ORNL-TM-0528 by Jon Morrow

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O A K RIDGE N A T I O N A L LABORATORY operated by UNION CARBIDE CORPORATION for

the

U.S. ATOMIC E N E R G Y COMMISSION

ORNL-~. -.. TM- 528

DESIGN A N D OPERATION OF FORCED-CIRCULATION CORROSION TESTING LOOPS WITH MOLTEN SALT

J. L, Crowley W. 8. McDonald D. L. Clark

NOTICE This document contains information of a preliminary nature and was prepared primarily for internal use at the Ook Ridge National Laboratory. I t i s subiect t o revision or correction ond therefore does not represent a final report. The information i s not to be abstracted, reprinted or otherwise given public dissemination without the approval of the ORNL patent bronch, Legal and Information Control Department.

LEGAL NOTICE T h i s report was prepared as on account of Government sponsored work.

Neither the United States,

nor the Commission, nor any person acting on behalf of the Commission:

A. Makes any warranty or representotion, expressed or implied, w i t h rmspoct t o the accuracy, completeness, any

or usefulness of the information contained i n t h i s report, or that t h e use of

information.

apparatus,

method,

or process disclosed

i n t h i s report moy not infringe

p r i v a t e l y owned rights; or

6. Assumes ony l i o b i l i t i e s w i t h respect t o the use of, or for domoger r e s u l t i n g from t h e use o f any information, apparatus, method, As

used i n the obove,

contractor or

"person

or process disclosed i n t h i s report.

a c t i n g on beholf o f the Commission"

includes any employee or

of the Commission, or employee o f such controctor. to the extent that such employee

controctor

of the Commission,

w employee o f such controctor prepares, dinseminotes. or

provides access to, ony informotion pursuont t o h i s employment or h i s employment w i t h such controctor.

...

or controct w i t h the Commission,

ORNL-TM-528

C o n t r a c t N o . W - 7405-eng-26

R e a c t o r Division

DESIGN AND OPERATION OF FORCED-CIRCULATION CORROSION TESTING LOOPS WITH MOLTEN SALT J. L . C r o w l e y W . B. M c D o n a l d D. L. C l a r k

D a t e Issued

MAY - 1 1963

OAK RIDGE NATIONAL LABORATORY Oak R i d g e , Tennessee operated by

UNION CARBIDE CORPORATION for t h e U . S . ATOMIC ENEBGY COMMISSION

iii

CONTENTS

Page

Ab st r a c t

Introduction

D e s c r i p t i o n of Test Loop and A u x i l i a r y Equipment

Alarm and Automatic-Action Controls

Operation and Maintenance of a T e s t Loop

Summary

Acknowledgments

. DESIGN

AND OPERATION OF FORCED-CIRCULATION

CORROSION TESTING LOOPS WITH MOLTEN SALT W. B. McDonald

J. L. Crowley D. L . Clark Ab s t r a c t

StandardLzed t e s t f a c i l i t i e s were developed and operated f o r i n v e s t i g a t i n g t h e c o m p a t i b i l i t y of s t r u c t u r a l materials and flowing molten f l u o r i d e s a l t s . The s t a n d a r d l o o p accommodates v a r i o u s combinations of materials, f l u i d s , flow r a t e s , and t m p e r a t u r e d i f f e r e n t i a l s and p e r m i t s f a b r i c a t i o n of comjtonents i n s u f f i c i e n t q u a n t i t y f o r c o s t r e d u c t i o n . The t e s t l o o p c o n s i s t s of a pump, two h e a t e d s e c t i o n s , a cooled s e c t i o n , a d r a i n tank, and a f r o z e n plug-type v a l v e . Automatic c o n t r o l s and equipment were developed t o p r e v e n t s o l i d i f i c a t i o n of t h e s a l t m i x t u r e s (m.p., 800 t o 1100°F) i n t h e event of a loss of power. Most t e s t loops are f a b r i c a t e d of 0.5-in.-o.d., 0.045-in.w a l l tubing, and t h e y o p e r a t e w i t h a temperature d i f f e r e n t i a l of up t o ZOOOF, a maximum w a l l temperature i n t h e range 1200 t o 1500C’F, and a s a l t flow r a t e of up t o 3 gpm. Twenty-five t e s t l o o p s have been o p e r a t e d f o r a n accumul a t e d o p e r a t i n g time--of Z90,OOO h r . I n d i v i d u a l 1oops have been o p e r a t e d continuously f o r more t h a n one y e a r .

Introduction Mixtures of molten f l u o r i d e s a l t s have been i n v e s t i g a t e d e x t e n s i v e l y f o r a p p l i c a t i o n i n r e a c t o r systems as f l u i d f u e l s or as h e a t t r a n s f e r media.

The c o m p a t i b i l i t y of a p a r t i c u l a r s a l t mixture with a proposed

c o n t a i n e r a l l o y i s detemnined, i n p a r t , by t e s t s with thermal-convection loops,’

and t h e most promising combinations of s a l t mixtures and

s t r u c t u r a l material are i;hen s t u d i e d i n f o r c e d - c i r c u l a t i o n c o r r o s i o n

t e s t loops.

These l o o p s simulate a l l e s s e n t i a l r e a c t o r o p e r a t i n g con-

d i t i o n s except r a d i a t i o n m 2 The t e s t s t a n d s and l o o p s have been s t a n d a r d i z e d t o permit ready repilacement and t o minimize f a b r i c a t i o n c o s t s and i n s t a l l a t i o n time. Many mixtures of mo:lten salts have been t e s t e d .

The b a s i c con-

s t i t u e n t s of t h e s e have -2een t h e f l u o r i d e s of sodium, l i t h i u m , beryllium, t

. 2

I z i r c o n i m , thori,Jm, ar2d uracium i n v a r i o u s p r o p o r t i c n s t h a t g i v e m e l t i n g temperatures g e n e r a l l y f a l l i n g i n t3e 800 t o llOO0F range. and d e n s i t y v a r y with each mixture.

ct:r:t.ipoLse

en?

t h e anmmt of

:hiitk?

t y p i c a l s a l t rnlxt?ire k r s h Tiiscosity of 10 t. !3

sp~.cZZj_cgya:iity of 2 . 4 et I I C O F.

T'-p

s a l t mixtures

c orz~.:riFngk e r y L l i z - e q dre s t z i n g e c t saf z t ; ~p-scaut,ions .

Viscosity

The v i s c o s i t y i n c r e a s e s with t h e

axount of b e y j r l l i ~ xFrese:?_t wid t k e der:sit,y f z c x e s e s h?ez,vy elcment,s prest

t.0

p r e v e n t ex-

posure of p e r s o x e l t o t - 2 - L ~t o x i c n a t e r i a i . rn p r e d i c t ecc:?.retelg c o r r o s i o n r a t e s f o r power r e a c t o r s , t h e t e s t s r m s t n e c e s s a r i l y be of long-term ciuratioi?.

Tl.e t z s t sts~zcic o n t r o l

s p t m w z s t?ie:mefcr? ciesigced n o t only t o m & i E t & i c .the n e c e s s a r y t e s t co_rditions for i o ~ gp e r i o d s of opera+,ior bat aisc t o provide a x t o m t i c p r c t e c t i o x agaiwt s c l i 2 f f i s a t L o n cf t h e s a i t i n t3e system.

Sime

melting of t h e s a i t iinpcses sewx-e stresses or? t h e c o c t a i n e r w a l l ,

re-

m e l t i n g a f t e r s o l i d i f l e a t i m migkt cause premature f a i l u r e of t h e l o o p .

The t e s t l c o p i s I l l s s t r e t , e d i n F i g . 1. punp,, two h e a t z d sectioris, plug-type -;sive.

m, J.LY

l o o p c o e s i s t s of a

cooled sect.ion, a ?.rc,ic t.a;-k, and a f r o z e n -

. A l l w e t k d p a r t s of t h e i o o p are f a - 9 r i c a t e d of t h e

Loop t u b i r g s i z e i s s e l e c t e d t o p r o v i d e t h e p r o p e r

alloy beicg studied.

c o n d i t i o x i f o r e l e @ t r F c a l = r e s l s t a ~ chee a t i n g and t o g i v e a p r e s s u r e drop

a t d e s i g n flo-+.that, i s c m s i s t e r i t w i t l ; t h e pwnp c a g a b i i i t y . diasrm

52'

t:?? IYZ~--LSE-S~.-

fi1er-t COITF;:~

A flow

c i r c u 2 z and t h e a a x i l i e r y co.ntrols f o r t h e

g:es 225 c:tflitLt-s is sh.owr;

ir,

Fig" 2 .

A stz,n??ard lcoy, sv.ypar-kd ky i t s mobile bily i s p i c t w e d i n

Fig. 3 .

T k i s s-tec2zrd I m p was developed from e x p e r i e i x e g a i c e d

ir?

zaxy t e s t s t o accsmiodate t h e v a r i m s combinatiozs of materials, f l u i d s ,

-~- l o wr a t e s , a

temperttu:?e g r e d i e s t s de s i res-

Such s t a n d a r d i z a t i on

has p e r m i t t e d f'ehricr,tion of components i n q u a n t i t y f o r both c o s t r e dimction ar_? eese zjf a.ese%bly-o The i n t e r c h a n g e a 3 i l i t y of t h e t e s t l o o p s

and star& .~,LIows+;;I?J

f'a-arlcat.ior, of stacd5y t e a t loop zssemblies f o r

quick replasemezt v i t h o.d.,

O.C45-in.-wall

?xLrlim.m of dowr? the.

-Lg.-oiii?g

F o r x o s t tests,

O.5-in.

h a s been fcund t o 3e s u 5 t a b l e .

‘

UNCLASSIFIED ORNL-LR-DWG 64740

-:r 110kva

POWER

SUPPLY

1600-amp

BREAKER

-~“B”

(0 kva POWER

Fig.

Molten-Salt

Corrosion

Testing

SUPPLY

Loop and Power Supplies.

Unclassified Photo 34533

MAGNETIC CLUTCH 8

5HP

SHAFT AN0 SEAL OIL

FLOW ALAR

L Z E", ; : , , COOLING WATER SUPPLY

LV ;E\

EQUIPMENT IDENTIFICATION

AIR

AIR VENT

FI I

I 1 DRAIN TANK

FG-FLOW INDICATING GLASS, NON- CALIBRATED F I -FLOW INDICATOR HCV-HAND- ACTUATED CONTROL VALVE HV-HAND-ACTUATED BLOCK VALVE PI-

PRESSURE INDICATOR

PV-PRESSURE

CONTROL VALVE

XV-CHECK VALVE TI- TEMPERATURE INDICATOR SI-SPEED SC-SPEED

INDICATOR CONTROL

LL-LEVEL

LIGHT

PRESSURE CONTROL VALVE -W- VALVE, NORMALLY CLOSED Q VALVE, NORMALLY OPEN

+CHECK

VALVE ( X V )

HELIUM SUPPLY

Fig. 2.

Flow Diagram of Molten S a l t Loop and U t i l i t i e s .

Unclassified

Fig. 3. Dolly.

Photograph of Molten-Salt Corrosion Testing Loop on Mobile

The flow rate, Reynolds number, p r e s s u r e drop, and power r e q u i r e d f o r t h e h e a t e r s e c t i o n s a r e c a l c u l a t e d using t h e physical p r o p e r t i e s of t h e p a r t i c u l a r s a l t mixture an2 t h e perfolrmance c h a r a c t e r i s t i c s of t h e pump. A l o o p p r e s s u r e drop ( f e e t of head) vs flow (gpm) curve i s determined by m i n g t h e p h y s i c a l p r o p e r t i e s of t h e molten s a l t t o be t e s t e d and t h e

Ey superimposing t h i s c m v e

geometry of t h e l o o p .

on t h e pump o p e r a t i n g

c h a r a c t e r i s t i c curve, as shown i n F i g . 4, t h e d e s i r e d flow r a t e i s determined w i t h i n t h e L i r r i t a t i o n s of aliowzble puxp speed. The e l e c t r i c a l r e s i s t i v i t y of +,he rc;ol-Len s a l t i s enough h i g h e r t h a n t h a t of t h e metal c o n t a i n e r w a l l s t h a t it can b e n e g l e c t e d i n determining t h e power requiremects of t h e hea-cer s e c t i o n s .

The t r a n s f o r m e r v o l t a g e

r e q u i r e d f o r t h e p a r t i c u l a r s a l t mixture shown i n P i g .

4 was

calculated

according t o t h e e l e c t r i c a l r e s i s t a n c e of t h e h e a t e r s e c t i o n tubing, t h e flow rate, and t h e d e s i r e d b d k f l u i d temperature d i f f e r e n c e .

The power

r e q u i r e d of t h e t r a n s f o r m e r w a s 58.8 Kw a t 1250 amp and 47.2 v o l t s . two h e a t e r s e c t i o n s , 96 i n . and

lo9

i n . i n l e n g t h , are connected t o t h e

power supply t r a n s f o r n e r i n p a r a l l e l and c a r r y tively.

The s h o r t e r f i r s t s e c t i o n

The

(96 i n . )

665 and 585 amp, respec-

h a s l e s s r e s i s t a n c e and

imparts a h i g h e r h e a t f l c x where t h e b u l k f l u i d temperature i s t h e lowest.

This arrangement r e s u l t s i c approximately e q u a l maximum w a l l

ternperatires a t t h e o u t l e t of b o t h h e a t e r s .

A w a l l temperature and b u l k it

f l u i d t e n p e r a t z r e p r o t i l e of c o a d i t i o l s i s s h o ~ nZr F i g .

t y p i c a l l o o p while i n o p e r a t i o n a t t e s t The 12R h e a t i n g i s a p p l i e d only t o

s t r a i g h t s e c t i o n s of t h e tu5ixgg, during ~ o r m a loperation, t o e l i m i n a t e h o t s p o t s caused 5y poo? flow d i s t r i b u t i o n i n t h e t u b i n g bends.

Two

h e a t e r s e c t i o n s are used t o reduce t h e o v e r - a l l l e n g t h of t h e l o o p t h a t wo-dd be necessary t o o b t a i n t t e d e s i r e d f l u i d temperature with one contincous heater section.

The flow o f c u r r e n t i s r e s t r i c t e d t o t h e h e a t e r

sectiofis during o p e r a t i o n a t t e s t c o n d i t i o n s by t h e nethod of attachment t o t h e transformer.

O x t e r m i n a l of t h e t r a n s f o r m e r i s connected t o t h e

o n t l e t of t h e second h e a t e r s e c t l o n and t o t h e l d e t of t h e f i r s t h e a t e r section.

The o u t l e t of t h e f i r s t h e a t e r and t h e i n l e t of t h e second

h e a t e r are siar1lar;y

connectec! t o t h e o t h e r t r a n s f o r m e r t e r m i n a l .

l o o p i s grouEde3 a t t k pimp, whlie t h e r e n a i n d e r of t h e l o o p i s

The

110

U N C L A SS IF1ED ORNL- LR-DWG 65065 I

100

80 70 A

+ c Y

50 40

30 20

FLOW (gpm)

Fig. 4 .

Performance C h a r a c t e r i s t i c s of C e n t r i f u g a l Pump, Model LZB.

UNCLASSIFIED ORNL-LR-DWG 65066

1300 1250

1200

i150 l-

5 I-

(100 4050

to00 950

400

200

300

400

5 00

600

LENGTH (in.)

Fig. 5 .

Temperature Profile of Corrosion Loop a t T e s t Conditions.

9 e l e c t r i c a l l y insulated. A t t e s t c o n d i t i o n s , from 350 t o TOO amp of 60-cycle a l t e r n a t i n g c u r r e n t flows i n each h e a t e r s e c t i o n a t a p o t e n t i a l of 25 t o 50 v. E l e c t r i c a l current' i s s u p p l i e d t o t h e h e a t e r s e c t i o n s through a n i c k e l

lxg welded t o a t h i c k - w a l l e d a d a p t e r s e c t i o n of t h e l o o p . 'I3e power f o r t h e h e a t e r s e c t i o r , i s s c p p i i e d by a 110-kva t r a n s f o m e r kaving a low-voltsge h i g h - c u r r e n t secondary winding, w i t h a

s a t u r a b l e - c o r e r e a c t o r on t h e primary s i d e .

A proportional-control

pyrometer r e g u l a t e s t h e 3-c v o l t a g e t o t h e s a t u r a b l e r e a c t o r and d e t e r n i n e s t h e v o l t a g e a p p l i e d t o t h e h e a t e r s e c t i o n of t h e l o o p by t h e main power t r a n s f o r m e r .

The m o u n t of power which may be a p p l i e d t o t h e

h e a t e r s e c t i o n i s l i m i t e 3 by a maximum-adjustment r h e o s t a t t h a t l i m i t s t h e d i r e c t current availcable t o t h e saturable reactor. A l o o p high-temperature alarm i s designed t o c u t o f f t h e d i r e c t

c u r r e n t t o t h e s a t u r a b l e r e a c t o r and t o reduce t h e power t o a minimum leakage v a l u e .

When t h e l o o p temperature a g a i n drops below t h e alarm

s e t p o i n t , t h e automatic a c t i o n r e l a y i s r e s e t and t h e power i s rea p p l i e d a t t h e rate p r e v i o u s l y s e t .

The high-temperature alarm t h u s

s e r v e s as a n "on-off" c o Q t r o l of t h e power i f a n emergency c o n d i t i o n occurs. The t r a n s f o r m e r i s connected t o t h e l o o p h e a t e r l u g s by a 5OO,OOOc i r c u l a r - m i l l s c a b l e through a 1600-amp b r e a k e r .

During normal o p e r a t i o n

t h e connections of t h e h e a t e r s e c t i o n are such t h a t t h e c u r r e n t flow i s

confined t o t h e two h e a t e r s e c t i o n s

(4 connections

t o t h e loop).

How-

ever, when it i s necessa:ry t o p r e h e a t o r p r o v i d e emergency h e a t i n g t o

the e n t i r e loop, t h e 1600-amp b r e a k e r shown i n F i g . 1 i s t r i p p e d , l e a v i n g only two connections t o t h e l o o p .

Thus t h e e n t i r e loop, with t h e ex-

c e p t i o n of t h e c o o l e r c o i l , i s h e a t e d by t h e formation of two p a r a l l e l p a t h s of n e a r l y e q u a l r e s i s t a n c e . A downflow c e n t r i f u g a l sump pump designed a t ORNL i s used. of t h e s e p u ~ p shave been f a b r i c a t e d of f o u r d i f f e r e n t materials.

Over 40 An

accumulated t o t a l of approximately 450,000 h r of o p e r a t i o n i n c o r r o s i o n t e s t i n g l o o p s and o t h e r high-temperature pumping a p p l i c a t i o n s h a s demonstrated t h e i r r e l i a b i l i t ~ r . ~ ~ As shown i n F i g .

6, t h e pump h a s an over-

h x r ~v e r t i c a l s h a f t with an o i l - l u b r i c a t e d f a c e seal above t h e l i q u i d

UNCLASSIFIED ORNL-LR-DWG 3095A

2 in.

LIQUID

IMPELL

11 t

l e v e l i n a n i n e r t - g a s atmosphere.

Cooling of t h e s h a f t and seal i s p r o -

vided by a flow of o i l down through t h e hollow s h a f t and o u t p a s t t h e The i n l e t t o t h e pump i s l o c a t e d on t h e s i d e , and t h e o u t l e t i s

seal.

a t t h e bottom.

%e p e r f o r m a x e c h a r a c t e r i s t i c s of t h e pump f o r v a r i o u s

pump speeds are g i v e n i n F i g .

A pump speed of approximately 3000 rpm

i s used f o r most long-teim o p e r a t i o n . T!e c e n t , r i f u g a l p u q ) i s d r i v e n through dou5le V-belts b y a v a r i a b l e speid magnetic c l u t c h and a

5 hp motor.

The speed i s r e g u l a t e d by an

e l e c t r o n i c c o n t r o l supplying d-c t o t h e magnetic-clutch u n i t .

I n order

t o decrease t h e p o s s i b i l i t y of a flow stoppage as a r e s u l t of an

e l e c t r o n i c u n i t f a i l u r e , a n a u x i l i a r y d-c source i s s u p p l i e d f o r t h e magretic c l u t c h , which is p r e s e t a t t h e d e s i r e d speed. supply c i r c u i t i s shown s c h e m a t i c a l l y i n F i g .

This c l u t c h

Relay SR-3 a u t o m a t i c a l l y

changes over t o t h e a u x i 1 i a . r ~supply i f any p e r t u r b a t i o n of t h e normal control occurs.

The o p e r a t i o n of t h e pump i s thelz maintained by t h e

a u x i l i a r y - c l u t c h supply, while e l e c t r o n i c t u b e s are changed o r o t h e r r e p a i r s are b e i n g made t o t h e normal supply.

I n t h e e v e n t of t h e f a i l u r e

of both c l u t c h s u p p l i e s o r a motor f a i l u r e , s t e p s are t a k e n a u t o m a t i c a l l y t o p r o v i d e h e a t t o t h e e n t i r e loop, as w i l l be d i s c u s s e d f u r t h e r i n t h e following s e c t i o n on alarm and a u t o m a t i c - a c t i o n c o n t r o l s . Since t h e pump c o n t a i n s t h e only g a s - l i q u i d i n t e r f a c e of t h e system, a sampling device6 and l e v e l i n d i c a t o r s are mounted on t h e pump bowl flange.

The maximum and minimum l i q u i d l e v e l s are i n d i c a t e d by a spark-

plug-type probe which l i g h t s an i n d i c a t o r as t h e molten s a l t comes i n

c o n t a c t w i t h it. A c r o s s - s e c t i o n a l view of t h e sampling device i s shown i n Fig.

It c o n s i s t s of a dynamic-seal and b a l l - p l u g - v a l v e arrangement through which a d i p tEbe can be i n s e r t e d i n t o t h e molten s a l t and a sample withdrawn without contaminating t h e i n e r t - g a s covering t h e l i q u i d i n t h e pump bowl.

The samples, which are removed p e r i o d i c a l l y f o r chemical a n a l y s i s ,

i n d i c a t e t h e t y p e and rate of i n c r e a s e of v a r i o u s c o r r o s i o n p r o d u c t s i n t h e molten s a l t . I n p r e p a r a t i o n f o r t a k i n g a sample, a seal i s e s t a b l i s h e d around t h e p e r i p h e r y of t h e sample tube, and t h e i n e r t g a s i s i n t r o d u c e d t o purge U ? .

t h e v o l m e between t h i s seal and t h e b a l l p l u g v a l v e below.

The b a l l

r A-C PUMP MOTOR CIRCUIT POTENTIAL OPENS ON CLUTCH LOW SPEED

PYROMETEQ

IPENS ON LOSS OF CLUTCH ORMAL SUPPLY

M A I N RESISTANCE HEATER Y T E N T I A L

-7

63 MAIN RESISTANCE HEATER POTENTIAL

OPENS ON

SRI-4 TEMPERATURE

I=@=

BYPASS OPEN ON OPERATE CLOSED ON LOW TEMPERATURE

TACHOMETER CIRCUIT

FOR BLOWER MOTOR 4

L - S U P P L Y

CLOSED ON TEST

TRANSFORMER TAP

(TIME DELAY

DAMPER CONTROL

"OFF"

OPENS O N LOOP HIGH TEMPERATURE AMPLIFIER

AUXILIARY CONTROLS

CLOSED AT STARTUP OF OPERATION TO ALLOW PICKUP OF RB. OPEN AFTER STARTUP-

MAIN RESISTANCE HEATER CIRCUIT

OPEN ON PREHEAT CLOSED ON OPERATE 52T

OPEN ON RESET AN0 PREHEAT CLOSEO ON OPERATE

MAIN RESISTANCE HEATERS CONTROL

-it--',

r-OPEN ON RESET :LOSE0 ON OPERATE

CLOSES O N

LOW CLOSES TEMPERATURE ON LOOP

S U B STA. AND DIESEL CKT. POT.

/;;;;\

L'g?'

AUTOMATIC OPERATION

MAIN SUPPLY COOLER RESISTANCE HEATER

Re-6 SIMPLYTROL PYROMETER H E T E Q RELAV

CLOSEO ON PREHEAT OPEN ON OPERATE-

TACHOMETER SPEED AND LOW TEMPERATURE CONTROL

fyw

40 KVA TRANSFORMER

0-50" AC

COOLER

c L u r c n AUXILIARY SUPPLY

OPEN ON LOSS

0-c

RECTIFIER

I20 Y AC V A R I A C

COOLER PREHEAT CONTROL

0 0-100

SELECTOR SWITCH DEVELOPMENT CLUTCH CONTROL CIRCUIT

I CLUTCH S N UPPL O V-I PARTIAL CLUTCH SUPPLY CONTROL CIRCUIT

F i g . 7.

E l e c t r i c a l Schematic of Automatic Action Relays.

UNCLASSIFIED ORNL-LR-DWG 65062

REMOVABLE HEAD ASS E MB LY

RMANENT LOOP UNTED ASSEMBLY

- -MAXIMUM - -- - -_ LIQUID LEVEL - -- - - - - MINIMUM LIQUID LEVEL

Fig. 8. Cross Section of a Molten-Salt Saqling Device.

14 p l u g v a l v e i s t h e n opened, and t h e d i p t u b e i s i n s e r t e d i n t o t h e molten salt i n the pmp.

A vacuum i s t h e n a p p l i e d t o t h e d i p tube, and t h e

sample i s drawn ap i n t o t h e t u b e . b a L plug valve c l o s e d .

The d i p t u b e i s withdrawn, and t h e

Th? nznber of samplzs is l i m i t , &

only by t h e

axount of n o l t e n s a l t whtch car, be removed withot1.t deprimicg t h e pump. E l ' , ,

..LLJ

fiow of molter- saLt from t'ne pmip i s past t h e d r a i c - t a n k

c o x e c t i o n , tlzrough t h e f i r s t h e a t e r s e c t i o n , tkroJgh a lorig-raaius

182-dSg Surd,

t h r o g h C,ke second h z a t e r see-cion, through a c o i l e d

cooler, and back t o t h t pdmp.

The c o o l e r s e c t i o n i s a h e l i c a l c o i l

yioc:r?ted i n a c i r c u l a r - & L c t a m u i u s through whicn arn'cient a i r i s blown.

To provide t a e r x c z s s s r y p r e h e a t t a n p e r a t u r e f o r f i l l i n g t h e l o o p and f o r p r o t e c t l o n a g a i n s t s o l i d i f i c z t i o n of t h e m o l t e r s a l t i c a n emergency s i t u a t i o i , t h e c o o l e r c o i l i s provided idith e l e c t r i c a l h e a t i n g l u g s a t b o t h ends and i n t h e c e n t e r f o r e l e c t r i c a l - r e s i s t a n c e h e a t i n g .

The i n l e t

a_rd o d t l e t & r e k e p t e t t5.e s a ~ ep o t e n t i a l e l e c t r i c a l l y t o c o n f i n e t h e flow of ca-rerrt t o tke c o o h r c o i l oLnly. A s e p a r a t e 10-kva s a t u r a b l e c o r e r e s c t o r a r d t r a r i s f o r w r are connected t o t h e c o o l e r c o i l f o r use i n p r e h e a t i n g c r d x i p g a n esnergeacy alarm conditior,.

Tke c o n t r o l i s s e t

a t a predeteLrmined rate of approximately 300 axp arid

15 vg and t h e power

i s applied agtomatically m e n required,

Other a u x i l i a r y eq".ipment r e q u i r e d f o r t h e o p e r s t i o n of t h e l o o p i x h d e a 3000 cfrr. blower, a c o o l i n g o i l suppiy, an3 t h e necessary u t i l -

i t i e s , sdch as c o o l i 2 g aZr f o r t h e frozen-plug vaivz, i n e r t gas, and c o o l i n g watcr.

The e z t i r e p~urp, loop, and d r a i n t a n k assembly i s shown

i n F i g . 3 mourited on z n o b i l e 3011y f o r e a s e of f a b r i c a t i o n , i n s p e c t i o n , and 5 n s t a L a t i o n .

T2e d s l l y c o n t a i n s one h a l f of t h e i n s u l a t e d c o o l e r

duct a?d t h e a i r d e f l e c t o r i n t h e c e n t e r , which f o r m a n a n n u l a r a i r passage.

Tke back h a l f of t h e c o o l e r d u c t i s momted on t h e permanent

s t a n d f r a z e , which also c o n t a i n s t h e c i r c u l a t i n g c o o l i n g o i l system, h e a t e r concections, and t h e pump-drive motor.

Mounted over t h e c o o l e r

d u c t i s as i n s u l a t e d cover l i d t h a t i s h e l d i n ar? u p r i g h t p o s i t i o n by a solenoid-3eid i a t c h during o p e r a t i o n of the! l o o p .

I n t h e e v e n t of an

a l a r n co%Xtioz which sl?v.ts o f f t h e blower motor, t h e l a t c h i s r e l e a s e d OK

t'ne drop l i d azd e r x l o s e s t h e c o o l e r c o i l t o p r e v e n t e x c e s s i v e l o s s

of t e a t .

15 A l l c r i t i c a l l o o p welding i s done by t h e H e l i a r c p r o c e s s w i t h i n e r t cover g a s and backup purge according t o a s t r i c t welding s p e c i f i c a t i o n . 7 A l l welds a r e i n s p e c t e d v i s u a l l y , by dye p e n e t r a n t , and by x-ray.

Mter

welding, t h e l o o p i s instrumented with Chromel-Alumel thermocouples and heaters.

The thermocoiip1.e~are s p o t welded t o t h e t x b i n g and covered

with shim s t o c k f o r p r o t e c t i o n .

Both ceramic- and sheath-type h e a t e r s

are used f o r h e a t i n g such a u x i l i a r i e s as t h e d r a i n tank, t h e pump bowl, t h e h e a t e r l u g s , acd t h e f r e e z e - p l u g v a l v e . 4

on t h e l o o p p i p i n g f o r emergency use only i n t h e event of a f a i l u r e of t h e main power supply.

Standby h e a t e r s are mounted

After t h e h e a t e r s and thermocouples are a t t a c h e d ,

t h e l o o p i s covered w i t h 3 i n . of high-temperature i n s u l a t i o n .

The l o o p

and d o l l y assembly are t k e n i n s t a l l e d i n t h e f a c i l i t y , and t h e connections are made t o c o n t r o l s and power s u p p l i e s .

Alarm and Automatic-Action Controls The system thermal i n e r t i a i s low because of t h e small-diameter t u b i n g used, and t h e r e f o r e safeguards must be provided t o p r e v e n t s o l i d i f i c a t i o n of t h e s a l t i n t h e l o o p .

The s a l t i n t h e c o o l e r c o i l w i l l become

s o l i d i n l e s s t h a n 1 min i f t h e flow i s stopped and no e x t e r n a l h e a t i s applied.

An alarm a n 5 a u t o m a t i c - a c t i o n r e l a y system w a s designed t o p r o -

t e c t t h e loop even though t h e r e w a s a f a i l u r e of t h e power source or any one p i e c e of o p e r a t i n g equipment. The b a s i c o u t l i n e of t h i s system i s shown i n block form i n F i g . Any one of t h e alarms shown a t t h e t o p of F i g .

9, i.e., any c o n d i t i o n

which w i l l cause flow stoppage o r adverse temperatures, w i l l a u t o m a t i c a l l y p l a c e t h e l o o p i n a n i s o t h e r m a l or safe c o n d i t i o n by performing t h e a c t i o n s l i s t e d a t t h e bottom of t h e f i g u r e .

This r e s u l t s i n t h e e n t i r e

l o o p b e i n g warmed and i n a safe or i s o t h e r m a l c o n d i t i o n while t h e n e c e s s a r y a c t i o n i s t a k e n t o r e s t o r e t h e equipment t o o p e r a t i n g c o n d i t i o n .

To cover t h e p o s s i b i l i t y of t h e f a i l u r e of t h e main power transformer, t h e ceramic standby h e a t e r s are connected a f t e r 2 see, and t h e y w i l l m a i n t a i n i s o t h e r m a l c o n d i t i o n s u n t i l t h e main source of power i s r e s t o r e d . A l l r e l a y a c t i o n s i n d i c a t e d i n t h e b l o c k diagram of F i g . s c h e m a t i c a l l y i n F i g . 7.

The battery-powered r e l a y

by r e l a y R-4 t o perform t h e

f0b.r

R-8

9 are shown i s de-energized

Pdnctions which p l a c e t h e l o o p on

LOSS OF NORMAL AND AUXILIARY CLUTCH SUPPLIES (PUMP STOPS)

LOSS OF PUMP MOTOR (PUMP STOPS)

LOOP LOW TEMPERATURE

I I

INSTANTANEOUS ALARM-ACTION RELAY (NO DELAY IF CONTROL POWER IS AVAILABLE 1

LOSS OF MAIN POWER SUPPLY TO HEATER SECTION

LOOP HIGH TEMPERATURE

TIME-DELAY ALARM-ACTION RELAY (2sec DELAY IF CONTROL POWER NOT AVAILABLE TO ALLOW FOR AUTOMATIC THROWOVER FROM NORMAL TO ALTERNATE FEEDER 1

CONNECTS POWER TO EMERGENCY HEATERS ON LOOP PIPING AT PRESET RATE

I -

DROPS LID ON COOLER BOX

SWITCHES MAIN POWER SUPPLY FROM OPERATE TO PREHEAT CONNECTIONS ON LOOP

Fig. 9.

CONNECTS POWER TO COOLER COIL AT PRESET RATE

Block Diagram of Automatic A l a r m Actions.

17 isothermal operation. To guard a g a i n s t t h e f a i l u r e of t h e power supply t o the b u i l d i n g which houses t h e t e s t s or t o t h e bus d u c t supplying power t o t h e loops, equipmect h a s been designed and i n s t a l l e d as shown i n b l o c k diagram i n F i g . 10.

Should a f a i l u i - e occur of t h e normal b u i l d i n g feeder, a t r a n s f e r

t o a n altercate f e e d e r i s made a u t o m a t i c a l l y w i t h i n 2 see.

The time-delay

r e l z y TD-1 and r e l a y R-3 of F i g . 7 w i l l h o l d i n t h e battery-powered r e l a y

E-6, allowing t h e traisfer t o be made without d i s t u r b i n g t h e o p e r a t i o n of the loops.

Should t h e biiilding e l e c t r i c a l power be u n a v a i l a b l e f o r a

p e r i o d l o c g e r thap 2 see, t h e emergency d i e s e l g e n e r a t o r , which s t a r t e d imnediately, would b e g i n assuming t h e l o a d through a s e q u e n t i a l timer. Loads would b e picked i3.p a l t e r n a t e l y between motor s t a r t u p and h e a t e r l o a d u n t i l t h e e n t i r e f a c i l i t y of 15 l o o p s had power r e a p p l i e d w i t h i n 40 s e e after the interruption.

The 300-kw c a p a c i t y of t h e d i e s e l g e n e r a t o r i s

s u f f i c i e n t t o o p e r a t e t h e l o o p s i s o t h e r m a l l y u n t i l normal b u i l d i n g e l e c t r i c a l power i s a g a i n available. Other alarms a r e a v a i l a b l e f o r t h e p r o t e c t i o n of t h e l o o p s t h a t g i v e only a n a u d i b l e o r v i s u a l s i g n a l or both f o r c o r r e c t i v e a c t i o n t o b e t a k e n by t h e o p e r a t o r .

These alarms i n c l u d e l o s s of blower motor, low

c o o l i n g o i l flow, l o s s ofâ&#x20AC;&#x2122; c o o l e r p r e h e a t p o t e n t i a l , improper p o s i t i o n of c o n t r o l switches, improper p o s i t i o n of alarm acknowledge switches, and

loss of c o n t r o l c i r c u i t p o t e n t i a l . Operation and Maintenance of a T e s t Loop The s t a r t u p of a new c o r r o s i o n t e s t i n g l o o p i s preceded by a s e r i e s of checkouts of equipment..

When a l l t h e e l e c t r i c a l , thermocouple and

c o n t r o l c i r c u i t s are t e s t e d s a t i s f a c t o r i l y and t h e l o o p i s l e a k t i g h t , t h e e n t i r e l o o p i s p r e h e a t e d t o llOOÂ°F w i t h t h e pump s h a f t r o t a t i n g slowly and t h e c o o l i n g o i l c i r c d a t i n g .

The s a l t mixture chosen f o r t h e p a r t i c -

u l a r t e s t i s i n t r o d w e d i n t o t h e d r a i n t a n k i n a molten s t a t e a t a s l i g h t l y h i g h e r t e m p e r a t m e t h a n t h a t of t h e l o o p .

The d r a i n t a n k l e v e l

probe i n d i c a t e s when t h e r e i s s u f f i c i e n t s a l t t o f i l l t h e l o o p .

Inert

g a s pressv-re i s admitted t o t h e d r a i n t a n k and vented from t h e upper p o r t i o n of t h e l o o p a t t k e p m p .

UNCLASSIFIED ORNL-LR-DWG 65069

NORMAL BUILDING FEEDER

ALT E R NAT E BUILDING FEEDER

DIESEL G ENE R AT0 R STARTS WHEN POWER FAILS

AUXILIARY BUILDING FEEDER

MANUAL SWITCHING EQUIPMENT

I SEQUENTIAL TIMER FOR INCREMENTAL APPLICATION OF LOAD

I AUTOMATIC SWITCHING ,

BUS CUCT

SUB STATION

SUPPLYING POWER TO EQUIPMENT AND CONTROLS FOR 15 LOOPS

SUPPLYING Iio-kva TRANSFORMER POWER FOR i5 LOOPS

F i g . 10.

Block Diagram of Building Electrical Supply.

A s t h e s a l t i s slow.ly f o r c e d up i n t o t h e loop, i t s p a t h can be t r a c e d by t h e temperature r e a d i n g s of thermocouples p l a c e d along t h e tubing.

Level probes i n t h e pump i n d i c a t e when t h e l o o p i s f u l l , and

t h i s l e v e l i s maintained by manipulation of gas p r e s s u r e while c o o l i n g a i r i s supplied t o t h e freeze-plug valve.

When t h e temperature of t h e

v a l v e i n d i c a t e s a s o l i d plug, t h e p r e s s u r e i s r e l e a s e d from t h e d r a i n t a n k and t h e pump speed :is i n c r e a s e d t o b e g i n c i r c u l a t i o n of t h e molten

salt.

Power from t h e mafin t r a n s f o r m e r i s a d j u s t e d t o m a i n t a i n t h e

d e s i r e d temperature leve:-.

The f i r s t l o a d of s a l t i s c i r c u l a t e d f o r a

minimum of 2 h r t o c l e a n t h e system and i s t h e n dumped i n t o t h e d r a i n t a n k and removed.

The f 3 l i n g o p e r a t i o n i s r e p e a t e d w i t h t h e supply

of s a l t t o be used f o r t h e c o r r o s i o n t e s t . When t h e t e s t s a l t is c i r c u l a t i n g , t h e d i f f e r e n t i a l temperatures are e s t a b l i s h e d by s h u t t i n g o f f t h e c o o l e r heat,

opening t h e l i d on t h e

c o o l e r duct, t u r n i n g on t,he blower, c l o s i n g t h e 1 6 0 0 - ~ ph e a t e r s e c t i o n b r e a k e r (which connects all f o u r h e a t e r l u g s ) , and a d j u s t i n g pump speed, c o o l i n g a i r flow, and main t r a n s f o r m e r power, as r e q u i r e d .

When t h e

d e s i r e d c o n d i t i o n s are met, a l l t h e c o n t r o l l e r s , alarm s e t p o i n t s , and automatic f u n c t i o n i n g r e l a y s are s e t f o r continuous o p e r a t i o n . I n o r d e r t o assure, as far as p r a c t i c a l , t h a t a l l emergency equipment w i l l f u n c t i o n p r o p e r l y when t h e need arises, a p r e v e n t i v e maintenance program i s c a r r i e d o u t weekly.

A check l i s t i s completed f o r each

f a c i l i t y which c a l l s f o r t h e t e s t i n g of a l l important alarms, t h e throwover c i r c u i t on t h e a u x i l i a r y c l u t c h supply, t h e cooler drop l i d , and

t h e c l u t c h brushes; a v i s u a l i n s p e c t i o n i s made of t h e system. The t e s t s under t h i s program have been o p e r a t e d with maximum w a l l t e m p e r a t u r e s of 1200 t o 1500째F, a temperature d i f f e r e n c e between t h e 0

maximum w a l l temperature and t h e m i n i m u m f l u i d temperature of 200 F, and flow rates up t o 3 gpm.

P r e v i o u s l y t e s t s were conducted w i t h w a l l t e m -

p e r a t u r e s of 1500째F and h i g h e r . 8

The w a l l t e m p e r a t u r e s o b t a i n e d are

l i m i t e d only by t h e s t r e n g t h o f t h e c o n t a i n e r material used.

The tem-

p e r a t u r e d i f f e r e n t i a l o b t a i n e d i s l i m i t e d b y t h e flow rate and power available.

The f o r c e d - c i r c u l a t i o n c o r r o s i o n t e s t f a c i l i t y with e l e v e n

t e s t s t a n d s showing i n t h e l e f t background i s p i c t u r e d i n F i g . 11. The U

remaining f o u r t e s t s t a n d s are on t h e o p p o s i t e s i d e of t h e a i s l e t o t h e right.

21 I

Summary

Twenty-five l o o p s hsve been f a b r i c a t e d with both INOR-8and Incone19 and have o p e r a t e d under t h i s program f o r a n accumulated t o t a l of over 29O,OOO h r .

Twenty of t h e loops, t h i r t e e n of which were f a b r i c a t e d of

INOR-8and seven of Inconel, operated from one t o two and a h a l f y e a r s b e f o r e b e i n g t e r m i n a t e d 2nd examined m e t a l l o g r a p h i c a l l y . The long-term o p e r a t i o n and metallographic examination of t h e s e l o o p s w a s i n s t r u m e n t a l i n t h e acceptance of

INOR-8as t h e c o n t a i n e r

material f o r t h e Molten ;Salt Reactor Experiment.lo

The expected c o r r o s i o n

i s expected t o be l e s s t h a n 1 m i l s / y r a t t h e d e s i g n o p e r a t i n g temperature

of 1225'F. Corrosion specimen weight loss and s a l t sample d a t a from t h e s e l o o p s i n d i c a t e d t h a t t h e primary c o r r o s i o n product i s chromium and t h a t a n e s s e n t i a l l y c o n s t a n t v a l u e w a s achieved a f t e r approximately 5000 h r of operation.ll Acknowledgments Many persons have made important c o n t r i b u t i o n s t o t h e d e s i g n and o p e r a t i o n of t h e s e f a c i l i t i e s .

Acknowledgment i s made e s p e c i a l l y t o

H. W. Savage under whose d i r e c t i o n t h i s program w a s executed.

The suc-

c e s s f u l o p e r a t i o n of t h e s e l o o p s w a s due t o a l a r g e e x t e n t t o W. H. Duckworth and t h e s h i f t o p e r a t i o n s group under R. Helton, and t o

many o t h e r s t o o numerous t o mention.

R e f e r e ne e s

1. J . H . &Van and J. D. Man y, Corrosion P r o p e r t i e s of Fused-Fluoride S a l t Mixtures, Trans. Am. Nuclear Soc., 2.

(1):44 (June 1958).

D. E. Trauger a i d J . A. CorLLin, CircLllat.ing Bused-Salt-Fuel l r r a d l a t i o n T e s t Loop, Trans. Am. Nuclear Soc., 2 (1):173-4 (CTi;.De

1959).

3 " 5. ?. B i a k e l y , Molten S e l t Coxpositions, Oak 3idge National Laboratory Report C F - 5 8 - 6 - m J u n e 1 2 ,

1958).

J . 3. Keyes and A. I . Krakoviak, High-Frequency Surface Thermal F a t 1 Trans. Am. NLlclear Soc., r l ) : 2 2 - & (June 1959).

W. F. Boudre~~i.,A, 5. G r i ~ d ~ 2 . and L H. W. Savage, Tlze Development and Operation of Cantrifug8.l P w p s f o r Liquid Metals 2nd Fused S a l t s a t l100-150G째F, Trans. AT. Nuclear Soc 2 (1):l7-l.8 (June 1959).

W. B. McDonald a i d J . L. Crowley, A Samplin Device f o r Molten S a l t Systems, Oak Ridge R a t i o n a l Laboratory Report \8 ORNL-2 (March 7,1960)

'i' 3. . Housley apd 2 . P a t r i a r c a ,

Procedure S p e c i f i c a t i o L PS-2 f o r

D.C. AFX Weifiins of l n c o n e l Tubing f o r Higk! Corrosion 4-pplications, I

Oak Ridge E a t i o n s 1 Lcboratory.

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J . A. Lane, ?. G . bkcPhersori and F. Maslar?, F l u i d Fuel Reactors, p . 596, Addisoi-We.cle;r, Reading, Mass., 1 9 5 8 7

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