The announcement comes on the back of Kepco’s own internal investigations into the matter and it has reported the findings to the Japanese government.

In a statement Kepco said, “[We] failed to inspect supplementary steam pipes at four nuclear reactors. 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 & No. 4 reactors at the Oi plant.”

“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 [has] never inspected the pipe in the almost 28 years since the No. 3 reactor began service in 1976,” it added.

It is understood of the four reactors mentioned only the Takahama plant remains operational. The other three plants have been shut down for “inspections”. All four reactors are located in Fukui Prefecture.