Sectoral plans are federal planning instruments used for the realisation of infrastructure projects of national importance, such as an airport, a highvoltage power line, a weapons range or, in this case, a deep geological repository.

The Sectoral Plan for Deep Geological Repositories ( pdf SGT(3.01 MB) ) was approved and initiated by the Federal Council in 2008 and defines the site selection procedure for deep geological repositories in Switzerland. The lead authority in this process is the Swiss Federal Office of Energy.

The highest priority of the site selection process under the Sectoral Plan is post- closure safety: the site selection process therefore aims at identifying the most suitable site for the realisation of a deep geological repository in Switzerland.

To this end, 13 criteria related to safety and engineering feasibility were defined to guide the site selection process. These criteria are to be systematically applied in three stages. The safety of the site for the surface facilities can be ensured by their design. For this reason, the concerns of the regions, cantons and neighbouring Germany should also be taken into account when deciding where to place the surface facilities.

STAGE 1

Starting with a nationwide search, potentially suitable siting regions were identified in Stage 1. In 2008, Nagra proposed six geological siting regions for the L/ILW repository and three for the HLW repository.

In siting regions that are suitable for both HLW and L/ILW repositories, the option to realise both repository types at the same site as a so-called combined repository was also considered. With the Federal Council’s decision in 2011, the geological siting regions proposed by Nagra were included in the Sectoral Plan for Deep Geological Repositories.

STAGE 2

At the end of Stage 2, and following a review by the authorities, the Federal Council reduced the number of suitable siting regions in Northern Switzerland to three (Jura Ost, Nördlich Lägern and Zürich Nordost). The Stage 2 decision also confirmed that the Opalinus Clay is best suited for a deep geological repository due to its rock properties and that, out of the whole country, the region of Northern Switzerland is the most suitable due to its tectonic stability and low seismic activity.

In addition, proposals for the placement of the surface facility were developed in collaboration with the siting regions and cantons, resulting in the identification of potential siting areas. These proposals were discussed and reviewed by the regions and cantons and, at their request, supplemented with additional proposals on a caseby- case basis.

Based on the reviews, Nagra proposed at least one location for the surface facility per siting region. These locations were approved by the Federal Council following a review by the authorities.

STAGE 3

In Stage 3, an additional in-depth geological investigation programme was conducted in the remaining siting regions. After systematically evaluating the 13 criteria related to safety and engineering feasibility and applying the pdf ENSI requirements(1.39 MB) , Nördlich Lägern (NL) emerged as the most suitable siting region for both repository types.

The layout of the surface facility was reassessed and concretised in collaboration with the siting regions and cantons. With the “Haberstal” siting proposal in the community of Stadel, Nagra is following the recommendation of the region and takes into account the opinion of the canton.

Several pdf options were compared (3.21 MB)  for the placement of the encapsulation plants. The two remaining options were either a location near the deep geological repository or at the site of the Zwilag interim storage facility.

The decision in favour of the Zwilag site was pdf justified(9.59 MB)  in particular due to the advantages offered by the nuclear facilities that already exist there. These allow synergies to be used in connection with safety-related operational processes. In addition, less land will be required, which will reduce the impact on the landscape and environment.

The sites will be decided with the general licences. In line with the Nuclear Energy Act, the general licences correspond to the first step in the licensing procedure and will mark the conclusion of the Sectoral Plan for Deep Geological Repositories.