Japan and the United States have agreed to cooperate in the development of a next-generation fast reactor, despite having different aims and motivations regarding future projects.
Japan hopes the agreement signed Wednesday will provide a path for maintaining and improving its fast reactor technologies, while the United States wants to seize a leading position in the nuclear power market as a way to achieve its goal of reducing carbon emissions.
A senior official of the Education, Culture, Sports, Science and Technology Ministry said much was at stake in the joint development project between U.S. nuclear start-up company TerraPower, LLC, and Japanese entities including the Japan Atomic Energy Agency (JAEA).
“This is the last chance to prevent technologies Japan has accumulated over the years from being wasted,” the official said.
Development of a fast reactor has been a long-held ambition of Japan’s nuclear power policy. Such reactors will be essential for establishing a nuclear fuel cycle in which plutonium extracted from spent nuclear fuel is reused.
The decision to proceed with the cooperation after more than two years of negotiations with the U.S. side stemmed partly from a sense of urgency among Japanese officials that domestically developed technologies could eventually dry up.
For about 50 years, Japan has engaged in the development of the experimental Monju fast reactor in Fukui Prefecture, and the Joyo fast reactor in Ibaraki Prefecture. However, liquid sodium leaked at the Monju reactor in a 1995 accident, and the government decided to decommission the facility in 2016. Japan also participated in a fast reactor development project with France, but this was scaled back in 2018. Consequently, the nation lost opportunities to maintain and develop its technologies.
“Monju engineers and technicians are leaving and reaching their retirement ages one after another,” said University of Tokyo Prof. Naoto Kasahara, an expert in nuclear reactor structural engineering. “If they don’t become involved in the development of new reactors, they won’t be able to groom successors in the industry.”
As things stand, it is unclear when a new fast reactor will be constructed in Japan. “The joint development project with the United States is a precious chance,” Kasahara added.
Under this project, the JAEA will bring together domestic manufacturers and aim to get the floundering nuclear power industry back on its feet.
Japan currently possesses about 46 tons of plutonium retrieved from spent nuclear fuel. Plutonium is known around the world as a material that could be used in nuclear weapons, so highlighting Japan’s intention to use the plutonium for peaceful purposes by continuing developing fast reactors is crucial from the nation’s diplomatic strategy perspective.
At a House of Councillors plenary session on Jan. 21, Prime Minister Fumio Kishida expressed strong support for Japan-U.S. cooperation. Kishida plans to incorporate the promotion of nuclear power technology development in the green energy strategy that is currently being drawn up.
Efficient power generation
The United States is focusing on fast reactors as it looks to become a global leader in nuclear power and carbon emission reduction.
Construction of new nuclear facilities has lagged since the 1979 accident at the Three Mile Island nuclear power plant in Pennsylvania, but the administration of former U.S. President Donald Trump launched initiatives aimed at reviving the U.S. nuclear power industry and his successor President Joe Biden has taken over the reins.
To accelerate nuclear power’s revival, the United States is supporting the private sector and pushing ahead with the simultaneous development of several types of new reactors, including small modular reactors — miniaturized versions of conventional reactors that are cheaper and faster to build — and high-temperature gas-cooled reactors, in which meltdowns are less likely to occur and hydrogen also is produced while electricity is generated. Fast reactors are among those being developed.
High power-generation efficiency is a hallmark of fast reactors. Liquid sodium, which boils at about 880 C, is used as the coolant that circulates between the reactor and the heat exchange equipment. Energy from the reactor core is conveyed more efficiently to the generators than in conventional reactors, which are cooled with water. The reactors are structurally simple, and it is expected they will be economical enough to compete with renewable energy sources.
However, the United States’ attempts to develop such reactors have achieved little so far. Sodium, which reacts violently on contact with water and air, is highly flammable and is difficult to safely handle. This was part of the reasoning behind the U.S. decision to turn its attention to Japan, which possesses world-class testing facilities and has accumulated a wealth of experience — accidents included.
Yuki Kobayashi, a research fellow at the Sasakawa Peace Foundation, said, “From the perspective of preventing advanced technologies from being leaked, among other reasons, cooperating with Japan was a natural choice.”
As the confrontation between Washington and Beijing has intensified, it would have been difficult for the United States to join forces with France, which is cooperating with China in the development of next-generation reactors, he added.
The choice of fuel is the most conspicuous difference in the approaches of Japan and the United States.
The United States opts for highly enriched uranium fuel, used in its nuclear-powered warships, among other things. The long-lasting fuel reduces refueling frequency, which has an advantage in terms of cost.
Meanwhile, Japan anticipates using plutonium in any fast reactor it develops. For Japan, a key issue of this project will be how it can derive beneficial technologies.
However, uncertainties about the fast reactor construction plan remain a problem. The government has a strategy to start operating Monju’s replacement fast reactor in about the middle of the 21st century, but details are lacking.
Furthermore, the strategy lags behind those of other nations. India plans to begin commercial operation of a fast reactor in around 2025, Russia in around 2030 and China in the 2030s.
Energy industry expert Prof. Takeo Kikkawa of the International University of Japan said the government must move faster.
“Japan needs to possess its own fast reactor as quickly as possible to make the most of the technologies gained through cooperation with the United States,” said Kikkawa, who also serves as vice president of the university. “The government hasn’t even planned to build new conventional nuclear reactors or replace the existing ones. The government should swiftly and fundamentally overhaul a nuclear power policy that is falling far behind those of other countries.”