Thermal conductivity of porous UO2: Molecular Dynamics study

Classical Molecular Dynamics (MD) was used to investigate the effect of nanometric size pores on the thermal conductivity of irradiated UO2. The Green-Kubo approach was used for the thermal conductivity calculation. The effects of pores size, porosity and pores separation were simulated. A comparison with existing theoretical models is presented and an analytical model adapted to irradiated fuel is obtained. The results demonstrate that, for realistic bubbles size and concentrations, the impact on the fuel thermal conductivity is higher than predicted by the correlations used to quantify the impact of porosity: the impact of 0.3 vol.% of nanometric pores is of the same order of magnitude as that of 4.5 vol.% of micrometric pores. (C) 2014 The Authors. Published by Elsevier B.V.