THE RADIOCHEMISTRY OF PLUTONIUM - Sciencemadness.org

a 50-ml Erlenmeyer flask and evaporate to dryness (2X) “on a sand bath after addition
of 2-ml portions of 16M nitric acid. Add 5.0 ml of 16~ nitric acid to dissolve the U.
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Transfer to a 50-rrd volumetric flask with water and make up to volume. Determine
U x-ray spectrometrically. For samples containing less U, use proportionately
smaller volumes of nitric acid and volumetric flasks (down to 5 ml).
Add approximately 100 mg of sodium nitrite to the aqueous raffinate from
the U separation to otidize the Pu to the quadrivalent state. Add 20 ml of tributyl
phosphate -Amsco-140 and equilibrate 1 min. (Amsco-140 is used as the inert diluent
to give a light organic phase. ) Discard the lower aqueous raffinate. Add 15 ml of
O.2~ hydrochloric acid and equilibrate 1 min. Allow the phases to separate and trans-
fer the aqueous phase to a 50’-rnl Erlenmeyer flask. Add 10 d of 0.2M HCL to the
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organic phase and repeat the stripping operation. Combine the aqueous strip solutions,
add 2 ml of 12M hydrochloric acid, and evaporate on a s and bath to reduce the volume
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to approximately 2 ml. Transfer the solution to a 15-ml glass centrifuge cone with a
transfer pipette and dilute to 7 ml with water. Add 0.5 ml of 207. hydroxylamine hydro-
chloride and let stand 15 min with occasional mixing. While mixing with a Pt stirring
wire, add 10M sodium hydroxide dropwise until plutonium hydroxide precipitates. Add
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10 drops of sodium hydroxide solution in excess and let stand for 5 min. (Evaporation
is not a satisfactory volume-reduction step, as it does not remove chloride. With the
nitrate introduced in the next step, oxidation of the Pu to the s exivalent state would
occur. ) Centrifuge for 5 min and discard the clear supernate. Wash the precipitate
with water, centrifuge for 3 rein, and discard the wash solution. Add 2.0 ml of 16~
nitric acid and stir to dissolve the precipitate. Heat the nitric acid solution in a
boil~g water bath for 20 min. (This treatment will destroy any polymeric Pu which
may be present and ensure complete oxidation of the Pu to the quadrivalent state. E
the precipitate were dissolved in hot 3M nitric acid, some oxidation to the sexivalent
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state would occur. ) Allow the solution to cool and dilute to volume in a 10Tml volum-
etric flask with water. Read the absorbance vs a reagent blank in l-cm cells at
475 nq.I and a slit width of 0.02 mm, Calculate the Pu present from a calibration
factor prepared from a series of standards carried through the hydroxide precipitation
step only.
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