I feel there was malicious intent
In the shadow of Fukushima's long memory, Japan's Nuclear Regulation Authority has found that Chubu Electric Power did not merely err in its safety calculations for the Hamaoka plant — it appears to have chosen deception, selecting favorable earthquake data from tens of thousands of points while telling regulators it had chosen randomly, then quietly rewriting records once scrutiny arrived. The scandal touches something older than any single company: the recurring human temptation to make danger look manageable on paper, even when the consequences of being wrong are borne by everyone. A 2023 reactor approval now rests on a foundation the NRA itself suspects was built from manipulated numbers, and the question of who knew — and when — is only beginning to be answered.
- Japan's nuclear watchdog has concluded that Chubu Electric deliberately misrepresented how it selected seismic data, filtering through as many as 30,000 data points to find figures that minimized earthquake risk rather than reflect it honestly.
- After regulators opened formal hearings in May 2024, the company retroactively altered 69 of 225 data sets under review — a pattern the NRA chairman called evidence of malicious intent, not administrative error.
- The fraud went undetected for years inside the regulatory process, surfacing only in February 2025 through an anonymous external tip, exposing how thoroughly the misconduct had been insulated from internal reporting.
- The NRA's 2023 approval of the Hamaoka reactors — granted on the basis of the now-suspect seismic assumptions — may face reconsideration, leaving the legal and safety status of operating reactors in a populated region unresolved.
- Regulators are now investigating whether company executives were directly involved across multiple departments, with an enforcement response, potentially including sanctions or approval reversal, expected by summer 2026.
Japan's Nuclear Regulation Authority has determined that Chubu Electric Power deliberately falsified the safety data underpinning its Hamaoka nuclear plant's earthquake risk assessments, and then moved to conceal the fraud once regulators began asking questions. The plant, located in Shizuoka Prefecture, houses two reactors whose approval now rests on figures the NRA believes were manipulated from the start.
The method was calculated in its simplicity. Chubu Electric told regulators it had randomly selected 20 seismic wave data points and used figures near the average for safety screening. In practice, the company directed a contractor to sift through more than 1,000 — and in some cases nearly 30,000 — data points, selecting only those that produced the most favorable outcome. By understating the maximum ground motion the plant might experience in an earthquake, the company could reduce the cost and complexity of earthquake-proofing measures and move construction forward more quickly.
The cover-up deepened after the NRA opened formal hearings in May 2024. Investigators found that Chubu Electric had retroactively rewritten 69 of 225 data sets under scrutiny — alterations made after regulatory attention had already arrived. NRA Chairman Shinsuke Yamanaka said publicly that the evidence suggests deliberate concealment, and the watchdog is now investigating whether executives were directly involved across multiple departments.
The misconduct had been hiding in plain sight for years. The NRA had broadly approved the company's seismic assumptions in 2023, unaware the underlying data had been cherry-picked. The fraud only came to light in February 2025, through an anonymous tip from outside the company. Chubu Electric disclosed the matter publicly in January 2026 and formed a third-party investigation committee — but by then the regulatory process had already been compromised.
The company issued an apology, calling the matter extremely serious, but offered no explanation for why records were altered after the inquiry began or why the misconduct had persisted internally without being reported. The NRA plans to announce its enforcement response by summer 2026, which could include sanctions, reconsideration of the 2023 reactor approval, or both — leaving unresolved whether the safety foundation for reactors serving a densely populated region was ever what regulators were told it was.
Japan's nuclear watchdog has concluded that Chubu Electric Power deliberately obscured evidence of safety data fraud at its Hamaoka plant in Shizuoka Prefecture, and the company appears to have destroyed or rewritten records after regulators began asking questions. The Nuclear Regulation Authority confirmed Wednesday that Chubu Electric used a method entirely different from what it had reported to obtain earthquake risk estimates for the facility's No. 3 and No. 4 reactors—a discrepancy that suggests the company knew its approach was improper and tried to hide it.
The core problem is straightforward: Chubu Electric told the NRA it had randomly selected 20 seismic wave data points and chosen figures close to the average for safety screening purposes. In reality, the company had asked a contractor to cherry-pick favorable data from more than 1,000 available points. In some cases, the selection process involved filtering through nearly 30,000 data points to find ones that supported the company's preferred outcome. By understating the maximum seismic ground motion the plant could experience during an earthquake, Chubu Electric could reduce the cost of earthquake-proofing measures and accelerate construction timelines.
The NRA's secretariat discovered that after the watchdog began formal hearings into the scandal in May 2024, Chubu Electric retroactively collected and rewrote data linked to the cherry-picking. Of 225 data sets under investigation, 69 were altered after the fact. NRA Chairman Shinsuke Yamanaka said at a news conference that the evidence points to deliberate concealment. "I feel there was malicious intent," he stated. The watchdog has instructed its secretariat to determine whether executives were directly involved in the cover-up, which appears to have spanned multiple departments within the company.
Chubu Electric applied for NRA safety screenings of the two reactors between 2014 and 2015. The process took years, but in 2023, the NRA broadly approved the company's assumptions about maximum seismic ground motion—the very figures now known to be based on manipulated data. The fraud remained hidden until February 2025, when the NRA received an external tip. The company made the misconduct public in January 2026 and established a third-party committee to investigate, but by then the damage to the regulatory process was already done.
In a statement, Chubu Electric said it took the matter "extremely seriously" and apologized "from the bottom of our hearts." The company did not explain why it had altered records after the NRA began its inquiry, or why the misconduct had persisted across multiple departments without being reported internally. The NRA plans to announce its enforcement response as early as summer 2026, after completing its investigation into executive involvement. That response could include sanctions against the company, reconsideration of the 2023 reactor approval, or both. The scandal raises a fundamental question about whether the safety basis for operating reactors in a densely populated region was compromised by deliberate data manipulation.
Citações Notáveis
We suspect there was a cover-up— NRA Chairman Shinsuke Yamanaka
We take it extremely seriously and apologize again from the bottom of our hearts— Chubu Electric Power Co. statement
A Conversa do Hearth Outra perspectiva sobre a história
Why would a power company deliberately underestimate earthquake risk at a nuclear plant? What's the incentive?
Money and time. A lower maximum seismic ground motion means cheaper earthquake-proofing. You don't have to build as robust. Construction moves faster. The company saves millions.
But they're running a nuclear plant. Doesn't that create enormous liability if something goes wrong?
Yes. But the fraud wasn't discovered for a decade. If you're a company under pressure to restart reactors and reduce costs, the incentive to cut corners can override the long-term risk.
How did they get away with it for so long?
The NRA trusted their methodology. Chubu Electric said they'd randomly selected data. The watchdog didn't independently verify the process. It wasn't until someone inside or close to the company tipped off the NRA in 2025 that anyone looked closely.
And then they rewrote the records?
Yes. After the NRA started asking questions in May 2024, they went back and altered 69 of 225 data sets. That's not a mistake. That's destruction of evidence.
What happens now?
The NRA is investigating whether executives knew. If they did, this becomes a criminal matter, not just a regulatory one. The 2023 approval that allowed the reactors to operate might be invalidated. The company faces serious consequences.