The government formally decided at a meeting of Cabinet ministers concerned with nuclear energy on Dec. 21 to decommission the trouble-plagued Monju prototype fast-breeder nuclear reactor in Tsuruga, Fukui Prefecture.
Over 1 trillion yen in taxpayers' money has so far been invested in the reactor -- the core facility in the government's nuclear fuel cycle project in which spent nuclear fuel is reprocessed and reused in nuclear reactors.
Nevertheless, Monju, operated by the government-affiliated Japan Atomic Energy Agency (JAEA), will be shut down after being in operation for a total of only 250 days since the reactor reached criticality for the first time in 1994.
Still, the government, which is poised to continue the nuclear fuel cycle project, also agreed at the Dec. 21 meeting to draw up a road map by 2018 toward developing a fast reactor for the project.
In other words, the government is moving toward its "next dream" even without clarifying the cause of the failure of what they called "dream nuclear reactor" Monju and who is responsible for the fiasco.
"It's extremely important to maintain the nuclear fuel cycle project and promote the development of a fast reactor," Chief Cabinet Secretary Yoshihide Suga told a news conference following the decision.
However, continuation of the project will likely pose a challenge. The government's nuclear fuel cycle project involves two cycles -- one centered on a fast-breeder reactor and the other in which mixed-oxide (MOX) fuel, nuclear fuel made from reprocessed plutonium and uranium, is used in nuclear plants.
With the decision to decommission Monju, the cycle involving a fast-breeder reactor has failed. At the same time, the government has failed to smoothly press forward with the cycle involving the use of MOX fuel since most nuclear power plants have been idled since the outbreak of the Fukushima nuclear crisis in March 2011. The No. 3 reactor at Shikoku Electric Power Co.'s Ikata plant is the only nuclear reactor using MOX fuel, which is currently in operation.
A spent nuclear fuel reprocessing plant in Aomori Prefecture is undergoing safety screening by the Nuclear Regulation Authority (NRA), and pools holding spent nuclear fuel at atomic power stations across the country are filled to 70 percent of their capacities on average. Japan's stockpile of plutonium, which can be converted to use in nuclear weapons, has kept growing. By the end of 2015, the plutonium Japan possessed domestically and overseas had amounted to 47.9 metric tons.
The development of a fast reactor poses technological challenges. While a breeder reactor is designed to increase the amount of plutonium, the government emphasizes that a fast reactor that it is aiming to develop will play the role of an "incinerator" for nuclear waste such as by reducing the volume of high-level radioactive waste.
However, no experiment has been conducted on a fast reactor using actual radioactive waste. Hirofumi Nakamura, head of JAEA's planning and coordination division, acknowledged that the technology has not even reached the stage prior to putting it into practical use.
Serious questions persist about the feasibility of a fast reactor for economic reasons, and such a reactor is often dubbed as "modern alchemy."
The basic structure of a fast reactor and that of a breeder reactor are basically the same with the only differences being fuel types and arrangements. Therefore, a fast reactor, which is supposed to play the role of an incinerator for spent nuclear fuel, could be converted into a breeder reactor that produces plutonium.
A senior official of JAEA admits that "there is room for converting a fast reactor into one that breeds (plutonium)."
A fast reactor can be put into practical use after the development and production of experimental, prototype and then demonstration reactors. The government participates in the joint development of ASTRID, a French demonstration fast reactor. However, it remains unclear whether data and knowledge gained from the project in France, which is rarely hit by earthquakes, can be utilized in quake-prone Japan.
France is aiming to begin to operate the fast reactor in the 2030s, but the necessary funds for the project have only been allocated up to 2019. Questions remain as to whether Japan, which has aborted its project involving Monju, a prototype reactor, can be involved in a project to develop an upper-tier demonstration reactor.
Even those within the governing coalition are calling for caution in Japan's involvement in the joint development project in France. "Japan shouldn't ride on someone's (France's) back," said Hiroshi Hase, former education, culture, sports, science and technology minister.
NRA Chairman Shunichi Tanaka dismissed the feasibility of a demonstration reactor. "I understand that a demonstration reactor isn't realistic," Tanaka told a news conference on Dec. 21.