Michael Welland1

1, Canadian Nuclear Laboratories, Chalk River, Ontario, Canada

As interest in the microstructural evolution of nuclear fuels increases, there is motivation to develop computationally efficient mesoscale models consistent with CALPHAD treatments to understand these processes. This work describes development of multiphysics phase-field models which incorporate thermodynamic potentials as driving forces for transport phenomena and phase evolution while controlling implicit interfacial energy contributions. The model is discussed with examples of overpressurised intragranular fission gas bubble migration, and multiphase Al-Mg interdiffusion for advanced research reactor fuel.
Also discussed is the newly developed Included Phase model applied to intergranular fission gas bubble coalescence and percolation on the grain boundary network. This model achieves a substantial reduction in computational expense by solving the 3D phenomenon using a 2D model embedded in 3D space using a projection technique.