Molecular dynamics study on thermal properties of ThO2 doped with U and Pu in high temperature range

Molecular dynamic (MD) simulation has been performed to investigate the physical properties of ThO2 in the temperature range 300-3000 K. Using the three-point method, the parameters of Born-MayerHuggins potential with partially ionic model are obtained by fitting the lattice constants with experimental values. We predict that the melting point of ThO2 is 3650 +/- 10 K. Besides, the lattice parameter, linear thermal expansion coefficient and thermal conductivity of ThO2 are systematically evaluated in high temperature range. In order to validate the potential for description of the ThO2, it has been used to predict specific heat, bulk modulus and defect energy which are in good agreement with previous values. We further calculate the lattice parameters, thermal expansion and thermal conductivity of Th1-yUyO2 and Th1-yPuyO2. The calculated lattice parameters of mixed fuels closely follow the Vegard's law. With the improvement of the content y of doped U and Pu, thermal expansion coefficients both of them increase while the thermal conductivities decrease. The influence of Pu is more significant than U for thermal properties of ThO2. (C) 2014 Elsevier B.V. All rights reserved.