Damien Féron

A global transition towards more sustainable, affordable and reliable energy systems is being stimulated by the Paris Agreement and the United Nation's 2030 Agenda for Sustainable Development. This poses a challenge for the corrosion industry, as building climate‐resilient energy systems and infrastructures brings with it a long‐term direction, so as a result the long‐term behaviour of structural materials (mainly metals and alloys) becomes a major prospect. With this in mind “Corrosion Challenges Towards a Sustainable Society” presents a series of cases showing the importance of corrosion protection of metals and alloys in the development of energy production to further understand the science of corrosion, and bring the need for research and the consequences of corrosion into public and political focus. This includes emphasis on the limitation of greenhouse gas emissions, on the lifetime of infrastructures, implants, cultural heritage artefacts, and a variety of other topics.

We present a stochastic three‐dimensional cellular automata model of aqueous corrosion. We consider the cathodic reaction with dissolved oxygen and different concentrations of the oxidizer. We study the role and the stability of the passive layer and its effect on the kinetics, surface morphology, and roughness of the metallic surface. The model considers balanced spatially separated anodic and cathodic reactions and is capable of illustrating the cathodic control of the corrosion rate. Besides the electrochemical reactions, we take into account ionic diffusion, and acidic/basic neutralization. Results are compared to the aqueous corrosion of Fe in a near‐neutral solution.

This paper focus on the corrosion behaviour of austenitic 316L stainless steel in PWR primary water under the influence of radiolysis, including experimental devices and main obtained results. After a short overview of the literature in the field, the approach is described with the use of a high energy proton beam to control the production of radiolytic species at the interface between stainless steel (316L type) and PWR water solution in a high temperature and high pressure electrochemical cell working up to 300°C and 100 bar. The corrosion potential of stainless steel was enhanced by the radiolysis causing by high energy proton beam. A high similarity of electrochemical behaviour was also observed under electron beam. The electrochemical oxidative response of the 316L/PWR solution interface under radiolysis is related to the surface characterization analysis (SEM, XPS, Raman spectroscopy, NRA...) on the oxide layers of 316L which are formed under or without irradiation. The radiolysis effect on the oxide film includes micron scale cavities which were observed in a highly irradiated oxide film. The observation of a-Fe₂O₃ hematite on the outer oxide film where cavities were formed is in accordance with the electrochemical oxidative response. Radiolysis influences not only the electrochemical behaviour but also the oxide formation of stainless steel in high temperature water environments, like primary water of Pressurised Water Reactors (PWR).

Historical views on stress corrosion cracking (SCC) of nickel-based alloys in light water nuclear power plants include the first cracks observed on Alloy 600 in pure water at 350°C by Henri Coriou in 1959. Extensive progress in the understanding of SCC of nickel-based alloys is underlined with the quantitative micro-nano approach proposed by Roger Staehle: atomistic and molecular simulations together with crack observations and dedicated experiments using tracers (deuterium and oxygen 18) lead to an intergranular oxidation mechanism with a possible influence of hydrogen.

Matériaux & Techniques, la revue des matériaux industriels et de leurs techniques de mise en oeuvre

(2017). Editorial for the special issue on Corrosion of Nuclear Materials. Corrosion Engineering, Science and Technology: Vol. 52, Corrosion of Nuclear Materials, pp. 557-557.

Stress corrosion cracking of P235 and P265 steels is investigated through slow strain rate and constant deformation tests on samples exposed in a cell reproducing the underground conditions of the French deep geological nuclear disposal, at 25 and 90°C. The samples were taken from the base metal, the heat affected zone and the fusion zone of a P265 steel weld joint. Tests were performed at the free corrosion potential and under polarisation in the cathodic or anodic domains. Long-term constant deformation tests were also carried out to evaluate the behaviour of the material under static loading in hydrated clay environment. The results show a significant sensitivity of the tested materials to environmental cracking in the experimental conditions, with an enhancement of the effect of the environment for the weld metal. A mechanism of hydrogen embrittlement is proposed to be responsible for the cracking phenomenon. Susceptibility to environmental assisted cracking observed during these tests indicates the need to optimise welding parameters and steel chemical composition and metallurgy, particularly regarding the presence of inclusions in the base metal and stress relief of the weld metal. This paper is part of a supplement on the 6th International Workshop on Long-Term Prediction of Corrosion Damage in Nuclear Waste Systems.