Chubu Electric executives resign over Hamaoka seismic data manipulation

Executives at Chubu Electric Power, Japan’s third-largest utility, have resigned following an investigation that revealed years of seismic data manipulation at the Hamaoka nuclear power plant. President Kingo Hayashi and Chairperson Satoru Katsuno announced their resignations to take responsibility for the scandal, which has compromised the company’s credibility and forced the withdrawal of restart applications for reactors 3 and 4.

An independent commission found that technicians manipulated seismic stress data to ensure it met regulatory requirements, specifically attempting to stay below the 1,200 gal acceleration threshold set by the Nuclear Regulation Authority. The investigation revealed that staff discarded models showing high oscillations and instead used isolated favorable data points to create artificial statistical models. Although internal whistleblowers reported irregularities in 2019 and 2021, the reports were reportedly archived while management prioritized the commercial goal of restarting the reactors.

The Hamaoka site, located near Omaezaki, is situated near the Nankai Trough, a zone highly susceptible to a magnitude 8-9 earthquake. The scandal occurs as the Japanese government seeks to increase nuclear energy use to reduce emissions and energy costs. Chubu Electric must now undergo internal restructuring and restart the regulatory application process from the beginning.