Glossar

 

Siting regions

On 21st November 2018, the Federal Council decided that, in Stage 3, Nagra should conduct further investigations of the siting regions Jura Ost, Nördlich Lägern and Zürich NordostAll three siting regions are suitable for a repository for high-level waste (HLW), low- and intermediate-level waste (L/ILW) and for a combined repository for both waste types.

Stages 1 and 2 of the site selection process are now complete. On 21st November 2018, the Federal Council gave the starting signal for Stage 3 (see DETEC media release, in German). Nagra is now conducting in-depth investigations of the remaining three siting regions Jura Ost, Nördlich Lägern and Zürich Nordost and will then conduct a safety-based comparison. The investigation programme includes previously conducted seismic investigations as well as Quaternary investigations and deep boreholes.

Results of Stage 2 of the site selection process

The Jura Ost siting region for a L/ILW repository has a large spatial availability in the preferred depth range and offers many possibilities for optimising the underground area in which a repository for L/ILW can be constructed. The containment-providing rock zone (Opalinus Clay together with its confining units) has very suitable barrier properties and the geological situation is favourable with respect to long-term stability.

Despite limitations in terms of the depth of the host rock when considering future erosion processes, the Jura Ost siting region for a HLW repository has favourable spatial availability in the preferred depth range. The containment-providing rock zone has good barrier properties. Because of the restricted depth, erosion could reduce the barrier function of the upper confining units and the formation of erosion channels in the distant future cannot be completely ruled out. However, dose calculations assuming the presence of an erosion channel show that the ENSI protection objective can still be met.

Radioactive waste can be disposed of separately in a repository for low- and intermediate-level waste (L/ILW) and one for high-level waste (HLW) or in a combined repository. In the latter case, the HLW and L/ILW repositories are constructed at the same site and have a common surface infrastructure.

Results of Stage 2 of the site selection process

In its safety-based comparison in Stage 2, Nagra reached the conclusion that the Nördlich Lägern siting region for a L/ILW and HLW repository constructed in the preferred depth range would offer insufficient underground space. There is no possibility to construct the repository at a depth that is optimum in terms of engineering. The available space is larger at greater depth, but the engineering challenges would be considerable and would involve significant damage to the geological barriers. Nagra therefore proposed that the Nördlich Lägern region be placed in reserve for Stage 3. In its evaluation of Nagra's proposal, ENSI concluded that placing the region in reserve was not sufficiently justified and that it should be investigated further in Stage 3 together with Jura Ost and Zürich Nordost. The Federal Council followed ENSI's recommendation and decided on 21st November 2018 that Nördlich Lägern would be carried forward to Stage 3.

Radioactive waste can be disposed of separately in a repository for low- and intermediate-level waste (L/ILW) and one for high-level waste (HLW) or in a combined repository. In the latter case, the HLW and L/ILW repositories are constructed at the same site and have a common surface infrastructure.

Results of Stage 2 of the site selection process

The Zürich Nordost siting region for a L/ILW and a HLW repository has considerable spatial availability in the preferred depth range and offers a wide range of possibilities for optimum delimitation of an underground area in which both the HLW and L/ILW repositories could be realised. The containment-providing rock zone (Opalinus Clay together with its confining units) has very good barrier properties and the geological situation is favourable with respect to long-term stability.

Radioactive waste can be disposed of separately in a repository for low- and intermediate-level waste (L/ILW) and one for high-level waste (HLW) or in a combined repository. In the latter case, the HLW and L/ILW repositories are constructed at the same site and have a common surface infrastructure.

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