Development of stress analysis software to guide waste package design for use in Deep Borehole Disposal of high-level nuclear waste.

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Deep Borehole Disposal (DBD), a potentially transformative disposal concept largely pioneered at the University of Sheffield, has gained global attention as a potentially safer, more secure and cost-effective solution to the disposal of HLW and spent fuel. In DBD, the waste containers are stacked vertically within the waste deployment zone of the borehole (lowest 1-2 km). It is important when considering the post-operational safety case to ensure that the containers (and any overpacks) are able to withstand both the vertical load stresses and a large hydrostatic pressure without compromising the mechanical integrity of the packages.The PhD student would focus on the stress analysis for the canister design where the aim is to guide the thickness of the canisters or overpack walls such that they withstand the downhole pressure and the load of containers in a vertical columned stack. The finite element method (FEM) will primarily be used. Detailed nonlinear models will be developed to achieve an eventual series of nuclear waste filled canisters while at the same time considering the interaction of the surrounding environment (e.g. soil/rocks). This approach would then be implemented into a tailored software package for this application that would allow engineers to quickly and easily find the minimum thickness and number of canisters for a given disposal scenario (waste type, hole diameter, etc).