Following Japan's deadliest nuclear plant accident last week, Kansai Electric Power Co. admitted Monday it failed to inspect supplementary steam pipes at four nuclear reactors.
Kepco, the country's second-largest utility, said the unchecked pipes -- used to feed steam to air conditioners and other devices -- are located at the No. 3 reactor of the accident-hit Mihama plant, the No. 1 reactor at the Takahama plant, and the No. 3 and No. 4 reactors at the Oi plant.
The revelation comes amid company investigations into last week's disaster.
All of the reactors are in Fukui Prefecture. The Takahama reactor is in service, while the other three have been shut down for inspections.
Kepco reported the findings to the government in the afternoon.
Four people were killed and seven others were injured in the Aug. 9 accident at Mihama, in which superheated steam escaped from a ruptured pipe. Kepco had never inspected the pipe in the almost 28 years since the No. 3 reactor began service in 1976.
Reporters covering the Mihama accident sent a letter of protest to Kepco President Yosaku Fuji on Monday, criticizing the company for its reluctance to reveal information regarding the accident.