Modeling oxygen self-diffusion in UO2 under pressure

• Oxygen self-diffusion over a range of temperatures and pressures is important in UO2.
• The UO2 bulk modulus as a function of T and P is expressed in a single equation.
• The cBΩ model is used to derive the oxygen self-diffusion with respect to P in UO2.
• Advancing proliferation-resistant technologies to harvest the energy potential of spent fuel.

Access to values for oxygen self-diffusion over a range of temperatures and pressures in UO2 is important to nuclear fuel applications. Here, elastic and expansivity data are used in the framework of a thermodynamic model, the cBΩ model, to derive the oxygen self-diffusion coefficient in UO2 over a range of pressures (0–10 GPa) and temperatures (300–1900 K). The significant reduction in oxygen self-diffusion as a function of increasing hydrostatic pressure, and the associated increase in activation energy, is identified.