Hydrogen concentration and hydrides in Zircaloy-4 during cyclic thermomechanical loading

Synergistic coupling of thermomechanical loading and irradiation damage in Zircaloy-4

“…where τ i 0 is the intrinsic material CRSS (measured experimentally [22]), µ is shear modulus, ρ SSD is the density of statistically stored dislocations (SSDs), whose evolution is linear with plastic strain [23], ρ GND is the density of geometrically necessary dislocations (GNDs) [24], and ρ loop is the total density of dislocation loops, which form during irradiation. Temperaturedependant elastic-plastic properties [23] are also incorporated. SSD density evolution is controlled by ρ SSD = γ st p, where p is cumulative plastic strain and γ st is a material constant.…”

“…Plane strain boundary conditions are imposed in each case, which are representative of a pipe. Figure 5 (b) shows the thermomechanical loading conditions applied to the sub-model; three repeating thermomechanical cycles [23] are used to study cyclic plasticity. One case of irradiation damage evolution up to 6 dpa is also presented in the figure, which shows the synergistic coupling of damage and thermomechanical loading.…”

“…Thermomechanical loads are applied to unirradiated material and hence, ρ loop = dρ loop dt = 0 throughout. Thermomechanical cycles used for each simulation from Liu et al [23]. The selected maximum internal pressure is increased at the beginning of each cycle, held constant, and decreased, while there are two separate dwell periods for temperature.…”

“…For demonstration purposes, a large dose rate is selected to reach 6 dpa within just a few cycles. Reprinted from [23], Copyright (2021), with permission from Elsevier.…”