Studies on radiolytic oxidation of plutonium(III) in hydrochloric acid medium

The effect of γ radiation on plutonium(III) was studied in argon and oxygen equilibrated hydrochloric acid solutions. The initial G values of Pu(IV) and H2O2 were found to be 6.5 ± 0.6 and 4.0 ± 0.4 respectively in oxygen equilibrated 0.8 mol dm-3 HCl solutions. While the G[Pu(IV)] increased to 8.0 ± 0.8 to 9.0 mol dm-3 HCl solutions. G(H2O2) decreased to 2.5 ± 0.3. In argon equilibrated 0.8 mol dm-3 HCl solutions, the G values of Pu(IV) and H2O2 were 5.0 ± 0.4 and 0.6 ± 0.1 respectively. It was observed that the initial yields of Pu(IV) decreased beyond a dose of 6 x 1018 eV cm-3 and there was incomplete oxidation of Pu(III) in 0.8 ml dm-3 HCl in both oxygen and argon equilibrated solutions, whereas Pu(III) in 9.0 mol dm-3 HCl was completely oxidised to plutonium(IV) in oxygen equilibrated solutions. The observed radiolytic yields of Pu(IV) and H2O2 are discussed in terms of reactions of Pu(III) with radiolytic products of water. Formation of brown peroxy complex was observed in oxygen equilibrated solutions of Pu(III) in 0.8 mol dm-3 HCl. (author)