SIMULATION OF RADIATION-CHEMICAL BEHAVIOR OF NEPTUNIUM IN PERCHLORIC-ACID .1. REDUCTION OF NP(VI) AND OXIDATION OF NP(V)

Simulation of radiochemical reduction of Np(VI) in 0.35-6.0 M HClO4 an d oxidation of Np(V) in 4.0-6.0 M HClO4 was carried out. The agreement between the calculated and experimental radiochemical yields and kine tic curves is observed when Np(VT) is reduced by the products of water radiolysis (H, HO2, and H2O2) and Np(V) is oxidized by the products o f perchloric acid radiolysis (ClO3-, ClO2, ClO2-, ClO, ClO-, and Cl) a nd by OH radicals. The role of reaction with ClO3- ions in the Np(V) o xidation is predominant. The mechanism and kinetic relationships of ra diolytic oxidation of Np(V) are evaluated, and the rate constants of r eactions of Np(V) with ClO3- and other products of perchloric acid rad iolysis are determined.