Describing oxygen self-diffusion in PuO2 by connecting point defect parameters with bulk properties
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The description of oxygen self-diffusion over a range of temperatures and pressures is important in PuO2 for nuclear fuel applications. Although there are limited experimental studies describing oxygen self-diffusion in PuO2, recent molecular dynamics studies extend the temperature range significantly. In the present study elastic and expansivity data is used in the framework of a thermodynamic model (known as the cBΩ model) to derive the oxygen self-diffusion coefficient in PuO2 in the temperature range 1800–3000 K. In the cBΩ model the defect Gibbs energy is proportional to the isothermal bulk modulus (B) and the mean volume per atom (Ω). The derived results are in good agreement with the most recent experimental and molecular dynamics data. Importantly, the present study extends the applicability of the model to nuclear fuel materials for the first time, where point defect parameters and behaviour are difficult to determine, particularly at the temperatures considered here.
KeywordsThO2 PuO2 Isothermal Bulk Modulus Superionic Transition Mixed Oxide Fuel
The authors thank Michael Cooper (Imperial College London) for continued informed discussions. This research was supported in part by the RCUK Energy Programme, and we are grateful to EPSRC for funding via the PROMINENT Nuclear Fission consortium grant. MEF is grateful for funding from the Lloyd’s Register Foundation, a charitable foundation helping to protect life and property by supporting engineering-related education, public engagement and the application of research.
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