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Japan to Develop Domestic Fast Reactor with Support from US Nuclear Firm TerraPower

Yomiuri Shimbun file photo (for Web)
The Monju prototype reactor in Fukui Prefecture

A next-generation fast reactor in Japan will be developed in cooperation with a U.S. government-supported nuclear firm, according to sources.

As the development of fast reactors in Japan has been stagnating for many years, the agreement between the Japan Atomic Energy Agency and TerraPower, LLC will accelerate efforts to commercialize such a reactor by combining Japanese and U.S. technologies and expertise.

Fast reactors are nuclear reactors designed to utilize the characteristics of high-speed neutrons to burn plutonium and other fuels more efficiently than conventional reactors. To extract heat for generating electricity, liquid sodium is used as the coolant.

These reactors are key to Japan’s nuclear fuel cycle in which plutonium is extracted from spent nuclear fuel for reuse.

The new deal enhances cooperation and revises a memorandum signed by the JAEA, TerraPower and other entities in January 2022.

TerraPower is looking to construct a demonstration reactor in Wyoming, targeting around 2030 for the start of operations. Under the previous memorandum, the JAEA agreed to offer accumulated technologies to TerraPower.

From here on, the Japanese side will learn the latest nuclear reactor design technologies and expertise on safety measures from the U.S. side to use them for developing Japan’s demonstration reactor. A demonstration reactor is the final phase before the development of a commercial reactor, so TerraPower will be providing technological support to the JAEA and others in Japan.

The Economy, Trade and Industry Ministry released a road map in 2022 in which it set goals of starting the design of a demonstration reactor in the fiscal year ending March 2025 and operating it in the 2040s.

Reactor development has four phases: experimental, a basic phase without electricity-generating facilities; prototype, capable of generating electricity; demonstration, to verify economic viability; and commercial, for actual use.

Japan has developed the Joyo experimental fast reactor in Ibaraki Prefecture, which reached criticality for the first time in 1977, and the Monju prototype reactor in Fukui Prefecture, which reached criticality for the first time in 1994.

In 2016, however, the government decided to decommission Monju due to a series of troubles. Since then, development of a demonstration reactor has been at a standstill.