Fission gas diffusion and release for Cr<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si1.svg"><mml:msub><mml:mrow /><mml:mn>2</mml:mn></mml:msub></mml:math>O<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si11.svg"><mml:msub><mml:mrow /><mml:mn>3</mml:mn></mml:msub></mml:math>-doped UO<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si1.svg"><mml:msub><mml:mrow /><mml:mn>2</mml:mn></mml:msub></mml:math>: From the atomic to the engineering …

The anticipated benefits of large grains in Cr2O3-doped UO2 pellets include improved mechanical and fission gas retention properties. To support the assessment release (FGR) from doped pellets, impact doping on diffusivity for in-reactor conditions must be understood. In this work, we tackle issue by informing model within BISON fuel performance code using material models developed at atomic scale. investigation intra-granular is carried out adapting a cluster dynamics that, accounting thermochemistry, capable describing Xe diffusion under irradiation undoped as starting point. Using thermodynamic analysis, it shown that stoichiometric with additions Cr2O3, oxygen potential defined Cr-Cr2O3 two-phase equilibrium. model, predicted was significantly increased both intrinsic irradiation-enhanced regimes compared to UO2, result higher concentrations uranium vacancies, respectively. This consequence more oxidizing high temperature, reducing low doping. Arrhenius functions have been fitted results enable implementation new diffusivities behavior model. simulations were out, showing competing effects enlarged which act suppress enhance release, physics-informed validated against experimental measurements normal operation. Additionally, benchmarking power ramp conditions. agreed well data, noticeable improvements over standard