Toward an Atomistically Informed Fuel Performance Code: Thermal Properties Using FRAPCON and Molecular Dynamics Simulation

A proof-of-principle study is presented in which the results of atomic-level simulations of the thermal expansion and thermal conductivity of UO₂ are integrated into the fuel performance code FRAPCON. The beginning-of-life (BOL) thermal conductivity profile of a fuel pellet and the evolution of the pellet expansion over its lifetime are determined. It is found that (a) modifying FRAPCON to accept input from atomistic simulations (or elsewhere, such as new experiments or other calculations) is relatively straightforward, at least for these two properties, and (b) the properties determined from atomistic simulations yield predictions in FRAPCON that are in good agreement for the BOL thermal conductivity, but much less satisfactory for the pellet expansion.