Abstract

Canada’s plan for the permanent disposal of used nuclear fuel involves sealing the used fuel bundles in Cu-coated carbon steel containers and placing them in a deep geological repository (DGR), surrounded by a compacted swelling bentonite clay which will buffer the containers and seal the DGR , forming an effective multi-barrier containment system. In the current container design specified by the Nuclear Waste Management Organization (NWMO), the Cu coating (~3 mm–thick) will provide corrosion protection, while the carbon steel inner vessel will provide the necessary mechanical strength. A comprehensive program of experimental studies in materials degradation is being conducted to evaluate the longevity of the container in the DGR environment as it evolves from hot and oxidizing to cool and anoxic over time, including localized corrosion, corrosion at a coating defect, corrosion in trace sulphides under anoxic conditions, and the effects of hydrogen absorption. We are also investigating the degradation of the nuclear fuel itself, which could take place according to processes very similar to the corrosion reactions of metals. This talk will provide an overview of the approaches and findings of the corrosion programs in my laboratory.