Water radiolysis and its effect upon in-reactor zircaloy corrosion

Abstract

Abstract The well-known effects of dissolved oxygen and hydrogen in respectively increasing and reducing the corrosion rate of zircaloys irradiated in high temperature water have been attributed to changes in the course of water radiolysis.1 Computer simulation of the growth and decay of radioly tic species produced by β, γ and neutron irradiation of water at 25°C and 305°C has been performed. In general, neutron irradiation leads to greater decomposition of water, and the effect of dissolved oxygen at 305°C is to markedly increase the concentrations of oxidizing radiolytic species. Correlation of zircaloy corrosion behaviour under such conditions with predictions of water radiolysis suggests that either HO2 of O− 2 are significant contributors to the corrosion enhancement phenomenon. Possible enhancement mechanisms are briefly discussed.