THERMO-MECHANICAL PROPERTIES OF PuO_2, UO_2 AND U_(0.5)Pu_(0.5)O_2

摘要

For reactor design and safe operation, thermo-mechanical characteristics of nuclear fuel are of significant importance. In this study, the elastic properties of PuO_2, UO_2 and U_(0.5)Pu_(0.5)O_2 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)O_2 is similar to the linear interpolation between the EM of PuO_2 and UO_2, however, small deviation from linearity is observed at higher temperature in some cases. Comparison of temperature coefficients (€) of EM indicates that the isothermal values are more sensitive to temperature than the adiabatic counterparts. In addition, our results shows €_B > €_Y > €_G, where B, Y and G being the bulk, Young's and shear modulus respectively.