A coolant water pipe in another reactor at Kansai Electric Power Co.'s Mihama nuclear plant in Fukui Prefecture -- site of a fatal steam rupture earlier this month -- has also worn down to below the minimum thickness, government officials said Friday.

During inspections by the Nuclear and Industrial Safety Agency of the Economy, Trade and Industry Ministry on coolant water pipes of the No. 2 reactor, the thickness at one point of pipe was found to be 17.4 mm. The minimum requirement is 17.6 mm.

Kepco had reported Monday that coolant water pipes at the No. 2 reactor exceeded the required thickness at all points where they were inspected.

The nuclear safety agency has ordered Kepco to replace the pipe, agency officials said.

In the Aug. 13 accident at the adjacent No. 3 reactor, a corroded coolant pipe that had worn thin, and reportedly had not been inspected for 27 years, burst and spewed superheated steam, killing four workers and injuring seven, including one who died Wednesday.