Grain Boundary Oxidation of Neutron Irradiated Stainless Steels in Simulated PWR Water

Characterization of IASCC crack tips extracted from neutron-irradiated flux thimble tube specimens in view of a probabilistic fracture model

“…At low levels of applied macroscopic stress, oxidation in front of the crack tips remains moderately comparable to known literature data [43]. Under these conditions, the oxidation is mainly determined by the effects of the high neutron-irradiation doses [37,36] and prior cold-work treatment [38], both having shown to increase the oxidation rates in laboratory experiments. However, as the applied macroscopic stress increases, an effective increase in mean oxidation length in front of the crack tips can be observed.…”

“…On par with the increased oxidation at one of the two neighboring grains, these oxide intrusions appeared to be correlated with strong deformation fields adjacent to the crack front near the grain boundary. It is reasonable that the lattice deformation and the local dislocation activity at the crack tip facilitated the intergranular oxidation, in addition to the known enhancing effects caused by the irradiated neutron-dose [36,37] and applied levels of cold-work [38]. Observations of these oxide intrusions trigger a redefinition of what is implied by an intergranular crack tip; that is, it being referred to as the cracked oxide or the end of the oxide intrusion observed in the leading grain boundary.…”

“…This variation could be reasoned in terms of varying material and testing conditions, exposure times to the corrosive environment, and due to the effective stress concentration at the crack tip. It is further assumed that the high irradiated doses of the flux thimble tube material (60 − 80 dpa) and its applied level of cold-work (20% CW) have significant impacts on the oxidation rates at the IASCC crack tip [37,36,38]. Observations of these crack tips have also indicated towards microstructural features that are considered as evidence of fast-diffusion paths for oxygen species [51].…”

Review on synergistic damage effect of irradiation and corrosion on reactor structural alloys

“…For a given material, the irradiation-induced defect density and/or size increases with increasing irradiation dose (Fig. 5b) or elevated irradiation temperature [20,74,86]. Consequently, the diffusion rates of the metal cations and oxygen anions increase, resulting in an elevated oxidation rate.…”

“…Generally, these irradiation-induced defects accelerate corrosion primarily in two ways [19,20,74,83,[85][86][87][88][89]:…”