Interim storage facility (nuclear technology)

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An interim storage facility related to nuclear energy is a temporary storage location for spent fuel and / or radioactive waste . An international overview can be found in the article List of Nuclear Power Plants under Interim Storage .

Purpose of a fuel element interim storage facility

When fuel assemblies are no longer useful for generating energy in nuclear power plants , they are unloaded from the reactor and placed in an interim storage facility. There they are kept for several decades until the decay heat has subsided to the point where the fuel to a repository could be brought if there was a repository for high-level radioactive waste.

Types of fuel element storage facilities

There are two basic types of interim storage facilities for spent fuel elements :

  • Wet storage ( decay basin , decay system ): the spent fuel elements are located here in a water basin. The water serves on the one hand to cool the fuel assemblies and on the other hand to shield the radiation; it must be actively cooled and cleaned - with the corresponding energy consumption.
  • Dry storage : Here the fuel assemblies are stored in transport casks (for example of the Castor type) and cooled by circulating air . There is a global trend towards the increased use of dry storage, as this does not require active cooling systems and can also be set up outdoors (e.g. USA). With dry storage, the safe containment of the radioactive inventory is ensured by the hermetically sealed container in which the fuel elements are placed dry. The hall and its systems take on additional security and protective functions (e.g. monitoring of the containers for leaks, access control, protection against external influences, etc.). Only a few interim storage facilities have a so-called hot cell , which is a room in which a defect in the container seal can be repaired.

On-site interim storage facility for spent fuel elements

Interim storage facility at the Grafenrheinfeld nuclear power plant
Interim storage facility at the Isar nuclear power plant
Interim storage facility at the Gundremmingen nuclear power plant

In Germany, the Atomic Energy Act stipulates that the spent fuel elements unloaded from the reactor must be temporarily stored at the location of the nuclear power plants. Transports to reprocessing plants , which until recently were carried out by many nuclear power plants, have not been permitted since July 1, 2005. As a result, the power plant operators applied for and built so-called on- site interim storage facilities. All new on-site interim storage facilities are dry storage facilities. In order to bridge the time up to the commissioning of these stores, some nuclear power plants had applied for and built interim stores in which the fuel elements were to be stored temporarily (up to around five to six years). The interim storage facilities went out of operation with the commissioning of the interim storage facility, as the containers stored there were relocated to the interim storage facilities.

In each interim storage facility there is a reception area in which arriving containers are unloaded from the transport vehicle and checked. From there the transport to the actual storage area or to the maintenance room takes place. The storage area is again sealed off with heavy steel gates for radiation protection and access control reasons. It is completely or at least in a larger area around the container as a control area. Each interim storage facility has a 130 t crane to move the containers. When transporting containers, the crane is mechanically limited so that the containers cannot be lifted higher than 25 cm above the hall floor.

In the maintenance area, minor repairs and checks can be carried out on the container. For this purpose, it is equipped with a maintenance platform that can be raised on the container. In the case of on-site interim storage facilities, the concept of welding on a joint cover is pursued in the case of primary cover defects, in which the primary cover is not opened but a further cover is welded on. If fuel elements are to be reloaded into another container, they must be transported to another facility (usually the nearby nuclear power plant).

In the on-site interim storage facilities, the containers are usually stored in so-called figure-of-eight groups (2 × 4), which means that eight containers are placed closer together (approx. 1 m). There is then about 3 m space for the next group. If a container in a row of four has to be brought into the maintenance area, the containers in front of it must be moved to separate parking positions in the reception area, as it is not possible to remove the containers through the lane between the associations.

The interim storage facilities close to the site have been approved by the Federal Office for Radiation Protection to operate for 40 years, since it is assumed that a repository will exist until then.

Central interim storage facility for spent fuel elements

Ahaus transport container warehouse

In addition, there are two central dry storage facilities away from nuclear power plant locations. One of them is the Gorleben nuclear waste storage facility . According to the permit, vitrified high-level radioactive waste from reprocessing can also be stored there in addition to the fuel elements. The other is the Ahaus nuclear waste storage facility in West Munsterland . Medium-level waste from reprocessing and other radioactive waste are to be stored here in the future. Due to the newly established interim storage facility, fuel element transports from nuclear power plants to Gorleben and Ahaus are not expected for the time being - however, this is only a postponement until a repository is available. However, the postponement of transport does not apply to the vitrified waste from reprocessing and also not necessarily to fuel elements from German research reactors for which there are no suitable interim storage facilities at the location of the reactors.

In Switzerland - as a dry storage facility - there is a central interim storage facility in Würenlingen for nuclear waste under the name Zwilag . For industrial and medical radiological waste, there is the federal interim storage facility at the same location , also a dry storage facility (source: ENSI annual reports).

Decentralized interim storage facility for radioactive waste

There are interim storage facilities for radioactive waste at every nuclear power plant, at the nuclear research centers and other nuclear facilities . Radioactive waste from small producers from medicine , industry and research are mostly to the set up of the provinces by law State collecting delivered. Here, the low to medium level radioactive waste is temporarily stored in barrels or containers until the Konrad mine is available as a repository . The required conversion was originally supposed to be completed in 2013, but is now expected to be completed in 2019.

Another interim storage facility is the Interim Storage Facility North (ZLN) in Lubmin on the site of the decommissioned power plant. It was originally only intended for fuel elements from the decommissioned nuclear power plants in Rheinsberg and Greifswald . In December 2010, however, waste from the Karlsruhe research reactor and the nuclear ship Otto Hahn were also stored there. These came from the French Cadarache . The Federal Government justified this by stating that it had a take-back obligation towards France and that Lubmin was the only interim storage facility owned by the Federal Republic.

literature

Individual evidence

  1. ↑ a b Julia Beißwenger: 200 meters in the Castor: The Akw Grohnde in Lower Saxony. In: Deutschlandfunk. Research Current. July 26, 2011. ( accessed on July 31, 2011 from dradio.de )
  2. ↑ New problems with nuclear waste. In: Salzgitter newspaper. September 24, 2010, p. 22.