Understanding of the corrosion processes of a copper used fuel container

Full text of publication follows: Conceptual designs of copper containers for long-term containment and isolation of used nuclear fuel in deep geological repositories in crystalline rock and in sedimentary rock have been developed in Canada. The conceptual designs, with a capacity of over 300 used Candu fuel bundles, comprises a carbon steel support vessel and an outer corrosion barrier made of oxygen-free phosphorus-doped (OFP) copper. Extensive experimental and modelling programs have been carried out on the corrosion of copper used fuel containers over the past 20 years. Experimental studies have focused on uniform corrosion, microbiologically influenced corrosion (MIC) and stress corrosion cracking (SCC). Modelling studies have addressed uniform and localized (pitting) corrosion, SCC, MIC, and predictions of the evolution of environmental conditions within a deep geological repository. Results obtained to-date support the safe containment and isolation of used fuel in copper used fuel containers for a substantial period (≥ 100,000 years) in a deep geological repository built in the potential host rocks under consideration in Canada. The Canadian research and development program also continually reviews the latest corrosion information developed by other national radioactive waste management programs that consider the use of copper containers in similar deep geological repository concepts. While the current knowledge of the copper corrosion behaviour is relatively mature, areas of uncertainties requiring further study have been identified and priority research areas have been proposed. (authors)