The lifespan of Scotland's last remaining nuclear power station and three other plants in England are to be extended.
EDF Energy says Torness, in East Lothian, and its sister site Heysham 2, in Lancashire, will continue generating for an extra two years until 2030. Two other sites - Hartlepool and Heysham 1 - will continue for an extra year until 2027.
The French state-owned company says it will now invest £1.3billion across its operational nuclear estate over the next three years.
Torness began generating electricity in 1988 and was originally due to be decommissioned last year.
The four power stations support around 3,000 workers and can generate up to 4.6 gigawatts of electricity - enough to power about 4.5 million homes.
The extensions will support the UK's baseload power generation for years to come, support the UK's net zero ambitions and help maintain grid stability at a time when cleaner, but more intermittent, renewable generation is being added to the energy mix.
Chris O’Shea, chief executive of British Gas owner Centrica, which also owns a stake in the four nuclear plants alongside EDF, said: "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.
"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.
"Today's extensions to the lives of the zero carbon Heysham 1, Heysham 2, Hartlepool and Torness nuclear power stations are a positive reflection of the valuable investment that Centrica and EDF have made in these plants.
"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. We're delighted that a further extension was possible which allows us the time necessary to develop other zero carbon dispatchable electricity generation options such as new nuclear and hydrogen fired generation. We must move at a faster pace to ensure that these replacement technologies are deployed in time."