Chemistry Control During Long-Term Storage of SMR Used Fuel

小型模块化反应堆（smr）已被认为具有巨大的潜力，可以满足社会对无碳、安全和具有成本效益的能源的需求。加拿大目前使用过的核燃料的拟议长期处置是在一个深层地质储存库（DGR）中，目前计划同样储存新核技术产生的废料。由于DGR存储预计将持续几个世纪，因此需要考虑诸如水渗透到存储容器中，渗透到外部防御屏障等情况。由于SMR的燃料类型、尺寸和成分多种多样，一些燃料废料形式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层之间的层以改善传热的smr来说尤其重要，因为钠与水高度反应。通过储罐和燃料包壳进水的实验尚未适用于小堆乏燃料。与安大略省汉密尔顿的CanmetMATERIALS实验室合作，将设计并委托定制测试单元进行泄漏测试，该测试单元代表了目前DGR存储的深度防御方法。实验将模拟地下水进入乏燃料储存罐以及一些初始包壳损伤。将监测由此产生的水-钠键相互作用对当地环境（pH值、温度、氢气析出）的变化，包括随后包层和存储容器材料的降解率。该项目为加拿大SMR的商业化提供支持，确保解决在DGR环境下SMR燃料的安全、长期储存方面的一些知识空白。

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.