Structure characterization and steam oxidation performance of U3Si2 with Zr alloying additions

Abstract

Research and development of high uranium density fuels supports the on-going effort to enhance reactor technology, safety, performance, and economics. Among high uranium density fuels, U3Si2 is a favored fuel candidate due to its higher uranium density and improved thermal conductivity when compared to traditional UO2. While U3Si2 demonstrates an improved fuel economy, it suffers from rapid degradation when exposed to water at T > 300°C. In order for U3Si2 to be implemented in water cooled reactors, the water reaction must be understood and mitigated. Reported here is the performance of Zr alloying additions to U3Si2 exposed to high temperature steam oxidation environments. The investigation shows that homogenization heat treatment contributes to a delayed onset of oxidation and an improved homogeneity throughout the arc-melt fabricated alloyed compositions. Of the pre- and post-annealed samples, the post-annealed 7 vol% Zr addition exhibited the highest onset temperature of oxidation. A preliminary computational investigation to complement the experimental analysis assesses the solubility of Zr in U3Si2 and its incorporation in the crystal lattice.