Helium Irradiation Effect on Hydrogen Isotope Permeation in Austenitic Stainless Steel

Abstract

Pre- and simultaneous-irradiation effects on the D permeability of Type-316 stainless steel were investigated using a dual ion-beam irradiation facility. In the He pre-irradiation experiment, the relative D permeation rate decreased to about 0.3 under backward He ++ irradiation and increased to about 3 under forward He + irradiation for a He fluence higher than 2×10 17 He/cm 2 . By a numerical analysis, the change in the permeation rate was found to be mainly attributable to a diffusion-constant reduction in the He-implanted region. In a simultaneous D + and backward He ++ irradiation experiment, a rapid D permeation rate change occured, probably due to an instantaneously induced D diffusion barrier in addition to the gradual change of the premeation rate similar to that shown in the He backward pre-irradiation experiment.