Simulation of radiation damage in rocks considered for safe storage of nuclear waste

Abstract

Rock salt is one of the considered storage mediums for radioactive waste, and so the behavior of rock salt in the vicinity of the waste canisters is of great practical interest. The main contribution to the irradiation from a radioactive waste comes from gamma-radiation, which requires a comparison of its action with that of the electron irradiation, widely used for simulation of radiation damage in rock salt. Samples of synthetic crystals of NaCl have been electron and γ-irradiated and subsequently investigated by means of differential scanning calorimetry and atomic force microscopy. Our theoretical modeling of the irradiation damage has shown that the observed difference in colloid production under electron and gamma irradiation may be explained by the difference in the dose rates rather than the irradiation type. The data on radionuclide migration in the geological medium material of the disposal site are required for estimating the ecological safety of the radioactive waste disposal system in granite and tuff rocs. Penetration profiles of cerium 139 Ce in granite and tuff specimens (before and after γ-irradiation) were measured by means of nuclear physics methods.