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.

Applies to England

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.

Sizewell C Company (SZC Co.), EDF’s new nuclear build company has been granted development consent to build a twin reactor nuclear power station at the site.

Environment Agency’s regulation at Sizewell

The Environment Agency is the independent environmental regulator for the nuclear industry in England. We make sure that nuclear power stations meet our high standards of environmental protection.

We regulate the Sizewell sites, working closely with the Office for Nuclear Regulation (ONR).

We have published information:

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, we regulate 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’.

The Environment Agency issued a permit variation on 1 September 2021. The decision follows a consultation on an application from EDF Sizewell B company (EDF Energy Nuclear Generation Ltd) to increase the limit for Carbon-14 discharges to air.

You can:

Sizewell C

Power station design for Sizewell C

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

We used the GDA process to assess the Areva UK EPR reactor design that will be built at the 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 our GDA process assessments to help inform decisions on SZC Co’s environmental permit applications for Sizewell C.

Environmental permits for Sizewell C

SZC Co applied for permits from the Environment Agency to build and operate Sizewell C in June 2020. They applied for the permits under the name of NNB Generation Company (SZC) Ltd. These are permits are 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 consulted on:

The Environment Agency published their decision in March 2023.

The Environment Agency has carried 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.

SZC Co must also apply to the Environment Agency for environmental permits that will allow it to carry out:

  • site preparation
  • construction works
  • associated developments such as a park and ride

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 Sizewell C’s community forum.

You can read information from the company about Sizewell C.

Licensing the Sizewell C nuclear site

ONR is responsible for licensing proposed new sites for nuclear power stations. On 30 June 2020 ONR received an application from NNB Generation Company (SZC) Ltd for a nuclear site licence for its site at Sizewell in Suffolk. It issued a progress statement in July 2022.

You can read information about ONR’s regulation of Sizewell C.

Planning process for Sizewell C

SZC Co consulted on its pre-application proposals in stages. This part of the planning process led to the company making an application to the Planning Inspectorate for a Development Consent Order (DCO) for the site.

The consultation documents are published on the Sizewell C consultations website.

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

As a statutory consultee in the planning process the Environment Agency provided advice and information to the Planning Inspectorate throughout the process. Advice note 11 on the Planning Inspectorate website has information about the Environment Agency’s role in the planning process.

Examination of the DCO application concluded on 14 October 2021. The Planning Inspectorate Examining Authority submitted a report to the Secretary of State for Business, Energy and Industrial Strategy on 25 February 2022. The Secretary of State granted development consent for the Sizewell C Project on 20 July 2022.

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

Environment Agency’s environmental permitting engagement plan

Decisions about environmental permits will always be the Environment Agency’s responsibility. However, we want these decisions to be better informed through good engagement. We want to understand people’s views and, where relevant, use them to help inform our permit assessments.

See how the Environment Agency is engaging with the public and stakeholders on the 3 operational permits SZC Co applied for in 2020, and other environmental permits for the Sizewell nuclear sites.

You will be able to respond to our consultations on permit applications and draft decisions.

Contact us

You can contact us at

Published 24 January 2020
Last updated 28 March 2023 + show all updates
  1. Updated with information about the Environment Agency's decision on environmental permits for Sizewell C.

  2. Updated the information to reflect the end of the consultation. Updated the company name for Sizewell C.

  3. Added information about the Environment Agency's consultation on its proposed decisions and draft permits that NNB Generation Company (SZC) Ltd applied for in June 2020.

  4. In 'Environmental permits for Sizewell C', added that we will consult on our draft decisions in summer 2022. In 'Planning process for Sizewell C', added a link to EDF SZC Co’s consultation documents and added information about the status of the Development Consent Order application.

  5. We have updated information about a permit variation decision for Sizewell B.

  6. Updated information on how we engage, including our consultations on a permit variation for Sizewell B and permit draft decisions for Sizewell C.

  7. The Environment Agency is consulting from 19 August to 1 October 2020 on a permit variation application from EDF’s Sizewell B company (EDF Energy Nuclear Generation Ltd). We have included a link to the consultation.

  8. Updated following the launch of our July-October consultation on EDF's NNB Generation Company (SZC) LTD's application for 3 environmental permits to operate a nuclear power station at Sizewell C.

  9. First published.