Radiation-Enhanced Diffusion of U, Mo and Xe in γU-10Mo Alloy

Low enriched uranium (LEU) (&lt; 20 wt.% ²³⁵U)-molybdenum (U-Mo) monolithic fuel is the primary candidate for the fuel conversion in high performance research and test reactors. The LEU fuel is in the process of being qualified to replace the highly-enriched uranium fuel. As part of the qualification process, it is critical to understand and predict behavior of fission gas bubbles under irradiation, which contributes to fuel swelling, and potentially fuel failure. Mechanistic fuel models are currently being developed that can both reproduce the existing experimental data on fuel swelling, and be further applied to irradiation conditions beyond the experimental parameters. Diffusion of species under irradiation conditions is an important parameter in the mechanistic fuel models, however no temperature-relevant experimental diffusion data exists. In the present work, radiation-enhanced diffusion coefficients of U, Mo, and Xe in <b>γ</b>U-10wt.%Mo will be calculated in the temperature range between 300 K and 1400 K via rate-theory models and molecular dynamics simulations with an embedded-atom method interatomic potential for the U-Mo-Xe system. Accordingly, total diffusion coefficients under relevant irradiation conditions will be presented using previously calculated intrinsic thermal diffusion and radiation-driven diffusion.