Hitachi Ltd. said Monday it has discovered that data were falsified in connection with equipment at two nuclear plants in Shizuoka and Shimane prefectures, but shrugged off any safety concerns.
The falsified data relate to the heat-treatment process used by another company responsible for the pipe welds on the moisture-separator heaters, Hitachi and its group company said. The heaters increase thermal efficiency by removing moisture from steam sent to turn the turbines and heating it.
Hitachi admitted that the equipment used at Chubu Electric Power Co.’s No. 5 reactor at the Hamaoka plant in Shizuoka Prefecture and at Chugoku Electric Power Co.’s No. 3 reactor under construction at the Shimane plant in Shimane Prefecture, were not operating as specified. But Hitachi claimed that “there is no problem with its material or safety.”
Hitachi is checking for any similar data falsification incidents at its 17 other nuclear reactors.
Hitachi outsourced the heat treatment work, which was intended to make the pipes more resistant to cracking, to Japan Industrial Testing Co.
Although Hitachi was reprimanded by the government over a similar incident involving a subcontractor in 1997, it does not appear that the company is facing harsher punishment.
Instead, the Nuclear and Industrial Safety Agency told Hitachi and Hitachi-GE Nuclear Energy Ltd., to investigate whether other incidents of falsification had occurred and to submit plans to prevent a recurrence. Hitachi-GE Nuclear was formed by the merger of the nuclear businesses of the Hitachi and U.S. giant General Electric Co.
During the work, the pipes’ temperatures fell faster than specified because of inappropriate temperature management, but that data was erased from the records using a bleaching agent, according to Hitachi, its group company and other sources.
The incident at the Shimane reactor occurred last December when a person in charge of the work wrongly operated the heat treatment equipment and failed to spot the irregularity quickly enough, they said.
The person in charge was quoted as saying: “If (the mistake had been) found, I would have had to do the heat treatment process again at the yearend when I was supposed to be off. I didn’t want to do that.”
An official at Japan Industrial Testing apologized and vowed that the company will train its employees appropriately. Hitachi has also apologized and said it will work to prevent a recurrence.
Hitachi started to investigate after Chugoku Electric Power in March found possible data falsification related to the heat treatment work of the Shimane plant’s No. 3 reactor.
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