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

Five moles per litre NaCI solution is γ-irradiated in autoclaves at 35 °C and 90 °C. H 2 , O 2 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, H 2 and O 2 are kept dissolved. The equilibrium concentration level depends on dose rate and pH. Experiments at 90 °C and with added H 2 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 H 2 limits or inhibits sustaining solution decomposition. If species are present which compete with the radicals for H 2 , (such as Br - ) the decomposition is promoted. In such a case the gas partial pressure exceeds 100 bar.