Regulators have approved the design for nuclear reactors put forward by EDF and Areva as suitable to be built in Somerset.
The move marks the end of a five-year, £35 million "generic design assessment" process by the Office for Nuclear Regulation (ONR) and the Environment Agency to assess the companies' UK EPR reactor for use in the UK.
French energy giant EDF, which has proposed building the first of the UK's planned new generation of nuclear plants at Hinkley Point, Somerset, welcomed the announcement as a "major achievement and milestone".
The regulators have secured 82 design changes to improve safety and security, including a number brought in following the Fukushima disaster in Japan, when nuclear reactors went into meltdown after a massive earthquake and tsunami.
These include additional flooding protection for electricity supplies and provision of mobile pumps and generators and places to plug them in.
It does not mean construction can begin at Hinkley Point, as site specific construction consents and environmental permits are still needed, along with a planning decision by Energy Secretary Ed Davey that is expected by March next year.
The project is also subject to EDF's final investment decision on whether to go ahead with building two new reactors at Hinkley Point.
But regulators believe approving the generic design for the type of reactor is a "significant step" in constructing a new nuclear plant.
Completing the assessment while the designs are still on paper will prevent changes having to be implemented during construction when it would have been more costly, difficult or time-consuming, officials said.
Colin Patchett, acting chief inspector of nuclear installations at the Office for Nuclear Regulation, said: "We are satisfied that this nuclear reactor is suitable for construction in the UK.
"It is a significant step and ensures that this reactor meets the high standards that we insist upon. We have been able to identify significant issues while the designs are on the drawing board.
"There remain site specific issues that must be addressed before we'll approve its construction on any site."