Finite Element Analysis of Transient Heat Transfer in and Around a Deep Geological Repository for a Spent Nuclear Fuel Disposal Canister and the Heat Generation of the Spent Nuclear Fuel

This paper presents a finite element analysis of transient heat transfer in and around a hypothetical deep geological repository for a spent nuclear fuel (SNF) disposal canister and the heat generation of the SNF inside the canister to provide basic information for dimensioning the repository and configuring the repository components. Three geometric models are compared to determine the most suitable assuming the periodic allocation of boreholes where canisters are deposited. These models consist of several different material regions. Each model is horizontally limited to a region around and including a single canister, bounded by midsurfaces with variant distances between adjacent deposition tunnels and adjacent canisters, and vertically bounded by the ground surface located 500 m above the deposition tunnel and the surface located 500 m below the bottom of the borehole. Using a commercial finite element analysis code and detailed realistic finite element models of repository components, transient heat transfer analyses are carried out for up to 1000 yr after deposition of the canister into the repository. Time-dependent temperature curves at selected positions are obtained for each geometric model. Various temperature distribution changes of material regions in geometric models are also obtained.