Further studies on the anaerobic corrosion of carbon steel in alkaline media in support of the Belgian supercontainer concept

Abstract In the Belgian supercontainer concept, a carbon steel overpack surrounds high‐level radioactive waste and spent fuel containers and is encased in a cementitious buffer material. Research has been carried out to characterise the anaerobic corrosion of carbon steel in an anoxic artificial alkaline porewater that simulates the cementitious buffer material and also in solid cement matrices, in the presence of chloride and the sulphur species expected in the groundwater. The current study focuses on recent results. Specifically, it provides an update on the long‐term corrosion rates obtained from gas generation measurements (including new data from higher‐sensitivity autoclaves) and weight loss measurements and provides results of postmortem analysis of dismantled cells. The behaviour of the system is discussed, focusing on the effects of the solution chemistry, precorrosion treatments and γ radiation on corrosion rates, the electrochemical response of the steel when irradiated, and the morphology of the corrosion product. The corrosion rate was lower in cement than in an aqueous system. Radiation affected the corrosion potential and the morphology of the corrosion product.