Japan's nuclear plant operator, Chubu Electric Power, has admitted that it may have underestimated the earthquake risks for its Hamaoka plant. The plant, located in an area at risk of a potential "megaquake," is undergoing regulatory safety checks with the aim of restarting two reactors. The company's president said the estimated maximum seismic ground motion that the plant could withstand during a quake "may have been underestimated." This revelation could seriously affect the safety review process and undermine trust in the company's nuclear business.
The Hamaoka plant is located in central Japan near a seismic fault line where a massive Pacific quake is expected to occur in the coming years or decade. Japan is moving to revive nuclear power nearly 15 years after the Fukushima disaster, with the goal of reducing its dependence on fossil fuels and achieving carbon neutrality by 2050. The world's biggest nuclear plant, Kashiwazaki-Kariwa, is expected to restart operations later this month, pending final approval from the Nuclear Regulation Authority (NRA).
The NRA has been conducting its own probe into the matter since receiving information from a whistleblower in February 2025 that Chubu Electric may have used different data from what was presented to the nuclear watchdog. The NRA suspended its safety review process for the Hamaoka plant in late December, and the issue will be discussed in public meetings.