Investigation into Chubu Electric Power's Data Fraud at Hamaoka Nuclear Plant

On January 26, 2026, Japan's Nuclear Regulation Authority (NRA) initiated an on-site inspection of Chubu Electric Power Co.'s headquarters in Nagoya, Aichi Prefecture. This investigation is focused on allegations of earthquake risk data fraud associated with the Hamaoka nuclear power plant located in Shizuoka Prefecture. The NRA's probe aims to uncover the circumstances and motives behind the misconduct, which has raised significant concerns regarding the safety assessments of the nuclear facility.

Chubu Electric HQ Inspection Starts over N-Plant Data FraudJapan’s nuclear watchdog starts probe of plant operator’s HQ over data fraud

Chubu Electric Power admitted to the fraudulent activities in December 2025, revealing that the company had been using inappropriate methods to select seismic wave data for reactor screenings since at least 2018. Specifically, the company chose seismic waves that did not represent average values, potentially leading to an underestimation of the seismic ground motions that the Hamaoka plant could face. The issue came to light following an external tip received by the NRA in February 2025.

Japan’s nuclear watchdog starts probe of plant operator’s HQ over data fraud

The NRA is expected to take several months to complete its inspection, during which it will review relevant documents and interview employees involved in the data manipulation. Following the investigation, the NRA will consider punitive measures against Chubu Electric, which may include disapproving the restart of the Hamaoka reactor and revoking the plant's installation permit. NRA chief Shinsuke Yamanaka emphasized the seriousness of the case, stating that it requires a thorough examination for potential severe punishment.

Japan’s nuclear watchdog starts probe of plant operator’s HQ over data fraud

At a regular meeting on January 14, 2026, the NRA discussed the implications of the data fraud and the necessary actions to ensure safety compliance. Yamanaka remarked on the gravity of the situation, indicating that the misconduct could lead to significant regulatory repercussions for Chubu Electric.

Japan’s nuclear watchdog starts probe of plant operator’s HQ over data fraud

The revelation of data fraud has sparked criticism from various stakeholders, including safety advocates and local residents. Concerns have been raised about the integrity of safety assessments for nuclear facilities, particularly in a country that has faced severe nuclear disasters in the past. Critics argue that such misconduct undermines public trust in nuclear safety regulations and calls for stricter oversight of nuclear operators.

Japan’s nuclear watchdog starts probe of plant operator’s HQ over data fraud

While the NRA's investigation is ongoing, there are discrepancies in the timeline of events leading to the admission of misconduct by Chubu Electric. The exact methods used to select the seismic data and the extent of the underestimation remain unclear, highlighting gaps in the available information that may affect the investigation's outcomes.

Japan’s nuclear watchdog starts probe of plant operator’s HQ over data fraud

As the NRA continues its inspection, the findings will play a crucial role in determining the future of the Hamaoka nuclear power plant and Chubu Electric's operational integrity. The outcome of this investigation could set a precedent for regulatory actions against similar misconduct in Japan's nuclear industry.

Japan’s nuclear watchdog starts probe of plant operator’s HQ over data fraud