Thermo-Mechanical Properties of PuO<sub>2M/sub>, UO₂ and U_0.5Pu_0.5O₂

Abstract

For reactor design and safe operation, thermo-mechanical characteristics of nuclear fuel are of significant importance. In this study, the elastic properties of PuO₂, UO₂ and U_0.5Pu_0.5O₂ have been investigated in the temperature from 300 to 1500 K using Molecular Dynamics (MD) simulations. In general, the elastic properties decrease with the increase in temperature, which is commonly observed in other relevant studies. It is found that the adiabatic elastic constants (EC) and elastic modulus (EM) are higher than the respective isothermal values in all cases and the difference increases with the increase in temperature. At most temperatures, the elastic modulus (EM) of (U,Pu)O₂ is similar to the linear interpolation between the EM of PuO₂ and UO₂, however, small deviation from linearity is observed at higher temperature in some cases. Comparison of temperature coefficients (ϵ) of EM indicates that the isothermal values are more sensitive to temperature than the adiabatic counterparts. In addition, our results shows ϵ_B > ϵ_Y > ϵ_G, where B, Y and G being the bulk, Young’s and shear modulus respectively.