Molecular dynamics simulation of displacement cascades in UO₂

CEA, DEC, SESC/LLCC, Bât. 352, 13108 Saint Paul Lez Durance Cedex, France

^* Corresponding Author, E-mail: guillaume.martin@cea.fr

Abstract

The primary damage induced within a uranium dioxide matrix subjected to a flux of energetic ions was investigated by classical molecular dynamics. UO₂ was modeled using the set of empirical potentials based on a rigid ion model. Displacement cascades were initiated by accelerating a uranium primary knock-on atom to a kinetic energy up to 100 keV. It was first shown that the estimated RID a-thermal coefficient is well below those which are deemed relevant for spent nuclear fuels. Cascades were then purposely overlapped within the same simulation box so as to study the response of the material to increasing damage levels. During cascade overlap sequences, the growth of nanometric voids was observed. Obtained results evidenced a radiation damage controlled heterogeneous mechanism for insoluble fission product segregation in UO₂.