Computer simulation of radiation damage in NaCl using a kinetic rate reaction model

Abstract

Sodium chloride and other alkali halides are known to be very susceptible to radiation damage in the halogen sublattice when exposed to ionizing radiation. These radiolysis mechanisms have been studied for many years and the primary process, the production of F and H centres, is well understood now. The secondary processes of defect clustering are less well understood but there is substantial experimental evidence that, at temperatures above room temperature, F centres can coagulate and form metallic alkali colloids and that H centres will cluster, giving rise to the formation and growth of dislocation loops. The model presented in this paper is an extended version of the Jain-Lidiard model; its extensions comprise the effect of impurities and the colloid nucleation stage on the formation of radiation damage. The new model has been tested against various experimental data obtained from the literature and accounts for several well known aspects of radiation damage in alkali halides which were not covered by the original Jain-Lidiard model. The new model thus may be expected to provide more reliable predictions for the build-up of radiation damage in a rock salt nuclear waste repository.