The government on Wednesday expanded the scope of nuclear power plants it wants checked and ordered power generators to also inspect thermal power plants to see if there are any unchecked pipes susceptible to corrosion.
The order by the Nuclear and Industrial Safety Agency follows Monday's accident at Kansai Electric Power Co.'s Mihama Nuclear Power Plant, where superheated nonradioactive steam burst out of a ruptured pipe, killing four workers.
On Tuesday, the agency ordered the nation's electric utility companies to conduct inspections at facilities that use pressurized water reactors like those at the Mihama plant, whose ruptured section had never been inspected.
But Wednesday, the power companies were ordered to expand checks to nuclear facilities employing boiling water reactors as well as thermal power plants and submit reports by next Wednesday.
The agency, a unit of the Ministry of Economy, Trade and Industry, also ordered operators of power generation facilities for their own use to implement inspections by Aug. 20.
The scope of the order was expanded because pipe corrosion resulting from friction caused by the water and steam they carry could happen at other types of power plants, agency officials said.