The government has been in negotiations with French-owned EDF Energy over the Hinkley Point C project for more than a year.
Ministers are believed to have agreed on a "strike price" - the rate to be paid for electricity produced at the Somerset site.
It comes as a new poll revealed almost one in four Scottish households are worried about how the UK will generate enough energy in five years time.
The IPSOS Mori survey of 2000 people for the Energy Saving Trust revealed 23% think it will be difficult to supply enough energy to meet the UK's needs by 2018.
Chancellor George Osborne removed another obstacle last week when he announced Chinese firms will be allowed to invest in UK civil nuclear projects - even potentially taking a majority stake.
The two reactors proposed for Hinkley are a key part of the coalition's drive to shift the UK away from fossil fuels towards low-carbon power.
Energy policy has shot up the agenda since the party conference season, when Labour leader Ed Miliband pledged to freeze retail prices for 20 months.
The issue has become even more controversial with the Big Six power firms unveiling hikes of more than 9% in electricity and gas prices.
The Archbishop of Canterbury Justin Welby and Deputy Prime Minister Nick Clegg have both raised concerns about the hikes.
Mr Welby said in a Sunday newspaper companies had to be "conscious of their social obligations".
Mr Clegg demanded more evidence that the hikes were needed at all.