The $1.1 billion deal announced this week propels Hitachi into the "new and uncomfortable" role as the owner of an entire atomic-power enterprise instead of just a contract reactor builder, says a report in the Financial Times.
Domestically, in the wake of the March 2011 Fukushima nuclear disaster, Japan aims to phase out nuclear power by 2040.
Masaharu Hanyu, head of Hitachi's nuclear division, hinted that the Japanese conglomerate had little choice but to win business abroad.
"We aren't doing it this way because we like it," he was quoted as saying by the Times. "We want a place to build nuclear reactors."
The deal comes amid uncertainty about the level of support nuclear developers can receive from the U.K. government, which has explicitly ruled out public subsidies for nuclear power.
Its forthcoming energy bill, slated to go before Parliament in November, is expected to guarantee returns for nuclear and renewable groups and reduce their investment risk.
That bill, said Energy Minister John Hayes, will "ensure energy security by providing investors like Hitachi with the certainty they need, and to get the best deal for the consumer," the BBC reports.
Other unknown factors regarding the deal, reports the BBC, include how much it would cost Hitachi to build the nuclear facilities in the United Kingdom, when the plants would be completed and who would operate them. Furthermore, the government-guaranteed "strike price," or minimum price for nuclear-generated power, hasn't been determined.
Hitachi said it will use its boiling water nuclear reactor technology, which is already licensed in other countries. But that system has yet to be granted U.K. safety approval, the BBC reports.
"Today starts our 100-year commitment to the U.K. and its vision to achieve a long-term, secure, low-carbon, and affordable energy supply," Hitachi President Hiroaki Nakanishi said in a statement.
"We look forward to sharing Hitachi's corporate vision and nuclear business policy with the management and employees of Horizon and working harmoniously with U.K. companies and stakeholders for the delivery of this vital part of Britain's national infrastructure and the creation of a strong U.K. nuclear power company."
Hitachi said it expects up to 5,000 direct jobs will be created at each site for the construction phase and another 1,000 permanent jobs per site when the reactors are operational.
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