| Abstract Scope |
It is well-established that for UO2 fuels, the fission gas release rate and probability of fuel fragmentation rapidly increase at high burnup (HBU), particularly during thermal transients associated with Design basis accidents (DBAs). By combining multiphysics and multiscale modeling techniques, we investigate the irradiation-induced co-evolution of microstructure and thermo-mechanical properties of UO2 fuels at operating and accident-like conditions. Specifically, we utilize spatially-resolved rate-theory to simulate irradiation effects, phase-field to model microstructure evolution, and finite-element to predict thermo-mechanical properties of high burnup fuels. Moreover, we construct a simple one-way coupling approach that incorporates the effects of irradiation-induced microstructure evolution and micro-cracking into pellet-scale fuel performance simulations. The predictions of the models give new insights into the restructuring, micro-cracking, fragmentation, and gas release processes. |