The Nuclear Regulation Authority has canceled safety reviews for Hamaoka Units 3 and 4 after Chubu Electric admitted falsifying seismic-risk data following a whistleblower tip. The regulator says the screening must be redone or could be rejected, and plans to decide next week. Chubu's president apologized and pledged an independent investigation while the NRA may also inspect the utility's headquarters. The case heightens public concern about nuclear safety amid efforts to restart reactors for energy and climate goals.
Japan Halts Safety Reviews At Hamaoka After Operator Admits Falsifying Seismic Data
This aerial photo shows Hamaoka nuclear power plant, owned by the Cubu Electric Power Co., in Omaezaki, central Japan, March 26, 2025. (Minoru Iwasaki/Kyodo News via AP)
TOKYO (AP) — Japan's Nuclear Regulation Authority (NRA) announced Wednesday that it has abandoned the safety reviews for two reactors at the Hamaoka nuclear power plant after the plant operator admitted to fabricating seismic-risk data.
The decision is a major setback for Tokyo's efforts to restart reactors to help control energy costs and meet carbon-reduction goals. Chubu Electric Power Co. had applied for screenings to restart Units 3 and 4 in 2014 and 2015; two other units at Hamaoka are being decommissioned and a fifth unit remains idle.
What Happened
The NRA said an internal investigation began in February after a whistleblower reported that Chubu Electric had for years provided falsified seismic data that understated potential earthquake risks. After confirming the falsification and following an admission from the utility in mid-December, the regulator suspended the screening process, NRA Chairman Shinsuke Yamanaka said.
Ensuring safety is the first and foremost responsibility for nuclear plant operators, Yamanaka said, adding that the seismic data had clearly been fabricated and that the conduct represents a serious challenge to safety regulation.
Chubu Electric President Kingo Hayashi acknowledged the misuse of inappropriate seismic data, apologized publicly, and pledged to establish an independent panel to investigate the incident. The NRA said it may also inspect the utility's headquarters as part of its review.
Next Steps
The screening for Units 3 and 4 — including material that had previously been approved — will have to be restarted from scratch or could be rejected entirely, Yamanaka said. The NRA expects to make a decision on the case next week and will not wait for the utility's internal probe to conclude before acting.
Context
The Hamaoka plant sits about 200 kilometers (125 miles) west of Tokyo in a coastal zone exposed to potential Nankai Trough megaquakes — a region regulators treat as particularly seismically hazardous. The scandal comes against the continuing backdrop of public concern after the 2011 Fukushima Daiichi meltdowns. Of Japan's 57 commercial reactors, 13 are operating, 20 are offline, and 24 are in the process of being dismantled or decommissioned, the NRA said.
This development is likely to complicate the government's plan to expand nuclear power as a response to higher energy costs and climate targets, and it raises fresh questions about oversight, whistleblower protections, and corporate accountability in Japan's nuclear sector.
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