1. A phase field fracture model developed in MARMOT and parameterized with molecular dynamics results was used to identify the impact of GB bubbles on the fracture stress in UO2 fuel.
2. Grain size evolution in fuels materials impacts thermal conductivity, creep, swelling, and fission gas release. We evaluated driving forces and resistive pressures affecting grain boundary motion using mesoscale models parameterized by lower lengthscale simulations


3. Thermal conductivity of UO2 degrades during service, impacted by the microstructure features developed including dispersed lattice defects and impurities, fission gas bubbles, and interfaces. Development in MARMOT has enabled representation of the evolution of various microstructure features and calculations of the consequent thermal conductivity. MARMOT simulations have been successfully used to develop analytical models for evolving thermal conductivity during fuel operation, to be used in BISON.