Interaction between 1/2 110 001 dislocations and 110 prismatic loops in uranium dioxide: Implications for strain-hardening under irradiation

M Borde and L Dupuy and A Pivano and B Michel and D Rodney and J Amodeo, INTERNATIONAL JOURNAL OF PLASTICITY, 168, 103702 (2023).

DOI: 10.1016/j.ijplas.2023.103702

Plasticity of irradiated UO2 is of major interest to improve the risk assessment of the nuclear fuel cladding failure in the case of design basis accidents. In this study, we investigate the main irradiation- hardening processes induced by 110 irradiation loops interacting with glissile dislocations of the primary slip system, 1/2<110>001, of UO2. The interactions are simulated at two scales using molecular dynamics and discrete dislocation dynamics, to characterise local interactions and identify strengthening configurations as a function of the dislocation-irradiation loop geometry. In particular, we show that 1/2<110>001 screw dislocations can be strongly pinned by helical turn configurations. Statistical large-scale discrete dislocation simulations are performed to investigate the collective behaviour of a large density of irradiation defects and quantify irradiation hardening. Several microstructural processes including loop drag and shovelling are observed and their involvement in clear band formation and hardening of UO2 fuel at high temperature is discussed.

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