| About this Abstract |
| Meeting |
2025 TMS Annual Meeting & Exhibition
|
| Symposium
|
Microstructural, Mechanical, and Chemical Behavior of Solid Nuclear Fuel and Fuel-Cladding Interface II
|
| Presentation Title |
Oxygen Potential and Uranium Diffusion in UO2±x: Density Functional Theory Calculations Including Spin-Orbit Coupling Effect and Dispersion Interactions |
| Author(s) |
William D. Neilson, Jason Rizk, Michael Cooper, David Andersson |
| On-Site Speaker (Planned) |
William D. Neilson |
| Abstract Scope |
At the root of many material properties is the concentration of point defects; they are highly influential on the behavior of UO2 across the fuel cycle—its fabrication, reactor performance, and disposal. We build a new thermodynamic defect model, informed by atomistic simulations, that enables quantitative investigation of UO2 defect chemistry over a wide range of conditions: experimental validation is achieved in the prediction of the oxygen potential and uranium self-diffusivity in UO2. The novelty here has been to employ density functional theory simulations that use large supercells, carefully avoid metastable defect structures, and consider spin orbit interactions, noncollinear magnetism, and a dispersion correction. Further, by considering the impact of thermal expansion—i.e. the impact of anharmonicity—we reveal a temperature dependence in the activation energy of uranium self-diffusion that is crucial to account for in order to describe high temperature U diffusivity measurements. |
| Proceedings Inclusion? |
Planned: |
| Keywords |
Ceramics, Modeling and Simulation, Nuclear Materials |