Impact of γ-radiation on carbon steel anaerobic corrosion and H2 production.

Stavroula Isidora Giannakandropoulou (1, 2, 3) , Hortense Desjonqueres (1) , Charles Wittebroodt (4) , Gérard Baldacchino (2, 3)

1 IRSN/PSN-RES/SCA/LECEV - Laboratoire d'expérimentations sur le comportement des équipements et la ventilation
2 LIDYL - Laboratoire Interactions, Dynamiques et Lasers (ex SPAM)
3 DICO - Dynamique et Interactions en phase Condensée
4 IRSN/PSE-ENV/SPDR/LETIS - Laboratoire d'étude et de recherche sur les transferts et les interactions dans les sous-sols

This article reports investigations on the anoxic corrosion process impacting a carbon steel/ultrapure deaerated water system when it is exposed to gamma radiation (50 Gy h$^{-1}$), and on the associated molecular hydrogen gas generation. On the one hand, a dynamic semi-open experimental setup allowing to distinguish between the H$_2$ production related to water radiolysis and the one related to anoxic corrosion has been adopted to estimate the corrosion rate associated to three successive temporal phases: pre-irradiation, irradiation and post-irradiation phases. On the other hand, post mortem analyses performed on both liquid and solid samples permitted to (i) quantify the chemical changes occurring in solution due to the formation of water radiolysis products and (ii) observe and characterize the thin corrosion layer composed of magnetite (Fe$_3$O$_4$) at the surface of the metallic coupons. We show that gamma radiation induces a slight diminution of the carbon steel corrosion rate. However, by comparing the mean corrosion rate values obtained for the three studied phases (i.e., before, during and after irradiation), the chemical changes caused by radiolytic species seem to inhibit the formation of a thick magnetite protective layer. Additionally, the corrosion rate observed in post-irradiation phase does not decrease over time, which suggests that irradiation could modify the properties of the corrosion product layer by making it less protective. A structural modification of this oxide film might be caused by the oxidizing water radiolysis products. Such mechanisms may favour continuous active corrosion processes rather than passivation of the metallic surface and thus lead to a reduced lifetime of the component.

Mots clés: Anoxic corrosion; carbon steel; water radiolysis; γ-rays; hydrogen production

Domaines: Sciences de l'environnement; Chimie

Stavroula Isidora Giannakandropoulou, Hortense Desjonqueres, Charles Wittebroodt, Gérard Baldacchino. Impact of γ-radiation on carbon steel anaerobic corrosion and H2 production.. Radiation Physics and Chemistry, 2023, 206, pp.110742. ⟨10.1016/j.radphyschem.2022.110742⟩. ⟨hal-03909667v2⟩