Increasing Confidence in Localized Corrosion Allowance of Copper Coated Steel Containers

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Canada's plan for the long-term management of its used nuclear fuel is to safely contain and isolate the used nuclear fuel in a deep geologic repository (DGR). In line with international best practices, both natural and engineered barriers will be used for safe and long-term containment of used nuclear fuel. A key component of the engineered barrier system is the used fuel container (UFC) that consists of a strong interior steel container coated with a corrosion resistant copper coating. What makes the Canadian design unique is the thin copper coating, a result of Canadian innovation, as prototype fabrication has been performed by Ontario industry with support from Quebec and Canadian research institutes. However, this decrease in thickness merits the extensive evaluation of the coating's corrosion behaviour to ensure their longevity for the safe containment and isolation of radioactive materials from Canadians and environment. The coatings' microstructure and the DGR solution chemistry influence their corrosion behaviour. A thorough investigation on how the coating's microstructure and radiation products influence non-uniform (localized) corrosion mechanisms is of extreme importance to avoid penetration of the UFC and exposure of radioactivity to the surroundings.This Alliance project's key objective is to increase the confidence in the safety and localized corrosion allowance of the UFCs using a multiscale electrochemical approach. The likelihood and long-term prediction of localized corrosion of the UFCs will be explored in aggressive DGR conditions, including gamma radiation exposure, using advanced electrochemical methods to further our understanding of copper corrosion and confidence in the proposed UFC/DGR system. This 3-year project, funded by the Nuclear Waste Management Organization (NWMO) and NSERC, will be integrated into the partner's manufacturing strategies and licensing phase to build a safe and reliable repository.