Monju reactor faces long-term suspension over lax safety system

May 13, 2013

By HIDEKI MUROYA/ Staff Writer

Japan’s nuclear watchdog will indefinitely suspend the use of the Monju prototype fast-breeder reactor over the operator’s disregard for safety that continued even after the Fukushima nuclear crisis raised concerns across the nation.

The Nuclear Regulation Authority's order will deal a further blow to Japan’s nuclear fuel recycling program, which has long been plagued by technical problems and scandals.

In the latest case, the Japan Atomic Energy Agency, operator of Monju, was found to have skipped inspections of nearly 10,000 pieces of equipment since 2010, including crucial devices in the safety and emergency systems at the plant, based in Tsuruga, Fukui Prefecture.

The company also violated its own safety regulations, according to the NRA.

“Even when the reactor is offline, things stand in such a state,” an NRA official said after an on-site inspection of the reactor in February. “We cannot possibly approve a restart.”

The NRA will not allow the Japan Atomic Energy Agency to restart Monju operations until it comprehensively reviews its safety management system. The agency also plans to order the company to inspect all equipment items and overhaul its inspection programs.

The NRA’s order will dash the Japan Atomic Energy Agency’s plan to resume Monju operations by March 2014.

Hiroshi Hiroi, chief of the Monju facility, told The Asahi Shimbun that it will be difficult to complete inspections of all equipment items by the end of the year.

As of the end of March, 1,956 pieces of equipment remained uninspected, according to the Japan Atomic Energy Agency.

Hiroi also said the company will be unable to overhaul its inspection programs until at least next spring, indicating that the Monju reactor will not be restarted by the end of fiscal 2013.

The Monju, which can produce more nuclear fuel than it consumes, is a core component of Japan’s nuclear fuel recycling program along with a spent fuel reprocessing plant in Rokkasho, Aomori Prefecture.

The program involves extracting plutonium from spent nuclear fuel and recycling it as fuel. Japan has spent nearly 1 trillion yen ($10 billion) on the Monju program, but problems continue to pile up.

The Monju reactor started a trial run in 1995, but it was soon halted due to sodium leakage. It resumed operations in May 2010, only to be taken offline three months later after a fuel exchanger fell into the reactor.

In September 1997, the government imposed a one-year suspension on Monju’s operations over a falsified report on the sodium leakage.

The NRA’s order will be different from the 1997 suspension order.

The latest order means that the Japan Atomic Energy Agency cannot even make preparations for a restart, such as checking the exchange of fuel, functions of control rods and airtightness of the containment vessel.

The NRA’s predecessor, the Nuclear and Industrial Safety Agency, uncovered the lax procedures during a surprise inspection at the Monju reactor in September. NISA found that the Japan Atomic Energy Agency had not inspected key components of a sodium leakage detector.

The company’s internal investigation later found that 9,847 pieces of equipment remained uninspected since 2010, including 55 devices requiring top-level safety, such as a neutron detector and an emergency diesel power generator.

The NRA conducted an on-site inspection at the Monju reactor in February and questioned company officials.

According to the NRA, the Japan Atomic Energy Agency officials in charge of inspections said they believed that the equipment was safe and did not submit reports to their supervisors. Managers also said they were not informed that the equipment had not been inspected.

Hiroi acknowledged that company officials had let their guard down.

“Front-line workers did not know when the reactor would restart, and the entire organization did not share an understanding on when inspections should be completed," Hiroi said.

The Japan Atomic Energy Agency drew up inspection programs for Monju equipment in 2009, when the company tried to resume operations after the sodium leakage and other scandals deepened public distrust in the government’s nuclear policy.

But this sense of diligence did not last long.

The company’s slipshod practices continued even after the nation’s nuclear facility operators were required to take extra precautions after the Fukushima nuclear disaster in March 2011.

The NRA’s suspension order is only one of the problems surrounding the Japan Atomic Energy Agency.

Experts have pointed out that a geological fault that runs directly below the Monju reactor could move in tandem with a nearby active fault.

In addition, the NRA plans to require the company to protect the Monju against earthquakes, tsunami and other serious accidents in accordance with new safety standards that take effect in July.

By HIDEKI MUROYA/ Staff Writer
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  • Monju prototype fast-breeder reactor in Tsuruga, Fukui Prefecture (Asahi Shimbun file photo)

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