Gas-related Property Distributions in the Proposed Host Rock Formations of the Candidate Siting Region in Northern Switzerland – Updated Database 2024
Nagra (2024): Gas-related Property Distributions in the Proposed Host Rock Formations of the Candidate Siting Region in Northern Switzerland – Updated Database 2024. Nagra Arbeitsbericht NAB 24-27.
In Stage 3 of the Sectoral Plan for Deep Geological Repositories in Switzerland (SGT), the three potential siting regions Jura Ost (JO), Nördlich Lägern (NL) and Zürich Nordost (ZNO) were examined in detail. The broadened site-specific database formed the basis for selecting the Haberstal site in the NL siting region for a repository for the disposal of spent fuel and high-level waste from reprocessing (SF/HLW) and low- and intermediate-level waste (L/ILW). Nagra is currently preparing the general licence application for the Haberstal site in the NL siting region. This report summarises and integrates the lines of evidence which have proven beneficial for broadening the existing gas-related database of the host rock (Opalinus Clay) and the confining geological units in the three siting regions. Gas-related properties and thermo-hydro-mechanical (THM) properties of the geological barriers and the engineered barrier system (EBS), such as porosity, intrinsic permeability, relative permeability, capillary pressure, thermal conductivity, and heat capacity, which all provide input for the qualitative assessment of the 13 SGT criteria in the context of the site selection process and for the modelling of gas release related to the performance assessment (PA) and safety assessment (SA), contributing to the safety case for a repository in the NL siting region.
The report provides a brief introduction to the fundamentals of gas transport in porous media. A comprehensive survey of the available field and laboratory data is compiled and documented. Data sources encompass previous site investigation programmes, the latest deep borehole campaign (TBO) in the three siting regions, RD&D activities at the Mont Terri Underground Rock Laboratory (URL) and on other international research platforms (including the EURATOM projects NF-PRO, FORGE and EURAD-GAS). The gas-related databases are interpreted and subjected to model-supported analyses, finally constituting the gas-related reference dataset for the Opalinus Clay, for the confining geological units in the three siting regions and for the EBS.