Transplutonium Elements-Production and Recovery - American

CAW stream was routed to trenches (1) specially excavated in. Hanford ... A f t e r a d d i t i o n o f A 1 ( N 0 3 ) 3 t o p r o v i d e s a l t i n ...
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7 Solvent Extraction Process for Recovery of Americium-241atHanford P. C. DOTO, L . E . BRUNS, and W. W. SCHULZ

Downloaded by CORNELL UNIV on November 12, 2012 | http://pubs.acs.org Publication Date: July 20, 1981 | doi: 10.1021/bk-1981-0161.ch007

Rockwell Hanford Operations, Richland, WA 99352

Solvent e x t r a c t i o n [ t r i b u t y l phosphate (TBP)] operations t o recover plutonium from u n i r r a d i a t e d scrap have been performed at the Hanford S i t e s i n c e 1955. The aqueous r a f f i n a t e (CAW stream) from the TBP plutonium e x t r a c t i o n process c o n t a i n s , t y p i c a l l y , Mg+2

>

]

approximate

n i t r a t e s

1.7

2

are m o l a r i t i e s .

n i t r a t e

v o l % DBBP-xylene A l

2 +

DBBP

from

10 was

[ M g

f a i r l y

constant

+

1— [H+]

4

concentrations

t i o n

10"

j

Am

other

5 . 5 χ

j

6

when

addition

of

NaOH. Proper is

c r u c i a l

cium. i t y to

adjustment to

Kings!ey's(7)

must

be a d j u s t e d

achieve

Proper trated

adequate

adjustment

v i o u s l y

requires NaOH

to

to

careful

with

of

americium

NaOH

f o r

extract

solutions

leaves,

and from of

s i b l e

use d i l u t e

to

p a r t i t i o n

o f

Am

within of

a c i d i t y

of

ameri-

show in

that

t h e CAW

range

the

this

of

Over-addition

excess

HNO3

to

ob-

concen-

of

a c t i n i d e s

and separation.

course,

phase. range

addition

scavenge

a c i d -

0.1-0.3M

DBBP

narrow

in-line

which

t r ivalent

the

to

3 +

s o l u t i o n .

have

exceedingly

metal

f o r

americium

of

d i s p e r s i o n

and others

a f f i n i t y

3)

CAW s o l u t i o n

NaOH

and

i n t e r -

I n s u f f i c i e n t compete

with

extractant.

Pu(IV)

DBBP

control

solids

phase

DBBP

Siddall(8) tions

(Figure

unbuffered

fere

of

extraction

concentration

CAW a c i d i t y

hydroxide

a d d i t i o n

a

d i s t r i b u t i o n

of

an

DBBP

r e s u l t s

p r e c i p i t a t e s greatly

(neutralization)

s a t i s f a c t o r y

well

n i t r a t e - l o w

Pu(IV)

over

(0.1-0.25M) from

observed

that HNO3

co-extracted

that

from HNO3

DBBP-diluent

both

strong

s o l u t i o n s .

f o r Am(III) solutions

to

plutonium.

s o l u -

HNO3 The

makes

it

greater pos-

s e l e c t i v e l y The

r e s u l t i n g

In Transplutonium Elements—Production and Recovery; Navratil, J., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1981.

116

TRANSPLUTONIUM

acid

s t r i p

cation 2 1 f l

s o l u t i o n

exchange

Am.

from

s o l u t i o n . recycled

to

The of

the

DBBP

f o r

Downloaded by CORNELL UNIV on November 12, 2012 | http://pubs.acs.org Publication Date: July 20, 1981 | doi: 10.1021/bk-1981-0161.ch007

Fe3+,

into

the

iron

cal

flowsheet

and

ure

process 4

previous

subsequent

a

of

the

e f f e c t i v e l y d i l u t e

c a n be

of

HNO3-HF

conveniently

the mainline

2 +

,

e x c e l l e n t the

and M g of

of

HNO3 of

provides from

PRF

TBP

aluminum,

s t r i p

the

range

Flowsheet. of

operated,

in

of

S i g n i f i c a n t

factors

103

-

4

from

of

the

the

and

80-180

t y p i c a l

chemi­

countercurrent the

minor

values

s i x

years

changes c i t e d

used.

operations

in

aluminum.

the in

of

accompany

recovery

range

Over

generally

A m

f o r

5

n a t u r a l l y ,

those

Richardson(9_)

features

the

10

CAW s o l u t i o n .

p l a n t - s c a l e

and

because

Richardson(9j

Hanford

but

DBBP-CCI4

sodium 2 4 1

the

0.025,

p a r t l y

DBBP

in χ

v o l %

and

i l l u s t r a t e s

were,

of

1.5

at

and f l o w r a t e s ,

employed

r e s u l t s

χ

there

representative

i r o n ,

s o l u t i o n .

employed

Am

2 I f l

2

30

in

d i s t r i b u t i o n