Sizewell: nuclear regulation

Environment Agency's regulation of Sizewell A, B and C and how you can find out more about environmental permits and other activities at these nuclear sites.

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The Environment Agency:

The Sizewell nuclear power stations are in Suffolk, England on the North Sea coast.

Sizewell A was Sizewell’s first nuclear power station. It operated from 1966 to 2006 and is being decommissioned.

Sizewell B is a Pressurised Water Reactor, the first to be constructed in the UK. It will stop generating electricity in 2035.

EDF nominated Sizewell as a potential site for a new nuclear power station. EDF’s new nuclear build company, SZC Co, is proposing a twin reactor nuclear power station, Sizewell C, at the site.

Environment Agency’s regulation at Sizewell

The Environment Agency is the independent environmental regulator for the nuclear industry in England. It makes sure that nuclear power stations meet its high standards of environmental protection. It regulates the Sizewell sites working closely with the Office for Nuclear Regulation (ONR).

See also information on radioactivity in the environment and how levels of radioactivity are monitored and assessed at and around the Sizewell sites.

Sizewell A

Sizewell A is being decommissioned. The Environment Agency regulates how Magnox manage and dispose of radioactive waste from decommissioning at the site.

Environment Agency nuclear regulators attend and report to the Sizewell site stakeholder group for Sizewell A.

You can find and request information about the environmental permits for Sizewell A on the public register. You need to search under ‘Magnox’.

You can find out more about the decommissioning of Sizewell A from:

Sizewell B

The Environment Agency regulates how EDF operates the power station at Sizewell B. In particular, it regulates discharges from the site and radioactive waste disposal.

Environment Agency nuclear regulators attend and report to the Sizewell site stakeholder group for Sizewell B.

You can find and request information about the environmental permits for Sizewell B on the public register. You need to search under ‘EDF’.

You can access reports about Sizewell B from ONR.

You can read information about the power station from EDF.

Sizewell C

Power station design proposed for Sizewell C

The Environment Agency and ONR developed an assessment process called Generic Design Assessment (GDA). They use this to scrutinise new nuclear power station designs before they are built.

They used the GDA process to assess the Areva UK EPR reactor design that EDF is proposing for its Sizewell C site. The assessment process ended in December 2012 and the Environment Agency and ONR concluded that the reactor design is ‘acceptable’. This means that people and the environment will be properly protected if this reactor design is constructed and operated in the UK.

You can read reports about the GDA assessment process for this design.

The Environment Agency will use information from its assessments in the GDA process to make decisions on EDF SZC Co’s environmental permit applications for Sizewell C.

Environmental permits for Sizewell C

EDF SZC Co will need to apply for a number of permits from the Environment Agency to build and operate Sizewell C. The company is applying for permits in 2020 to:

  • dispose of and discharge radioactive wastes
  • operate standby power supply systems using diesel generators
  • discharge cooling water and liquid effluents into the North Sea

The Environment Agency will also carry out a Habitats Regulation Assessment (HRA) for these permits. The HRA checks whether the activity could have a significant negative effect on protected species such as migratory fish or birds, or on protected areas nearby.

The Environment Agency must make sure that activities carried out under an environmental permit will not have a negative effect on vulnerable species and habitats or contribute to their loss.

EDF SZC Co will also apply to the Environment Agency for environmental permits that will allow it to carry out site preparation and construction activities.

The Environment Agency will continue to receive applications for environmental permits as the development of Sizewell C progresses.

Environment Agency staff attend and present information to EDF’s Sizewell C Community forum.

You can read information about Sizewell C from EDF.

Planning process for Sizewell C

EDF SZC Co consulted on its pre-application proposals in stages. This is part of the planning process that leads up to the company making an application to the Planning Inspectorate for a DCO for the site.

EDF SZC Co has completed four stages of consultation. Responses informed the development of its plans and its DCO application. Read the Environment Agency’s responses to EDF’s consultation.

You can find out more about the planning process for Sizewell C from the Planning Inspectorate.

Environment Agency’s environmental permitting engagement plan

See how the Environment Agency proposes to engage with the public and stakeholders on the 3 operational permits EDF SZC Co will apply for in 2020.

You can send us feedback on our approach. Email comments to

You will be able to respond to our consultation on the permit applications and the draft permits.

Published 24 January 2020