Investigating constituent redistribution in U-Zr metallic fuels: A phase-field approach incorporating porosity and sodium infiltration

Abstract

U-Zr metallic fuel, known for its superior thermal conductivity compared to ${\text{UO}}_2$ fuel, is a promising candidate for advanced nuclear reactors. However, redistribution of constituents during operation affects the integrity of the fuel and phase stability, necessitating detailed investigation. In this study, a phase-field model was developed using the Multiphysics Object-Oriented Simulation Environment (MOOSE) to analyze the effects of porosity and sodium infiltration on redistribution behavior. A Baseline model incorporating a phase dependent porosity model was established, enabling comparative analyses. For instance, without considering porosity, our simulation resulted in an approximate 0.17 at% decrease in the central Zr concentration and a 36 K decrease in centerline temperature. Considering 50% sodium infiltration lead to a 0.7 at% lower central Zr concentration and an approximately 20 K decrease at centerline temperature. The findings demonstrate the importance of accurately modeling thermal conductivity to predict fuel behavior, providing a basis for optimizing U-Zr fuel performance in advanced reactor applications.