Synergy of electronic and nuclear energy depositions on the kinetics of extended defects formation in UO2, based on in situ TEM observations of ion-irradiation-induced microstructure evolution

During in reactor operations, the slowing down of fission fragments generates most radiation damage uranium dioxide. Fission deposit their energy to both atomic and electronic subsystems through nuclear interactions. To study possible synergistic effects deposition on microstructure, UO2 thin foils have been irradiated with 0.39 MeV Xe and/or 6 Si ions at 298 K using single or dual beam ion irradiations. The evolution extended defects was characterized by situ Transmission Electron Microscopy. Results show a similar fluence increase, irrespective beam: nucleation small dislocation loop that increase density up saturation value, followed an average size. However, kinetics differs according irradiation conditions. In case irradiation, all phenomena occur lower value level. local temperature along path seems lead enhanced defect mobility, as irradiations performed higher temperatures.