Radiation damage of NaCl: dose rate effects

Abstract

The authors discuss the experimental results on radiation damage of NaCl single crystals in terms of the Jain-Lidiard model. This model has been improved by taking into account the back reaction between F centres and Cl2 molecules. It appears that with this extended Jain-Lidiard model they can describe quantitatively the experimental data of Jenks and Bopp (1974, 1977). From the analysis they conclude that there should be appreciable dose rate effects, which is in agreement with the experimental results published by Levy et al. (1981). Depending upon the temperature and the total dose these does rate effects may cause very large concentrations of radiation damage. The low dose rate region (104 rad h-1) is of special interest, because the rocksalt in a nuclear waste repository is subjected to ionising radiation of this intensity for a long period of time. Until now no experimental information on radiation damage in NaCl has been available under these conditions. In the present paper they have calculated the concentrations of radiation damage under the above mentioned conditions within the improved Jain-Lidiard model. It appears that these concentrations may be up to about one order of magnitude larger than the ones observed by Jenks and Bopp, who have carried out their radiation damage experiments at dose rates between 107 and 108 rad h-1.