Opposition to Sizewell C Nuclear Power Station sea defence plans lodged

The claim comes after it emerged that developer Sizewell C Ltd had committed to potentially building additional flood barriers which weren’t included in the power station’s development consent order.

TASC has raised concerns that the construction of the additional barriers could disrupt nearby protected areas of wildlife and says other less invasive flood defence options were not pursued.

Development consent for the power station was granted in July 2022, with the plans including coastal flooding defences consisting of two stone revetment walls – sloped structures generally constructed near shorelines – and the power station being built on a raised platform of 7.3 metres.

These plans were based on a worst-case scenario for sea levels rising, and included provisions for the height of the revetment walls to be increased should the risk of breaching the existing sea defences exceed a certain level.

However, an April 2024 report by the Office for Nuclear Regulation (ONR) revealed that the raised platform and two revetment walls would not be sufficient to protect Sizewell C in a worst-case scenario.

The report showed that Sizewell C Ltd had made provisions to build two more flood barriers, standing at nine and 10 metres high, further inland to protect the power station.

The report also revealed that this information had been known since 2015, when Sizewell C Ltd’s shareholder EDF produced a report on plans for the power station.

This report stated that a raised platform of 7.3 metres would not be sufficient in a worst-case scenario for sea levels rising, and either a higher platform or further flood barriers would be required to help protect it.

TASC says that there is clear potential for the additional barriers to impact nearby areas of wildlife such as the Minsmere–Walberswick marshes, which is a designated special area of conversation, and that the option for a less invasive flood defence measure of a higher platform was discarded.

In March 2025, TASC made a request to Ed Miliband MP, the Secretary of State for Energy Security and Net Zero (SoS), asking that he consider revoking or changing the development consent order to allow the environmental impacts of the project, including any additional overland flood barriers that would be required, to be re-assessed.

However, this request was not accepted by the Minister acting on behalf of the SoS. Now, TASC has submitted an application for judicial review of this decision on the following grounds:

• The SoS was in breach of his obligations under the Habitats Regulations Act 2017 when refusing TASC’s request to review the development consent order.
• The SoS misdirected himself in law in the wording of the response to TASC’s request.
• The SoS breached his duty of inquiry in his refusal of TASC’s request.
• The decision to refuse TASC’s request to vary or revoke the development consent order was irrational.

Chris Wilson, on behalf of TASC, said:

“Worried about Sizewell C’s 4,000 tonnes of spent nuclear fuel being stored on one of Europe’s fastest eroding coastlines until 2160, TASC and others raised concerns about the risk of the sea surrounding the site and flooding from the unprotected rear of the nuclear platform, but these fears were casually dismissed during the dwevelopment consent order (DCO) examination. However, our FOI request revealed that, for the chosen 7.3m AOD nuclear platform height, the risk of flooding from the rear of the site in a credible maximum climate change scenario was known to be true by EDF for several years before the DCO application was submitted.

“We must not let the Secretary of State of the Department for Energy Security and Net Zero allow Sizewell C Ltd to use the unpredictability of climate change to defer for decades the assessment and public scrutiny of the impacts of these two huge overland flood barriers. To our eyes, Sizewell C Ltd clearly 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. The effect of these additional barriers on the Sizewell community and the neighbouring ecologically sensitive sites needs to be assessed now. If left unaddressed, this could be a major burden on 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.”

Leigh Day solicitor Rowan Smith, who represents TASC, said:

“The revelation that further flood defences at Sizewell C have been contemplated, that these could harm local wildlife, and that less environmentally invasive options were not explored, is a cause of concern for our client. We are arguing that the plans for the additional flood barriers have evaded the necessary environmental assessments, and our client is calling on the Secretary of State to, at the least, review the development consent order for Sizewell C.”

Campaigners at TASC are supporting their legal campaign through crowdfunding.