An update of the state-of-the-art report on the corrosion of copper under expected conditions in a deep geologic repository

Copper has been the corrosion barrier of choice for the canister in the Swedish and Finnish, nuclear waste disposal programmes for over 30 years. During that time many studies have been carried out on the corrosion behaviour of copper under conditions likely to exist in an underground nuclear waste repository located in the Fenno-Scandian bedrock. This review is a summary of what has been learnt about the long-term behaviour of the corrosion barrier during this period and what the implications of this knowledge are for the predicted service life of the canisters. The review is based on the existing knowledge from various nuclear waste management programs around the world and from the open literature. Various areas are considered: the expected evolution of the geochemical and microbiological conditions in the groundwater and of the repository environment, the thermodynamics of copper corrosion, corrosion during the operational phase and in the bentonite prior to saturation of the buffer by groundwater, general and localised corrosion following saturation of the compacted bentonite buffer, stress corrosion cracking, radiation effects, the implications of corrosion on the service life of the canister, and areas for further study. This report is an updated version of that originally published in 2001/2002. The original material has been supplemented by information from studies carried out over the last decade. The conclusion drawn from this review is that the original prediction made in 1978 of canister lifetimes exceeding 100,000 years remains valid.