Irradiation-induced heterogeneous nucleation in uranium dioxide

Using classical molecular dynamics simulations, we have studied the first stages of defect cluster formation resulting from 10 keV displacement cascades in uranium dioxide. Nanometre size cavities and dislocation loops are shown to appear as a result of the irradiation process. A specifically designed TEM experiment involving He implanted thin foils have also been carried out to support this modelling work. These results, in conjunction with several other observations taken from the literature of ion implanted or neutron irradiated uranium dioxide, suggest a radiation damage controlled heterogeneous mechanism for insoluble fission product segregation in UO₂.