Launch of Research Program for the Study of Leaking Repository Groundwater Interactions with Cladding and Used Fuel Container Materials During Spent SMR Fuel Storage

Abstract

Upon the completion of a refueling cycle of an SMR (ranging between 7-20 years, depending on design), long-term storage of the used fuel is necessary to ensure the safe decay of various long-lived fission products. The planned long-term solution for spent fuel in Canada is a secure Deep Geological Repository (DGR). With a variety of proposed SMR fuel types, sizes, and compositions, these novel waste forms may require further processing to meet future DGR acceptance criteria, particularly metallic fuels and fuel pins containing a sodium bond. Experiments on groundwater ingress through used storage containers and fuel cladding have not yet been adapted to advanced reactor fuel types.

This paper outlines the planning stages of a collaborative project with NRCan's CanmetMATERIALS laboratory to create a custom leak test cell that will simulate groundwater ingress into a used fuel storage container. Ongoing work with CanmetMATERIALS toward optimized HT9 steel production is highlighted here. This alloy is proposed for use as fuel cladding by various SMR vendors and will be used for testing in this work. Material characterization, with comparison to historic HT9, is shown, validating the use of the new HT9 fabrication method to generate materials towards the current leak testing work. This project will support the pathway to commercialization of SMRs in Canada, ensuring several knowledge gaps are addressed in the safe, long-term storage of spent SMR fuel in a DGR.