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Decommissioning a nuclear power station

Demolition of the cooling towers at Chapelcross Power Station

Nine of the UK's nuclear power stations have ceased operation and are at various stages of decommissioning. Even after a nuclear power station reaches the end of its lifespan, it must be carefully managed while there are still radioactive hazards associated with the site. Depending on the strategy used, this decommissioning process can take decades.

Methods of decommissioning

The International Atomic Energy Agency (IAEA) has defined three options for decommissioning nuclear power stations. These have been adopted as an international standard.

  • Immediate dismantling: the power station is defuelled, dismantled and decontaminated as soon as possible after shutdown. The station's operating staff can contribute their skills and experience to the process, and the site can be made available for reuse relatively quickly.
  • Safe enclosure (also known as Safestore): any high-level radioactive waste that can be removed is made safe elsewhere. The defuelled power station is monitored for 40–80 years while any remaining radioactivity decays to a safe level. This makes decontamination and dismantling simpler and safer.
  • Entombment: all the radioactive material is gathered in one part of the power station, which is then encased in concrete strong enough to contain the radioactivity until it decays to a safe level.

The decommissioning option being used for the UK's existing Magnox reactors and advanced gas-cooled reactors (AGRs) – most of which have either already closed or are nearing the end of their lives – is safe enclosure (Safestore). The option that will be used for the pressurised water reactor (PWR) at Sizewell B, and for the European pressurised water reactors (EPRs) EDF Energy plans to build at Sizewell and Hinkley Point, is immediate dismantling.

Responsibility and regulation

The companies that own and operate the UK's nuclear power stations are also responsible for covering the cost of decommissioning them. They are required to set aside funds for decommissioning throughout the life of each power station – within their own finances, in a Government-run scheme, or in an independent trust.

The Office for Nuclear Regulation (ONR), the Nuclear Decommissioning Authority (NDA) and the Environment Agency (or Scottish Environment Protection Agency) are the bodies responsible for overseeing and regulatiing decommissioning activities in the UK.

Information sources