The operator of the Hamaoka nuclear plant, Chubu Electric Power, has admitted that it may have provided regulators with data that underestimated potential earthquake risks, in a significant development for Japan’s energy sector.

This revelation comes as Japan seeks to revive its nuclear power capacity nearly 15 years after the 2011 Fukushima disaster.

The Hamaoka plant, situated in central Japan within a region vulnerable to a potential "megaquake," is currently undergoing safety reviews in hopes of restarting two of its reactors.

During an emergency press conference late Monday, the company’s president acknowledged that the estimated maximum seismic ground motion used in their safety assessments may have been too low, an admission he warned could undermine the trust of local communities and shake the very foundation of their nuclear business.

The estimate of seismic ground motion, measured in "gal," is a critical factor in the earthquake-resistant design of nuclear facilities.

While the Nuclear Regulation Authority (NRA) had previously approved an estimate of 1,200 gal for Chubu Electric in September 2023, a whistleblower report in February 2025 suggested the utility may have used different data than what was officially presented.

This triggered an independent probe by the NRA, which has since suspended its safety review of the Hamaoka plant. Public meetings to discuss the discrepancy are scheduled to begin this Wednesday.

This controversy arises at a delicate time for Japan, which is attempting to pivot back to atomic energy to reduce reliance on fossil fuels and meet the power demands of artificial intelligence.

While the world’s largest nuclear plant, Kashiwazaki-Kariwa, is expected to restart later this month, the situation at Hamaoka remains tense due to its proximity to the Nankai Trough.

Experts warn that a massive earthquake in this 800-kilometer undersea trench could result in hundreds of thousands of casualties and trillions of dollars in damage. In response to the data concerns, Chubu Electric has established a panel of lawyers to investigate the matter further.