The Government has given the go-ahead for the first of a planned new generation of nuclear power plants in the UK.
But construction of the first new nuclear reactors since the 1990s depends on a deal being struck between the Government and energy giant EDF over the price the company will get for electricity generated at the site at Hinkley Point, Somerset.
EDF said intensive discussions were ongoing on the guaranteed "strike" price for power generated at the plant, consisting of two reactors - which will supply enough electricity for five million homes.
Under electricity market reforms, low-carbon power such as nuclear reactors will have long-term contracts with a guaranteed price for their electricity, to give investors certainty to invest in projects with high capital costs.
The move to grant planning permission for Hinkley Point C was welcomed by unions and local councils in the region, who said it would generate tens of thousands of jobs and boost the economy.
But environmental groups criticised the Government for pressing ahead with new nuclear plants, warning that the price agreed for the electricity would be too high and raising concerns over the lack of plans for dealing with nuclear waste.
Energy Secretary Ed Davey said affordable new nuclear would play a "crucial role" in ensuring secure, diverse supplies of energy in the UK and decarbonising the electricity sector and the economy.
He said: "This planned new nuclear power station in Somerset will generate vast amounts of clean energy and enhance our energy security. It will benefit the local economy, through direct employment, the supply chain and the use of local services."
But Greenpeace executive director John Sauven argued that Hinkley Point C would lock consumers into higher energy bills, through a strike price which he said was expected to be double the current price of electricity.
And he warned: "With companies now saying the price of offshore wind will drop so much it will be on par with nuclear by 2020, there is no rationale for allowing Hinkley C to proceed. Giving it the green light when there is no credible plan for dealing with the waste could also be in breach of the law."