Chubu Electric disclosed a report confirming it provided false explanations regarding seismic motion calculations for the Hamamoto nuclear plant. This revelation of fraudulent conduct during regulatory reviews significantly delays the path to reactor restart.
A special investigation committee established by Chubu Electric between January and September 2026 found that the company engaged in inappropriate behavior over a long period during compliance reviews for Units 3 and 4 at the Hamamoto nuclear plant since 2014. Specifically, the report identified instances where the company selected representative wave data that did not minimize residuals from average values in the "statistical Green function method," contrary to standard practice. The committee also noted cases where existing input values were reused after changing calculation conditions. Additionally, settings for connection periods in the "hybrid synthesis method" lacked appropriate justification and results were sometimes manipulated before presentation. The report stated these actions were incompatible with the objectivity and transparency required by the statistical Green function method, severely undermining the validity of the benchmark seismic motion.
The incident highlights a severe breakdown in the company's compliance system. Internal reports via help lines were submitted in 2019 and 2021 regarding seismic evaluation issues, but the responsible Nuclear Civil Engineering Department conducted its own investigations and submitted reports that concealed the reality. Similar concerns raised by "line-free experts" tasked with objectively checking review materials were also ignored. The report analyzed that a department-specific theory prioritizing early reactor restart had permeated the organization. It suggested that management pressure regarding schedule delays left field workers unable to cope with rigorous conditions, leading to misconduct.
Chubu Electric established its investigation committee on January 5, 2026, following the discovery of the issue, and received the final report on September 11. During meetings with the Nuclear Regulation Authority (NRA), the company faced intense questioning about detailed seismic evaluations and the rationale behind representative wave selection, including suspicions that backdated data was created to provide false explanations. The NRA has already halted compliance reviews for the Hamamoto nuclear plant. While Chubu Electric announced plans to reform its corporate culture and governance, deep-seated distrust among stakeholders in its nuclear operations remains, significantly diminishing expectations for a quick restart.
Analyst take
Restoring trust hinges on ensuring transparency. This case reflects fundamental flaws in organizational culture and governance rather than mere technical errors. Suggestions that management pressure for faster restarts fueled the misconduct indicate Chubu Electric must now verify the effectiveness of psychological safety and dissent mechanisms within its ranks. Investors should maintain a cautious stance, recognizing ongoing risks to its nuclear business until credible prevention measures are proven.
