Chubu Electric Power Manipulated Seismic Data for Nuclear Plant Restart; President and Chairman Resign

External Investigation Finds "Management Reproach Acted as Pressure"

Chubu Withdraws Application for Hamaoka Units 3 and 4 Restart

Report on Decommissioning Costs for Units 1 and 2 Was Also Manipulated

Timeline for Hamaoka Plant Restart Remains Uncertain

It has been revealed through an external investigation that Chubu Electric Power manipulated seismic design data to facilitate the restart of its nuclear power plants. As the investigation found that criticism from the management led to the data manipulation, senior executives—including the president and chairman—have decided to take responsibility and resign.

According to Japanese media outlets including NHK on September 14, an investigative committee with external lawyers confirmed that data related to the seismic design of Units 3 and 4 at the Hamaoka Nuclear Power Plant, operated by Chubu Electric Power in Shizuoka Prefecture, had been manipulated. This was verified about eight months after suspicions were first raised in January.

The manipulated data pertained to the “reference seismic motion,” which forms the basis of the plant’s seismic design. Reference seismic motion represents the maximum level of earthquake shaking expected to occur at a nuclear power plant.

The investigation found that although concerns regarding data manipulation were raised multiple times within the company, no corrective action was taken. In particular, it was concluded that when management reproached the department responsible for delays in the Hamaoka plant’s restart schedule, this acted as pressure and led to the data manipulation.

Chubu Electric Power announced that, in response to the investigation’s findings, President Gingo Hayashi, Chairman Satoru Katsuno, and Advisor Akihisa Mizuno will resign effective September 30. In addition, the company has decided to withdraw its examination application to the Nuclear Regulation Authority that had been submitted for the restart of Units 3 and 4.

This is not the first incident involving the Hamaoka Nuclear Power Plant. Chubu Electric Power was previously found to have manipulated figures in a report submitted to claim costs for the decommissioning work of Units 1 and 2 at the same plant.

The repeated data manipulation and withdrawal of the restart application are expected to further cloud the prospects for restarting Units 3 and 4 at the Hamaoka plant. Given the anticipated rise in electricity demand—driven by the expansion of artificial intelligence (AI) data centers—there are concerns that these issues could hamper the Japanese government’s energy policy aimed at expanding the use of nuclear power.

Japan had previously established a plan to rebuild two to five aging nuclear plants by the 2040s to respond to increasing electricity demand.

This content was produced with the assistance of AI translation services.