Chemistry Control During Long-Term Storage of SMR Used Fuel

小型模块化反应堆(SMR)被认为在满足社会对无碳、安全和成本效益高的能源需求方面具有巨大潜力。加拿大目前用过的核燃料的拟议长期处置储存在一个深层地质储存库(DGR)中，目前计划将新核技术产生的废物形式也储存在同样的地方。由于DGR存储预计将持续几个世纪，需要考虑水渗透到存储容器中，通过外部防御屏障渗入的情况。由于拟议的SMR燃料类型、大小和成分多种多样，一些燃料废物表格可能需要进一步处理，以满足加拿大未来DGR的废物接受标准。这对于建议使用金属钠作为燃料和燃料包壳之间的一层以改善热传递的SMR来说尤其重要，因为钠与水具有高度的反应性。水通过储存罐和燃料包壳进入的实验尚未适用于SMR乏燃料。与位于安大略省汉密尔顿的CanmetMATERIALS实验室合作，将设计一个定制测试单元，代表当前DGR存储深度防御方法，并委托其进行泄漏测试。实验将模拟地下水进入用过的燃料储存容器，以及一些初始的覆层损坏。将监测由此产生的水-钠键相互作用对当地环境(pH、温度、氢气释放)的变化，包括随后覆层和储存容器材料的降解率。该计划支持SMR在加拿大实现商业化，确保解决在DGR环境中安全、长期存储SMR燃料方面的几个知识差距。

Small modular reactors (SMRs) have been identified as having great potential to meet society's needs for carbon-free, safe, and cost-effective energy. The proposed, long-term disposal of Canada's current used nuclear fuel is in a deep geological repository (DGR), with waste forms from new nuclear technologies currently planned to be stored likewise. As DGR storage is expected to last centuries, scenarios such as water infiltration into storage containers, seeping through the outer defense barriers, require consideration. With a variety of proposed SMR fuel types, sizes, and compositions, some fuel waste forms may require further processing to meet the waste acceptance criteria for Canada's future DGR. This is particularly important for SMRs proposing to use sodium metal as a layer between the fuel and the fuel cladding to improve heat transfer, as sodium is highly reactive with water. Experiments on water ingress through storage canisters and fuel cladding have not yet been adapted to SMR spent fuels. In partnership with the CanmetMATERIALS laboratory in Hamilton, Ontario, a custom test cell, representative of the current defence in depth approach to DGR storage, will be designed and commissioned to conduct leak testing. Experiments will simulate groundwater ingress into the used fuel storage container along with some initial cladding damage. Changes to the local environment (pH, temperature, hydrogen gas evolution) due to the resulting water-sodium bond interactions will be monitored, including the subsequent degradation rate of the cladding and storage container materials. This program supports the pathway to commercialization of SMRs in Canada, ensuring that several knowledge gaps in the safe, long-term storage of SMR fuel in a DGR environment are addressed.