Modeling the high-T paramagnetic state of bulk UO2 by a non-spin-polarized calculation and neglecting the Hubbard-U correction for the f electrons in U atoms, the lattice thermal conductivity of bulk UO2 is investigated by the exact solution of the Boltzmann transport equation for the steady-state phonon distribution function. The results show that TA branches corresponding to U-atoms vibrations have the largest lifetimes and therefore have dominant role in thermal conductivity, while the optical branches corresponding mainly to O-atoms vibrations have the shortest lifetimes. Using this simple model, our results for the thermal conductivity show a very good agreement with the experiments. The calculations are repeated for bulk UO2 with different U-235 concentrations of 3\%, 5\%, 7\%, and 20\%, and the results show a small decrease of thermal conductivity which arise from scattering of phonons by impurities.
@article{arxiv.1907.04174,
title = {First-principles study of UO$_2$ lattice thermal-conductivity: A simple description},
author = {Samira Sheykhi and Mahmoud Payami},
journal= {arXiv preprint arXiv:1907.04174},
year = {2020}
}