Sizewell nuclear plant extended as part of UK’s net zero push
Suffolk facility started running in 1995 and remains Britain’s most recently built nuclear installation
The UK has guaranteed the price of Sizewell B nuclear power station’s electricity for two decades until 2055, a move that will potentially make it one of the world’s longest-serving nuclear plants.
The Labour government is trying to boost the quantity of nuclear power to back up wind and solar supplies, which are increasing as the country tries to cut carbon dioxide emissions to net zero by 2050.
Sizewell B, located in Suffolk, south-east England, supplies about 3 per cent of Britain’s electricity. All Britain’s other existing nuclear plants are due to shut by spring 2030, with replacements Hinkley Point C and Sizewell C due to come online in 2030 and the late 2030s, respectively.
Ministers said on Wednesday that heads of terms for Sizewell B had been reached on the arrangement, which will enable about £800mn of investment into the upkeep of the power station by EDF, the French state-owned owner and operator of the plant, and FTSE 100 group Centrica, which has a 20 per cent stake.
Lord Patrick Vallance, minister for science, innovation, research and nuclear, said the deal would “protect bill payers and boost the country’s energy security”, adding it would help maintain 900 skilled jobs.
The plans will need to clear regulatory hurdles. The Office for Nuclear Regulation, Britain’s nuclear regulator, said while life extensions did not require “formal regulatory assessment”, they needed to be done “under a valid safety case”.
“Safety cases at Sizewell B are likely to require updating to achieve EDF’s stated ambition, together with investment in plant to sustain equipment reliability, all while ensuring that the necessary people and skills are available throughout the extended lifetime,” the spokesman added.
Under the terms of the planned financing deal with the government, EDF will sign a “contract for difference”, under which the power station will receive £70.50 per megawatt hour, indexed to inflation, for the 20 years between 2035 and 2055.
Under the contract, if the price the station sells its power for in the wholesale market is lower than £70.50 per MWh, consumers will top up the difference. If it is higher, the station will have to pay back the difference.
The agreed price is lower than current wholesale power prices, which are high partly due to the disruption to energy markets caused by the Iran war, and lower than the fixed price awarded to the new Hinkley Point C nuclear power station that EDF is building.
However, it is above average wholesale prices of about £50 per MWh in the years before the energy crisis of 2021 to 2023.
Sizewell B started operating in 1995 and is the most recent nuclear power station to be built in Britain. If it continues until 2055 it will be one of the longest-running nuclear power stations alongside peers such as Nine Mile Point Unit 1 that opened in New York state in 1969.
It is the UK’s only pressurised water reactor among Britain’s current nuclear fleet. The rest are all advanced gas-cooled reactors.
Sizewell B’s successors, Hinkley Point C and Sizewell C, now being built by EDF and partners in Somerset and Suffolk, respectively, will also use more modern variants of the pressurised water technology.
Britain’s nuclear power stations supplied about 12 per cent of its electricity in 2025, helping to support a rapidly changing system in which intermittent wind supplied nearly 30 per cent, more than gas at nearly 27 per cent.