Investigators raided a power utility company yesterday as police stepped up a criminal investigation into the company's role in Japan's worst-ever nuclear plant accident, which killed five people last month.
About 120 officials raided a branch of Kansai Electric Power, which is being investigated on suspicion of professional negligence resulting in death and injury in the Aug. 9 accident at its Mihama nuclear power plant, Tsuruga city police spokesman Shuichi Nosaka said.
Five people died when a corroded pipe ruptured, spraying plant workers with boiling water and steam. Six others were injured. No radiation leaked from the reactor.
Japan's public broadcaster NHK showed investigators with stacks of cardboard boxes walking into the utility company's Wakasa branch, about 320km west of Tokyo, to search for evidence. The branch oversees operations at the company's 11 nuclear reactors in Fukui prefecture.
Police had raided the utility company's offices at the Mihama plant and its affiliate, Nihon Arm Co, earlier this month.
Nobody has been arrested in the case.
On Monday, the Ministry of Economy, Trade and Industry ordered Kansai Electric to suspend Mihama's No. 3 reactor, which has been out of service since its accident, until it meets the government's safety standards.
In an interim report, the ministry's accident investigation committee said the utility -- as well as its affiliate in charge of safety inspections and a plant manufacturer, Mitsubishi Heavy Industries -- were responsible for the incident because they ignored safety controls.
An internal probe revealed that the wall of the pipe that burst had eroded to about one-tenth of its original thickness, to 1.5mm from 10mm.
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