Energy Secretary Edward Davey insists that there will not be a direct subsidy of new nuclear, but cannot say the cost will not end up with the taxpayer or consumer.
He says that the Horizon deal with Hitachi is "a real vote of confidence from foreign company" in the UK.
Spades will be in the ground at Oldbury and Anglesey in 2016 or 2017 at the very earliest.
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The PM promises to double to 200,000 the number of homes built under an existing scheme aimed at easing Britain's housing shortage.
The Met Office has weather warnings in place for snow and ice until 10am in the north and west.
The plan, which would effectively strip banks of the benefit of recent corporation tax cuts, forms part of the party's election manifesto.