Development of the advanced mechanistic fuel performance and safety code using the multi-scale approach

The SFPR code designed for mechanistic modeling of single fuel rod behavior under various regimes of LWR reactor operation (normal and off-normal, including severe accidents), is under development at IBRAE during the last two decades and currently, being extended to Fast Reactors, serves as a prototype for a new mechanistic fuel performance code BERKUT. The SFPR meso-scale models include an extended set of microscopic parameters, characterizing the crystal defect structure, thermo-physical and thermo-chemical properties of irradiated fuel. Increasing computational capabilities and rapid development of effective interatomic potentials allow micro-scale representations of the materials and physics to inform - via meso-scale code - the macro-level simulation. The first examples of atomistic calculations (by molecular dynamics and Monte-Carlo methods) of the key microscopic parameters for input in SFPR and BERKUT, validation of the modified code and application of the 3D finite element method for improvement and verification of the 1D thermo-mechanical model, are presented.