Centrica (LSE:CNA) has agreed a Contract for Difference strike price of £70.50 per megawatt-hour for Sizewell B, covering the period from April 2035 to March 2055, with the price set in 2025 terms and indexed to CPI inflation.
The energy group, which holds a 20% stake in the UK's operational nuclear fleet through a partnership with EDF Energy, said the regulated framework removes exposure to merchant power prices and supports a fair return on a life extension investment of approximately £800 million.
The investment is expected to be funded entirely through operating cash flows generated by the existing nuclear partnership over the next 15 years, with no requirement for additional equity.
"Sizewell B is critical to delivering the reliable, zero-carbon baseload power that supports Britain's energy security, protects skilled jobs and underpins a more resilient economy," said Chief Executive Chris O'Shea.
The contract with the UK government is expected to be finalised later this year.
Centrica has been building out its nuclear exposure beyond the existing fleet. In July 2025 it acquired a 15% stake in the 3.2GW Sizewell C development for a phased investment capped at £1.3 billion, and in September 2025 signed a joint development agreement with X-energy for a proposed advanced modular reactor programme targeting 6GW of capacity across the UK.
