Four nuclear power reactors in the UK have been granted extensions by their owner, propping up government efforts to decarbonise the grid.

Centrica and EDF are increasing the lifespan of their Advanced Gas-cooled Reactors (AGR) at Heysham 1 and Hartlepool until March 2027, one year later than previous expected, according to a statement on the London Stock Exchange on Wednesday.

Heysham 2 and Torness are also being kept open by an additional two years, generating electricity until March 2023.

Centrica said the extensions would add around nine TWh to both company’s electricity generation between 2026 and 2030.

Ministers see nuclear power as vital to hitting looming emissions targets, given wind and solar power projects are reliant on specific weather conditions.

“At a time when energy security is uppermost in people’s mind, I’m delighted that we’re able to extend the operating window of the UK’s nuclear fleet, which is critical to UK security of supply and the country’s net zero ambitions,” Chris O’Shea, Centrica chief executive, said.

“In an energy system that is becoming ever more intermittent, baseload power generation that doesn’t depend on the sun shining and the wind blowing is essential to keeping the lights on.”

The decision was taken after an extensive review process which sought to determine whether the lifespan of the power stations could be increased without compromising safety.

Ongoing reviews could lead to further extensions, Centrica, which owns a 20 per cent stake in the sites, added. The current dates are forecasts, with precise dates determined in future following regular graphite inspections by the plants’ operators and the Office for Nuclear Regulation.

“There is no silver bullet that will achieve net zero, but a diversified energy system underpinned by nuclear power is a positive further step towards a greener, fairer future,” O’Shea said.

EDF is expected to spend a further £1.3bn on its nuclear arsenal from 2025 to 2027, having already invested around £8bn over the last 15 years. Sizewell B was kept out of the most recent review process as it is a different type of power station; however, its lifetime could be extended by two decades to 2055.