The estimated cost of constructing the 3.2GW Sizewell C nuclear power plant in Suffolk, England, has reportedly increased to £40bn, nearly double the initial projections by its developer, Electricité de France (EDF).
The revised figure, reported by the Financial Times, reflects 2025 prices and is attributed to rising construction costs and lessons learned from delays and overruns at EDF’s Hinkley Point C project in Somerset.
Sizewell C is a pivotal component of Britain’s strategy to achieve climate targets and strengthen energy security. Once operational, the facility, through its two EPR reactor units, is expected to generate enough electricity to power six million homes.
The Financial Times report cited a senior government official and two industry insiders who characterised the £40bn estimate as a reasonable projection. However, a spokesperson from the Department for Energy Security and Net Zero described the figure as “speculative” and emphasised that discussions with potential investors remain “commercially sensitive.”
Julia Pyke and Nigel Cann, joint managing directors of Sizewell C, refuted the claims in a statement, noting that the reported costs “do not reflect the significant savings we are already making because we are building on the achievements at Hinkley Point C.”
EDF declined to comment directly on the matter, reported Reuters.
France’s top audit authority, Cour des Comptes, meanwhile, urged EDF to secure new investors for the project before committing to additional financing. This recommendation adds further scrutiny to the financing model for Sizewell C, which has relied heavily on government backing and private sector participation.
EDF originally projected that Sizewell C would cost 20% less than Hinkley Point C due to efficiencies achieved during the latter’s construction.
In 2020, the estimated cost for Sizewell C was approximately £20bn. However, delays and cost increases at Hinkley Point C, whose budget now ranges between £31bn and £34bn, have highlighted the challenges associated with large-scale nuclear projects.
The Treasury is reportedly reviewing whether to provide additional financial support for the project in the upcoming spending review.
Last year, the UK government announced an investment of £1.3bn to support Sizewell C. The facility is majority-owned by the British government and EDF.
Sizewell C is projected to meet 7% of Britain’s energy needs over its 60-year operational lifespan. Alongside renewable energy sources, the nuclear plant aims to reduce the UK’s reliance on fossil fuels and protect households from volatile gas prices.
