Japan’s nuclear watchdog halts plant’s reactor safety screening over falsified data

Japan’s nuclear regulator announced Wednesday it is terminating the safety screening process for two reactors at the Hamaoka nuclear power plant after the operator, Chubu Electric Power Co., was found to have fabricated earthquake risk data.

The decision represents a significant setback to Japan’s efforts to revitalize its nuclear energy sector, which has struggled to recover since the 2011 Fukushima Daiichi disaster. Currently, less than a quarter of Japan’s commercial reactors are operational, even as the government pushes to increase nuclear power generation to address rising energy costs and reduce carbon emissions.

Chubu Electric had applied in 2014 and 2015 to restart the No. 3 and 4 reactors at the Hamaoka plant, located approximately 200 kilometers west of Tokyo. The coastal facility sits in a region particularly vulnerable to megaquakes from the Nankai Trough, making accurate seismic risk assessment critically important.

The Nuclear Regulation Authority (NRA) began investigating the matter last February after receiving information from a whistleblower that the utility had been providing falsified data that downplayed potential seismic risks for years. The screening process was suspended after regulators confirmed the allegations, which Chubu Electric acknowledged in mid-December.

“Ensuring safety is the first and foremost responsibility for nuclear plant operators,” said Shinsuke Yamanaka, chair of the NRA. “It is outrageous and it’s a serious challenge to safety regulation.” Yamanaka noted that the seismic data manipulation was clearly deliberate, making the violation particularly serious.

The scandal became public on Monday when Chubu Electric President Kingo Hayashi admitted that company workers had used inappropriate seismic data with what appeared to be an intentional effort to minimize earthquake risks. Hayashi issued an apology and committed to establishing an independent panel to investigate the misconduct.

Yamanaka indicated that any future screening process would need to start from scratch, or might be rejected entirely. The NRA plans to make a final decision on the matter next week, proceeding independently of the utility’s own investigation.

The Hamaoka plant has been controversial since before the Fukushima disaster. Former Prime Minister Naoto Kan requested its shutdown in 2011 due to earthquake concerns. Two of its five reactors are already being decommissioned, while the fifth remains idle.

Japan’s nuclear industry faces complex challenges as it attempts to rebuild public trust. The country shut down all its nuclear plants following the Fukushima disaster, which was triggered by a massive earthquake and tsunami. The incident released radioactive materials into the environment and forced the evacuation of thousands of residents, many of whom have never returned to their homes.

Despite government efforts to promote nuclear energy as essential to meeting climate goals and energy security needs, public opinion remains deeply divided. Safety concerns persist, and communities near nuclear facilities often resist restart efforts.

According to the NRA, Japan currently has 57 commercial nuclear reactors, with only 13 in operation. Twenty reactors remain offline but potentially operable, while 24 others are in various stages of decommissioning.

The data falsification scandal at Hamaoka highlights the ongoing tensions between safety regulations and industry pressure to restart reactors. It also raises questions about oversight mechanisms and corporate governance within Japan’s nuclear sector.

The scandal could potentially impact Japan’s broader energy policy, which aims to increase nuclear power’s share in the country’s electricity mix to between 20-22% by 2030, up from less than 10% currently. This target was set as part of Japan’s strategy to achieve carbon neutrality by 2050.