Corrosion issues of carbon steel radioactive waste packages exposed to cementitious materials with respect to the Belgian supercontainer concept

The supercontainer is the reference concept for the post-conditioning of vitrified high-level radioactive waste and spent fuel in Belgium. It comprises a prefabricated concrete buffer that completely surrounds a carbon steel overpack. In this highly alkaline environment (pH ∼13.6) and under normal conditions (i.e. without the ingress of aggressive species), the carbon steel overpack will be protected by a passive oxide film, which is expected to result in very low uniform corrosion rates. Considering the long timescales applicable to waste disposal, determining accurate and reliable estimates of the uniform corrosion rate under anoxic conditions forms a very important part of the safety and feasibility strategy. On the other hand, the occurrence of localised forms of corrosion cannot be neglected and, therefore, it is also crucial to demonstrate that no other form of corrosion apart from uniform corrosion can take place. This paper gives an overview of the status of the research into the uniform corrosion, pitting corrosion and stress corrosion cracking behaviour of P355 QL2 grade carbon steel exposed to an artificial concrete pore water solution.This paper is part of a supplement on the 6th International Workshop on Long-Term Prediction of Corrosion Damage in Nuclear Waste Systems.