“It is a very long and expensive road here,” he said, adding that “the next several months will be critical.”

Hitachi, without providing exact figures, wants government financing from Britain and Japan to help attract outside investors like pension funds that seek long-term income streams. Investments by the governments would also help lower Horizon’s risk rating.

The Wylfa Newydd plant, with two giant reactors, would be just the second nuclear plant to be built in the United Kingdom since the 1990s. Once a world leader, Britain’s nuclear industry atrophied after serious accidents in Ukraine and the United States spurred broad resistance to nuclear power.

Britain has legally committed to cutting carbon emissions. As a result, the government is reassessing its energy options amid a decline in natural gas from the North Sea oil fields and a decision to phase out the use of coal.

Proponents of wind and solar energy say Britain should be putting its money there, but those sources have not been able to match the steady supply of power nuclear energy produces. So nuclear plants are back in vogue. One is being built at Hinkley Point in southwest England, and at least four more are planned.

“It’s hard to conceive that nuclear does not have an important role to play,” said Steve Holliday, a former chief executive of National Grid, the British power system operator.

Britain’s renewed interest in nuclear power stands out among Western countries, where such plants have become forbiddingly costly and complex. The challenges were evident in October when Toshiba scrapped plans to build a plant in northern England.