During Stage 3 of the site selection process, Nagra was able to obtain many new data and findings. Based on these, it revised its assessment of the Nördlich Lägern siting region.
In Stage 2 of the Sectoral Plan, Nagra had argued that Nördlich Lägern looked less suitable from an engineering perspective than the other two siting regions. At the time, the Swiss Federal Nuclear Safety Inspectorate (ENSI) criticised the fact that the assessment regarding the structural concerns was not sufficiently substantiated with data. Accordingly, ENSI stipulated that in Stage 3, the region had to be further investigated in great detail, just like Jura Ost and Zürich Nordost.
So why Nördlich Lägern after all?
In the end, the investigations in Stage 3 delivered better results than expected. From today’s perspective, we can say: Nagra’s assessment in Stage 2 was too cautious. It is possible to construct a safe deep geological repository in all three siting regions.
With the help of the comprehensive data basis that is available now, Nagra was able to reassess the suitability of the region in terms of structural engineering. In addition, Nagra decided in the meantime to line the excavated tunnels with prefabricated concrete elements. These so-called “Tübbinge” facilitate tunnel construction at greater depth. Nagra’s revised assessment is therefore based on the improved data basis and the new lining technique.
Advantages of Nördlich Lägern at a glance
Site selection process has proven its worth
The objection of the supervisory authorities proved to be justified. This shows that the process stipulated in the “Sectoral Plan for Deep Geological Repositories” works. Nagra has learned a great deal from this and is convinced that this has strengthened the site selection process and confirms that collaboration between the various stakeholders will lead to the safest solution.