Network percolation using a two-species included phase model to predict fission gas accommodation and venting

The Included Phase Model (IPM) is a mesoscale technique, which describes the morphology of phase-phase interfaces as a parametric surface to reduce computational costs while preserving the important features of phase-field type models. The IPM is extended to include a fluid species (fission gas) occupying vacancies. System evolution is driven by interfacial energy, elasticity of the surrounding matrix, and internal energy of the fluid. The model is extended to multiple grains using a symmetry condition and applied to a network of hexagonal grains. The model is applied to investigate fission gas accommodation and percolation as a function of the distance to a free surface and distribution of high fission density areas corresponding to heterogeneity resulting from the manufacturing processes of mixed oxide fuels.