The company applied to the Nuclear Regulation Authority (NRA) for safety assessments of Hamaoka 3 and 4 in June 2015 and February 2014, respectively, to verify whether measures taken at the plant meet new safety standards. Both boiling water reactor units have since been undergoing reviews by the NRA.
However, on 5 January this year, Chubu announced “inappropriate matters relating to the formulation of the design basis ground motion in the review of conformity with new regulatory standards”. The company established an independent committee composed of external experts “to ensure transparency and fairness in investigating the facts and causes of the matter and considering measures to prevent recurrence”.
On Friday, the committee submitted its investigation report to Chubu, saying that some departments within the company are suspected of underestimating possible earthquake vibrations in data submitted to the NRA because they felt under pressure from senior management over delays in the schedule toward restarting. The data falsification began around 2012 at the latest, the committee concluded. Although whistleblowers raised concerns about data falsification in 2019 and 2021, their concerns were dismissed by senior management.
The company said on Monday: “Given the serious doubts that have arisen regarding the reliability of the application documents and the company’s subsequent handling of matters in the review process, it would not be appropriate to maintain the existing applications. Accordingly … the company resolved to withdraw the applications.”
Chubu said it plans to submit the withdrawal documents to the NRA “as soon as preparations are complete”.
“The company takes the findings of the investigation report with the utmost seriousness and sincerity,” Chubu said. “With a firm determination to ensure that a similar incident never occurs again, the company will undertake management reforms focusing on ‘transformation of mindsets and behaviours’, ‘transformation of organisational culture’, and ‘transformation and strengthening of governance and oversight functions’ in order to fundamentally rebuild both its governance framework and organisational culture. Through these efforts, the company will make every effort to thoroughly implement measures to prevent recurrence and restore the trust that has been lost.”
It announced the resignations, as of 30 September, of President and CEO Kingo Hayashi and Chairman Satoru Katsuno, who have taken responsibility for the manipulation of seismic data. Minoru Yasui, a director of the company, will succeed Hayashi as president from 1 October.
Prior to the March 2011 accident at the Fukushima Daiichi plant, Japan’s 54 reactors had provided around 30% of the country’s electricity. However, within 14 months of the accident, the country’s nuclear generation had been brought to a standstill pending regulatory change. Since then, 15 reactors have gradually resumed operation. According to Japan’s 7th Basic Energy Plan, adopted in February 2025, the country will “make maximum use of nuclear power”. Hamaoka units 3 and 4 are among 17 reactors at various stages of the restart review process.
