Properties of recycled fuels; density functional theory study

The application of Density Functional Theory (DFT) approximation to assess the mechanical and structural properties of recycled urania and thoria fuel is presented. The calculated values of the lattice constant and mechanical moduli of ThO₂ and UO₂ are in good agreement with the experimental data. The calculations are further extended to study lattice constants of Pu-U oxides for which we do not have currently experimental data. The presented elastic moduli of ThO₂, UO₂ and Pu-U oxides are compared. The relative changes of the lattice constant of thoria and urania, calculated by first principles molecular dynamics as a function of temperature, agree with experiment. (author)