Exploratory boreholes
Geological boreholes provide a direct insight into the underground environment and its structure. These exploratory boreholes are also called deep boreholes.
Up-to-date information on the deep boreholes running since early 2019 can be found on the web page “News on the deep boreholes”.
Two drilling techniques are widely used:
Using a roller bit crushes the rock in the borehole. Drilling fluid is pumped through the drill pipe and flushes the fragments of rock (drill cuttings) to the earth's surface. This drilling fluid is circulated in a closed cycle.
Core drilling is a more complex technique: In cored boreholes, core bits crush only the rock at the borehole walls and the rock core inside the drill bit remains intact. The core is loosened and transported to the earth's surface where it can be investigated more closely.
To complement these investigations, various borehole measurements, so-called logs, as well as further hydrogeological and rock-mechanical tests are conducted.
Between 1982 and 1999, Nagra drilled eight boreholes in Northern Switzerland with depths between 1000 to 2500 metres. These were part of the investigation programme for the demonstration of disposal feasibility (Entsorgungsnachweis). The boreholes are:
| Böttstein | 1501 metres (1982 to 1983) |
| Weiach | 2482 metres (1983) |
| Riniken | 1801 metres (1983 to 1984) |
| Schafisheim | 2006 metres (1983 bis 1984) |
| Kaisten | 1306 metres (1984) |
| Leuggern | 1689 metres (1984 to 1985) |
| Siblingen | 1522 metres (1988 to 1989) |
| Benken | 1007 metres (1998 to 1999) |
Exploration applications
According to the Nuclear Energy Act, deep boreholes drilled by Nagra require a permit from DETEC (Federal Department of the Environment, Transport, Energy and Communications). Once the permit for a deep borehole has been granted, the drill site can be built. The first borehole went into operation in early 2019.
With a view to Stage 3 of the Sectoral Plan process, Nagra submitted eight applications for each of the siting regions Jura Ost and Zürich Nordost in September 2016. The applications for the Nördlich Lägern region followed in August 2017.
The applications were open for public inspection in the affected communities in the Jura Ost and Zürich Nordost regions in spring 2017. Public inspection in Nördlich Lägern began on 1st November 2017. All public inspections were completed in January 2018. To date, DETEC has granted 16 of the total of 23 applications. These are: Bözberg 1, Bözberg 2, Bülach, Effingen 1, Eglisau, Marthalen, Remigen 1, Rheinau, Riniken 2, Stadel 1, Stadel 2, Stadel 3, Trüllikon 1, Trüllikon 2, Trüllikon 3 and Zeihen. Other permits are expected in the coming months.
The planned exploratory boreholes are:
- Jura Ost region: Zeihen, Effingen 1, Riniken 2, Remigen 1, Remigen 2, Bözberg 1, Bözberg 2 and Effingen 2
- Nördlich Lägern region: Weiach, Bülach, Stadel 1, Eglisau, Stadel 2, Glattfelden and Stadel 3
- Zürich Nordost region: Uhwiesen, Laufen, Trüllikon 1, Trüllikon 2, Rheinau, Dachsen, Marthalen and Trüllikon 3
The applications for the individual boreholes can be downloaded here (in German).
