Behavior of Fission Gas Release with Valance Effect in irradiated UO2

Fission gas release is one of the most important behaviors in fuel performance, which is related to the fuel temperature and the internal pressure. The diffusion coefficient of fission gas is a fundamental parameter to establish a diffusion equation. This was obtained by the post-irradiation annealing test, which is a basic system to observe several diffusion mechanisms with a multiple steps as the sample preparation conditions. Generally, the diffusion coefficient is affected by temperature, stoichiometry, the irradiation effect, and the valence of fission products. In this study, the PIA test(post-irradiation annealing test) with UO2 + additives(+3, +4, +5 valence) was carried out to observe the valence effect