NRA Initiates On-Site Inspection Following Data Manipulation Allegations
Japan's Nuclear Regulation Authority (NRA) announced on Wednesday its decision to conduct an on-site inspection of Chubu Electric Power Co., prompted by allegations of data fraud related to earthquake risks at its Hamaoka nuclear power plant. The inspection will primarily target Chubu Electric's headquarters in Nagoya, with the Hamaoka plant in Shizuoka Prefecture also subject to investigation if deemed necessary.
This move comes after Chubu Electric admitted to manipulating seismic data submitted for the plant's safety screening, a process crucial for its potential restart. The NRA has also approved the scrapping of the ongoing screening for the Hamaoka plant's restart, with NRA chief Shinsuke Yamanaka stating that the process would 'go back to square one'.
Details of the Alleged Data Fraud
The core of the misconduct involves Chubu Electric intentionally selecting seismic data that potentially underestimated the earthquake ground motions the Hamaoka plant could experience. According to the company's own explanation to the NRA, they were supposed to adopt a method using the average value of multiple seismic waves calculated under different conditions. However, Chubu Electric reportedly used a different method in and before 2018 and intentionally designated a seismic wave different from the average value from around that year.
This 'cherry-picking' of data was brought to the NRA's attention by a whistleblower in February 2025. Following an internal investigation, Chubu Electric admitted its wrongdoing in December 2025 and publicly disclosed the issue on January 5, 2026. Chubu Electric President Kingo Hayashi acknowledged that quake data provided to the NRA was not calculated as it should have been and announced the establishment of an independent panel to investigate the incident.
Implications for the Hamaoka Plant and Broader Industry
The Hamaoka nuclear power plant, located in a region known for potential risks from Nankai Trough megaquakes, had its Units 3 and 4 under safety screening for a possible restart. All of Japan's 54 commercial reactors were shut down for safety checks following the 2011 Fukushima accident. The NRA's decision to scrap the screening means any future restart efforts for Hamaoka will require a complete re-evaluation.
NRA chief Shinsuke Yamanaka condemned Chubu Electric's actions as 'a fabrication of screening data directly related to (nuclear plant) safety and (therefore) clear misconduct'. In addition to the on-site inspection, the NRA will issue an order for Chubu Electric to submit a detailed report on the data fraud by the end of March under the nuclear reactor regulation law. The authority also plans to urge other power companies across Japan to ensure they prepare appropriate documents for reactor screenings, emphasizing the critical importance of accurate data for nuclear safety.
5 Comments
Noir Black
Safety first. No shortcuts when it comes to nuclear power.
Fuerza
This data fraud is unacceptable and must be punished severely. However, Japan still needs a viable energy strategy, and completely abandoning nuclear power without alternatives creates its own set of problems.
Manolo Noriega
Excellent! This is the strong oversight we need for nuclear safety.
Ongania
While the NRA's decision to scrap the restart screening is a necessary step for safety, it further delays Japan's energy independence goals. A more robust and transparent regulatory framework is clearly needed to avoid such issues in the future.
Fuerza
The whistleblower's role in exposing this is crucial, demonstrating the importance of internal checks. Yet, it's concerning that such a critical safety lapse went undetected for so long by official regulatory bodies.