Sellafield: nuclear regulation
How the Environment Agency regulates discharges and radioactive waste disposals from Sellafield through environmental permitting.
Applies to England
Sellafield nuclear site is one of the most complex and hazardous industrial sites in Europe. Activities carried out at the site include:
- retrieving waste from old (legacy) facilities
- cleaning up (decommissioning) redundant buildings
- receiving and storing spent nuclear fuel, including from the UK’s Magnox and Advanced Gas Reactor (AGR) nuclear power stations
- safely managing and storing nuclear materials and radioactive waste
The site is operated by Sellafield Ltd. Sellafield Ltd publishes incident reports and notices.
The Environment Agency regulates Sellafield Ltd with the Office for Nuclear Regulation (ONR).
The two nuclear regulators provide reports to the West Cumbria Sites Stakeholder Group. This is an independent body whose role is to provide public scrutiny of the nuclear industry in west Cumbria.
Find out more about how the Environment Agency regulates nuclear sites.
Regulating through environmental permits
Nuclear sites must have an environmental permit to operate. Through the environmental permitting process, the Environment Agency regulates Sellafield’s radioactive discharges to air and water, and solid radioactive waste disposals.
Environmental permits contain strict conditions (rules) an operator must follow. These conditions are designed to make sure that the operator’s activities do not harm people or the environment.
The Environment Agency sets stringent discharge limits in Sellafield Ltd’s environmental permit. It makes sure the company minimises discharges and their impacts on people and the environment.
You can ask to see a copy of Sellafield Ltd’s current environmental permits in the public register.
Reviewing Sellafield Ltd’s environmental permits
In July 2022 the reprocessing of spent nuclear fuel ended at the Sellafield site. Sellafield Ltd is now focusing on decommissioning the site and safely managing and storing radioactive waste and nuclear materials. As a result, discharges into the environment have and will reduce.
In 2018-19 we carried out a major review of Sellafield Ltd’s radioactive substances activity (RSA) permit. This permit controls the receipt and disposal of radioactive waste. It also sets conditions and limits on the discharges to air and water. This was the most significant review of this permit since the early 2000s.
As part of the permit review, Sellafield Ltd applied to vary (change) its RSA permit in October 2018. We consulted on this application in 2018 and again on our draft decision in 2019.
We reached our final decision on Sellafield Ltd’s proposed changes, incorporating comments received from both consultations.
Sellafield Ltd applied to vary (change) the RSA permit again in 2020 and 2021. We reached our decisions after consultation.
The latest permit variation was issued in October 2023 following consultation. Read the decision document. The changes include:
- registration of a new stack on the Magnox Swarf Storage Silos facility that allows an improvement to gaseous abatement
- registration of a new outfall to the River Calder for construction related aqueous waste arisings
- removal of limits for 2 radionuclides that are no longer discharged from the site
- reduction to the radium-226 limit and update to the site plan due to Sellafield Ltd’s application to extend the Calder Landfill Extension Segregated Area (CLESA) into an adjacent ‘valley area’ (this will not result in any changes to the environmental permit site boundary)
Sellafield Ltd also holds an installation environmental permit. We are planning to carry out a wider review of this permit in 2024 as operations change on site.
Magnox Swarf Storage Silo (MSSS) facility leak
There is an ongoing leak of radioactive liquid from the MSSS facility at Sellafield into the ground. Sellafield Ltd estimate that the leak started in July 2019. They formally reported it to the Environment Agency in November 2019.
The cause of the leak is believed to be reopening of historical cracks in the facility structure that caused leakage to ground in the 1970s. When the leak resumed in 2019, its rate initially increased up to around 2,400 litres per day. It has stabilised at this level since October 2020.
We expect the leak to result in significant long-term consequence due to additional radioactive contamination of the ground and groundwater at Sellafield. This will need to be addressed in the clean-up of the site, with potentially significant implications for:
- nuclear liabilities
- the quantities of low and intermediate level waste resulting from the site clean-up
Based on the current understanding of the leak, we conclude that any risk to the off-site environment and public:
- is expected to be very low
- would be realised over an extended timescale
There is:
- no risk to public water supply boreholes from the leak
- no risk of drawing any contaminated groundwater towards these boreholes
We have classified the leak as category 1 (major) on our compliance and common incident classification schemes because of the long term consequence.
The Environment Agency’s formal investigation into the resumption of the leak resulted in a warning letter to Sellafield Limited in July 2022. The continued leakage represents an ongoing non-compliance with the permit. We recognise that there are significant challenges in addressing the leak because of the nature of the facility and its location. Therefore our regulatory focus is on working with Sellafield Ltd to ensure an effective and timely plan is implemented to address the leak.
As part of our regulatory response, in March 2021 we issued a series of improvement requirements for the MSSS (as part of a further variation to the permit).
The improvement requirements in the permit require action to tackle the MSSS leak. They aim to:
- stop or minimise the current leak and its consequences
- minimise the potential for further below ground leaks in the future
In July 2023 Sellafield Limited provided us with its detailed plan to meet these improvement requirements. The plan includes decisions to be taken on:
- how and when to retrieve waste from the silos
- possible implementation of measures in the silo and in ground to reduce the consequences of the leak
We assessed the plan and agreed to its delivery on 4 December 2023. Sellafield Limited is now required by conditions we introduced into its permit in response to the leak to implement the plan.
The Environment Agency is working closely with ONR in response to the leak. You can read ONR’s report about the MSSS leak.
Read Sellafield Ltd’s case study about the MSSS.
Monitoring radiation from Sellafield
An environmental permit requires operators to monitor radiation levels from their discharges and any effects on the environment.
Sellafield Ltd carry out environmental monitoring around the Sellafield site. The Environment Agency assesses the results and suitability of Sellafield Ltd’s programme, including the company’s monitoring for radioactive objects on beaches in West Cumbria.
Find out more about:
- monitoring beaches near Sellafield
- Sellafield Ltd’s environmental monitoring
- Public Health England’s Assessing the risk to people’s health from radioactive objects on beaches around the Sellafield site - summary report
The Environment Agency has also developed a Sellafield radioactive objects notification and intervention plan with other organisations involved in protecting the public. This plan explains how the different organisations will work together to:
- protect the public and environment from any harm caused by radioactive objects on west Cumbria beaches
- respond to a discovery of radioactive objects near the Sellafield site – a significantly unusual single find or a significant overall change in the find rate, activity or trends
- check that the conclusions of a public health risk assessment for the radioactive objects are still valid
Monitoring the environment for radioactivity around nuclear sites is also done independently by the Environment Agency and other regulators. Find out more about monitoring radioactivity in the environment.
Contact Nuclear Regulation Group (north)
Updates to this page
Last updated 10 January 2024 + show all updates
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Updated information about our reviews of Sellafield Ltd’s environmental permits. Updated information about the Magnox Swarf Storage Silo (MSSS) facility leak. Added a link to Sellafield Ltd's incident reports and notices.
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Updated to include information about the permit variations V009, V010, V011 and V012.
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Updated to reflect changes to environmental permits.
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We have removed the text: 'introduce a specific tritium limit for solid waste disposals at the on-site landfill – known as the Calder Landfill Extension Segregated Area'. This has not been implemented yet.
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Following public consultation, we have published our decision on changes to Sellafield Ltd's radioactive substances activities permit.
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Updates on the consultations about proposed changes to Sellafield Ltd's radioactive substances activities (RSA) permit. Also updated to include information about the review of Sellafield Ltd's installation permit.
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First published.