Thermo-hydraulic Modelling of the Temperature Distribution in the Siting Regions JO, NL and ZNO
Nagra (2024): Thermo-hydraulic modelling of the temperature distribution in the siting regions JO, NL and ZNO. Nagra Arbeitsbericht NAB 24-24.
In Stage 3 of the Sectoral Plan for Deep Geological Repositories in Switzerland (SGT) (BFE 2008), the three candidate siting regions Jura Ost (JO), Nördlich Lägern (NL) and Zürich Nordost (ZNO) were examined in detail. The broadened site-specific database formed the basis to select the siting region NL for a repository for disposal of SF/HLW and L/ILW for which the general license application will be prepared (Nagra 2025b). The arguments for site selection were reported in Nagra (2025a), encompassing the results of the qualitative assessment of the 13 SGT criteria and quantitative assessment of the site specific repository projects (Nagra 2024h). The thermal and hydraulic conditions in the three siting regions formed an essential part of the geoscientific data base, which fed into the site selection process.
A traceable workflow was followed for the assessment of the thermal-hydraulic conditions in the candidate siting regions, comprising the compilation of available geothermal information at the regional scale, modelling of the thermo-hydraulic conditions at the repository sites and the derivation of the inputs required for the safety analyses. This report documents the pursued assess-ment workflow and provides:
- an overview of the existing geoscientific data base at regional and local scale (geological, hydrogeological and geothermal setting of the siting regions; data base of geothermal properties)
- a description of the model portfolio implemented for the thermo-hydraulic simulations
- an estimation of ambient host-rock temperatures under consideration of the site-specific combined hydrogeological and geothermal conditions
- an evaluation of heat flow associated with the repository structures and the relevant impact on hydraulic conditions and groundwater gradients