Molecular dynamics simulations of fission gas xenon (Xe) diffusion at UO₂ grain-boundaries (Rev.1)

Technical Report · Wed Apr 05 00:00:00 EDT 2023

DOI:https://doi.org/10.2172/1969379· OSTI ID:1969379

Liu, Xiang-Yang  ^[1]; Galvin, Conor Oscar ^[1]; Cooper, Michael William Donald  ^[1]; Andersson, Anders David Ragnar  ^[1]

---

1. Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)

The diffusivity of fission gas xenon (Xe) at UO₂ grain-boundaries is one of the most important parameters in mechanistic modeling of fission gas diffusion in UO₂ based nuclear fuels. In this report, we use molecular dynamics simulations to investigate the Xe diffusivity in UO₂ grain-boundaries, employing the many-body potential developed by Cooper, Rushton and Grimes for UO₂. Three different types of grain-boundaries are investigated, twist Σ5, tilt Σ5, and a random grain-boundary. Diffusion activation energies in the range of 0.39 – 1.46 eV are obtained for the Xe diffusivity. Comparison to results for the uranium vacancy diffusivity from MD simulations employing the same methodology suggests a weak to moderate attractive Xe-uranium vacancy binding energy depending on the grain-boundary type.

• Research Organization: Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)
• Sponsoring Organization: USDOE Office of Nuclear Energy (NE); USDOE National Nuclear Security Administration (NNSA)
• DOE Contract Number: 89233218CNA000001
• OSTI ID: 1969379
• Report Number(s): LA-UR-22-28477; TRN: US2403337
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS