TOKYO, Sept 7 (Reuters) - Japan's Chubu Electric Power said on Thursday it will buy a stake in U.S. NuScale Power from the Japan Bank for International Cooperation (JBIC) as it bets on small modular nuclear reactors to help combat climate change.

The move comes after Japan made a major nuclear power policy shift last year to tackle its energy crisis more than a decade after the 2011 Fukushima disaster prompted it to idle most of its reactors.

"As an equity owner, we want to expand our revenue base through investing in NuScale," Hiroki Sato, Chubu's global business division CEO, told reporters.

"The small modular reactor is an emission-free power source and it is important to secure all management options that are essential for the future decarbonised electricity sources," he said.

Chubu did not disclose the size of the stake or the price, but said the utility plans to take "not more than a majority of the JBIC's holdings," Sato said.

The JBIC and two Japanese companies - JGC Holdings Corp and IHI Corp - bought a total of 8.5% in NuScale in 2022, with the JBIC spending about $110 million.

The acquisition by Chubu is subject to approval by U.S. authorities, which is expected to take about one month, Sato said.

Small modular reactors are quicker to build and less costly than conventional units.

U.S. President Joe Biden's administration believes that maintaining existing nuclear plants and developing next-generation reactors is crucial for its goal of decarbonizing the economy by 2050.

So far the design for only one SMR, planned by NuScale Power, has been approved by U.S. regulators among next-generation reactors, though it still needs permits.

Asked about potential adoption of the SMR in Japan, Sato said: "It's difficult to deploy them in Japan anytime soon... but we have high expectations for the future development of next-generation reactors in Japan." (Reporting by Yuka Obayashi; Editing by Sharon Singleton)