(Video in German only)
Storage in rock layers deep below the earth's surface is recognised worldwide as the safest solution for managing radioactive waste. Swiss law also prescribes deep geological repositories.
In 1999, the Federal Department of the Environment, Transport, Energy and Communications (DETEC) set up the Expert Group on Disposal Concepts for Radioactive Waste (EKRA). EKRA was given the task of drawing up a basis for comparing the management concepts for Switzerland's radioactive waste that were under discussion. EKRA concluded in its report of January 2000 that only storage in deep geological repositories can guarantee the necessary long-term protection of humans and the environment. It therefore developed the concept of ‘controlled long-term storage in geological repositories’. This combines final storage with the possibility of retrieval and thus with reversibility. Before the storage facility is closed, the concept provides for a longer monitoring period and the operation of a pilot storage facility in line with the principle of monitorability. The EKRA concept was enshrined in the Nuclear Energy Act.
A deep geological repository is an underground facility in which radioactive waste can be permanently stored and safely contained. It ensures the long-term protection of people and the environment from the radiological hazards posed by radioactive waste without the need for long-term human intervention (passive safety). Technical and natural barriers prevent radioactivity from escaping from a deep geological repository. During storage, the waste is sealed tightly in storage containers and these are completely surrounded by backfill. These two components together serve as an engineered barrier. The surrounding dense rock layer of the host rock forms the natural barrier.
In addition to the disposal fields for waste storage, a deep geological repository also includes other underground facility components, such as the pilot repository, the test areas and infrastructure structures that enable safe operation until the repository is closed. Infrastructure is also needed on the surface, for example for waste logistics, and waste management, passenger transport and emergency interventions, operational maintenance, administration and traffic development. Access structures (ramps or shafts) connect the surface facilities with the underground storage areas.
As the requirements for deep storage in deep geological repositories and safety (e.g. with regard to barrier properties or the detection period) are different for HLW and L/ILW, the Swiss storage concept, in line with international practice, provides for separate repositories for HLW and L/ILW (the small amount of ATW is allocated to one of the two repository types). If space and safety permit, a deep geological repository can also be built at a single site comprising two separate repository components for L/ILW and HLW (combined repository). Nagra has submitted a general licence application for a combined repository at the northern Lägern site.
Concept for the construction of a deep geological repository
Test areas
The test areas are an independent part of a deep geological repository. The safety-relevant properties of the host rock or the engineered barriers are analysed in depth. Techniques for storing or recovering the waste and for backfilling and sealing the structures are also being tested. The test areas make it possible to carry out the investigations and verifications planned there under the same conditions as will prevail in the nearby storage area.
Pilot repository
The pilot repository is an independent part of the deep geological repository, separate from the main repository. A significant quantity of radioactive waste is stored there under the same conditions as in the main repository. The pilot repository will be equipped with monitoring systems so that the behaviour of the waste, the backfill and the host rock can be recorded and tracked until the end of the monitoring period. However, there is no monitoring in the main repository. If the monitoring of the pilot repository reveals relevant safety issues on the development of the waste or the safety barriers, appropriate measures can be initiated for the entire repository.
Host rock
Throughout Europe, crystalline, clay and salt rock are being considered for the management of radioactive waste in deep geological repositories. Every type of rock and every host rock has its advantages and disadvantages. The host rock, together with the installed engineered barriers and a long-term geologically stable site, must guarantee the specific safety for the waste in question. The repository concept and design are specifically adapted to the properties of the host rock.
Extensive investigations as part of stage 1 of the Sectoral Plan for Deep Geological Repositories have shown that the clay-rich sedimentary rocks in Switzerland (Opalinus Clay, ‘Brauner Dogger’ and Effingen strata in the Jura Mountains and the marl formations of the Helveticum in the Alps) best fulfil the strict requirements. Crystalline rocks are brittle and therefore, in Switzerland, which is characterised by the folding of the Alps, they are too heavily criss-crossed by fractures and fissures, so that water circulates even at great depths. The evaporite deposits in Switzerland are too thin and are mined as a raw material when they are close to the surface. Salt domes such as those in northern Germany do not exist in Switzerland.
Monitoring period and closure
After the waste has been stored until the final closure of a deep geological repository, a longer monitoring period is planned. During this period, the deep geological repository will continue to be monitored and, if necessary, the radioactive waste can be recovered without great effort. The underground repository areas will be securely closed at this time. However, at least access to the repository level and the control tunnels of the pilot repository will remain possible for the duration of the monitoring period. DETEC determines the duration of the monitoring period following the completion of storage. The current planning assumption is a monitoring period of around 50 years, but the actual duration will then be determined according to necessity and demand.
In the long term, the repository must be passively safe, i.e. without human involvement. Upon expiry of the monitoring period, the Federal Council shall order the closure of the repository, provided the permanent protection of humans and the environment is ensured. All open underground parts of the facility will then be backfilled and the deep geological repository will be left unmonitored. The Federal Council may order further monitoring after closure or carry out environmental monitoring.
Documents
Fact sheets
- Deep Geological Repository. Fact Sheet
(PDF, 204 KB, 22.11.2017) ID: 8885 | 340
- Host Rock. Fact Sheet
(PDF, 498 KB, 22.11.2017) ID: 8889 | 365
Disposal concept
- Beitrag zur Entsorgungsstrategie für die radioaktiven Abfälle in der Schweiz
(PDF, 574 KB, 01.10.2002) ID: 537 | 336
- Disposal Concepts for Radioactive Waste, final report
(PDF, 396 KB, 31.01.2000) ID: 322 | 336
Symposium
- How to keep the memory of nuclear waste alive
(PDF, 3 MB, 08.11.2019) ID: 9890 | 584
- Symposium – Markieren, hinweisen oder vergessen?
(PDF, 7.8 MB, 04.09.2019) ID: 9817 | 584
FAQ
TEST-VERSION - FAQ Abraxas
Wird das Lager verschlossen oder müssen die Abfälle rückholbar sein?
Wird es ein End- oder ein Zwischenlager? Ist die Rückholbarkeit gewährleistet?
Das oder die Tiefenlager? Braucht es ein Lager oder zwei?
Wie wissen wir, ob die Entscheidung für ein geologisches Tiefenlager standhält?
Welche Rolle spielt die Geologie beim Standortentscheid?
Welche Rolle spielt die Geologie bezüglich Sicherheit?
Wird die Geologie durch unabhängige internationale Gutachten geprüft?
Wie und wo wird der Aushub für den Bau von Lager, Tunnels und Schächten gelagert?
Kann der Flächenverbrauch optimiert werden?
Ist eine Bewertung der Sicherheit über eine Million Jahre möglich? Besteht ein Restrisiko?
Welche Garantie gibt es, dass die Sicherheit oberste Priorität hat?
Wie werden das Grundwasser und das Tiefengrundwasser (thermische Quellen) geschützt?
Links
Last modification 07.11.2024