Monju (in Tsuruga, Fukui Prefecture) was seen as a pillar of Japan’s nuclear fuel recycling program because it is designed to burn plutonium retrieved from huge stockpiles of spent fuel produced at nuclear power plants. Moreover, fast-breeder reactors are supposed to produce more plutonium than they burn while generating power. But Monju has operated on only 250 days over more than two decades because of many accidents, including a sodium coolant leak at the reactor in December 1995. The sodium coolant used in fast-breeder reactors is highly flammable and  very difficult to handle. So far, no country has developed a fast-breeder reactor for commercial purposes.

 On January 27, 2003 the Nagoya High Court's Kanazawa branch had handed down a historic ruling nullifying the government's 1983 permission for construction of Monju. The verdict recognized three main areas in which the Nuclear Safety Commission's (NSC) pre-construction safety review was inadequate. However, this court decision was later reversed. (5). Finally, in September 2016 it was reported that the government decided to cut its losses on the ¥1 trillion Monju fast-breeder reactor, pulling the plug on the project after years of mishaps, cover-ups and waste. [1]  Monju dates back to the 1980s, when work began amid the realization of a need to reduce reliance on fossil fuel. Almost all oil, coal and gas burned in Japan is imported.

Monju not only absorbed taxpayer money, but also suffered repeated accidents and mismanagement while only going live for a few months during its three-decade existence.

The Monju reactor reached criticality for the first time in 1994 but was forced to shut down in 1995 after the leak of sodium coolant and a fire. There was an attempt at a cover-up.

In November 2012, it emerged that the operator, Japan Atomic Energy Agency, had failed to check as many as 10,000 of Monju’s components, as safety rules require. The Nuclear Regulation Authority declared that the government-affiliated JAEA was “not qualified as an entity to safely operate” Monju.

It told the government either to find an alternative operator or scrap the project. The government was unable to find new management. Meanwhile, decommissioning Monju after 2016 will revive international concerns over Japan’s massive plutonium stockpile, extracted from spent fuel at the nation’s dozens of conventional nuclear power plants.

The stockpile is estimated at 48 tons of plutonium, enough to produce thousands of atomic bombs.

With no way to consume plutonium directly, the government plans to continue using MOX fuels — a mix of plutonium and uranium — in conventional nuclear reactors.

But most commercial reactors remain idle in the wake of the 2011 Fukushima nuclear disaster. The No. 3 reactor of the Ikata nuclear power plant in Ehime Prefecture is currently the sole active unit that uses MOX fuel.   Allegations of corruption are frequent.  "Massive amounts of tax money were funneled into the prefecture by the Liberal Democratic Party for all sorts of uses. Some were noble (construction of modern train stations, schools, hospitals and social welfare facilities). Some were corrupt (propaganda museums that played down the risks of nuclear power, all expense-paid “study”

tours to Europe’s nuclear reactor towns for local residents that included sightseeing trips to Paris). Nobody really knows how much money, directly and indirectly, went to Fukui and Tsuruga over the decades for “bearing the burden of Monju.” (6)

Tsuruga already hosted two conventional reactors and in 1983 preparations began for the construction of a new fast-breeder reactor called Monju.

Monju functioned for less than a year since its completion in 1994. The fast-breeder reactor — a cornerstone of Japan’s atomic energy strategy dating back to the 1950s — would use spent nuclear fuel from other atomic plants and is designed to produce more fuel that it consumes. The reactor, named after the Buddhist deity of wisdom, has barely operated since it first generated electricity in 1995, the year it suffered a sodium leak that led to a fire and subsequent attempted cover-up. Safety problems have continued to plague the facility ever since.

“The potential closure of Monju would be a major blow not just to the fast-breeder community in Japan, but also those supporting reprocessing of spent fuel,” M.V. Ramana, a professor at Princeton University’s Nuclear Futures Laboratory, said by email. [2]

Decommissioning will be big business, Monju means abandoning a project that has devoured more than 1 trillion yen ($9.82 billion) of government funds. According to other sources [3] the government has already spent 1.2 trillion yen (US$12bn) on Monju. The government calculated that it would cost another 600 billion yen (US$6bn) to restart Monju and keep it operating for another 10 years. Decommissioning has a hefty price-tag. According to a 2012 estimate by the Japan Atomic Energy Agency, decommissioning Monju will cost an estimated 300 billion yen (US$3bn).