Sizewell B to run until 2055 under 20-year £70.50/MWh contract

The contract

The contract for difference runs for 20 years, from April 2035 to March 2055. The plant had been due to close in 2035.

It guarantees a set price. When wholesale power falls below it, billpayers make up the gap. When the market rises above it, the operator pays the surplus back.

The strike price of £70.50 per megawatt-hour in 2025 prices fixes the plant's revenue for two decades.

Investment and jobs

Sizewell B supplies about 3% of Britain's electricity and supports roughly 900 jobs in Suffolk.

About £800m will go into modernising the plant, mostly from EDF with 20% from Centrica, matching Centrica's share in EDF's UK reactors. The work includes a plant monitoring system, the kind now going in at Hinkley Point C and Sizewell C, plus upgrades to valves, pumps and pipelines. The extension takes Sizewell B to a 60-year operating life.

Lord Patrick Vallance, minister for science, innovation, research and nuclear, called extending a nuclear plant's life "a normal thing to do".

Centrica chief executive Chris O'Shea said the deal "gives Sizewell B a clear, regulated framework through to the 2050s".

How the price compares

The strike price is below the £91.20 per megawatt-hour the government agreed for new offshore wind farms earlier this year. It is also more than £10 below the previous Sizewell B contract. Ministers estimate consumers would have saved around £2bn had the plant run under this model during the price spike that followed Russia's invasion of Ukraine.

EDF calculates that Sizewell B's output to date is 270 terawatt hours, enough to power every home in the UK for almost three years.

The plant and its workforce

Sizewell B has run since 1995. It is the UK's only pressurised water reactor and produces 1.2 GW, about nine terawatt hours a year, enough for roughly 2.5 million homes.

EDF employs 620 staff and about 300 contractors at the plant.

Robert Gunn, the station director, said the extension "safeguards existing jobs and allows us to continue to recruit another generation of Suffolk young people for the nation's nuclear renaissance". The plant runs a planned two-month outage every 18 months for repairs. The current one was due to finish in the last week of July and was likely to cost around £80m.

Not everyone welcomed the deal. Chris Wilson of the campaign group Together Against Sizewell C called the extension a "multi-generational financial and environmental liability".

The rest of the fleet

Four older stations are heading for closure. Hartlepool and Heysham 1 stop generating in 2028, and Heysham 2 and Torness in 2030.

Their replacements are years away. Hinkley Point C's two EPR reactors are expected around 2030, according to the American Nuclear Society, with the Guardian reporting a start in the early 2030s. Sizewell C, next to Sizewell B, would produce 3.2 GW, enough for about six million homes against Sizewell B's 2.5 million. The Guardian reported the government hopes a "golden age of nuclear" will meet growing demand from electric vehicles, low-carbon heating and AI datacentres.

What happens next

Final approval of the contract should come later this year. The Office for Nuclear Regulation said safety and security at any nuclear site "must be fully demonstrated to us as part of ongoing regulation". The upgrades will run over 10 to 15 years and take place during the plant's regular outages.