Materials chemistry ensuring safe, indefinite isolation of used nuclear fuel

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Canada's plan for long-term management of used nuclear fuel relies on natural and engineered barriers to ensure safe containment and isolation of radioactivity from people and the environment. The engineered barrier system, which will employ durable used fuel containers (UFCs) surrounded by bentonite clay buffer boxes will be emplaced in a deep geological repository (DGR) within the vicinity of a willing and informed host community. The copper-coated UFCs hold used nuclear fuel bundles; therefore, their longevity is an important factor in the safe performance of the engineered barrier system. As the repository environment evolves over time, corrosion is one of the degradation modes that could impact the performance of the UFCs, so a key challenge is to confidently predict the corrosion behaviour of the UFCs, and the used nuclear fuel itself, over a period of at least a million years. This Alliance project will provide a detailed understanding of the degradation processes of UFCs and nuclear fuel, using experimental and modeling tools, along with natural evidence from Mother Earth, to build confidence in long-term predictions. The key objective of this project is to investigate the corrosion of copper and used nuclear fuel under anticipated DGR conditions, to improve the underlying scientific understanding and answer the remaining questions raised by scientists, the public, and the nuclear regulators. This 5-year project, funded by NSERC and the Nuclear Waste Management Organization (NWMO) will be performed in partnership with three other companies responsible for nuclear fuel waste management in their home countries: SKB (Sweden), Nagra (Switzerland), and NUMO (Japan). Ultimately information generated through this Alliance project will be integrated into each company's plans for developing UFCs for a deep geologic repository and ensuring its safety and longevity.