Copper has, based on its favorable corrosion properties according to established scientific knowledge, been selected as a container material in the KBS-3 repository concept. The view that copper corrodes only to a very limited extent in pure O2-free water has, however, been challenged in some publications during the last decade. Therefore, SKB has initiated experimental and theoretical work to evaluate the claims made in those publications.

The experiments on which the claims are based have been repeated under more controlled conditions and an alternative method to carry out the same measurement has been developed and applied. No evidence of continuing copper corrosion was found. Theoretical and experimental work has been carried out in search of hitherto unknown species of the Cu-O-H system that could be a driving force for corrosion reactions. No such species were found. Reports of these works are summarized and it is concluded that the scientific basis for claiming that copper corrodes in pure water to an extent exceeding that predicted by established thermodynamic data is weak.

In addition, “what if” calculations are presented, where it is hypothetically assumed that the recent claims regarding copper corrosion are correct. The calculations demonstrate that copper corrosion depths in a final repository would be of the order of 1 mm in one million years, also for a bounding case where no transport limitations in a repository environment are taken into account.