Accident-hit Kansai Electric Power Co. said Wednesday it has not carried out pipe inspections at 11 designated points at three of its nuclear reactors in Fukui Prefecture, and added that it would immediately shut down the one reactor currently in service.

The pipes in question are at the No. 3 and No. 4 reactors at the Takahama Nuclear Power Plant and the No. 3 reactor at the Oi Nuclear Power Plant, according to Kepco.

Operations at the latter two reactors have already been suspended for regular checkups.

The revelation comes amid Kepco investigations following the country’s deadliest nuclear plant accident Aug. 9 at its Mihama Nuclear Power Plant, when steam from a ruptured pipe killed four people and injured seven others.

Kepco, the country’s second-largest utility, had not inspected the corroded pipe since the reactor went onstream in 1976. The damaged pipe was found to have been corroded by coolant water to a thickness of only 0.6 mm, compared with its original thickness of 10 mm.

Other power companies reported to the Nuclear and Industry Safety Agency on Wednesday that they have properly carried out inspections on all pipes at their thermal and nuclear plants.

The utility firms have been ordered to check documentation to ensure that inspections on pipes similar to the one that ruptured at Mihama had been carried out properly.

With the shutdown of the No. 3 reactor at the Takahama plant, seven of Kepco’s 11 nuclear reactors will be out of service. They include the No. 3 reactor involved in the accident at the Mihama plant.

Eight of the 11 inspection points that were overlooked involved pipes at the Takahama No. 3 reactor, including the main water pipes.

“As we inspected the same points at the Takahama No. 4 reactor, which is the same type, we concluded that the pipes were safe,” a Kepco official said.

The No. 3 reactor will nevertheless be shut down for inspection to dispel public concern, he said.

Kepco President Yosaku Fuji said that even with the immediate shutdown of the Takahama No. 3 reactor, the firm will be able to meet power supply demand from its customers.

Given the relatively low temperatures in the western Japan region, Kepco will be able to meet power demand if it receives some electricity supply from other utility firms, he said.

The latest revelations bring to 15 the total number of places that Kepco has failed to check, not including locations on the pipe involved in the Mihama accident.

Kepco said Monday it failed to inspect supplementary steam pipes at the Mihama No. 3 reactor, the No. 1 reactor at Takahama, and the No. 3 and No. 4 reactors at the Oi plant.

Kepco said Friday it will gradually suspend operations of all its nuclear reactors to check pipe safety.

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