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Decommissioning of nuclear facilities

Aerial photo nuclear power plant Greifswald Aerial photo nuclear power plant GreifswaldAerial photo of the Greifswald nuclear power plant (KGR) which has been decommissioned since 1995. Source: EWN GmbH

The final shutdown of a nuclear facility is followed by the post-operational phase, during which work is carried out to prepare for decommissioning. The decommissioning of a nuclear facility following the post-operational phase requires a comprehensive licensing procedure that includes topics such as radiation protection and possible impacts on the environment.

Apart from power reactors, other types of nuclear facilities with a licence under Section 7 of the Atomic Energy Act, such as prototype and research reactors and nuclear fuel supply and disposal facilities, must also be decommissioned at the end of their operating life. BASE holds tables, where German nuclear reactors and facilities in operation and in decommissioning are listed.

The German Atomic Energy Act (AtG) specified individual electricity quantities for the nuclear power plants in operation in Germany that each plant was still permitted to produce before its operating licence finally expired.

Since August 2011, the Atomic Energy Act has also set fixed shutdown dates for all nuclear power plants. This resulted in the gradual shutdown and decommissioning of all power reactors in Germany.

The remaining three nuclear power plants have been taken out of service for good at the end of 15 April 2023.

Contamination and activation

A man dressed in a protective suit removes the surface of the wall Building decontamination through surface removalWork on building decontamination through surface removal Source: EWN GmbH

Any facility where radioactive substances were handled is contaminated with these substances to a greater or lesser extent, meaning that residues of these substances can be found

  • on surfaces,
  • in tanks,
  • in tubing, etc.

Such contamination can be removed via appropriate decontamination procedures. For this purpose, the affected surfaces will be removed mechanically or chemically. If this is successful, the respective substances can be recycled or disposed of as non-radioactive material. Only the removed surface material (and, if applicable, auxiliary materials) will remain as radioactive waste.

Decontamination thus offers an opportunity to reduce the total volume of radioactive waste during the decommissioning phase of a nuclear facility.

An activation of the materials near the core also occurs in reactors, i.e. a very small part of the material itself is affected by the neutrons during reactor operation and thus becomes radioactive, too. This activation affects the entire volume of material and thus cannot be removed by decontamination techniques. These materials are disposed of as radioactive waste or stored for a certain period of time with the aim of reducing activity (cf. decay storage).

Information on decontamination

What is decontamination? Is acid used in the process?show / hide

With light-water reactors, the components (e.g. pipes, pumps) in the primary circuit that come into contact with cooling water will experience a build-up of activity during operation. The dose rate values in the vicinity of the primary circuit will increase as a result. This implies a potential radiation exposure for the personnel working in this area of the plant, which is why the so-called (primary circuit) decontamination has been carried out in reactors worldwide for more than 50 years to reduce this activity.

During this decontamination, parts of the primary circuit are cleaned by means of qualified procedures and special chemicals, such as acid. This can reduce the existing activity by more than 90 per cent. The intensity of decontamination and the associated removal of material can be controlled and depends, among other things, on whether the nuclear power plant will continue its operation or be dismantled afterwards.

Why is decontamination necessary prior to dismantling?show / hide

For one thing, decontamination reduces the radiation exposure for the personnel. Secondly, decontamination reduces the amount of radioactive waste that must be placed in interim and final storage.

Whether the decontamination of the primary circuit is planned in preparation for dismantling remains at the operator's discretion. The implementation must be covered by a valid licence, and is supervised by the competent authority. Decontamination can thus be commissioned by the NPP operator during the post-operational phase of the NPP - within the framework of the operating licence. However, decontamination can also take place during the decommissioning phase of a nuclear power plant - after a corresponding licence has been granted.

Is decontamination also carried out at nuclear power plants abroad?show / hide

(Primary circuit) decontamination is an established procedure that represents the state of the art and has been carried out worldwide for over 50 years. In some NPPs, power operation was subsequently resumed, for example at the Oskarshamn 1 NPP in Sweden or the Loviisa2 NPP in Finland. Decontamination in preparation for decommissioning was carried out, for example, at the US nuclear power plant Haddam Neck and at many German nuclear power plants (e.g. Stade, Obrigheim, Biblis).

Decommissioning strategies

A man dressed in a protective suit operates a machine for thermal disassembly of a component Thermal disassembly of a componentThermal disassembly of a component in the central active workshop Source: EWN GmbH

There are various decommissioning strategies: for example, plants can be

  • either dismantled immediately after the shutdown, or
  • initially be safely enclosed for a few years, to achieve a reduction in the activity inventory due to radioactive decay before subsequent dismantling (safe containment)..

The Atomic Energy Act requires power reactors whose licence for power operation has expired to be decommissioned and dismantled immediately.

Decommissioning strategies can also be a combination of these two basic alternatives. The decommissioning process as a whole can be optimised, for example, by removing large components and storing them temporarily until they are dismantled at a later stage.

A large number of power and prototype reactors, research reactors and nuclear fuel supply and disposal facilities have already been decommissioned in Germany. Some plants have already been completely dismantled, i.e. the plant buildings have been demolished and the plant site has been cleared and re-cultivated. Practical decommissioning experience is therefore available in Germany.

Guide for the decommissioning of nuclear facilities

There is no separate set of regulations for decommissioning nuclear facilities in Germany. Rather, decommissioning was integrated into nuclear legislation. The Decommissioning Guide was developed to provide an overview of the legal aspects to be considered during decommissioning.

The guideline for decommissioning, safe enclosure and dismantling of plants or parts of plants according to Section 7 of the Atomic Energy Act is available for download from the Handbook on Reactor Safety and Radiation Protection under the heading "3 Announcements of the BMUV and the BMI formerly in charge".

State of 2023.11.01

© Federal Office for the Safety of Nuclear Waste Management