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KEPCO looking to decommission 2 reactors at Oi nuke plant

The No. 1 and No. 2 reactors (from right to left) at Kansai Electric Power Co. (KEPCO)'s Oi Nuclear Power Plant in Oi, Fukui Prefecture, are seen from a Mainichi Shimbun helicopter. (Mainichi)

OSAKA -- Kansai Electric Power Co. (KEPCO) is considering decommissioning two aging reactors at its Oi nuclear power plant in Fukui Prefecture, sources familiar with the case said.

In 2019, the operational life of these reactors -- the No. 1 and 2 reactors at the plant in the town of Oi -- will reach the 40-year limit set by the government following the outbreak of the Fukushima nuclear crisis in 2011.

Oi's No. 1 and 2 reactors are capable of generating a massive amount of power and are reportedly cost-effective. However, KEPCO has deemed that these reactors would not be profitable even if the company were to continue to operate the reactors beyond the 40-year limit as an exceptional measure, because it would cost a large amount of money to reinforce them to make them quake-resistant.

The output of the Oi plant's No. 1 and 2 reactors is approximately 1,175,000 kilowatts each.

Besides reactors at the disaster-hit Fukushima No. 1 complex, there are six reactors nationwide that their operators have decided to decommission in the wake of the disaster. The output of Oi's No. 1 and 2 reactors is larger than that of the six reactors.

Neither of the Oi reactors has been put back into operation since the March 2011 Great East Japan Earthquake, tsunami and ensuing nuclear crisis.

The government has set a 40-year cap in principle on the period of operating nuclear reactors following the disaster. However, the period can be extended by up to 20 years on condition that approval is granted by the Nuclear Regulation Authority.

However, a law providing for new safety standards designed to prevent a serious nuclear accident like the Fukushima disaster came into force in 2013, under which nuclear plant operators are required to take large-scale safety measures before reactivating reactors or operating them beyond the 40-year limit. Such measures would cost nuclear plant operators massive amounts of money.

Oi's No. 1 and 2 reactors were first put into operation in March 1979 and December 1979, respectively, and are to reach the 40-year limit in 2019.

It is technically difficult to reinforce these reactors because their containment vessels are small and their structures are complex.

Moreover, there is an active fault near the power station, and the estimated scale of tremors that could be caused by the fault has been gradually raised since the Great East Japan Earthquake. Therefore, it could cost KEPCO a massive amount of money to reinforce the reactors to make them resistant to such powerful temblors.

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