Molecular dynamical study of physical properties of (U0.75Pu0.25)O2−x

Physical properties of mixed-oxide fuel (U0.75Pu0.25)O2−x (x=0.0,0.02,0.06,0.1,0.15,0.2,0.25) have been investigated by the molecular dynamic (MD) simulation in the temperature range 300-3000 K. The lattice parameter, linear thermal expansion coefficient, compressibility, bulk modulus and thermal conductivity are systematically investigated and analyzed by comparison with experiments and previous calculations. The calculated results of physical property are in good agreement with the experimental values and literature data. The oxygen vacancies have a significant effect on thermal properties of MOX. As oxygen vacancies increase, the bulk modulus gradually tend to be linear relationship with temperature and the thermal conductivity decreases very clearly, also, the temperature dependence weakens. In addition, we found that the influence of plutonium concentration for thermal conductivity is so small that it can be ignored when oxygen vacancies are existent.