Fission Gas Diffusion and Release for Cr 2 O 3 -Doped UO 2: From the Atomic to the Engineering Scale
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1875791.pdf
Description
Accepted version
Size
1.47 MB
Format
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Checksum (MD5)
a2f2be54f989d999b1311b4235d09866
Author(s)
Cooper, Michael WD
Pastore, Giovanni
Che, Yifeng
Matthews, Christopher
Forslund, Axel
Stanek, Christopher R
Shirvan, Koroush
Tverberg, Terje
Gamble, Kyle A
Mays, Brian
Date Issued
2021
Journal
Journal of Nuclear Materials
Publisher
Elsevier BV
Citation
Cooper, Michael WD, Pastore, Giovanni, Che, Yifeng, Matthews, Christopher, Forslund, Axel et al. 2021. "Fission Gas Diffusion and Release for Cr 2 O 3 -Doped UO 2: From the Atomic to the Engineering Scale." Journal of Nuclear Materials, 545.
Version
Author's final manuscript
Abstract
© 2020 The anticipated benefits of large grains in Cr2O3-doped UO2 pellets include improved mechanical and fission gas retention properties. To support the assessment of fission gas release (FGR) from doped pellets, the impact of doping on fission gas diffusivity for in-reactor conditions must be understood. In this work, we tackle this issue by informing the fission gas model within the BISON fuel performance code using material models developed at the atomic scale. The investigation of intra-granular fission gas diffusivity in Cr2O3-doped UO2 is carried out by adapting a cluster dynamics model that, accounting for UO2 thermochemistry, is capable of describing Xe diffusion under irradiation in undoped UO2 as the starting point. Using a thermodynamic analysis, it is shown that in stoichiometric UO2 with additions of Cr2O3, the oxygen potential is defined by the Cr-Cr2O3 two-phase equilibrium. Using the cluster dynamics model, the predicted Xe diffusivity in doped UO2 was significantly increased in both the intrinsic and irradiation-enhanced regimes compared to undoped UO2, as a result of higher concentrations of uranium and oxygen vacancies, respectively. This is a consequence of the more oxidizing conditions at high temperature, and more reducing conditions at low temperature, as a result of doping. Arrhenius functions have been fitted to the cluster dynamics results to enable implementation of the new diffusivities in the BISON fission gas behavior model. BISON simulations were carried out, showing the competing effects of the enlarged grains and the new fission gas diffusivity model, which act to suppress and enhance fission gas release, respectively. The new physics-informed model was validated against in-reactor experimental measurements under normal operation. Additionally, benchmarking was carried out for power ramp conditions. The predicted fission gas release agreed well with the experimental data, showing noticeable improvements over the standard UO2 model.
MIT Department
Massachusetts Institute of Technology. Department of Nuclear Science and Engineering
Terms of Use
Creative Commons Attribution-NonCommercial-NoDerivs License
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DOI of Published Version
https://doi.org/10.1016/J.JNUCMAT.2020.152590
