Atomic simulations of primary irradiation damage in U–Mo–Xe system

Abstract

To shed a light on Xe bubble nucleation in U–Mo fuel from the view of primary irradiation damage, a reported U–Mo–Xe potential under the framework of embedded atom method has been modified within the range of short and intermediate atomic distance. The modified potential can better describe the interactions between energetic particles, and can accurately reproduce the threshold displacement energy surface calculated by the first-principles method. Then, molecular dynamics simulations of primary irradiation damage in U–Mo–Xe system have been conducted under different contents. The raise of Xe concentration brings about a remarkable promotion in residual defect quantity and generates bubbles in more over-pressured state, which suggests an acceleration of irradiation damage under the accumulation of the fission gas. Meanwhile, the addition of Mo considerably reduces the residual defect count and hinders irradiation-induced Xe diffusion especially at high contents of Xe, corroborating the importance of high Mo content in mitigation of irradiation damage and swelling behavior in U–Mo fuel. In particular, the variation of irradiation damage with respect to contents suggests a necessity of taking into account the influence of local components on defect evolution in mesoscale simulations.