Gamma radiolysis of NaCl brine: Effect of dissolved radiolysis gases on the radiolytic yield of long-lived products

Five moles per litre NaCl solution is γ-irradiated in autoclaves at 35 °C and 90 °C. H2, O2 and ClO 3 - are formed as long-lived products and reach equilibrium concentrations at a gas partial pressure of some 10 bar. Since formation of a gas phase is completely suppressed, H2 and O2 are kept dissolved. The equilibrium concentration level depends on dose rate and pH. Experiments at 90 °C and with added H2 show no gas production at all. From the kinetic simulation of the experiments we deduce that the reaction of OH and Cl 2 - radicals with H2 limits or inhibits sustaining solution decomposition. If species are present which compete with the radicals for H2, (such as Br−) the decomposition is promoted. In such a case the gas partial pressure exceeds 100 bar.