Chubu Electric Power says it may have presented data underestimating earthquake risks at its Hamaoka plant, shaking trust in Japan’s nuclear revival.
TOKYO: A Japanese nuclear plant operator has admitted it may have presented data underestimating earthquake risks to regulators.
Chubu Electric Power made the statement as Japan pushes to revive nuclear power nearly 15 years after the Fukushima disaster.
The company’s Hamaoka plant, located in a central Japan area at risk of a potential “megaquake”, is undergoing safety checks to restart two reactors.
Company president Kingo Hayashi said the estimated maximum seismic ground motion the plant could experience “may have been underestimated”.
“This incident could seriously affect the review process and undermine the trust of local communities,” Hayashi told an emergency press conference.
Japan shut down its nuclear reactors after the 2011 earthquake and tsunami triggered a meltdown at the Fukushima plant.
The resource-poor nation now aims to revive atomic energy to cut fossil fuel dependence and meet carbon neutrality goals by 2050.
The world’s largest nuclear plant, Kashiwazaki-Kariwa, is expected to restart operations later this month pending final regulatory approval.
The estimate of maximum seismic ground motion is critical for nuclear plant earthquake-resistant design.
Japan’s Nuclear Regulation Authority (NRA) approved Chubu Electric’s estimate of 1,200 gal, a unit measuring quake acceleration, in September 2023.
The NRA received a whistleblower tip in February 2025 that the utility “may have used data different from what was presented”, official Keiichi Watanabe said.
The watchdog has been conducting its own probe since receiving the information.
The NRA suspended its safety review for the Hamaoka plant in late December 2025.
The issue will be discussed in public meetings, with the first session scheduled for Wednesday.
The Hamaoka plant is located in Omaezaki, Shizuoka prefecture, near a major seismic fault line.
A massive Pacific earthquake is expected in the area, known as the Nankai Trough, in the coming years or decades.
The Japan Meteorological Agency issued its first special advisory for a possible “megaquake” in the trough in 2024, lifting it a week later.
The government estimates a quake in the 800-kilometre undersea trench could kill up to 298,000 people.
Such an event could also cause up to $2 trillion in damages from the subsequent tsunami.
Chubu Electric said it has set up a panel of lawyers to investigate the matter.
