Effect of cobalt-60 gamma radiation on the determination of uranium(IV) in phosphoric acid solutions of uranium(iv) oxide

The effect of ⁶⁰Co γ-radiation on aerated and deaerated phosphoric acid solutions of uranium(IV) oxide (UO₂) was studied as a function of temperature, concentration of UO₂, and radiation dose rate. The effect was measured in terms of the radiolytic yield of uranium(VI),Gu_VI. For solutions of high initial UO₂ concentration, Gu(VI) is largest for the aerated solutions at 25°; it is lowest for the deaerated solutions at 140°. The Gu(VI) is lower for the solution of low initial UO₂ concentration than for any of the solutions of high initial UO₂ concentration. At the high starting UO₂ concentration, the initial Gu(VI) values are always higher than the succeeding values; this effect is attributed to the depletion of oxygen originally present in the solution. Gamma radiation causes an error in the determination of the stoichiometry of UO₂; the error is a function of the radiation dose. This error can be minimized by excluding oxygen from solutions of UO₂ and by keeping the initial UO₂ concentration as low as possible.