Corrosion processes and the expected evolution of the BSC-1 Supercontainer design for disposal of Belgian HLW and spent fuel

ONDRAF-NIRAS is evaluating the supercontainer concept for disposal of high-level waste (HLW) and spent fuel. In the supercontainer, a carbon steel overpack surrounds the HLW canisters or spent fuel assemblies. The overpack is surrounded by a concrete buffer, which creates a favourable alkaline geochemical environment. The buffer is enclosed by a stainless steel liner, which facilitates supercontainer construction and handling. The primary function of the overpack is to provide total containment of the radionuclides during the thermal phase. As part of the Supercontainer Project, a review was undertaken of corrosion processes and associated gas generation that might occur during the evolution of the supercontainer. This paper reports the main findings of the study, and focuses on the corrosion evolution of the overpack and liner.