Mechanism of the radiolytic reduction of quadrivalent cerium in aqueous hydrochloric acid solutions at high-absorbed dose rates

Abstract

1. The yields of Ce3+ and the sum of peracids H2S2O8 + H2SO5 were determined in the radiolysis of sulfuric acid solutions of ceric sulfate at dose rates of up to 1023 eV/ml · sec. 2. The dependence of G(Ce3+) and G(H2S2O8 + H2SO5) on the H2SO4 and Ce3+ concentrations was investigated at a dose rate of 1023 eV/ml · sec. The yields decrease with increasing Ce3+ concentration. When the H2SO4 concentration is increased, the yield of peracids increases, while the yield of Ce3+ decreases. 3. At a low dose rate, peracids are formed as a result of the direct action of radiation on sulfuric acid. 4. The possible mechanism of the radiolytic transformations of the Ce4+ and Ce3+ ions and the formation of peracids at high absorbed dose rates was considered. 5. The values of the relative rate constants of a number of radiochemical reactions proceeding in aqueous sulfuric acid solutions of Ce4+ and Ce3+ were calculated.