Japan Halts Hamaoka Plant Reactors After Fabricated Safety Data

Japan’s Nuclear Regulation Authority (NRA) has suspended the relicensing process for two reactors at the Hamaoka Nuclear Power Plant following serious allegations of fabricated seismic hazard data by its operator, Chubu Electric Power Co.. This decision highlights ongoing concerns about nuclear safety in Japan, particularly as the country has been cautiously reactivating its nuclear facilities after the catastrophic Fukushima Daiichi disaster in 2011.

The NRA was informed of the data manipulation by a whistleblower in February 2022. However, the issue only became public this week when the NRA halted an evaluation process that could have paved the way for restarting the reactors at Hamaoka. The plant’s location on the coast near an active subduction fault amplifies the seriousness of the situation, echoing the circumstances surrounding the Fukushima incident.

In a detailed press release, Chubu Electric admitted to misrepresentations in its seismic safety evaluations. According to an English translation of the company’s statement, the evaluation of seismic risks involved artificially scaling up ground motion data from smaller earthquakes. Normally, the standard procedure requires creating a range of 20 different upscaled earthquake motion scenarios to determine the most representative average.

Chubu Electric now acknowledges that since 2018, its staff has been generating extensive collections of upscaled earthquake scenarios but was selectively choosing scenarios to present a more favorable risk assessment. The company did not clarify how this manipulation affected safety evaluations but suggested that the process was designed to minimize perceived risks.

Given Japan’s careful and gradual approach to nuclear plant reactivations, the decision to alter safety evaluations raises alarm bells. The Hamaoka plant, situated on Japan’s eastern coast, faces not only the risk of seismic activity but also potential tsunamis similar to those that led to the Fukushima meltdown. While the falsified data does not specifically address tsunami risks, one would expect heightened caution in safety assessments for such a vulnerable site.

In response to the fallout, Chubu Electric has appointed a committee of external lawyers to investigate the matter thoroughly. Additionally, the NRA has terminated the safety evaluation essential for any plans to restart the Hamaoka reactors. The timeline for resuming this process remains uncertain, leaving the future of the reactors in limbo.

This incident is particularly damaging for the NRA, which has faced criticism for regulatory failures that previously allowed significant safety risks to go unmonitored. Adding to the authority’s troubles, a recent report from Bloomberg indicated that a staff member lost a phone containing classified information while traveling through China, further complicating the agency’s credibility.

As Japan navigates its complex relationship with nuclear energy, the revelation of fabricated seismic hazard data presents a significant setback. The implications for public trust and regulatory oversight are profound, underscoring the necessity for transparent, accurate safety evaluations in such a critical sector.