TOKYO - Japan's nuclear watchdog said Thursday that security flaws in the handling of antiterrorism information have been found at Tokyo Electric Power Co. Holdings Inc.'s Fukushima Daiichi and Fukushima Daini nuclear power plants, following similar lapses at its Kashiwazaki-Kariwa plant in Niigata Prefecture.
The Nuclear Regulation Authority said multiple copies of such data, which are required to be kept under strict control in designated locations, had been stored in shared computer folders. The NRA said it will continue additional inspections to determine why the mishandling occurred.
The flaws came to light after TEPCO checked shared folders used by employees in charge of antiterrorism measures as well as staff computers. No external leakage of confidential information has been confirmed, the NRA said.
The watchdog said an employee previously found to have mishandled antiterrorism documents at the Kashiwazaki-Kariwa plant was not involved in the Fukushima cases.
The employee was found in an earlier investigation to have copied documents at TEPCO's headquarters and the Kashiwazaki-Kariwa plant since 2020, kept them in a workplace desk, photographed them with a smartphone and shared some of the contents with 16 others in the company.
TEPCO submitted a report to the NRA in April on measures to prevent a recurrence, including installing multiple locks on rooms where such documents are stored. The NRA is checking whether TEPCO has improved its handling of confidential information.
The four-reactor Fukushima Daini plant, which is set to be decommissioned, is located around 12 kilometers south of the six-reactor Fukushima Daiichi complex that was devastated by the massive earthquake and tsunami that hit northeastern Japan in March 2011.
