The controversial proposed Sizewell C twin reactor nuclear project in Suffolk is too slow, risky, expensive and damaging to help our climate and energy emergency. 

We urge UK Pension Funds and Insurers not to invest in Sizewell C.

Overview: EDF’s £30 billion Sizewell C is controversial for many reasons, including ESG concerns – see below. The EPR reactor type is largely unproven, expensive and has an inglorious track record for construction cost and time overruns. With EDF admitting a Final Investment Decision is not likely before late 2023 or even 2024, and a 10-12 year build, [1] Sizewell C would not be generating until at least the mid 2030s by which time the UK should  have completed its renewable energy transition. Rothschild & Co has said of gigawatt nuclear projects: “[Funds are] worried about what their employees and customers think. These are going to be big, high-profile investments that investors do not want to be controversial.” 

Risky technology and risky construction: All six EPR builds to date (of which only two are in commercial operation) are – or were – late and overspent. [2] Taishan I in China was offline for 12 months after fuel failure early in its operational life, and vibration issues remain unaddressed. It’s very unlikely France will ever build any more of this exact type of reactor, and is developing an ‘EPR2’. Hinkley Point C’s latest cost estimate is £26bn against £18bn at Final Investment Decision, and it will be a further 12 months late; Hinkley’s estimated cost and time have increased four time since construction began, and not all are related to the pandemic.

Risky Finance: It is widely accepted that Sizewell C will cost at least £30 billion. As consumers face the gravest cost of living crisis in living memory, the Regulated Asset Base or RAB funding model – essentially a nuclear stealth tax – will bring investors controversy and reputational risk and add to pressure on hard-stretched households. Research by the University of Greenwich Business School, using the government’s own RAB impact assessment, concluded that the financial impact on family energy bills during construction has been underestimated. Meanwhile, green levies on bills have been suspended, so how can the government justify adding a nuclear levy for Sizewell C?

Sizewell C is not needed: Multiple Future Energy Scenarios reach Net Zero without Sizewell C, including three out of five of the Climate Change Committee’s 6th carbon budget energy scenarios. A new study of the UK energy system by LUT University in Finland has concluded that the UK could reach net zero by 2050 and save well over £100 billion compared to the UK’s current strategy by pursuing a 100% renewable energy mix.

Controversial location: EDF claims replicating Hinkley Point C will help control ballooning costs, but it is impossible to replicate the location. Surrounded by  protected habitats, the Sizewell C site is considerably more complex, sensitive and difficult to access. Planning consent went against the Planning Inspectorate’s considered recommendation due to continued uncertainty about a secure potable water supply.

ESG Concerns: The intention of the Treasury to erroneously rebrand nuclear as ‘green’ would be highly controversial, and – as in the EU – likely challenged in the courts. 


  • Sizewell C would damage protected wildlife habitats and is opposed by both the RSPB, whose internationally famous Minsmere reserve adjoins Sizewell C, and the Suffolk Wildlife Trust. Part of Sizewell Marshes Site of Scientific Interest would be lost forever. The Sizewell C site is wholly within the Suffolk Coast & Heaths Area of Outstanding Natural Beauty.
  • Sizewell C is not sustainable. There is as yet no secure long-term potable water supply for the plant’s operation – requiring on average 2.2 million litres per day – in the driest region of the UK.
  • The cooling systems have the potential to trap and kill hundreds of millions of fish and other marine biota annually during each of its 60 years of operation.
  • There is still no long-term solution for the storage of toxic nuclear waste. A Geological Disposal Facility remains decades away and cost estimates are spiralling. Spent fuel from EPR reactors is hotter than other reactors and must stay on the eroding Suffolk coastline for a century. 

Social: There is considerable local opposition because of the impacts on communities, including:

  • An extra 12,000 vehicle journeys/day in an area with little road infrastructure. “Mitigating” bypasses are controversial, and EDF has refused to provide them ahead of construction.
  • The area lacks a sufficient workforce meaning an influx of 6,000 temporary workers.
  • Independent research found that tourists are likely to stay away in considerable numbers, resulting in a predicted income loss of £40m a year.


  • Sizewell C remains subject to Value for Money Assessments, which are not conducted in a transparent way.
  • There is still no information about what government considers to be the “correct” allocation of risk between consumers and investors, which is likely to be highly controversial.
  • Future ownership of Sizewell C is unclear. With its current owners, the UK Government and EDF – the latter heavily in debt and being re-nationalised – wanting no more than 20% of equity, future governance is very murky.
  • Regardless of who would own Sizewell C, as the only entity with experience of EPR reactors, EDF must build it. EDF is under considerable pressure in France with huge debts, half the domestic nuclear fleet offline in recent months due to corrosion issues, and President Macron wanting 6 new EPR2 reactors (a simplified version of the complex EPR). At what stage does EDF become too stretched to manage all its commitments?

Sizewell C would be highly controversial and risk reputational damage to investors

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  1. EDF’s Evidence to Science & Technology Committee, 2 November 2022
  2. Flamanville (France) and Olkiluoto (Finland) are over a decade late, still not in commercial operation and multiple times overspent.