Japan’s ‘most dangerous’ nuclear plant manipulating earthquake data? Here's what the power company admits

Japan's power company has accepted that it is selectively presenting important safety data to clear regulatory inspections for restarting two of its nuclear reactors, which are currently offline. Chubu Electric Power Co. admitted it might have intentionally manipulated earthquake safety data for the Hamaoka Nuclear Power Plant in Shizuoka Prefecture, according to a report in the Independent

The company admitted that it is selecting specialised earthquake wave patterns, which are close to a calculated average, in order to make the projected maximum shaking (seismic motion) smaller than expected. It was reportedly intended to "smooth" and accelerate the stringent safety screening steps required to restart reactors at the site.

"We sincerely apologise for the incident. The actions could potentially shake the foundations of the nuclear power business," Chubu Electric president Kingo Hayashi said in a press conference.

The issue was alerted to the Nuclear Regulation Authority (NRA) by a whistleblower in February 2025. A senior official described the episode as “astonishing,” warning that it could erode confidence in Chubu Electric and cast doubt on the company’s suitability.

Why is Hamaoka Japan’s riskiest nuclear plant?

Japan’s Industry Ministry has directed Chubu Electric to submit a detailed report by April 6, 2026, explaining the lapse and outlining steps to prevent a recurrence. The utility has set up an independent panel of legal and technical specialists to probe the matter. After the revelation, Chubu Electric’s shares slid 8.2 per cent, marking their sharpest fall in almost a year.

Hamaoka is widely viewed by seismologists as Japan’s riskiest nuclear plant, as it lies directly above the Nankai Trough, a major seismic fault where a “megaquake” is expected. Government estimates put the probability of a major earthquake in the area at 87 per cent.

Professor Katsuhiko Ishibashi, a renowned seismologist, had warned back in 2003 that the Hamaoka nuclear power plant was Japan's most perilous due to earthquake risks. He predicted a potential disaster would ravage the Tokyo-Nagoya area, destroying over 200,000 buildings and triggering a massive tsunami. Post-Fukushima, reactors 4 and 5 were shut, and plans to restart reactor 3 were scrapped.

It was warned by Professor Katsuhiko Ishibashi, a renowned seismologist, in 2003 that the Hamaoka nuclear power plant was the most perilous in Japan due to earthquake risks. He predicted that a disaster would ravage the Tokyo-Nagoya area, which would destroy over 200,000 buildings and trigger a massive tsunami. Meanwhile, post-Fukushima, reactors 4 and 5 of the plant were shut, and plans to restart reactor 3 were discarded.