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

• Published in: Journal of nuclear materials Vol. 554; p. 153088
• Main Authors: Bricout, M., Gutierrez, G., Baumier, C., Bachelet, C., Drouan, D., Garrido, F., Onofri, C.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.10.2021; Elsevier BV
• Subjects: Defects; Dislocation loops; Dual ion beam irradiation; Evolution; Extended defects; Fluence; Foils; Fragments; In situ TEM; Ion beams; Irradiation; Kinetics; Microstructure; Nuclear energy; Nuclear reactors; Nucleation; Radiation; Radiation damage; Subsystems; Synergistic effect; Transmission electron microscopy; UO2; Uranium; Uranium dioxide; UO2; Dual ion beam irradiation; In situ TEM; Extended defects
• ISSN: 0022-3115; 1873-4820
• DOI: 10.1016/j.jnucmat.2021.153088

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