Ornl tm 3257 by The "E" Generation

OAK RIDGE NATIONAL LABORATORY LIBRARIES

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‘UNIG

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RATo RY

N U C L E A R DIVISION

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U . S . A T O M I C E N E R G Y COMMISSION

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ORNL- TM- 325Z?

S sn DIES FORMOLTE,.-SA ,T ENGI \ I E E R I ~DEVELOPMENT BREEDER REACTOR PROCESSING NO. 7 L. E. McNeese

NOTICE T h i s document c o n ta i n s i n fo r m a ti o n o f a p r e l i m i n a r y nature and was prepared p r i m a r i l y for i n te r n a l u s e a t th e Oak R i d g e N a t i o n a l Labor at or y. I t i s s u b j e c t to r e v i s i o n or c o r r e c ti o n and therefore does n o t represent a f i n a l report.

3 ./,(

ORNL-TM-3257

Contract No W-7405-eng-26 ENGINEERING DEVELOPMENT STUDIES FOR MOLTEN-SALT BREEDER REACTOR PROCESSING NO. 7 L a E. McNeese

FEBRUARY 1972

OAK RIDGE NATIONAL LABORATORY O a k Ridge, Tennessee 37830 operated by UNION CARBIDE CORPORATION f o r the U.S. ATOMIC ENERGY COMMISSION

Reports previously issued in this series are as follows: Period ending July 1968

0~~-4365 OWL- 4366

Period ending September 1968

ORNL-TM-3053

Period ending December 1968

ORNL-TM-3137

Period ending March 1969

OWL-TM-3138

Period ending June 1969

ORNL-TM-3139

Period ending September 1969

OWL-TM-3140

Period ending December 1969

ORNL-TM-3141

Period ending March 1970

'tr

iii

CONTENTS Page V

1. INTRODUCTION

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

2. ANALYSIS OF THE FLUORINATION--REDUCTIVE EXTRACTION AND METAL TRANSFER FLOWSKEET

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

2.1 Distribution of Rare-Earth and Alkaline-Earth Elements Between Molten Salt and Bismuth Containing Reductant

2,2 Isolation of Protactinium Using Fluorination--Reductive Extraction .

. ..

2.3

2.4 3.

. .. . . . Removal of Noble Metals with the Fluorination--Reductive Extraction Flowsheet .. ... ...... Halogen Removal in the Uranium Removal System . ... e

DEVELOPMENT OF A FROZEN-WALL FLUORINATOR: DESIGN CALCULATIONS FOR INDUCTION HEATING OF A FROZEN-WALL FLUORINATOR

3.1 Effects of Wall Temperature, Current, Frequency, and Fluorinator Diameter on the Thickness of the Frozen Film 16 3.2 Control of Frozen Film Thickness, and Approximate Dynamics ofFreezing. . 23 3.3 Power Requirements for an Experimental Fluorinator 26

...

..... .

. DEVELOPMENT OF THE METAL TRANSFER PROCESS . . . ... 4.1 Equipment and Materials Used for Experiment MTE-1 . . . 4.2 Experimental Procedure .. . .. 4.3 Experimental Results . . . .. 4.4 Postoperational Equipment Examination . . . . . . . . . e

4.5 Design and Testing of Bismuth Check Valves

a Carbon-Steel Pump Having Molten-

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

5. STUDY OF THE PURIFICATION OF

29 33 35 45

...... .

SALT BY CONTINUOUS METHODS

5.1 Batch Treatment of Salt for Oxide Removal

5.2 Measured Flooding Rates During Countercurrent Plow of Molten Salt and Hydrogen or Argon . 49

. ......... .... *,

6. SEMICONTINUOUS REDUCTIVE EXTRACTION EXPERIMENTS IN,A MILD-STEEL FACILITY..

. . . . * . .. . . . . . . . . . . . . . . . . . .

CONTENTS (Continued) Page

6.1 Preparation for Mass Transfer Experiments 6.2 Mass Transfer Experiment UTR-1 . 6.3

Mass Transfer Experiment UTR-2

...

... . .

52 53

MEASUREMENT OF AXIAL DISPERSION COEFFICIENTS IN PACKED COLUMNS

7.1

Experimental Results

. .. ..

T 0 2 Comparison of Results with a Published Correlation

8. REFERENCES..

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

60 88 90

SUMMARIES ANALYSIS OF THE FLUORINATION--REDUCTIVE EXTRACTION AND ZTAL TPAJEFER FLOWSHEET Recently obtained data on the distribution of several rare earths between molten salt and bismuth containing reductant have been use(? in additional calculations made to identify the important operating para-meters in the flowsheet and to determine the optimum operating conditions.

The behavior of fission products more noble than uranium in the

fluorination--reductive extraction process has also been considered, and the effects of these materials on the reactor breeding ratio have been calculated.

Calculations were also carried out to determine the heat

generation rates associated with the decay of halogen fission products that will be removed by fluorination. DEVELOPMENT OF A FROZEN-WALL FLUORINATOR: DESIGN CALCULATIONS FOR INDUCTION HEATING OF A FROZEN-WALL FLUORINATOR Calculations were made to show the effects of coil. current, frequency, wall temperature, and fluorinator diameter on the thickness of the frozen salt film in a continuous fluorinator that employs high-frequency induction heating. An approximate analysis of the dynamics of frozen film formation was carried out, and methods for controlling the frozen film thickness were examined. Calculations were also carried out to estimate the power requirements for a 5-ft-long experimental fluorinator that employs rf heating. DEVELOPMENT OF THE METAL TRANSFER PROCESS The f i r s t engineering experiment (MTE-1) for studying the removal of rare earths from single-fluid MSBR fuel salt by the metal transfer process was completed during this reporting period.

The main objective

of the experiment was to demonstrate the selective removal of rare earths (La and Nd) from a fluoride salt mixture containing thorium fluoride. The experiment was performed at 660째c in a 6-in.-diam carbon-steel vessel,

which c o n t a i n e d two compartments i n t e r c o n n e c t e d a t t h e bottom by a p o o l of molten bismuth t h a t was s a t u r a t e d w i t h thorium.

One compartment con-

t a i n e d f l u o r i d e s a l t t o which 2 m C i o f 147Nd and a s u f f i c i e n t q u a n t i t y of t o produce a c o n c e n t r a t i o n of 0.38 mole 3 second compartment c o n t a i n e d L i C 1 .

LaF

had been added.

The

The 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 t h e rare e a r t h s between t h e f l u o r i d e s a l t and t h e thorium-saturated bismuth were r e l a t i v e l y c o n s t a n t throughout t h e r u n and were i n agreement w i t h expected v a l u e s .

The 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 t h e r a r e e a r t h s between t h e L i C l and t h e thoriums a t u r a t e d bismuth were h i g h e r t h a n a n t i c i p a t e d d u r i n g t h e f i r s t p a r t o f t h e r u n b u t approached t h e expected v a l u e s n e a r t h e end o f t h e r u n . Approximately 50% o f t h e lanthanum and 25% of t h e neodymium o r i g i n a l l y p r e s e n t i n t h e f l u o r i d e s a l t were removed d u r i n g t h e r u n .

The rates a t which t h e r a r e e a r t h s were removed a r e i n c l o s e agreement w i t h expected r e moval r a t e s ; however, t h e r a r e e a r t h s d i d not c o l l e c t i n t h e lithium-bismuth s o l u t i o n ( w i t h which t h e L i C l was c o n t a c t e d ) as expected. t h e r a r e e a r t h s were found i n a 1 / 8 - i n . - t h i c k

I n s t e a d , most of l a y e r o f material l o c a t e d a t

t h e i n t e r f a c e between t h e L i C l and t h e t h o r i u m - s a t u r a t e d bismuth.

It i s b e l i e v e d t h a t t h e p r e s e n c e of oxide i n t h e system may account f o r t h e ac-

cumulation of t h e r a r e e a r t h s a t t h i s p o i n t .

STUDY OF THE PURIFICATION OF SALT BY CONTINUOUS mTHODS

The system w a s charged w i t h 28 kg o f s a l t (66-34 mole

% LiF-BeF2),

and t e n f l o o d i n g runs were c a r r i e d out u s i n g hydrogen and argon. During t h e s e r u n s , s a l t flow r a t e s of 50 t o 400 cm3/min were used w i t h argon and hydrogen flow rates of up t o 7.5 and 30 l i t e r s / m i n , r e s p e c t i v e l y . The temperature o f t h e column was 700째C i n each c a s e .

The p r e s s u r e drop a c r o s s t h e column i n c r e a s e d l i n e a r l y w i t h i n c r e a s e d g a s flow r a t e ; however,

t h e s a l t flow r a t e had o n l y a minor e f f e c t on p r e s s u r e drop. flow r a t e p o s s i b l e w i t h t h e p r e s e n t system i s about

The maximum

19% o f t h e c a l c u l a t e d

f l o o d i n g rate. w c

v ii

SEMICONTINUOUS REDUCTIVE EXTRACTION EXPERIMENTS I N A MILD-STEEL FACILITY U

Following r o u t i n e H -HF t r e a t m e n t o f t h e bismuth and t h e s a l t i n 2 t h e system, t h e phases were t r a n s f e r r e d t o t h e r e s p e c t i v e f e e d t a n k s . Then 90 g of p u r i f i e d LiF-UF4 e u t e c t i c s a l t w a s added t o t h e s a l t phase t o produce a UF4 c o n c e n t r a t i o n of about 0.0003 mole f r a c t i o n f o r t h e f i r s t mass t r a n s f e r r u n (UTR-1)

Hydrodynamic performance d u r i n g t h e

140-min run w a s e x c e l l e n t , and t e n p a i r s of bismuth and s a l t samples were t a k e n .

The column was o p e r a t e d at 62% and 76% of f l o o d i n g ( a t a

bismuth-to-salt

volumetric flow r a t e r a t i o of u n i t y ) ; n e v e r t h e l e s s , v i r -

t u a l l y none of t h e uranium was e x t r a c t e d from t h e s a l t due t o an opera t i o n a l d i f f i c u l t y t h a t prevented r e d u c t a n t from b e i n g added t o t h e b i s muth. D i s s o l u t i o n of thorium i n t h e bismuth f e e d t a n k i n p r e p a r a t i o n f o r t h e second mass t r a n s f e r experiment proceeded slowly as t h e r e s u l t of I

poor mixing i n t h e t a n k . from t h e s a l t .

I n r u n UTR-2, 95% of t h e uranium was e x t r a c t e d

The r u n w a s made w i t h a 200% excess o f r e d u c t a n t over

t h e s t o i c h i o m e t r i c requirement and w i t h bismuth and s a l t flow r a t e s of 247 ml/min and 52 ml/min, r e s p e c t i v e l y . t o about 77% o f f l o o d i n g .

These flow r a t e s a r e e q u i v a l e n t

T h i s experiment r e p r e s e n t s t h e f i r s t known

demonstration of t h e continuous e x t r a c t i o n of uranium from molten s a l t i n t o bismuth c o n t a i n i n g r e d u c t a n t .

The r e s u l t s i n d i c a t e t h a t h i g h

uranium removal e f f i c i e n c i e s can b e o b t a i n e d i n a packed column having a reasonable length.

MEASUREMENT

OF AXIAL DISPERSION COEFFICIENTS I N PACKED COLUMNS

We have continued our measurements of a x i a l d i s p e r s i o n i n packed c o l umns 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 f l u i d s having h i g h d e n s i t i e s and a high d e n s i t y d i f f e r e n c e . H

These experiments (which u s e mercury and w a t e r )

were i n t e n d e d t o s i m u l a t e t h e c o n d i t i o n s i n packed columns through which bismuth and molten s a l t a r e i n c o u n t e r c u r r e n t flow.

Results reported

viii

p r e v i o u s l y f o r a 2-in.-ID

column packed w i t h 3/8-in.

Raschig r i n g s a r e

compared w i t h d a t a o b t a i n e d d u r i n g t h i s r e p o r t i n g p e r i o d f o r l / b - i n . Raschig r i n g s , 1 / b - i n .

s o l i d c y l i n d e r s , and 1 / 2 - i n .

Raschig r i n g s .

each c a s e , 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 was independent of t h e d i s persed-phase (mercury) flow r a t e . 1/2-in.

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 3/8- and

packing were a l s o independent o f t h e continuous-phase ( w a t e r ) 2

flow r a t e ; t h e i r v a l u e s were 3.5 and 4.8 cm / s e e , r e s p e c t i v e l y . f o r t h e 1/b-in.

Data

packing i n d i c a t e t h a t t h e d i s p e r s i o n c o e f f i c i e n t i s i n -

v e r s e l y p r o p o r t i o n a l t o t h e continuous-phase flow r a t e .

The d a t a ob-

t a i n e d d u r i n g t h i s s t u d y a r e compared w i t h a p u b l i s h e d c o r r e l a t i o n o f

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

The p r e s e n t d a t a are found t o b e

i n good agreement w i t h t h e p u b l i s h e d c o r r e l a t i o n ; t h i s i s remarkable s i n c e t h e c o r r e l a t i o n was developed from d a t a o b t a i n e d w i t h systems having d e n s i t y d i f f e r e n c e s between one and two o r d e r s of' magnitude l e ss t h a n t h e d e n s i t y d i f f e r e n c e of t h e mercury-water

system.

. d'

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 (MSBR) w i l l be f u e l e d w i t h a molten

f l u o r i d e mixture t h a t w i l l c i r c u l a t e through t h e b l a n k e t and c o r e r e g i o n s of t h e r e a c t o r and through t h e primary h e a t exchangers.

We a r e developi n g p r o c e s s i n g methods f o r use i n a close-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 o r i d e m i x t u r e . S e v e r a l o p e r a t i o n s a s s o c i a t e d w i t h MSBR 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 of t h i s r e p o r t d e s c r i b e :

(1)optimized c o n d i t i o n s

f o r o p e r a t i o n w i t h t h e combined flowsheet t h a t u t i l i z e s b o t h 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 m e t a l t r a n s f e r p r o c e s s , and r e s u l t s of calcul a t i o n s showing t h e e f f e c t of noble-metal removal t i m e on r e a c t o r b r e e d i n g performance and t h e h e a t g e n e r a t i o n r a t e s a s s o c i a t e d w i t h decay of t h e halogen f i s s i o n p r o d u c t s ; ( 2 ) r e s u l t s o f c a l c u l a t i o n s t h a t show t h e sens

s i t i v i t y of t h e f r o z e n f i l m t h i c k n e s s i n a continuous f l u o r i n a t o r h e a t e d by high-frequency i n d u c t i o n h e a t i n g t o c o i l c u r r e n t , frequency, w a l l tempe r a t u r e , and f l u o r i n a t o r d i a m e t e r ; ( 3 ) r e s u l t s of t h e f i r s t e n g i n e e r i n g experiment f o r demonstrating 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 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 from f l u o r i d e s a l t m i x t u r e s ;

( 4 ) s t u d i e s of

t h e continuous p u r i f i c a t i o n of s a l t ; ( 5 ) experiments made 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 demonstrate t h e e x t r a c t i o n of uranium from molten 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 bismuth c o n t a i n i n g reduct a n t ; and

( 6 ) measurements of a x i a l d i s p e r s i o n i n packed 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 mercury and w a t e r .

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 A p r i l through June

1970

ANALYSIS OF THE FLUORINATION--REDUCTIVE AND METAL TRANSFER FLOWSHEET M. J . B e l l

EXTRACTION

L. E . McNeese

A flowsheet t h a t u s e s 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

m e t a l t r a n s f e r p r o c e s s f o r removing p r o t a c t i n i u m and t h e rare e a r t h s from t h e f u e l s a l t of a s i n g l e - f l u i d MSBR h a s been d e s c r i b e d p r e v i o u s l y .

C a l c u l a t i o n s t o i d e n t i f ' y t h e important o p e r a t i n g parameters i n t h i s flows h e e t and t o determine t h e optimum o p e r a t i n g c o n d i t i o n s have been c o n t i n u e d u s i n g r e c e n t l y o b t a i n e d d a t a on t h e d i s t r i b u t i o n o f s e v e r a l rare e a r t h s between molten s a l t and bismuth c o n t a i n i n g r e d u c t a n t .

The b e h a v i o r of

f i s s i o n p r o d u c t s more noble t h a n uranium i n 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 h a s a l s o been c o n s i d e r e d , and t h e e f f e c t s o f t h e s e m a t e r i a l s on t h e r e a c t o r b r e e d i n g r a t i o have been determined by means o f calculations.

C a l c u l a t i o n s were a l s o c a r r i e d o u t t o determine t h e h e a t

g e n e r a t i o n r a t e s a s s o c i a t e d w i t h t h e decay o f halogen f i s s i o n p r o d u c t s t h a t w i l l b e removed by f l u o r i n a t i o n .

These items a r e d i s c u s s e d i n d e t a i l

i n t h e remainder o f t h i s s e c t i o n .

2.1

D i s t r i b u t i o n of Rare-Earth and Alkaline-Earth Elements Between Molten S a l t and Bismuth Containing Reductant F e r r i s and co-workers2 have continued t o measure t h e e q u i l i b r i u m

d i s t r i b u t i o n o f f i s s i o n product and a c t i n i d e elements between molten s a l t and bismuth c o n t a i n i n g r e d u c t a n t .

They have found t h a t , a t a g i v e n

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 f o r element M, d e f i n e d as

-- mole f r a c t i o n o f

M i n bismuth phase mole f r a c t i o n of M i n s a l t phase '

can be expressed as

l o g DM = n l o g XLi + log

+â&#x201A;Ź

3 where = the mole fraction of lithium in the bismuth phase,

'Li

n = the valence of M in the salt phase, and log KM = a constant. +$

Plots of the log K&

values vs reciprocal absolute temperature are linear

over the temperature range 625-750'~~as shown in Fig. 1. Thus, the temp-

erature dependence of log can be expressed as log % = A + B/T. Values of the constants A and B used in the present flowsheet calculation are +$

shown in Table 1 for several elements. These data indicate that the distribution of the rare earths is relatively insensitive to temperature and that the distribution coefficients for a given element are about the same, regardless of whether lithium chloride or lithium bromide is used as the salt phase. 2.2 Isolation of Protactinium Using Fluorination--Reductive Extraction e

Calculations were made for selecting optimum operating conditions for the protactinium isolation system. Optimum conditions were tentatively assumed to be those resulting in the minimum partial fuel cycle cost. The partial fuel cycle cost includes the following components of the fuel cycle cost which are associated with the isolation of protactinium:

(1)bismuth and uranium inventories in the protactinium decay tank, (2) the loss of bred uranium resulting from inefficient protactinium isolation, (3) the cost of 7Li reductant required to extract uranium and protactinium from the fuel salt, and

(4) the cost of BeF2 and ThF4, which must be added to

the system in order to maintain a constant fuel salt composition. An interest rate of 14% per annum was used to compute inventory charges, and -

the value of 233U was taken to be $12/g. The following costs were used for chemicals : bismuth, $5/lb; ThF4 , $6.50/lb; BeF2 , $7.50/lb; and 7Li metal , $55/lb. Values that were obtained for the partial fuel cycle cost include m

only those charges directly related to the isolation of protactinium and include no contribution either for fluorination of the fuel salt to remove

750 I

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6 uranium o r f o r removal of f i s s i o n p r o d u c t s ( n o t a b l y zirconium) i n t h e p r o t a c t i n i u m i s o l a t i o n system. The e f f e c t o f t h e number of e q u i l i b r i u m s t a g e s i n t h e e x t r a c t i o n calumns above and below t h e p r o t a c t i n i u m decay t a n k on t h e p a r t i a l f u e l c y c l e c o s t i s shown i n F i g . 2.

I n t h e f i n a l s e l e c t i o n o f t h e number of

s t a g e s f o r t h e s e columns, one must c o n s i d e r t h e expense a s s o c i a t e d w i t h an i n c r e a s e d number o f s t a g e s .

The d e c i s i o n t o u s e two s t a g e s below

and f i v e s t a g e s above t h e p r o t a c t i n i u m decay t a n k was made because a l a r g e r number of s t a g e s r e s u l t s i n only a small d e c r e a s e i n c o s t .

For

a r e d u c t a n t f e e d r a t e of 429 equiv/day and a thorium c o n c e n t r a t i o n i n t h e bismuth e n t e r i n g t h e column e q u a l t o 90% o f t h e thorium s o l u b i l i t y

a t 640째C, t h e bismuth-to-salt

i s 0.14.

volumetric flow r a t e r a t i o i n t h e columns

The r e q u i r e d column diameter i s 3 i n . i f t h e column i s packed

w i t h 3/8-in.

molybdenum Raschig r i n g s .

The e f f e c t s o f changes i n t h e r e d u c t a n t a d d i t i o n r a t e and i n t h e volume o f t h e p r o t a c t i n i u m decay t a n k on t h e p a r t i a l f u e l c y c l e c o s t are shown i n F i g . 3.

The c a p i t a l c o s t o f t h e decay t a n k , a r e l a t i v e l y

expensive equipment i t e m , w i l l a l s o i n f l u e n c e t h e f i n a l c h o i c e s f o r t h e t a n k volume and t h e r e d u c t a n t f e e d r a t e ; however, t h i s c o s t has not y e t '1

been t a k e n i n t o c o n s i d e r a t i o n .

Values o f 161 f t 3 f o r t h e decay t a n k

volume and 429 e q u i v of r e d u c t a n t p e r day were s e l e c t e d as optimum.

De-

c r e a s i n g t h e r e d u c t a n t f e e d r a t e from 429 e q u i v / d a y t o 400 equiv/day r e duces t h e p a r t i a l f u e l c y c l e c o s t by 2% and i n c r e a s e s t h e i n v e n t o r y charge on bismuth i n t h e decay t a n k by about 5%.

The e f f e c t o f t h e o p e r a t i n g

temperature on t h e performance o f t h e p r o t a c t i n i u m i s o l a t i o n system, as shown by changes i n t h e p a r t i a l f u e l c y c l e c o s t , i s g i v e n i n F i g . 4. A minimum p a r t i a l f u e l c y c l e c o s t of 0.0453 mill/kWhr i s observed f o r t h e following conditions:

a temperature o f 640째C, a column having two s t a g e s

below and f i v e s t a g e s above t h e p r o t a c t i n i u m decay t a n k , a decay t a n k volume o f

1 6 1 f t 3 , and a r e d u c t a n t a d d i t i o n r a t e o f 429 equiv/day.

These c o n d i t i o n s , which have been chosen as 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 ,

r e s u l t i n a p r o t a c t i n i u m removal t i m e o f 10.7 days and a uranium i n v e n t o r y of 1 2 . 7 kg (about

0.67% of

the reactor inventory) i n t h e protactinium

ORNL DWG 70-10,990

0.052

REDUCTANT ADDITION RATE =429EQUIVALENTS/I 90% OF T h SOLUBILITY IN Bi TEMPERATURE = 64OoC Pa DECAY TANK VOLUME=161 FT3 Pa PROCESSING CYCLE = 10 DAYS

0.050 h

Y \

*E 0.048 U

Iv)

0 0

STAGES IN LOWER COLUMh

0.046 0

0 1

0.044 1

5 I-

0.042

STAGES IN UPPER COLUMN

Fig. 2. Partial Fuel Cycle Cost for the Protactinium Isolation System as a Function of the Number of Stages in the Extractors Above and Below the Protactinium Decay T a n k .

ORNL DWG 70-10,991

0.052

' J

STAGES I LOWER COLUMN

L i FEED RATE (MOLES/DAY)

0.050 n L

1: -

0.048

0.046

0 -I

0.044 -J

Q I-

0.042

STAGES IN UPPER COLUMN =5 TEMPERATURE =64OoC Th CONC IN Bi =9OayO OF Th SOLUBILITY AT 640% Pa PROCESSING CYCLE=10 DAYS

140

1 160

I 180

200

Pa DECAY TANK VOLUME ( f t 3 )

Fig. 3. Partial Fuel Cycle Cost for the Protactinium Isolation System as a Function of the Protactinium Decay Tank Volume and the Reductant Addition Rate.

ORNL DWG 70-10,992 0.050

STAGES IN UPPER COLUMN=5 STAGES IN LOWER COLUMN = 2 REDUCTANT ADDITION RATE = 429 MOLESA DECAY TANK VOLUME=161 f t 3 Pa PROCESSING CYCLE =10 DAYS

0.049

0.048

I-

0.047

12 w

r I-

0 W -I

0 > 0 -I W

-I

zir W

0.046

3 LL

0.045

0.044

I 620

I 630

640

1 650

660

TEMPERATURE ( " C )

Fig. 4. Protactinium Removal Time and Partial Fuel Cycle Cost for Protactinium Isolation System as a Function of Temperature.

decay t a n k .

The components of t h e p a r t i a l f u e l c y c l e c o s t are as f o l l o w s :

bismuth i n v e n t o r y c h a r g e , 0.0097 mill/kWhr; uranium i n v e n t o r y c h a r g e , 0.003 mill/kWhr; l o s s i n 233U

due t o i n e f f i c i e n t p r o t a c t i n i u m i s o l a t i o n ,

0.0013 mill/kWhr; 7 L i m e t a l consumption, 0.0151 mill/kWhr; and BeF2 and

ThF

a d d i t i o n , 0.0163 mill/kWhr.

2.3

Removal o f Noble Metals w i t h t h e F l u o r i n a t i o n - Reductive E x t r a c t i o n Flowsheet

Previous c a l c u l a t i o n s of f i s s i o n product i n v e n t o r i e s and p o i s o n i n g i n an MSBR have assumed t h a t most of t h e noble m e t a l s ( S e , Nb, Mo, Tc, Ru, Rh, Pd, Ag, Sb, and Te) have been removed f r o m t h e f u e l s a l t on a s h o r t (50-sec) c y c l e by b e i n g p l a t e d o u t on m e t a l s u r f a c e s o r by b e i n g t r a n s p o r t e d t o t h e off-gas system as a flsmoke.f' A s a r e s u l t o f t h e s e assumptions, t h e n e u t r o n poisoning by t h e s e m a t e r i a l s was n e g l i g i b l e ; howe v e r , t h e h e a t l o a d on t h e off-gas system w a s i n c r e a s e d by about 1 0 Mw. A more c o n s e r v a t i v e assumption w i t h r e g a r d t o b o t h neutron p o i s o n i n g and

h e a t g e n e r a t i o n i n t h e p r o c e s s i n g p l a n t would be t h a t a s i g n i f i c a n t f r a c t i o n of t h e s e m a t e r i a l s w i l l remain i n t h e f u e l s a l t and w i l l b e removed i n t h e p r o c e s s i n g p l a n t .

Accordingly, we have made c a l c u l a t i o n s

t o e s t i m a t e t h e n e u t r o n poisoning caused by t h e s e m a t e r i a l s i n t h e event t h a t t h e y remain i n t h e f u e l s a l t .

These c a l c u l a t i o n s assumed a chemical

p r o c e s s i n g system i n which p r o t a c t i n i u m was removed 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 on a 10-day c y c l e and t h e r a r e e a r t h s were removed on a 25-day c y c l e by t h e m e t a l t r a n s f e r p r o c e s s .

Many of t h e noble

m e t a l s ( i . e . , S e , Nb, Mo, Tc, Ru, Sb, and Te) 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 and can be s e p a r a t e d w i t h v a r y i n g d e g r e e s of d i f ficulty

from UF

6 by

s o r p t i o n on materials such as NaF.

The remaining

m a t e r i a l s ( G a , Ge, Rh, Pd, Ag, Cd, I n , and Sn) are r e l a t i v e l y s o l u b l e i n bismuth and w i l l b e e x t r a c t e d i n t o t h e bismuth w i t h t h e same removal time as Pa. I n t h e s e c a l c u l a t i o n s , t h e removal time of t h e i n d i v i d u a l noble-

metal elements w a s v a r i e d from 2.5 t o 640 d a y s , and t h e e f f e c t of t h i s v a r i a t i o n on t h e r e a c t o r performance w a s determined.

F i g u r e 5 shows t h e

0 0

In N

0 In 0 0

2 I

0 0

0 0 (u

e f f e c t o f t h e removal time f o r important noble m e t a l elements which form The elements t h a t have

v o l a t i l e f l u o r i d e s on t h e f u e l y i e l d of an M S B R .

t h e most e f f e c t on n e u t r o n poisoning a r e Tc, Ru, and M o ; S e , Sb, Nb, and Te have v i r t u a l l y no e f f e c t .

The c u r v e s i n F i g .

are relatively flat

f o r removal times s h o r t e r t h a n about 100 d a y s , i n d i c a t i n g t h a t t h e r e moval e f f i c i e n c y f o r a n i n d i v i d u a l element may be as l o w as 10% w i t h o u t s e r i o u s l y i m p a i r i n g r e a c t o r performance.

Figure

6 shows t h e e f f e c t of

removal time on t h e f u e l y i e l d f o r elements w i t h n o n v o l a t i l e f l u o r i d e s . Here, a r e l a t i v e l y l a r g e d e c r e a s e i n f u e l y i e l d i s a s s o c i a t e d w i t h l o n g removal t i m e s f o r Rh, w h i l e t h e elements Cd, Pd, and Ag have o n l y a small effect.

N e g l i g i b l e e f f e c t s were observed f o r G a , G e , I n , and Sn.

t h e s e c a l c u l a t i o n s , a 10-day removal t i m e for a l l noble metals was t a k e n as t h e r e f e r e n c e c o n d i t i o n .

For t h i s c o n d i t i o n , t h e t o t a l n e u t r o n poi-

soning ( Y ) f o r t h e noble m e t a l s i s 0.0010 a b s o r p t i o n p e r f i s s i l e absorpThe p r i n c i p a l i s o t o p e s c o n t r i b u t i n g t o t h i s p o i s o n i n g are:

tion.

Y = 0.00085; ' 1 3

lo5Rh ,

Cd, Y = 0.00005; 99Tc, Y = 0.00003; and lo3Rh, Y = 0.00002.

If t h e n o b l e metals a r e removed on a 10-day c y c l e , t h e i r combined

t h e r m a l power w i l l be 0.98 MW.

The h e a t l o a d on t h e f l u o r i n a t o r off-gas

system w i l l depend on t h e f r a c t i o n s o f noble-metal f l u o r i d e s t h a t a r e c o l l e c t e d i n t h i s system and t h e i r r e s i d e n c e t i m e .

The i m p o r t a n t h e a t

s o u r c e s among noble m e t a l s having v o l a t i l e f l u o r i d e s a r e g i v e n i n Table 2.

T h e maximum amount o f h e a t t h a t c o u l d b e produced i n t h e UF

6 separat i o n system, assuming t h a t t h e s e i s o t o p e s were c o l l e c t e d w i t h 100% eff i c i e n c y and r e t a i n e d i n d e f i n i t e l y would be 0.95 MW.

S i m i l a r d a t a are

shown i n Table 3 f o r t h e noble-metal f i s s i o n p r o d u c t s whose f l u o r i d e s are not v o l a t i l e .

These i s o t o p e s w i l l add a maximum o f 30 kW o f h e a t

t o t h e bismuth stream i n t h e p r o t a c t i n i u m i s o l a t i o n system.

2.4 Halogen Removal i n t h e Uranium Removal System I n t h e fluorination--reductive

e x t r a c t i o n flowsheet f o r removal o f

uranium and i s o l a t i o n o f p r o t a c t i n i u m from M S B R f u e l s a l t , t h e halogen f i s s i o n p r o d u c t s w i l l be removed as v o l a t i l e f l u o r i d e s and w i l l e n t e r t h e UF

s e p a r a t i o n system w i t h a 10-day removal t i m e .

These materials

0 RNL-DWG-71-9493

io2

E 3

c 0 L

a, Q

- 0.025

LI1 -1

-0.05C

-1 W

3 LL

-0.07:

c3 Z

- 0.1oc

200

400

REMOVAL TIME ( d a y s )

Fig. 6 . E f f e c t of Removal T i m e on Fuel Yield f o r Noble Metals That Do Not Form V o l a t i l e F l u o r i d e s .

io3

Table 2.

Thermal Power of I s o t o p e s o f Noble-Metal Elements That Have V o l a t i l e F l u o r i d e s Removal t i m e , 1 0 days Thermal Power

Isotope

(kW)

Half - L i f e

78 h 139

67 h

106

40 d

45.1

1.0 y

44.6

34 d

44.0

35 d

27.2

3.9 d

18.7

1.2 d

14.3

42 m

12.3

12.5 d

10.7

4.5 h

9.4

50 m

4.5

72 m

3.5

2.7 y

3.0

25 m

3.0

105 d

2.8

9.6 h

2.2

4.43 h

1.7

6.0 h

1.5

39 m

1.5

Table 3. Thermal Power of Isotopes of Noble-Metal Elements That Form Nonvolatile Fluorides Removal cycle, 10 days

Isotope

Thermal Power (kW)

Half-Life

126Sn

20.2

%lo 5 y

5-2

9.62 d

4.9

l h

2.4

62 m

127Sn

2.4

2.1 h

lo5Rh

1.8

36 h

111 Ag

0.56

7.5 d

0.48

21.0 h

0.47

2.3 d

0.18

13.5 h

0.14

2.2 h

0.09

43 d

125Sn

'13Ag

0.08

l17Cd

0.07

2.5 h

112 Ag

0.07

3.2 h

lo7Rh

0.03

21.7 m

16 w i l l c o n t a i n a number of i s o t o p e s which c o u l d c o n t r i b u t e as much as 0 . 3 MW t o t h e h e a t l o a d on t h e fluorinator--UF

c o l l e c t i o n system.

p r i n c i p a l h e a t sources i n t h i s group are g i v e n i n Table

The

With t h e ex-

c e p t i o n o f 13â&#x20AC;&#x2122;1, a l l of t h e important m a t e r i a l s a r e i s o t o p e s of i o d i n e w i t h h a l f - l i v e s of l e s s t h a n 1 day.

The maximum r a t e a t which i o d i n e

and bromine would be c o l l e c t e d i n t h e uranium removal system i s 1 g/day.

DEVELOPMENT OF A FROZEN-WALL FLUORINATOR: DESIGN CALCULATIONS FOR INDUCTION HEATING OF A FROZEN-WALL FLUORINATOR J . R , Hightower, J r .

C . P. Tung

We a r e c o n t i n u i n g t o s t u d y rf i n d u c t i o n h e a t i n g of molten s a l t as

a method f o r p r o v i d i n g a c o r r o s i o n - f r e e h e a t s o u r c e f o r an e x p e r i m e n t a l continuous f l u o r i n a t o r i n which a f i l m of s a l t i s f r o z e n on t h e walls t o protect against corrosion.

A p r e v i o u s study3 showed t h a t i n d u c t i o n

h e a t i n g may be s u i t a b l e f o r b a t c h f l u o r i n a t o r s , and we have made c a l c u t i o n s and experiments

4 which

i n d i c a t e t h a t i n d u c t i o n h e a t i n g can a l s o b e

used w i t h a continuous f l u o r i n a t o r . c

T h i s s e c t i o n summarizes r e s u l t s of c a l c u l a t i o n s t h a t show t h e eff e c t s o f c o i l c u r r e n t , frequency, w a l l t e m p e r a t u r e , and f l u o r i n a t o r diameter on 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 f i l m i n a continuous f l u o r i n a t o r employing high-frequency i n d u c t i o n h e a t i n g .

Methods f o r c o n t r o l -

l i n g t h e t h i c k n e s s of t h e f r o z e n f i l m a r e a l s o d i s c u s s e d .

S i n c e t h e ef-

f i c i e n c y o f h e a t i n g t h e s a l t cannot be r e l i a b l y c a l c u l a t e d , an experiment t h a t u s e s a n aqueous e l e c t r o l y t e as a s u b s t i t u t e f o r molten s a l t w i l l b e c a r r i e d o u t i n o r d e r t o measure h e a t i n g e f f i c i e n c y i n equipment similar t o the fluorinator.

3.1

E f f e c t s of Wall Temperature, C u r r e n t , Frequency, and F l u o r i n a t o r Diameter on t h e Thickness of t h e Frozen Film

I n t h e proposed f l u o r i n a t o r c o n f i g u r a t i o n ( d e s i g n a t e d p r e v i o u s l y 4 as c o n f i g u r a t i o n I ) , t h e i n d u c t i o n c o i l s are embedded i n t h e f r o z e n s a l t film

Table 4.

Isotope

Thermal Power of Isotopes of Halogens Removed on a 10-day Cycle Thermal Power (kW)

Half-Life

1 3 1

117 133,

134,

93.2

21 h

66.3

6.7 h

12.8

2.3 h

11.2

1.8

32 m

3Br

0.58

24 h

87Br

0.37

5.5

88Br

0.14

16 s

136,

0.12

83 s

5Br

0.11

3.0 m

86Br

0.10

82Br

0.06

35.7 h

0.06

24 s

0.06

6.3 s

89Br

0.04

4.5 s

130,

0.02

12.5 h

138,

â&#x20AC;?

8.05 d

18 near t h e fluorinator vessel w a l l .

I n t r e a t i n g t h e system m a t h e m a t i c a l l y ,

it was assumed t h a t t h e molten zone would behave as a s o l i d c y l i n d r i c a l charge i n an i n d u c t i o n c o i l and t h a t t h e e f f e c t of bubbles i n t h e molten s a l t would be n e g l i g i b l e . The h e a t g e n e r a t i o n r a t e i n an i n f i n i t e l y l o n g c y l i n d r i c a l charge p l a c e d i n s i d e an i n f i n i t e l y l o n g c o i l i s g i v e n by:

P =

where

-1

P = h e a t g e n e r a t e d i n molten s a l t , W*m

-1 -1 g = c o n d u c t i v i t y of molten s a l t , R * m , n = c o i l s p a c i n g , turns/m, I = rms c o i l current, A,

a = r a d i u s of molten s a l t zone, m, f = frequency, Hz,

1-1 = p e r m e a b i l i t y of s a l t , assumed t o be

10-7~*A-1.m--1,

b e r , b e r ' , b e i , and b e i ' a r e b e s s e l f u n c t i o n s .

A t s t e a d y s t a t e , t h e h e a t g e n e r a t e d i n t h e molten zone w i l l b e t r a n s -

f e r r e d by conduction through t h e f r o z e n f i l m t h a t surrounds t h e molten c o r e of t h e f l u o r i n a t o r .

The e q u a t i o n r e l a t i n g t h e r a t e o f h e a t flow t o t h e sys-

t e m dimensions and p r o p e r t i e s i s :

2~k(T.- T,)

where Q = h e a t t r a n s f e r r e d through t h e s a l t f i l m , W - m - l , 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 s a l t ,

W a r n

-1.oc-l 9

t = thickness of the frozen salt film between the molten zone and the inside of the induction coil, m, r = inside radius of the induction coil, m, 1 Ti = liquidus temperature of the salt, 'C,

Tc = temperature at the induction coil; here we assume that this temperature can be set when, actually, the fluorinator wall temperature is the quantity set. Combining Eqs. (1)and (2) results in an expression that defines the steady-state frozen film thickness in terms of system properties and the operating variables. Equation (1)contains bessel functions, and it is somewhat cumbersome to use; a more useful approximate equation, valid for alp < 1.4, is:

The salt phase, which is assumed to have the composition 68-20-12 mole % LiF-BeF2-ThF4, has the following properties: -1 -1 = 1.54 *cm at 480%' (ref. 51,

k = 0.0159 W*~rn-~*'C-lat 455'C

(ref. 6)*

It was assumed that the induction heating generator operated at 400 kHz. Combining Eqs. (2) and (3) and using the above values yields the following expression for the frozen film thickness:

where

Z1 = the inside diameter of the coil, in. (the equation is valid for D < 5 in.), 1t = the frozen film thickness, in., w

= Ti

Tc,

OC,

n = c o i l s p a c i n g , turns/m, I = r m s c o i l c u r r e n t , A. The e f f e c t of 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 f r o z e n f i l m f o r a range of c o i l c u r r e n t s was determined from Eq.

(b),

u s i n g a n assumed

c o i l s p a c i n g o f 78.7 t u r n s p e r meter ( 2 t u r n s / i n . ) a n d a 5-in.-ID

The r e s u l t s a r e shown i n F i g . 7 .

coil.

For a c o n s t a n t c o i l c u r r e n t , t h e steady-

s t a t e thickness of t h e frozen f i l m thickness increases with increasing 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 f i l m , as would b e expected.

The s e n s i -

t i v i t y o f t h e f i l m t h i c k n e s s t o changes i n t e m p e r a t u r e d i f f e r e n c e a l s o i n c r e a s e s as t h e t e m p e r a t u r e d i f f e r e n c e i n c r e a s e s .

F i n a l l y , t h e temp-

e r a t u r e d i f f e r e n c e can become so l a r g e t h a t a c o n d i t i o n i s reached i n which t h e h e a t g e n e r a t e d i n t h e molten zone i s not s u f f i c i e n t t o b a l a n c e t h e r a t e of h e a t l o s s from t h e system and t h e f l u o r i n a t o r w i l l f r e e z e completely.

The t h i c k n e s s of t h e f i l m at t h i s c r i t i c a l t e m p e r a t u r e d i f -

f e r e n c e i s dependent only on t h e diameter o f t h e f l u o r i n a t o r v e s s e l and t h e r e l a t i o n s h i p between t h e h e a t g e n e r a t e d p e r u n i t l e n g t h of f l u o r i n a t o r To i l l u s t r a t e t h i s , assume t h a t t h e

and t h e d i a m e t e r o f t h e molten zone.

h e a t g e n e r a t i o n r a t e i s g i v e n by t h e r e l a t i o n P = a(Dl

2t)b,

(5)

where

-1

P = h e a t g e n e r a t i o n r a t e , W-cm

a,b = c o n s t a n t s , and D

and t a r e as d e f i n e d f o r Eq.

(4).

If P i n Eq. ( 5 ) i s equated t o Q i n Eq. ( 2 ) ( r e w r i t t e n i n terms of d i a m e t e r

r a t h e r than r a d i u s ) , t h e following general equation i s obtained: /'

The c r i t i c a l f i l m t h i c k n e s s occurs when dt/dAT

-f

03,

or dAT/dt = 0 .

e x p r e s s i o n f o r t h e q u a n t i t y dAT/dt i s determined from Eq.

If an

( 1 6 ) and s e t

ORNL D W G 7 0 - 6 2 7 3

0.6 Maximum Stable Film Thickness

0.5

(I) (b

50 0.4 .s I-

.-E LL

0.3

s 2

0.2 Salt: 68-20-12 Moleo/o L i F - B t F z - T h F d Frequency: 400 k H z Coil Spacing: 78.7 Turns /Meter ( 2 TurnsIin.1 Inside D i a m e t e r o f Coil: 5 in.

0.I

0.5 L

40 45 50 A T Across S a l t Film, OC

Fig. 7. E f f e c t of Temperature D i f f e r e n c e Across Frozen Salt Film on t h e Film Thickness.

e q u a l t o z e r o and t h e n t h e r e s u l t i n g e q u a t i o n i s s o l v e d f o r t h e c r i t i c a l frozen f i l m t h i c k n e s s , t h e following r e l a t i o n r e s u l t s :

Dl ,

%it

where t

i s t h e maximum s t e a d y - s t a t e f i l m t h i c k n e s s t h a t can b e maincrit t a i n e d i n a f l u o r i n a t o r of diameter D

For an rf g e n e r a t o r o p e r a t i n g a t 400 kHz or l e s s , t h e exponent b i s 3.988 and t h e c r i t i c a l f i l m t h i c k n e s s i s g i v e n by:

tcrit

For a 5-in.-ID

= 0 . 1 1 1 D1.

c o i l , t h e c r i t i c a l film t h i c k n e s s i s 0.56 i n .

For a g e n e r a t o r o p e r a t i n g a t 1000 kHz, Eq. ( 3 ) would n o t be v a l i d ; however, t h e f o l l o w i n g e q u a t i o n would approximate t h e h e a t g e n e r a t i o n rate :

P = 2.387 x 10-4 n 2 I2 (D1 i n t h e range 3 i n . < (D1

2t) < 5 in.

2t)

3.146

(9)

The v a l u e o f b i s seen t o be

3.146, and t h e c r i t i c a l f i l m t h i c k n e s s i s given by:

t c r i t = 0.136 D1. Thus, a l a r g e r s t e a d y - s t a t e f i l m t h i c k n e s s can b e o b t a i n e d i n t h i s c a s e . The f o l l o w i n g equipment s i z e and c o i l s p a c i n g were chosen somewhat a r b i t r a r i l y and f o r convenience f o r f u r t h e r c a l c u l a t i o n s : which w i l l e a s i l y f i t i n s i d e a 6-in.

a 5-in. c o i l ,

sched 40 p i p e ; and a s p a c i n g o f 2 t u r n s

p e r i n c h , which i s e a s i l y o b t a i n a b l e w i t h 1/4- or 3/8-in.-diam

conductors.

A frequency of 400 kHz i s a s t a n d a r d o p e r a t i n g frequency f o r i n d u c t i o n

h e a t i n g g e n e r a t o r s and was used f o r t h i s r e a s o n .

The c a l c u l a t i o n s i n d i c a t e d t h a t t h e s e c h o i c e s a r e a c c e p t a b l e ; w i t h a c o i l c u r r e n t of 11 A , a

f r o z e n f i l m about 0.3 i n . t h i c k (which i s r e a s o n a b l y i n s e n s i t i v e t o vari a t i o n s i n temperature d i f f e r e n c e ) can b e maintained w i t h a t e m p e r a t u r e d i f f e r e n c e o f 51OC. and c o n t r o l l e d .

This t e m p e r a t u r e d i f f e r e n c e c o u l d be e a s i l y measured

Because o f t h e p r o p o r t i o n a l i t y between t h e maximum s t a b l e

f i l m t h i c k n e s s and t h e f l u o r i n a t o r d i a m e t e r , we probably would n o t use a

smaller-diameter v e s s e l f o r t h e e x p e r i m e n t a l f l u o r i n a t o r because t h e f r o z e n f i l m would have t o be i m p r a c t i c a l l y t h i n .

We would n o t use a l a r g e r diameter v e s s e l because t h e e f f e c t o f a x i a l d i s p e r s i o n would be s i g n i f i c a n t , and would r e s u l t i n a low uranium removal e f f i c i e n c y .

3.2

C o n t r o l o f Frozen Film Thickness, and Approximate Dynamics of F r e e z i n g

The e x i s t e n c e of a maximum, s t a b l e s t e a d y - s t a t e t h i c k n e s s of t h e f r o z e n f i l m s u g g e s t s t h a t c o n t r o l l i n g t h e t h i c k n e s s of t h e f i l m i n a f l u o r i n a t o r i n which t h e h e a t g e n e r a t i o n r a t e v a r i e s w i t h t h e diameter of t h e molten zone may be d i f f i c u l t .

The f o l l o w i n g c o n s i d e r a t i o n s of

t h e dynamics o f t h e f r e e z i n g p r o c e s s i n d i c a t e , however, t h a t t h i s i s n o t t h e case.

The a n a l y s i s i s n e c e s s a r i l y approximate s i n c e a more r e a l i s t i c

formulation r e s u l t s i n p a r t i a l d i f f e r e n t i a l equations f o r a region w i t h a moving boundary; such e q u a t i o n s a r e s o l v e d o n l y w i t h g r e a t d i f f i c u l t y "

I n t h e p r e s e n t a n a l y s i s , we have n e g l e c t e d t h e h e a t c a p a c i t y o f t h e mat e r i a l i n t h e f r o z e n f i l m and have assumed t h a t t h e temperature p r o f i l e s and t h e h e a t f l u x e s a r e t h e same as t h o s e t h a t would e x i s t a t s t e a d y

state.

The e f f e c t of t h i s assumption i s t h a t t h e c a l c u l a t e d r a t e o f move-

ment o f t h e s o l i d - l i q u i d i n t e r f a c e i s more r a p i d t h a n would a c t u a l l y b e the case.

We conclude t h a t t h e t i m e r e q u i r e d t o f r e e z e t h e f l u o r i n a t o r

i s s u f f i c i e n t l y long t o permit c o r r e c t i v e a c t i o n t o be t a k e n t o p r e v e n t

s a l t i n t h e f l u o r i n a t o r from f r e e z i n g . A s t h e f r o z e n film i n t e r f a c e moves t h e d i s t a n c e "daft i n time "de," t h e h e a t t h a t must flow through t h e f r o z e n f i l m c o n s i s t s of t h e h e a t b e i n g g e n e r a t e d i n t h e molten zone o f r a d i u s a , t h e l a t e n t h e a t o f f u s i o n g i v e n up by t h e material which h a s changed phase, and t h e s e n s i b l e h e a t c o n t a i n e d i n t h i s amount of l i q u i d as a r e s u l t of t h e change i n ternpera-

t u r e between t h e l i q u i d u s and t h e b u l k l i q u i d t e m p e r a t u r e s .

Neglecting

t h e l a s t contribution, t h e heat passing through t h e frozen f i l m ( p e r u n i t l e n g t h of f l u o r i n a t o r ) i s given by:

where

& = t o t a l . h e a t removed, W/m, h e a t of f u s i o n of t h e s a l t , W*sec/g, d e n s i t y o f t h e s o l i d s a l t , g/m 3

Âś

r a d i u s o f t h e molten zone, m ,

e =

time, sec,

P ( a ) = h e a t g e n e r a t i o n r a t e i n molten zone of r a d i u s a , W/m. With t h e assumption t h a t t h e h e a t c a p a c i t y of t h e f r o z e n f i l m i s

- t = a i n Eq. 1 ( 2 ) ] t o o b t a i n t h e f o l l o w i n g o r d i n a r y d i f f e r e n t i a l e q u a t i o n , which

n e g l i g i b l e , Eqs. ( 2 ) and (11)can b e combined [ w i t h r

approximates t h e dynamics o f t h e f r o z e n f i l m :

The h e a t o f f u s i o n , AH

w a s taken t o be

58 c a l / g ( r e f . 7 ) , and t h e

d e n s i t y o f t h e s o l i d s a l t w a s t a k e n t o be 3 . 4 g/cm

For t h e o p e r a t i n g

c o n d i t i o n s l i s t e d i n F i g . 8 , t h e h e a t g e n e r a t i o n r a t e can be expressed as :

-'(a) - - 0.00002326 n 2 I 2a 3.988 27-r

where n = turns/m, I = c o i l c u r r e n t , A, a = diameter of molten zone, cm.

Âś

c a1 s ec /cm ,

(13)

Fig. 8. Rate of Formation of the Frozen Salt Film.

26 S u b s t i t u t i o n of t h e v a l u e s f o r t h e c o n s t a n t s i n t o Eq. ( 1 2 ) , s u b s t i t u t i o n of Eq. (13) i n t o Eq. ( 1 2 ) , and assumption of a 5-in.-ID orinator yield

c o i l for the flu-

an e x p r e s s i o n f o r t h e time r e q u i r e d f o r t h e s o l i d - l i q u i d

i n t e r f a c e t o move from t h e edge of t h e c o i l t o t h e p o s i t i o n of r a d i u s a . The r e s u l t i n g e q u a t i o n i s :

a da

0.05478 0*00380 AT

(14)

0.00002326 n 2 I 2a3.988

A s shown i n F i g . 7 , t h e maximum s t a b l e f i l m t h i c k n e s s w i t h a c o i l c u r r e n t

of 11 A i s o b t a i n e d w i t h a temperature d i f f e r e n c e of 62Oc.

Calculations

were made w i t h an assumed temperature d i f f e r e n c e of 82Oc (2OoC g r e a t e r t h a n could b e allowed f o r s t e a d y - s t a t e o p e r a t i o n w h i l e m a i n t a i n i n g a frozen f i l m ) .

Other c o n d i t i o n s assumed i n t h e c a l c u l a t i o n were:

a coil

spacing of 78.7 t u r n s p e r m e t e r , and c o i l c u r r e n t s of 0 A and 1 1 A .

The

r e s u l t s o f t h e c a l c u l a t i o n s a r e shown i n F i g . 8 , which shows t h a t , w i t h no h e a t g e n e r a t i o n i n t h e molten zone, t h e time r e q u i r e d t o f r e e z e t h e f l u o r i n a t o r completely w i l l be g r e a t e r t h a n 1 . 5 h r .

With t h e h e a t gen-

e r a t i o n r e s u l t i n g from an 1 1 - A c o i l c u r r e n t , t h e time r e q u i r e d f o r comp l e t e f r e e z i n g w i l l be about 2.9 h r .

Equation ( 1 2 ) shows t h a t t h e

f r e e z i n g p r o c e s s can be r e v e r s e d by d e c r e a s i n g t h e temperature d i f f e r e n c e .

We conclude, on t h e b a s i s of t h i s a n a l y s i s , t h a t t h e f r o z e n f i l m t h i c k n e s s i n t h e f l u o r i n a t o r could be c o n t r o l l e d , without s e v e r e problems, by a d j u s t i n g t h e temperature of t h e w a l l of t h e f l u o r i n a t o r .

R e l i a b l e c o n t r o l of

t h e f r o z e n f i l m t h i c k n e s s could be accomplished most e f f e c t i v e l y by u s i n g a d i r e c t measurement of t h e f i l m t h i c k n e s s i n a feedback loop t o a d j u s t

t h e w a l l temperature.

We a r e a t t e m p t i n g t o d e v i s e a convenient method

for measuring t h e t h i c k n e s s of t h e f r o z e n f i l m . 3.3

Power Requirements f o r a n Experimental F l u o r i n a t o r

One of t h e purposes f o r making t h e p r e v i o u s a n a l y s i s was t o e s t i m a t e t h e s i z e of t h e high-frequency g e n e r a t o r t h a t would be r e q u i r e d f o r a 5-ftl o n g experimental f l u o r i n a t o r .

I n t h e f l u o r i n a t o r c o n s i d e r e d , t h e power

s u p p l i e d by t h e g e n e r a t o r would be d i s s i p a t e d as h e a t i n t h e molten s a l t i n t h e f l u o r i n a t o r , i n t h e i n d u c t i o n c o i l , and i n t h e m e t a l walls of t h e fluorinator.

E s t i m a t e s o f t h e amount o f h e a t g e n e r a t e d i n t h e molten

s a l t c o r e and i n t h e i n d u c t i o n c o i l can be made from r e l a t i o n s h i p s found i n s t a n d a r d t e x t b o o k s on i n d u c t i o n h e a t i n g ( e . g . , r e f . 8 ) .

However, no

r e l a t i o n s h i p s e x i s t i n t h e l i t e r a t u r e f o r estimating t h e heat generated i n a metal c y l i n d e r surrounding a c y l i n d r i c a l c o i l .

For our c a l c u l a t i o n s ,

we have assumed t h a t h e a t would be g e n e r a t e d i n t h e f l u o r i n a t o r v e s s e l a t t h e same r a t e as i n a v e s s e l which has a n o u t s i d e diameter e q u a l t o t h e i n s i d e diameter of t h e f l u o r i n a t o r and which is p l a c e d i n s i d e a c o i l having t h e same s p a c i n g and c a r r y i n g t h e same c u r r e n t as t h e c o i l i n t h e f l u o r i n a tor. We have assumed t h a t t h e f l u o r i n a t o r v e s s e l and t h e i n d u c t i o n c o i l w i l l b e made from n i c k e l s i n c e n i c k e l e x h i b i t s e x c e l l e n t r e s i s t a n c e t o f l u o r i n e when molt.en s a l t i s not p r e s e n t and s i n c e i t s s p e c i f i c e l e c t r i c a l r e s i s t i v i t y i s lower t h a n t h a t of o t h e r a l l o y s which might be used (prov i d i n g t h e c o i l t e m p e r a t u r e can be k e p t above t h e Curie t r a n s i t i o n tempe r a t u r e of n i c k e l , which i s 3 5 8 ' ~ ) .

A low s p e c i f i c r e s i s t i v i t y for t h e

c o i l m a t e r i a l r e s u l t s i n a low h e a t g e n e r a t i o n rate i n t h e c o i l . S u f f i c i e n t power can be g e n e r a t e d i n t h e molten s a l t t o m a i n t a i n a

s a l t f i l m 0.3 i n . t h i c k i n s i d e t h e c o i l w i t h a t e m p e r a t u r e d i f f e r e n c e of

5 1 째 C between t h e l i q u i d - s o l i d i n t e r f a c e and t h e i n d u c t i o n c o i l when t h e f o l l o w i n g c o n d i t i o n s a r e used: t o r v e s s e l made from 6-in.

a 5-ina-ID c o i l p l a c e d i n s i d e a f l u o r i n a -

sched 40 p i p e , a c o i l spacing o f 2 t u r n s p e r

i n c h , and a c o i l c u r r e n t of 11 A a t a frequency o f 400 kHz.

The e s t i m a t e d

h e a t g e n e r a t i o n rates i n t h e molten s a l t , t h e i n d u c t i o n c o i l , and t h e f l u o r i n a t o r v e s s e l w a l l a r e 1661, 133, and 42.7 W / f t ,

respectively.

t o t a l h e a t g e n e r a t i o n r a t e of a t l e a s t 9180 W would be g e n e r a t e d i n t h e c a s e o f a 5-ft-long

fluorinator.

The r e a c t a n c e of a 5-in.-ID

by 5-ft-long

c o i l i s v e r y l a r g e , and a

power f a c t o r o f 0.15 was e s t i m a t e d from s t a n d a r d e x p r e s s i o n s 8 f o r t h i s t y p e of c o i l .

With a power f a c t o r t h i s low, a g e n e r a t o r t h a t h a s a

r e a c t i v e power of 61,200 V-A i s r e q u i r e d .

I n o r d e r t o o b t a i n a c o i l cur-

r e n t of 11 A , more t h a n 5500 V would have t o be impressed a c r o s s t h e c o i l . The r e q u i r e d v o l t a g e can be reduced by d i v i d i n g t h e c o i l i n t o a number of s h o r t e r c o i l s t h a t have t h a t same diameter and spacing and a r e connected i n p a r a l l e l , w i t h a d j a c e n t c o i l s wound i n o p p o s i t e d i r e c t i o n s .

I f the

c o i l i s d i v i d e d i n t o 1 0 s e c t i o n s having 1 2 t u r n s p e r s e c t i o n , t h e est i m a t e d power f a c t o r would be 0 . 1 1 and t h e v o l t a g e t h a t must be impressed a c r o s s each c o i l would be about 760 V (which i s s t i l l u n d e s i r a b l y h i g h ) .

6 t u r n s per s e c t i o n , t h e power f a c t o r would be 0.093, and t h e r e q u i r e d v o l t a g e would b e about 450 V . I f t h e c o i l were d i v i d e d i n t o 20 s e c t i o n s h a v i n g

Although v o l t a g e s of t h e magnitude mentioned above would b e p o t e n t i a l l y hazardous and would complicate t h e removal of molten s a l t samples from t h e system d u r i n g o p e r a t i o n , t h e sampling hazard i s decreased by t h e f a c t t h a t t h e i n d u c t i o n c o i l must be e l e c t r i c a l l y i n s u l a t e d from t h e f l u o r i n a t o r vessel.

Use of a h i g h e r frequency may r e s u l t i n lower r e q u i r e d v o l t a g e

v a l u e s ; we w i l l i n v e s t i g a t e t h i s p o s s i b i l i t y l a t e r .

Even i f h i g h v o l t a g e s

a r e r e q u i r e d , we do n o t expect t o encounter any s e r i o u s problems i n providing the necessary e l e c t r i c a l insulation. I n e s t i m a t i n g t h e power requirements f o r t h e g e n e r a t o r , we have assumed t h a t t h e c o i l and p i p e a r e i n f i n i t e l y long and t h a t t h e v o i d s produced by bubbling f l u o r i n e through t h e molten s a l t w i l l not a f f e c t t h e h e a t g e n e r a t i o n r a t e ; a l s o , we have e s s e n t i a l l y assumed a v a l u e f o r t h e h e a t g e n e r a t i o n r a t e i n t h e m e t a l w a l l , although it i s probably not accurate.

The e f f e c t of t h e s e assumptions w i l l probably be t o d e c r e a s e

t h e e f f i c i e n c y of h e a t i n g t h e molten s a l t i n t h e f l u o r i n a t o r t o a v a l u e lower t h a n t h a t which we have e s t i m a t e d .

With a 5-ft-long

coil, the

magnetic f i e l d s t r e n g t h i s weaker t h a n t h a t p r e d i c t e d by e q u a t i o n s f o r an i n f i n i t e l y l o n g c o i l ; t h e r e f o r e , t h e h e a t g e n e r a t i o n r a t e i n t h e s a l t would be lower t h a n t h e c a l c u l a t e d v a l u e .

The presence o f bubbles w i l l probably

cause t h e h e a t g e n e r a t i o n r a t e t o be lower t h a n t h e r a t e t h a t would be obt a i n e d w i t h no bubbles p r e s e n t .

The bubbles would probably reduce t h e e f -

f e c t i v e c o n d u c t i v i t y of t h e s a l t , and hence t h e h e a t g e n e r a t i o n r a t e , s i n c e t h e h e a t g e n e r a t i o n r a t e i n t h e s a l t i s d i r e c t l y p r o p o r t i o n a l t o t h e cond u c t i v i t y of t h e s a l t .

The importance o f t h e e f f e c t s mentioned above cannot b e e a s i l y determined by c a l c u l a t i o n s ; hence, w e p l a n t o c a r r y o u t experiments u s i n g an aqueous e l e c t r o l y t e s o l u t i o n (probab1;y HNO ) as a s u b s t i t u t e f o r

molten s a l t .

W e conclude t h a t i n d u c t i o n h e a t i n g appears t o be a r e a s o n a b l e means

f o r p r o v i d i n g a c o r r o s i o n - f r e e h e a t s o u r c e i n a molten s a l t f l u o r i n a t o r and t h a t t h e o p e r a t i o n a l problems which have been examined appear t o be tractable

DEVELOPMENT OF THE METAL TRANSFER PROCESS E , L. Youngblood E. L. Nicholson

L. E , McNeese W. F. S c h a f f e r , Jr.

An improved r a r e - e a r t h removal p r o c e s s h a s been d e v i s e d , based on t h e o b s e r v a t i o n t h a t r a r e e a r t h s d i s t r i b u t e s e l e c t i v e l y i n t o molten l i t h i u m c h l o r i d e from bismuth s o l u t i o n s c o n t a i n i n g r a r e e a r t h s and thorium,

Work

t h a t w i l l demonstrate a l l phases of t h e improved p r o c e s s , which i s known as t h e m e t a l t r a n s f e r p r o c e s s , i s under way.

The f i r s t e n g i n e e r i n g e x p e r i -

ment (MITE-1) f o r s t u d y i n g t h e removal o f r a r e e a r t h s from s i n g l e - f l u i d MSBR f u e l s a l t by t h i s p r o c e s s was completed d u r i n g t h e c u r r e n t r e p o r t i n g p e r i o d . The main o b j e c t i v e of t h i s experiment was t o demonstrate t h e s e l e c t i v e r e moval of r a r e e a r t h s ( L a and Nd) from a f l u o r i d e s a l t m i x t u r e c o n t a i n i n g thorium f l u o r i d e

4.1

Equipment and Materials Used f o r Experiment MTE-1

The experiment was performed i n a 6-in.-ID

c a r b o n - s t e e l vessel (shown

i n Fig. 9 ) , which h a s been d e s c r i b e d p r e v i o ~ s l y . ~ The v e s s e l c o n t a i n e d two compartments i n t e r c o n n e c t e d a t t h e bottom by a pool of molten bismuth t h a t

was s a t u r a t e d w i t h thorium.

s a l t (72-16-12 mole

% LiF-BeF2-ThF4) t o which

f i c i e n t q u a n t i t y o f LaF

had been added.

One compartment c o n t a i n e d MSBR f u e l c a r r i e r

2 m C i of 1471'Jd and a s u f -

t o produce a lanthanum c o n c e n t r a t i o n of 0.38 mole

The o t h e r compartment c o n t a i n e d l i t h i u m c h l o r i d e , a cup

t h a t c o n t a i n e d a lithium-bismuth s o l u t i o n , and a pump f o r c i r c u l a t i n g t h e l i t h i u m c h l o r i d e through t h e cup.

The pump was c o n s t r u c t e d o f q u a r t z and

ORNL DWG 70-4504

CARBON- ST E E LPARTIT ION

/QUARTZ PUMP

TLiCI 72-16-12 MOLE Ye FUEL CARRIER SALT

F L i - Bi

Th-Bi

Fig. 9 .

Carbon-Steel Vessel f o r Use i n t h e Metal T r a n s f e r Experiment.

31 used s a p p h i r e b a l l s as check valves.'

L i t h i u m c h l o r i d e was f o r c e d i n

and out of t h e pump body by v a r y i n g t h e argon p r e s s u r e i n s i d e t h e pump E l e c t r i c a l probes were used t o d e t e c t t h e l i q u i d l e v e l i n t h e

chamber.

pump chamber and t o a c t u a t e

solenoid

p r e s s u r e d u r i n g a given pump c y c l e .

v a l v e s i n o r d e r t o change t h e argon Use of t h i s t y p e o f pump p e r m i t t e d ac-

c u r a t e c o n t r o l o f t h e flow o f l i t h i u m c h l o r i d e through t h e l i t h i m b i s m u t h container. I n o r d e r t o o b t a i n mixing i n t h e main bismuth p o o l , about 10% of t h e m e t a l volume was f o r c e d t o flow back and f o r t h every 7 min through a 1/2i n . slot below t h e p a r t i t i o n between t h e f l u o r i d e and c h l o r i d e compartments,

This flow w a s e f f e c t e d by reducing t h e p r e s s u r e of t h e argon cover

gas i n t h e f l u o r i d e compartment r e l a t i v e t o t h a t i n t h e c h l o r i d e compartment* Argon s p a r g e t u b e s were p l a c e d i n each s i d e of t h e v e s s e l as w e l l as i n t h e lithium-bismuth cup i n o r d e r t o promote c o n t a c t between t h e s a l t and m e t a l p h a s e s ,

Lumps o f thorium m e t a l ( a t o t a l of 501 g ) measuring

approximately 0 . 5 i n . on a s i d e were p l a c e d i n t h e bottom o f t h e v e s s e l i n o r d e r t o e n s u r e t h a t t h e bismuth phase w a s s a t u r a t e d w i t h thorium. The amount o f thorium added i n t h i s manner was about 20 times t h e amount E

t h a t could d i s s o l v e i n t h e bismuth,

The e x t e r i o r of t h e c a r b o n - s t e e l

v e s s e l used f o r t h e experiment was spray-coated w i t h n i c k e l aluminide t o p r e v e n t a i r o x i d a t i o n o f t h e carbon s t e e l . The q u a n t i t i e s of m a t e r i a l s used i n t h e experiment a r e shown i n Table

Most o f t h e m a t e r i a l s were p u r i f i e d t o remove o x i d e s and o t h e r impuri-

t i e s before t h e y w e r e i n t r o d u c e d i n t o t h e system.

The lithium chloride

was p u r i f i e d by c o n t a c t w i t h bismuth s a t u r a t e d w i t h thorium a t 650Oc. The c a r b o n - s t e e l v e s s e l and t h e bismuth used i n t h e experiment were f i r s t t r e a t e d s e p a r a t e l y w i t h hydrogen a t 6 5 0 " ~f o r about 1 2 hr for oxide removal.

The bismuth w a s t h e n added t o t h e c a r b o n - s t e e l v e s s e l and w a s sub-

s e q u e n t l y t r e a t e d w i t h hydrogen a t 6 5 0 " ~f o r an a d d i t i o n a l 1 0 hr. MSBR f u e l c a r r i e r s a l t (72-16-12mole t h e Reactor Chemistry D i v i s i o n ,

Purified

% LiF-BeF2-ThF4) was o b t a i n e d from

The argon used f o r cover gas and for op-

e r a t i o n of t h e l i t h i u m c h l o r i d e pump was p u r i f i e d by passage through a molecular s i e v e d r y e r and a bed o f uranium t u r n i n g s o p e r a t e d a t 600Oc.

43 43 M

m 0 c-

c-.

u3 M

.rl

cu m

The f i r s t q u a r t z pump used i n t h e experiment f a i l e d t o o p e r a t e p r o p e r l y ; when we attempted t o o p e r a t e t h e pump t o b e g i n t h e experiment, we found t h a t t h e check v a l v e s were s t u c k .

T h e r e f o r e , t h e system was

cooled t o 300째C and t h e pump was r e p l a c e d w i t h a second q u a r t z pump of

a similar d e s i g n .

The l a t t e r pump o p e r a t e d s a t i s f a c t o r i l y throughout

t h e experiment

4.2

Experimental Procedure

The sequence of o p e r a t i o n s c a r r i e d o u t d u r i n g t h e experiment can b e d e s c r i b e d as f o l l o w s .

The l i t h i u m c h l o r i d e was pumped through t h e l i t h i m -

bismuth c o n t a i n e r for 3 h r a t t h e flow r a t e o f about 25 cm3/min.

Pumping w a s t h e n stopped, and t h e system was allowed t o approach e q u i l i b r i u m d u r i n g a 4-hr p e r i o d .

A t t h e end of t h i s p e r i o d , f i l t e r e d samples of t h e

s a l t and bismuth phases were t a k e n .

was r e p e a t e d f o r 11 c y c l e s .

A s shown i n F i g . 1 0 , t h i s sequence

Three a d d i t i o n a l c y c l e s were c a r r i e d o u t i n

which t h e pumping p e r i o d was i n c r e a s e d t o 6 h r and t h e e q u i l i b r a t i o n per i o d was o m i t t e d .

During t h e pumping and e q u i l i b r a t i o n p e r i o d s , a por-

t i o n of t h e main bismuth pool was f o r c e d back and f o r t h between t h e f l u o r i d e and t h e c h l o r i d e compartments a t a r a t e e q u i v a l e n t t o 10% o f t h e metal volume every 7 min.

The experiment was c a r r i e d o u t a t 6 6 0 O c .

During t h e 5-day o p e r a t i n g p e r i o d , t h e pump was o p e r a t e d 50.5 h r and

81.2 l i t e r s of l i t h i u m c h l o r i d e was c i r c u l a t e d through t h e l i t h i u m - b i s muth c o n t a i n e r .

The f i l t e r e d samples t a k e n d u r i n g t h e experiment were

p r e p a r e d f o r analysis by cutting off the f i l t e r s e c t i o n w i t h tubing c u t t e r s and c l e a n i n g t h e e x t e r n a l s u r f a c e s w i t h emery c l o t h .

The 14$d

a c t i v i t y i n each sample was determined by d i r e c t counting o f t h e 0.53MeV gamma rays e m i t t e d by t h e sample. each sample

The lanthanum c o n c e n t r a t i o n i n

w a s determined by n e u t r o n a c t i v a t i o n ,

ORNL DWG 7 0 - 6 2 5 6

PUMPING TIME PER CYCLE = 3 hr EQUILIBRATION TIME PER CYCLE = 4 hr SAMPLE TIME PER CYCLE =-I h r

- - - - - - - - - - - - - - -

PUMPING

-----------

EQUlL 16 RATION SAMPLING

TOTAL PUMPING TIME = 5 0 . 5 hr TOTAL VOLUME PUMPED = 81.2 LITERS NUMBER OF SAMPLES TAKEN OF EACH PHASE = I 5

HEAT UP

Fig. 10. Operating Schedule f o r Metal Transfer Experiment MTE-1.

4.3 Experimental Results During the experiment the rare earths should have distributed between the salt and metal phases in a manner depending on the concentration of reductant in the metal phase.

The relative amount of rare earth in a salt

and metal phase at equilibrium can be expressed by the distribution coefficient, which is defined as:

-- mole fraction of M in the bismuth phase mole fraction of M in the salt phase

At equilibrium, a portion of the rare earths originally present in the fluoride salt would have been extracted into the bismuth phase, from which it should have distributed into the lithium chloride. The lithium concentration in the lithium-bismuth solution (35 at. % lithium) was sufficiently high that, at equilibrium, essentially all of the neodymium and lanthanum would be removed from lithium chloride in contact with this metal phase. Therefore, continued circulation of the lithium chloride through the lithium-bismuth cup should have gradually removed the neodymium and lanthanum from the fluoride salt and deposited these materials in the lithiumbismuth solution. The concentrations of lanthanum, neodymium, and 228Ra, a decay product of 232Th, were determined in the salt and bismuth phases periodically throughout the experiment. These data are summarized in Table 6. Values for the distribution coefficients thus obtained were relatively constant during the run.

As .hewn in Figs. 11 and 12, the average values for the

distribution coefficients between the fluoride salt and bismuth for lanthanum and neodymium were 0.044 and 0.073, respectively. The distribution coefficient values are in good agreement with values obtained in previous studies.lo Distribution coefficient values for lanthanum and neodymium between the bismuth and lithium chloride are shown in Figs. 13 and 14. These data show considerable scatter during the first two-thirds of the experiment because of the low concentrations of rare earths in the lithium chloride. The neodymium concentration in the lithium chloride was too low to be determined accurately, and the lanthanum concentration was lower than

ORNL DWG 70-6269RI

0.07

0.064 CALCULATED VALUE

0.590

0.167

0.06

0.05 0 0

0.04 0 0

0.03

a,? 0.02

0.01

\ 1 I6 I

I b b

1011

1 3 1 4 1 5

SAMPLE NUMBER

F i g . 11. D i s t r i b u t i o n C o e f f i c i e n t f o r Lanthanum Between F l u o r i d e S a l t and Bismuth S a t u r a t e d w i t h Thorium During Metal T r a n s f e r Experiment MTE-1.

ORNL OWG 70-6257 RI

0 .IO

0.09 0.08 0.07 0.06

0.05

~ 0 . 0 6 CALCULATED 4 VALUE

0 0 0

U I

0.04

l i

0.03

0.02

0.01 -

Fig. 12. Distribution Coefficient for Neodymium Between Fluoride Salt and Bismuth Saturated with Thorium During Metal Transfer Experiment MTE-1.

ORNL DWG 70-6275RI

J I

Fig. 13. D i s t r i b u t i o n C o e f f i c i e n t f o r Lanthanum Between LiCl and B i s muth S a t u r a t e d with Thorium During Metal T r a n s f e r Experiment MTE-1.

9 -

87.0 CALCULATED VALUE 7 0

U :4 Z

6 7 8 9 1011 SAMPLE NUMBER

1415

Fig. 14. Distribution Coefficient for Neodymium Between LiCl and Bismuth Saturated with Thorium During Metal Transfer Experiment MTE-1.

expected. These results probably indicate that the contact between the bismuth and lithium chloride phases was not sufficient to maintain equilibrium during this period.

An argon sparge tube was inserted into the

lithium chloride about midway through the run, and during the last third of the experiment the average distribution coefficients for lanthanum

(2.8) and neodymium (5) between the bismuth and lithium chloride phases (0.9 for La and 7.0 for Nd). were reasonably close to expected values'' The distribution of radium was also followed during the experiment. Most of the radium was introduced with the fluoride salt; a small amount was introduced with the thorium metal that dissolved in the bismuth phase. During the experiment, the radium slowly transferred from the fluoride salt to the lithium chloride and lithium-bismuth phases, as shown in Fig. 1 5 . At the end of the experiment, 72% of the radium was in the lithium chloride,

15% was in the fluoride salt, 12% was in the lithium-bismuth solution, and less than 1% was in the bismuth-thorium solution. Approximately 50% of the lanthanum and 25% of the neodymium (after correcting for 147Nd decay) originally present in the fluoride salt were removed during the experiment, Figure 16 shows the decrease in the lanthanum and neodymium concentrations in the fluoride salt as a function of pumping time and run time. The rates at which the rare earths were removed are in agreement with the expected removal rates. However, the lanthanum and neodymium removed from the fluoride salt did not collect in the lithium-bismuth as expected. No neodymium was detected in the lithium-bismuth solution during the run, and only a small fraction of the lanthanum (~1%) was collected in the lithium-bismuth. The concentration of lanthanum in the lithium-bismuth solution during the experiment is shown in Fig.

17. At the conclusion of the experiment most of the

rare earths that had been removed from the fluoride salt were found in a layer of material located at the interface between the LiCl and the thorium-saturated bismuth.

Reaction of oxide impurities in the system

with the rare earths is thought to have caused the rare earths to deposit at the lithium chloride--bismuth-thorium interface rather than in the

lithium-bismuth solution. Details are given in the following section.

ORNL OWG 71-7856

IO0

LiCl

a [L

160

2 0 k LL

5 40

\ -

20 -

\ a 0

FLUORIOE SALT Li-Bi

â&#x20AC;&#x2DC; 0

Bi-Th

24 PUMPING TIME (hours)

a 0

I 36

48 50.5

Fig. 1 5 . Distribution of Radium Between Fluoride Salt, Bismuth Saturated with Thorium, and LiCl During Metal Transfer Experiment MTE-1.

ORNL DWG 70-11,002 R 1

P 0.9a

0.8-

f I

z a

0.7 -

0.6-

a v)

I ta 0.5-

a W W

a a K iL

0 NEODYMIUM (AFTER CORRECTING FOR DECAY)

X LANTHANUM

0.4-

0 Io a a (L

Fig. 16. Rate of Removal of Neodymium and Lanthanum from t h e F l u o r i d e S a l t i n Metal T r a n s f e r Experiment MTE-1.

2 0

i i \

0 rc)

4.4

P o s t o p e r a t i o n a l Equipment Examination

A t t h e end of t h e experiment, t h e c a r b o n - s t e e l v e s s e l was c u t a p a r t

for inspection.

Most of t h e L a and Nd t h a t had been removed from t h e

f l u o r i d e s a l t d u r i n g t h e experiment was found i n a l / a - i n . - t h i c k

layer

of b l a c k material l o c a t e d a t t h e i n t e r f a c e between t h e l i t h i u m c h l o r i d e and t h e bismuth t h a t was s a t u r a t e d w i t h thorium.

Chemical a n a l y s i s showed

% L a , 7.7 wt % Th, 1 2 wt % L i , 0.95 w t % C1, 4.4 w t % 0, w i t h t h e remaining m a t e r i a l

t h e b l a c k l a y e r t o c o n t a i n 3.6 w t

% Si, 0.54

b e i n g bismuth.

% Fe, 59

Thorium oxide and l i t h i u m c h l o r i d e were t h e o n l y compounds

t h a t c o u l d be p o s i t i v e l y i d e n t i f i e d by X-ray d i f f r a c t i o n .

Thorium oxide

was expected t o be p r e s e n t a t t h e p o i n t where t h e b l a c k m a t e r i a l vas found,

as t h e r e s u l t of r e a c t i o n o f thorium w i t h oxide i m p u r i t i e s i n t h e system. The chemical form of t h e r a r e e a r t h s i n t h e b l a c k material was not d e t e r -

minded; however, it i s b e l i e v e d t h a t t h e p r e s e n c e of oxide i n t h e system i s r e s p o n s i b l e f o r t h e accumulation of r a r e e a r t h s a t t h e i n t e r f a c e between

t h e l i t h i u m c h l o r i d e and t h e t h o r i u m - s a t u r a t e d bismuth r a t h e r t h a n i n t h e lithium-bismuth s o l u t i o n . t h e system i n two ways:

Oxide i m p u r i t i e s were probably i n t r o d u c e d i n t o (1)by d e t e r i o r a t i o n of t h e q u a r t z pumps, and

( 2 ) by exposure of t h e s a l t t o a i r d u r i n g i n s t a l l a t i o n of t h e second q u a r t z pump. Other a r e a s i n t h e system were a l s o checked f o r accumulation o f r a r e earths.

A l a y e r of m a t e r i a l approximately

1/8 i n . t h i c k was noted a t t h e

bottom o f t h e bismuth t h a t was s a t u r a t e d w i t h thorium.

The appearance o f

t h i s l a y e r was d i f f e r e n t from t h a t o f t h e remainder o f t h e m e t a l phase.

The m a t e r i a l was p y r o p h o r i c , and s p a r k s and yellow smoke could be produced by s c r a t c h i n g i t s s u r f a c e .

It c o n t a i n e d 20 w t

thorium and i s assumed t o

be composed of a m i x t u r e of thorium bismuthide p a r t i c l e s and bismuth.

Al-

though t h e Nd and L a c o n c e n t r a t i o n s i n t h i s l a y e r were about t e n t i m e s t h e c o n c e n t r a t i o n s of t h e r a r e earths i n f i l t e r e d samples o f t h e bismuth-thorium s o l u t i o n t a k e n d u r i n g t h e r u n , t h e a c t u a l r a r e - e a r t h i n v e n t o r y amounted t o o n l y about 3% of t h e t o t a l r a r e earths i n t h e system.

Lumps of u n d i s s o l v e d

thorium m e t a l could a l s o be seen i n t h e thorium-bismuth phase, which i n d i c a t e s t h a t s u f f i c i e n t thorium was p r e s e n t t o m a i n t a i n t h e thorium con-

46 centration in the bismuth at its solubility during the run. The carbonsteel dip tubes and portions of the quartz pump were examined for 1471Vd activity. No significant amounts of 147Nd were found on these components

or in the lithium chloride that had condensed in the upper portion of the vessel.

The carbon-steel vessel and other steel components showed

no evidence of corrosion. The quartz pump was also in reasonably good condition. The surfaces of the quartz that had been in contact with the lithium chloride were white in appearance, and the quartz was somewhat weaker than initially as the result of devitrification.

4.5 Design and Testing of a Carbon-Steel Pump Having Molten-Bismuth Check Valves Because of the difficulties encountered with the operation of quartz pumps for circulating the lithium chloride in metal transfer experiments, a carbon-steel pump having molten-bismuth check valves was designed and tested. The pump, shownschematically in Fig. 18, was operated with lithium chloride at a flow rate of about 25 cm3/min at 650'~ for about 2 weeks. The pump operated satisfactorily and appears to be suitable for use in future metal transfer process experiments.

5. STUDY OF THE PURIFICATION OF SALT BY CONTINUOUS METHODS R. B. Lindauer

L. E. McNeese

To date, the molten salt required for development work, as well as for the MSRE, has been purified from harmful contaminants (mainly sulfur, oxygen, and iron fluoride) by batch processes.

It is believed that the

labor costs associated with salt purification can be reduced considerably by the use of a continuous process for the most time-consuming operation, which is the hydrogen reduction of iron fluoride. Equipment'*

has been

installed in which molten salt and gas can be countercurrently contacted in a packed column to obtain data for design of a full-scale continuous salt purification facility.

ORNL DWG 70-8981 TO VEN T AND

'ARGON SUPPLY

ELECTRODES FOR LIQUID LEVEL MESUREMENT

I I I

DISCHARGE

I1/2" CARBON STEEL TUBING 28" LONG

1 I/4"CARBON STEEL -TUBING

MOLTEN BISMUTH

INTAKE

F i g . 18. Carbon-Steel Pump w i t h Molten-Bismuth Check Valves for Metal T r a n s f e r Experiments.

48 During t h i s r e p o r t i n g p e r i o d , t h e system w a s charged w i t h 28 kg of LiF-BeF2 (66-34 mole % ) , and t e n f l o o d i n g r u n s were c a r r i e d o u t u s i n g hydrogen and argon.

A f t e r t h e f i r s t f l o o d i n g r u n w i t h hydrogen had

been completed, t h e f e e d l i n e t o t h e column became plugged.

S i n c e oxide

i n t h e s a l t was b e l i e v e d t o b e c a u s i n g t h e r e s t r i c t i o n , t h e s a l t was t r e a t e d w i t h a H2-HF mixture.

Oxide exceeding t h e amount t h a t i s s o l u b l e

i n t h e s a l t was removed, as i n d i c a t e d by a n a l y s i s of t h e off-gas s t r e a m f o r w a t e r ; however, t h e plugging r e c u r r e d a f t e r s a l t was a g a i n f e d t h r o u g h t h e column.

The d i f f i c u l t y was a p p a r e n t l y caused by plugging o f t h e , 1 / 1 6 -

in.-diam h o l e s a t t h e bottom o f t h e i n l e t s a l t d i s t r i b u t i o n r i n g . no r e s t r i c t i o n was found i n t h e l/h-in.-OD

Since

f e e d l i n e , a 3/16-in.-diam

hole

was d r i l l e d through t h e i n n e r w a l l o f t h e d i s t r i b u t o r r i n g t o p r o v i d e a n a l t e r n a t e s a l t i n l e t and t h e f e e d l i n e was r e p l a c e d w i t h a 3/8-in.-diam line.

A f t e r t h i s m o d i f i c a t i o n , s a t i s f a c t o r y s a l t flow t o t h e column w a s

obtained.

D e t a i l s of t h e o p e r a t i o n s c a r r i e d o u t f o r t h e removal o f o x i d e

from t h e s a l t and of t h e f l o o d i n g r u n s are given i n t h e remainder o f t h i s section.

5.1

Batch Treatment o f S a l t f o r Oxide Removal

After t h e f i r s t r u n , most of t h e s a l t i n t h e system ( 1 3 . 3 l i t e r s )

was t r e a t e d w i t h a

4% HF-H2

m i x t u r e i n t h e f e e d t a n k for 9 h r .

A t the

b e g i n n i n g of t h e t r e a t m e n t p e r i o d , t h e s a l t w a s h e a t e d t o 6 5 0 t~o ~d i s s o l v e as much of t h e oxide as p o s s i b l e .

A s oxide w a s removed from t h e s a l t , t h e

t e m p e r a t u r e of t h e s a l t was slowly d e c r e a s e d t o a f i n a l v a l u e of 5 3 5 O C i n o r d e r t o i n c r e a s e t h e s o l u b i l i t y of HF i n t h e s a l t and t h e r e b y i n c r e a s e t h e r a t e o f r e a c t i o n between HF and t h e o x i d e . The off-gas s t r e a m from t h e oxide removal o p e r a t i o n was c o n t i n u o u s l y analyzed f o r water by

use o f a e l e c t r o l y t i c hygrometer, which waspreceded

by a NaF bed f o r removing HF.13

A t o t a l o f 580 ppm o f o x i d e was removed;

t h i s i s s l i g h t l y more t h a n t w i c e t h e s o l u b i l i t y o f Be0 i n t h e s a l t a t

650'C.

The average HF u t i l i z a t i o n was 30%.

49 5.2

Measured Flooding Rates During Countercurrent Flow of Molten S a l t and Hydrogen or Argon

During t h e f l o o d i n g r u n s , s a l t flow r a t e s of approximately 50 t o

400 cm /min were used w i t h argon and hydrogen flow r a t e s o f up t o 7 . 5 and about 30 l i t e r s / m i n , r e s p e c t i v e l y , as shown i n Table 7 . e r a t u r e of t h e column was 7 O O 0 C i n each c a s e .

The temp-

The p r e s s u r e drop a c r o s s

t h e column i n c r e a s e d l i n e a r l y w i t h i n c r e a s e s i n g a s flow r a t e as shown i n Fig.

19, which summarizes t h e b e s t d a t a from t h e t e n r u n s .

At the

flow r a t e s s t u d i e d t h u s f a r , t h e s a l t flow r a t e had o n l y a minor e f f e c t on p r e s s u r e drop.

I n t h e figure, points obtained with the higher salt

flow r a t e s u s u a l l y l i e n e a r t h e upper s i d e of t h e band, a l t h o u g h some d a t a s c a t t e r was observed.

Five of t h e t e n r u n s were t e r m i n a t e d when

t h e s a l t - g a s i n t e r f a c e was d e p r e s s e d below t h e s e a l l o o p i n t h e e x i t l i n e i n t h e column by t h e combined p r e s s u r e drop i n t h e off-gas l i n e and i n t h e column.

The maximum flow r a t e p o s s i b l e w i t h t h e p r e s e n t system

i s about 19% of t h e c a l c u l a t e d f l o o d i n g r a t e , a l t h o u g h smooth o p e r a t i o n

i s observed o n l y up t o about 1 2 % of t h e c a l c u l a t e d f l o o d i n g r a t e .

t h e h i g h e r flow r a t e s , o p e r a t i o n w a s e r r a t i c and t h e p r e s s u r e drop a c r o s s t h e column f l u c t u a t e d o v e r a range of 2 t o 3 i n . of s a l t .

The v a r i a t i o n

i n p r e s s u r e drop was p o s s i b l y t h e r e s u l t of poor s a l t d i s t r i b u t i o n a t t h e t o p of t h e column.

One r u n w a s c a r r i e d o u t i n which t h e system was op-

e r a t e d w i t h a h i g h s a l t - g a s flow r a t i o ( u s i n g an argon flow r a t e o f about 1liter/min).

The s a l t flow r a t e w a s i n c r e a s e d s t e p w i s e t o 280 cclmin;

t h e n , a f t e r 15 min a t t h i s c o n d i t i o n , t h e s a l t flow r a t e was i n c r e a s e d t o 3 400 cm /min f o r 5 mine No i n d i c a t i o n of f l o o d i n g was observed. The p r e s s u r e drop a c r o s s t h e column was about 30 i n . H20.

These o b s e r v a t i o n s

i n d i c a t e t h a t a column of t h i s t y p e should have a much h i g h e r c a p a c i t y

for an o p e r a t i o n , such as removal of oxide from s a l t by t r e a t m e n t w i t h H

2-HF,

i n which t h e HF u t i l i z a t i o n i s h i g h and low g a s - t o - s a l t

flow r a t i o s

can be used.

I n t h e f i n a l f l o o d i n g r u n , s t a b l e o p e r a t i o n was o b t a i n e d w i t h a s a l t flow r a t e o f 100cm3 /minand hydrogen flow r a t e s up t o 20 l i t e r s / m i n . T h i s hydrogen flow r a t e i s s u f f i c i e n t t o reduce 400 ppm o f i r o n ( a s Fe2+) from

. .

idhj

cc d mcd f f i -.rlP

0 M

\L)

L n

rl rl

0 3

trl

0 M

M Ln

Ln o\

cv X

cu x

. 3

0 rl

rl 0

5 M

0 0 rl CH

-P

5 3

*rl

d 3 k

-P

a, a, +,

-P

*rl

0 0 A-

-P

2 .rl

2 a, c, cd ffi cd

ORNL DWG 70-11,003

100-

10-

I c'

1 -

-I

COLUMN DATA HEIGHT = 81-in. DIAMETER = 1.38 -in.

PACKING 80.25-in. RASCHIG RINGS

IO0

Fig. 19. Column Pressure Drop During Countercurrent Flow of Molten Salt (66-34 mole % LiF-BeF2 ) and Either Argon or Hydrogen.

a 1 0 0 cm 3 /min s a l t stream, assuming t h a t t h e g a s and s a l t r e a c h e q u i l i b r i u m

a t 700째C; however, t h e mass t r a n s f e r c o e f f i c i e n t i s probably not s u f f i c i e n t l y h i g h t o a l l o w e q u i l i b r i u m t o be reached w i t h t h e p r e s e n t column h e i g h t (81 in. ).

SEMICONTINUOUS REDUCTIVE EXTRACTION EXPERIMENTS I N A MILD-STEEL FACILITY

B. A. Hannaford C. W. Kee L. E. McNeese Following r o u t i n e H -HF t r e a t m e n t o f t h e bismuth and s a l t i n t h e sys2 tem, t h e phases were t r a n s f e r r e d 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 . Then 90 g o f p u r i f i e d LiF-UF4 e u t e c t i c s a l t w a s added t o t h e s a l t phase t o produce a UF

4 c o n c e n t r a t i o n of about 0.0003 mole f r a c t i o n f o r t h e f i r s t mass t r a n s f e r

r u n (UTR-1).

Hydrodynamic performance d u r i n g t h e 140-min r u n was e x c e l l e n t ,

and t e n p a i r s of bismuth and s a l t samples were t a k e n . e r a t e d a t 63% and 82% o f f l o o d i n g ( a t a bismuth-to-salt

The column was opv o l u m e t r i c flow

r a t e r a t i o of u n i t y ) ; n e v e r t h e l e s s , v i r t u a l l y none of t h e uranium was ext r a c t e d from t h e s a l t due t o an o p e r a t i o n a l d i f f i c u l t y t h a t p r e v e n t e d r e d u c t a n t from b e i n g added t o t h e bismuth. D i s s o l u t i o n o f thorium i n t h e bismuth f e e d t a n k i n p r e p a r a t i o n f o r t h e second mass t r a n s f e r experiment proceeded slowly as t h e r e s u l t of poor mixing i n the tank, salt.

I n run UTR-2, 95% o f t h e uranium was e x t r a c t e d from t h e

The r u n w a s made w i t h a 200% e x c e s s of r e d u c t a n t o v e r t h e s t o i c h i o -

m e t r i c requirement and w i t h bismuth and s a l t f l o w r a t e s of 247 ml/min and 52 ml/min, r e s p e c t i v e l y .

These flow rates a r e e q u i v a l e n t t o about 83% o f

flooding

6.1

P r e p a r a t i o n f o r Mass T r a n s f e r Experiments

I n p r e p a r a t i o n f o r t h e f i r s t mass t r a n s f e r experiment w i t h uranium, t h e s a l t and bismuth were t r e a t e d w i t h H2-HF t o remove t r a c e s o f o x i d e s . The procedure was e s s e n t i a l l y t h e same as d e s c r i b e d e a r l i e r , t h a t t h e g a s flow r a t e (30% HF-H2) was o n l y 15 s c f h .

except

The u t i l i z a t i o n o f

53 HF d e c r e a s e d from an i n i t i a l v a l u e of about 30% t o 5 t o 10% d u r i n g most of t h e 15-hr t r e a t m e n t p e r i o d .

A t t h e end of t h e p e r i o d , it decreased

r a p i d l y t o about 1%. Following p e r i o d s o f hydrogen s p a r g i n g t o reduce i r o n f l u o r i d e , and argon s p a r g i n g t o remove HF, a 400-g charge of thorium metal was added t o t h e t r e a t m e n t v e s s e l i n o r d e r t o t r a n s f e r zirconium from t h e s a l t phase t o t h e bismuth phase and t o supply t h e n e c e s s a r y r e d u c t a n t i n t h e bismuth f o r t h e f i r s t mass t r a n s f e r experiment.

About

24 h r a f t e r t h e thorium metal had been added t o t h e t r e a t m e n t v e s s e l , t h e s a l t and bismuth phases were sampled and t r a n s f e r r e d t o t h e respect i v e feed tanks A 270-g b a t c h of LiF-UF4 e u t e c t i c s a l t was p r e p a r e d by p l a c i n g

51.6 g

of LiF and 231 g of UF4 i n a small g r a p h i t e c r u c i b l e i n which t h e materials were melted and sparged w i t h a HF-H2 mixture f o r about

6 h r a t 6 5 0 ' ~ . The

H -HF g a s flow r a t e w a s t o o low d u r i n g t h i s p e r i o d t o o b t a i n meaningful 2 gas samples w i t h o u t u p s e t t i n g t h e off-gas p r e s s u r e , and i n t u r n , t h e g a s flow r a t e and t h e composition o f t h e g a s .

Following t h e t r e a t m e n t p e r i o d ,

t h e e u t e c t i c mixture was s o l i d i f i e d and d i v i d e d i n t o two p a r t s .

A 90-g

p o r t i o n was added t o t h e s a l t f e e d t a n k i n p r e p a r a t i o n f o r t h e f i r s t mass 4

t r a n s f e r experiment (UTR-1). 6.2

Mass T r a n s f e r Experiment WR-1

The f i r s t uranium mass t r a n s f e r r u n (UTR-1)

was v e r y s u c c e s s f u l from

t h e s t a n d p o i n t o f hydrodynamics and demonstrated t h a t simultaneous samples of t h e bismuth and s a l t l e a v i n g t h e e x t r a c t i o n column can be t a k e n e a s i l y .

However, t h e r u n f a i l e d t o p r o v i d e mass t r a n s f e r d a t a f o r r e a s o n s d e s c r i b e d below. During t h e r u n , a uniform flow r a t e of each phase was maintained a t 100 ml/min (about 63% o f f l o o d i n g ) f o r 90 min, d u r i n g which seven s e t s of simult a n e o u s samples of t h e s a l t and bismuth streams l e a v i n g t h e column were taken.

Three a d d i t i o n a l sets of samples were t a k e n d u r i n g t h e 25-min p e r i o d

i n which t h e s a l t and bismuth flow r a t e s were i n c r e a s e d t o 130 ml/min ( a b o u t 82% o f f l o o d i n g ) .

The flow r a t e s were determined from t h e changes i n t h e

54 bismuth and s a l t volumes i n t h e f e e d t a n k s d u r i n g t h e r u n , as shown i n Analyses of t h e flowing bismuth samples f o r uranium and thorium

F i g . 20.

showed l i t t l e , if any, of t h e s e m a t e r i a l s ( < 2 ppm of U and

<4 ppm

of Yh).

A review of t h e procedure followed d u r i n g t h e e a r l i e r a d d i t i o n o f thorium

metal

t h e t r e a t m e n t v e s s e l showed t h a t most o f t h e thorium had f a i l e d

t o e n t e r t h e c r u c i b l e c o n t a i n i n g t h e bismuth and s a l t because a cube o f thorium had blocked t h e h o l e i n t h e g r a p h i t e c r u c i b l e c o v e r , c a u s i n g t h e thorium cubes t h a t were subsequently added t o come t o r e s t on t h e c r u c i b l e cover Uraniun a n a l y s e s of s a l t from t h e s a l t f e e d t a n k and from t h e s a l t r e c e i v e r v e s s e l were i d e n t i c a l (1200 ppm), which i n d i c a t e s t h a t t h e r e

w a s no t r a n s f e r of uranium from t h e s a l t .

This confirmed a n a l y t i c a l

r e s u l t s f o r t h e bismuth samples, which a l s o showed t h a t no t r a n s f e r o f uranium t o t h e bismuth phase o c c u r r e d d u r i n g t h e experiment; however, t h e uranium c o n c e n t r a t i o n s r e p o r t e d f o r t h e s e t of n i n e flowing s a l t samples averaged 1092 ppm; each v a l u e i n t h i s s e t was l e s s t h a n t h e expected v a l u e o f 1200 ppm. A p o s s i b l e e x p l a n a t i o n f o r t h e low uranium c o n c e n t r a t i o n s i n t h e flow-

i n g s a l t samples was c o n s i d e r e d and d i s c a r d e d . much as 3 v o l

If t h e s a l t c o n t a i n e d as

% e n t r a i n e d bismuth, t h e e f f e c t would b e a d e c r e a s e i n t h e

uranium c o n c e n t r a t i o n i n t h e sample t o about t h e average v a l u e observed s i n c e t h e bismuth c o n t a i n e d no uranium.

However, t h e a n a l y s i s o f random

s a l t samples i n d i c a t e d bismuth c o n c e n t r a t i o n s o f l e s s t h a n 80 ppm, or

l e s s t h a n approximately 0.003 v o l

%. S i m i l a r l y ,

t h e r e was no i n v e r s e

c o r r e l a t i o n of r e p o r t e d sample weights w i t h i n d i c a t e d uranium concentrations.

The entrainment d e t e c t o r ( l o c a t e d between t h e s a l t o u t l e t from

t h e column and t h e s a l t sampler) a l s o provided evidence t h a t bismuth entrainment i n s a l t l e a v i n g t h e column was l e s s t h a n ( p r o b a b l y much l e s s than) 1 . 5 vol

%, t h e entrainment r a t e t h a t would b e r e q u i r e d i n o r d e r

f o r t h e bismuth l e v e l i n t h e d e t e c t o r t o r e a c h t h e lower probe.

The b i s -

muth entrainment measurements were made w h i l e t h e column was o p e r a t i n g a t 82% o f f l o o d i n g ; t h e s a l t i n t h e d r a i n l i n e below 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 frozen during t h i s period.

+ +

t SAMPLE PAIRS

BISMUTH

-0-

SALT

Fig. 20. V d U e s o f Bismuth and S a l t Remaining i n Feed T a n k s v s Run Time for Run UTR-1. The bismuth and s a l t f l o w r a t e s were approximately e q u a l and had t h e v a l u e s of 100 ml/min for t h e p e r i o d 60 t o 150 min and 130 ml/min f o r t h e p e r i o d 150 t o 175 min.

56 Following experiment UTR-1,

t h e s a l t and bismuth were r e t u r n e d 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 i n p r e p a r a t i o n f o r experiment UTR-2.

6 . 3 Mass T r a n s f e r Experiment UTR-2 Because of t h e d i f f i c u l t y encountered i n adding thorium m e t a l t o t h e t r e a t m e n t v e s s e l p r i o r t o r u n UTR-1,

t h e thorium r e d u c t a n t for ex-

periment UTR-2 w a s added d i r e c t l y t o t h e bismuth f e e d t a n k .

The 192.5-g

charge d i s s o l v e d v e r y slowly i n t h e bismuth, p o s s i b l y because of i n a d e q u a t e a g i t a t i o n o f t h e m e t a l phase by t h e argon s p a r g e .

P e r i o d i c samples of t h e

metab phase ( t a k e n w i t h a s t a n d a r d f r i t t e d sampler and w i t h a g r a p h i t e l a d l e ) showed t h a t t h e thorium c o n c e n t r a t i o n w a s i n c r e a s i n g a t t h e r a t e of o n l y about 2 ppm/hr.

A f t e r 200 h r a t 540째C and 120 h r a t 6 3 0 " ~ , a f i l t e r e d

sample and a l a d l e sample i n d i c a t e d thorium c o n c e n t r a t i o n s of 750 ppm and 1100 ppm, r e s p e c t i v e l y .

These v a l u e s should b e compared w i t h t h e thorium

s o l u b i l i t y i n bismuth a t 540째C ( L e . , 880 pprn) and a material b a l a n c e value of

1165 ppm, assuming complete d i s s o l u t i o n of t h e thorium.

The b a l a n c e of t h e LiF-UF4 e u t e c t i c (180 g ) w a s added t o t h e s a l t f e e d t a n k t o b r i n g t h e uranium c o n c e n t r a t i o n t o about 3000 ppm.

Because

o f u n c e r t a i n t y i n t h e v a l u e f o r t h e thorium c o n c e n t r a t i o n i n t h e bismuth, a bismuth-to-salt

flow r a t e r a t i o of 5 w a s used f o r experiment UTR-2.

The f i r s t a t t e m p t t o begin r u n UTR-2 w a s h a l t e d by t h e f a i l u r e of bismuth t o t r a n s f e r from t h e bismuth f e e d t a n k .

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

w a s a p p a r e n t l y t h e open end of t h e f e e d t a n k d i p t u b e s i n c e t h e l i n e w a s c l e a r e d b y back-flowing argon through t h e l i n e .

After bismuth and s a l t

flow t o t h e column had been i n i t i a t e d , t h e bismuth flow r a t e w a s i n c r e a s e d t o about f i v e times t h e s a l t flow r a t e i n o r d e r t o a c h i e v e t h e d e s i r e d r u n conditions.

The flow rates of b o t h bismuth and s a l t were s t e a d y o v e r a

p e r i o d of about 40 min, as shown i n F i g . 21.

During t h i s p e r i o d , seven

p a i r s of samples were t a k e n of bismuth and s a l t s t r e a m s l e a v i n g t h e column; t h e bismuth and s a l t flow r a t e s were 247 and 52 ml/min, r e s p e c t i v e l y , corresponding t o o p e r a t i o n a t about 83% o f t h e column f l o o d i n g r a t e .

The s m a l l

v a r i a t i o n s i n t h e flow r a t e s d u r i n g t h i s p e r i o d a r e i n d i c a t e d by t h e c l o s e approximation t o s t r a i g h t l i n e s shown by t h e l i q u i d - l e v e l c u r v e s i n F i g . 21.

ORNL-DWG-71-9490

+ SAMPLE

PAIRS

TAKEN

18 '

BlSM UTH

-.-

SALT

Fig. 21. Uolwnesof Bismuth and Salt Remaining in Feed Tanks vs Run Time f o r Run UTR-2. Flow rates inferred from slopes; bismuth, 247 ml/min; salt, 52 ml/min. Fraction of flooding, 83%.

58 In addition to samples of the salt and bismuth streams leaving the column, samples were also taken from bismuth and salt feed and receiver tanks. The resulting data are tabulated in Table 8.

The fraction of

uranium extracted, based on the data from the salt samples, was 95%. The scatter in the uranium analyses of" the salt and bismuth streams leaving the column was larger than expected. A uranium material balance based on the average uranium concentration in salt leaving the column would require an average uranium concentration of about 230 ppm (as compared with the observed value of 174 ppm) in bismuth leaving the column. Zirconium concentrations in the bismuth samples were within about 25% of the expected values. Excellent agreement was observed between thorium and lithim concentrations in the bismuth stream leaving the column and in the bismuth receiver vessel. The thorium concentration in the bismuth fed to the column is believed to have been 659 ppm, as indicated by the amount of dissolved metals in the bismuth after the experiment. The quantity of reductant present in the bismuth during the experiment (thorium and lithium) amounted to a stoichiometric excess of about 200% over that required to reduce the uranium and zirconium in the feed salt. This experiment is important because it represents the first known demonstration of the continuous extraction of uranium from molten salt into bismuth containing reductant. The results indicate that high uranium removal efficiencies can be obtained in a packed column having a reasonable length, Additional experiments will be carried out in order to determine more exactly the mass transfer performance of packed column extractors over a range of operating conditions.

7 . MEASUREMENT OF AXIAL DISPERSION COEFFICIENTS IN PACICED COLUMNS

J. S. Watson

L. E. McNeese

Axial dispersion in the continuous (salt) phase can reduce the performance of packed column contactors that are proposed for the MSBR fuel processing system. Effects of axial dispersion will be most severe where

Table 8.

Summary o f Mass T r a n s f e r Data Obtained i n R u n UTR-2

Bismuth flow r a t e , 247 ml/min; s a l t flow r a t e , 52 ml/min F r a c t i o n of uranium t r a n s f e r r e d =

3000 - 150 = 0.95. 3000

U balance, flowing stream samples =

U e n t e r i n g B i = 1.53 m i l l i m o l e s / m i n = u l e a v i n g s a l t 2.10 millimoles /min ~~

Bismuth Phase Origin of Sample Feed t a n k s

U Conc. i n Salt Phase (ppm)

3000

(ppm) 21

U (meq/liter)

(ppm)

3.4

Zr (meq/liter) QO

(ppm)

llloa

Th (meq/liter)

109

(ppm)

Li (meq/liter)

27.6 65 54 62 46 46

61-7~

Flowing stream 7

4 26d 144 114 137 163 161 181

Flowing stream ave.

150

155 174

Receiver t a n k s

146

737a

Flowing stream 1 Flowing stream 2 Flowing stream 3 Flowing stream 4 Flowing stream 5 Flowing stream 6

224

223 138 140 197 140

36.3 36.3

22.4

22.7 31.9 22.7 25.1 28.2

24 21

18 25

9.3 10

9.3 8.9 7.6 11

330 390 320 300

55 64.9

270

420

47 39 45 33 33 34 28 37 34

53.3 50

6.8

140

8.9

310

23.3 51.6

308

51.3

"Questionable value. bCalculated as t h e d i f f e r e n c e : 'Most

1 4 4 m e q / l i t e r minus t h e sum of t h e concentrations of U , Z r , and L i .

probable v a l u e , based on average f o r flowing bismuth samples.

dQuestionable v a l u e ; not included i n c a l c u l a t e d average value.

47 39 51

'I'otai Dissolved Metals (meq/liter)

140'

high flow rate ratios are required. An experimental program is in progress in which axial dispersion coefficients in packed columns are measured under conditions similar to those in the proposed reductive extraction processes; in this program, mercury and water are used to simulate bismuth and molten salt. The measured axial dispersion coefficients will be used to estimate column performance in the proposed system. Devices for reducing axial dispersion in packed columns are also under development. The equipment and experimental technique used for these studies have been described previ0us1y.l~ The technique consists of injecting a tracer solution at a constant rate near the top of a packed column in which water and mercury are in countercurrent flow. The tracer tends to diffuse up-

stream in the continuous (water) phase as a result of axial dispersion caused by the downflowing mercury droplets. The system is allowed to reach steady state, and then the concentration profile of the tracer in the continuous phase is determined. As indicated previously, a semilogarithmic plot of relative tracer concentration vs distance down the column produces a straight line having a slope that is inversely proportional to the axial dispersion coefficient. During this reporting period, measurements were carried out in a 2-in.-ID column having a length of approximately

ft.

The column was packed with l/k-in.-diam solid cylinders or Raschig rings or 1/2-in.-diam Raschig rings. The packing, which was made of either poly-

ethylene or Teflon, is not wet by either mercury or water.

7.1 Experimental Results The results of six runs made with 1/4-in. Raschig rings are shown in Figs.

22 through 27. Data for five runs with 1/4-in. solid cylindrical

packing are shown in Figs. 28 through 32, and data obtained during 13 runs with 1/2-in.-diam Raschig rings are shown in Figs. 33 through 45. The data from all these runs are summarized in Tables 9-11, and are shown along with previous data from seven runs with 3/8-in.-diam Raschig ring packing in Fig.

46. In each case, the axial dispersion coefficient was independent of

the dispersed-phase (mercury) flow rate.

Dispersion coefficients for 3/8and 1/2-in. packing were also independent of the continuous-phase (water) flow rate; their values were 3.5 and 4.8 cm3/sec, respectively. Data for

ORNL DWG 71-8601

DISTANCE FROM WATER EXIT (in.)

Fig. 22. Variation of Normalized Tracer Concentration with Distance Along a 2-in.-diam Column Packed with 1/4-in. Raschig Ring Packing During Run 1.

DJSTANCE FROM WATER EXIT (in.)

Fig. 23. Variation of Normalized Tracer Concentration with Distance Along 2-in.-dim Column Packed with l/b-in. Raschig Ring Packing During Run 2.

O R N L D W G 71-9471

2 .o

I .o 0.9 0.8

0.7 0.6

0.5

0.4

0.3

0.2

0.I 0

V I

DISTANCE FROM WATER EXIT (in.)

Fig. 24. V a r i a t i o n of Normalized T r a c e r Concentration w i t h Distalnc e Along 2-in.-diam Column Packed w i t h 1/4-in. Raschig Ring Packing During Run 3.

ORNL DWG 71-8605

2 .o

I .o 0.9 0.8

0.7 0.6 0.5 0.4

0.3

0.2

0.I 0

DISTANCE FROM WATER EXIT (in.)

Fig. 25 Variation of Normalized Tracer Concentration with Distance Along 2-in.-diam Column Packed with l/h-in. Raschig Ring Packing During Run 4.

DISTANCE FROM WATER EXIT (in.)

Fig. 26. V a r i a t i o n of Normalized Tracer Concentration w i t h Distance Along 2-in.-diam Column Packed w i t h 1/4-in. Raschig Ring Packing During Run 5.

. .

Fig. 27. V a r i a t i o n o f Normalized T r a c e r C o n c e n t r a t i o n w i t h D i s t a n c e Along 2-in.-diam Column Packed w i t h 1 / 4 - i n . Raschig Ring Packing During Run 6 .

ORNL D W G 71-8594

Y I-

""0

DISTANCE FROM WATER EXIT (in.)

Fig. 28. Variation of Normalized Tracer Concentration with Distance Along 2-in.-diam Column Packed with 1/4-in. Solid Cylindrical Packing During Run 1.

DISTANCE FROM WATER EXIT (in.)

Fig. 29. Variation of Normalized Tracer Concentration with Distance Along 2-in.-diam Column Packed with 1/4-in. Solid Cylindrical Packing During Run 2.

ORNL D W G 71-9481

1.0 0.9 0.8

0.7 0.6 0.5 0.4

0.3

0.2 ,

I-

tV Z

L I

0.0 2

.---

' -

I I

1 I

I I

11 i i i i i i i i i i i i i 1 i / / i i i I i i i i i i i i i i 18 i ikii i i I 1 1 1 i i I i i I j 1 1 1 1 i l i i I / 1 i i i i l l 0

DISTANCE FROM WATER EXIT (in.)

Fig. 30. Variation of Normalized Tracer Concentration with Distance ng 2-in.-diam Column Packed with 1/4-in. Solid Cylindrical Packing Ale ing Run 3. DW

O R N L D W G 71-8599

2.0

t i l i i l i i 1 i i i i M - l - L l i i i i i I1 I i i i i i t i i i 1 i I i i I I i i i i i i I I I lii i i i i i i i i i M I 1.0 0.9 0.8 0.7 0.6

0.5 0.4

0.3

I 1 1

! I

! I r > ; !

I I

I 1

1 1

I . . - T I 1T1 j j [ I [ I I 1 I / I l l I I . , ~ , , , , ! , , , . , , , , , ! , , ! ! , . , , . , ! , . . . . l ! l ! . l l 1

I 1

0.2

0.I 0

DISTANCE FROM WATER EXIT (in.)

F i g . 31. V a r i a t i o n of Normalized T r a c e r Concentration w i t h Distance Along 2-in.-diam Column Packed w i t h 1 / 4 - i n . S o l i d C y l i n d r i c a l Packing During Run 4 .

ORNL DWG. 71-8600

-..0

DISTANCE FROM WATER EXIT (in.)

Fig. 32. Variation of Normalized Tracer Concentration with Distance Along 2-in.-diam Column Packed with 1/4-in. Solid Cylindrical Packing During Run 5.

___-___

I l l

___ ____

I I

___________________________________ ~____________-__

___

__________________

0.1

_______________ ___ ~

___________

Along 2-in.-diam Column Packed with 1/2-in. Raschig Ring Packing During Run 1.

ORNL DWG 71-8608

2.0

I I

I I 1 1 n

I I

I l l

! I

I I

I l l I

-eB 0

15 DISTANCE- FROM WATER =IT

(in.)

Fig. 34. V a r i a t i o n of Normalized T r a c e r Concentration w i t h D i s t a n c e Along 2-in.-diam Column Packed w i t h 1 / 2 - i n . Raschig Ring Packing During Run 2.

ORNL D W G 71-8606

-e

2? 0

I 1

0.3. 1 I 1 I

I 1

I I I I I

I I

/ I

I I I I I

I 1

I l l

TT--

! , I . ! ! , / . , , , , , ! ! , , I , ! ! ! , , I I , ! , , , ! , ! , .

/ I / / I I I I.1 , , !, ,! ,! , _ , , , , . , l l . _ . l I ~ _ I !

DISTANCE FROM WATER EXIT (in.)

Fig. 35. Variation of Normalized Tracer Concentration with Distance Along 2-in.-diam Column Packed with 1/2-in. Raschig Ring Packing During Run 3.

0.3 V I

I I I I I I I 1

I l l

I /

I I

I 1

I l l

Fig. 36. V a r i a t i o n of Normalized Tracer Concentration w i t h Distance Along 2-in.-diam Column Packed w i t h 1/2-in. Raschig Ring Packing During Run 4.

-..

DISTANCE FROM WATER EXIT (in.)

F i g . 3 7 , V a r i a t i o n of Normalized T r a c e r Concentration w i t h D i s t a n c e Along 2-in.-diam Column Packed w i t h 1 / 2 - i n . Raschig Ring Packing During Run 5.

O R N L O W 0 71-8607

2.0

I .o 0.9 0.0 0.7 0.6 0.5 0.4

0.3 0

0.2 I

I 1

I I

I l l

0.I 0

DISTANCE FROM WATER EXIT (in.)

F i g . 38. V a r i a t i o n of Normalized T r a c e r Concentration w i t h D i s t a n c e Along 2-in.-diam Column Packed w i t h 1 / 2 - i n . Raschig Ring Packing During Run 6.

ORNL DWG 71-8596

DISTANCE FROM WATER EXIT (in.)

Fig. 39. Variation of Normalized Tracer Concentration with Uistance Along 2-in.-diam Column Packed with 1/2-in. Raschig Ring Packing During Run 7.

*-I

Fig. 40. V a r i a t i o n of Normalized T r a c e r Concentration w i t h Distance Along 2-in.-diam Column Packed w i t h 1 / 2 - i n . Raschig Ring Packing During Run 8.

Along 2-in.-diam Run 9.

Column Packed with 1 / 2 - i n .

Raschig Ring Packing During

2.0

I .o

0.9 0.8

0.7 0.6

0.5 0.4

0.3

0.2

0.I 0

DISTANCE FROM WATER EXIT (in.)

F i g . 42. V a r i a t i o n o f Normalized T r a c e r Concentration with Distance Along 2-in.-diam Column Packed w i t h 1 / 2 - i n . Raschig Ring Packing During Run 10.

82 .-

O R N L D W G 71-9475

DISTANCE FROM WATER EXIT (in.)

Fig. 43. Variation of Normalized Tracer Concentration with Distance Along 2-in.-dim Column Packed with 1/2-in. Raschig Ring Packing During Run 11.

L c

01STANCE FROM WATER EXF (in.)

Fig. 44. V a r i a t i o n of Normalized T r a c e r Concentration w i t h Distance Along 2-in.-diam Column Packed w i t h 1/2-in. Raschig Ring Packing During Run 1 2 .

Along 2-in.-diam Column Packed with 1/2-in. Raschig Ring Packing During Run 13.

Table 9 .

Run

Table 10

Summary of Axial Dispersion Measurements with 1/4-in. Solid Cylinders in a 2-in.-diam Column VHg (ml/min)

vH20 (d/min)

De (cm'/sec

350

1.41

350

1.18

600

0.463

820

2.08

820

0.669

Summary of Axial Dispersion Measurements with l/h-in.-diam Raschig Rings in a 2-in.-diam Column vH20 (ml/min)

De (cm*/sec)

350

22.8

2.05

350

1.33

350

68.4

0.918

820

22.8

2.16

820

45.6

1.88

820

64.8

1.03

Run

Table 11. Summary of Axial Dispersion Measurements with 1/2-in.-diam Raschig Rings in a 2-in.-diam Column

vH20 ( ml /min )

Run

De (cmâ&#x20AC;&#x2122;/sec ~

380

6.48

380

4.78

655

3.25

655

4.59

655

4.52

655

4.66

655

137

4.68

1060

6.23

1060

6.65

1060

4.56

1060

137

3.53

1060

137

4.38

1060

137

5.80

~~~

O R N L DWG 71-9545

7 E

I / 2 in. RASCHIG R I N G S

A 7l

3/8 in. R A S C H I G RINGS

n A

0.9 0.8 0.7 0.6

0.5 c

0.4

0.3

1/2in. R A S C H I G R I N G S

0 0

114 in. R A S C H I G R I N G S 114 in. S O L I D C Y L I N D E R S

0.2

0 .I

20 30 50 70 100 W A T E R F L O W RATE ( m l / m i n 1

200

Fig. 46. Variation of Dispersion Coefficient with Water Flow Rate for Several Packing Materials in a 2-ir1,~diamColumn.

88 t h e 1/4-in.

packing i n d i c a t e t h a t t h e d i s p e r s i o n c o e f f i c i e n t i s i n v e r s e l y

p r o p o r t i o n a l t o t h e continuous-phase flow r a t e .

D i f f e r e n c e s between t h e

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 two l/b-in.-diam

packing m a t e r i a l s a r e

probably r e l a t e d t o t h e d i f f e r e n c e i n t h e packing v o i d f r a c t i o n s of t h e s e materials.

The d a t a appear t o p o r t r a y two t y p e s of b e h a v i o r , one f o r

1/4-

i n . packing and one f o r l a r g e r packing.

7.2

Comparison of R e s u l t s w i t h a P u b l i s h e d C o r r e l a t i o n

Experimental d a t a on a x i a l d i s p e r s i o n i n packed colwnns have been obt a i n e d by Vermeulen, Moon, Hennico, and Miyauchi,16 who r e p o r t e d a c o r r e l a t i o n f o r predicting axial dispersion.

T h e i r s t u d y involved s e v e r a l f l u i d s

which had a range of p h y s i c a l p r o p e r t i e s and a number of packing materials; however, as t h e a u t h o r s p o i n t e d o u t , t h e s t u d y d i d n o t i n c l u d e a s u f f i c i e n t l y wide range of t h e d i f f e r e n c e i n f l u i d d e n s i t i e s t o e v a l u a t e t h e e f f e c t o f t h i s variable.

The d a t a o b t a i n e d d u r i n g t h e p r e s e n t s t u d y a f f o r d

a test

of t h e Vermeulen c o r r e l a t i o n f o r f l u i d s t h a t have a l a r g e d e n s i t y d i f f e r e n c e . The p r e s e n t d a t a are compared w i t h t h e c o r r e l a t i o n of Vermeulen, Moon, Hennico, and Miyauchi i n F i g . 47, where t h e dimensionless q u a n t i t y EV d /D CP e The agreei s p l o t t e d a g a i n s t t h e dimensionless q u a n t i t y ( $ v / d V )ll2V /V PC d c' ment of t h e p r e s e n t experimental d a t a w i t h t h i s c o r r e l a t i o n i s remarkable s i n c e t h e c o r r e l a t i o n was developed from d a t a o b t a i n e d w i t h systems having d e n s i t y d i f f e r e n c e s between one and two o r d e r s of magnitude l e s s t h a n t h a t of t h e mercury-water

system.

The s c a t t e r of t h e p r e s e n t d a t a around t h e

curve i s not s i g n i f i c a n t l y g r e a t e r t h a n t h a t of t h e e a r l i e r d a t a . C l o s e r examination of t h e d a t a r e v e a l s a n a p p a r e n t d i f f e r e n c e between t h e c o r r e l a t i o n and t h e p r e s e n t d a t a w i t h r e g a r d t o t h e dependence of d i s p e r s i o n c o e f f i c i e n t on t h e flow r a t e s of t h e two p h a s e s .

However, it was

not p o s s i b l e t o cover a s u f f i c i e n t l y wide r a n g e of mercury and water flow

r a t e s t o confirm t h e s u s p e c t e d dependence.

0.1 8

I I I I I

ORNL DWG 71- 123 RI I 1 I l l I

V E R M E U L E N , MOON, H E N N I C O , AND MlYAUCHl CORRELATION

6 -

I l l '

4 -

2 -

0.01 -

8 -

6 -

$" SCLlD

0 .OOl 0.I

$I'

I 2

CYLINDERS

RASCHIG RINGS I

l 4

JI = 0.874

JI = 0 . 4 I l l 6 8

I 1.0

=0.314

= 0.71 I

8 1 0

l 4

Fig. 47. Comparison of Mercury-Water Data Obtained in This Study With the Vermeulen, Moon, Hennico, and Miyauchi Correlation.

I I I I 8 100

8. REFERENCES 1. M. J. Bell and L. E. McNeese, "MSBR Fuel Processing Using the Fluorination--Reductive Extraction and Metal Transfer Flowsheet ," Engineering Development Studies for Molten-Salt Breeder Reactor Processing No. 6 , ORNL-TM-3141 (in press).

2. L. M e Ferris, "Measurement of Distribution Coefficients in Molten Salt--Metal Systems,'' MSR Program Semiann. Progr. Rept. Aug. 31, 1970, ORNL-4622, p . 204.

3. R. W. Kessie et&., Process Design for Frozen-Wall Containment of Fused Salt , ANL-6377 (August 1961).

4. J. R. Hightower, Jr., C. P. Tung, and L. E. McNeese, "Use of RadioFrequency Induction Heating for Frozen-Wall Fluorinator Development Studies," Engineering Development Studies for Molten-Salt Breeder Reactor Processing No. 6 , ORNL-TM-3141 (in press).

5. S. Cantor (Ed.), Physical Properties of Molten Salt Reactor Fuel, Coolant , and Flush Salts , ORNL-TM-2316 (August 1968), p . 14.

6. J. W. Cook, MSR Program Semiann. Progr. Rept. Feb. 28, 1969, ORNLc

4396, p . 122.

7. S. Cantor (Ed.), &. Cit. , p. 25. 8. P. G. Simpson, Induction Heatin$, McGraw-Hill, New York, 1960, p. 141. 9. E. L. Youngblood et a. , "Metal Transfer Process Development," Engineering Development Studies for Molten-Salt Breeder Reactor Processing No. 6, ORNL-TM-3141 (in press). 10. MSR Program Semiann. Progr. Rept. Feb. 28, 1969, 0 ~ ~ ~ - 4 3 9p. 6 ,284.

11. MSR Program Semiann. Progr. Rept. Feb. 28, 1970, ORNL-4548, p. 291. 12. R. B. Lindauer and L. E. McNeese, "Continuous Salt Purification Studies," Engineering Development Studies for Molten-Salt Breeder (in press). Reactor Processing No 6 , ORNL-TM-31]-\1.

13. W.

S. Pappas, Anal. Chem. 38,

615 (1966).

14. L. E. McNeese, Engineering Development Studies for Molten-Salt Breeder Reactor Processing No. 3, ORNL-3138, p. 34.

16. T. Vermeulen, J. S. Moon, A. Hennico, and T. Miyauchi, Chem. Eng. Progr. 62, 96 (1966).

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