Tokyo – Japan’s nuclear regulator announced on Wednesday that it would pause its review of Chubu Electric Power’s application to restart its Hamaoka nuclear power plant, citing concerns over falsified seismic data submitted by the utility. The Nuclear Regulation Authority (NRA) ordered Chubu Electric to submit a detailed report explaining the irregularities and said it would conduct on-site inspections to clarify the facts behind the misconduct.

The NRA’s move follows revelations that Chubu Electric tampered with data used in the safety assessments of the No. 3 and No. 4 reactors at the Hamaoka plant, located in Shizuoka prefecture on Japan’s Pacific Coast. The regulator had previously warned of a severe response, including the potential cancellation of the review process entirely, depending on the findings.

At its regular meeting on Wednesday, the NRA formalised the reporting order, giving Chubu Electric until March 31 to provide a comprehensive explanation of the cause of the falsification. In the meantime, the regulator said it would suspend the review process, citing the compromised credibility of the documents submitted so far.

Background and Timeline

Chubu Electric’s applications to review the two reactors at Hamaoka have been ongoing for over a decade. Experts had speculated that the restart of the units might have been possible around 2030. The utility’s latest business plan, however, projected a near-term restart, estimating that bringing the reactors back online could save approximately 260 billion yen annually in power procurement costs.

The Hamaoka site currently houses five reactors. Chubu Electric plans to decommission the No. 1 and No. 2 units and has not yet applied for a restart of the fifth reactor. The review pause comes at a time when Tokyo Electric Power is preparing to restart its first nuclear power plant since the 2011 tsunami disaster that destroyed the Fukushima Daiichi station. That event, the worst nuclear accident since Chernobyl in 1986, shook public confidence in nuclear energy and led to the shutdown of all 54 reactors in Japan.

Since then, Japan has restarted 14 of the 33 operable reactors. Restarting nuclear plants has been a priority for the government to strengthen energy security and reduce reliance on imported fossil fuels, which account for 60–70% of the country’s electricity generation. Prime Minister Sanae Takaichi has actively supported nuclear restarts as a key element of Japan’s energy policy, highlighting their importance for cost efficiency and reducing greenhouse gas emissions.

Impact and Implications

The falsification scandal at Hamaoka raises serious questions about corporate compliance and nuclear safety standards in Japan. The NRA’s decision to pause the review underscores the critical importance of credible data in regulatory assessments, particularly in a country that remains sensitive to nuclear risks after Fukushima.

If Chubu Electric fails to provide a satisfactory explanation by the March 31 deadline, the regulator could take even stricter measures, potentially halting restart plans indefinitely. Meanwhile, delays at Hamaoka could affect Japan’s broader energy planning, including efforts to reduce fossil fuel dependence and manage power procurement costs amid rising global energy prices.

Industry experts warn that any prolonged suspension could also impact investor confidence and public perception of nuclear energy. “After Fukushima, transparency and safety are paramount. Any breach of trust, especially in seismic data, is taken extremely seriously by regulators, the public, and the industry,” said a Tokyo-based energy analyst.

Looking Ahead

Japan faces a delicate balancing act as it seeks to resume nuclear power generation while maintaining stringent safety standards. The Hamaoka incident highlights the ongoing challenges for utilities and regulators alike, particularly in ensuring the accuracy of data critical for seismic and safety evaluations.

As the NRA conducts on-site inspections and awaits Chubu Electric’s report, the outcome will likely influence not only the Hamaoka plant’s future but also broader perceptions of nuclear energy governance in Japan. The government and regulators must demonstrate that compliance lapses will not be tolerated, reinforcing public trust while advancing energy security goals in an era of volatile fossil fuel markets.

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