• Energy Research

Abstract A comprehensive molecular dynamics study was carried out to investigate the role of thorium and uranium contents on improving the thermal and mechanical properties of the Th1-xUxO2 nuclear fuels. In this regard, several thermophysical and mechanical properties of the Th1-xUxO2 solid solutions including the lattice parameter, density, thermal expansion coefficient, specific heat capacity, thermal conductivity, thermal diffusivity, linear (heat/power) rating, elastic constants (C11, C12, C44, bulk, shear, Young's moduli, and Poisson's ratio) and the maximum radial thermal stress applied to fuel pellets were numerically investigated in a wide range of temperature and compared with experimental results. The results indicated that the Th1-xUxO2 fuels have a lower density, specific heat capacity, and thermal expansion coefficient than pure UO2 at any temperature. The results also showed that the Th1-xUxO2 fuels could increase or decrease the thermal conductivity, thermal diffusivity, and the linear heat rating of nuclear fuels depending on the uranium content (x). The amount of x in which all of the mentioned parameters can rise calculated in a wide range of temperatures. Maximum radial thermal stress was another important parameter that explicated in this paper. Results demonstrated that the Th1-xUxO2 fuels have lower maximum radial thermal stress, especially at high temperatures. These improved the thermo-mechanical properties provide the possibility of rising the fuel burnup in the thorium-based fuels compared to the uranium-based fuels.

Abstract A comprehensive molecular dynamics study was carried out to investigate the role of thorium and uranium contents on improving the thermal and mechanical properties of the Th1-xUxO2 nuclear fuels. In this regard, several thermophysical and mechanical properties of the Th1-xUxO2 solid solutions including the lattice parameter, density, thermal expansion coefficient, specific heat capacity, thermal conductivity, thermal diffusivity, linear (heat/power) rating, elastic constants (C11, C12, C44, bulk, shear, Young's moduli, and Poisson's ratio) and the maximum radial thermal stress applied to fuel pellets were numerically investigated in a wide range of temperature and compared with experimental results. The results indicated that the Th1-xUxO2 fuels have a lower density, specific heat capacity, and thermal expansion coefficient than pure UO2 at any temperature. The results also showed that the Th1-xUxO2 fuels could increase or decrease the thermal conductivity, thermal diffusivity, and the linear heat rating of nuclear fuels depending on the uranium content (x). The amount of x in which all of the mentioned parameters can rise calculated in a wide range of temperatures. Maximum radial thermal stress was another important parameter that explicated in this paper. Results demonstrated that the Th1-xUxO2 fuels have lower maximum radial thermal stress, especially at high temperatures. These improved the thermo-mechanical properties provide the possibility of rising the fuel burnup in the thorium-based fuels compared to the uranium-based fuels.