Transient induced creep for irradiated fuels

Creep of nuclear fuels under irradiation has generally been considered as an athermal process. A transient state of irradiation induced creep, however, was treated with kinetic equations based on thermodynamics. For this purpose, the kinetic equations for enhanced diffusion, annihilation of excess vacancies and migration probability under irradiation were derived. Effective works were introduced to the above processes as a result of the fission damage, and reduced activation energies for each process were defined. Based on the knowledge obtained in the transient state, the effective activation energies in the steady state were discussed. The above concepts were examined using the experiments of Clough.