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Running Monju reactor for 10 years would cost gov't 600 billion yen extra

The Monju fast-breeder reactor in Fukui Prefecture is seen in this photo taken from a Mainichi Shimbun helicopter. (Mainichi)

The government has calculated it will face about 600 billion yen in additional expenditure to keep the trouble-plagued Monju fast-breeder reactor operating in the Fukui Prefecture city of Tsuruga for another 10 years under current plans, it has been learned.

The government has already spent 1.2 trillion yen on the reactor, though the reactor has spent hardly any time in operation and remains idled. A team under Chief Cabinet Secretary Yoshihide Suga is now carefully considering what to do with the reactor, including the possibility of decommissioning it.

The Nuclear Regulation Authority (NRA) recommended to the Minister of Education, Culture, Sports, Science and Technology in November last year that jurisdiction of the reactor be switched from the Japan Atomic Energy Agency (JAEA) to another organization. It said that if this was not possible, then its operation should be drastically revised, or the reactor be decommissioned. The science ministry had been moving to separate the reactor's operational and management divisions from the agency and place them in the hands of a new corporation.

According to multiple government sources, after the NRA creates new standards for fast-breeder reactors based on lessons learned from the meltdowns at Tokyo Electric Power Co.'s Fukushima No. 1 Nuclear Power Plant, renovation work to meet these standards will become necessary in order to restart the Monju reactor. In operating the reactor, one quarter of its 198 fuel rods need to be replaced every four months, but the factory in Tokai, Ibaraki Prefecture, that produces Monju's fuel has not yet conformed to the new standards, and needs to be reinforced against earthquakes.

The Cabinet Secretariat has played a central role in considering the cost of operating the reactor. It is estimated that expenditure over a 10-year period, factoring in fuel production costs, power costs and personnel expenses, will reach about 600 billion yen. Even now, with the reactor idled, the annual cost of maintaining it stands at about 20 billion yen.

Some government officials are taking a stern view of the situation. One official voiced opposition to keeping the Monju reactor in service, saying that the amount being spent on it could be used to build a demonstration reactor (the next step after a prototype reactor), and that it is difficult to explain to the public the significance of spending so much.

The JAEA in 2012 calculated that it would cost about 300 billion yen to decommission the reactor, so either way, a large amount of public spending will be required.

Construction of the Monju reactor began in 1985, and it started generating electricity in August 1995, but around three months later it was closed due to a leak of sodium, which is used to cool the reactor. In May 2010 the reactor was reactivated, but 3 1/2 months later an accident with a fuel exchange component caused the reactor to be taken off-line. As a result it has operated and produced power for less than a year.

A science ministry official commented, "There are various preliminary calculations based on the envisaged methods of operation after the reactor is restarted, and we are scrutinizing those. We cannot comment on the cost."


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