- , 4

O A K RIDGE NATIONAL LABORATORY operated by

UNION CARBIDE CORPORATION for the

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

ORNL- TM- 528 -~. -..

DESIGN AND 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 to revision or correction ond therefore does not represent a final report. The information i s not to be abstracted, reprinted or otherwise given public dis- semination without the approval of the ORNL patent bronch, Legal and Infor- mation Control Department.

I

LEGAL NOTICE

Th is 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 th rmspoct to the accuracy,

completeness, or usefulness of the information contained i n th is report, or that the use of

any information. apparatus, method, or process disclosed i n th i s report moy not infr inge

pr ivate ly owned r ights; or

6. Assumes ony l i ob i l i t i es w i th respect t o the use of, or for domoger resul t ing from the use of

any information, apparatus, method, or process disclosed i n th i s report.

As used i n the obove, "person act ing on beholf o f the Commission" includes any employee or

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

or controctor of the Commission, w employee of such controctor prepares, dinseminotes. or

provides access to, ony informotion pursuont to h i s employment or controct w i th the Commission,

or h i s employment w i th such controctor.

' ...

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 the U . S . ATOMIC ENEBGY COMMISSION

ORNL-TM-528

h

t iii

CONTENTS

Ab s t r a c t

In t roduc t ion

Descr ipt ion of Test Loop and Auxil iary Equipment

Alarm and Automatic-Action Controls

Operation and Maintenance of a T e s t Loop

Summary

Acknowledgments

Page

1

1

2

1 5

17

21

21

7

.

DESIGN AND OPERATION OF FORCED-CIRCULATION

CORROSION TESTING LOOPS WITH MOLTEN SALT

.

J. L. Crowley W . B. McDonald D. L . Clark

Ab s t r ac t

StandardLzed t e s t f a c i l i t i e s were developed and oper- ated f o r i n v e s t i g a t i n g t h e compat ib i l i ty of s t r u c t u r a l materials and flowing molten f l u o r i d e salts . The s tandard loop accommodates var ious 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 fe ren t ia l s and permits 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 quan t i ty f o r c o s t reduct ion . The t e s t loop c o n s i s t s of a pump, two heated sec t ions , a cooled sec t ion , a d r a i n tank, and a frozen- plug-type valve. Automatic con t ro l s and equipment were developed t o prevent s o l i d i f i c a t i o n of t h e sal t mixtures (m.p., 800 t o 1100°F) i n the 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 they operate with 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 sa l t flow rate of up t o 3 gpm. Twenty-five t e s t loops have been operated f o r an accumu- l a t e d operat ing time-- of Z90,OOO h r . been operated continuously f o r more

Ind iv idua l 1 oops have than one yea r .

In t roduct ion

Mixtures of molten f l u o r i d e salts have been inves t iga t ed ex tens ive ly

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 transfer

media.

conta iner a l l o y i s detemnined, i n p a r t , by t es t s with thermal-convection

loops,’ and t h e most promising combinations of sa l t mixtures and

s t r u c t u r a l material are i;hen s tud ied i n fo rced -c i r cu la t ion cor ros ion

t e s t loops . These loops simulate a l l e s s e n t i a l r e a c t o r opera t ing con-

d i t i o n s except r a d i a t i o n m 2

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 t ime.

The compat ib i l i ty of a p a r t i c u l a r salt mixture with a proposed

The t e s t s tands and loops have been s tandard-

Many mixtures of mo:lten salts have been t e s t e d . The bas 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 thium, beryll ium,

t

2

z i r c o n i m , thori,Jm, ar2d uracium i n va r ious p ropor t i cns t h a t g ive melt ing

temperatures gene ra l ly f a l l i n g i n t3e 800 t o llOO0F range.

and d e n s i t y vary with each mixture.

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

ct:r:t.ipoLse en? E sp~.cZZj_c gya:iity of 2 . 4 et I I C O F. c orz~.:riFng k e r y L l i z - e q d re s t z i n g e c t saf z t ; ~ p-scaut,ions t.0 prevent ex-

posure of p e r s o x e l t o t -2 -L~ t o x i c nateriai .

V i scos i ty

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

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

T'-p sal t mixtures . I

rn p r e d i c t ecc:?.retelg co r ros ion r a t e s f o r power r eac to r s , t h e t e s t s

r m s t necessa r i ly be of long-term ciuratioi?. Tl.e t z s t sts~zci c o n t r o l

s p t m w z s t?ie:mefcr? ciesigced not only t o m & i E t & i c .the necessary t e s t

co_rditions for i o ~ g per iods 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 scl i2ff isatLon cf t h e sai t i n t3e system. S i m e

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

melt ing 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 loop.

The tes t l cop i s I l l s s t re t ,ed i n Fig. 1. m, J.LY loop c o e s i s t s of a

punp,, two heatzd sectioris, 8 cooled sect.ion, a ?.rc,ic t.a;-k, and a f rozen-

plug-type -;sive. . A l l w e t k d p a r t s of t h e ioop are fa-9r icated of t h e

a l l o y be icg s tud ied . Loop tubirg s i z e i s s e l e c t e d t o provide t h e proper

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 ~ c e h e a t i n g and t o g ive a p res su re drop

a t design 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 . A flow

d i a s r m 52' t:?? IYZ~- -LSE-S~ . - + c i r cu2z and t h e a a x i l i e r y co.ntrols f o r t h e

- fi1er-t COITF;:~ 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 expe r i e ixe gaiced i r ?

zaxy tes 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 w r a t e s , a temperttu:?e g r e d i e s t s de s i res- Such s t anda rd i z a t i on

has permit ted f 'ehricr, t ion of components i n quan t i ty f o r both c o s t re-

dimction ar_? eese zjf a.ese%bly-o

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 8 ?xLrlim.m of dowr? the.

o.d. , O.C45-in.-wall -Lg.-oiii?g has been fcund t o 3e su5 tab le .

--

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 loops

F o r x o s t tests, O.5-in. -

. I

1

I

‘ l c ,

UNCLASSIFIED ORNL-LR-DWG 64740

110kva -:r POWER SUPPLY

/

1600-amp BREAKER

-~“B” AA ,

(0 kva POWER SUPPLY

Fig. 1. Molten-Salt Corrosion Testing Loop and Power Supplies.

Unclassified Photo 34533

MAGNETIC CLUTCH 8 5HP

, ' > SHAFT AN0 SEAL OIL -

FLOW ALAR

COOLING WATER

SUPPLY

HELIUM SUPPLY

L

,,:;,"ZE ;LVE\

AIR

p F

I I I 1

DRAIN TANK

AIR VENT

EQUIPMENT IDENTIFICATION

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 INDICATOR SC-SPEED CONTROL LL-LEVEL LIGHT

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

+CHECK VALVE (XV)

Fig . 2 . Flow Diagram of Molten S a l t Loop and Ut i l i t i e s .

!

5

i

Unclassified

Fig. 3. Photograph of Molten-Salt Corrosion Testing Loop on Mobile Dolly.

6

The flow rate, Reynolds number, p re s su re drop, and power required

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 phys ica l p r o p e r t i e s

of t h e p a r t i c u l a r sa 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 res su re drop ( f ee t of head) vs flow (gpm) curve i s determined

by m i n g t h e phys ica l p r o p e r t i e s of t h e molten salt t o be t e s t e d and t h e

geometry of t h e l o o p . Ey superimposing t h i s c m v e on t h e pump operat ing

c h a r a c t e r i s t i c curve, as shown i n F ig . 4, t h e d e s i r e d flow r a t e i s

determined wi th in t h e Lirr i ta t ions 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 sal t i s enough h ighe r t h a n

t h a t of t h e metal con ta ine r w a l l s t h a t it can be neglected i n determining

t h e power requiremects of t h e hea-cer s e c t i o n s . The t ransformer vo l t age

r equ i r ed f o r t h e p a r t i c u l a r salt mixture shown i n Pig. 4 w a s c a l c u l a t e d

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 equ i r ed of t h e t ransformer w a s 58.8 Kw a t 1250 amp and 47.2 v o l t s . The

two h e a t e r s ec t ions , 96 i n . and lo9 i n . i n length, 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 665 and 585 amp, respec-

t i v e l y .

imparts a higher h e a t f l c x where t h e bu lk f l u i d temperature i s t h e

lowest .

ternperatires a t t h e o u t l e t of bo th h e a t e r s . A w a l l temperature and bulk

f l u i d t e n p e r a t z r e p r o t i l e of E. t y p i c a l loop while i n ope ra t ion a t t e s t c o a d i t i o l s i s sho~n Zr Fig . 5. 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 l operation, t o e l imina te

ho 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 tub ing bends.

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 loop t h a t

wo-dd be necessary t o ob ta in t t e d e s i r e d f l u i d temperature with one con-

t i n c o u s h e a t e r s e c t i o n . The flow of 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 operat ion a t t e s t cond i t ions by t h e nethod of attachment

t o t h e t ransformer. O x t e rmina l of t h e t ransformer 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 rs t h e a t e r

s e c t i o n . 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 the r t ransformer t e rmina l .

loop i s grouEde3 a t t k pimp, whlie t h e renainder of t h e loop i s

The s h o r t e r f irst s e c t i o n (96 i n . ) has l e s s r e s i s t a n c e and

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

The 12R hea t ing i s app l i ed only t o

Two

The

c -

it

P

.

U N C L A SS IF1 ED ORNL- LR-DWG 65065

110 - I I 1 I I

100

90

80

70 A

c + Y

60 0

W I a

a 50 5 a

40

30

20

10

0 0 1 2 3 4 5 6 7 8

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.

1300

1250

c 1200 LL v

i150 l-

[L

a

a w (100

I- 4050 5

to00

950

UNCLASSIFIED ORNL-LR-DWG 65066

0 400 200 300 400 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 in su la t ed .

A t tes t condi t ions, from 350 t o TOO amp of 60-cycle a l t e r n a t i n g

cu r ren t flows i n each h e a t e r s ec t ion 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 suppl ied t o t h e h e a t e r s ec t ions through a n icke l

lxg welded t o a thick-walled adapter s e c t i o n of t h e loop.

'I3e power f o r t h e h e a t e r sect ior , i s scppi ied by a 110-kva t r a n s -

f omer kaving a low-voltsge high-current secondary winding, with a

sa turable-core r e a c t o r on t h e primary s ide .

pyrometer r egu la t e s t h e 3-c vol tage t o t h e sa tu rab le r e a c t o r and de te r -

n ines t h e vol tage appl ied t o t h e h e a t e r s ec t ion of t h e loop by t h e main

power t ransformer.

h e a t e r s ec t ion i s l i m i t e 3 by a maximum-adjustment rheos t a t t h a t l i m i t s

t h e d i r e c t cu r ren t ava i lcable t o t h e sa tu rab le r eac to r .

A propor t iona l -cont ro l

The mount of power which may be appl ied t o t h e

A loop high-temperature alarm i s designed t o c u t of f t h e d i r e c t

cu r ren t t o t h e sa tu rab le r e a c t o r and t o reduce t h e power t o a minimum

leakage value. When t h e loop temperature again drops below t h e alarm

set poin t , t h e automatic a c t i o n r e l a y i s reset and t h e power i s re-

appl ied a t t h e rate previously se t . The high-temperature alarm thus

serves as an "on-off" c o Q t r o l of t h e power i f an emergency condi t ion

occurs.

The t ransformer i s connected t o t h e loop hea te r l u g s by a 5OO,OOO-

c i r c u l a r - m i l l s cab le through a 1600-amp breaker .

t h e connections of t h e h e a t e r s ec t ion are such t h a t t h e cu r ren t f low i s

confined t o t h e two h e a t e r s ec t ions (4 connections t o t h e loop) .

ever, when it i s necessa:ry t o prehea t o r provide emergency hea t ing t o

the e n t i r e loop, t h e 1600-amp breaker shown i n Fig. 1 i s t r ipped , leav ing

only two connections t o t h e loop.

cep t ion of t h e cooler c o i l , i s heated by t h e formation of two p a r a l l e l

pa ths of nea r ly equal r e s i s t a n c e .

During normal opera t ion

How-

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

A downflow cen t r i fuga l sump pump designed a t ORNL i s used.

of t hese p u ~ p s have been f a b r i c a t e d of fou r d i f f e r e n t materials. An

accumulated t o t a l of approximately 450,000 h r of operat ion i n cor ros ion

t e s t i n g loops and o the r high-temperature pumping app l i ca t ions has demon-

strated t h e i r r e l i a b i l i t ~ r . ~ ~ As shown i n F ig . 6, t h e pump has 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 ace seal above t h e l i q u i d

Over 40

10

UNCLASSIFIED ORNL-LR-DWG 3095A

LIQUID

I M PELL

-

2 in.

n.

11

I

t

W

.

I

U

?.

l e v e l i n an i n e r t - g a s atmosphere. Cooling of t h e s h a f t and seal i s pro-

vided by a flow of o i l down through t h e hollow s h a f t and out p a s t t h e

seal. The i n l e t t o t h e pump i s loca ted on t h e s ide, and t h e o u t l e t i s

a t t h e bottom. %e pe r fo rmaxe c h a r a c t e r i s t i c s of t h e pump f o r var ious

pump speeds are given i n Fig. 4. i s used f o r most long-teim opera t ion .

A pump speed of approximately 3000 rpm

T!e cent , r i fuga l puq) i s dr iven through dou5le V-belts by a va r i ab le -

speid magnetic c lu t ch and a 5 hp motor. The speed i s regula ted by an

e l e c t r o n i c con t ro 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 , an a u x i l i a r y d-c source i s suppl ied f o r t h e

magretic c lutch, which is p r e s e t a t t h e des i r ed speed. This c lu t ch

supply c i r c u i t i s shown schematical ly i n Fig. 7. Relay SR-3 automatical ly

changes over t o t h e a u x i 1 i a . r ~ supply i f any pe r tu rba t ion of t h e normal

con t ro l occurs . The operat ion of t h e pump i s thelz maintained by t h e

aux i l i a ry -c lu t ch supply, while e l e c t r o n i c tubes are changed o r o the r

r e p a i r s are being made t o t h e normal supply. I n t h e event of t h e f a i l u r e

of both c lu t ch suppl ies o r a motor f a i l u r e , s t e p s are taken au tomat ica l ly

t o provide h e a t t o t h e e n t i r e loop, as w i l l be discussed f u r t h e r i n t h e

following sec t ion on alarm and automatic-act ion con t ro l s .

Since t h e pump conta ins t h e only gas- l iqu id 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

f lange . The maximum and minimum l i q u i d l e v e l s are ind ica t ed 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 salt comes i n

contac t with it. A c ross - sec t iona l view of t h e sampling device i s shown i n Fig. 8.

It c o n s i s t s of a dynamic-seal and bal l -plug-valve 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 sal t and a sample with-

drawn 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 ana lys i s ,

i n d i c a t e t h e type and rate of i nc rease of var ious cor ros ion products i n

t h e molten sal t .

I n p repa ra t ion f o r tak ing a sample, a seal i s e s t ab l i shed around t h e

per iphery of t h e sample tube, and t h e i n e r t gas i s introduced t o purge

t h e v o l m e between t h i s seal and t h e b a l l plug valve below. The b a l l

12

PYROMETEQ

SRI-4

OPENS ON CLUTCH

LOW SPEED

OPENS ON

TEMPERATURE

OPENS ON CLUTCH 1

SRI-4

LOW SPEED

OPENS ON

TEMPERATURE

BYPASS OPEN ON OPERATE

CLOSED ON LOW TEMPERATURE

CLOSED ON TEST

(TIME DELAY TRANSFORMER TAP

"OFF"

AMPLIFIER

AUXILIARY CONTROLS

MAIN RESISTANCE HEATER CIRCUIT

5 2 T

OPENS ON LOOP HIGH TEMPERATURE

OPEN ON PREHEAT CLOSED ON OPERATE

I MAIN RESISTANCE HEATERS CONTROL

r-

CLOSES ON

LOW CLOSES TEMPERATURE ON LOOP L'g?' SIMPLYTROL PYROMETER

HETEQ RELAV

TACHOMETER SPEED AND LOW TEMPERATURE CONTROL

IPENS ON LOSS OF CLUTCH

r A-C PUMP MOTOR CIRCUIT POTENTIAL

t 63 ORMAL SUPPLY t MAIN RESISTANCE

HEATER POTENTIAL

TACHOMETER CIRCUIT =@=I L - S U P P L Y FOR BLOWER MOTOR 4

I 0 0-100 Y DC I I

MAIN RESISTANCE pp HEATER Y T E N T I A L -7

CLOSED AT STARTUP OF OPERATION TO

ALLOW PICKUP OF RB. OPEN AFTER STARTUP-

DAMPER CONTROL

c L u r c n AUXILIARY 0 - c SUPPLY

OPEN ON LOSS

OPEN ON RESET AN0 PREHEAT

CLOSEO ON OPERATE

-it--', -OPEN ON RESET SUB STA. AND DIESEL CKT. POT. :LOSE0 ON OPERATE

/;;;;\ AUTOMATIC OPERATION

+ MAIN SUPPLY COOLER RESISTANCE HEATER

Re-6 CLOSEO ON PREHEAT fa OPEN ON OPERATE-

40 KVA TRANSFORMER

0-50" AC

COOLER RECTIFIER f y w I20 Y AC V A R I A C

COOLER PREHEAT CONTROL

SELECTOR SWITCH DEVELOPMENT CLUTCH CONTROL CIRCUIT

INORMAL CLUTCH SUPPLV-I PARTIAL CLUTCH

SUPPLY CONTROL CIRCUIT

Fig. 7. E l e c t r i c a l Schematic of Automatic Action Relays.

r.

1

13

UNCLASSIFIED ORNL-LR-DWG 65062

REMOVABLE HEAD ASS E M B LY --

-\

RMANENT LOOP UNTED ASSEMBLY

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

MINIMUM LIQUID LEVEL - - - - - - - -

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

14

plug valve i s then opened, and t h e d i p tube i s i n s e r t e d i n t o t h e molten

sa l t i n t h e p m p .

sample i s drawn ap i n t o t h e tube.

b a L plug valve closed.

axount of n o l t e n sa l t whtch car, be removed withot1.t deprimicg t h e pump.

A vacuum i s then app l i ed t o t h e d i p tube, and t h e

The d i p tube i s withdrawn, and t h e

Th? nznber of samplzs is l i m i t , & only by t h e

El',, 3 . . L L J fiow of molter- saLt from t'ne pmip i s past t h e d ra i c - t ank

c o x e c t i o n , tlzrough the f i r s t h e a t e r s ec t ion , 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.

yioc:r?ted i n a circular-&Lct a m u i u s through whicn arn'cient a i r i s blown.

To provide t a e rxczss s ry preheat t anpe ra tu re f o r f i l l i n g t h e loop 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 mol t e r salt i c a n emergency

s i t u a t i o i , t h e coo le r c o i l i s provided idith e l e c t r i c a l hea t ing l u g s a t

both ends and i n t h e cen te r f o r e l e c t r i c a l - r e s i s t a n c e hea t ing . The i n l e t

a_rd o d t l e t &re kep t e t t5.e s a ~ e p o t e n t i a l e l e c t r i c a l l y t o confine t h e

flow of ca-rerrt t o tke c o o h r c o i l oLnly. A sepa ra t e 10-kva s a t u r a b l e

core 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 coo le r c o i l f o r use i n

preheat ing c r d x i p g an esnergeacy alarm conditior, .

a t a predeteLrmined rate of approximately 300 axp arid 15 vg and t h e power

i s app l i ed ag tomat i ca l ly m e n r equ i r ed ,

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

Tke c o n t r o l i s set

Other a u x i l i a r y eq".ipment r equ i r ed f o r t h e ope r s t ion of t h e loop

i x h d e a 3000 cfrr. blower, a cool ing o i l suppiy, an3 t h e necessary u t i l -

i t i e s , sdch as cool i2g aZr f o r t h e frozen-plug vaivz, i n e r t gas, and

cool ing watcr. The e z t i r e p~urp, loop, and d r a i n tank assembly i s shown

i n Fig. 3 mourited on z n o b i l e 3011y f o r ease of f a b r i c a t i o n , inspect ion,

and 5 n s t a L a t i o n .

duct a?d t h e a i r d e f l e c t o r i n t h e center , which f o r m a n annular a i r

passage. Tke back h a l f of t h e coo le r duct i s momted on t h e permanent

s t and f r aze , which also con ta ins t h e c i r c u l a t i n g cool ing o i l system,

h e a t e r concections, and t h e pump-drive motor. Mounted over t h e coo le r

duct 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? up r igh t p o s i t i o n by

a solenoid-3eid i a t c h during ope ra t ion of the! loop. I n t h e event 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 erxloses t h e coo le r c o i l t o prevent excessive l o s s

of t ea t .

T2e d s l l y con ta ins one h a l f of t h e i n s u l a t e d coo le r

1 5

4

I

*

Al l c r i t i c a l loop welding i s done by t h e He l i a rc process with i n e r t

cover gas 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 in spec ted v i s u a l l y , by dye penetrant , and by x-ray. Mter

welding, t h e loop i s instrumented with Chromel-Alumel thermocouples and

h e a t e r s .

with shim stock 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 hea t ing 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 lugs, acd t h e freeze-plug valve. Standby h e a t e r s are mounted

on t h e loop p ip ing 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.

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

and d o l l y assembly are tken 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 supp l i e s .

The thermocoiip1.e~ are spot welded t o t h e txbing and covered

After t h e h e a t e r s and thermocouples are at tached,

The loop

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

tubing used, and t h e r e f o r e safeguards must be provided t o prevent s o l i d i -

f i c a t i o n of t h e salt i n t h e loop. The sa l t i n t h e coo le r c o i l w i l l become

s o l i d i n less than 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

app l i ed .

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 operat ing equipment.

An alarm an5 automatic-act ion r e l a y system w a s designed t o pro-

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 ig . 9. Any one of t he alarms shown a t t h e t o p of Fig. 9, i.e., any cond i t ion

which w i l l cause flow stoppage o r adverse temperatures, w i l l au tomat i ca l ly

p l a c e t h e loop i n an isothermal or safe cond i t ion 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 oop being warmed and i n a safe or isothermal cond i t ion while t h e

necessary a c t i o n i s taken t o r e s t o r e t h e equipment t o operat ing cond i t ion .

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 af ter 2 see, and they w i l l

maintain isothermal condi t ions 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 block diagram of Fig. 9 are shown

schematical ly i n Fig. 7. The battery-powered r e l a y R-8 i s de-energized

by r e l a y R-4 t o perform t h e f0b.r Pdnctions which p l a c e t h e loop on

LOSS OF NORMAL AND AUXILIARY LOSS OF PUMP CLUTCH SUPPLIES (PUMP STOPS) MOTOR (PUMP STOPS)

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

LOOP HIGH LOSS OF MAIN POWER LOOP LOW TEMPERATURE TEMPERATURE SUPPLY TO HEATER SECTION

I I 1 I

DROPS LID ON SWITCHES MAIN POWER SUPPLY FROM OPERATE TO COOLER BOX PREHEAT CONNECTIONS ON LOOP

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

-

CONNECTS POWER TO COOLER COIL AT PRESET RATE

I CONNECTS POWER TO EMER- GENCY HEATERS ON LOOP I PIPING AT PRESET RATE

Fig. 9. Block Diagram of Automatic A l a r m Actions.

17

isothermal operat ion. 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 tes ts or t o t h e bus duct supplying power t o t h e loops,

equipmect has been designed and i n s t a l l e d as shown i n block diagram i n

Fig. 10. Should a fa i lu 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 eede r i s made automatical ly wi th in 2 see. The t ime-delay

relzy TD-1 and r e l a y R-3 of Fig. 7 w i l l ho ld i n t h e battery-powered r e l a y

E-6, al lowing t h e traisfer t o be made without d i s t u r b i n g t h e ope ra t ion of

t h e loops .

pe r iod l o c g e r thap 2 see, t h e emergency d i e s e l generator , which s t a r t e d

imnediately, would begin assuming t h e l o a d through a s e q u e n t i a l t imer.

Loads would be 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 loops had power r eapp l i ed w i t h i n 40 see

a f t e r t h e i n t e r r u p t i o n . The 300-kw capac i ty of t h e d i e s e l gene ra to r i s

s u f f i c i e n t t o operate t h e loops i so the rma l ly 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 aga in available.

Should t h e bii i lding e l e c t r i c a l power be unavai lable f o r a

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 loops t h a t g ive

only an aud ib le 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 be

taken by t h e ope ra to r .

cool ing o i l flow, l o s s of’ coo le r p rehea 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 .

These alarms include l o s s of blower motor, low

Operation and Maintenance of a T e s t Loop

The s t a r t u p of a new co r ros ion t e s t i n g loop i s preceded by a series

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 loop i s l e a k t i g h t , t h e

e n t i r e loop i s preheated t o llOO°F with t h e pump s h a f t r o t a t i n g slowly

and t h e cool ing o i l c i r c d a t i n g . The sa l t mixture chosen f o r t h e p a r t i c -

u l a r tes 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 ank i n a molten state a t a

s l i g h t l y h ighe r tempera tme than t h a t of t h e loop. The d r a i n t ank 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 salt t o f i l l t h e loop. I n e r t

gas pressv-re i s admitted t o t h e d r a i n tank and vented from t h e upper

p o r t i o n of t h e loop a t t k e p m p .

18

DIESEL G E N E R AT0 R -- STARTS WHEN POWER FAILS

I 3

SEQUENTIAL TIMER FOR IN- CREMENTAL APPLICATION OF

LOAD

I AUTOMATIC SWITCHING ,

UNCLASSIFIED ORNL-LR-DWG 65069

MANUAL SWITCHING EQUIPMENT

>

I NORMAL BUILDING FEEDER

BUS CUCT

SUPPLYING POWER TO EQUIP- MENT AND CONTROLS FOR 15 LOOPS

ALT E R N AT E BUILDING FEEDER

SUB STATION

SUPPLYING Iio-kva TRANS- FORMER POWER FOR i5 LOOPS

AUXILIARY BUILDING FEEDER

. Fig. 10. Block Diagram of Building Electrical Supply.

,

U

A s t h e sa l t i s slow.ly forced up i n t o t h e loop, i t s path can be

t r a c e d by t h e temperature readings of thermocouples placed along t h e

tub ing .

t h i s l eve l i s maintained by manipulation of gas p re s su re while cool ing

a i r i s suppl ied t o t h e freeze-plug va lve . When t h e temperature of t h e

valve i n d i c a t e s a s o l i d plug, t h e p re s su re i s r e l e a s e d from t h e d r a i n

tank and t h e pump speed :is i nc reased t o begin c i r c u l a t i o n of t h e molten

sal t .

d e s i r e d temperature leve:-. The f i r s t l o a d of sa 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 ean t h e system and i s then dumped i n t o t h e d r a i n

tank and removed.

of salt t o be used f o r t h e co r ros ion t e s t .

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

Power from t h e mafin t ransformer i s a d j u s t e d t o maintain t h e

The f 3 l i n g ope ra t ion i s repeated with t h e supply

When t h e t e s t sa 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 coo le r heat, opening t h e l i d on t h e

coo le 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 - ~ p h e a t e r s e c t i o n

b reake 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,

cool ing a i r flow, and main t ransformer power, as r equ i r ed . When t h e

d e s i r e d cond i t ions are met, a l l t h e c o n t r o l l e r s , alarm se t po in t s , and

automatic func t ion ing r e l a y s are set f o r continuous operat ion.

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 equip-

ment w i l l f u n c t i o n p rope r ly when t h e need arises, a p reven t ive maintenance

program i s c a r r i e d out 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 throw-

over c i r c u i t on the a u x i l i a r y c lutch supply, t he 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 tes ts under t h i s program have been operated with maximum w a l l

temperatures of 1200 t o 1500°F, a temperature d i f f e r e n c e between t h e

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 e r a t u r e s of 1500°F and h ighe r .8

l i m i t e d only by t h e s t r e n g t h of t h e con ta ine 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 obtained i s l imi ted by t h e flow rate and power

a v a i l a b l e . The f o r c e d - c i r c u l a t i o n co r ros ion t e s t f a c i l i t y with eleven

t e s t s t ands showing i n t h e l e f t background i s p i c t u r e d i n Fig. 11. The

remaining f o u r t e s t s t ands are on t h e opposi te s i d e of t h e a is le t o t h e

r i g h t .

0

Previously tes ts were conducted with w a l l t e m -

The w a l l temperatures obtained are

20

I

b

21

Summary

Twenty-five loops hsve been f a b r i c a t e d with both INOR-8 and Incone19

and have operated under t h i s program f o r an 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-8 and seven of Inconel, operated from one t o two and a ha l f years

before being terminated 2nd examined meta l lographica l ly .

The long-term operat ion and metallographic examination of t hese

loops w a s inst rumental i n t h e acceptance of INOR-8 as t h e conta iner

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

i s expected t o be less than 1 mils /yr a t t h e design opera t ing temperature

of 1225'F.

The expected corrosion

Corrosion specimen weight loss and salt sample d a t a from t h e s e loops

ind ica t ed t h a t t h e primary cor ros ion product i s chromium and t h a t an

e s s e n t i a l l y cons tan t value w a s achieved af ter approximately 5000 h r of

o p e r a t i o n . l l

Acknowledgments

Many persons have made important con t r ibu t ions t o t h e design and

opera t ion of t hese f a c i l i t i e s .

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 opera t ion of t hese loops w a s due t o a l a r g e ex ten t t o

W . H. Duckworth and t h e s h i f t operat ions group under R. Helton, and t o

many o the r s t o o numerous t o mention.

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

22

R e f e r e ne e s

1. J. H . &Van and

2 .

3 "

4.

5.

6.

7.

8.

9.

10 *

11.

J . D. Man S a l t Mixtures, Trans. Am.

y, Corrosion P rope r t i e s of Fused-Fluoride Nuclear Soc., 1 (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).

5. ?. Biake ly , Molten S e l t Coxpositions, Oak 3idge National Laboratory Report C F - 5 8 - 6 - m J u n e 12 , 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 . L and 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 l100-150G°F, 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 Rat ional Laboratory Report \8 ORNL-2 (March 7,1960)

'i'. 3 . Housley apd 2. Pa t r i a rca , Procedure Spec i f i ca t ioL - PS-2 f o r D.C. AFX Weifiins of - l n c o n e l Tubing f o r Higk! I Corrosion 4-pplications, Oak Ridge Eat ions1 Lcboratory.

W . D. Manly -_ e t hl., - ?i le ta l lsrgical P rob lem i n Molten Fluoride Systems, Proceedirgs of t h e SGcond United Nations I n t e r n s t i o n a l Conference on t h e Peaceful Uses of Atomic Energy, Vol. 7, pp. 223-34, United r\Tatlozls, Geneva, 1958.

J. A. Lane, ?. G . bkcPhersori and F. Maslar?, F lu id Fuel Reactors, p . 596, Addisoi-We.cle;r, Reading, Mass., 19587

S. E. Beail e t -- &lo, Moit?n-Sal t Reactor Experiment Prel iminary Hazards Report, Ozk 3idge NLtioral Laboratory Report CF-62-2-46 (Feb. 28, 2.961).

J. E. &'an and R . E . Evans III, Corrosion Bzhavior of Reactor Materials ir F ~ u o ~ c ! . ~ S a l t Mi x tu res Oak Ridge National Laboratory Repo-ct TX-329 (Septenber 19, ---, 19 2

I \ ' d i

c

23

DISTRIBUTION I

1. MSRP D i r e c t o r ' s Office 43. W . B. McDonald 2. G . M. Adamson 3. L. G . Alexander 4. S. E. Bea l l 5. M . Bender 6. E. S. B e t t i s 7. F. F. Blankenship 8. E. G . Bohlmain 9. D. L. Clark

10. J . A. Conlin 11. W . H. Cook

lZ.-l5. J. L . Crowley 16. J. H . DeVan 17. R . G . Donnelly 18. J. R. Engel 19. C . H . Gabbard 20. R . B. Gal laher 21. W . R. Grimes 2 2 . A. G . Gr inde l l 23. R . H . Guymon 24. P. H . Harley 25. P. N. Haubenreich 26. R . Helton 27. E. C . Hise 28. H. W . Hoffman 29. P. P . Holz 30. T. L . Hudson 31. R . J. K e d l 32. J. J. Keyes, Jr. 33. S. S. Kirslis 34. A. I . Krakoviak 35. J. W . Krewson 36. J. A. Lane 37. E. M. Lees 38. R . B. Lindauer 39. M . I . Lundin 40. R . N. Lyon 41. H. G . MacPherson 42. E. R . Mann

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H. F. McDuffie C . K. McGlothlan R . L . Moore J. C . Moyers W . R . Osborn P. P a t r i a r c a H. R . Payne M. Richardson R. C . Robertson H. W . Savage A. W . Savolainen D. S c o t t J . H. Sha f fe r M. J. Skinner G. M. Slaughter A. N. Smith P. G . Smith I. Spiewak J. A. Swartout A. Taboada J. R . Tallackson R . E. Thoma D. B. Trauger W . C . U l r i c h C . F. Weaver B. H. Webster A. M. Weinberg J. C. White L . V. Wilson Cen. Res. Lib. (CRL) Doc. Ref. See. (DRS) Lab. Records (LRD) Lab. Records - RC Div. of Tech. I n f o . Exten. Res. and Dev. Div. (ORO) Reactor Div. (ORO) ORNL Pa ten t Off ice

External

110.-111. D. F. Cope, Reactor Div., AEC, OR0 112. A. W . Larson, Reactor Div., AEC, OR0 113. H. M. Roth, Div. of R e s . and Dev., AEC, OR0 114. W . L. Smalley, Reactor Div., AEC, OR0 115. J. Wett, AEC, Washington