Japanese watchdog halts Hamaoka reactor safety screening over falsified seismic data

Japan’s nuclear watchdog said it is scrapping safety screening for two reactors at the Hamaoka nuclear power plant in central Japan after the plant operator was found to have fabricated data about earthquake risks.

The Nuclear Regulation Authority said it confirmed the falsification and that Chubu Electric Power Co. acknowledged the fabrication in mid-December. The regulator said it began an internal investigation in February after receiving a tip from a whistleblower that the utility had for years provided fabricated data that underestimated seismic risks.

NRA chair Shinsuke Yamanaka said ensuring safety is the first and foremost responsibility for nuclear plant operators. He added that seismic data was clearly fabricated and called it “outrageous” and “a serious challenge to safety regulation.”

The screening process, which included data that had been approved earlier, would have to start from scratch or possibly be rejected entirely, Yamanaka said. The NRA also said it is considering inspecting the utility headquarters, and that it will decide on the case next week without waiting for the utility’s probe results.

Chubu Electric had applied for safety screening to resume operations at the Hamaoka site’s No. 3 and No. 4 reactors in 2014 and 2015, respectively. The plant is about 200 kilometers (125 miles) west of Tokyo, and it is located on a coastal area where Nankai Trough megaquakes are considered a potential risk.

Two other reactors at the Hamaoka plant are being decommissioned, and a fifth reactor is idle. The NRA’s action is a setback to Japan’s attempts to accelerate nuclear reactor restarts, especially as the government has prioritized nuclear power amid rising energy costs and pressure to reduce carbon emissions.

The scandal surfaced Monday when Chubu Electric President Kingo Hayashi acknowledged that workers at the utility used inappropriate seismic data with an alleged intention to underestimate seismic risks. The company president apologized and pledged to establish an independent panel for investigation.

Public opinion in Japan remains divided due to lingering safety concerns after the 2011 Fukushima Daiichi meltdowns. Japan has 57 commercial reactors, and the NRA said 13 are currently operating, 20 are offline, and 24 are being decommissioned.