Radiation chemistry of plutonium (VI)

Radiation induced redox reactions of Pu(VI) have been investigated under different conditions. Radiolytic oxidation of Pu(VI) to Pu(VII) has been studied in air equilibrated alkaline solutions in the presence of K2S2O8. The radiolytic yield of Pu(VII) has been found to increase with the increasing concentration of K2S2O8 and also of Pu(VI) up to 0.75 mol m-3. On the basis of experimental data a maximum value of G[Pu(VII)] = 5.1 could be estimated in air equilibrated solution. On the other hand radiolytic reduction of Pu(VI) to Pu(V) has been investigated in hydrogen equilibrated solutions of Pu(VI) at pH in the range of 3 to 5. It has been observed that G[Pu(V)] decreases from 5.68 to 1.95 ions/100 eV with the increase of radiation dose from 3.8 x 1021 to 3.93 x 1022 eV dm-3. The mechanisms of these redox reactions are discussed. (author)