The deal, for an undisclosed sum, sees NuGen – a joint venture between Toshiba and Engie – take responsibility for the site to the northwest of the Sellafield complex.
Detailed site characterisation studies will take place in the autumn and feed into detailed planning for the three-reactor nuclear power station.
NuGen chief executive Tom Samson called the agreement a “major milestone” and a “key moment in our Moorside project journey”.
He added: “Our board has reached a decision of significance which confirms Moorside is suitable, against criteria at this stage of the development. NuGen, our vendors and our expert partners are all confident we can build three reactors on the site.”
The GMB union also welcomed the deal as “a positive step forward” but national secretary for energy Gary Smith warned “there is a long way to go” and “huge hurdles still to overcome”.
He added: “It is important that government throws its weight behind the project to build an integrated future for the nuclear industry in West Cumbria.”
Energy minister Andrea Leadsom said new nuclear “is a key part of our long-term plan to power the economy with clean, secure energy and keep bills as low as possible for hardworking families and businesses”.
She added: “Moorside will be a major infrastructure project that creates jobs and economic security for thousands of people and helps to deliver the Northern Powerhouse.”