Analysis of migration of fission gas in grains exhibiting precipitaion and resolution under irradiation

An analytical model has been developed to predict the amount of fission gas contained in the UO2 matrix and intra-granular bubbles, and the amount released to the grain boundary as a function of irradiation conditions and time. It takes into account the relevant physical processes such as precipitation of fission gas atoms into intra-granular bubbles and irradiation-induced resolution from both intra- and inter-granular bubbles under the assumption that intra-granular bubbles are uniform in both radius and number density. Sensitivity stydy has been conducted to determine how the main physical parameters such as intra- and inter-granular resolution probabilities, grain raius, and termperature influence the fission gas release to the grain boundary. (Author)