The geologically stable situation of the site ensures the long-term stability of the safety-relevant properties (Explanatory Report on the General Licence Applications, NTB 24-12, Chapter 5).

Future tectonic deformation, temporary climatic changes and erosion are the most important factors considered in connection with long-term geological evolution. The analyses and observations on the long-term geological evolution show that the safety-relevant properties of the multi-barrier system can be maintained for the time period for the assessment of the post-closure phase (Sicherheitsbericht (“Safety Report” (in German)), NTB 24-01, Section 4.5.3).

The geologically stable situation of the site is an important argument for post-closure safety (Post-Closure Safety Report, NTB 24-10, Chapter 10). Based on this, the performance assessment of the barriers shows that the deep geological repository will evolve as expected (Post-Closure Safety Report, NTB 24-10, Chapter 6). As a result, the safety margins for the radiological consequence analyses are several orders of magnitude below the protection criteria, even assuming alternative conceptualisations or hypothetical calculation cases (Post-Closure Safety Report, NTB 24-10, Chapter 8).

The tectonic deformation rates at the site are very low. The site is located in an area of Switzerland with the lowest deformation rates (Geosynthesis of Northern Switzerland, NTB 24-17, Section 6.2).

Larger fault zones were mapped using the results from 3D seismic surveys and can therefore be taken into account when determining the position of the repository. Together with the self-sealing capacity, the long-term stability of the deep geological repository can be ensured with regard to its long-term geological evolution (Geosynthesis of Northern Switzerland, NTB 24-17, Section 4.3.4 and Section 6.2).

The great depth of the repository at the site will ensure that the residual cover will be sufficient to preserve the barrier functions of the Opalinus Clay, even when taking into account all significant erosion processes and evolution scenarios (Geosynthesis of Northern Switzerland, NTB 24-17, Section 6.4 and Section 6.5).

The long-term stability of the geological barrier can also be ensured when taking into account its long-term hydrogeological and hydrochemical evolution (Geosynthesis of Northern Switzerland, NTB 24-17, Section 6.5).

A comprehensive assessment of future climate evolution confirms that, due to the depth and robustness of the Opalinus Clay, its relevant properties will remain stable (Geosynthesis of Northern Switzerland, NTB 24-17, Section 6.3 and Section 6.5).