CNIC Statement: Mission Impossible – Investigation Report on the Misconduct regarding Design Basis Seismic Ground Motions at the Hamaoka Nuclear Power Station –
September 16, 2026
On 14th September, Chubu Electric Power (Chubu Electric) published a report (hereinafter referred to as the Report) from the Special Investigation Committee concerning ‘inappropriate practices’ in the formulation of design basis seismic motions at the Hamaoka Nuclear Power Station.[i] When it was established on 5th January, it was called the ‘Third-Party Committee,’ but as it failed to comply with the Japanese Federation on Bar Associations’ (JFBA) ‘Guidelines for Third-Party Committees in Corporate and Other Scandals’[ii], it was later renamed the ‘Special Investigation Committee’. The Report cited three reasons for the loss of compliance of the committee as follows: “discussion with Chubu Electric regarding the committee’s structure and other issues from 26th December 2025 onwards,” “ensuring flexibility in Chubu Electric’s response, including the accurate verification of specialist or technical matters; confirmation of the content of internal investigations and verified facts, and the provision of timely explanations to stakeholders, by 5th January, the date on which this committee was established.” It then explains that “although the committee does not fully comply with the guidelines, it respects them… an agreement being reached with Chubu Electric.” On 5th January, Chubu Electric revealed the misconduct and, at the same time, announced that a third-party committee would investigate the matter.[iii] However, right from the moment of the announcement, it was not a third-party committee that would carry out the investigation. Chubu Electric had not only fabricated the design basis seismic ground motion, but also disguised the very nature of the investigation committee.
The JFBA guidelines clearly state in their preamble that “the purpose of a third-party committee is to restore trust and sustainability in companies and other organizations by conducting investigations and by disclosing the results of those investigations to all stakeholders.” So, what is the purpose of this committee which merely respect the guidelines? Based on what the report says, one cannot help but assume that its purpose is to downplay the issue and to keep the Hamaoka NPS operational at all costs. A typical example of this appears not in the report itself, but in the explanatory note posted above the download link for the report on their website. This note, which Chubu Electric claims to have received from the commission regarding the investigation report, states that “This commission does not recognize that the various practices in this case were appropriate or unproblematic. On the other hand, we do not consider it appropriate to simplify and summarily describe the practices using terms such as “falsification,” “fabrication,” “underestimation (of seismic motion)” or “data manipulation.” However, in fact, this report is parade of falsifications and fabrications. And yet, it declares that this case does not constitute misconduct when viewed as a whole.
In this incident, the misconduct was significant. It can be categorized as follows: Misconduct during the creation stage (1. The artificial selection of representative waves after generating a large number of candidate waves, 2. The artificial selection of representative waves not based on minimizing residuals, 3. The arbitrary selection of representative waves without considering the minimization of residuals, 4. The creation of representative waves by reusing input values, 5&6. Manipulation of the connection frequency, 7. Artificial selection of simulated seismic motions, and 8. Direct rewriting of waveform values), as well as fabrication of evidence during the review stage, and further attempts to cover up the matter after it came out to light. This report reveals how, as falsification during the drafting stage 1. became the norm, measures to save time (4.) were introduced, and this subsequently escalated into various forms of misconduct in order to keep the design basis seismic motions within a specific range. This raises the question of exactly when this irregularity (1.) started. However, the committee makes no attempt to clarify this point, merely stating that “regarding some of the cases where the selection method 1. was applied, its implementation was confirmed from the contractor’s FY2012 commission report and analysis report” and “it is recognized that the selection method 1. had already been applied in some cases at least by the time the application for license to modify the installation of Unit 4 of the Hamaoka NPS was submitted on 14th February 2014.” Meanwhile, Kyodo News reported on 9th July, citing sources close to the matter, that “the misconduct may have begun following the 2009 earthquake centered in Suruga Bay, in which Unit 5 recorded tremor that exceeded the design assumption, to avoid implementing additional seismic safety measures.”[iv] Yet the committee did not even attempt to identify the root cause or motive of the misconduct, which had been under investigation and had even been reported in the media more than two months previously. Furthermore, an agreement has been reached with Chubu Electric not to treat other instances of wrongdoing uncovered during the investigation as targets of the investigation. Assuming the committee’s aim was to minimize the scope of the issue, then this could be described as the correct approach.
On another note, the investigation report cited a number of factors in determining the causes, including “the unique justification theory” shared among some executives and staff of the Chubu Electric, a lack of control associated with the highly specialized nature of the nuclear division, and a lack of understanding among the management. The phrase “unique justification theory” is a catchy term, but on reading, it turns out to be a rather “ordinary,” arguing that the Nuclear Regulation Authority’s (NRA’s) regulatory measures are excessive, which is a common claim in the nuclear industry in recent years. Also, a point raised in the Report stating that the nuclear sector tends to turn into a “black box” is hardly a new observation; it has been pointed out repeatedly in the past. In fact, it would be fair to say that the whole nuclear industry suffers from the same deep-rooted problems.
Meanwhile, while stating that “this committee does not intend to assess the validity of the NRA’s finding and actions,” the committee has made comments with a certain reservation, stating that “even if the NRA’s findings were technically or academically unreasonable, or the committee’s responses were rigid,” misconduct cannot be recognized. Furthermore, the report sets out arguments that voices grievances and dissatisfaction with the NRA on behalf of Chubu Electric, including remarks such as “requirements imposed under the leadership of the NRA, which is in a position to act on the side of safety, carry the potential to be excessively stringent in terms of safety by their very nature,” and “There could also be a view that a balance should be achieved somewhere in relation to social necessity and utility.” In addition, the Report repeatedly argues for the necessity of nuclear power, using footnotes and other forms of citation.
At a press conference held on 14th September, Chubu Electric announced its intention to withdraw its application for the restart of the reactor and to resubmit it once preparations are completed. In addition, it focused especially on the A-17 fault, presenting it as if it were a problem that could be resolved. However, the Report indicates, for example, that “regarding the western fault zone of Omaezaki Spur, the connection period was set to 4 seconds based on the overlay of Stochastic Green’s Function Method (SGF) and Fourier spectra of wavenumber integration. However, for the A-17 fault, the eastern fault zone of Omaezaki Spur, and the Makinohara-Nanryo fault, using the above method resulted in wavenumber integration values that were too large to fall within the bounds of Ss-D (Design response spectrum-based ground motion). Therefore, the connection periods were set to 5 to 4 seconds, respectively, to ensure they fit within these bounds.” In addition, although it is not included in the Report, a report submitted by Chubu Electric to NRA in March states that “method 2. was initially developed as a measure for the A-17 fault, but was subsequently also applied to the selection of representative waves in cases involving branching faults in interplate earthquakes as well as cases linked with inland crustal earthquakes”. [v]
According to the Report, “since operations were suspended in May 2011, the cumulative cost required to maintain the Hamaoka NPS have totaled approximately 1.5 trillion yen, while the cumulative investment in safety improvement works has totaled approximately 280 billion yen.” As Chubu Electric sold 1.7 trillion kWh between FY2011 and FY2025, assuming the costs of the Hamaoka NPS were allocated evenly, this would mean an additional cost of 0.86yen per kWh. For a standard household (260kWh per month), this amounts to 2,676 yen per year, totaling approximately 40,000 yen over 15 years. Furthermore, there will be maintenance costs covering the period until restart, as well as substantial refurbishment costs. The Report states that the additional costs resulting from suspension (e.g., increased fossil fuel consumption) amount to 240 billion yen. this is considered to be the combined total for Units 3 to 5. However, the application for the restart of Units 3 and 4 have now been withdrawn, and no application has yet been submitted for Unit 5. It is highly likely that the cost-saving benefits of restarting the Hamaoka NPS will be offset by the cost required for the restart.
It is argued that nuclear power is indispensable for a stable electricity supply and decarbonation. At the same time, Hamaoka NPS has not generated even 1kWh of electricity for over 15 years, merely passing the costs on to consumers. It is no longer acceptable to allow this situation to continue indefinitely. The challenge confronting Chubu Electric is to evaluate the viability of the Hamaoka NPS from scratch.
If this were a third-party committee representing all stakeholders, the committee should have raised this point. However, the Special Investigation Committee’s mission was to resolve the problem. Yet, that mission is impossible to achieve, because even if the problem can be downplayed in words, the reality of the geological conditions at the Hamaoka NPS still exist. Chubu Electric should avoid reliance on deceit and quick fixes.
[i] Chubu Electric Power Co. (2026). Release of the Investigation Report Regarding Inappropriate Matters Concerning the Establishment of Reference Earthquake Motions in the Compliance Review for the New Regulatory Standards at Hamaoka Nuclear Power Station (Japanese) www.chuden.co.jp/publicity/press/1218316_3273.html
[ii] Japanese Federation on Bar Associations (2010). Japanese Federation on Bar Associations :Guidelines for Third-Party Committees in Corporate and Other Scandals (Japanese) www.nichibenren.or.jp/document/opinion/year/2010/100715_2.html
[iii] Chubu Electric Power Co. (2026).Regarding Inappropriate Matters Concerning the Establishment of Reference Earthquake Motions in the Compliance Review for the New Regulatory Standards at Hamaoka Nuclear Power Station www.chuden.co.jp/english/corporate/releases/pressreleases/1217661_5163.html
[iv] Kyodo News (2026). (Japanese) news.yahoo.co.jp/articles/cb3fce2c61cd3d04d6aaf84864fb847af073bf6e
[v] Chubu Electric Power Co. (2026). Report in Response to Requests for Information from the Minister of Economy, Trade and Industry and the Nuclear Regulation Authority Regarding Inappropriate Practices in the Formulation of Design Basis Earthquake Motion for the Compliance Review of the Hamaoka Nuclear Power Station Under the New Regulatory Standards www.chuden.co.jp/english/corporate/releases/pressreleases/1217685_5163.html
