Where is the best site for a deep geological repository?
The Federal Government leads the site selection process for a repository. Safety has the highest priority throughout. Nagra is developing the basis for this decision and will announce in 2022 which site it considers most suitable.
Site selection process as specified by the Swiss Federal Government
The site selection process for a deep geological repository is being conducted in accordance with the “Sectoral Plan for Deep Geological Repositories” specified by the Federal Government. For the safer containment of the waste, rock formations such as the Opalinus Clay are crucial. The Opalinus Clay lies at a depth of several hundreds of metres and will serve as host rock for the waste.
In accordance with the specifications laid out in the site selection process, we have investigated the composition of Switzerland’s underground in great detail over many years. We have identified three potential siting regions (see map above) that are mainly located in Cantons Aargau and Zürich as well as in a small section of Canton Thurgau. The regions are called Jura Ost, Nördlich Lägern and Zürich Nordost.
How do we investigate these three regions?
To identify the most suitable of these sites, we investigate each region in great detail. We are drilling deep boreholes to complete the overall picture of the underground geological environment in the three siting regions and will be able to make a conclusive comparison based on the results. Investigations focus on the Opalinus Clay and on the rock formations lying directly above and below it. We determine properties such as thickness, depth, composition and permeability. We have also obtained further information of the underground by conducting additional measurements and drilling boreholes in the three regions.
Where are we with regard to the time schedule?
Around 2022, we will announce which site we consider to be the most suitable. For the Federal Council to be able to make the siting decision, we have to submit a general licence application and numerous documents. These will be reviewed by the federal authorities. A legally valid siting decision can be expected around 2031. Before a deep geological repository can be completed, the Federal Government will have to grant additional licences. Our time schedule contains detailed information on the steps ahead.
What is currently being done in the potential siting regions?
Within the framework of regional participation, affected parties from the three potential siting regions actively discuss aspects related to a deep geological repository. We work together with the siting regions and cantons to determine the sites for the surface facilities of a repository. This is specified in the Sectoral Plan. In the original disposal concept, the encapsulation plant for spent fuel assemblies is part of the surface facility of a deep geological repository. In 2020, one of the issues considered in collaboration with the regions was whether the encapsulation plant could also be constructed at an alternative site such as the interim storage facility.
- Site selection process of the Federal Government for a deep geological repository
- Jura Ost siting region near Brugg
- Nördlich Lägern siting region near Bülach
- Zürich Nordost siting region in the Zürcher Weinland
- Deep boreholes provide an insight into the subsurface
- Previously conducted underground investigations
Cover photo: Boris Baldinger