8 other pipe rupture accidents occurred in Japan nuclear plants

Kyodo News International, Tokyo --Aug. 19--TOKYO

Aug. 19--TOKYO -- Eight cases of accidents similar to a recent pipe rupture accident at the Mihama Nuclear Power Plant, which killed four people and injured seven others, occurred in the past at four other reactors, the government's nuclear watchdog said Thursday.

The Nuclear and Industrial Safety Agency under the Economy, Trade and Industry Ministry reported the cases to a meeting of the accident investigation board for the Aug. 9 accident at Mihama plant in Fukui Prefecture operated by Kansai Electric Power Co.

Of the eight cases, four took place at the No. 1 reactor of the Tsuruga Nuclear Power Plant in Fukui Prefecture operated by Japan Atomic Power Co., two at the No. 2 reactor of the Hamaoka Nuclear Power Plant in Shizuoka Prefecture run by Chubu Electric Power Co., and one each at the No. 1 reactor of the Hamaoka plant and the No. 2 reactor at KEPCO's Takahama Nuclear Power Plant in Fukui Prefecture.

The agency also said there were seven cases of similar incidents caused by such pipe corrosion at thermal power plants.

Nobody was injured in those accidents.

At the meeting at the ministry's Advisory Committee on Energy and Natural Resources, the second of its kind since the accident, KEPCO reported on how the accident at its Mihama plant occurred.

Four workers were killed and seven others injured by superheated steam that burst from a ruptured coolant water pipe at the Mihama plant's No. 3 reactor.

The agency said the damaged pipe was found to have been corroded by coolant water to a thickness of only 0.6 millimeter, compared with its original thickness of 10 mm.

KEPCO, the country's second-largest utility, had not inspected the corroded pipe since the reactor went into operation in 1976.

The agency also said, according to its investigation, that KEPCO failed to carry out pipe inspections at 17 designated points at six of its nuclear power plants.

KEPCO said Wednesday it failed to carry out pipe inspections at 11 designated points at three of its nuclear reactors in Fukui Prefecture, adding that it would immediately shut down the Takahama plant's No. 3 reactor which was in service.

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

The agency, meanwhile, said it is still investigating Sunday's steam burst incident from a ruptured pipe at a coal-fired thermal power plant in the town of Shinichi, Fukushima Prefecture. No one was injured in the incident.

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