Sequence of decommissioning

In an ideal situation, the decommissioning order is legally valid on the day after the final shutdown. Then in addition to the activities which are covered by the operating permit, dismantling measures can also already start. Preparatory works for the dismantling however are always done during the post-operation, immediately after the final shutdown.

Equipment for processing, decontamination and disassembly of dismantled materials. The further material treatment is carried out externally, e.g. in the plasma system of ZWILAG.

The dismantling of a nuclear power plant fundamentally contains the following steps, some of which are carried out in parallel:

• Removal of the nuclear fuel. This can take several years. On the one hand, the fuel elements must have decayed to the extent that they can be transported in compliance with strict specifications, and on the other hand a suitable interim storage must be available.
• Cleaning of the complete circuits of the plant, usually described as system decontamination. The radioactivity is removed to a large extent. This means that during future dismantling, substantially fewer radiation protection measures are required.
• Removal of the irradiated components. These include the reactor pressure vessel including its internals as well as other components from the primary circuit, which are removed and later dismantled. Part of this can be disposed of after suitable cleaning as non-radioactive material and reused. The rest is disposed of as radioactive waste.
• Removal of the remaining system parts with all equipment. Everything is removed, radioactive material is cleaned, if possible released as inactive or otherwise disposed of as radioactive waste. Radioactivity in the building structure is also removed.
• Removal of all controlled areas, i.e. all area which require radiological monitoring. This is done by the regulatory body after evidence has been provided that no radioactivity which exceeds the limits is present any more in the remaining buildings and the site, and therefore that the plant no longer constitutes a radiological hazard.
• Removal of the site from the nuclear legislation by the licensing authority.
• Building structures are dismantled conventionally or reused outside of the nuclear energy legislation.