THE RADIOCHEMISTRY OF PLUTONIUM - Sciencemadness.org

,02
D
10
I
‘o 5 10
Aqueous nltrlc acid concentratlankJ
Fig. 7. Effect of NaN03 on the distribution
of Pu(IV) between lg~o TBP in
kerosene and nitric acid solutions.44. 258
The salting-out effect of non-extractable
salts on the extraction of Pu and U has received
considerable attention.
165, 43, 149,52
Typical results are shown in Fig. 7 in which
Na(N03) is used as the salting agent for
Pu(IV ). 44, 258 At a constant total nitrate con-
centration the distribution coefficient decreases
as the proportion of nitric acid is increased,
but the distribution coefficient is always
greater than that of pure HN03. This effect
is caused by the reduction of competition for
TBP molecules by the lowering of the extract-
able nitric acid concentration.
Aluminum nitrate has been used as a
salting- out agent for Pu in several TBP extraction
processes.
149, 165, 52, 354
Applications of TBP-nitrate systems. Many papers have been written about
the application of TBP to the processing of irradiated U for
PU195, 132, 93, 148,325, 114, 202,365, 109, 133
The process involves extracting Pu(IV )
and U(VI) away from fission products into TBP-kerosene from nitric acid solutions,
stripping the Pu into a relatively concentrated nitric acid solution by reduction to Pu(IIf),
and finally stripping the U(VI) with water. Nitrous acid is added to the feed solution in
76
the first extraction to stabilize Pu(IV). Ferrous sulfamate was first used as a re -
ductant in the Pu stripping stage, 335, 195, 132 although U(IV) as a reductant has been extensively
studied.
209, 221, 67.385, 353, 342, 38
This reagent can be generated from
U(VI) and stabilized by volatile reductants, with the considerable advantage in large-
scale processing plants of not introducing non-volatile materials (e. g. irorr) into the
waste streams, thus permitting a smaller waste volume. The behavior of fission pro-
ducts and other elements in this process has received much attention, both in the primary
papers and others. 88,161,431,133,367
A variant has been described in which the fission
products, Pu and U, are successively stripped from the TBP phase by stepwise lowering
of the acid concentration.
203
TBP was used in the isolation of naturally occurring Pu. 315
Analytical
362
and radiochemical
144, 114
procedures for Pu based on TBP ex-
traction from HN03 have been given.
An interesting application is the use of TBP in reversed-phase chromatography for
various heavy element separations, 124’ 156’157’190 and for the separation of Pu(IIT),
Pu(IV) and Pu(VI) in HN03. 380
TBP – other aqueous systems. Tetra- and hexavalent actinides extract well
into TBP from moderately concentrated HC1 solutions, while trivalent species are
33