French energy firm EDF will extend the life of four of its eight nuclear power plants in the UK.
The move will safeguard 2,000 jobs and help with tight energy supplies.
Heysham 1 and Hartlepool will have their life extended by five years until 2024, while Heysham 2 and Torness will see their closure dates pushed back by seven years to 2030.
Meanwhile, EDF said its 2015 profits fell 68% to €1.18bn mainly due to writedowns on coal-fired plants.
The results were below analysts' expectations.
The value of plants in the UK, Italy, Poland and Belgium fell, and the company also took charges on its Edison oil and gas exploration business.
EDF will cut its dividend by 15 cents to €1.10 a share with an option for payment in new shares rather than cash.
Its shares have fallen almost 25% since the start of the year.
EDF said its decision to extend the life of its plants followed "extensive technical and safety reviews".
Chief executive Vincent de Rivaz said: "Our continuing investment, our expertise and the professional relationship we have with the safety regulator means we can safely prolong the operating life of our nuclear power stations.
"Their excellent output shows that reliability is improving whilst their safety and environmental performance is higher than ever."
The four nuclear plants employ about 2,000 permanent staff and 1,000 contractors.
They provide electricity to about a quarter of the UK's homes.
The announcement comes amid concern about the amount of energy available to keep the lights on, due to the closure of many of Britain's ageing power plants.
Meanwhile, EDF has yet to finalise the investment for a new nuclear plant to be built at Hinkley Point in Somerset.
It has agreed a deal in principle under which China General Nuclear Power Corporation (CGN) will pay a third of the cost of the £18bn project in exchange for a 33.5% stake.
An EDF board meeting to approve the plan earlier this year is thought to have been postponed. Reports suggested the company was struggling to find the cash for its 66.5% stake.
The company said on Tuesday: "Hinkley Point C is a strong project which is fully ready for a final investment decision and successful construction. Final steps are well in hand to enable the full construction phase to be launched very soon."
However, Paul Dorfman of the UCL Energy Institute, told BBC Radio 4's Today programme: "Unfortunately, with the best will in the world, it may just not happen. Chris Bakken, the man charged by EDF to construct Hinkley Point, has quit to spend more time with his family, EDF shares have crashed to half their value a year ago; the budget for Hinkley alone is bigger than EDF's entire market value.
"Areva - EDF's construction arm - has been bankrupted by the huge costs and time overruns for the same brand of reactor they want to build at Hinkley, so it seems there's a good chance that it simply may not happen."