Hydrogen absorption associated with the corrosion mechanism of 316L stainless steels in primary medium of Pressurized Water Reactor (PWR)

Samples of 316L were exposed at 325 °C to PWR primary water labelled with deuterium and oxygen 18. The SIMS and GD-OES analysis has revealed the presence of deuterium in the internal oxide layer and in the underlying alloy. Two-stage corrosion experiments have shown that the oxygen and hydrogen transport in the oxide layer is not coupled and that the short-circuit diffusion coefficient of 18O in the oxide scale: Dsc = (9 ± 1)·10−17 cm2 s−1. These results are used to propose a mechanism describing the anionic growth of the protective oxide layer and the concomitant adsorption of hydrogen in the alloy.