The Sizewell C project has received another £170m from the government's war chest that was announced last year to get work underway on the Suffolk coast.
The money will be used to continue preparatory work at the site of the proposed twin-reactor power station.
And it will enable the partners to continue with the drawing up plans for the huge plant.
The money comes from the £700m that was pledged to the project last winter when the government took a 20% stake in Sizewell C.
A spokesman for the project, which is led by French government-owned EDF, said: “This is another big endorsement of Sizewell C and will put us in an even stronger position to begin full construction.
"As well as continuing with site preparation, we are bringing forward funding for some local community projects.
"We are excited by the growing momentum in the project and looking forward to seeing the positive impact it will have for people in East Suffolk and in the rest of Britain.”
However opposition groups felt the government should have the courage to cut its losses and walk away from the project.
Alison Downes from Stop Sizewell C said: "It sticks in the throat to see Ministers splashing more taxpayers' cash months before a Final Investment Decision, while maintaining total secrecy about whether Sizewell C can achieve value for money.
"With an Office for Nuclear Regulation Inspector calling Sizewell 'an expensive site to develop', and Vattenfall's Boreas offshore wind farm falling victim to 40% cost increases, when will Ministers come clean about the true cost of Sizewell C?"
Work has already started on part of the site while local conservation groups including the RSPB at the nearby Minsmere nature reserve continue to raise concerns.
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