Research & Development

Japan To Decommission Monju FBR, But Faces Opposition From Prefecture

By David Dalton
20 December 2016

Japan To Decommission Monju FBR, But Faces Opposition From Prefecture
The Monju fast breeder reactor in Fukui prefecture, Japan.

20 Dec (NucNet): Japan has decided to decommission the Monju prototype fast-breeder reactor, but is facing opposition from authorities in Fukui prefecture where the reactor is located.

The Japan Atomic Industrial Forum said Fukui governor Issei Nishikawa said he would not accept the decision and would demand that the government reconsider it.

According to Jaif, the government has said that a new experimental research reactor would be built in the prefecture and that Monju will be used for research.

Jaif said confirmation of the decision was expected at a Cabinet meeting today, 20 December 2016.

Monju reached criticality for the first time in 1994, but it has mostly been offline since 1995. In November 2015 Japan’s nuclear regulator, the NRA, said state-run Japan Atomic Energy Agency (JAEA) was not fit to operate Monju because it had repeatedly failed to correctly carry out inspections of the plant.

According to Jaif, the NRA recommended at the time that the government find another operator to replace JAEA within six months.

In December 1995, just months after Monju first started power transmission, it was shut down when 640 kg of liquid sodium leaked from a cooling system, causing a fire.

There were no injuries and no radioactivity escaped plant buildings, but the incident was compounded by JAEA’s attempts to cover up the scale of the damage.

Monju was allowed to restart in May 2010 after JAEA carried out a review of the plant’s design, and its safety procedures, which were shown to be inadequate.

However, operation was again suspended in August 2010 after a fuel handling machine was dropped into the reactor during a refuelling outage.

In May 2013 JAEA president Atsuyuki Suzuki resigned after the NRA prevented the restart of Monju due to inspection deficiencies.

In November 2012 it was revealed that JAEA had failed to conduct regular inspections on almost 10,000 out of a total 39,000 pieces of equipment at Monju.

Some of these included safety-critical equipment. Monju is a 246-MW sodium-cooled fast reactor at the Tsuruga nuclear power station in Fukui Prefecture, southwest Japan.

It is designed to use mixed fuel rods of uranium and plutonium, and to produce more fuel than it consumes.

Regarded as the core facility of the government’s policy for nuclear fuel recycling, Monju is different from conventional nuclear power plants, which use water as coolants. Monju uses sodium as the coolant, meaning more sophisticated technology is required for its operation.

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