Plans for a new generation of nuclear power stations in the UK have reached a "huge milestone", after regulators approved the design of reactors.
Horizon Nuclear Power wants to use a new Japanese-American design for its £12bn Anglesey power project, and at Oldbury-on-Severn in Gloucestershire.
Regulators are satisfied it meets "expectations on safety, security and environmental protection".
It paves the way for planning applications for Wylfa Newydd in 2018.
The design of the joint Hitachi-GE advanced boiling water reactors has been under scrutiny since 2012.
The findings of UK regulators will be used by the company as part of its environmental permit applications for the new Wylfa Newydd plant.
Horizon plan to ask the UK government for a development consent order to build the Anglesey power station in the first quarter of 2018.
Natural Resources Wales, the Environment Agency and the Office for Nuclear Regulation have all been involved in the "in-depth assessment" of the Hitachi-GE's reactor design.
Duncan Hawthorne, Horizon chief executive officer, said: "This is a huge milestone for Horizon and a major leap forward for us in bringing much-needed new nuclear power to the UK.
"Nuclear can deliver high volumes of stable low carbon energy, which makes it a vital part of the country's electricity mix and once up and running, both Wylfa Newydd and our Oldbury site will supply clean, reliable power to the UK for decades to come."
The decision has also been welcomed by Albert Owen, MP for Ynys Môn.
He said the approved of the reactor design was a "significant milestone" and he was pleased it has "met the very high standards of safety required by UK regulators".