THE RADIOCHEMISTRY OF PLUTONIUM - Sciencemadness.org

Procedure 5. Plutonium D. C, Hoffman (Ref. 185)
Outline of Method
The essentially specific procedure for Pu utilizes the almost quantitative
carrying of Pu(IV) on lanthanum fluoride and also the great difference in ability of
Pu(III) and Pu (IV) in 12 ~ HC1 medium to be absorbed on a Dowex A-1 anion resin.
One cycle of the procedure serves to separate Pu from other a-emitters, and two
cycles usually gives complete decontamination from ~-emitting fission products.
The initial lanthanum fluoride precipitation, carried out in the presence
of hydroxylamine, is an excellent volume-reducing step and also eliminates many
elements (notably iron) which may interfere in the subsequent adsorption of Pu on
the resin column. After dissolution of the lanthanum fluoride precipitate in 12 ~
HC1, adsorption on the anion resin column of Np, Pu, and any traces of Fe and U
present is effected, while the rare-earths Am and Cm pass through the column. Pu
is eluted from the column after reduction to Pu(IH) with hydriodic acid; NTP is not
reduced to the +3 state and remains quantitatively behind. (A solution containing 15
pg of U235 was run through the procedure, and no fission counts above tbe usual
background of 0.1 - 0.2 smidgins (1 smidgin = 10-6 mg) could be detected. )
The Pu is collected directly from the resin column on 2-in. Pt plates
which are flamed, a-counted, and, if necessary, pulse-analyzed. The plates are
usually very clean and may be a-pulse -analyzed with a resolution of 1 - 1. 5Y0.
Samples are usually run in quadruplicate and yields are determined in
one of two ways. PU236 tracer to the extent of about one-fourth to one-half of the
total Pu @-activity expected may be added to one or two of the original aliquote. on
completion of the analysis, the fraction of PU236 in the sample is determine by pulse
analysis, thus permitting the calculation of yield. Yields may also be determined by
spiking two of the four samples with a standardized solution of Pu activity which is
at least five times as active as the aliquot to be analyzed. The average of the number
of cpm in the two unspiked samples is subtracted from the average in the two spiked
samples. The resulting value divided by the number of cpm in the spike gives the
yield. The chemical yield is usually about 9’77. and for a set of four aliquots analyzed
simultaneously is constant to within + 1%. In analysis of solutions of very high ionic
strength the yields are somewhat lower (90-97yo), probably because ~der these con-
ditions the lanthanum fluoride carrying step is less efficient. Quadruplicate analyses
can be performed in 3 h,
Reagents
La carrier: 5 mg La/ml (added as La(N03)3 . 6H20 in H20)
PU236 standardized tracer solution (in 3 ~ HC1),
or
Pu standardized spike solution (any mixture of Pu isotopes in 3 ~ HC1),
HC1: cone. (12~)
HC1: 3~
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