On behalf of 15,000 scientists, engineers and specialists in nuclear companies, the professional union Prospect said the venture by E.On and RWE npower bodes well for the future of the nuclear construction programme.

Mike Clancy, Deputy General Secretary, said: “It is good news for UK plc and suppliers that the generators are seeking an integrated approach to nuclear new build. This work needs to be co-ordinated if we are to avoid the prospect of wasteful competition for new-build sites and skills.”

Clancy said staff would be keen to find out any implications of the joint venture for existing employees in the two companies, and whether the venture would be backing a single reactor design.

The Generic Reactor Design Assessment process now under way requires the Nuclear Installations Inspectorate to decide between the two designs for new reactors still on the table: the AREVA European Pressurised Reactor (EPR) and the Toshiba Westinghouse AP1000.

Either choice will create a multi-billion pound investment opportunity for the UK and many thousands of high quality, sustainable jobs, said Clancy, in addition to cutting carbon emissions and enhancing energy security.