Together Against Sizewell C (TASC) is a community-based group of like-minded individuals who have been actively campaigning on a voluntary basis, since 2013, to stop the Sizewell C project.

TASC urgently need your help in our battle against the environmentally damaging Sizewell C project. We have discovered that the project now includes a stated commitment by Sizewell C Ltd to the Office for Nuclear Regulation (ONR) to install additional sea defences in a 'credible maximum' climate change scenario. These defences in the form of two huge 10 metre high ‘overland flood barriers’ were not included in the approved DCO project. In our opinion, these flood barriers, if installed, will likely have additional adverse impacts on the neighbouring designated wildlife sites including RSPB Minsmere as well as the Heritage Coast and Suffolk Coast & Heaths National Landscape. We need to ensure that the original promotor EDF and the now UK government controlled Sizewell C Ltd are not allowed to use climate change uncertainties as an excuse to delay assessment and avoid public scrutiny of these additional structures for decades. The full impact of the whole project should be assessed now.

Above picture taken from ONR’s External Hazards Proportionate Reassessment report May 2024 which first drew TASC’s attention to the overland flood barriers.

There is very little detail about the barriers, but it appears from the above diagram that, if needed:-

The Southern barrier stretches for nearly 500 metres from the Sizewell A site, across the Sizewell Gap to the start of the cliffs running south to Thorpeness, sited on land not in Sizewell C’s ownership.

The Northern barrier potentially stretches from the north of the Sizewell C site, through the SSSI, then inland over Goose Hill for up to a kilometre.

Together with our lawyers, Leigh Day, we have sought the High Court’s permission to apply for judicial review of the decision of the Secretary of State to refuse TASC’s request to revoke or vary the Sizewell C DCO. The grounds for our legal challenge are set out in Leigh Day’s press release.

To cover our legal costs to get to a High Court hearing, TASC urgently needs to raise £20,000. We are extremely grateful to all those  who are able to contribute and/or share details of our fundraiser with others.

How we got here

From documents obtained under a Freedom of Information (FOI) request, TASC found out that EDF knew as far back as 2017 that their chosen nuclear platform height of 7.3m AOD would, along with the adapted sea wall on the eastern flank of the site, require two 10-metre high ‘overland flood barriers’. These will be needed to prevent the nuclear platform from flooding from the west in the event that sea level rise reaches a ‘credible maximum’ scenario. This will lead to a major breach of the low-lying coast to the north of Sizewell C and south of the Sizewell nuclear cluster. However, while EDF rightly included the adaptive design of the eastern sea defences in their DCO application documents, they did not include the southern and northern overland flood barriers in the DCO application, thereby avoiding any public scrutiny. As a result there is no commitment in the approved DCO to install these additional sea defences. This is despite there being a requirement to keep the nuclear site safe for its full lifetime from climate change impacts in a credible maximum scenario i.e. to, at least, 2160 while spent nuclear fuel is stored on site.   

TASC’s aim is to ensure that the overland flood barriers, not included by EDF in the DCO application, now form part of the overall project. Therefore we need the Secretary of State to either revoke or change the DCO, in order that a lawful assessment of the potential environmental impacts of the entire project is carried out and subject to public scrutiny. 

This is important because the project may be grossly underestimating the potential environmental impact, flood risk and sea-defence costs. This, if unaddressed, could be a major burden on future and far future generations who may be impacted by severe, non-reversible environmental, ecological and human impacts combined with an extreme financial liability if Sizewell C were to flood.

Further background for those that want to know more

The Sizewell C project, originally promoted by EDF, is to build twin EPR nuclear reactors close to the North Sea at Sizewell, Suffolk, one of the fastest eroding coastlines in Europe. The site is in the heart of Suffolk Coast & Heaths National Landscape, largely surrounded by designated wildlife sites including RSPB Minsmere and will be partially built on Sizewell Marshes SSSI.

In 2021, Prof Paul Dorfman’s report stated “…any adaptation efforts to mitigate annual flooding (projected to almost entirely surround the proposed EDF Sizewell C EPR nuclear island by 2050) will inevitably entail significantly increased expense for construction, operation, spent nuclear fuel management, rad-waste storage and eventual decommissioning”. 

In line with the ONR’s preference, Hinkley Point C is a ‘dry site’ i.e. its platform height at 14 metres AOD is of sufficient height to prevent it from flooding. However, Sizewell C with a platform height of 7.3m AOD, is a ‘protected site’ which means that Sizewell C must at all times demonstrate that the site can be protected against flooding for its full lifetime by use of ‘permanent external barriers such as levees, sea walls and bulkheads’. Once Sizewell C is constructed with a 7.3m AOD platform height, the platform cannot be raised at a later date. The overland flood barriers need to be assessed now so alternatives can be considered e.g. raising the platform height.

Sizewell C was given DCO approval in July 2022 against the recommendation of the five professional planning inspectors. In TASC’s view, the impacts from the overland flood barriers, if they had been assessed during the DCO examination, may well have resulted in planning permission being refused. In any event, our case argues that the Secretary of State’s ‘Habitats Regulation Assessment’ has not considered the environmental impacts of the full project or alternatives, something that is a lawful requirement. 

Documentation published by the ONR supporting their grant of Sizewell C’s nuclear site licence in May 2024, has revealed that, in TASC's opinion, there are now two materially different projects, the one in the DCO approved by Kwasi Kwarteng, and the one still being considered by the ONR as part of the ‘site safety case’. It was an FOI request to the ONR in late 2024 that provided the documentation from 2017 that shows the project requires the adaptive flood protection in the form of the overland flood barriers in a credible maximum climate change scenario.

The Sizewell C site will be storing up to 4,000 tonnes of spent nuclear fuel on this vulnerable coastline until the late 2100s. The precautionary principle should surely apply so resilience, potential risks and impacts are assessed on a worst case basis and that should be done now. Sizewell C Ltd seem to believe they can do as they see fit with our Heritage Coast, National Landscape and designated wildlife sites irrespective of the damage they will cause.

In an attempt to resolve our concerns, on 6^th March 2025 TASC wrote to Secretary of State, Ed Miliband calling on him to make a decision on whether the material change to the Sizewell C project highlighted by TASC, namely the commitment to install ‘overland flood barriers’, ‘amounts to exceptional circumstances that make it appropriate for him to exercise his power to change or revoke the DCO’.

The Energy Minister, on behalf of the Secretary of State, replied on 28^th March 2025, refusing TASC’s request to vary or revoke the DCO. As TASC consider this matter to be of great importance, we have been left with no alternative but to challenge the Secretary of State’s decision through the courts.

Aerial view May 2025, of Sizewell C’s main development site where 22,000 trees have been felled

Those that live in the Sizewell area or know it well are only too aware that Sizewell C has already caused extensive environmental damage prior to a final investment decision by the government  – sadly, Suffolk now has its own version of HS2! The UK government currently own 88% of Sizewell C with EDF owning the remaining share. To date, £6.4 billion of UK public funds have been committed  to the project. In our view, the lack of an assessment of the full project needs to be resolved before the government makes a FID which would involve committing further billions of public funds to Sizewell C.

To those, such as Keir Starmer, who like to use inflammatory language to call us ‘NIMBYs and blockers’, we say that we would not be in this situation if the developer had been open and transparent by including the overland flood barriers in the DCO application. In addition, this action may have been avoided if our concerns about this matter had been fully addressed when previously raised with the Dept. for Energy Security and Net Zero.

Thank you so much to all those supporting our campaign.

(Note: hyperlinks to supporting documentation are provided in the list of Annexes in the above referenced letter of 6th March 2025 to Ed Miliband)