired l e v e l .

For 4 gpm (-10 f p s ) a speed of 4800 t o 5000 i s adequate. Check pump f o r excessive ope r a t i o n a l noise, vibration, o r R possible o i l leak i n the r o t a r y union. 23. With the loop temperatures above 950째F, manually close t h e 22.

1 6 0 0 - ~breaker (located on the east side of t h e loop enclosure) and slowly increase the main resistance heat potentiometer t o -& and I$ turn off t h e cooler heater by placing switch 16 i n the operate (up) position. 24.

When loop temperatures start increasing, t u r n on t h e cooler

blower using t h e start switch and the breaker on the breaker rack.

The

s l i d i n g damper on the blower intake should be closed. 25. Open the door on t h e t o p of the cooler housing and engage t h e solenoid, which w i l l hold t h e door open. 26.

open t h e s l i d i n g damper a l i t t l e a t a t i m e as required t o adjust

t h e loop temperature t o t h e desired l e v e l .

Lock t h e damper i n t h e f i n a l

position f o r long-term operation.

27.

mace a l l bypass switches (1through 18, and 22) i n the operate

or automatic position. 28.

Place t h e building a l a r m switch (No. 23) i n t h e "up" position

t o a c t i v a t e the building alarm and s i g n a l t o t h e plant s h i f t supervisor

(RS) 29. Make f i n a l adjustments on the temperature c o n t r o l l e r (TIC-1, cabinet 2) and t h e blower damper, as required, t o obtain the desired

temperatures on t h e metallurgical specimens. Main Transformer -How t o Control

The power t o t h e main power supply i s controlled by d i r e c t current on a saturable reactor.

With t h e potentiometer adjustment knob (Mag.

Amp. Cab.) a t zero, there is s t i l l some dc current i n t h e reactor which gives what i s c a l l e d "dc leakage current" t o the heater section.

If t h e

F'yr-o-vane c o n t r o l l e r cuts off dc completely, as evidenced by the main power supply alarm l i g h t coming on, t h e r e i s s t i l l available w h a t i s

termed "minimum leakage current" t o t h e heater section. Should t h e temperature reach t h e set point of t h e Pyr-o-vane,

the

dc w i l l be cut off and t h e loop t r a n s f e r r e d t o isothermal conditions.

Resistance heat w i l l be reapplied as soon as temperature has dropped below the set point. Therefore, t h e Pyr-o-vane gives "on-off" control of temperature should a high-temperature alarm condition occur. When an a l a r m condition has occwred and t h e loop has been transferred t o the standby cond.Lhion, power f o r resistance heating of the

e n t i r e loop i s controlled through t h e second potentiometer (Mag. Amp. Cab.), which m u s t be preset t o deliver t h e correct amount of power t o

keep loop temperatures above t h e salt liquidus temperature (725'F) but below -1200'F.

The correct s e t t i n g f o r t h e isothermal heat i s deter-

mined during s t a r t u p and i s indicated on t h e potentiometer scale, Position of Control Switches During Normal Owration

!The following l i s t of switches and controls includes a brief explanation of each as t o its function and position during normal operation.

Note:

The "up" position i s t h e proper position f o r a l l switches

during normal operation with a AT, except switch 22, which i s down o r i n t h e "autamatic" position. 1. Control Cabinet No. 1

a. Switches 1through 12 are alarm silence switches associated with each of t h e 12 alarm l i g h t s . These switches a r e f o r acknowledging t h e alarm condition and w i l l silence the b e l l only. Whenever any of these switches are i n t h e "down" (acknowledge) position, the blinker l i g h t w i l l be on. b.

Clutch supply selector switch ("SB") will be i n t h e "off" po-

s i t i o n t o give normal power supply t o the clutch.

The auxiliary clutch

supply i s disconnected. c.

Switch 20, t h e building and plant s h i f t supervisor (PSS) alarm

bypass, should be i n t h e "up" position t o allow building and PSS signal. d.

moved.

Switch 21, t h e loop containment a i r flow alarm, has been reThis alarm now is lwated on t h e "Tigerman" annunciator, and

t h i s switch i s no longer needed.

Switch 22, during normal operation, should be i n "automatic" (down) position t o allow pump shutoff f o r high and low temperature and e.

58 On "test" position t h e switch prevents stopping of the pump automatically except on l o s s of o i l flow;

l o w pump speed.

Control Cabinet No. 2

a. 'Switch 13, t h e low-temperature automatic-operation by-pass, will be l e f t in. open o r "operate" position.

operations due t o low temperature.

When closed, it prevents automatic

Note:

This does not by-pass t h e audi-

ble and visible alarms. b.

Switch

14, t h e

i n "operate" position.

automatic operation bypass switch, w i l l be l e f t I n "test" position

it w i l l prevent any of t h e

automatic actions from taking place and i s t o be placed i n "test" position only when t e s t i n g the various alarm c i r c u i t s and during a c t u a l "preheating" or "thawing" of t h e loop. Switch 15, t h e automatic operation relay reset, will be l e f t i n t h e closed or "operate" p o s i t i o n t o allow automatic operation i n the c.

event of an alarm condition.

The switch i s placed i n "operate".position

soon after s t a r t u p of a loop t o allow s e a l - i n of relay 8, which d i r e c t l y performs the automatic operation.

Thereafter, it w i l l be,used only t o

"reset" the automatic operation c i r c u i t s (after t h e cause f o r same has been cleared and t h e loop i s ready t o go back on AT) d.

Switch 16, t h e cooler heater control switch, w i l l be l e f t i n

open o r "operate" position.

'mis 'allows

relay a c t i o n t o supply resistance

heat t o t h e cooler i n the vent of an alarm condition requiring it.

"preheat" position it w i l l allow heat t o be applied t o t h e cooler without an alarm condition.

Switch

17, t h e main resistance heater switch,

t h e "operate" o r closed position. t o t r i p during an alarm condition.

w i l l be l e f t in

This W l l allow t h e l600-A breaker I n "preheat" position it w i l l prevent

tripping of the breaker automatically. f.

Switch 18, t h e low-speed and low-temperature reset, wlll be l e f t

on closed or "operate" position.

This serves a s ' a reset f o r e i t h e r the

low-temperature o r t h e low-clutch-speed alarm.

When t h e switch is reset

Âś

after a low-clutch-speed alarm, it w i l l automatically place the clutch supply back on t h e normal supply, provided it i s available. When reset after low-temperature alarm, it w i l l reset t h e alami relay only.

_ -

g. h.

Switch 19 i s nut i n use. A summary table of t h e switch positions i s presented i n Table

B.l.

Heater and Gas Controls During Normal Operation 1. The cooler heat control variable transformer w i l l be preset dur-

ing s t a r t u p t o provide s u f f i c i e n t heat t o t h e cooler t o prevent freezing. This s e t t i n g (indicated on f r o n t dial) should be changed only i f the cooler heater c i r c u i t i s i n use and an adjustment of cooler temperatures

i s necessary. 2. The cooler preheat voltage meter gives an indica-bion of the voltage across t h e cooler lugs during application of power t o the cooler

It is t h e only positive indication of power being applied (other than temperatures) t o t h e c o i l . coil.

The loop resistance heat control ( t h e potentiometer i n the Mag.

Amp. Cab.) w i l l be preset during s t a r t u p t o provide s u f f i c i e n t heat t o

the loop piping (except cooler) t o prevent freezing i f t h e loop i s automatically t r a n s f e r r e d t o isothermal or standby.

The proper s e t t i n g Fs

indicated on t h e potentiometer dial.

The catch basin flowmeter should have a s l i g h t bleed of helium

(-80 cc/mln) as indicated by t h e f l o w indicator, FI 91, i n

the BF3

cubicle.

The pump pressure should be between 6 and 8 pslg ( t h e pressure

recorder is i n t h e pressure recorder cabinet).

6. The dump tank pressure should be between 3 and 4 psig. 7. The equalizer and vent valves should be closed (HV 84 and HV 83) Abnormal Conditions 1. Switch Positions During Standby During standby (preheat), switches

17, 18, and 19 are open ("down"

position), as shown by the operation of alarm l i g h t L 11. During "operate," a l l three switches are closed ("up" position) and t h e l i g h t i s o f f .

_ _- .

Table B . l .

. . . . . . I

.~.. ._, . ~ ~ ~. -

. . . ..

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

.-.... .

Control switch l i s t Position

Description

Number

Shuts off l o s s of normal clutch supply alarm No longer i n use Shuts off low-clutch-speed alarm Shuts off l o s s of power t o pump motor alarm Shuts off loss of main power alarm Shuts off blower a l a r m Shuts o f f loop high-temp. alarm Shuts off loop low-temp. alarm Shuts off low lube flow alarm Shuts off loss of cooler power alarm Monitors switches 17, 18, 19 Monitors switches 13, 14, 15, 16 Low-temperature control bypass T i m e delay r e l a y test switch Reset f o r preheat t r a n s f e r control Cooler preheat control c i r c u i t Trip c i r c u i t bypass f o r main c i r c u i t breaker 'Permits low-temperature and low-pump-speed operation Building and PSS alarm bypass No longer i n use Permits pump operation a t high and low temperatures

1 2

3 4 5 6 7 8 9 10 11 12

13 14 15

16 17 18 20 21 22

Location

Normal operation

Preheat operation

Control cab. 1

Down

Control Control Control Control Control Control Control Control Control

cab. cab. cab. cab. cab. cab. cab. cab. cab.

1 1 1

Down Down Down Down

1 1 1 1

UP UP UP UP UP UP UP UP UP

Control Control Control Control Control

cab. cab. cab. cab. cab.

2 2 2 2 2

UP UP UP UP UP

1 1

DOWn

D0W-n DOWn Down Down D m Down Down Down D m DOWn

Control cab. 2 Control cab. 1

UP UP

DOWn

Control cab. 1

Down

61 L d

Switch 11 must be ffoff'f during "preheat" t o shut off b e l l and flasher. When closed during "operate," switch 11 w i l l permit t h e b e l l and f l a s h e r t o f'unction should any of t h e three switches be opened manually (human error). During "preheat," switches 13, 14, 15, and 16 are closed ("down" position), as sham by t h e operation of alarm l i g h t L 12.

During "operate," a l l four switches are open ("up" position) and the l i g h t is

off.

Switch 12 must be "off" during "preheat" t o shut off the b e l l and

flasher.

When closed during "operate," swikch 12 w i l l permit the b e l l

and f l a s h e r t o f'unction i n event any of the four switches should be closed manually (human e r r o r ) . 2,

Pump Speed Low

Low pump speed w i l l cause t h e following actions automatically: a.

The pump ac motor, and thus t h e circulating pump, i s stopped.

The blower i s stopped.

The door on t o p of cooler housing i s closed.

The 1 6 0 0 - ~breaker i s opened, and t h e loop i s resistance heated around e n t i r e c i r c u i t except f o r t h e cooler c o i l . e. The power supply t o t h e main loop resistance heater i s switched d.

from the main loop heat control mode t o t h e isothermal heat control mode, which i s preset t o provide t h e reduced heat t o t h e loop, as required, on l o s s of salt circulation. f.

g. office.

The resistance heat t o t h e cooler c o i l i s turned on. A signal i s transmitted t o t h e Plant S h i r t Superintendent's (PSS)

Loop Temperature High A high loop temperature w i l l cause t h e same actions as described

i n 2, above. c

Loop 'Pemperature Low A low-temperature alarm w i l l cause t h e same actions as i n 2, above.

5 . High o r Low Loop Heater Parer High o r low loop heater power w i l l give l o c a l , building, and PSS

alarms only.

6 . High or Low Loop Pressure High o r low loop pressure w i l l give l o c a l , building, and PSS alarm only *

Loss of Pump Lube O i l Flow If t h e pump lube o i l flow falls below a preset value, t h e second

o i l pump w i l l be started automatically.

If flow i s not returned within

10 sec, the ac pump drive motor (and thus t h e salt c i r c u l a t i n g pump) i s stopped.

I, _-

63 Appendix C MSR-FCL-1 SALT SAMPLING PROCEDURE 1. I n s t a l l t h e sample bucket i n the sample holder (Ref. Dwg

10486R008E. 2.

Fire sample bucket a t lower end of sample tube i n the Reactor

Chemistry furnace at

6oo0c f o r

30 min under hydrogen gas.

Be sure t o

l i g h t t h e hydrogen vent on the furnace during f i r i n g .

L i f t t h e sample bucket out of t h e fâ&#x20AC;&#x2122;urnace t o j u s t below first

f o r 30 min. L i f t the sample bucket above t o p b a l l valve (HV 114) and close

b a l l valve; l e t it cool under an argon gas purge

the valve t o i s o l a t e t h e bucket with 10 psig of argon over pressure.

Close gas valve HV 137.

Remove t h e sample holder assembly from t h e fur-

nace.

5. I n s t a l l the sample holder assembly on the pump sample l i n e , 6. Set t h e gas valves i n t h e following order ( R e f . Flowsheet Dwg. 10486R001E): open HV 61 ( f o r pump purge); open HV 13; open W 14 fully; open HCV 16, 19; close HV 20, 21, 22, 119. 7. Set t h e vacuum valves i n the following order: close HV 132, t u r n on t h e vacuum pump, open HV 122, 124, 138, 115, 113, 136. Pump t h e system down t o HV 137 and b a l l valve 112.

8. Close HV 138 (vacuum valve). 9. Open HV 119. Pressurize t h e system with helium t o HV 137 and b a l l valve HV 112. 10. Open HV 114 and HV 137. 11. Close HV 119 (gas valve) 12.

Open HV 138 (vacuum valve).

13. Alternately pressurize t h e system with helium and pump the syst e m down with a Welch mechanical vacuum pump a t least four t i m e s . 14. Close HV 138 and open HV 119. 15. Open HV 112 (lower b a l l valve) and push the sampler t o t h e bottom of t h e pump bowl; leave it i n t h i s position f o r 5 t o 10 min.

16. L i f t t h e sampler above HV 112 (lower b a l l valve) and close valve HV 112.

17. Let t h e sample cool f o r about 30 min, 18. Close HV 119; open HV 138 .(pump on t h e sample t o remove BFa gas)

19. Close HV 138; open HV 119; lift t h e sample above HV 114 and close HV 114; close HV 136, 113, 137, 115, 119. Tighten t h e Swagelok f i t t i n g on the push rod. 20. Remove t h e sample holder a t t h e Swagelok f i t t i n g between HV

114 and 112 and between IN 115 and 137. 21.

Close HV 13..

22. Deliver t h e sample t o Metals and Ceramics personnel f o r analysis.

Internal Distribution 1. J. L. 2. C. F. 3. S. E. 4. C. E. 5. E. S , 6. E. G. 7. C. J. 8. G. E. 9. E. J. 10. R. B. 11. D. L. 12. J. W. 13. W. B. 14. J. L. 15. J. H. 16. J. R. 17. S. J. 18. W. P. 19. D. E. 20. L. M. 21. A. P. 22. L. C. 23. C. H. 2 & ? 7 . P. A. 28. W. R.

29. 30.

31. 32. 33.

34. 35-39. 40. 41. 42. 43. 44.

Anderson Baes Beall Bettis Bettis Bohlmann Borkowski Boyd Breeding Briggs Clark Cooke Cottrell Crowley mvan Distefano Ditto Eatherly Ferguson Ferris Fraas Fuller Gabbard Gnadt Grimes A. G. Grindell R. H. Guymon w. 0. HELIVIS P. N. Haubenreich R. E. H e l m s H. W, Hoffman W. R. Huntley W. H. Jordan P. R. Kasten J. J. Keyes J. W. Koger A. I. Krakoviak

45 46. 47 48. 49 50 51 52 53 54 55 * 56 57 58 59 60. 61-62. 63 64. 65 66. 67 68. 69 70 71* 72 73 74 75 76 77 78. 79 80-81.. 82. 83-86. 87 9

M. T. R, R.

I. S. N. E. E. C. K. E.

Lundin Lundy Lyon MacPherson H. McCoy H. McCurdy C. McGlothlan L. McNeese J. R. McWherter H. J. Metz A. S. Meyer A. J. Miller R , L. Moore E. L, Nicholson A. M. Perry R. C. Robertson M. W. Rosenthal H. C. Savage Dunlap Scott J. H. Shaffer M. R. Sheldon M. J. Skinner A. M. Smith A. N. Smith I. Spiewak R. D. S t u l t i n g D. A. Sundberg R. E. Thoma J. R. Weir M. E. Whatley G. D. Whitman L. V. Wilson G a l e Young H. C. Young Central Research Library Y-12 Document Reference Section Laboratory Records Department Laboratory Records (RC)

Ekternal Distribution

88. 89. 90. 91.

D. F. Cope, RDT, SSR, AEC, ORNL David Elias, USAEC, Washington, DOC. 20000 Norton Haberman, USAEC, Washington, D.C. 20000 K e r m i t Laughon, USAEC, OSR, ORNL

66 â&#x20AC;&#x2122;

92.

T. W. McIntosh, U W C , Washington, D.C.

20000

93. M. Shaw, USAEC, Wwhington, D.C. 20000 94-96. Directorate of Licensing, USAEC, Washington, D.C. 20545 97-98. Directorate of Regulatory Standards, USAEC, Washington, D.C. 20545

99-115. Manager Technical Information Center, AEC, fox ACRS 116. Research and Technical Support Division, AEC, OR0 117-118. Technical Information Center, AEC