What is the surface infrastructure?

The surface infrastructure of a deep geological repository refers to those components that are visible at the surface. These are needed for the construction and operation of the repository.

A deep geological repository requires surface structures. This includes the auxiliary access facility shown in the photograph.

In the future, Switzerland will safely dispose of its radioactive waste in a deep geological repository over a very long time period. The surface infrastructure of a repository is composed of a surface facility and auxiliary access facilities as well as site development infrastructure and landfills for the materials arising from the excavation process. These will be needed for the construction, operation and closure of the repository. The waste itself will be emplaced in deep underground caverns and drifts.

Surface facility: gateway to the deep geological repository

All solidified waste is delivered to the surface facility from the interim storage facility. Low- and intermediate-level waste is packaged in drums that are already suitable for disposal. Before these are emplaced underground, they are enclosed in concrete containers, and any remaining voids are filled with cement. Vitrified high-level waste and spent fuel assemblies are transferred from transport and storage casks to disposal canisters which are then welded shut and examined. These work steps take place in the encapsulation plant for spent fuel assemblies. The waste is then transported to the underground facilities through the main access.

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Our explanatory film shows you how an encapsulation plant works (German with English subtitles).

What belongs to a surface facility?

Diagram of the surface facility of a combined repository for low- and intermediate-level waste as well as for high-level waste.

Elements of the surface facility

  1. Treatment facility for transport casks
  2. Fire station
  3. Garages
  4. Processing plant for backfill and sealing materials
  5. Treatment facilities for waste water and operational waste
  6. Gate
  7. Encapsulation plant for low- and intermediate-level waste
  8. Encapsulation plant for spent fuel assemblies and high-level waste
  9. Administration
  10. Visitor centre
  11. Workshops
  12. Shaft hall
  13. Shaft tower
  14. Ventilation facility
  15. Power supply facilities

Other buildings are also needed to ensure the smooth operation of a repository: workshops, a fire station, security installations, a ventilation facility, an administration area, and a visitor centre. It also includes a processing plant for the backfill material that is used to seal and close the repository drifts and caverns. The entire surface facility of a combined repository requires an area of around six to eight hectares, and the tallest buildings will have a height of around 25 to 30 metres.

“Hot cell” for transferring high-level waste at the interim storage facility in Würenlingen – a similar facility would form the core of an encapsulation plant as part of the surface facility. Photo: Zwilag AG

Encapsulation plant at the Zwilag interim storage facility in Würenlingen?

The encapsulation plant for spent fuel assemblies and high-level waste does not necessarily have to be located at the entrance to the repository; it could also be constructed at the site of the Zwilag interim storage facility.

Auxiliary access facilities: connection to the underground

Aside from the surface facility, that also serves as the main access, auxiliary accesses are required. Auxiliary access facilities include all surface facilities that are needed for the operation and ventilation of the deep geological repository. They represent the surface interface to the repository for the supply or disposal of e.g. ventilation, power and water as well as for the transport of staff and materials. At three hectares, the auxiliary access facility, with its operations and ventilation shaft heads, is the largest structure. The operations shaft head is around 30 metres tall and the ventilation shaft head around 10 metres tall. The auxiliary access facilities for operations and ventilation can also be located in two separate auxiliary access facilities.

Aside from the surface facility and the auxiliary access facilities, additional temporary areas are needed for construction of site installations and landfills for the rock materials from excavation.

Nebenzugangsanlage als Teil der Oberflächeninfrastruktur eines geologischen Tiefenlagers
Configuration of an auxiliary access facility for operations and ventilation

Where to locate the surface infrastructure?

Underground rock formations determine where the emplacement rooms will be constructed. It makes sense to keep the surface infrastructure close to the deep geological repository. The search for a site for the surface infrastructure is carried out in close collaboration with the regions and cantons.

More information is available in the following documents (in German):

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