ORNL-TM-3141 by Jon Morrow

This repurt was prepared as an account of work sponsored by the United States Governnwnt. Neither the United States nor the l h t e d States Atornir Energy Commission, nor any of their employee\, nor any of their contractors, subcontractors, or their employees, nialtes any warranty, express or itnplied, or a s ~ ~ l ~ iany e s legal liability or responsibility for t h e accuracy, completeness or usefulness of any informatioi, apparatus, product or process clisclospd. or represents that i t s use would not infringe privately owned rights.

ORNL-TM-3141 Contract

I ~ O . W-7405-eng-26

CHEMICAL TECHNOLOGY D I V I S I O N

ENGIPSEERING DEVELOPMENT STUDIES FOR MOLTEN-SALT BREEDER REACTOR PROCESSING NO. 6

L. E. McNeese

DECEMBER 1971

OAK RIDGE NATIONAL LABORATORY

Oak Ridge, Tennessee o p e r a t e d by

37830

UNION CARBIDE CORPORATION for the U . S . ATOMIC ENERGY COMMISSION

Reports p r e v i o u s l y i s s u e d in t h i s s e r i e s ftre as f o l l o w s : P e r i o d ending Merch 1968 P e r i o d end-ing June 5.968

P e r i o d ending September 1968

Period errding Deceniber 1968

1969 P e r i o d ending June 1969 P e r i o d ending Septeirihey 1969 P e r i o d ending March

Period ending December 3969

iii

CONTENTS Page

............................. 1. IBTRODUC'TIOB . . . . . . . . . . . . . . . . . . . . . . . . . SUMMARIES

MSBR FU%L PROCESSING USING FLUORINATION.. AND THE IMETAL TRANSFER PROCESS

AXIAL

3.1

Previous S t u d i e s on Axial D i s p e r s i o n

2.2

2.3

3 2

Equipment and Expel-imental Technique

..........

3.3

E f f e c t s o f Gas I n l e t Diameter and Column Diameter on Axial Dispersion

3.4

Gas Holdup

3.5

....................... i n Bubble Columns . . . . . . . . . . . . . .

D i s c u s s i o n of R e s u l t s and F u t u r e Experiments

CONSIDERATIONS OF c(iwrmuous FLUORINATORS ITY TO MSBR PROCESSING

4.1 4.2

4.3

4.4 4.5

REDUCTIVE EXTRRCTlON

................ Equilibrium Data and C o n c e n t r a t i o n s . . . . . . . . . . . Flowsheet Ana1:ysi.s ................... E f f e c t of Contamination of L i C l w i t h F l u o r i d e . . . . . . DISPERSION IS OPEH BUBBLE COIiUMNS . . . . . . . . . . . .

m~ THEIR

......

1-3 13

16 16 17

19 22

APPLICABIL-

.................... Types of F l u o r i n a t o r s . . . . . . . . . . . . . . . . . . Experience Related t o F l u o r i n a t i o n of Molten S a l t f o r U r a n i u m Removal . . . . . . . . . . . . . . . . . . . . . Mathematical A n a l y s i s of Open-Column Continuous Fluorinators . . . . . . . . . . . . . . . . . . . . . . . . . . E v a l u a t i o n o f F l u o r i n a t i o n Reaction Rate Constant . . . . P r e d i c t e d Performance of Open-Column Continuous Fluorinators . . . . . . . . . . . . . . . . . . . . . . . . . .

24 26

311

5 . USE OF RA.DIO-FREQUElJCY IWDUCTION HEATING FOR FROZEN-WALL FLUORINATOR DEVELOPMENT STUDIES . . . . . . . . . . . . . . . . . . . 39

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

5.1

Mathematical A n a l y s i s

5.2

C a l c u l a t e d R e s u l t s f o r a Molten-Salt F l u o r i n a t o r

5.3

Experimentally Measured

6 . MSRE DISTILLllTION EXPERIMENT

.... H e a t G e n e r a t i o n Hates . . . . . . .................

41 46 46

3 4456 0383042 4

iv CONTENTS ( c o n t i n u e d 1

'I .1

gquipanent and Experimental P r o c e d u r e

T.2

Ikvelopment and T e s t i n g o f a Pump f o r

.......... Circulating L i C l .

.... 9 . STUDY OF .TILE P U X I F I C A T I O N OF SALT BY- CONTINIJOUS METHODS . . . . 9.1 I'revious Work (1n. S a l t .Purification . . . . . . . . . . . 9.2 Experimental Fquipn~ent . . . . . . . . . . . . . . . . . 9.3 Gas Sirpply and F u r i f i c a t i o n S y s t m s . . . . . . . . . . . 8 . ELECTROLYTIC CELL DEVELOPMXNT:

9.4 9.5

STATIC CELL EXPFBIikEIYTS

lnstnllation of Equipment and I n i t i a l checkout

Anticipated lCxperiments and Operating P r o c e d u e a

57 53

..... ....

S~ICONI'I~TJOUS REDUCTIVE EXTRACTlON FXPERIMF3'I'S 7 s A MILD.-STEEIi FAC1:LTTY

10.1

........................... Equipment M a d i f i c n t i o n s . . . . . . . . . . . . . . . . .

10.2 Treat.me n-t of B i s m u t h and S a l t ; Adjustment of Zirconium Jji s t r i b u t i o n X a t i i ~

................... 1 0 . 3 Iiydrodynmic Experiments HR-9. -10. -11. and -12 . . . l0.h Maintenance of Equipment . . . . . . . . . . . . . . . . 11. IIEFERElYCES . . . . . . . . . . . . . . . . . . . . . . . . . . a

75 75 79 80

SUMMARIES

MSBR FUEL PROCESSING USING FLUORINATION--REDUCTIVE EXTRACTION AND THE METAL TRANSFER PROCESS

A combined f l o w s h e e t f o r p r o c e s s i n g MSBR f u e l s a l t by f l u o r i n a t i o n - -

r e d u c t i v e e x t r a c t i o n and t h e metal t r a n s f e r p r o c e s s h a s been devised.

C a l c u l a t i o n s have been made, based on r e c e n t l y measured distributior, co-

e f f ' i c i e n t s , r ' o r a number of r a r e - e a r t h and a c t i n i d e elements.

Reference

c o n d i t i o n s f o r t h e i s o l a t i o n of p r o t a c t i n i u m on a 10-day c y c l e are g i v e n , and t h e e f f e c t s of s e v e r a l p a r a m e t e r s a s s o c i a t e d w i t h r a r e - e a r t h removal are discussed.

Conditions t h h t r e s u l t i n r a r e - e a r t h removal t i m e s of

about 1 5 t o $0 days are d e s c r i b e d .

The e f f e c t of contamination of t h e

L i C l w i t h f l u o r i d e i o n s was examined.

Tt w a s found t h a t t h e f l u o r i d e

c o n c e n t r a t i o n will have t o b e m a i n t a i n e d below about 2 n o l e

% i n order

t o a v o i d a h i g h thorium & i s c a r d r a t e .

AXIAL DISPERSION I N OPEN BUBBLE COLUMNS Measurements of a x i a l disper*sion d u r i n g t h e c o u n t e r c u r r e n t flow of

a i r and water were made i n 1.5-,

of g a s i n l e t d i a m e t e r s ,

2-, and 3-ia.-diam

columns w i t h a r a n g e

I n t h e "slugging9' r e g i o n , t h e d i s p e r s i o n c o e f f f -

c i e n t w a s found t o be independent of gas i n l e t ; disuneter and dependent o n l y on t h e v o l u m e t r i c g a s flow r a t e f o r a l l colwnn d i a m e t e r s .

In the

"bubbly" r e g i o n , the d i s p e r s i o n c o e f f i c i e n t a l s o a p p e a r s t o depend o n l y on t h e v o l u r e t r i c gas flow r a t e when t h e column d i a m e t e r i s 2 i n . o r larger.

Gas holdup i n bubble columns w a s a l s o determined f o r a r a n g e

of o p e r a t i n g c o n d i t i o n s . CONSIDERATIONS OF CONTINUOUS FLUORINATORS AND THEIR APPLICABILITY TO MSBR PROCESSING A g r e a t d e a l of e x p e r i e n c e has been accumulated in removing uranium

from molten s a l t by .... b a t c h f l u o r i n a t i o n ; however, i n f o r m a t i o n on continuous fluorinators is sparse, particularly

on f l u o r i n a t o r s c a p a b l e of h a n d l i n g

s a l t f l o w r a t e s up to about 100 f t /day.

Experience w i t h f l . u o r i n a t o r s

i s reviewed, and p o s s i b l e types of F l u o r i n a t o r s a r e d i s c u s s e d .

A math-

emat ic a1 anal y s is o f ope n-c 01 m n c o n t inuoks flimr in a t o r s is pr e s e n t ed

and p r e d i c t i o n s arf made concerning t h e performance of open-coli-mn continuous f l u o r i n a t o r s f o r MSBR p r o c e s s i n g a p p l i c a t i o n s . USE OF I W LO-FXEQUhNCY INDUCTTON PEATTNG FOR FROZZN-WALL FLUORiNATOR DhVELOPMENT STIJDIES

13adio-frequency i n d u c t i o n h e a t i n g i s b e i n g c a n s i d e r e d 8,s a method f o r g e m r a t i n g h e a t i n molten salt i n s t u d i e s of f r o z e n - w a l l f l u o r i n a t o r s with nonradioactive salt.

Two c o n f i g u r a t i o n s f o r an i n d u c k i v e l y h e s t e d

@ont;iniiousf l u o r i n a t o r are d i s c u s s e d .

Calcul.a%ions fez" t h e f i r s t con-

f i g i i r a t i o n show t h a t s u f f i c i e n t h e a t would be generated i n a J-.g-in.-dim

molten zone by a c o i l c u r r e n t of 24.7 A a t 500 kHz t~ m a i n t a i n a 1.5-i.n.t h i c k frozen salt film with

100°C t e m p e r a t u r e d i f f e r e n c e a c r o s s t h e

‘The c a l c u l a t e d e f f i c i e n c y of h e a t i n g t h e s a l t itas abou-t 34%; t h e

fj.lr;.

h e a t g e n e r a t e d i n .the metal. w a l l s w a s about 1.05 t i m e s t h e h e a t g e n e r a t e d in the salt.

I n experiments w i t h a 3-in.--dia.m c!:zrgr

round:.d by a 6 - i n . - ~ _ o n g s e c t i o n o f

6-in. sched

‘>f30% H,SC?s

sur-

IcO p i p ? , t h e measured

r a t i o o f h e a t g e n e r a t e d i n t h e p i p e t o t h a t i n the a c i d w a s 1 - * 3 ?whereas t h e calculai;ed r a t i o f o r t h e system w a s

0.58.

T h i s d i s c r e p a n c y shows

t h a t t h e d e s i g n of an experimental f l u o r i n a . t Q r u s i n g inducti.oxi h e a t i n g

w i l l d e p n d h e a v i l y on e m p i r i c a l d e s i g n r e l a t i o n s

The second c o n f i g u r a t i o n c o u l d n o t be exam?:ned m a t h e m a t i c a l l y .

Ex-

p e r i m e n t a l measurements using t h i s c o n f i g u r a t i o n with 30% H3SOl+ showed t h a t t h e ratio of h e a t g e n e r a t e d i n t h e p i p e t o t h a t geilerated i n the a c i d was

0.069,

The c o u p l i n g of t h e magnetic f i e l d w i t h t h e a c i d w a s weaker w i t h

this configuration than with t h e f i r s t configuration.

MSRE DiST1CCATION EXPERIMXNT

Data o b t a i n e d i n the MSRE D i s t i l l a t i o n Experinr,ent f o r t h e e f r e c t i v e

r e l a t i v e v o l s t i l i t j es, w i t h respect, t o L i F , of B e F

, ZrF4,

and f l u o r i d e s

vii

of 95Zr, 144Ce, 147Pm, 155Eu,,Y'9

9oSr, "Sr,

and 137Cs were examined

i n a n a t t e m p t t o e x p l a i n t h e anomalous r e l a t i v e v o l a t i l i t i e s o f a l l

These d a t a were s c r u t i n i z e d c l o s e l y f o r

f i s s i o n p r o d u c t s except 9 5 Z r

p o s s i b l e e v i d e n c e s of e i i t r a i r m e n t , c o n c e n t r a t i o n p o l a r i z a t i o n , and sample c o n t a m i n a t i o n .

Although a l l t h r e e e f f e c t s were p r o b a b l y p r e s e n t ,

we believe that

c o n t a m i n a t i o n w a s t h e major r e a s o n f o r t h e d i s -

sizrnlple

c r e p a n c i e s between t h e tralues o b t a i n e d i n t h i s experiment and t h o s e

measured under e q u i l i b r i u m c o n d i t i o n s

The Low r e l a t i v e v o l a t i l i t y

observed f a r L 3 7 C s i s n o t e x p l a i n e d by any of t h e t h r e e mechanisms examined.

DEVELOPMENT OF THE METAL TRPJSFER PROCESS Equipment h a s been f a b r i c a t e d f o r s t u d y i n g and demonstrating t h e

metal t r a n s f e r p r o c e s s f o r removal of rare e a r t h s from MSl3R f u e l s a l t .

Work t h a t w i l l demonstrate a l l phases o f t h e p r o c e s s i s under way. Lanthanum a.nd 14''1id w i l l b e e x t r a c t e d from f u e l c a r r i e r s a l t by c o n t a c t w i t h bismuth c o n t a i n i n g thorium. t i v e l y transferred t o LiC1.

The rare e a r t h s w i l l t h e n b e s e l e c -

The f i n a l s t e p of t h e experiment w i l l con-

s i s t of removing t h e rare e a r t h s from t h e LiC1 by c o n t a c t w i t h bismuth

c o n t a i n i n g 0 . 4 m ~ l ef r a c t i o n l i t h i u m .

S e v e r a l pumps made of q u a r t z have been designed and kested w i t h molten L i C 1 a t 6 5 0 O C i n a n e f f o r t t o develop a d e v i c e t h a t i s c a p a b l e

of c i r c u l a t i n g t h e L i C l i n t h e experiment.

Although d i f f i c u l t y h a s

been encountered w i t h d e v i t r i f i c a t i o n of t h e q u a r t z , we b e l i e v e t h a t t h e L i C l can be s u f f i c i e n t l y p u r i f i e d t o p e r m i t a q u a r t z pimp t o perform satisfactorily*

One pump w a s found t o be o p e r a b l e a f t e r t e s t a w i t h LiCl

a t 650째c over a lt;-day p e r i o d ,

ELECTROLYTIC CELL DEVELOPMXNT :

STRTIC CELL EXPERIPIENTS

A s t a t i c c e l l e l e c t r o l y s i s experiment was made i n an a l l - m e t a l cell

t o determine whether t h e p r e s e n c e o f q u a r t z c o n t r i b u t e d t o t h e f o r m a t i o n

viii of t h e b l a c k material found t o b e p r e s e n t i n t h e salt .=base i n o t h e r e l e c t r o l y s i s experiments.

No such m a t e r i a l w a s o’oserved i n t h i s experi-

ment; however, t h e lack of a b i s i m t k cathode may have resulted i n a sys-

tem t o o d i f f e r e n t from t h e p r e v i o u s c e l l s t o a l l o w us

i J ~ 7 Arav

f i r m con-

clusions. STTJ9Y O? 7 3 PUHIFICATION OF’ SALT BY

CONTINUOUS NETHODS

To d a t e , t h e molten s a l t reqiii.:red f o r developnient work 2.s

; ~ l las

for the MSRE has been p u r i f i e d from harnzful contaminants (sui.fc:t., cxygen,

and i r o n f l u o r i d e ) by a batch p r o c e s s .

It i s b e l i e v e d t h a t -the c o s t s o f

t h e l a b o r a s s o c i a t e d w i t h s a l t p u r i f i c a t i o n can be reduced c o n s i d e r a b l y by u s i n g a continiious p r o c e s s f o r t h e most time-consuming

t h e hydrogen r e d u c t i o n of i r o n f l u o r i d e ) .

o p e r a t i o r (i.e.,

We have i n s t a l l e d equipment i.n which molten s a l t aiid hyfk-ss?c -::;7

be c o u n t e r c u r r e n t l y c o n t a c t e d i n a I.. 25-in.-dism,

co;mn.

81-in.-1.0cg

2d;~ec-

T’he system i s f a b r i c a t e d o f n i c k e l , and p r o v i s i o n i s made f o r

f e e d i n g about 1 5 1 i t e s . s of mol.l;en salt through t h e calimn a t f l o w r s t e s

of 70 to 250 crn 3 /min.

The equipment and gas supply systems a r e d e c c : - i k r ~ d z

and t h e a n t i c i p a t e d experirnental program i..s o u t l i n e d . SEMTCOWINUOUS REDIJCTPVE EXTRAC’I’ION EXTERIMENTS I N A MITiJI-STEEL FACILITY A new column, packed w i t h 1/4--in. molyb~.enm Raschig rings, was

i i i s t a l l e d i n t h e system.

Minor changes were mac?e i n some o f t h e p i p i n g .

Three s i i c c e s s f b l hydrodynamic experiments w e x made i n which bismuth and moJ.ten s a l t were c o n t a c t e d c o u n t e r c u r r e n t l y .

The r e s u l t s a r e i n

e x c e l l e n t agreement w i t h a f l o o d i n g c o r r e l a t i J n developed from work with the mercury-water system.

R e s u l t s o f a hplrodynamic experiment

w i t h s a l t flow o n l y e s t a b l i s h e d t h a t t h e p r e s s u r e drop f o r t h e new coliunn was i n s a t i s f a c t o r y agreement w i t h -@’tiat p e d i c - t e d from a l i t e r -

a t u c correlation.

1. INTRODUCTION A m o l t e n - s a l t b r e e d e r r e a c t o r (MSBH) w i l l b e f u e l e d w i t h a molten f l u o r i d e m i x t u r e t h a t will c i r c u l a t e t h r o u g h t h e b l a n k e t and c a r e r e g i o n s

of t h e r e a c t o r and t h r o u g h t h e primary h e a t exchangers.

W e are develop-

i n g p r o c e s s i n g methods for use i n a cl-ose-coupled f a c i l i t y f o r removing

f i s s i o n p r o d u c t s , c o r r o s i o n p r o d u c t s , and f i s s i l e materials from t h e molten f l u w i d e m l x t u r e ,

Several o p e r a t i o n s a s s o c i a t e d w i t h MS8R p r o c e s s i n g a r e under s t u d y . The remaining p a r t s ol" t h i s r e p o r t d i s c u s s :

(1)a f l o w s h e e t f o r process-

i n g MSBR f u e l s a l t by f l u o r i n a t i o n - - r e d u c t i v e

e x t r a c t i o n and t h e n e t a l

t r a n s f e r p r o c e s s , ( 2 ) measurements o f a x i a l d i s p e r s i o n c o e f f i c i e n t s i n open bubble columns, ( 3 ) c o n s i d e r a t i o n s of continuous f l u o r i n u t o r s and t h e i r a p p l i c a b i l i t y t o MSBIi p r o c e s s i n g ,

(4) a n

e v a l u a t i o n of r a d i o -

frequency i n d u c t i o n h e a t i n g f o r frozen-wall f l u o r i n a t o r development s t u d i e s , ( 5 1 a n examination o f s e v e r a l e x p l a n a t i o n s f o r t h e anomalous r e l a t i v e v o l a t i l i t y d a t a o b t a i n e d i n t h e MSRE D i s t i l l a t i o n Experiment,

(6)t h e d e s i g n and t e s t i n g

o f equipment for demonstration of t h e m e t a l

t r a n s f e r process for removal of r a r e e a r t h s from MSBR f u e l c a r r i e r sait,

( 7 ) t h e o p e r a t i o n of a s t a t i c e l e c t r c l y t i e c e l l i n an all-meta~. system, ( 8 ) a s t u d y of t h e p u r i f i c a t i o n of salt by c o n t i n u o u s methods, and ( 9 ) experiments conducted i n a m i l d - s t e e l r e d u c t i v e e x t r a c t i o n f a c i l i t y

t o i n c r e a s e o m u n d e r s t a n d i n g of t h e hydrodynamics of packed column o p e r a t i o n d u r i n g t h e c o u n t e r c u r r e n t flow of molten s a l t and bismuth

T h i s work was c a r r i e d o u t i n t h e Chemical Technology D i v i s i o n d u r i n g

t h e p e r i o d J a n u a r y t h r o u g h March 15TOo 2

MSBR FUEL PROCESSING U S I N G FLUORINATION--HEDUCTrVE AND THE METAL TRANSFER PROCESS

M. J. Bell R e c e n t l y , we reported'

EXTMCTIGN

L. E. McNeese

t h e development of t h e metal t r a n s f e r p r o c e s s

f o r e x t r a c t i o n of r a r e - e a r t h f i s s i o n p r o d u c t s Erom MSBH fuel s a l t and

2 p r e s e n t e d removal times f o r s e v e r a l rare e a r t h s f o r a range of o p e r a t i n g conditions.

Noting .t;hat t h i s p r o c e s s e l i m i n a t e d t h e need for l a r g e e l e c -

t r o l y t i c c e l l s , w e i n t r o d u c e d another p r o c e s s n o t r e q u i r i n g an e l e c t r o l y t i c c e l l , namely, t h e f l u o r i n a t i o n - - . r e d . u c t i v e e x t r a c t i o n p r o c e s s f o r i s o l a t i o n of p r o t a c t i n i u m from f u e l s a l t .

S i n c e t h e n , we have d e v i s e d a combined

MSBR p r o c e s s i n g f l o w s h e e t t h a t uses f l u o v i n a t i o n - - r e d u c t i v e e x L r a c t i o n f o r the i s o l a t i - o n o f protac-Liniurn and the metal tyansfer process f o r raree a r t h removal.

A range of o p e r a t i n g c o n d i t i o n s for t h e p r o c e s s i n g p l a n t

has been examined, and t h e MATADOR code

has been used t o c a l c u l a t e t h e

b r e e d i n g ra.tio corresponding to each s e t o f c o n d i t i o n s .

Additional in-

f o r m a t i o n on t h e d i s t r i b u t i o n of r a r e ea,rths between L i C l and B i con-tain-

i n g r e d u c t a n t h a s become a v a i l a b l e ; t h i s i n f a r m a t i o n i n d i c a t e s that sati s f a c t o r y removal t i m e s can b e o b t a i n e d f o r Ea, Nd, and Sm, as w e l l as f o r Eu and L a ( a s p r e v i o u s l y r e p o r t e d ) . 2.1

E q u i l i b r i u m Uata and C o n c e n t r a t i o n s

F e r r i s and co-workers3 have measured t h e d i s t r i b u t i o n c o e f f i c i e n t s

of s e v e r a l f i s s i o n p r o d u c t s and a c - t i n i d e elements between a number of a c c e p t o r s a l t s and molten bismuth c o n t a i n i n g lithi.um.

A t a given

t e m p e r a t u r e , t h e d i s t r i b u t i o n c o e f f i c i e n t s f o r an element M c a n b e e x p r e s s e d as log D

where XLi

= n log X

I,i

log

i s t h e mole f r a c t i o n o f I-ithium i n t h e bismuth p h a s e , n i s

t h e v a l e n c e of M i n t h e s a l t p h a s e , and l o g F&

i s a constant.

The

d i s t r i b u t i o n c o e f f i c i e n t i s d e f i n e d as

P' I

mole f r a c t i o n of M i n bismuth phase rno1.e f r a c t i o n o f M i n s a l t phase

T h e i r r e s u l t s , swnmarized. i n Table I., i n d i c a t e t h a t e i t h e r L i C l ar L i B r

would c o n s t i t u t e a s u i t a b l - e a c c e p t o r s a l t , and t h a t s a t i s f a c t o r y removal

Values o f l o g K" Derived from D i s t r i b u t i o n Coefficient Data

Table I..

l o g D = n log XLi + l o g K

Temperature ("C)

Salt

630 640

1Xl LiCl

640 640

LEI-LiF (98.1-1.9 mole %) LiC'1-LiF (96-4 mole %)

640

LiCl-LiF (90-10 mole %)

600

LiC1-LiF (80-20 mole %)

640

LiCI-LF (80-20 mole %)

700

LKI-LiF (80-20 mole '%)

575 600

LiHr LiBr

640

LiHr

650 700

LiBr LiBr

600

LiBr-LiF (90-10 mole 76)

600

LiBr-LiF (80-20 mole %)

Element

log K* 2.301 1.702 7.973 8.633 2.886 15.358 17.838 11.278 13.974 12.90 14.7 10.80 7.288 11.309 7.235 7.644 10.964 7.124 10.629 6.132 9.602 1.497 1.443 9.07Y 8.919 16.16

8.266 8.834 1.358 1.316 8.430 8.158 12.380 7.840 11.373

4 t i m e s can h e o b t a i n e d f o r - B a , La, Nd, Sm, and Eu.

These d a t a were used

t o e v a l u a t e t h e performance of t h e metal t r a n s f e r proecss f o r removing

s t r o n t i u m , barium, and t h e r a r e e a r t h s from MSBR f u e l s a l t .

w a s assumed t o d i s t r i b u t e i n

Strantiim

manner sjmi1a-r t o barium, and t h e

t r i v a l e n t rare e a r t h s f o r which d i s t r i b u t i o n d a t a were not a v a i l a b l e

were assumed t o have d i s t r i b u t i o n c h a r a c t e r i s t i c s l i k e t h o s e oif neodymi.iim

. 'I'hese assumptions

aTc3

b e l i e v e d t o be c o n s e r v a t i v e .

Flowsheet A4nalysis

2.2

A co1ifoi:ied fl-owsheet f o r p r o c e s s i n g MSBR f u e l s a l t u s i n g f l u o - 'i n a 1.

tion--reductive

e x t r a c t i o n and t h e metal t r a n s f e r p r o c e s s i s shown i n

F i g . 1. The effec.Ls of vai-ious o p z r a t i n g parameters for t h e Pa i s o l a -

tion system on t h e Pa remova.1- t i m e and t h e uranium i n v e n t o r y i n the Pa decay t a n k have been r e p o r t e d p r e v i o u s l y . '

A 10-day p r o t a c t i n i u i i

removal time i s o b t a i n e d w i . t h a f u e l s a l t flow rate o f 0.88 gpm (1.0-

day p r o c e s s i n g c y c l e ) , a bismuth f l o w r a t e o f 0,23 gpm, two s t a g e s

i n the lower c o n - t a c t o r , s i x t o e i g h t stages i n t h e upper c o n t a c t o ~ ~ and col.ufln d i a m e t e r s of l e s s t h a n 8 i n .

t o 300 f t 3 i s r e q u i r e d .

A decay t a n k volume of 200

Reductant must he s u p p l i e d a t the r a t e of

340 to 420 e q u i v a l e n t s p e r day, which c o s t s 0.0.12 t o 0 . 0 1 5 mill/kWhr.

T h i s system also r e s u l t s i n a 10-day removal time f o r m a t e r i a l s that

are mare noble t h a n thorium and do iiot form v o l a t i l e f l u o r i d e s d u r i n g

f l u o r i n a t i o n ; t h e s e i n c l u d e Z r , 23iPa, o t h e r comosion products.

I?d,

Rh, Pd, Ag, Cd, I n , N i , and

The c o n c e p t u a l f l o w s h e e t ( F i g . 2 ) f o r t h e metal t r a n s f e r p r o c e s s i n c l u d e s f o u r s a l t - m e t a l c o n t a c t o r s t h a t o p e r a t e a t 64OOC.

F u e l sal-t;

from t h e Pa isola-Lion system, which i s f r e e of U and Pa b u t which con-.

tains t h e rare earths a t the r e a c t o r c o n c e n t r a t i o n , i s c o u n t e r c u r r e n t l y

c o n t a c t e d w i t h B i c o n t a i n i n g approximately 0.002 mole f r a c t i o n L i and

0.0025 mole f r a c t i o n Th (90% of t h e s o l u b i l i t y o f thorium a t 640째C) i n

c o n t a c t o r 1.

S i g n i f i c a n t f r a c t i o n s of t h e r a r e e a r t h s t r a n s f e r t o t h e

downflowing m e t a l s t r e a m and are c a r r i e d i n t o eontactox. 2 .

Here,. t h e

ORNL DWG 70-2811

Fig. 1. Flowsheet f o r Processing a S i n g l e - F l u i d XSER by FluorinaE x t r a c t i o n and the Metal T r a n s f e r Process.

tion-Zeductive

SALT T o - - - - - - ' REA@'$0 R

EXTRACTOR 1 I

( N o u or Pal

OLE FRAC. I..i 1

Fig. 2. Metal T r a n s f e r Process for Xemoval of Rare Earths f r o m a Si ngl.e-Fluid MSBR.

7 bismuth stream i s m n t a c t e d c o u n t e r c u r r e n t l y w i t h LiC1, and s i g n i f i c a n t

f r a c t i o n s of t h e r a r e e a r t h s and a t r a c e of t h e thorium t r a n s f e r t o t h e

LiC1.

The r e s u l t i n g E i C l stream i s t h e n r o u t e d t o c o n t a c t o r

4, where

i t i s c o n t a c t e d w i t h a bjsmuth s o l u t i o n c o n t a i n i n g 0.05 mole f r a c t i o n

l i t h i u m f o r removal of t h e t r i v a l e n t r a r e e a r t h s .

About 2% o f t h e L i C l

i s r o u t e d t o c o n t a c t o r 3, where it i s c o n t a c t e d w i t h a bismuth s o l u t i o n c o n t a i n i n g 0 . 5 mole f r a c t i o n l i t h i u m for removal of t h e d i v a l e n t r a r e e a r t h s (Sro and ELI) and the a l k a l i n e e a r t h s ,

3 and

The LiCl from c o n t a c t o r s

( s t i l l c o n t a i n i n g same r a r e e a r t h s ) i s t h e n r e t u r n e d t o con-

tactor 2, The t r i v a l e n t and d i v a l e n t r a r e e a r t h s a r e removed from t h e TJiC.I.

i n s e p a r a t e c o n t a c t o r s i n o r d e r t o minimize t h e mount of l i t h i u m r e -

quired.

Removal of t h e s e elements i n s e p a r a t e c o n t a c t o r s a p p e a r s ad-

visable f o r several reasons.

A h i g h l i t h i u m c o n c e n t r a t i o n i n t h e bis-

muth i s r e q u i r e d f o r o b t a i n i n g a d e q u a t e l y h i g h d i s t r i b u t i o n c o e f f i c i e n t s for t h e d i v a l e n t r a r e e a r t h s . However, t h e s o l u b i l i t i e s of t h e t r i v a l e n t r a r e e a r t h s i n bismuth are much lower t h a n t h o s e o f t h e d i v a l e n t elements,

A l s o , t h e p r o d u c t i o n r a t e for t h e t r i v a l e n t r a r e e a r t h s i s

s e v e r a l t i m e s t h a t o f t h e d i v a l e n t elements. C a l c u l a t i o n s were made t o i d e n t i f y t h e i m p o r t a n t system parameters

f o r t h e metal t r a n s f e r p r o c e s s .

F i g u r e 3 i l l u s t r a t e s t h e e f f e c t of t h e

bismuth flow r a t e through c o n t a c t o r s 1 and 2 on t h e removal t i m e for neodymium, a t y p i c a l . t r i v a l e n t r a r e e a r t h ,

and samarium, a t y p i c a l

d i v a l e n t r a r e e a r t h , f o r a f i x e d L i C l flow r a t e .

The d i v a l e n t material-s

d i s t r i b u t e l e s s r e a d i l y t o t h e metal Phase, and h i g h bismuth f l o w rates

axe r e q i l i r e d t o a c h i e v e s i g n i f i c a n t removal of t h e s e materials. o t h e r hand, F i g .

On t h e

i l l u s t r a t e s t h a t , for a f i x e d bismuth flow r a t e , t h e

d i v a l e n t r a r e e a r t h s t r a n s f e r q u i t e r e a d i l y to t h e LiCl but t h a t h i g h L i C l flow r a t e s a r e r e q u i r e d t o a c h i e v e removal o f t h e t r i v a l e n t r a r e

earths,

The o v e r a l l e f f e c t o f t h e bismuth and L i C l flow rates on t h e

removal of r a r e - e a r t h f i s s i o n p r o d u c t s i s i l l u s t r a t e d i n F i g . 5.

i s s e e n t h a t t h e r e a c t o r performance i s r e l a t i v e l y i n s e n s i t i v e t o i n -

OWNL-DWG

- 70-2816

RATE = 33 ggrn

L 20

Fig. 3 . E f f e c t o f Rj.smuth Flow Rat,t: Through C o n t a c t o r s 1 aild 2 on t h e Rernoval Times of Neodymiurn and Samarium, Using t h e Metal T r a n s P e r Process ~

O R N L D W G 70-2817 1

BISMUTH FLOW RATlE~l12.3q p m

6( W ZI

0 U

G 5( -J

a > 0 I w a

Fig. 4. E f f e c t of L i C l Flow Hate on the Removal Times of Neodymiuni and Samarium, IJsing the Metal Transfer Process.

0.064

0,662

0.05

STAGES IN UP ES IN YRI S E S I N 81

-r T

-2

Pig. 5 . O v e r a l l E f f e c t of LiCl and Bismuth Flow Rates in the Metal T r a n s f e r System on MSBR Performance.

c r e a s e s i n t h e L i C l flow r a t e above 33 gpm.

A substantial increase i n

t h e b r e e d i n g g a i n ( b r e e d i n g r a t i o minus 1) i s o b t a i n e d by i n c r e a s i n g t h e bismuth f l o w r a t e from 8 . 3 gpm t o 1 2 . 4 gpm.

Further increases i n

t h e bismuth flow r a t e do n o t produce corresponding g a i n s i n r e a c t o r Bismluth and LiCl flow r a t e s o f 12.4 gpm and 33 gpm, r e -

performance.

s p e c t i v e l y , have been s e l e c t e d f o r t h e r e f e r e n c e p r o c e s s i n g c o n d i t i o n s Figure

6 shows t h e e f f e c t o f t h e number of s t a g e s i n t h e f u e l salt--

bismuth and t h e LiC1-bismuth c o n t a c t o r s

L i t t l e b e n e f i t i.s o b t a i n e d from

u s i n g more t h a n t h r e e s t a g e s ; t h e r e f o r e , t h r e e s t a g e s i s c o n s i d e r e d optimum.

Only one s t a g e i s r e q u i r e d t o e x t r a c t t h e t r i v a l e n t rare earths

from t h e L i C l i n c o n t a c t o r

The flow r a t e of t h e L i - U i

s o l u t i o n through

t h i s c o n t a c t o r i s 8 . 1 gpm, and 5.7 g a l o f t h e m e t a l stream must b e removed d a i l y t o prevent t h e s o l u b i l i t i e s o f t h e t r i v a l e n t r a r e e a r t h s i n t h e b i s muth from b e i n g exceeded. ing

The bismuth c a n b e r e c o v e r e d by h y d r o f l u o r i n a t -

o r h y d r o c h l o r i n a t i n g t h e metal s t r e a m i n t h e p r e s e n c e of s a l t , which

c a n b e processed f u r t h e r ( i f economical) o r d i s c a r d e d .

The d i v a l e n t rare

e a r t h s , p l u s s t r o n t i u m and barium, can be s t r i p p e d from t h e Li-CI. by p a s s i n g

2% of t h e L i C l (0.66 gpm) t h r o u g h a small two-stage e x t r a c t o r where it i s

contacted with

1 . 5 cm3 o f bismuth--50 a t . $ l i t h i u m p e r minute.

The b i s -

muth i n t h e metal stream c a n a g a i n b e r e c o v e r e d by h y d r o f l u o r i n a t i o n or h y d r o c h l o r i n a t i o n i n t h e p r e s e n c e o f a waste s a l t .

The r a r e - e a r t h removal

t i m e s t h a t can be obtained using t h e reference processing conditions

l.5 t o 50 days ( s e e Table

range from about Table 2.

2).

F i s s i o n Product Removal T i m e s f o r Metal T r a n s f e r P r o c e s s Under Reference Conditions

Element Ba

L a 3+

Removal 'Time (days 1

16.8 22.0

Nd3'

29.9

27.0

51.0

0.064

0,062

z a c3

0.062

- a.oa

w w

pr: 911

0.860

0.059

Fig. 6 . E f f e c t of t h e Numbel- of Stages in the F u e l S a l t - - B i s m u - t h and LiC1-Bismuth C o n t a c t o r s on MSBR Performance.

13 E f f e c t of Contamination of L i C l w i t h F l u o r i d e

2.3

The p r e s e n c e of f l u o r i d e i n t h e LiCl a c c e p t o r s a l t c a u s e s a s i g -

n i f i c a n t d e c r e a s e i n t h e thorium d i s t r i b u t i o n c o e f f i c i e n t , as shown i n Fig.

This r e s u l t s i n an i n c r e a s e i n t h e e x t e n t t o which t h e thorium

t r a n s f e r s to t h e L i C l and i s u i i d e s i r a b l e s i n c e t h e thorium i s subsequently e x t r a c t e d , a l o n g w i t h r a r e e a r t h s , from t h e LiCl i n t o t h e L i - B i

and i s discarited.,

solutions

As shown i n F i g , 8 , t h e thorium l o s s r a t e i n c r e a s e s

from 0.41 molelday w i t h no f l u o r i d e i n t h e LiCL t o 280 moles/day when t h e

L i C l c o n t a i n s 5 mole

% LiF.

It i s l i k e l y t h a t t h e f l u o r i d e c o n c e n t r a t i o n

i n t h e LiCl w i l l have t o be k e p t below about 2 mole

t o a thorium t r a n s f e r r a t e of 7.7 moles/day.

which corresponds

Discard of thorium a t t h i s

r a t e would add 0.0013 mill/kWhr t o t h e f u e l c y c l e c o s t .

The e f f e c t o f

t h e p r e s e n c e o f f l u o r i d e i n t h e L i C l on t h e removal o f rare e a r t h s i s n e g l i g i b l e ; i n f a c t , t h e r a r e - e a r t h removal e f f i c i e n c y i n c r e a s e s s l i g h t l y

as t h e f l u o r i d e c o n c e n t r a t i o n i n t h e L i C l i n c r e a s e s ,

3. AXIAL DISPERSION IN OPEN BUBBLE COLUMNS J.

S. Watson

L. E. McNeese

Axial d i s p e r s i o n i s i m p o r t a n t i n t h e desigi-i and performance o f con-

tinuous fluorinators.

S i n c e molten s a l t s a t u r a t e d w i t h f l u o r i n e i s cor-

r o s i v e , f l u o r i n a t o r s w i l l b e s i m p l e , open vessels t h a t have a p r o t e c t i v e l a y e r of f r o z e n s a l t on a l l exposed m e t a l s u r f a c e s .

I n such systems,

t h e r i s i n g gas b u b b l e s may c a u s e a p p r e c i a b l e a x i a l d i s p e r s i o n i n the

salt,

We have been i n v o l v e d , for some t i m e , i n a program f o r measuring

axial d i s p e r s i o n d u r i n g t h e c o u n t e r c u r r e n t flow of a i r and water i n open bubble columns.

The o b j e c t i v e s of t h i s p r o g r m are t o evaluate tile e f f e c t

of a x i a l d i s p e r s i o n on f l u o r i n a t o r performance and t o acco1.int for t h i s e f f e c t in t h e d e s i g n o f f l u o r i n a t o r s .

The d a t a r e p o r t e d i n t h i s s e c t i o n r e s u l t largely f r o m a s t u d y by

A . A. J e j e and C. R . Bozzuto,)' o f t h e MIT P r a c t i c e School, who i n v e s t i -

O R N L DWG 70-10,995

200 I00

50 )r

-0

u) 0)

a fx I-

3 "

0 I

2 TEMPERATURE=64O9C Th CONC IN Bi=90% OF Th SOLUBILITY AT 64OoC STAGES IN UPPER COLUMNS=3 STAGES IN DIVALENT STRIPPER=2 STAGES IN TRIVALENT STRIPPER= 1

0.5 0.3

0.00

0.01

0.02

0.03

0.04

0.05

MOLE FRACTION Li F

Fig. 8. E f f e c t of L i F Contaminant i n L i C l on Thorium Loss Rate i n Metal Transfer P r o c e s s .

g a t e d t h e e f f e c t s of gas i n l e t diamrmetel' aml. column diameter on axial d i s p e r s i o n i n open bubble columns d u r i n g t h e c o u n t e r c u r r e n t flow of a i r and w a t e r .

3.1

P r e v i o u s S t u d i e s on Axial D i s p e r s i o n

I n i t i a l s t u d i e s on axial d i s p e r s i o n i n open columns were c a r r i e d

out by B a u t i s t a and McNeese,'

who s t u d i e d axial. d i s p e r s i o n d u r i n g t h e

c o u n t e r c u r r e n t flow of a i r and water i n a 2-in.-iD, Two r e g i o n s of o p e r a t i o n were observed.

72-in.-long column.

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

of a "bubbly" regi-on, a t low g a s flow r a t e s , i.n which t h e a i r moved up

t h e column as i n d i v i d u a l bubbles and coal.escence w a s minimal.

The

second r e g i o n c o n s i s t e d o f a "slugging" r e g i o n , a t h i g h e r gas f l o w r a t e s , i n which t h e ai.r c o a l e s c e d r a p i d l y i n t o bubbles having d i a m e t e r s e q u a l t o

t h e column d i a m e t e r .

A p l o t of t h e 1ogariLhm of t h e d i s p e r s i o n c o e f f i -

c i e n t v s t h e I . o g a r i . t h of t h e gas flow r a t e w a s l i n e a r i n b o t h r e g i o n s . However, t h e s l o p e o f t h e l i n e r e p r e s e n t i n g d a t a i n the slugging regi-on

was h i g h e r t h a n t h a t f o r data. i n t h e bubbly r e g i o n .

The t r a n s i t i o n be-

tween t h e two r e g i o n s was well. d e f i n e d .

The same col.i.una and equipment were used by A. M. Sheikh and J . D.

Dearth,

5 of t h e MIT P r a c t i c e School, f o r i n v e s t i g a t i n g t h e e f f e c t s of

t h e v i - s c o s i t y and. t h e s u r f a c e t e n s i o n o f t h e l i q u i d .

The d i s p e r s i o n

c o e f f i c i e n t was found t o d e c r e a s e i n t h e bubbly r e g i o n a s t h e v i s c o s i t y

of t h e l i q u i d was i n c r e a s e d from 1 t o 1'5 cP by t h e a d d i t i o n of glycerol.

t o t h e w a t e r ; l i t t l e e f f e c t was noted in t h e sluggi.ng r e g i o n .

A n i.n-

c r e a s e i n t h e d i s p e r s i o n c o e f f i c i e n t was observed as t h e s i i r f a c e t e n s i o n

o f t h e l i q u i d w a s d e c r e a s e d by t h e a d d i t i o n of n-butanol t o t h e water.

3.2

Equipment and Experimental Technique

'The equipment and t h e e x p e r i m e n t a l t e c h n i q u e used i n t h e study

d e s c r i b e d h e r e are t h e same as t h o s e used i n t h e p r e v i o u s s t u d i e s ; a d e t a i l e d d e s c r i p t i o n was gi veri p r e v i o u ~ l y . ~The t e c h n i q u e involved

c o n t i n u o u s l y i n j e c t i n g a t r a c e r s o l u t i o n ( c u p r i c n i t r a t e ) i n t o t h e bottom of t h e column and d e t e r m i n i n g t h e r e s u l t i n g s t e a d y - s t a t e t r a c e r concentra-

t i o n p r o f i l e at p o i n t s upstream a l o n g t h e column a x i s .

The t r a c e r concen-

t r a t i o n w a s measured a t each o f 20 sampling p o i n t s t h a t were e q u a l l y spaced (3.5 i n . a p a r t ) a l o n g t h e 72-in.-long

column.

A t each sampling

p o i n t , a m i n i a t u r e c e n t r i f u g a l pump was used for c i r c u l a t i n g s o l u t i o n between t h e column and a p h o t o c e l l for d e t e r m i n a t i o n OS t h e t r a c e r concentration.

The s o l u t i o n w a s withdrawn from, and r e t u r n e d t o , o p p o s i t e

s i d e s o f t h e column a t t h e sane e l e v a t i o n . Three column d i a m e t e r s (1.5, 2 , and 3 i n . I D ) and f o u r gas i n l e t

d i a m e t e r s (0.019, 0,04, 0~06, and 0.085 i n . ) were used by t h e MIT'

L a t e r , measurements were a l s o made w i t h a 0.17-

P r a c t i c e School group. in.-ID gas i n l e t .

The f r a c t i o n o f t h e column volume occupied by t h e gas

phase d u r i n g t h e c o u n t e r c u r r e n t flow of a i r and water w a s measured by two different techniques,

The f i r s t c o n s i s t e d of measuring (1) t h e h e i g h t of

t h e air-water m i x t u r e above t h e a i r i n l e t w h i l e a i r was f l o w i n g through

t h e column, and ( 2 ) t h e h e i g h t of t h e water above t h e g a s i n l e t a f t e r t h e a i r flow w a 5 t u r n e d o f f .

The g a s holdup w a s t h e n determined from t h e

difference i n these values.

The second t e c h n i q u e c o n s i s t e d of a t t a c h i n g

a w a t e r - f i l l e d manometer t o p o i n t s a l o n g t h e column a x i s .

The manometer

r e a d i n g i n d i c a t e d t h e s e t t l e d h e i g h t of l i q u i d above t h e p o i n t o f a t t a c h -

ment.

The second method w a s found t o b e more r a p i d , and also allowed holdup

measurements t o b e made f o r upper p o r t i o n s o f t h e column.

3.3

E f f e c t s o f Gas I n l e t Diameter and Column Diameter on Axial D i s p e r s i o n

A s shown i n Fig. 9, t h e d i s p e r s i o n c o e f f i c i e n t v a l u e s measured f o r a 2-in.-diam column are not dependent, on gas i n l e t d i a m e t e r i n eitheir

t h e s l u g g i n g r e g i o n o r t h e bubbly r e g i o n .

using t h e 1 . 5 - and 3-in.-diam

A- f e w t e s t s were also made

columns w i t h a O.L7-in.-dim

no e f f e c t of gas i n l e t d i a m e t e r w a s noted.

gas i n l e t ;

Fig. 9. Effects of Gas FI.OTJ Raie and O r i f i c e Diameter Dispersion i n a 2-in.-dim. Open Column.

011

Axial

It i s n o t s u r p r i s i n g t h a t changes i n t h e g a s i n l e t diameter have no e f f e c t i n t h e s l u g g i n g r e g i o n s i n c e a g r e a t d e a l of c o a l e s c e n c e o c c u r s i n t h i s r e g i o n and t h e bubble s i z e d i s t r i b u t i o n q u i c k l y becomes independ-

e n t of t h e i n i t i a l s i z e d i s t r i b u t i o n . gas flow r a t e s ) , where c o a l e s c e n c e

i n l e t d i m e t e r might be i m p o r t a n t ,

However, i n t h e bubbly r e g i o n (low

i s minimal, it w a s thought t h a t g a s

It has been p o s t u l a t e d

4 that

"chain

bubbling" o c c u r s a t low gas f l o v rates ( i a e e ,t h a t gas bubbles are n o t formed c o n s e c u t i v e l y ) .

I n t h i s c a s e , t h e bubble diameter would n o t be

h i g h l y dependent on g a s i n l e t d i a m e t e r .

Even w i t h d i f f e r e n t bubble diam-

e t e r s , one would n o t expect l a r g e d i f f e r e n c e s i n bubble r i s e v e l o c i t i e s

or, p o s s i b l y , l a r g e changes i n d i s p e r s i o n c o e f f i c i e n t .

a Taylor

Bavies and

r e p o r t t h a t t h e bubble r i s e v e l o c i t y i s p r o p o r t i o n a l t o t h e s i x t h

r o o t of t h e bubble volume.

Thus, even f o r c o n d i t i o n s r e s u l t i n g i n t h e

r e l e a s e of" s i n g l e bubbles (where bubble volume i s p r o p o r t i o n a l t o t h e cube r o o t o f t h e i n l e t d i a m e t e r ) , one would f i n d l i t t l e v a r i a t i o n i n

r i s e v e l o c i t i e s and, p o s s i b l y , l i t t l e v a r i a t i o n i n d i s p e r s i o n c o e f f i c i e n t w i t h changes i n gas i n L e t d i a m e t e r . The e f f e c t s of g a s flow rate and column diameter are shown i n F i g .

10 f o r column d i a m e t e r s o f 1 . 5 , 2 , and 3 i n .

I n t h e slugging region,

there i s l i t t l e difference i n dispersion coefficient f o r t h e three column d i a m e t e r s a t a g i v e n volumetric gas flow r a t e .

However, t h e d a t a

do not e x t e n d t o h i g h gas flow rates f o r a l l column d i a m e t e r s , and

e x t r a p o l a t i o n t o h i g h e r g a s flow rates i s q u e s t i o n a b l e s i n c e uncer-

t a i n t y i n t h e d a t a i s g r e a t e s t a t h i g h g a s flow r a t e s .

T'ne d i s p e r s i o n c o e f f i c i e n t s f o r t h e 2-in.do n o t d i f f e r a p p r e c i a b l y i n t h e bubbly r e g i o n .

and S-in.-dianl

colurnns

On t h e o t h e r band, d a t a

from t h e l 0 5 - i n . - d i a m column show s i g n i f i c a n t l y lower v a l u e s f o r t h e d i s -

p e r s i o n c o e f f i c i e n t and a g r e a t e r dependence o f d i s p e r s i o n c o e f f i c i e n t on gas flow r a t e i n t h i s r e g i o n .

3.4

Gas Hol-dup i n Bubble Columns

E x p e r i m e n t a l l y determined gas holdup v a l u e s are summarized i n F i g . 11, which s h o w s t h e e f f e c t s of s u p e r f i c i a l gas v e l o c i t y and col-urnn d i m e t e r

dnQ1OH SW9

22 A t low gas flow r a t e s

on holdup.

holdup i s l i n e a r l y dependent on super-

f i c i a l gas v e l o c i t y and i s independent o f column di.miieter.

However, a

t r a n s i i i o n from t h i s behavior i s observed a t a s u p e r f i c i a l gas v e l o c i t y of 2 t o 3 cm/sec.

A t s u p e r f i c i a l v e l o c i t i e s above t h e t r a n s i t i o n , .the

holdup d a t a f o r t h e v a r i o u s coliljian d i a m e t e r s d i v e r g e ; t h e holdup i s g r e a t e s t f o r t h e smallest col.uutrn d i a m e t e r . wxln

Data f o r t h e 3-in.-diam

col-

do not extend, beyond the t r a n s i t i o n r e g i o n .

The t r a n s i t i o n region corresponds roughly to t h e t r a n s i t i o n between

bubbly and s l u g flow, as d e t e m i n e d from measurements of t h e d i s p e r s i o n coefficient.

Values f o r holdup i n t h e t r a n s i - t i o n r e g i o n a r e thought t o

b e i n a c c u r a t e and w i l l be checked d u r i n g f u t u r e s t u d i e s . 'There w a s no d e t e c t a b l e v a r i a t i o n o f holdup w i t h axial p o s i t i o n

along the coluiiin for any operati.ng c o n d i t i o n s t e s t e d .

3.5

D i s c u s s i o n of Results and F'l-Lture Experiments

Although t h e p r e s e n t d a t a on a x i a l d i s p e r s i o n are incomplete, one can m a k e t h e f o l l o w i n g t e n t a t i v e c o n c l u s i o n s :

(I) I n t h e slugging r e Z i o n , t h e dispersion c o e f f i c i e n t appears t o be p r o p o r t i o n a l t o t h e square r o o t of t h c v o l u m e t r i c g a s flow r a t e and independent of column dimnetex-. (2)

I n tlie bubbly r e g i o n , t h e d i s p e r s i o i i c o e f f i c i e n t is o n l y a functj-on o f t h e v o l u m e t r i c gas Tbow r a t e f o r colunns t h a t are 2 i n . o r l a r g e r i n d i a m e t e r .

d a t a f o r a 1.5-in.-diam

The d i s p e r s i o n c o e f f i c i e n t

colwnii d e v i a t e from t h i s c o n d i t i o n .

A d d i t i o n a l i n f o r m a t i o n i s needed i n o r d e r t o confirm Lhese conclusions.

The r e p o r t e d d a t a become l e s s a c c u r a t e as t h e c o l i m diameter

i s increased

s i n c e a i r , which c a l l e c t s i n t h e p h o t o c e l l s m p l e c i r c u i t s ,

p r e v e n t s flow t h r o u g h t h e p h o t o c e l l s .

W e will c o n s i d e r methods f o r

p r e v e n t i n g t h c b u i l d u p of a i r i n t h e sample c i r c u i t s as w e l l as alLei*n a t i v e methods f o r measuring d i s p e r s i o n c o e f f i c i e n t s .

Future s t u d i e s w i l l b e concerned p r i m a r i l y w i t h o b t a i n i n g d a t a i n t h e r e g i o n of s l u g g i n g f l o w , where c o n t i n u o u s f l u o r i n a t o r s of i n t e r e s t w i l l operate.

Gas i n l e t s o t h e r t h a n t h e small-diameter t u b e s used t h u s

far w i l l b e s t u d i e d .

Most of t h e e f f o r t w i l l b e c o n c e n t r a t e d on s i d e

i n l e t s of l a r g e d i a m e t e r s i n c e t h i s t y p e of i n l e t a p p e a r s t o be t h e most amenable t o p r o t e c t i o n a g a i n s t c o r r o s i o n by u s e of a f r o z e n w a l l .

4. CONSIDERATIONS

OF CONTINLJOIJS FLUORIN4TORS AND THEIR APPLICABILITY TO MSBR PROCESSING

L. E , McNeese

J. S. Watson

9-12 Most o f t h e f l o w s h e e t s considesed t o d a t e f o r p r o c e s s i n g MSBR

f u e l s a l t r e q u i r e f l u o r i n a t i o n of molten s a l t f o r removal of uranium s;t one o r more p o i n t s .

These a p p l i c a t i o n s i n c l u d e :

(1)removal o f t r a c e

q u a n t i t i e s o f uranium from r e l a t i v e l y s m a l l s a l t streams p r i o r t o d i s c a r d , ( 2 ) removal of uranium from a c a p t i v e s a l t volume i n which 233Pa

i s accumulated and h e l d f o r decay t o 233U,

( 3 ) removal o f most o f t h e

uranium from r e l a t i v e l y l a r g e f u e l s a l t streams p r i o r t o i s o l a t i o n of p r o t a c t i n i u m and removal o f r a r e e a r t h s , and

(4) n e a r l y

removal of uraniwn from a s a l t stream c o n t a i n i n g ap''*

produce i s o t o p i c a l l y pure 233U.

quantitative

i n order t o

Not a l l o f t h e s e a p p l i c a t i o n s r e q u i r e

continuous f l u o r i n a t o r s ; i n f a c t , t h e u s e o f b a t c h f l u o s i n a t o s s r e s u l t s i n d e f i n i t e advantages i n c e r t a i n c a s e s ,

However, as t h e q u a n t i t i e s

of s a l t and uranium t o be handled i n c r e a s e , t h e use o f continuous f l u o r i n a t o r s becomes mandatory i n o r d e r t o avoid u n d e s i r a b l y l a r g e invent o r y c h a r g e s on uranium and molten s a l t as w e l l as t h e d e t r i m e n t a l increase i n r e a c t o r doubling time t h a t i s associated with an increased f i s s i Le i n v e n t o r y

Although t h e l i t e r a t u r e c o n t a i n s many r e f e r e n c e s t o t h e removal of

uranium from molten s a l t by b a t c h f l u o r i n a t i o n , i n f o r m a t i o n on continuous f l u o r i n a t o r s , p a r t f c u l a r l y on fluorinators capable of h a n d l i n g s a l t

flow r a t e s on t h e o r d e r of 1 0 0 f t /day, i s r a t h e r meager,

The remainder

24 of t h i s s e c t i o n i s devoted t o a review of t h e e x p e r i e n c e w i t h f l u oi-inators, a discussion of the p o s s i b l e types of f l u o - r i n a t o ~ s a ~

mathematical a n a l y s i s of open-column continuous f l u o r i n a t o r s , and p r e d i c t i o n s of the p e r f ormaiic e of open-colinm contiiiiioiis f l u o r i u a t o r s f o r MSBH p r o c e s s i a g a p p l i c a t i o m .

4.1

Type'; of F l u o r i n a t o r s

NG known materials o f c o n s t r u c t i o n are r e s i s t a n t t o a t t a c k by t h e

extremely c o r r o s i v e enviromien-t; r e s u l t i n g from t h e combined a c t i o n o f f o r t h i s r e a s o n , any d i s c u s s i o n of f l u -

f l u o r i n e and iiioIten

o r i n a t o r t y p e s must a l s o g i v e c o n s i d e r a t i o n t o t h e r e l a t i v e ease of p r o t e c t i n g t h e f l u o r i n a t o r from c o r r o s i o n .

S e v e r a l t y p e s of f l u o r i -

iiators, a l l of which can b e c l a s s i f i e d as e i t h e r b a t c h o r c o n t i n u o u s , have been c o n s i d e r e d i n t h e p a s t . sal:t

I n a b a t c h f l u o r i n a t o r . , t h e mol.ten

i s c o n t a c t e d with f l ? i o % i n e f o r a s u f f i c i e n t time to reduce t h e

ursniun concentration t o t h e desired level.

A batch fluorinator i s

e s p e c i a l l y useful. i.n c a s e s where it i s d e s i r e d t o remove small ciiiant i t i e s nT uranium from molten s a l t p r i o r t o i t s d . i s c a r d . operations

I n ha-tch

t h e salt c a n be analyzed r e p e a t e d l y and the p r o b a b i l i t y

o f i n a d v e r t e n t d i s c a r d of f i s s i l e m a t e r i a l . can be reduced t o an acceptably l o w level.

However, Lhis t y p e o f f l u o r i n a t o r i s n o t well.

s u t t e d t o t h e removal o f l a r g e q u a n t i t i e s of uranium from s a l t s t r e a m s

having flow r a t e s of 50 f t 3 /day o r g r e a t e r u n l e s s one can t o l e r a t e t h e l a r g e s a l t and uranium i n v e n t o r i e s t h a t r e s u l t .

Batch f l u o r i . n a t o r s are amenable t o p r o t e c t i o n a g a i n s t corrosjon by

use of a f r o z e n w a l . 1 , provided t h e h e a t g e n e r a t i o n r a t e i n tile sal.1; i s

a.deq1.mt.e f o r s u p p o r t i n g t h e t h e r m a l g r a d i e n t n e c e s s a r y f o r m a i n t a i n i n g a l a y e r of f r o z e n salt a d j a c e n t t o molten s a l t .

I n t h i s method o f cor-

r o s i o n p r o t e c t i o n , a l a y e r of f r o z e n s a l t is maintained on a l l metal s u r f a c e s t h a t a r e expected t o b e c o n t a c t e d by molten s a l t .

t h e b u i l d u p o f a p r o t e c t i v e NiF solved by t h e molten salt,.

This allows

l a y e r , which would o-therwise b e d i s -

A t l e a s t t h r e e t y p e s of c o n t i n u o u s f l u o r i n a t o r s have 'been con-

(1)open columns i n which a n a p p r e c i a b l e

sidered i n t h e past; these are:

axial uranium c o n c e n t r a t i o n g r a d i e n t e x i s t s , ( 2 ) a series of well-mixed

vessels, and ( 3 ) f a l l i n g - d r o p f l u o r i n a t o r s i n which molten s a l t d r o p l e t s a r e allowed t o f a l l through a gas phase c o n t a i n i n g f l u o r i n e .

1 4 Open-

column continuous f l u o r i n a t o r s have t h e advantage of a r e l a t i v e l y s m a l l

s a l t holdup and hence a low uranium i n v e n t o r y . T h i s t y p e o f f l u o r i n a t o r , vll.-.:k ' C*-I-:.,+,S of a simple open c y l i n d e r , can b e designed f o r frozen-wall

TTlr

p r o t e e t i m a g a i n s t c o r r o s i o n f o r a f a i r l y wide range of s p e c i f i c h e a t

A l s o , i t a p p e a r s t o b e c a p a b l e of a

g e n e r a t i o n rat,es i n t h e s a l t .

r e l a t i v e l y h i g h s a l t throughput w i t h a low s a l t i n v e n t o r y .

However,

t h i s t y p e of c o n t a c t o r depends on t h e e s t a b l i s h m e n t of a s i g n i f i c a n t s t x i a l uranium c o n c e n t r a t i o n g r a d i e n t ; f o r t h i s r e a s o n , axial d i s p e r s i o n i n t h e s a l t phase i s i m p o r t a n t .

Many o f t h e same arguments a p p l y t o a

c o n t i n u o u s f l u o r i n a t o r c o n s i s t i n g of a s e r i e s of well-mixed v e s s e l s . The s a l t i n v e n t o r y i n such a system i s l i k e l y t o b e l a r g e r t h a n i n t h e c a s e of an open-column f l u o r i n a t o r designed f o r a g i v e n s a l t t h r o u g h p u t . N o a t t e m p t would be made t o minimize d i s p e r s i o n i n t h e s a l t phase i n a

given v e s s e l .

Protection of t h e intervessel salt t r a n s f e r l i n e s against

c o r r o s i o n f o r t h i s t y p e of f l u o r i n a t o r might be d i f f i c u l t . The f a l l i n g - d r o p f l u o r i n a t o r a p p e a r s t o have s e v e r a l advantages over o t h e r t y p e s of continuous f l u o r i n a t o r s .

For example, t h e s a l t

i n v e n t o r y i s q u i t e l o w , and a l a r g e q u a n t i t y of gas c a n b e c o n t a c t e d with a small, mount of s a l t ,

On t h e o t h e r hand, t h i s system has two

d i s a d v a n t a g e s t h a t have n o t p r e s e n t l y been circumvented:

(1)t h e r m a l

c o n v e c t i o n c u r r e n t s i n t h e g a s t e n d t o sweep t h e molten s a l t d r o p l e t s i n t o t h e fluorinator w a l l , resulting i n a highly corrosive condition, and (2) t h e d e v i c e used f o r d i s p e r s i n g t h e s a l t i n t o s m a l l d r o p l e t s i s subject t o corrosion.

It appears t h a t t h e open column i s t h e best t y p e of continuous f l u o r i n s t o r f o r MSBR processing a p p l f c a t i o n s r e q u i r i n g removal of 50 t o

99% of t h e uranium from s a l t streams t h a t have flow rates on the o r d e r o f 100 f t 3/day; t h u s t h i s f l u o r i n a t o r has been s e l e c t e d f o r f u r t h e r development.

26 4.2 Experience R e l a t e d t o Fhiori.niztion o f Molten S a l t f o r Uranium iiemoval

The removal. o f uranium from molten f l u o r i d e s a l t s by b a t c h f l u o r i n a t i o n has been s t u d i e d e x t e n s i v e l y i n t h e l a b o r a t o r y ,

1.5

i n engineering

experiments ,16 and i n t h e OlWL Fused S a l t F l u o r i d e v o l a t i l i t y P r o c e s s Pilot Plant.

S e v e r a l spe-(it r e a c t o r f u e l s cooled f o r p e r i o d s as s h o r t

as 25 days were used i n these s t u d i e s .

17,1.8

t i o n s o f b a t c h f l u o r i n a t i o n c o n s i s t of:

kg o f uranium from 74 ft'

The most r e c e n t demoristra-

(1) t h e r e c o v e r y of zb0u.t

o f MSRE f l u s h s a l t (66-311 mole

6.5

) 2 o p e r a t i o n , which r e s u l t e d i n a f i n a l uranium concentra-

d u r i n g a 6.6-hr

LiF-BeF

t i o n of 7 ppm i n t h e sal.t,19 and ( 2 ) t h e r e c o v e r y o f about 214 kg of

'74 ft'3 of MSRE f u e l s a l t (65-30-5 mole % LiF-BeF2-ZrFq) d u r i n g a 6-day o p e r a t i o n ( t l - u o r l n a t i o n time 47 hr), which r e s u l t e d i n a f i n a l uranium c o n c e n t r a t i o n of 26 ppm i n t h e s a l t . 19

uranium from

Data o b t a i n e d from t h e above systems demonstrate t h a t t h e concentra-

t i o n o f uranium i n mol.ten salt can be d e c r e a s e d lay b a t c h f l u o r i n a t i o n t o

v e r y low l e v e l s .

Although t h e e q u i l i b r i a involved have n o t been mea:;ured,

t h e f o r m a t i o n of UF

i s strongly favored.

It i s b e l i e v e d t h a t t h e iura,nium

c o n c e n t r a t i o n i n molten s a l t i n equi.librium w i t h F -UF m i x t u r e s c o n t a i a -

i n g low c o n c e n t r a t i o n s of f l u o r i n e i s v e r y low; f o r t h e p r e s e n t d a t a , i.t, i s i . i i i s t i n g u i s h a S l e from z e r o .

Experience w i t h continuous f l u o r i n a t i o n i s l i m i t e d t o a s i n g l e 3-tudy by McNeese. 2o

The f l u o r i n a t m used i n t h i s s t u d y had a s a l t d e p t h of 48

i n . and. was c o n s t r u c t e d from I - i n . - d i m

(nominal) n i c k e l p i p e .

No a t t e m p t

was made t o p r o t e c t t h e f l u o r i n a t o r w a l l - s from c o r r o s i o n , and a r e l a t i v e l y

high corrosion r a t e occurred.

The uranium removal e f f i c i e n c y wits d e t e r -

mined by a n a l y z i n g t h e i n l e t and o u t l e t s a l t streams.

The f l u o r i n e

u t i l i z a t i o n c o u l d n o t b e determined because of t h e h i g h corrosion rate.

~ ) two i n l e t uraniim c o n c e n t r a t i o n s 'Pwo t e m p e r a t u r e s ( 5 2 5 and 6 0 0 ~ and i n t h e sa1.t (0.12 and 0 . 3 5 mole % ) were u s e d .

are si-marized i n Fig. 12.

The r e s u l t s of t h i s s t u d y

-4

r P-

0.3

t I

UF,

CONC IN

FEED SALT (mole % )

0.35

TEMPERATURE ("C) 52 5

600 600

50 io0 200 SALT THROUGHPUT ( g - m o l e s / h r )

500

4000

F i g . 12. V a r i a t i o n of t h e R e s i d u a l Uranium with Salt 31'10~Rate, Temperature, and I n l e t TJraniim Concentrat i o n During the Continuous Fluorinat i o n of Molten Salt.

Three runs f o r each temperatux e and i n l e t uranium c o n c e n t r a t i o n

( a t o t a l - o f n i n e r u n s ) were made u s i n g a Yange of s a l t flow r a t e s .

The

f r a c t i o n o f t h e u r a n i i m r e n o w d was h i g h i n a l l c a s e s , ranging from 97.5

t o almost 99.9%.

T h e f l u o r i n a t i o n r a t e (and hence the f r a c t i o n o f t h e

ixaniwn removed) i ncreased a s t h e t e m p e r a t u r e was i n c r e a s e d ; the f r a c t i o n of t h e uranium removed d e c r e a s e d as t h e i n l e t uranium c o n c e n t r a t i o n vas

decreased.

These d a t a s e r v e p r i m a r i l y t o demonstrate t h a t high uranium

removal e f P i c i e n c i e s c m 5e o b t a i n e d w i t h an open-column continuous â&#x201A;Źluorin&tor.

However, t h e y are s u f f i c i e n t l y yeliable f o r use w i t h d a t a

on a x i a l d i s p e r s i o n i n open columns t o a l l o w e s t i m a t i n g t h e prSorrnance o f 1 a r g e r f l u o r i n a t o r s , which are r e q u i r e d f o r

MSBR p r o c e s s i n g .

A s t u d y has a l s o been made of t h e hydrodynamics o f h e a t t r a n s f e r i n

a s i m u l a t e d open-column continuous f l u o r i n a t o r having a. f r o z e n wall as 2 1. a means o f p r o t e c t i o n a g a i n s t c o r r o s i o n . The equipment c o n s i s t e d of a 5-in.-diam,

8-fb-long p i p e i n which molten s a l t

and argon were c o u n t e r c u r r e n t l y c o n t a c t e d .

(66-34 mole $

T,iF-ZrFIL)

A voluneti-fc h e a t s o u r c e i n

t h e m o l t e n s a l t w a s s i m u l a t e d by Calrod h e a t e r s l o c a t e d aJ.ong t h e c e n t e r l i n e of t h e p i p e , and p r o v i s i o n w a s made f o r c o a l i n g t h e p i p e w a l l . systein w a s

operated over

The

r a n g e of c o n d i t i o n s t h a t i n c l u d e d h e a t genera-.

3 , which i s g r e a t e r

t i o n ra,t,es i n t h e molten s z l t as h i g h 8s 55.7 kW/ft'

t h a n t h e h e a t g e n e r a t i o n r a t e in salt j u s t removed from t h e r e f e r e n c e 1000-MkJ(e) MSBX.

The t h i c k n e s s of t h e f r o z e n s a l t f i l m on t h e f l u o r j - n a t o r

wall ranged from 0 . 3 t o 0 . 8 i n . , depending on t h e o p e r a t i n g c o n d i t i o n s . Tine f i l m w a s syminetrical and adhered t o t h e metal wall.

4.3

Mathematical A n a l y s i s of Gpen-Column Cont iniious F l u o r i n a t o r s

Consider a d i f f e r e n t i a l h e i g h t oâ&#x201A;Ź a continimus f l u o r i n a t o r i n which

f l u o r i n e atid molten s a l t c o n t a i n i n g uranium are i n c o u n t e r c u r r e n t flow. I f the r a t e of removal of uranium from t h e salt, i s assumed t o be f i r s t

o r d e r w i t h r e s p e c t t o t h e uranium c o n c e n t r a t i o n i n t h e salt, a m a t e r i a l

ba1.ance

011

t h e d i f f e r e n t i a l volume y i e l d s t h z r e l a t i o n C - - k CdC n -d-Z V =Q, dX2

29 where

2 D = axial d i s p e r s i o n c o e f f i c i e n t , em / s e c , C = c o n c e n t r a t i o n of

uranium i n s a l t , moles/cm

X = p o s i t i o n i n column measured from t o p o f column, em,

= s u p e r f i c i a l s a l t v e l o c i t y , cmlsec,

k = r e a c t i o n rat,e c o n s t a n t , see

-1

The terms i n Eq. (1) r e p r e s e n t t h e t r a n s f e r of uranium i n t h e s a l t by

axial diffusion, t h e t r a n s f e r o f urslnium i n t h e s a l t by c o n v e c t i o n , and

t h e removal of uranium from t h e s a l t by r e a c t i o n w i t h f l u o r i n e , respecThe assumption o f a f i r s t - o r d e r r e a c t i o n does not imply a

tively,

p a x t i c u l a r r a t e - l i m i t i n g r e a c t i o n mechanism; however, it i s c o n s i s t e n t w i t h t h e assumption t h a t t h e r a t e - l i m i t i n g s t e p i s d i f f u s i o n o f uranium i n t h e salt t o t h e gas-liquid i n t e r f a c e ,

I n t h i s case, t h e first-order

e x p r e s s i o n would imply t h a t t h e c o n c e n t r a t i o n o f uranium i n t h e s a l t

a t t h e f n t e r f a c e i s n e g l i g i b l e i n comparison w i t h t h e uranium concentrat i o n i n t h e s a l t a t p o i n t s a s h o r t d i s t a n c e from t h e i n t e r f a c e . The boundary c o n d i t i o n s chosen â&#x201A;Źor u s e w i t h Eq. (1)a s s m e t h a t t h e d i f f u s i v e flux a c r o s s t h e f l u o r i n a t o r b o u n d a r i e s i s n e g l i g i b l e :

( t o p of f l u o r i n a t o r ) ,

and a t ?z = R (bottom o f f l u o r i n a t o r ) ,

where â&#x20AC;&#x2DC;feed

Co+

= c o n c e n t r a t i o n of uranium i n s a l t f e d t o t h e f l u o r i n a t o r , = c o n c e n t r a t i o n o f uranium i n s a l t a t t h e t o p o f t h e f l u -

orinator.

30 Note t h a t Co+ i.s n o t eqim:i L o C

feed s i n c e t h e y e i s a d j - s c o n t i n u i t y i n uranium concentratj-on i n t h e s a l t a t t h e top of the col.imn where the salt enters.

The s o l u t i o n t o Eq. (1)w i t h t h e s t a t e d boundary c o n d i t i o n s i s , then I

where a i s d e f i n e d as V/2D, B i s d e f i n e d as /V2

I- 4kD/2'D,

and the r a t i o

of t h e uranium c o n c e n t r a t i o n i n s d t ~ . e a v i n gt h e c 0 1 . m ( a t

= 2) t o

t h e concentration i n the feed salt i s :

wh eT e

4,4

E v a l u a t i o n of F l u o r i n a t i o n Reaction Rate Constant

A p p l i c a t i o n OS E q . ( 5 ) t o t h e d e s i g n and e v a l u a t i o n of con-tiriuous f l u o r i n a t o r s r e q u i y e s i n f o r m a t i o n on t h e rate c o n s t a n t k and t h e a x i a l

d i s p e r s i o n c o e f f i c i e n t D.

Values f o r t h e d i s p e r s i o n c o e f f i c i e n t can be

o b t a i n e d from studies i n which a i r and water were c o n t w t e d c o u n t e r c u r r e n t l y i n open bubble ~ 0 l - s . ~

i n F i g . 13 f o r 1.5-, 2-,

Results from these s t u d i e s a r e shown

and 3-in.-ID

columns t h a t were 7 2 i n . long.

The d i s p e r s i o n c o e f f i c i e n t i s independent of t h e gas i n l e t diameter

over t h e range t e s t e d (from 0.020 t o 0.l'lO i n . ) and appears t o be es-

2 3 J

I I

32 s e n t i a l l y independent o f colunr). d i - m e t e r Cor tile I.a.t-ger column s i z e s , Only w i t h t h e smallest, column diameter a:nd low g a s r a t e s d i d t h e d a t a d e v i a t e from a s i n g l e curve.

Under a3.1 o t h e r c o n d i t i o n s , t h e d i - s p e r s i o n

c o e f r i c i e n t a p p e a r s t o be a f i n e t i o i l o f t h e v o l u m e t r i c gas flow r a t e r a t h e r t h a n t h e s u p e r f i c i a l gas v e l o c i t y as one might e x p e c t .

The da-La

fall. i n t o two r e g i o n s , corresponding t o low gas flow rates and t o high gas flow r a t e s , r e s p e c t i v e l y .

'l'he experimental d a t a from which t h e r a t e

c o n s t a n t k w a s e v a l u a t e & were used w i t h d a t a from t h e r e g i o n o f low gas flow r a t e s .

'The f l u o r i n a t o r s proposed f o r MSBR p r o c e s s i n g a r e expected

t o o p e r a t e i n tile r e g i o n of high gas t l o w r a t e s , w e l l beyond t h e r a n g e of t h e e x i s t i n g data.

In analyz-ing t h e experimental d a t a from t h e l - i n . - d i m

open-column

continuous f l u o r i n a t o r , i t w a s assumed t h e a x i a l d i s p e r s i o n c o e f f i c i e n t s were t h e same as t h o s e measured i n a 1-1/2-in.-diam coliunn s i z e t e s t e d ) .

column ( t h e c l o s e s t

No c o r r e c t i o n w a s made f o r d j . r f e r e n c e s i n p h y s i c a l

p i - o p e r t i e s between molten s a l t and w a t e r ; f o r t h i s r e a s o n , c o n s i d e r a b l e

u n c e r t a i n t y may have been i n t r o d u c e d i n t o t h e resinl:t,s improve t h i s s i t u a t i o n a r e under way.

Efforts t o

A group of MIT P r a c t i c e School

s t u d e n t s has s-tudied t h e effects of v i s c o s i t y and attempted to determine

the e f f e c t of i n t e r f a c i a l t e n s i o n on t h e dispel-sion coeylicient.7 In-

creases i n v i s c o s i t y r e s u l t i n a decrease i n t h e dispersion c o e f f i c j e n t ; however, t h e e f f e c t s o f high i n t e r f a c i a l t e n s i o n and d e n s i t y of t h e l i q u i d a r e not known. Y'he r e a c t i o n r a t e c o n s t a n t k w a s e s t i m a t e d frcm t h e s e r i e s of c o n t i n -

uous f l u o r i n a t i o n experiments made by McNeese i n a 1 - i n . - d i m ,

148-in.-1ong

f l u o r i n a t o r by u s i n g t h e mathematical :model. developed above and an e s t i m a t e for the axial dispersion coefficient. ant1 0.12 mole % ) were s t u d i e d a t

w a s s t u d i e d a t 525OC.

6oo0c,

TWO i n l e t uranium composi:t,ions

(0.35

and one composition ( 0 . 3 5 mole % )

Three da.-La, p o i n t s corresponding t o d i f f e r e n t s a l t

flow rates were o b t a i n e d for each set, of t e m p e r a t u r e s and i n l e t composi-

tions.

The f l u o r i n e flow r a t e w a s d i f f e r e n t f o r each d a t a p o i n t ; however,

a c c o r d i n g t o t h e p r e s e n t model, t h i s flow r a t e o n l y a f f e c t s the T e s u l t s by changing t h e d i s p e r s i o n c o e f f i c i e n t .

To e v a l u a t e t h e r a t e c o n s t a n t ,

k , w e chose t o u s e t h e d a t a o b t a i n e d a t 525OC s i n c e t h e t e m p e r a t u r e o f

t h e molten s a l t i n t h e proposed f l u o r i n a t o r w i l l be 1 0 t o 15OC above

t h e s a l t l i q u i d u s t e m p e r a t u r e o f 505OC. A p p l i c a t i o n of t h e model t o

t h e t h r e e d a t a p o i n t s o b t a i n e d a t 525OC gave t h e r e s u l t s shown i n Table

Mote t h a t t h e r e s u l t i n g v a l u e s f o r k are r e a s o n a b l y c o n s t a n t and

show no t r e n d w i t h s a l t or f l u o r i n e f l o w r a t e .

Although t h e s e d a t a do

n o t confirm t h e v a l i d i t y o f t h e p r e s e n t model, t h e y do n o t c o n t r a d i c t t h e model. T a b l e 3. -

S a l t Flow Rate (crn/sec)

Summary of F l u o r i n a t i o n R e s u l t s Obtained a t 525째C C(k) 'feed

F2 Flow Rate (cm3/sec)

D (cm2/sec

k ( sec-'-

0 0625

0 0257

6.8

0.00814

0.0445

0 0096

5.0

0.01010

0 e 0225

0 e 00457

3.82

0.0091r3

avtz 0.00922

I n t h e mathematical model developed e a r l i e r , t h e e f f e c t o f axial d i s p e r s i o n w a s c o n s i d e r e d ; however, it i s i n t e r e s t i n g t o n o t e how t h e r e s u l t s are a f f e c t e d when a x i a l d i s p e r s i o n i s n e g l e c t e d .

The s o l u t i o n

t o Eq. ( I ) when D i s zero i s :

The t h r e e d a t a p o i n t s c o n s i d e r e d above produce K v a l u e s i n t h i s c a s e o f

O.oOl88, 0 00170, and O . O O O g 9 5 sec-l

The e f f e c t i v e rate c o n s t a n t s a r e ,

a s e x p e c t e d , c o n s i d e r a b l y lower t h a n Ynose o b t a i n e d when a x i a l d i s p e r s i o n i s taken i n t o account.

An i n d i c a t i o n t h a t a x i a l d i s p e r s i o n i s s i g n i f i c a n t

i n t h e p r e s e n t case l i e s i n t h e f a c t t h a t t h e l o w e s t K v a l u e w a s o b t a i n e d when t h e s a l t flow r a t e w a s lowest; t h e e f f e c t s o f axial d i s p e r s i o n would be t h e g r e a t e s t f o r t h i s c o n d i t i o n .

4.5

PredicLed. Performance of Open-Column Continuous F l u o r i n a t o r s

The performamce of large open-co1u.m

continuous f l u o r i n a t o r s was

e s t i m a t e d from En,. ( 5 ) u s i n g t h e p r e v i o u s l y d i s c u s s e d e s t h a t e s of t h e react:i.on r a t e c o n s t a n t k (shown i n Table 3 ) and t h e di.spersion c o e f f i -

c i e n t D (shown i n F i g . 1 3 ) .

Tine r e q u i r e d f l u o r i n a t o r h e i g h t i s show-ii

i n P i g s . 1b-1'r f o r a range o f salt flow r a t e s f o r f o u r fract*ionizl

u r a n i - u r removal v a l u e s ( 0 . 9 , 0.95, 0 . 9 9 , and 0.999).

The uranium con-

c e n t r a t i o n i n t h e i n l e t sa1.t w a s assumed t o be 0.003 mole f r a c t i o n i n

all c a s e s , and t h e f l u o r i n e flow r a t e w a s a s s w e d t o be equal t o

I.. 5 t i m e s t h e s t o i c h i o m e t r i c requirement.

The e f f e c t of f l u o r i n e flow

r a t e i s important s i n c e t h e a x i a l disper.s.ion c o e f f i c i e n t i s dependent on f l u o r i n e flow r a t e .

E x t r a p o l a t i o n of t h e dispersic:m c o e f f i c i e n t

d a t a t o high gas flow r a t e s r e s u l t s i n v e r y h i g h d i s p e r s i o n c o e f f i c i e n t s f o r some o f .the c o n d i t i o n s c o n s i d e r e d . t o b e a conservi%tAve one.) The resu3:t;s

shown

ili

F i g s . 15 and

(This e x t r a p o l a t i o n i s b e l i e v e d

1.6 a r e

encouraging s i n c e they

s u g g e s t t h a t s i n g l e f l u o r i n a t i - o n v e s s e l s of rrioderats s i z e w i l l s u f f i c e for. removing uranium from MSBE fuel s a l t pri.a-f t o t h e i s o l a t i o n of

p r o t a c t i n i u m by rediuc.'iive e x t r a c t i o n .

The r e f e r e n c e flowsheet f o r

i. s o l a t i n g prot a c t i n i u m by f l u o r i n a t i o n - - r ediic t i v e e x t r a c t i o n r e q u i r e s

f l u o r i n a t i o n o f f u e l s a l t a t t h e r a t e o f 170 f t /day, which r e p r e s e n t s

a IO-d-ay p r o c e s s i n g c y c l e .

A 6-in.-diam

f l u o r i n a t o r having a h e i g h t

of 1.0 f t would be r e q u i r e d f o r a uranium removal e f f i c i e n c y of 9 5 % , and a n 8-in.-diam

f l u o r i n a t o r having a h e i g h t o f 1 4 f t would be re-

q u i r e d f o r a uranium removal e f f i c i e n c y o f

99%.

Fluorinators having a hi gh uranium removal e f f i c i e n c y a r e re-

q u i r e d i n t h e p r o d u c t i o n of h i g h - p u r i t y 233U s i n c e incomplete removal

of uranium from a salt stream c o n t a i n i n g "'IJ% would r e s u l t i n contam-

ination of t h e 233U w i t h other iiranium isotopes. F l u o r i n a t i o n of s a l t s t r e a m s having flow r a t e s of 550 t o 1700 f t 3 /day, w i t h uranium removal

e P f i r j e n c i e s as h i g h as 99.9%, may be r e q u i r e d . i f a s i n g l e open-rolwnn continuous f l u o r i n a t o r

A s shown i n F i g . 1'7,

Wei*e

uscd, a coluxn

ORNL- DW G - 70- I471 I - R 2

SALT FLOW RATE, f t / d a y

Fig. 114. Variation of Calculated F l u o r i n a t o r Height w i t h S a l t F1.o~ Rate and Fluorinator Diameter for a Uranium Removal Eff'iciency of 90%.

, T .

Q R N L - D W G - 7Q-8998R2

. T .I O O-C I

lJR AN IU M

R E MOVA L E F FI CI E NCY

INLET URANIUM CONCENTRATION

FLUORINE FEED RATE

95 %

0.003 mole fraction

150 YO of Stoichiometric

IO0

00 SALT R A T E , f t 3 /day

Fig. 15. Variation of Calculated Fluorinator Height, w i t h Salt Flow Rate and Fluorinator Diameter for a Uranium Removal Efficiency of 95%.

ORNL DWG 70-14712R2 IO00 URANIUM REMOVAL EFFiClENCY 99% I N L E T URANIUM CONCENTRATION 0.003 mole fraction FLUORINE FEED RATE 150% of Stoichiometric

100

I--

e, w

5 [r:

3 -I LL

FLUORINATOR DIAMETER

I IO

IO0

IO00

~0,000

S A L T FLOW RATE, ft3/doy

F i g , 16. Variation o f C a l c u l a t e d Fluori.nator Height w i t h Salt Flow Rate and F l u o r i n a t o r Diameter f o r a Uranium Hemoval E f f i c i e n c y o f 99%.

ORNh-BWG- 70-14713R2

INLET URANIUM CONCENTRATlON FLUORINE FEED RATE

0~303mole froction

150 YO of stoichiometric

FLUORINATOR DIAMETER

100 SALT FLOW RATE, fE3//day

F i g . 17. V a r i a t i o n of C a l c u l a t e d F l u o r i n a t o r Height with S a l t FI ow Rate and F l u o r i n a t o r Diameter f o r a Uranimn Removal Efficiency of 99.9%.

39 d i a m e t e r of 10 i n . and h e i g h t s of 36 t o

f t woulci be r e q u i r e d .

t h i s c a s e , the f l u o r i n a t o r would b e diirided i n t o s e v e r a l open-colurnn fluorinators operating i n series.

If two columns were u s e d , t h e re-

q u i r e d column h e i g h t s would be l e s s t h a n h a l f t h e h e i g h t r e q u i r e d for a s i n g l e column s i n c e t h e r e would be rlo a x i a l d i s p e r s i o n a c r o s s t h e

f l u o r i n a t o r i n l e t s and o u t l e t s .

A s shown i n F i g . 18, t h e reyiAir.ed

uranium removal e f f i c i e n c y f o r each colurcui would b e 96.8% and column h e i g h t s of 15 t o 28 f t would b e r e q u i r e d €or a lO-in.-diam

fluorinator.

The u s e of’ t h r e e columns, each of which must have a 90% uranium removal e f f i c i e n c y , would reduce t h e t o t a l columri h e i g h t even f u r t h e r ; h e i g h t s of‘

8 t o 17 f t would be required f o r a lO-in.-diarn

case

fLu.orinat,or i n t h i s

IJSE OF MDI@-F%EQUEHCY I N D U C T I O N HEATING FOR FROZEN-WALL FLUORINATOF DEVEI;OPJ!G.NT STUDIES

J . R. Hightower, J r . C . P. Tung L. E. McNeese

F l u o r i n a t i . o n of molten s a l t f o r removal of uranium i s reg-uirerl at s e v e r a l p o i n t s i n p r o c e s s e s b e i n g c o n s i d e r e d f o r t h e i s o l a t i o n of prot-

actini1.m and for t h e removal of rare earths..

The f l u o r i n a t o r s will be

p r o t e c t e d from c o r r o s i o n by a l a y e r o f s a l t f r o z e n on rnetal s u r f a c e s t h a t w i l l p o t e n t i a l l y c o n t a c t b o t h f l u o r i n e and molten s a l t .

Al-Lhough

t h e s e p a r a t e a s p e c t s o f such operatlions (con-Liiiuous o r b a t c h f l u o r i n a t i o n , and f r o z e n f i l m f o r m a t i o n ) ha-ve been shown e x p e r i m e n t a l l y to be

f e a s i b l e , t h e t e s t i n g of a f l u o r i n a t o r p r o t e c t e d from c o r r o s i o n by a

frozen w a l l h a s been hampered by t h e l a c k of a c o r r o s i o n - r e s i s t a n t

means f o r g e n e r a t i n g h e a t i n t h e molten s a l t .

(The decay of f i s s i o n

p r o d u c t s i n t h e s a l t w i l l c o n s t i t u t e - h e h e a t soilrce i n

r e a c t o r process-

ing plant.) Radio-frequency i n d u c t i o n h e a t i n g a p p e a r s t o be a s u i t a b l e meLlrlod f o r proviciing heat i n e x p e r i m e n t a l work on f l u o r i n a t o r development, and

i t s use i s being studied.

The h e a t would be g e n e r a t e d i n the m o l t m s a l t

WG 76-14714 R 2

r ----

1000L

URANIUM REMOVAL EFFICIENCY 96.838% I N L E T URANIUM CONCENTRATION 0.003 mole f rsction FLUORINE FEED RATE 150% of Stoichiometric

im/

// I

FLUORIM ATOR DI A ME T E W

I I l l 1

I 1 1 1 1

Iom SALT FLOW RATE, ft3/day

IO0

I U

I O,Q06

Fig. 18. Variation of Calculated Fluorinator Ileighi wiih Salt Flow Fluorinator D i a m e t e r foi- a Uranium Netntlval Efficiency of 96.838%,

H a t e and

(a conductor) by eddy currents induced by an alternating magnetic field.

The magnetic field would be generated by a coil not in contact with the

molten salt.

This method of generating heat in the salt has the disad-

vantage that heat would also be produced in the metal walls of the fluorinator, although this c a n be minimized by choosing a favorable geometry.

Two promising coil Configurations (see Fig, 19) w i l l . be considered

in the remainder of this section, In the first configuration (config-

uration I), ?,he induction coil is located just inside the metal wall

of the cylindrical fluorinator vessel and is embedded in a frozen salt film

011

the vessel wall.

Heat is generated inside the coil by the

magnetic field, and neither the coil nor the vessel wall would be in contact with molten salt and fluoride. In the second configuration

(configuration 111, the induction coil would be much smaller in diameter

than the fluorinator vessel and would be located at the center of the

fluorinator, A coolant; would be passed through the induction coil in

order to cover it with a layer of frozen saltn Heat would be generated

in the molten salt (and in the vessel wall) by the magnetic field outside

the coil. The second configuration requires

greater total heat genera-

tion rate than the first configuration since a larger area would be covered with frozen salt

5.1 Mathematical Analysis Initial work on the problem was directed toward a mathematical

analysis of several coil configurations in order to assess the feasi-

bility of rf heating and to identify important system parameters. Sev-

eral configurations, includigg the two shown in Figo 19, were examined.

These include a configuration in which the induction coil was locased

outside the fluorinator vessel wall, which would be relatively thin to

permit power to be transmitted through it. Since it appeared that most of the heat generation for systems having dimensions of interest would

occur in the metal w a l l , t h i s configuration was not consid-ered further,

Configuration I (see Fig. 19) is more amenable to mathematical analysis

than configuration 11, and expressions are available fyom standard texts

on induction heating

22,23

for predicting coil performance.

MOLTEN SALT

m k 0

ri cd

43 C a l c u l a t i o n s were made for p r e d i c t i n g t h e performance o f two systems: (1) a s a l t system having t h e approximate dimensions of an ex-

p e r i m e n t a l frozen-wall f l u o r i n a t o r t h a t w i l l b e b u i l t l a t e r , and (2)

a system u s i n g s u l f u r i c a c i d (which has p r o p e r t i e s similar

t o molten s a l t ) .

Rate of Heat Generation i n Molten S a l t . - T h e

r a t e of h e a t genera-

t i o n i n t h e m o l t e n - s a l t r e g i o n o f a frozen-wall f l u o r i n a t o r w a s approxi-

mated by a n e q u a t i o n f o r t h e r a t e o f h e a t g e n e r a t i o n i n a n i n f i n i t e l y long c y l i n d r i c a l charge i n s i d e an i n f i n i t e l y long c o i l . 24 t i o n rate p e r u n i t l e n g t h of charge i s :

The h e a t genera-

where P = power g e n e r a t e d i n c h a r g e , W/cm, p = p e r m e a b i l i t y of c h a r g e ,

f = frequency, Hz,

rl = r e s i s t i v i t y of t h e c h a r g e , SI-em,

n = c o i l spacing, turns/cm,

a = r a d i u s of c h a r g e , cm, i = r m s c o i l c u r r e n t , A.

The f a c t o r F i n E q . ( 6 ) i s d e f i n e d by t h e f o l l o w i n g e q u a t i o n :

F = b e r ( A ) b e r l ( A ) C b e i ( A )2b e i ' ( A ) , (ber(A))' + (bei(A))

where A i s d e f i n e d as a G h 5 5 8 Bessel functions.

6 and b e r ,

ber'

, bei,

and b e ? ' are

44 Heat Generation Rate i n F l u o r i n a t o r Wall. - N o equations for c a l -

c u l a t i n g t h e heat generation rate in a c y l j n d r i c a l shell. surrounding

a cylindrical coil were found in the literature.

Therefore, we estimated

t h e heat g e n e r a t i o n r a t e in t h e fluorinstor wall by assuming that the heat

g e n e r a t i o n r a t e i n t h e pipe j u s t o u t s i d e the c o i l was t h e % m e as that in

a p i p e just i n s i d e a coil; the i n t e n s i t y o f the magnetic f i e l d w a s assumed

t o be t h e s a c at t h e surface a d j a c e n t t o t h e coil. i n each case,

For the

high frequencies we expect to use ( P >300 ~ H z ) , t h e penelration depths are

very small and RS

metal p i p e would be For this case,

a solid cylinder.

value of e / 2 , and t h e e q u a t i o n that e r a t i o n i n the pipe is as follows:

where p

17 =: heat, geIlerated in pipe, W/cm, P

= perneahili-ty of p i p e ,

= r e s i s t i v i t y of pipe, R-em,

P H = inside r a d i u s of pipe, cn. P Equation ( 8 ) will be used o n l y to o b t a i n a rough estimate of the h e a t

g e n e r a t i o n rate i n the pipe; the actual heat g e n e r a t i o n rate w i l l be

measured experimentally

R e s i s t a n c e Losses in t h e Induction C a . - T h e

.i.nduction c o i l i s given by the following equation:25 R C

= 63.2kr

( f n c ) 1/2 dcn2

resistance of the

x 19-8

whC2-e

Rc = resistance of t h e coil, s1 per cm of axial length,

kr = c o r r e l a t i o n f a c t o r (assumed t o he 1 . 5 ) , f = frequency, Hz,

(9)

45 rlc

= r e s i s t i v i t y of t h e c o i l , VQ-cm,

= diameter of t h e c o i l , i n . ,

n = c o i l spacing, turns/in. The r e s i s t i v e l o s s e s i n t h e c o i l are g i v e n , t h e n , by: 2 . PC = i RC ( i n w/cm>.

Conduction o f Heat Through a Film of Frozen S a l t . - I t was assumed

t h a t a l l h e a t g e n e r a t e d i n t h e molten s a l t i n t h e c e n t e r o f t h e f l u o r i n a t o r i s t r a n s f e r r e d by conduction through t h e film of f r o z e n s a l t on t h e f l u o r i n a t o r w a l l , which i s m a i n t a i n e d a t a t e m p e r a t u r e below t h e l i q u i d u s temperature of t h e salt.

The e q u a t i o n r e l a t i n g t h e h e a t

t r a n s f e r r e d through t h e frozen film t o t h e temperature d i f f e r e n c e , t h e dimensions o f t h e f i l m , and t h e p r o p e r t i e s of t h e f r o z e n f i l m i s : 2nks ( T i

P =

Tc)

In (R/a)

â&#x20AC;&#x2122;

where P = r a t e a t which h e a t i s t r a n s f e r r e d t h r o u g h t h e f r o z e n f i l m , k

= t h e r m a l c o n d u c t i v i t y of t h e f r o z e n f i l m ,

a = r a d i u s of t h e molten s a l t - - f r o z e n

R = a

+ t,

salt interface,

where t i s t h e t h i c k n e s s of t h e f r o z e n s a l t ( R i s assumed

t o be t h e i n s i d e r a d i u s o f t h e c o i l ) ,

Ti = t h e t e m p e r a t u r e of the s o l i d - l i q u i d i n t e r f a c e , i.e., l i q u i d u s t e m p e r a t u r e of t h e s a l t ,

Tc = t e m p e r a t u r e i n t h e f r o z e n f i l m a t t h e o u t s i d e of t h e c o i l .

46 C a l c u l a t e d ResulLs for a Molten-Salt F l u o r i n a t o r

5.2

The f l u o r i n a t o r system t h a t was examined. had t h e f o l l o w i n g f e a t u r e s :

The s a l t w a s LiF-BeF -'ThE'h (68-20-12 mole % ) ; t h e i n s i d e d i a m e t e r of t h e 2 1 / 4 - i n . - t h i c k vessel w a s 4.9 i n . ; t h e mean diameter o f the i n d u c t i o n c o i l

w a s 3.9 i n . ; t h e f r o z e n s a l t extendkd i n from t h e wall, covei-in@;t h e coil-.

molten c(3i-e; and t h e t e m p e r a t u r e d i f f e r e n c e

and l e a v i n g a l . g - i n . - d i a m

a c r o s s t h e f r o z e n s a l t laye?- was l.OO째C. same e l e c t r i c a l p r o p e r t i e s as Monel..

The m e t a l was assumed t o have .the

The heat g e n e r a t i o n raLe i n the m.01-

t e n sa1.t n e c e s s a r y t o matntair; t b , i s f r o z e n s a l t l a y e r w a s 63 meter of f l u o r i n a t , o r l e n g t h .

per e e n t i -

The calciilated induction current i n t h e coil.

( a t a n assuiiied frequency of 500 kHz) n e c e s s a r y t o produce t h i s h e a t get-I-

e r a t i o n r a t e i n t h e s a l t was 24.7 A .

Using t h e assumption g i v e n p r e v i o u s l y ,

6'7W/cm

t h e c a l c u l a t e d g e n e r a t i o n r a t e i n the f l u o r i n & t o r v e s s e l w a l l w a s ( a b o u t 1.05 t i m e s t h e heat generated i n t h e salt).

Removal. of t h i s 8.r1111im.t

o f h e a t g e n e r a t e d i n t h e vessel w a l l , as w e l l as t h a t generabed i n t h e

Fo;. a 5-ft-long f l u o r i n a t o r v e s s e l , t h e s e c a l -

s a l t , would be p r a c t i c a l .

c u l a t i o n s i n d i c a t e t h a t a 28-kW rf g e n e r a t o r would be r e q u i r e d .

Similar

c a l c u l a t i o n s cou1.d not be m d e c o n v e n i e n t l y f o r c o n f i g x a t i a n 11

5.3

Experimentally Xeas-.ired Heat Generati-on Rates

I n o r d e r t o v e r i f y t h e vaiues predicted for c o n f i g u r a t i o n 1 and t o

e v a l u a t e t h e pel-formtznee o f c o n f i g u r a t i . o n 11, i n which a 29 w t

T C T ~

c a r r i e d o u t experiments

% U2SOh sol.iitLor w a s s u b s t i t u t e d for molten s a l t .

iieat

g e n e r a t i o n F a t e s were measured i.n t h e a c i d and i n a Monel p i p e surrounding the acid.

T h e acj-d w a s c o n t a i n e d i n a 2 - l i t e r g.rad.uated c y l i n d e r

havi.ng an t n s i d e diameter of

of 6-in.

sched 40 Monel.

3-1/4 i z .

The pipe was a 6-in.-l.ong

section

The c o i l f o r t h e t e s t w i t h c o n f i g u r a t i o n I was

i n . i n i n s i d e d i a m e t e r by 6 i n . l c n g and c o n s i s t e d o f 20 tui-ns o f 1./4-

in.-diam. copper t u b i n g ; it w a s p l a c e d around t h e a c i d container, and t h e

6-in. l-l./h

p i p e was p l a c e d around t h e coil. i n . i n outside diameter by

l/b-in.-dim

copper t u b i n g .

The coi.1 fox- c o n f i g u r a t i o n I1 was

6 i n . long

and c o n s i s t e d of 20 t u r n s of

It w a s p l a c e d i n a 1 - 3 / 8 - i n . - o ~ glass t u b e ,

47 which w a s immersed i n t h e c e n t e r of t h e a c i d ,

The h e a t g e n e r a t i o n r a t e s

were o b t a i n e d by measuring t h e r a t e s o f t e m p e r a t u r e i n c r e a s e i n t h e a c i d and i n t h e p i p e .

In t h r e e r u n s w i t h c o n f i g u r a t i o n I , -the r a t i o of h e a t g e n e r a t e d i n

t h e p i p e t o t h a t g e n e r a t e d i n t h e a c i d averaged 1.3.

The frequency i n

t h e t e s t w a s 350 kIlz, and t h e c o n d u c t i v i t y of t h e a c i d was about 0.75 mho/cm,

The h e a t g e n e r a t i o n r a t e i.n t h e a c i d w a s about

1-9W

per centi-

meter o f c o i l l e n g t h ; t h i s w a s k e p t low t o p r e v e n t t h e a c i d from b o i l i n g . The p r e d i c t e d v a l u e f o r t h e r a t i o of heat g e n e r a t e d i n t h e p i p e t o t h a t g e n e r a t e d i n t h e a c i d w a s 0.58 ( t h i s v a l u e w a s c a l c u l a t e d by u s i n g t h e p r o p e r t i e s , c o n d i t i o n s , and dimensions of t h e e x p e r i m e n t a l system, and by making t h e assumptions t h a t w e r e o u t l i n e d i n t h e p r e v i o u s s e c t i o n ) , which i s approximately one-half t h e measured value.

Deviations i n h e a t

g e n e r a t i o n r a t e of t h i s magnitude between t h e p r e d i c t e d and measured v a l u e s a r e not s u r p r i s i n g s i n c e t h e met'nod used f o r c a l c u l a t i n g h e a t g e n e r a t i o n i n t h e p i p e w a s an approximate one. I n f i v e r u n s w i t h c o n f i g u r a t i o n 11, t h e r a t i o of h e a t g e n e r a t e d i n

t h e p i p e t o t h a t g e n e r a t e d i n t h e a c i d had an average v a l u e of 0.069.

The

f r e q u e n c y i n t h i s t e s t was 440 kHz. The h e a t g e n e r a t i o n r a t e i n t h e a c i d ,

u s i n g c o n f i g u r a t i o n 11, w a s about 16 W p e r c e n t i m e t e r of c o i l l e n g t h , even though a h i g h e r p l a t e xsoltage w a s used t h a n i n t h e experiments w i t h con-

figuration I.

T h i s i n d i c a t e s t h a t t h e c o u p l i n g of t h e magnetic f i e l d

w i t h t h e a c i d was p o o r e r w i t h c o n f i g u r a t i o n I1 t h a n w i t h c o n f i g u r a t i o n I ;

such a r e s u l t i s t o be expected s i n c e t h e magnetic f i e l d s t r e n g t h o u t s i d e

a c o i l i s smaller t h a n t h e s t r e n g t h i n s i d e a c o i l .

However, it means

t h a t , even though o n l y a s m a l l m o u n t of h e a t w a s g e n e r a t e d i n t h e p i p e

w a l l w i t h c o n f i g u r a t i o n 11, t h e e f f i c i e n c y o f h e a t i n g t h e s a l t c o u l d s t i l l b e much l e s s t h a n i f c o n f i g u r a t i o n I were used, because t h e h e a t g e n e r a t i o n i n t h e c o i l i t s e l f might be l a r g e compared w i t h t h e h e a t generation i n t h e salt.

T h i s a s p e c t w i l l be e x p l o r e d i n f u t u r e e x p e r i -

ments when means t o measure t h e c o i l c u r r e n t have been o b t a i n e d ,

i n general, r e s u l - t s o f 'these prel.iminary experiments and calcula-

t i o n s encourage u s t o b e l i e v e t h a t i n d u c t i v e heai;ri.ng i s a r e a s o n a b l e

method f o r supplying h e a t t o an experiment designed t o s t u d y a f l u o r i n a t o r c o n t a i n i n g a f r o z e n w a l l b u t no i n t e r n a l h e a t g e n e r a t i o n resulti n g from f5ssi.on product decay.

Disagreenent bet,ween the measured and

t h e c a l c u l a t e d v a l u e s of r e l a t i v e heat g e n e r a t i o n rates i n d i c a t e s t h a t t h e d e s i g n of an experimental f l u o r i n a t c : e m p i r i c a l l y o b t L n e 6 rei.azi onships.

this i n f o r m a t i o n i s imde-r imy.

system!must r e l y h e a v i l y on

An e x p e r i m e n t a l program t o o b t a i n

MSRE DIST lLLA4T GN EDERIMENT

J. R. Hightower, Jr.

L. E . McNeese

EP feeti v e i - e l a t i v e

ancl of t h e f l u o r i d e s of - --lJ'(Cs have been c a l c u l a t e d from condensate a n a l y s e s made d u r i n g t h e MSXE

D i s t i l l a t i o n Experiment. viously,

These r e s u l t s , which have been d i s c u s s e d pre-

show that a l l of t h e component!; excep1; BeF

2 and ZrF 4 had ef-

f e c t i v e P e l a t i v e v o l a t i l j . t i e s t h a t d e v i a t e d ( d r a s t i c a l l y i n some c a s e s )

from v a l u e s p r e d i c t e d from t e s t s wi.tl: e q u i l i b r i w . systems causes f o r t h e discrepancies include: still-pot

Possible

(1)entrainment of d r o p l e t s o f

I.iqi.ij-d i n t h e v a p o r , ( 2 ) c o n c e n t r a t i o n g r a d i e n t s i n the sti1.l.

p o t , and ( 3 ) contamination o f samples d u r i n g t h e i r p r e p a r a t i o n f o r r a d i o chemic a1 aiialy s j- s

Entrainment w a s s u s p e c t e d f o r a number o f r e a s o n s .

F a r example,

entrainment of o n l y 0.023 mole o f l i q u i d p e r mole of vapor would account f o r t h e h i g h r e l a t i v e v o l a t i l i t i e s cal.culated f o r t h e s l i g h t l y v o l a t i l e S)dbCe 14'7 f is s i o n p r o d u c t s , I'm, 'lY, and 'OS,. Entrainment r a t e s of

t h i s o r d e r would not be r e f l e c t e d i n t h e e f f e c t i v e r e l a t i v e v o l a t i l i t i e s

o f more v o l a t i l e m a t e r i a l s ( a

1 ) . The high c o r r e l a t i o n of t h e s c a t t e r

of t h e cal.culat;ed e f f e c t i v e r e l a t i v e v o l a t i l i t i e s o f d i f f e r e n t s l i g h t l y v o l a t i l e f i s s i o n p r o d u c t s i s c o n s i s t e n t wi.th t h e h y p o t h e s i s t h a t entrainment occurred.

49 S i n c e e n t r a i n m e n t was n o t a p p a r e n t i n t h e n o n r a d i o a c t i v e o p e r a t i o n

of t h e s t i l l , 2 7 r e a s o n s f o r e n t r a i n m e n t i n t h e r a d i o a c t i v e o p e r a t i o n were sought t o s u p p o r t t h e h y p o t h e s i s ,

Evidence of a s a l t m i s t above t h e s a l t

i n t h e pimp bowl a t t h e MSRE and above s a l t samples removed from t h e PSRE h a s been r e p o r t e d . 28329

F u r t h e r , s t u d i e s have i n d i c a t e d t h a t t h e s e m i s t s

are p r e s e n t o v e r r a d i o a c t i v e s a l t m i x t u r e s b u t n o t over n o n r a d i o a c t i v e m i x t u r e s ; however, examination o f d a t a from t h e s e s t u d i e s showed t h a t e n t r a i n m e n t r a t e s l a r g e enough t o e x p l a i n t h e r e s u l t s of t h e MSRE Dis-

% i l l a t i o n Experiment c o u l d be o b t a i n e d o n l y by assuming t h a t t h e con-

c e n t r a t i o n of s a l t i n t h e g a s space above t h e s a l t d u r i n g t h i s e x p e r i ment w a s equal t o t h a t observed above s a l t i n t h e pump bowl a t t h e MSHE. If t h e r a t e a t which t h e m i s t i s formed d e c r e a s e s as t h e power d e n s i t y

i n t h e l i q u i d d e c r e a s e s , t h e c o n c e n t r a t i o n of s a l t i n t h e m i s t should a l s o d e c r e a s e as t h e power d e n s i t y i n t h e l i q u i d d e c r e a s e s .

Since t h e

s a l t used i n t h e MSRE D i s t i l l a t i o n Experiment had a much lower power d e n s i t y (400-day decay p e r i o d f o r d i s t i l l a t i o n f e e d as compared w i t h l e s s than 30 day decay p e r i o d f o r s a l t samples t e s t e d f o r m i s t f o r m a t i o n ) t h a n s a l t samples from t h e MSRE, it seems u n l i k e l y t h a t t h e concentra-

t i o n of s a l t i n t h e gas above t h e s a l t would have been h i g h enough t o

explain t h e high r e l a t i v e v o l a t i l i t i e s f o r t h e s l i g h t l y v o l a t i l e f i s s i o n products.

I n a d d i t i o n t o t h e argument a g a i n s t t h e entrainment h y p o t h e s i s

g i v e n above, n o t a l l d i s c r e p a n c i e s would b e e x p l a i n e d by i t .

For example,

it would not account f o r t h e v a r i a t i o n s i n t h e 89Sr/90Sr a c t i v i t y r a t i o and f o r t h e low v a l u e f o r t h e e f f e c t i v e v o l a t i l i t y of 137Cs. C o n c e n t r a t i o n p o l a r i z a t i o n would cause t h e e f f e c t i v e r e l a t i v e v o l -

a t i l i t i e s of t h e s l i g h t l y v o l a t i l e m a t e r i a l s t o be g r e a t e r t h a n t h e t r u e r e l a t i v e v o l a t i l i t i e s G A s t h e m o r e - v o l a t i l e materials v a p o r i z e d from t h e s u r f a c e of t h e l i q u i d , t h e s l i g h t l y v o l a t i l e materials would be l e f t behind on t h e s u r f a c e a t a h i g h e r C o n c e n t r a t i o n t h a n i n t h e l i q u i d J u s t below t h e s u r f a c e .

The c o n c e n t r a t i o n of t h e s e s l i g h t l y v o l a t i l e materials

i n t h e vapor would t h e n i n c r e a s e s i n c e f u r t h e r v a p o r i z a t i o n would occur

from a l i q u i d w i t h a h i g h e r s u r f a c e c o n c e n t r a t i o n of s l i g h t l y v o l a t i l e materials.

S i n c e e f f e c t i v e r e l a t i v e v o l a t i l i t i e s w e r e based on average

c o n c e n t r a t i o n s i n t h e s t i l l p o t , t h e c o n c e n t r a t i o n i n t h e vapor would be h i g h e r t h a n t h a t corresponding t o t h e average concentrat,i.on i n t h e 1.iquid; a l s o , t h e c a l c u l a t e d effecti-lre v o l a t i l i t y - %~oid.,dbe h i g h e r ihaa t h e t r u e relative volatility.

C o n c e n t r a t i o n p o l a y i z a t i o n would cause t h e e f f e c t i v e

r e l a t i v e v o l a t i l i t y t o be lower t h a n t h e a c t u a l r e l a t i v e v o l a t i l i t y i n t h e case o f a component whose r e l a t i v e v o l a L i l i t y i s g r e a t e r t h a n 1. The e x t e n t t o which c o n c e n t r a t i o n p o l a r i z a t i o n affects t h e e f f e c t i v e

rei-ative v o l a t i l i t y o f a p a r t i c u l a r component depends on t h e d i m e n s i o n l e s s

group D/vL, which q u a J . i t a t i v e l y r e p r e s e n t s the r a t i o of t h e rate of d i f -

f u s i o n o f a p a r t i c u l - a r component from t h e v a p o r - l i q u i d i n t e r f a c e i n t o the

bulk of t h e s t i l l . - p o t l i q u i d t o t h e r a t e a t which t h i s m a t e r i a l i s t r a n s f e r r e d by c o n v e c t i o n t o t h e i n t e r f a c e by l i q u i d rjnoving toward t h e vaporization surface.

In t h i s r a t i o , D i s t h e e f f e c t i v e d i f f u s i v i t y of t h e

component of i n t e r e s t , v i s t h e v e l o c i t y of l i q u i d moving toward t h e i n t e r f a c e , and L i.s t h e d i s t a n c e between t h e i n t e r f a c e and t h e p o i n t

where t h e f e e d i s i n t r o d u c e d .

'The o c c u r r e n c e of c o n c e n t r a t i o n p o l a r i z a L i o n i s suggested by t h e

s h a r p i n c r e a s e : a t t h e beginning o f t h e ruin. i n t h e effect.i.ve r e l a t i v e v o l a t i l i t i e s of 144ce,

147,

l"Eu,

and, p o s s i b l y , of 9lY and

'Os,.

'Phis i n c r e a s e would correspond t o t h e f o r m a t i o n o f a c o n c e n t r a t i o n gra.di.ent i n t h e s t i l l - p o t l i q u i d .

'The e f f e c t i v e d i f f u s i v i t i c s o f NdF

i n the s k i l l p o t , c a l c u l a t e d from r e s u l t s of t h e n o n r a d i o a c t i v e e x p e r i -

-4

m e n t s , ranged from 1 . 4 x 19

-4 cm2/sec

t o 16 x 1 0

and form .the b a s i s

for. e s t i m a t i n g t h e magnitude of tile c o n c e n t r a t i o n p o l a r i z a t i o n e f f e c t

i n the radioactive operation.

h i - i n g t h e semiconticuous o p e r a t i o n a t

t h e MSIYE, t h e l i q u i d v e l o c i t y r e s u l t i n g from v a p o r i z a t i o n averaged 2.2

-4

x 10

cm/sec; t h e depth of l i q u i d above t h e i n l e t w a s about

9.4 cm.

I F o n e assumes t h a t t h e e f f e c t i v e d i f f u s i v i t i e s o f t h e f i s s i o n p r o d u c t s

i n the s t i l l p o t d u r i n g t h e MSRE D i s t i l l a t i o n Experiment were i n the

same range as t h e y were d u r i n g t h e nonradi.oac.tive t e s t s , the observed

relat,j.ve v o l a t i l i t i e s af t h e s l i g h t l y v o l a t i l e materials would be on1.y 2 . 0 t o 18 times t h e t r u e r e l a t i v e v o l a t i l i t y and t h e observed r e l a t i v e

v o l a t i l i t y of 137Cs would be 0 . 0 1 1 t o 0.021 times i t s t r u e v a l u e (as-

suming, i n each c a s e , t h a t Lhe t r u e r e l a t i v e v o l a t i l i t i e s a r e t h o s e g i v e n i n r e f s . 27 and 2 8 ) .

Although c o n c e n t r a t i o n p o l a r i z a t i o n nay have been

s i g n i f i c a n t i n t h e work w i t h r a d i o a c t i v e s a l t , t h e e f f e c t w a s not g r e a t enough t o account; f o r t h e d i s c r e p a n c i e s between t h e observed r e l a t i v e vol-

a t i l i t i e s and what we c o n s i d e r t o be t h e t r u e v a l u e s .

Also c o n c e n t r a t i o n

p o l a r i z a t i o n would n o t e x p l a i n t h e v a r f a t i o n i n t h e 89Sr

activity

r a t i o between samples of condensate. The p o s s i b i l f t y thaf;t h e condensate samples became contaminated

w h i l e t h e y were b e i n g p r e p a r e d f o r r a d i o a c t i v e a n a l y s i s i s s u g g e s t e d by t h e wide v a r i a t i o n i n t h e v a l u e of t h e 0gSrf90Sr a c t i v i t y r a t i o .

Al-

though r o u t i n e p r e c a u t i o n s a g a i n s t contamination were t a k e n i n t h e hot c e l l s , where t h e c a p s u l e s were c u t open, no s p e c i a l procedures were

used and t h e m a n i p u l a t o r s used t o handle MSRE s a l t samples were a l s o used t o open t h e condensate samples.

I f it i s assumed t h a t t h e s o u r c e

of t h e c o n t a m i n a t i o n was t h e l a s t s a l t sample t a k e n from t h e MSRE b e f o r e

-6 t o

t h e d i s t i l l a t i o n samples were s u b m i t t e d , o n l y 1 0

g of s a l t p e r

gram of sample would be r e q u i r e d t o y i e l d t h e observed v a l u e s of t h e

89Sr and 90Sr a c t i v i t i e s .

Contamination from such small q u a n t i t i e s of

m a t e r i a l would be extremely d i f f i c u l t t o p r e v e n t

Gther o b s e r v a t i o n s e x p l a i n e d by a s s m i n g t h a t t h e samples were cont a m i n a t e d are t h e h i g h r e l a t i v e v o l a t i l i t i e s of t h e s l i g h t l y v o l a t i l e f i s s i o n p r o d u c t s and t h e c l o s e c o r r e l a t i o n between t h e v a r i a t i o n s of c a l c u l a t e d r e l a t i v e v o l a t i l i t i e s of d i f f e r e n t f i s s i o n p r o d u c t s . t h e low r e l a t i v e v o l a t i l i t y PoY" 137Cs

However,

i s riot e x p l a i n e d by t h i s h j p o t h e s i s .

We conclude t h a t , a l t h o u g h s e v e r a l f a c t o r s may be i n v o l v e d , t h e d i s -

crepancy between t h e e f f e c t i v e r e l a t i v e v o l a t i l i t i e s of t h e s l i g h t l y vol-

a t i l e materials measured i n t h i s experiment and t h e v a l u e s measured prev i o u s l y i s p r i m a r i l y t h e r e s u l t of contamination o f t h e condensate samples

by minute q u a n t i t i e s of o t h e r MSRE s a l t samples i n t h e h o t c e l l s ,

'T.

DEVELOPMENT OF THE METAL TRANSFER PROCESS E. L. Youngblood W e F. S c h a f f e r , Jr. L. E. McNeese E. 1;. Nicholsor: J . R. Hightower, J r .

Rare e a r t h s have been found t o d i s t r i b u t e s e l e c t i v e b j i n t o molten J , i C I from bismui;h s o h t i o n s c o n t a i n i n g rare e a r t h s and thorium, and an

improved r a r e - e a r t h removal p r o c e s s based on t h i s o b s e r v a t i o n has been Work t h a t w i l l demonstrate all. phases o f t h e improved p r o c e s s ,

devised.

kriown as t h e metal t r a n s f e r p r o c e s s , i s under way.

'7.1

Equipment and Experimental P r a e e d x e

EquipLent h a s been f a b r l c a t e d f o r s t u d y and demonstration o f t h e m e t a l t r a n s f e - r p r o c e s s f o r s e l e c t i v e l y removing r a r e e a r t h s from singlef l u i d MSBR fuel s a l t .

The f i r s t s e r i e s of experiments

Till

be c a r r i e d

o u t i n a 6-in.-diam compartmented v e s s e l ( F i g . 2 0 ) f a h r i c a t e d from carbon

st,eel.

The v e s s e l i s 24 i n . high; and t h e i n t e r n a l p a r t i t i o n , which

d i v i d e s t h e v e s s e l i a t o two e q ~ a l - - v o l u m ecompartments

t e r m i n a t e s 1/ 2 i n .

above the bottom o f t h e v e s s e l . During each e x p e r h e n t , t3e \*esse1 w i l l c o n t a i n a 2-in.

muth ( i . e . ,

depth o f bis-

0.8 l i t e r ) t h a t i s s a t u r a t e d w i t h thori1-m a t t h e o p e r a t i n g

t e m p e r a t u r e o f 640째C and two s a l t phases having d e p t h s o f 3 t o 11. i n . ( 0 . 7

t o 1.0 l i t e r each). 1 2 mole

One sa.1.t phase w i l l b e MSBR f u e l c a r r i e r s a l t (72-16-

% LiF-BeF -ThF ) i n i t i a l l y conta,ining 0.3 mole % LaF and about 5

m C i of 14''NdF

t h e o t h e r s a l t phase w i l l b e L i C 1 .

The L i e 1 compartment

a l s o c o n t a i n s an e l e c t r i c a l l y i n s u l a t e d cup c o n t a i n i n g a L i - B i and a punip f o r c i r c u l a t i n g LiCl through t h e cup. about 200 cn? o f B i - L i

mole f r a c t i o n .

solution

The cup w i l l c o n t a i n

s o l u t i o n having a l i t h i u m c o n c e n t r a t i o n of 0.40

P r o v i s i o n i s made f o r a g i t a t i n g t h e l i q u i d phases and

f o r sampling all phases.

During o p e r a t i o n , L a and Nd w i l l b e t r a n s f e r r e d

f r o m t h e fue1. s a l t t o t h e LiCI. by c i r c u l a t i o n o f t h e Th-Bi s o l u t i o n t h a t w i l l also contain t h e r a r e earths.

F r a c t i o n s of t h e L a , Nd, and Th w i l l

then b e e x t i - a c t e d from t h e L i C l by c o n t a c t i n g the LiCI. w i t h t h e Li-Ri solution.

ORNL- D W G - 7 0 - 4 5 0 4 R I -LEVEL

CONTROLLER

LEVEL ELECTRODES

ARGON

VENT

CA R80N- ST EE L

.-QUARTZ PUMP

6-in. CARBONSTEEL PIPE 24 in.

72-16-12 MOLE Yo FUEL CARRIER SALT

Fig. 2 0 .

TLiCl -,Li

- 8i

Carbon-Steel Vessel fox. IJse in the Metal T r a n s f e r Experiment.

54 To b e g i n an experiment, t h e t h r e e phases i n c o n t a c t ( f u e l salt,

bismuth, and L i C 1 ) w i l l b e allowed t o approach e q u i l i b r i u m and samples of t h e phases w i l l be t a k e n .

The L i C l w i l l t h e n be pumped t h r o u g h t h e

r e s e r v o i r c o n t a i n i n g t h e L i - B i s o l u t i o n a t a flow r a t e of about; 25 cm3/

min i n o r d e r t o remove t h e r a y e e a r t h s and thorium from t h e L i C 1 . L i C l w i l l overflow t h e L i - B i

volime.

The

r e s e r v o i r and r e t u r n t o t h e i n i t i a l . L i C l

After a F e r i o d o f about 3 hr, c i r c u l a t i o n o f t h e L i C l w i l l be

stopped and Lhe system w i l l be allowed to approach e q u i l i b r i u m .

of t h e phases w i l l t h e n b e taken.

Samples

It i s e s t i m a t e d t h a t 5 t o 1.0% of t h e

lanthanum i n i t i a l l y p r e s e n t i n t h e f u e l s a l t w i l l have been t r a n s f e r r e d solution at t h i s point.

t o the Li-Bi

The above sequence of o p e r a t i o n s

w i l l t h e n b e repeated. u n t i l . t h e desi.red f r a c t i o n of t h e lanthanum has

been t r a n s f e r r e d t o t h e L i - B i w i l l be used t o g i v e

s o l u t i o n ( 5 0 t o go%),

The 14?Nd t r a c e r

r a p i d i n d i c a t i o n of t h e rate a t which t h e r a r e

e a r t h s a r e t r a n s f e r r e d d u r i n g t h e experiment. '7.2

Developinent and T e s t i n g of a Punip f o r C i r c u l a t i n g Lie1

Several. pumps f o r c i r e u l a - t i n g t h e L i C l have been f a b r i c a t e d and t e s t e d f o r u s e i n t h e experiment.

'The f i r s t p u i p , made from 1-1/2-1n.-

dim q u a r t z t u b i n g , was t e s t e d i n a b-in.-diajn

i n F i g . 21.

q u a r t z v e s s e l , as shown

The punp w a s d r i v e n by v a r y i n g t h e d i f f e r e n c e i n argou

pressure between t h e i n s i d e and til? o u t s i d e of t h e pump chamber.

The

d i r e c t i o n of f l o w w a s determined by weighted q u q r t z check v a l v e s on t h e pump i n l e t and o u t l e t .

I n o p e r a t i o n , the f l o w of argon was controll-ed by so1enoi.d v a l v e s

t h a t were a c t u a t e d by s i g n a l s from two l e v e l probes i n 'ihe p~unpt u b e .

During the f i r s t p a r t of a pump c y c l e , t h e v e s s e l w a s p r e s s u r i z e d w i t h argc)n, which Yorced l i q u i d i n t o t h e pump chamber through t h e pump i n l e t u n t i l t h e l i q u i d c o n t a c t e d t h e h i g h - l e v e l probe ( F i g . 2 1 ) .

When c o n t a c t

w i t h t h e h i g h - l e v e l probe w a s made, t h e s o l e n o i d v a l v e s ac-busted t o v e n t t h e t e s t v e s s e l and p r e s s u r i z e t h e pimp chamber; t h i s f o r c e d I.i.qpid o u t through t h e pump o u t l e t .

When t h e l e v e l o f t h e l i q u i d i n t h e pump chamber

dropped below t h e low-level probe, t h e s o l e n o i d Val-ves were a g a i n a c t u a t e d

and t h e cyc1.e

was r e p e a t e d .

55 ORNL PHOTO 98323

CONDENSER FOR LiCl VAPOR

4-1 N, -D LAM QUARTZ TEST VESSEL

HIGH-LEVEL PROBE

1-1/2-IN.-OP QUARTZ PUMP TUBE

PUMP OUTLET

MAGNESIA SUPPORT

4’ PROBE

. r

GROUND

LOW-LEVEL PROBE

QUARTZ CHECK VALVES

Fig. 21. Pump f o r Circulating L i C 1 , I n s t a l l e d in b-in.-diam T e s t Vessel.

Quartz

56 F i g u r e 21shows t h e pump i n o p e r a t i o n w i t h a c o l o r e d aqueous s o l u t i o n of L i C 1 .

During t e s t s w i t h t h i s m i x t u r e , we observed t h a t t h e q u a r t z check

v a l v e s had a tendency t o s t i c k .

Before t e s t i n g t h e pump w i t h molten L i C 1 ,

we added s u p p o r t s to t h e weighted q u a r t z check v a l v e s (which were t e a r d r o p shaped) t o p r e v e n t them from t i p p i n g over.

This m o d i f i c a t i o n w a s not

e n t i r e l y s u c c e s s f u l ; t h e v a l v e s continued t o s t i c k , although not as frequently. A f t e r m o d i f i c a t i o n , t h e q u a r t z pump w a s t e s t e d w i t h molten L i C 1 . h-in.-diam

The

q u a r t z v e s s e l c o n t a i n i n g t h e pump w a s loaded w i t h 800 g o f L i C l

t h a t had n o t been p r e v i o u s l y d r i e d , and t h e system w a s h e a t e d t o o r d e r t o melt t h e L i C l and remove water from t h e s a l t .

650'~

The pump and t h e During

g a s space of t h e v e s s e l were purged w i t h argon during t h i s p e r i o d .

t h e heatup p e r i o d , t h e presence of a l i q u i d having a pH of about 2 was observed on t h e v e s s e l w a l l s .

When t h e pump w a s lowered i n t o o p e r a t i n g

p o s i t i o n , we found t h a t t h e l e v e l probes had s h o r t e d ; t h i s s h o r t i n g w a s probably caused by an accumulation of l i q u i d on t h e magnesia probe s u p p o r t . The pump w a s t h e n withdrawn from t h e molten L i C 1 , and t h e system was cooled t o room t e m p e r a t u r e i n o r d e r t o r e c o v e r t h e pump.

Examination r e v e a l e d

t h a t t h e q u a r t z v e s s e l and pump had s u s t a i n e d s e v e r e damage i n r e g i o n s

c o n t a c t e d by t h e vapor; however, t h e q u a r t z s u r f a c e s i n c o n t a c t w i t h molten

L i C l showed no s i g n of a t t a c k . Two q u a r t z pumps, similar t o t h e f i r s t b u t having s a p p h i r e check v a l v e s , were t h e n f a b r i c a t e d and t e s t e d w i t h molten L i C l a t 6 5 0 ~ ~I .n t h e t e s t i n v o l v i n g t h e second pump, t h e L i C l w a s a i r - d r i e d a t 225OC.

The pump

o p e r a t e d s u c c e s s f u l l y f o r a few h o u r s , but d i f f i c u l t i e s w i t h s h o r t c i r c u i t s i n t h e l e v e l probes prevented continued o p e r a t i o n .

The q u a r t z components

of t h e system showed evidences of g r a d u a l d e t e r i o r a t i o n .

A f t e r 7 days of

exposure, t h e q u a r t z w a s b a d l y e t c h e d and some areas appeared t o be ready t o disintegrate. i n good c o n d i t i o n .

However, t h e s a p p h i r e b a l l s used as t h e check v a l v e s were The e l e c t r i c a l s h o r t c i r c u i t s were a p p a r e n t l y caused

by a f i l m of L i C l covering t h e i n s u l a t o r s used t o s e p a r a t e t h e e l e c t r i c a l probes. The t h i r d q u a r t z pump w a s t e s t e d i n L i C l t h a t had p r e v i o u s l y been p u r i f i e d by c o n t a c t w i t h a Th-Bi s o l u t i o n a t

6 5 0 t~o ~remove o x i d e s .

molybdenum cup c o n t a i n i n g t h e Th-Bi s o l u t i o n w a s p l a c e d i n t h e bottom of

5 '7 t h e pump t e s t v e s s e l t o f u r t h e r p u r i f y t h e L i C l .

This pump o p e r a t e d

s a t i s f a c t o r i l y at s a t e s of 30 t o 125 ml/min f o r 16 d a y s , a f t e r which it

A t t h e time of shutdown, t h e pump was

w a s disassembled f o r i n s p e c t i o n ,

still o p o r a t i n g s a t i s f a z t o r i l y ; however, i n s p e c t i o n of t h e p m p and t h e

q u a r t z vessel showed evidence of c o n s i d e r a b l e a t t a c k o f t h e quartz i n t h e

h o t vapor r e g i o n .

The q u a r t z cornpoaents t h a t were submerged i n t h e l i q u i d ,

t h e molybdenum component 6 , t h e carbon-st e e l thermowell, and t h e s a p p h i r e ba3.3.s used as check v a l v e s a l l appex-ed t o be i n r e a s o n a b l y good c o n d i t i o n .

Discussions w i t h q u a r t z m a n u f a c t u r e r s and w i t h t h o s e who have had e x p e r i e n c e

w i t h q u a r t z equipment r e v e a l e d t h a t d e v i t r i f i c a t i o n ( i . e .

a change i n t h e

c r y s t a l s t r u c t u r e o f t h e q u a r t z ) i s a d i f f i c u l t y commonly encountered w i t h t h i s material at high temperature.

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

a c c e l e r a t e d by t h e p r e s e n c e of contaminants ( s u c h as L I C 1 ) on t h e starfw? of t h e q u a r t z .

The full e f f e c t of d e v i t r i f i c a t i o n i s not a p p a r e n t until

t h e quartz h a s cooled t o room t e m p e r s t w e .

a t t a c k i n our experiments.

T h i s a p p e a r s t o be t h e t y p e of

m e n p u r i f i e d LiCl i s u s e d , t h e r a t e of

d e v i t r i f i c a t i o n appears t o be s u f f i c i e n t l y low t o p e n n i t a q u a r t z p m p t o

be used f o r t h e metal t r a n s f e r experiment.

A pump u s i n g c a p t i v e bismuth p o o l s as check v a l v e s h a s been f a b r i c a t e d

of low-carbon s t e e l .

T h i s pump will be t e s t e d w i t h molten LiCl i n t h e n e a r

future.

8. ELECTROLYTIC CELL DEVELOPMENT: J. R . Hightover, J r . 1;.

E. McNeese

STATIC CELL EXPEHIMENTS M. S. Lin

W e r e p e a t e d an e a r l i e r experiment,30 which w a s c a r r i e d o u t i n an a l l -

metal c e l l t o d e t e - m i n e whether t h e p r e s e n c e of quartz i n static-cell t e s t s w a s involved i n t h e f o r m a t i o n of b l a c k material i n t h e salt.

v e s s e l was f a b r i c a t e d from an 1 8 - i n . s e c t i o n of m i l d - s t e e l ,

The c e l l

sched 40 p i p e .

One e l e c t r o d e was a 15-kg pool o f bismuth; t h e o t h e r w z s a l/h-in.-diam

m i l d - s t e e l rod l o c a t e d a t t h e center of' t h e v e s s e l and p l a c e d 1/2 t o 1. i n . above t h e bismuth p o o l .

Observations i n t h e s a l t phase were made u s i n g t h e

bismuth s u r f a c e as a m i r r o r t o reflect l i g h t t o a s i g h t g l a s s i n t h e t o p

flange of t h e vessel.

The e l e c t r o l ~ y t e , a m i x t u r e of LiF-BeF2

(66-34mole % ) ,

f i l l e d t h e v e s s e l t o a, l e v e l about 3 i.n. above t h e bismuth s u r f a c e . bismuth h a d been spal-ged with H

at 60ooc t o remove o x i d e s .

The

The c e l l

v e s s e l w a s e l e c t r i c a l l y i s o l a t e d from t h e hood and from t h e gas and water supply l i n e s i n o r d e r t h a t t h e bismuth p o o l (and hence t h e c e l l vessel.)

could be o p e r a t e d i n an anodic mannzr; t h e r e s i s t a n c e between t h e c e l l and

gl-ound w a s 2 x 10 R.

A dc v o l t a g e of 2 . 3 V impressed a c r o s s t h e elec-Lrodes f o r about 1. min,

w i t h t h e i r o n rod l o c a t e d 1./2 i n . above t h e bismuth ( t h e i r o n r o d w a s

c a t h o d i c ) , produced a c u r ~ e n tof about 16.8 A ; wher, t h e e l e c t r o d e isas

r a i s e d t o 1 in. above t h e bismuth s u r f a c e f o r about 2 m i n , t h e c u r r e n t decreased t o 1 5 . 6 A .

An i n c r e a s e i n v o l t a g e t o 2 . 5 V

produced a c u r r e n t

t h a t i n c r e a s e d from 19.0 4 t o 21.8 A over a p e r i o d of 7.5 min; t h e cathoclp c u r r e n t d e n s i t y d u r i n g t h i s time was about 1.8 'io 2 . 0 A/cm 2

charge t r a n s f e r r e d d u r i n g t h e r u n w a s 1.2,400C . 55OoC.

The t o t a l

The c e l l t e m p e r a t u r e was

During t h e passage o f e l e c t r i c c u r r e n t , t h e r e w a s no s i g n of t h e

dark materi-a1 t h a t had p r e v i o u s l y been s e e n ; duying t h e c e l l o p e r a t i o n , d e n s i t y g r a d i e n t p a t t e r n s were v i s i b l e , i n d i c a t i n g t h a t c o n v e c t i v e mixing was t a k i n g p l a c e i n t h e s a l t phase.

After the o p e r a t i o n had been

completed, the s a l t appeared 'io have a m o r e d i s t i n c t g r e e n c o l o r t h a n before.

Although t h e s a l t vas s l i g h t l y t u r b i d , it was s t i l l quiLe

transparent.

During t h e o p e r a t i o i l of t h e c e l l , m a t e r i a l was d e p o s i t e d on the i r o n cathode.

Some of the m a t e r i a l w a s m e t a l l i c and was probably not as dense

as t h e sa1.t s i n c e it formed n e a r t h e sa1.t-gas i n t e r f a c e and t e n d e d t o

s p r e a d out over t h e s u r f a c e of t h e s a l t .

The remainder o f t h e material

w a s b l a c k and n o n m e t a l l i c , and formed more uniformly over t h e submerged

p a r t of t h e s t e e l e l e c t r o d e . composition 9.0

ryt

% Re,

ti%acesof Fe a n d Bi.

follows. A s BeF

The d e p o s i t e d m a t e r i a l

1.7,O v t

% T , i , and 71.8

w t

(16.5 g ) had t h e

% F, and contai-ned

The f o r m a t i o n of such a d e p o s i t i s e x p l a h e d as

w a s reduced a t t h e cathode d u r i n g the c e l l o p e r a t i o n ,

t h e c o n c e n t r a t i o n of BeP i n t h e s a l t i n t h e v i c i n i . t y of t h e cathode 2 d e c r e a s e d . At t h e o p e r a t i n g t e m p e r a t u r e of 550째C, LiF b e g m to c r y s t a l l i z e when t h e BeF

r e d u c t i o n of BeF

FELS

c o n c e n t r a t i . o a reached 30 mole

%. F u r t h e r

accompanied by p r e c i p i t a t i o n of s o l i d LiF i n t h e

v i c i n i t y of t h e cathode. When t h e cathode was I"emoved from t h e c e l l , some of t h e LiF--BeF2 m i x t u r e w a s c a r r i e d wi.th t h e reduced- b e r y l l i u m .

59 If one assunes t h a t t h e L i w a s p r e s e n t as LiF and t h a * t h e remaining

F was a s s o c i a t e d w i t h Be as BeF2' t h e c a t h o d i c d e p o s i t c o n t a i n e d about 0 . 5 g o f Be metal (33% of t h e Be p r e s e n t in t h e d e p o s i t ) o r 0.11 gram S i n c e 0.129 e l e c t r i c a l e q u i v a l e n t w a s p s s s e d , t h i s

e q u i v a l e n t of Be.

r e p r e s e n t s a c u r r e n t e f f i c i e n c y of about 85% for beryllium r e d u c t i o n .

The c u r r e n t e f f i c i e n c y w a s p r o b a b l y a c t u a l l y c l o s e r t o 100%; however, t h e a d d i t i o n a l b e r y l l i u m was n o t r e c o v e r e d w i t h t h e c a t h o d i c d e p o s i t b u t f l o a t e d away from t h e cathode o n t h e surface of the s a l t .

Some p a r t i c u l a t e

material w a s n o t e d on t h e s a l t s u r f a c e when t h e c e l l was d i s m a n t l e d .

The f a c t t h a t t h e s a l t i n t h i s t e s t remained t r a n s p a r e n t i n d i c a t e s

t h a t quai?tz may be impol-tant i n t h e f o r m a t i o n of b l a c k m a t e r i a l i n t h e

salt.

However, t h e l a c k of a bismuth cathode i n t o which lithium could

have been reduced may have r e s u l t e d i n a system t o o d i f f e r e n t from p r e v i o u s c e l l s t o allow u s t o draw f i r m c o n c l u s i o n s .

THE PURIFICATION OF SALT BY CONTIflWOUS METHODS R. E. Lindauer L . E. McNeese STlDY OF

To d a t e , t h e molten s a l t r e q u i r e d f o r development work as well as f o r

t h e MSRE h a s been p u r i f i e d from h a m f ' u l contaminants (mainly s u l f u r ,

oxygen, and i r o n f l u o r i d e ) by a b a t c h p r o c e s s .

The c o s t of s a l t from t h i s

p r o c e s s ( c o n t a i n i n g natural l i t h i u m ) has averaged about $1600/ft3; less

I n A p r i l 1968, a commercial vendor submitted a 'oid of $ 2 6 6 0 / f t 3 on a 280-ft 3 q u a n t i t y of

t h a n 40% of t h i s c o s t i s due t o t h e c o s t o f materials. salt.

It i s b e l i e v e d t h a t t h e l a b o r c o s t s a s s o c i a t e d w i t h s a l t p u r i f i c a t i o n

can be reduced c o n s i d e r a b l y by u s e o f a continuous p r o c e s s f o r t h e most time-consuming o p e r a t i o n , which i s t h e hydrogen r e d u c t i o n of iron f l u o r i d e . Although t h e removal of s u l f u r and oxygen by t h e b a t c h p r o c e s s i s T a i r l y r a p i d , t h e r e would p r o b a b l y be advantages t o performing t h i s o p e r a t i o n i n continuous equipment a l s o . A packed column i n which molten s a l t and g a s can be c o n t a c t e d eounter-

c u r r e n t l y i s b e i n g i n s t a l l e d ( c e l l LB, second f l o o r of Bldg. 4505) t o

o b t a i n d a t a t h a t vill p r o v i d e t h e b a s i s f o r t h e d e s i g n o f a f u l l - s c a l e continuous s a l t p u r i f i c a t i o n f a c i l i t y .

Flooding s t u d i e s w i l l be made u s i n g

argon and hydrogen w i t h two d i f f e r e n t s a l t m i x t u r e s :

LiF-BeF:, (66-314 mole $ )

aad LiF-SeF -TnF

(72-16-12 mole % )

S t u d i e s of i r o n r e d u c t i o n and o x i d e

removal w i l l a l s o be made w i t h b o t h s a l t s .

Since b e r y l l i m f l u o r i d e with

a low sulfur c o n t e n t i s now w a i l a b l e , no s u l f u r removal work i s planfled,

9.1

P r e v i o u s Work on S a l t P u r i f i c a t i o n

A l l of t h e molten s a l t used i n Lhe m o l t e n - s a l t r e a c t o r p r o j e c t s a t OHNL up t o t h e p r e s e n t time h a s been prepared in small ( 2 - f t

) batch

31 A f t e r the raw m a t e r i a l s have been Slended and m e l t e d , the equipment. s u l f i d e s and o x i d e s are removed s i m u l t a n e o u s l y by a H,-HF 42

s p a ~ g eat 600째C.

'The t e m p e r a t u r e of the s a l t i s t h e n i n c r e a s e d t o about 700째C, and t h e

f l u o r i d e s of Fe and N i are reduced by c o n t a c t i n g t h e s a l t w i t h hydrogen.

Next, t h e s a l t i s passed through a s i n t e r e d nickel. f i l t e r .

ITGn

fluoride

r e d u c t i o n , t h e most time-consuming of t h e v a r i o u s s t e p s , r e q u i r e s a11out f o u r days of c o n t a c t i n g with hydrogen for a 2 - f t 3 babein.

Completion of

refhc'cion of t h e m e t a l fl.uorides i s determined by t i t r a t i o n of a sample

o f Lhe e f f l u e n t gas f o r F F conkent.

C o n s i d e r a t i o n o f continuous methods f o r use in t h e p u r i f i c a t i o n of

m o l t e n salt, m i x t u r e s began i n 1967 w i t h a p r e l i m i n a r y coneeptiml. k s i g n of a serniconti.nuous p i l o t p l a n t by t h e MIT P r a c t i c e School. 32

~n a ten-

t a t i v z design t h a t was proposed f o r a 0.25-ft 3/hr piJ.ot p l a n t , packed

columns were suggested f o r t h e h y d r o f l . u o r i n a t i o n amd r e d u c t i o n s t e p s .

d e t a i l e d d e s i g n of t h e p l a n t was not p o s s i b l e because of the l a c k of r a t e d a t a f o r t h e s t e p s involved.

During the f o l l o w i n g y e a r , two s e r i e s of

experiments %reremade by t h e MIT P r a c t i c e School 33""

f o r s t u d y i n g .the

r e d u c t i o n of i r o n f l u o r i d e i n m o l t e n - s a l t m i x t u r e s by c o u n t e r c u r r e n t cont a c t w i t h hydrogen i n a packed column.

Although o n l y a f e w runs were made

and equipment performance w a s n o t completely sati s f a c t o r y , s i g n i f i c a n t r e d u c t i o n of t h e i r o n f l u o r i d e was shown..

The r e s u l - t s sugges-Led t h a t t h e

r e d u c t i o n r a t e i s f i m t o r d e r w i t h r e s p e c t t o i r o n f l u o r i d e concentra.tion and t h a t t h e r a t e i s c o n t r o l l e d by the amount of i n t e r r a c i a l area t h a t i s

p r e s e n t between t h e salt; and t h e hydrogen.

It w a s recomiended .that

a d d i t i o n a l s t u d i e s he made t o e s t a b l i s h t h e r a t e - c o n t r o l l i n g mechanism

more f i r m l y .

I t w a s a l s o s u g g e s t e d 'that (1.) more e f f e c t i v e p u r i f i c a t i o n

of t h e hydrogen i s n e c e s s s r y , ( 2 ) f u t u r e r u n s should be made w T t h packing

m a t e r i a l s o t h e r t h a n York Demister mesh, and ( 3 ) t h e colunn s h o u l d be operated close t o t h e loading or flooding point. 9.2

Experimental- Equipment

A s i m p l ' i f i e d f l o w s h e e t f o r t h e p r e s e n t e x p e r i m e n t a l equipment i s

shown i n F i g . 22.

Molten s a l t i s f e d t o t h e column by p r e s s u r i z i n g t h e

f e e d t a n k w i t h apgon a t a c o n t r o l l e d r a t e .

The s a l t f 7 . o ~r a t e i s s e t by

t h e argon flow r a t e and i s determined by t h e r a t e of d e p l e t i o n of s a l t The hydrogen i s p r e h e a t e d b e f o r e e n t e r i n g t h e c o l ~ m m

f r m t h e feed tank. by

1.5-in.-diani,

spheres.

2l+-in.-long h e a t e r I " i l l e d with l/b-in,-diam

nickel

The s a l t from t h e column f l o w s t h r o u g h a g a s - s e a l l o o p and a

s a l t f i l t e r c o n s i s t i n g o f a removable 2.75- b y 1 2 - i n .

m e t a l c a r t r i d g e w i t h a medn p o r e s i z e of 50 1-1.

nickel Feltmetal f i b e r

The s a l t p a s s e s t h r o u g h a

flowing s t r e a m sampler b e f o r e e n t e r i n g t h e r e c e i v e r t a n k .

The gas s t r e a m

l e a v i n g t h e column can be t h r o t t l e d i f n e c e s s a r y t o d e p r e s s t h e s a l t - g a s i n t e r f a c e t o a p o i n t below the bottom of t h e column.

A sample o f t h e gas

stream can be withdrawn f o r continuous d e t e r m i n a t i o n of t h e HpO and HF I

contents.

The stream t h e n p a s s e s t h r o u g h a NaF t r a p and

a i

absolute f i l t e r .

Packed Colimn. - The column w a s f a b r i c a t e d from 1,25-in.-diam

carbon n i c k e l p i p e and can b e o p e r a t e d a t t e m p e r a t u r e s up t o 750*C. packed s e c t i o n i s 81 i n . l o n g and c o n t a i n s l / b x 1/4 x l / l G - i n .

Raschig r i n g packing.,

lowThe

nickel

There axe deentrainment s e c t i o n s o f 3-in, --dim p i p e

a t each end, and a 2-ft-long

s e c t i o n of 1/2-in.-dim-

p i p e below t h e column

f o r deentrainment of hydrogen i n c a s e t h e i n t e r f a c e i s d e p r e s s e d by a h j g h p r e s s u r e drop t h r o u g h t h e column.

A d i f f e r e n t i a l - p r e s s u r e transmitter

having a r a n g e of 0 t o 50 i n . H 0 i s connected t o t h e gas i n l e t and o u t l e t

l i n e s t o p r o v i d e d a t a on liquid holdup and f l o o d i n g .

i n t h e absence o f

gas flow t h r o u g h t h e column, t h e s a l t - g a s i n t e r f a c e i s l o c a t e d 3.4 i n .

above t h e hydrogen i n l e t ; t h e i n t ; e r f a c e can b e d e p r e s s e d below t h e i n l e t

by i n c r e a s i n g t h e p r e s s u r e a t t h e t o p of the coLumn o r by an i n c r e a s e i n t h e p r e s s u r e drop a c r o s s t h e column.

The column i s h e a t e d by r e s i s t a n c e

h e a t e r s having a t o t a l h e a t i n g c a p a c i t y of 3 kW.

S a l t Feed and Receiver Tanks. - The f e e d and r e c e i v e r t a n k s have, i n

each c a s e , an i n s i d e d i a m e t e r of 1 0 . 2 5 i n . , a h e i g h t o f 1 5 i n . , and a volume of 21 l i t e r s .

The l / h - i n . - t h i c k

walls and t h e 1 - i n . - t h i c k

f l a t ends a r e

O R N L DING 70-1104EI

1 I I S AMPLER ..... .

RECEIVER

Fig. 22. Simplified Process Flowsheet for Molten-Salt P u r i I â&#x20AC;? i e a t i o n Studies.

63 made of low-carbon n i c k e l .

These p r o c e s s v e s s e l s r e q u i r e a p p r o v a l f o r use

as p r e s s u r e v e s s e l s s i n c e t h e i r d i a m e t e r s are g r e a t e r t h a n 5 i n . and t h e o p e r a t i n g p r e s s u r e Is g r e a t e r t h a n 5 p s i g .

(The v e s s e l s have been approved

by t h e ORNL P r e s s u r e Vessel Committee f o r u s e a t 25 p s i g and

650%)

l i e a t e r s on t h e column f e e d l i n e are used t o h e a t t h e s a l t t o a t e m p e r a t u r e o f 700 t o

75OoC b e f o r e it e n t e r s t h e column.

P r e s s u r e r e l i e f v a l v e s on t h e

argon and hydrogen supply systems a r e used t o l i m i t t h e maximum p r e s s u r e t o 25 p s i g .

The t a n k s a r e h e a t e d by e l e c t r i c a l r e s i s t a n c e h e a t e r s equipped

with temperature c o n t r o l l e r s t o permit unattended heatup.

Each tank h a s a

bubble-type l i q u i d - l e v e l Instrument and b o t h w e l l - and surface-mounted thermocouples. S a l t Samplers.

- Samplers

are provided on t h e s a l t f e e d t a n k and i n

t h e l i n e e x i t i n g from t h e s a l t f i l t e r .

These samplers c o n s i s t o f a b a l l

v a l v e t h r o u g h which a sample c a p s u l e c a n b e lowered i n t o t h e l i q u i d . c a p s u l e i s 3/16 i n . I D and 1 . 5 i n . l o n g , and has a 25 a t t a c h e d t o t h e bottom,

The

metal f i b e r f i l t e r

Vacuum i s a p p l i e d through a c a p i l l a r y t u b e a t t a c h e d

t o t h e t o p i n o r d e r t o o b t a i n a f i l t e r e d salt sample.

-O. f f - G a s Analyzers. - A

sample of t h e column off-gas s t r e a m can b e

passed t h r o u g h a water and/or a hydrogen f l u o r i d e a n a l y z e r a t t h e yate

of' about 5 cm3 /min. small "Dyna-Vac"

Flow t h r o u g h t h e s e i n s t r u m e n t s i s o b t a i n e d by a

gas pump.

The w a t e r a n a l y z e r i s t h e same i n s t r u m e n t

t h a t w a s used i n t h e MSRE Fuel P r o c e s s i n g F a c i l i t y . 3 5

Hydrogen f l u o r i d e

i s removed from t h e d i l u t e d s m p l e by a sodium f l u o r i d e t r a p b e f o r e pas-

s i n g t h r o u g h an e l e c t r o l y t i c m o i s t u r e c e l l .

A reference l e g with a similar

t r a p and c e l l p r o v i d e s a compensated system w i t h a s i n g l e r e a d o u t .

The in-

strument i s q u i t e s e n s i t i v e , and t h e i n j e c t i o n of gas c o n t a i n i n g 250 ppm o f water produces a r a p i d r e s p o n s e .

36 h a s a s e p a r a t e sample d i l u t e r w i t h a h e a t e d c a p i l l a r y t u b e t h a t withdraws a 5-crn3 sample each minute; t h e The hydrogen f l u o r i d e monitor

sample i s d i l u t e d w i t h argon t o produce a flow r a t e of" 1000 cm / m i n .

'The d i l u t e d sample is scrubbed with an acetic acid s o l u t i o n i n t h e monj-

t o r , and t h e s o l u t i o n i s analyzed by use of' a n aluminum-platinum electrol-

ysis cell.

9.3

Gas Supply and P u r i f i c a t i o n Sys-tems

Argon.. -A~i-gon i s s u p p l i e d t o a p u r i f i c a t i o n systcm from a s i x - c y l l n d e r

manifold. JIOW-Q-~

Oxygen i s removed by a 6 - i n . - d i m ,

24--in. -high trap charged w i t h

(copper-coated a h m i n u n ) , which has a t o - t a l oxygen c a p a c i t y of 7 ml.

The oxygen c a p a c i t y a t 100 t i m e s t h e rnsximwn

(STP) p e r gram of pa.ck.ing.

argon f l o w rate expected (maximum expected r a t e ,

6' l i t e r s / m i n )

i.8 1. r n l of

cxygen p e r gram of absorbent, w i t h a removal e f f i c i e n c y of 98%, The

expected oxygm c o n c e n t r a t i o n i n t h e u n p i i r i f i e d argon i s about 1 0 ppm; --.--.-Lfication

;--?;-?,

system has a n expected l i f e o f a t l e a s t I+ months

and should reduce the oxygen c o n c e n t r a t i o n i.n t h e p u r i f i e d gas t o about

0.02 ppm.

The oxygen c o n t e n t of t h e nrgon i s measured by a Teledyne Model.

306 W Oxygen Trace Analyzer, which u s e s a w e t g a l v a n i c c e l l w i t h s i l v e r lead electrodes.

The a n a l y z e r can be used for d e t e x m l n i n g t h e oxygen

e o n c e n t r a b i o n i n e i t h e r the p u r i f i e d . or i.inpurified argon.

!dater i s removed. from t h e argon by one ol" two Molecular S i e v e

traps

t h a t &re arranged i n part~allelto all-ow o p e r a t i o n d u r i n g regenel-at inn of

one o f t h e t r a p s .

The traps c o n s i s t of a 42-in.-long

ta-ined i n the annulus between a ?-in.-diam

packed section con-

p i p e :and a 2-<n.-diam p i p e t h a t

sisrrounds t h e h e a t e r s used f o r r e g e n e r a t i o n o f the t r a p s .

Each t r a p con-

3 taiiis about 0.4 f t o f t y p e &A Molecular S i e v e and can reduce t h e vater

c o n c e n t r a t i o n i n a, 6 - i i t e ~ l m i n a-rgois stream from 100 ppm t o 1 ppm f o r a,

p e r i o d o f 300 days.

The watel- c o n t e n t of t h e argon i s measured b e f o r e ami9

a f t e r p u y i f i c a t i o n by a Panametrics model 1000 hygrometer, which u s e s an aluminum oxi.de s e n s o r p l a c e d d i r e c t l y i n t h e flowing gas stream. Hydrogen. - Hydrogen i s s u p p l i e d t o one of two p u r i f i c a t i o n s y s t e m

from a four-cyl-inder manifold.

One p u r i f i c a t i o n system, c o n s i s t i n g o f a

flow r a t e s up to 18 l i t e r s h i n .

In t h e o t h e r p u r i f i c a t i o n System, which

S e r f a s s Hydrogen P u r i f i e r (pa1.ladiuri-1 membrane) , w i l l p r o v i d e hydrogen a t i.s

used for h i g h e r f l o w r a t e s , t h e hydrogen is passed through a Deoxo u x i t

where oxygen i.s converted to w a t e r , and a Molecular S i e v e t r a p w i t h a capaci.ty similar to t h a t of t h e t r a p on t h e argon supp'1.y.

The Deoxo u n i t

h a s a d i a m e t e r of 2 , 5 Ifn., a l e n g t h of 1 2 . 5 in., and a rated maximum c a p a c i t y o f 50 l i t e r s of hydrogen

Ilydrogerz

Fluoride.

(maxixnLlsri

oxygen c o n t e n t , 3%) per minute.

Hydrogen fluox-ide i s v a p o r i z e d from a. t a n k

having a 3 5 - l i t e r working volume.

The t a n k i s h e a t e d i n a water bath, and

t h e p r e s s u r e i n t h e t s n k i s s e t by controll.ing t h e b a t h t e m p e r a t u r e .

The

v a p o r i z e d hT f l o w s through a c u b i c l e , m a i n t a i n e d a t 100째C, t h a t contaFns a

pressure t r a n s m i t t e r , an I.fF f l o w c o n t r o l v a l v e , four c a p i l l a r y t u b e s and

a d i f f e r e n t i a l - p r e s s u r e t r a n s m i t t e r for d e t e r m i n i n g HF flow r a t e , and

Hastings mass f l - o m e t e r . 3

of 1000 cm'/min,

?500 em3/min.

The H a s t i n g s flowmeter h a s a maximun FLOW r a t e

w h i l e t h e c a p i l l z r i e s have m a x i m u m fl.ow r a t e s of 250 t o

The flow of HI? can be t e r m i n a t e d from t h r e e d i f f e r e n t

1-ocations in t h e o p e r a t i n g area i n c a s e of' an ernergcncy. Sulfzrr i s removed from t h e v a p o r i z e d

diam p i p e packed w i t h n i c k e l wool.

HIT

by passing it through

An 18-in.-long

:.t

2-in.-

s e c t i o n of the p i p e

c o n t a i n s t i g h t l y compressed wool. and Fs h e a t e d t o 6gSO째C.

A 2b-in.-long

s e c t i o n of n i c k e l wool l o c a t e d doymstrearn of t h e h e a t e d s e c t i o n i s used t o

remove p a r t i cixlakes from the gaseoi-is EIF.

9.4 I n s t a l l a t i o n of Equipment and I n i t i a l Checkout The equipment (shown i n F i g s . 23-25 b e f o r e a d d i t i o n o f therrnai

i n s u l a t i o n ) w a s mounted i n a 30 i n . x 30 i n . x 13-ft-high fram? for

i n s t a l l a t i o n i n cell

on t h e second f l o o r of Bldg. L505.

Instruments

for measuring t h e liqi-lid l e v e l s in t h e s a l t f e e d and r e c e i v e r t a n k s , t h e

p r e s s u r e a t t h e t o p of t h e col1m.n and above t h e salt filter, and t h e

d i f f e r e n t i a l pressure a c r o s s bhe column are a l s o l o c a t e d in t h e cell. a d d i t i o n , t h e c e l l c o n t a i n s off-gas

measuring t h e ITF and t h e II,O L

filters

i n - l i n e instruments f ~ r

c o n t e n t s of t h e off-gas stream from t h e colimn,

an& a. sodium fluor-ide trap f o r d i s p o s a l of excess ISF.

The equipment i s

operated from t h e .mea j u s t o u t s f d e the c e l l on the second floor, where

r a t e and t h e t h e r o t a m e t e r s are l o c a t e d f o r c o n t r o l l i n g t h e hydrogen f l ~ w

argon f l o w r a t e s for purges and p r e s s u r i z a t i o n o f t h e salt f e e d t a n k a

panelboard i s shosm i n Ffp. 26.

A s e p a r a t e pa.nelboard,

S~GTJII

The

i n '.l'ig. 27,

c o n t a i n s h e a t e r c o n t r o l l e r s f'or t h e equipment, as w e l l as t h e recorders

a n d indicators f o r ternpcratm-e, l i q u i d l-evel, and p r e s s w e

A f t e r completion of t h e p i p i n g b u t p r i o r t o a p p l i c a t i o n of i n s u l a t i o n

to t h e system, t h e equipment was l e a k t e s t e d . a t 1 5 p s i g and rocm

t e m p e r a t u r e , u s i n g helium and n thermal e c n d u c t i v i t y leak d - e t e c t o r capa'ale

of d e t e c t i n g a l e a k rcltc of l e s s t h a n 0.001 cm /set. The leak r a t e for t h e f i n d system TUTBSabout 0.07 cm 3/see a f t e r a l l d e t e c t a b l e l e a k s had be en re p s i r ed

.___,_..._..I....-....-..-.

66 O R N L P H O T O 98475A

Fig. 23. Top V i e w of Salt Purification Equipment Before Addition of Thermal Insulation.

VELP86 OlOHd 1NtlO

68 O R N L PHOTO 98476A

Fig. 25. Insulation.

Salt Purification Equipment Before Addition of Thermal

PHOTO 98474

9.t 3

L L '1

Fig. 26. Panelboard for Salt Purification Equipment. Temperature, level, and pressure recorders and heater controls are included.

c I

A n t i c i p a t e d Experiments and Operating Procedures

9.5

Experimental Program, - T h e

system w i l l be charged i n i t i a l l y w i t h

about 1 5 l i t e r s of LIF-BeF2 (66-34 mole % ) , and w i l l b e o p e r a t e d w i t h argon and hydrogen t o determine t h e column f l o o d i n g r a t e a t s e v e r a l s a l t rlow r a t e s .

The s a l t w i l l t h e n b e t r e a t e d w i t h a H2-HF

f e e d t a n k t o remove o x i d e s .

mixture i n t h e

The f l o o d i n g t e s t s w i l l be r e p e a t e d i n o r d e r

t o determine t h e e f f e c t of o x i d e i n t h e s a l t on f l o o d i n g .

Subsequently,

i r o n f l u o r i d e w i l l be added t o t h e s a l t , and t h e s a l t w i l l be c o u n t e r c u r r e n t l y c o n t a c t e d w i t h hydrogen a t s e v e r a l gas and s a l t flow r a t e s t o o b t a i n mass t r a n s f e r data f o r r e d u c t i o n of t h e i r o n .

After these data

have been c o l l e c t e d , a p o r t i o n of t h e i n i t i a l l y charged s a l t w i l l be withdrawn from t h e system and s u f f i c i e n t LiF and LiF-ThF

4 e u t e c t i c (73-27

mole % ) w i l l be added t o y i e l d s a l t having t h e composition of 72-16-12 ,mole

% LiF-BeF2-ThF4.

Flooding and i r o n f l u o r i d e r e d u c t i o n t e s t s w i l l be

r e p e a t e d w i t h t h e new s a l t m i x t u r e .

Removal of o x i d e from t h e s a l t by

c o u n t e r c u r r e n t c o n t a c t w i t h a H -HF m i x t u r e i n t h e column w i l l a l s o be 2 i n v e s t ig a t ed

Experimental Method.

- The

f l o o d i n g d a t a w i l l be o b t a i n e d by main-

t a i n i n g a c o n s t a n t s a l t f l o w r a t e t h r o u g h t h e column w h i l e t h e g a s f l o w r a t e is increased i n several steps.

The p r e s s u r e drop a c r o s s t h e column

a t each g a s f l o w r a t e w i l l be r e c o r d e d ; i n c r e a s e s i n t h e g a s f l o w r a t e w i l l be c o n t i n u e d u n t i l a s h a r p i n c r e a s e i n column p r e s s u r e d r o p i s observed. experiment.

The column t e m p e r a t u r e w i l l b e m a i n t a i n e d at 7OO0C d u r i n g t h e I f subsequent i r o n f l u o r i d e r e d u c t i o n t e s t s show t h a t a

h i g h e r t e m p e r a t u r e i s n e c e s s a r y , f l o o d i n g t e s t s w i l l a l s o b e made a t t h e higher temperature.

Reduction runs w i l l be made i n a similar manner a f t e r

i r o n f l u o r i d e h a s been added t o t h e s a l t .

F i l t e r e d s a l t samples w i l l

be t a k e n from t h e s a l t i n t h e f e e d t a n k b e f o r e and a f t e r a run.

Several

f l o w i n g stream samples w i l l be withdrawn d u r i n g each r u n . Data o b t a i n e d by a n a l y z i n g t h e samples for i r o n w i l l b e used for

c a l c u l a t i n g v a l u e s of t h e mass t r a n s f e r c o e f f i c i e n t s f o r t h e system.

The

f l u o r i d e monitor w i l l p r o v i d e a check on t h e e x t e n t of i r o n r e d u c t i o n achieved.

I n t h e o x i d e removal t e s t s , t h e water a n a l y z e r i n t h e column

o f f - g a s stream w i l l be used for d e t e r m i n i n g t h e amount of o x i d e removed

from t h e s a l t .

72 Operating Pr0cedure.s.

-A

t y p i c a l run f o r t e s t i n g i r o n f l u o r i d e

w i l l c o n s i s t of t h e f o l l o w i n g s t e p s : Heat t h e system t o o p e r a t i n g t e m p e r a t u r e . Add a weighed amount of FeF2 ( i f n e c e s s a r y ) t o t h e s a l t i n t h e

f e e d t a n k , and s p a r g e f o r s e v e r a l hours. Sample t h e salt i n t h e f e e d t a n k . A c t i v a t e t h e f l u o r i d e monitor; s t a r t t h e gas sample pump, h e a t t h e sample flow c a p i l l a r y , s e t t h e sample and d i l u e n t gas flow

rates, and s e t t h e scrubber s o l u t i o n flow rate. Check t h e hydrogen supply system; h e a t t h e S e r f a s s membrane i f

it i s t o be used. Check t h e O2 and H20 c o n t e n t s of t h e argon and hydrogen supply. Check t h e instrument purge rates. S t a r t t h e hydrogen flow a t t h e s p e c i f i e d r a t e . P r e s s u r i z e t h e f e e d t a n k and a d j u s t t h e p r e s s u r i z i n g argon f l o w r a t e t o p r o v i d e t h e s p e c i f i e d salt flow r a t e . Record t h e data on column t e m p e r a t u r e , flow r a t e s , column p r e s s u r e drop, s a l t head above t h e f i l t e r , p r e s s u r e at t h e t o p of t h e column, and f l u o r i d e c o n c e n t r a t i o n i n t h e e x i t g a s s t r e a m . Withdraw flowing stream s a l t samples p e r i o d i c a l l y . When t h e s a l t supply i n t h e f e e d t a n k i s exhausted, vent t h e f e e d t a n k and t e r m i n a t e t h e flow of hydrogen. Purge t h e system of hydrogen. T r a n s f e r t h e s a l t i n t h e r e c e i v e r v e s s e l back t o t h e f e e d t a n k . Sparge and sample t h e f e e d t a n k .

73 10. SEC4Iâ&#x20AC;&#x2122;CONTIRVOUS HEDIJCTIVE: EXTRACTION EWERIMEXTS

IN A MILD-STEEL FACILITY

B. A. Hannaford C . W. K e e L, E. MeNeese

A new column, packed w i t h 1/4-in.

molybdenum Raschig r i n g s , was

i n s t a l l e d i n t h e system, and minor changes were made i n some of the

piping.

Three s u c c e s s f u l hydrodynamic experiments were performed i n which

bismuth and molten s a l t were c o n t a c t e d c o u n t e r c u r r e n t l y ,

The r e s u l t s are

i n e x c e l l e n t agreement w i t h a f l o o d i n g c o r r e l a t i o n developed from work with t h e mercury-water system.

Data from a hydrodynamic experiment i n

which s a l t f l o w o n l y w a s used e s t a b l i s h e d t h a t t h e p r e s s u r e d r o p a c r o s s t h e nsw column w a s approximately equal t o t h a t > r e d i e t e d from a

literaturc3 c o r r e l a t i o n .

1-0.1 Equipment M o d i f i c a t i o n s

Operating e x p e r i e n c e s i d t h t h e o r i g i n a l column and examination of t h e column following i t s removal suggested t h e need f o r minor changes i n t h e column d e s i g n .

Of p r i n c i p a l importance was the s u b s t i t u t i o n of l / b - i n .

Raschig r i n g s for s o l i d l / b - i n .

a col.imn packed w i t h 1 / 4 - i n .

right circular cylinders.

I n s t a l l a t i o n of

R a s c h i g r i n g s was advantageous a t this t i m e

i.n t h a t i t provided a column whose c h a r a c t e r i s t i c s sholild be a l t e r e d on1.y

s l i g h t l y by d e p o s j t i o n o f s m a l l m o u n t s of i r o n i n t h e colunin. The new column had a n inside d i a m e t e r of 0 . 8 2 i n . and

of 2J-c i n . , excluding end s e c t i o n s . 1.?-in.-I.ong

Each of the end sections c o n t a i n e d a

packed s e c t i o n c o n s i s t i n g of a t r a n s i t i o n from t h e 0 . &-in.

colimn d i m e t e r to t h e 1 . 6 - i n .

end s e c t i o n d i a m e t e r .

lâ&#x20AC;&#x2122;he voicl f r a c t i o n of t h e column w a s

measurement.

pack.&. length

0.84, as determined

by direct

An X-ray r a d i o g r a p h of -the new column ( F i g . 28) confirmed

t h a t t h e molybdenum Raschig r i n g s were uniformly d i s t r i b u t e d .

IChe 1./4-in.

aod 3/8-in.-long m i l d - s t e e l r i n g s , which were tack-velded t o t h e s l o t t e d

support plate i n order t o p r e v e n t -the bottom l a y e r of mol.ylt,denum r i n g s

Prom sealring t h e s l o t s , are not c l e a r l y shown.

Measurements o f t h e

pressure drop across the colimn were made w i t h argon at :room t e j p e r a t u r e i n o r d e r t o e s t a b l i s h a r e f e r e n c e c o n d i t i o n f o r future cornparison.

I n o r d e r t o minimize entrainment of b i s m u . t h into t h e s a l t rece?ver,

t w o changes were made at t h e t i m e the column was r e p l a c e d :

(1) t h e h e i g h t

ORNL DWG 70-4548Rl

SALT INLET

2 7 tn

Fig. 28. X-Ray Radiograph of Packed E x t r a c t i o n Column Before Ins t a l l a t i o n . The column, which has an i n s i d e diameter o f 0.82 i n . , i s packed with 1 / 4 - i n . Raschig rings. Measured void f r a c t i o n , 0.84.

75 o f t h e d i s e n g a g i n g s e c t i o n o f t h e column w a s i n c r e a s e d t o 3.5 i n . , and ( 2 ) t h e e n t r a i n m e n t d e t e c t o r w a s a l t e r e d s l i g h t l y t o improve t h e sepa r a t i o n o f bismuth from t h e e n t e r i n g s a l t . 10.2

Treatment of Bismuth and S a l t ; Adjustment of Zirconium D i s t r i b u t i o n R a t i o

P r i o r t o t h e f i r s t hydrodynamic experiment (HR-9) i n t h e new column,

t h e combined s a l t and bismuth phases were sparged w i t h about 300 g-moles

of 30% HF i n hydrogen d u r i n g a 20-hr o p e r a t i o n f o r t h e removal of p o s s i b l e oxide contaminants.

T h i s w a s followed by a 6-hr hydrogen s p a r g e ( f o r re-

moval o f HF) and t h e a d d i t i o n o f m e t a l l i c thorium t o reduce FeF i n t o t h e bismuth phase.

and ZrF4

A d d i t i o n of zirconium t o t h e bismuth i s r e p o r t e d

t o i n h i b i t t h e mass t r a n s p o r t o f i r o n - a i n earlier

operation^.^^

s o u r c e of i r o n d e p o s i t s observed

Samples o f bismuth and s a l t t a k e n 24 hr a f t e r

a d d i t i o n of t h e i n i t i a l 154 g o f thorium showed t h a t most of t h e i r o n b u t almost none o f t h e zirconium had been reduced.

An a d d i t i o n a l

157 g

o f t h o r i u m w a s added, and samples ( f i l t e r e d and u n f i l t e r e d ) were t a k e n of each phase 90 h r l a t e r .

A n a l y s i s of t h e bismuth r e v e a l e d t h e p r e s e n c e

o f 240 ppm of Th, 30 ppm o f L i , and 91 ppm of Zr.

The c o n c e n t r a t i o n of

l i t h i u m i n t h e bismuth w a s i n good agreement w i t h t h e c a l c u l a t e d equil i b r i u m v a l u e based on t h e thorium c o n c e n t r a t i o n , and t h e zirconium c o n c e n t r a t i o n i n t h e bismuth accounted f o r more t h a n 70% o f t h e zirconium i n v e n t o r y i n t h e system.

The s a l t and bismuth were judged t o be i n sat-

i s f a c t o r y c o n d i t i o n t o permit hydrodynamic experiments t o be c a r r i e d o u t i n t h e new column; t h e bismuth c o n t a i n e d about 90 plpm of zirconium, and t h e s a l t had a l o w i r o n c o n t e n t ( ~ 6 ppm). 0

10.3

Hydrodynamic Experiments HR-9,

Three s u c c e s s f u l hydrodynamic experiments

-10, -11, and -12

(HR-9, -10, and -11) were

made w i t h t h e new column, y i e l d i n g f l o o d i n g d a t a i n good agreement w i t h v a l u e s p r e d i c t e d from t h e f l o o d i n g c o r r e l a t i o n t h a t w a s developed from s t u d i e s w i t h a mercury-water system.

S a l t and bismuth were t r a n s f e r r e d

from t h e t r e a t m e n t v e s s e l t o t h e i r r e s p e c t i v e f e e d t a n k s j u s t p r i o r t o each r u n , and were t h e n c o u n t e r c u r r e n t l y c o n t a c t e d i n t h e column b e g i n n i n g a t a f l o w r a t e o f about 60 ml of each phase p e r minute.

The

flow r a t e of one o f t h e p h a s e g o r o f b o t h p h a s e s , w a s t h e n i n c r e a s e d

76 i n c r e m e n t a l l y u n t i l t h e column flooded.

Following each r u n , t h e s a l t and t h e bismuth were t r a n s f e r r e d t o t h e t r e a t m e n t v e s s e l . They were r e t u r n e d from t h i s v e s s e l t o t h e f e e d t a n k when a subsequent run was made.

Flooding

rates were d e f i n e d as t h o s e t h a t r e s u l t e d i n a c o n t i n u a l l y i n c r e a s i n g

p r e s s u r e drop a c r o s s t h e column or a p u l s a t i n g f l o w of s a l t and bismuth through t h e column. The flow r a t e d a t a o b t a i n e d during t h e t h r e e hydrodynmic experiments a r e summarized i n Table

The recorded time i n t e r v a l s of l e s s t h a n 8 min

r e s u l t e d from a v a r i e t y of r e a s o n s .

A t f l o o d e d o r near-flooded

conditions,

i t w a s u s u a l l y impossible t o m a i n t a i n a c o n s t a n t flow rate f o r each phase. A l s o , near t h e end of an experiment and a t h i g h 1:iv

rates, t h e supply of

bismuth o r s a l t l i m i t e d t h e time a v a i l a b l e . The d a t a from Table 4 are p l o t t e d as t h e s q u a r e r o o t of t h e s u p e r f i c i a l v e l o c i t y of each phase i n F i g . 29. bismuth--molten

The p r e d i c t e d f l o o d i n g curve f o r t h e

s a l t system, developed on t h e b a s i s of an assumed c o n s t a n t

s l i p v e l o c i t y between t h e phases,

38 i s shown f o r comparison.

The

experimental p o i n t s for nonflooded o p e r a t i o n l i e below t h e p r e d i c t e d

f l o o d i n g curve, and t h e p o i n t s f o r f l o o d e d c o n d i t i o n s l i e above t h e curve.

Thus, t h e data provide an e x c e l l e n t v e r i f i c a t i o n o f t h e f l o o d i n g c o r r e l a t i o n developed e a r l i e r . cylindrical

The data o b t a i n e d w i t h 1 / 4 - i n .

solid

packing, r e p o r t e d p r e v i o u s l y , a l s o a g r e e w i t h t h e p r e d i c t e d

f l o o d i n g curve.

However, t h e range o f f l o w rates i n v e s t i g a t e d w i t h t h e

s o l i d packing d i d n o t a l l o w such c o n c l u s i v e c o n f i r m a t i o n of t h e p r e d i c t e d curve as i s shown i n F i g . 29. Reference p r e s s u r e drop measurements f o r salt flow only were made

as t h e p r i n c i p a l o b j e c t i v e of run HR-12. Measurement of t h e small

p r e s s u r e drop expected (<lo i n . H20) r e q u i r e d t h a t t h e b i smut h - s a l t

i n t e r f a c e a t t h e bottom of t h e column b e d e p r e s s e d below t h e s a l t i n l e t .

T h i s w a s accomplished by r o u t i n g t h e argon off-gas flow t h r o u g h a mercury

seal i n o r d e r t o p r e s s u r i z e t h e t o p of t h e column, t h e s a l t overflow sampler, and t h e s a l t r e c e i v e r .

Observed p r e s s u r e drops through t h e

column were 2 , 2.5, and 5 i n . H20 a t s a l t f l o w r a t e s of 68, 127, and 244 ml/min, r e s p e c t i v e l y , as compared w i t h v a l u e s of 0.5, 1, and 2 i n . H 0 2 p r e d i c t e d by t h e Ergun e q u a t i o n . This w a s r e g a r d e d as a s a t i s f a c t o r y check of t h e p r e d i c t e d v a l u e s s i n c e t h e measured v a l u e s were o b t a i n e d as t h e d i f f e r e n c e between two l a r g e numbers.

rl I

a m

d ld

0 r-i

ffi

ffi k 0 k

ld Ld

-P 0

"2 k

x a 0

a x x 4-r 0

CI)

-3

a, ri

2 3

r--1

I+

M 0

L n r-

0 cc)

M r-i

w M

r-i

cu cu cu

L n r-i r-- cu d

,---I rl

L n

r-i

cn c n m

0 n

ffl

4 a rl 0

P P

k id PI

M Ln

i-I (u

i i

t--1

'7 8

ORNL DWG 70-14715 SALT FLOW, ML/MIN IO0 200 300

50 I

400 I

500 I

600

7o0700

PREDICTED FLOODING CURVE vCli2

+ vD1/*= 19.7, (FT/HR)~/*

A FLOODED 0 NONFLQODEO

0 0

F i g . 29. Flooding Data f o r t h e Bismuth-Salt System Compared w i t h t h e Flooding Curve P r e d i c t e d from Data from a Mercury-Water System.

a9 1 0 .]-I

Maintenance of Equipment

The amount of maintenance work r e q u i r e d during t h i s p e r i o d was s m a l l ; t h e r e were no i n s t a n c e s of i r o n d e p o s i t i o n and hence no formation o f p l u g s .

Two t r a n s f e r l i n e s f a i l e d , r e l e a s i n g a v e r y small amount of s a l t .

A salt

t r m s f e r l i n e from t h e t r e a t m e n t vessel developed a l e a k , a p p a r e n t l y due

t o a i r o x i d a t i o n of t h e s t e e l t u b i n g on t h e o u t s i d e of a bend.

A hole

developed i n a weld between t h e s a l t sampler and t h e s p e c i f i c g r a v i t y p o t ; t h i s Cailure was probably due t o contamination of t h e weld w i t h s a l t

or bismuth a t t h e time t h e s p e c i f i c g r a v i t y pot w a s i n s t a l l e d .

11. REFERENCES

1. L. E , McNeese, "Rare Earth Removal Using t h e Metal Transfer P r o c e s s , 1 1 Engineering Development Studies for Molten-Salt -Breeder Reacio:r Processing No. 5, ORNL-TM-3140 (in press). 2. M. J. Bell and L, E. McNeese, Engineesi-ngDewlopment Studies for Molten-Salt -. Breeder Reactor Processing No. 1, ORNL-TM-3053 , pp.

38-48.

3. 1,. M. Ferris, MSR Program Semiann. Psagr. Rept. Feb. 28, 1970, O R N L - ~ I pp. ~ ~ ~289-92. ,

4. A. A. Jeje and. C. R. Bozzuto, Axial. Mixing (11), MIT-CEPS-X-102 (1970). -

in Open Bubble Columns

5. M. S. Bautista and L. E. McNeese, Engi-neeringDevelopment Studies for Molten-Salt Breeder Reactor Processing No, 4 , ORNL-TM-3139, pp. 38-83.

6. A.

M. Shei.kh and J. D. Dearth, Axial Mixing; in Open Bubble Columns, Mm-cEPS-x-gi (1969).

7. J.

S . Watson and L. E. McNeese, "Axial Mixing in Open Bu'o'oLe Columns," Hngiiieering Development S t u d i e s for Molten-Salt Breeder Reactor Processing No. 5 , ORNL-TM-.3140 ( in publicaTion)

8. R. M. Davies and G. I. Taylor, Proc. Roy. Soc. (London), Ser. A 200, 375 (1950).

9. I;. E. McNeese and M. E.

Whatley, Engineering Development Studies f o r Molten-Salt breeder Reactor Processing No. 2' ORNL-TM-3137, pp. 22-)43. .-.

10. MSR Program Semiann. Progr. Iiept. Feb. 2 9 , 1368, 0RML-)-1.254, pp. 260-63. 11. 9, F. Bairnan, personal comnimication, August 1.970.

12. L. E. McNeese, "Protactinium lsolation Using FLuorina'r,ion--Reductive Extraction," Engineering Development Studies foy_Mol ten-Salt ~reeder Reactor Processing No. 5, ORNL-TM-z-jiO (in press). \

13.'

E. L. Youngbl-ood,R. P. Milford, R.

I;. Nicol, and J. B. Ruch, Corrosion of the Volatility Pilot Plant INOR-8Hydrofluorinator and Nickel 201 Fluorinator During Forty-he1 Processing Runs w i t h Zirconium-Uranium Alloy, ORNL-3623 (March 1965).

'lp,, J. C. Mailen, "Volatilization of Uranium as the Hexafluoride from ,/ Drops of Molten Fluoride Salt paper presented at the American - Chemical Society National Mccting, Chicago, Sept. 2, 1964.

/ l?., G. \,

I. C a t h e r s , M. R. Bennett, and R. L. J o l l e y , The Fused S a l t V o l - a t i l i t y P r o c e s s f o r Recovering Uranium, ORNL-2661 (1959).

Fluoride

16. M.

17.

1,h.t

E. Whatley e t al., U n i t Operations S e c t i o n Monthly P r o g r e s s b e p o r t , September 1963, ORNL-TM-785 (1964). 1 I

bhem. Technol, Div. Ann. P r o g ~ r . Rept. May 31, 1965, ORNL-3830, pp.

71-75

._/ R. P , M i l f o r d , S . Msnn, J . B. Ruch, and W. H. Carr, J r . , "Recovering (\ 18. Uranium Submarine Reactor F u e l s , " I n d . Eng. Chem. 53, 357 (196.1-). I'.

1 '

I _

/._

(19. MSR Program Semiann. P r o g r . Rept. Aug. 31, 1968,,ORNL-4344, _,

20.

Chem. Technol. Div. Ann. P r o g r . Rept. May 31, 1967, ORNL-4145,

95-97.

. Rept . Aug.

31 , 1968, ORNL-4344

4-11.

pp.

, pp.

21.

MSR Program Semiann Progr

22.

N . R . S t a n s e l , I n d u c t i o n Heating, M c G r a w - H i l l ,

23.

P. G. Simpson, I n d u c t i o n Heating, C o i l , and System Design, McGrawH i l l , New York, 1960.

New York,

302-5,

1949.

24. N. R . S t a n s e l , I n d u c t i o n Heating, McGraw-Hill, N e w York, 1-949,p . 31. 25 *

1 . G. Simpson, I n d u c t i o n Heating, C o i l , and System Design, McGrawH i l l , p. 141.

26.

J . R. Hightower, J r . , and L. E , McNeese, "MSRE D i s t i l l a t i o n Zxperiment," E n g i n e e r i n g Development S t u d i e s f o r Molten-Salt Breeder Reactor P r o c e s s i n g No. 5 , ORNL-TM-31.h'I ( i n press).

J . R . Iiightower, Jr., and L. E . McNeese, Low-Pressure D i s t i l l a t i o n of Molten F l u o r i d e Mixtures: Nonradioactive T e s t s f o r t h e MSRE DrEst i l l a t i o n Experiment, ORNL-4344 ( J a n u a r y 1 9 7 1 ) .

_ I _

S. S. K i r s l i s and F. F. Blankenship, MSR Program Semiann. P r o g r .

Rept. Feb. 29, 1968, OKNL-4254, p . 100.

29.

S. S. K i r s l i s and F. F. Blankenship, MSR Frogram Semiann, Progr. Rept. Feb. 28, 1969, ORNL-4396, pp. 145-53.

30.

M. S . Li.n and L . E. McNeese, Engineeriqq Development S t u d i e s f o r Molten-Salt Breeder Reactor P r o c e s s i n g No 2 , ORNL-TM-3137, pp. 82-89.

J . H. S h a f f e r , MSR Program Semiann. P r o g r . , R e p t . J u l y 31, 1964, ORNL3708, pp. 288-303. ', \

r i

{

32.

;

G. E. Brown and N. A. Bhagat, A PreliaALinai*y Conceptual Design of a P i l o t P l a n t f o r t h e P r o d u c t i o n of P u r i f i e d Fused Fluoride M i x t u r e s , ORNL-MIT-25 (May 30, 1967).

33.

D, A. J o n e s and J . A. A l v a r e z , Reduction of I r o n F l u o r i d e w i t h Hy-drogen i n Mixtures of Molten Salts in a Packed C a l m ( P_. a9- r t 1) ORNL-MIT-53 (May 6 , 1968)

34.

J. A. Alvarez and W.. H. P i t c h e r , J r . , Reduction of I r a n F l u o r i d e w i t h Hydrogen i n Mixtures of MolLen Salts i n a Packed Column ( P a r t IT), ORNL-MIT-56 (May 29, 1968).

35.

W. S . Pappas, "Continuous Moisture Analyzer f o r Gases Containing

36.

0. H. Howard and C . W. Weber, "An Improved Continuous I n t e r n a l E l e c t r o l y s i s Analyzer f o r G a s e o u s F l u o r i d e s i n I n d u s t r i a l Environm e n t s , " Am. I n d . Hya. Assoc. J . 23, 48-57 (1962).

37.

B. A. Hannaford, II. D. Cochran, L. E. McNeese, and C. W , Kee, Engineering Development Studi-es f o r Molten-Salt B r e e d e--r Reactor P r o c e s s i n g No. 3 , ORNL-TM-3138, pp. 30-39.

38.

J. S. Watson and L. E. McNeese, "Hyd.rodynamics of Packed Columii Ope r a t i o n w i t h High Density Fluids , ' I Engineering Development Studies

Hydrogen F l u o r i d e s

Anal. Ch e m .38 , 615

(1966).

f o r Molten-Salt Breeder Reactor P r o c e s s i n g No. 5 , ORNL-TM-31-40 press).

(in

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