British Gas owner Centrica PLC (LSE:CNA) hailed the one-year life extensions of the Heysham 1 and Hartlepool nuclear power stations, where it holds a 20% stake.
Both plants are now expected to operate until March 2028, with the extensions expected to add three terawatt-hours (TWh) of electricity generation between 2026 and 2030.
Including other life extensions announced since December, the FTSE 100 company's nuclear power portfolio has added a projected 60 TWh, or 12 TWh for Centrica.
Centrica also recently invested £1.3 billion for a 15% stake in the Sizewell C nuclear project that is under construction in Suffolk.
The four nuclear stations in Centrica’s portfolio generate electricity to power more than 4 million homes a year.
Chief executive Chris O'Shea said: "The UK needs more reliable, affordable, zero-carbon electricity, so the extension of Heysham 1 and Hartlepool is great news.
"We believe in having a diversified energy system, with nuclear power playing a key role in ensuring stability and sustainability for decades to come."