| Abstract Scope |
This study aims to enhance the performance of light water reactor (LWR) fuel by exploring how dopants can improve the mechanical behavior of UO2 fuel pellets, particularly under accident scenarios. Specifically, the research focuses on mitigating pellet-cladding mechanical interactions (PCMI) by increasing the plasticity of the fuel. Certain dopants, such as chromium, are known to encourage grain growth, which in turn influences the microstructure and deformation mechanisms of the fuel.
A physics-based diffusional creep model, originally developed using lower-length-scale data, was refined in this work through Bayesian inference to better quantify the uncertainties associated with creep rate model predictions. The improved model provided calibrated data for integration into BISON, a fuel performance simulation code. In parallel, a new mechanistic crystal plasticity model was formulated to simulate dislocation glide and climb, which are dominant under high-stress conditions. This is particularly relevant for doped UO2.
Results show that increased grain size due to doping enhances deformation rates within the glide regime, suggesting potential benefits for reducing PCMI. Collectively, these efforts contribute to a more detailed and physics-informed approach for incorporating deformation behavior into nuclear fuel performance modeling. |