Grant: Alliance Grants

Nuclear power is considered in Canada to be a clean energy source for combating climate change. However, an often cited drawback is the remnant spent nuclear fuel; at this time ~3.2 million used fuel bundles are in interim storage facilities in Canada, which require safe storage for up to 1 million years. To address this, The Government of Canada initiated Adaptive Phase Management (APM) for safe and responsible storage of spent fuel in a deep geological repository (DGR), and the Nuclear Waste Management Organization (NWMO) was established to lead this initiative. The DGR is a multi-barrier system where fuel bundles are placed in Cu-coated used fuel containers (UFC), embedded in clay, and surrounded by bedrock. The NWMO has established a world-leading research program investigating the performance of DGR materials, specifically understanding materials selection and corrosion behaviour. However, there are still knowledge gaps to address, especially with the advent of small modular reactors (SMRs), which will have different spent fuel forms and/or geometries. For example, tensile stress can develop on UFCs designed for SMR spent fuel or due to uneven buffer swelling. Although this tensile stress is expected to be low, its effect on potential environmentally-assisted cracking (EAC) remains unknown, specifically mechanistic understanding. Developing a nanoscale understanding of EAC is particularly important. This Alliance program will seek to further our fundamental understanding of EAC and corrosion of Cu at the nanoscale. A team of 3 PIs at Queen's University in partnership with the NWMO aims to leverage novel facilities and multi-disciplinary expertise to perform mechanistic studies using novel electron microscopy techniques, experimental methods, and advanced modelling to evaluate the corrosion, EAC, and metallurgy of the proposed UFC Cu coating. The team will train highly qualified personnel (HQP) with relevant skills and knowledge applicable to materials performance in the DGR, including CANDU and SMR designs. The project will provide insight on nanoscale degradation mechanisms for Cu and contribute data to the NWMO Cu corrosion allowance.