Modelling Stable-Fission-Gas Diffusion Inside the Grain

Abstract

A new analytical solution for the diffusion of fission-gas atoms inside the UO₂ fuel grain has been obtained. This solution and a related numerical procedure model fission-gas atom migration to the grain boundary under varying conditions of temperature and fission power and including the grain growth process. This new formulation is presented and its improvements and advantages are outlined. The fission-gas release results obtained with a developmental version of ELESIM which incorporates this new model, as well as some other improvements are presented.