The plan to press ahead with Hinkley Point C, a huge infrastructure project that will deliver 7 per cent of the UK's electricity needs, has the strong political backing of David Cameron, the UK prime minister, and the leaders of France and China.
It will be the commercial centrepiece of Mr Xi's visit this week. A second Chinese nuclear group, CNNC, will be involved in the project as a joint venture partner.
The agreement means that Hinkley will get a new completion date of 2025, coming online a decade from now and two years later than planned. It is already well behind schedule after a lengthy EU state aid inquiry, protracted talks on investment and the near failure of France's Areva, which will supply the European Pressurised Reactor technology used in the plant.
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EDF expects Hinkley's construction to be funded initially by equity.
Industry insiders say this means it is unlikely to raise as much debt as envisaged originally and is, therefore, not expected to draw heavily on public funds to underwrite that debt. The Treasury last month agreed to provide a £2 billion infrastructure guarantee. While more funding may be available, EDF has no plans to request it.
This week's accord is also expected to include a reference to future co-operation with the Chinese on two further nuclear plants, Sizewell in Suffolk and Bradwell in Essex.
China wants to use Bradwell to showcase its own reactor technology and would take the lead on that project, submitting a design to UK regulators.
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"Hinkley opens the way for them to submit their own designs and proposals," said one industry insider.
A poll commissioned by Greenpeace on Monday showed that less than a third of the UK public backed plans to build a new reactor at Hinkley. Some 29 per cent of more than 2,000 surveyed supported the plans, against 34 per cent opposed. "George Osborne is about to plough billions into the bottomless pit of ever more expensive nuclear power whilst pulling the plug on clean energy sources that are getting cheaper every year," said Doug Parr, the environmental campaign group's chief scientist.