Chubu Electric Power, the operator of the Hamaoka nuclear power plant in central Japan, said earlier this week that the plant's employees may have used selectively selected data on earthquake scenarios in seismic resistance tests, in order to overcome the regulatory appraisal process to restart this nuclear power plant.
Also this week, the Japan Atomic Energy Agency (NRA) announced that it had discovered violations by Chubu Electric Power during the appraisal process and decided to temporarily suspend the review of the dossier.
This incident is a strong blow to the Japanese government's efforts to restore confidence in nuclear power. Since the Fukushima nuclear disaster in 2011, concerns about the safety of nuclear power plants in Japan have always been very high.
Meanwhile, Japanese authorities are promoting the reactivation of nuclear reactors according to stricter safety standards, in order to reduce greenhouse gas emissions as well as ensure stable power supply.
The Hamaoka nuclear power plant has been suspended since May 2011, similar to other plants across Japan, after the Fukushima disaster.
This is unbelievable. This completely breaks the trust in the operating unit. The incident will make the public doubt the company's operating capacity" - a senior NRA leader said.
The Hamaoka nuclear power plant is located in an area predicted to have a super earthquake at the Nankai Trench off the Pacific Ocean, one of the areas with the highest seismic risk in Japan.
Chubu Electric has submitted an appraisal application to restart reactors No. 3 and 4 at the Hamaoka complex, Shizuoka Prefecture, in the period 2014-2015.
According to a report sent to regulators, Chubu Electric said it has chosen a type of earthquake wave that is closest to the average level among 20 different scenarios, to calculate standard seismic movement, i.e., the maximum vibration that reactors can withstand when an earthquake occurs.
However, the personnel in charge of implementing Chubu Electric's report may have deliberately chosen this option to ensure smooth appraisal.
Chubu Electric has established a council with the participation of lawyers to investigate the case.
We sincerely apologize for this incident. These actions could shake the foundation of the entire nuclear power industry" - Chubu Electric Chairman Kingo Hayashi said at a press conference in Nagoya.
According to the NRA, a complainant contacted the management agency in February 2025 to report the incident.
Previously, functional agencies basically approved the standard seismic movement of Chubu Electric in September 2023.
On January 5, the Japanese Ministry of Economy, Trade and Industry requested Chubu Electric to submit an explanatory report in accordance with the provisions of Japan's electricity business law.
In November 2025, Chubu Electric announced that it had detected 20 cases of violations in contracts and procedures related to safety at the Hamaoka nuclear power plant.
Hamaoka is currently the only nuclear power plant operated by Chubu Electric.
