Japan's nuclear safety regulator has suspended a crucial review to restart reactors at a major power station after the operator confessed to manipulating critical safety data.
Safety Review Suspended After Admission
The Nuclear Regulation Authority (NRA) halted its assessment of the Hamaoka nuclear power plant after operator Chubu Electric Power Company admitted to "cherry-picking" earthquake safety data. The company revealed on Monday that it had selected a specific seismic wave model to make the plant appear safer and accelerate the screening process for restarting two reactors.
Chubu Electric president Kingo Hayashi publicly apologised at a press conference, stating the actions "could potentially shake the foundations of the nuclear power business." The company has now established an independent expert panel to investigate the misconduct.
Whistleblower Reveals Deliberate Manipulation
The regulator first learned of the issue in February 2025 after being contacted by a whistleblower. The misconduct involved calculations for the plant's "standard seismic motion"—the maximum ground shaking the reactors are designed to withstand.
Chubu Electric told regulators it had chosen an earthquake wave model closest to the average of 20 possible patterns. However, the company conceded that employees may have deliberately selected this model to present a more favourable safety profile and speed up regulatory approval.
A senior agency official described the matter as "unbelievable," saying it shattered trust in the operator and would make the public question its eligibility to run nuclear facilities.
Major Setback for Japan's Nuclear Ambitions
This revelation represents a significant blow to Japan's efforts to return to nuclear power to enhance energy security and reduce greenhouse gas emissions. The Hamaoka plant, located in Shizuoka Prefecture, is now unlikely to restart in the foreseeable future.
The plant originally had five reactors. Reactors 1 and 2 were permanently shut down in 2009. The remaining three reactors were taken offline following the 2011 Fukushima disaster. In the wake of Fukushima, reactors 4 and 5 were ordered shut, and the planned restart of reactor 3 was cancelled.
Hamaoka was built to withstand only an 8.5-magnitude earthquake and an 8-metre tsunami, whereas the 2011 disaster involved a magnitude 9 quake and waves up to 15 metres high.
Chubu Electric had applied for a review to restart the Hamaoka reactors between 2014 and 2015. The NRA approved the standard seismic motion calculation in September 2023, a decision now under intense scrutiny.
The Japanese industry ministry has ordered Chubu Electric to submit a detailed report by 6 April 2026, explaining the cause of the misconduct and outlining preventative measures.
The financial markets reacted sharply to the news. Shares in Chubu Electric plunged 8.2%, marking their steepest fall since April 2025.
