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Next-Gen Small Nuclear Reactors Take Center Stage in Japan’s Power Policy Talks

Located underground for safety, these small reactors are cost competitive and “the closest thing to a stable energy source for the future,” said LDP Policy Research Council head Sanae Takaichi.



SMR power plant (rendering) for New Scale Power Co Ltd (photo by JGC Holdings)



Innovative next-generation small nuclear reactors that are highly safe and emit no CO2 have come into the spotlight. After all, the government has set a goal of reducing greenhouse gas emissions, including CO2, to net zero by 2050. 

Some candidates in the recent leadership election of the Liberal Democratic Party (LDP), including the winner Fumio Kishida, were outspoken on the usefulness of small modular reactors (SMRs) and small fusion reactors. It will be interesting to see whether Japan can play a leading role in this field in the future.

“Going forward, it will be important to secure technologies such as SMRs and small fusion reactors,” Kishida said during the LDP election.

Sanae Takaichi, who also ran for LDP president and assumed the position of LDP Policy Research Council chairperson under the new Kishida leadership, explained: “SMRs are the closest thing to a stable energy source for the future. They are located underground for security reasons.” 

She went on to say that she would “make the development of small fusion reactors a national project,” and suggested there would be revisions to the next Basic Energy Plan.

Prime Minister Fumio Kishida

A Future Path to Carbon Zero

Japan’s major power companies, while acknowledging development is still a long way off, are also positive about the future. A Kansai Electric Power Co. spokesperson remarked, “In addition to studying the design of next-generation light water reactors, we would like to proceed with technical studies on new reactor types, including SMRs and high-temperature gas-cooled reactors.” 

Among the various innovative and small-scale next-generation reactors, developments are the most active for the SMR, which could actually be put into operation in the latter half of the 2020s.

The SMR involves manufacturing an entire nuclear reactor as a single module and transporting it to a site for installation, enabling better quality control and shorter construction times. Unlike large-scale reactors that must be cooled by pumps in the event of an accident, SMRs have high safety features, such as the ability to remove heat by natural circulation of coolant. Without the need for pumps and other equipment, they require less initial investment and are expected to be more cost competitive than current reactors.

In the private sector, JGC Holdings Corporation (JGC HD) and IHI Corporation have invested in the United States-based NuScale Power, which is developing a pressurized water reactor (PWR) type of SMR. One feature of NuScale SMRs is that several modules would be installed in an underground pool, and in the event of an accident, the nuclear core could be cooled by natural cooling without the need for operators. 

NuScale’s reactor became the first SMR to receive design certification from the U.S. Nuclear Regulatory Commission in August 2020. According to JGC HD, the Utah Associated Municipal Power Systems (UAMPS) is currently preparing to apply for a construction permit, aiming to start operating an SMR power plant in Idaho in 2029.

In addition, Japan’s Hitachi-GE Nuclear Energy is currently developing a 300 MWe boiling water reactor (BWR) type of SMR, the “BWRX-300,” in collaboration with U.S.-based GE Hitachi Nuclear Energy. They are aiming to create a new market. Mitsubishi Heavy Industries is also working on the demonstration of a small PWR-type SMR.

LDP Policy Research Council head Sanae Takaichi

National Policy and Public-Private Support

The government has included ¥1.2 billion JPY ($10.5 million USD) for the development of innovative reactor technologies such as SMRs in its budget request for FY 2022, and plans to use the money to subsidize various projects in the private sector. The draft of the next Basic Energy Plan put forth by the government in July 2021 reads, “By 2030, utilizing the ingenuity and wisdom of the private sector, we will carry out the demonstration of small modular reactor technology based on international collaboration.”

However, according to Takanori Tanaka, a fellow at the Atomic Energy Society of Japan well-versed in SMR trends: “Japan has completely lagged behind in the development of SMRs, and regulations have not been able to respond. If we are serious about development, we must secure a site on the grounds of a national research institute for construction and verification of an SMR, as they have done in the United States and Canada.” 

He also points out the need for stronger government support. “Subsidies on the scale of ¥10 billion JPY ($87.5 million USD) would be needed to develop an actual SMR.” 

In response, a representative of the Agency for Natural Resources and Energy,  explained, “Our first priority is to gain the understanding of the public. [Once this is settled] and a plan to build a test reactor, not a research reactor, firms up, budgetary provision could become more generous.”


Meanwhile, small fusion reactors produce plasma in which nuclear fusion is initiated. Although stabilization of plasma is difficult, it is highly safe since the generation of plasma quickly stops due to external factors such as earthquakes, and no spent radioactive waste is generated.

At present in Japan, venture companies have entered the market through equipment supply and development contracts with nuclear fusion ventures in the U.S., the United Kingdom, and Canada that aim to generate fusion energy by around 2025. Expansion into this market is currently possible.

South Korea, which had once proclaimed a phase-out of nuclear power, is now said to be committed to developing an SMR, providing a global-scale tailwind for the development of innovative next-generation small reactors. 

Here in Japan, the direction of nuclear power policy may change with the new prime minister. Regardless, the potential for the timely development of next-generation small reactors will depend not solely on the private sector, but on how serious the government is in joining the effort.

RELATED: Energy Plans That Have No Strategy Will Lead to Japan’s Decline

(Read the Sankei Shimbun report in Japanese at this link.)

Author: Shinichi Nasu, Economics News Department