A major Japanese energy utility has admitted to potentially providing regulators with inaccurate seismic data, casting doubt on earthquake risk assessments for one of its nuclear facilities. Chubu Electric Power Company disclosed that its estimated maximum seismic ground motion calculations for the Hamaoka nuclear plant might have been significantly underestimated.
The revelation comes as Japan aggressively pursues nuclear power reactivation nearly fifteen years after the catastrophic Fukushima disaster. The Hamaoka facility, situated in central Japan’s Shizuoka prefecture, occupies a region scientists consider highly vulnerable to an impending ‘megaquake’ along the Nankai Trough seismic zone.
Company President Kingo Hayashi addressed journalists during an emergency press conference, stating: ‘This incident could profoundly impact our safety review process and damage the trust of local communities and stakeholders, potentially shaking the very foundation of our nuclear operations.’
The Nuclear Regulation Authority (NRA) suspended its safety evaluation process for Hamaoka in late December following whistleblower allegations received in February 2025. The informant claimed Chubu Electric might have utilized different data than what was officially presented to regulatory authorities.
NRA official Keiichi Watanabe confirmed the agency launched an independent investigation, with public hearings scheduled to commence Wednesday. The seismic ground motion estimate—previously approved at 1,200 gal (a measurement of quake acceleration intensity)—serves as the critical foundation for earthquake-resistant nuclear plant design.
This development occurs alongside Japan’s broader nuclear renaissance. The resource-limited nation seeks to reduce fossil fuel dependence, achieve carbon neutrality by 2050, and meet escalating energy demands driven by artificial intelligence infrastructure. The world’s largest nuclear facility, Kashiwazaki-Kariwa, anticipates operational restart later this month pending final regulatory approval.
Government projections indicate a potential Nankai Trough earthquake could trigger catastrophic consequences, including tsunamis claiming up to 298,000 lives and causing approximately $2 trillion in damages. Chubu Electric has established a legal panel to investigate the data discrepancies as regulatory scrutiny intensifies.