Crystal Plasticity Modelling of Neutron Irradiation Effects on the Flow and Damage Behaviour of Zircaloy-4

Zircaloy-4 is an alloy of zirconium used to make the cladding of nuclear fuel tubes in reactors. The cladding is subjected to neutron irradiation during its service inside the nuclear reactor that leads to degradation of its mechanical properties. In this work, the irradiation hardening and softening of the polycrystalline Zircaloy-4 under various doses of neutron irradiation are simulated using a crystal plasticity finite element model (CPFEM). The crystal plasticity model is based on dislocation density and defect (produced during irradiation) density-based kinetics of plastic deformation in crystals. An increase in yield stress due to irradiation is modelled by considering the defect density produced by irradiation. The defect density evolution models the loss in ductility occurring to the irradiated materials due to the formation of defect-free channels with plastic straining. The model parameters are obtained by fitting the simulation against experimental data from the literature.