Performance of bentonite barriers in a deep geological repository for used nuclear fuel

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Since its inception, nuclear power has been a polarizing topic that brings forth strong opinions and emotions. Even if all nuclear power plants in Canada were shut down immediately, more than two million bundles of used nuclear fuel would remain. Aside from one's opinions regarding the future of nuclear power, its legacy has left a substantial quantity of used fuel that stays active for hundreds of thousands of years. Currently, used fuel is stored at the ground surface. This cannot be a long-term solution, however, due to the close vicinity to potential natural disasters and possible terrorism threats. The collective producers of nuclear waste in Canada, and all other countries exploring options, have determined the long-term solution to be a deep geological repository. The over two million bundles of used nuclear fuel will be placed in containers and surrounded by bentonite-based barriers approximately 500 m below ground surface. In the repository, bentonite barriers will support the waste containers, transfer thermal energy away from the initially hot containers, limit groundwater infiltration, and adsorb radioactive by-products. Nuclear Waste Management Organization (NWMO) is a public agency created by the Canadian Government to coordinate all of the nation's producers of used fuel to work towards a common solution to nuclear waste management. NWMO is currently addressing numerous practical design, manufacturing, and construction issues. There are, however, a number of underlying fundamental engineering science questions arising from the repository context that still require solutions: First, will the bentonite self-heal to function as a competent barrier following saturation with saline groundwater? Second, will internal gas pressures develop to fracture the bentonite barriers leaving a direct link between the waste containers and the environment? This proposal would provide funding for six Doctoral students to research these critical aspects of the repository to ensure the safety of Canadians and the environment.