Molecular dynamics study of the bulk temperature effect on primary radiation damage in uranium dioxide

The effect of bulk temperature on the primary damage induced by a displacement cascade was investigated in uranium dioxide using classical molecular dynamics simulations. In this study, the Morelon potentials were used to model the middle-range interactions between the atoms that constitute the host matrix during the radiation events. Cascades were initiated by accelerating a uranium primary knock-on atom at 10 keV inside a perfect 1302 lattice at a temperature between 700 K and 1800 K, a range which comprises in-pile temperatures of oxide fuels in light water reactors in standard operating conditions. Cascade overlap sequences were also simulated at 700 K and 1400 K in,order to study the radiation damage accumulation in the oxide fuel. This study reveals the maximum damage level which the material can accommodate for decreases with the temperature. Furthermore the direct formation of vacancy clusters under irradiation is considerably slowed down above 1000 K, notably during cascade overlap sequences. (C) 2014 Elsevier B.V. All rights reserved.