Effect of Temperature on the Crevice Corrosion Resistance of Ni-Cr-Mo Alloys as Engineered Barriers of Nuclear Repositories

AbstractDeep geological disposal is the strongest alternative to the disposal of high level nuclear waste. Alloys 625, C-22, C-22HS and HYBRID-BC1 are considered among candidates as engineered barriers of nuclear repositories. Localized corrosion, like crevice or pitting corrosion, is one of the most important degradation processes that will limit the lifetime of containers. The susceptibility to crevice corrosion is measured by the value of the repassivation potential (ECO). The objective of the present work is to assess the effect of temperature on the crevice corrosion resistance of these alloys.Alloy HYBRID-BC1 was the most resistant to chloride-induced crevice corrosion, followed by alloys C-22HS, C-22 and 625. ECO showed a linear decrease with temperature. There is a temperature above which ECO does not decrease anymore, reaching a minimum value. This ECO value is a strong parameter for assessing the localized corrosion susceptibility of a material in a long term timescale, since it is independent of temperature, chloride concentration, crevice mechanism, crevice gap and type of crevice formers