Approximately 13,000 liters of water found in Unit 3 of Hamaoka Nuclear Power Plant; Chubu Electric continues investigation into data falsification

Japan's Chubu Electric Power announced on August 4 that water accumulation totaling approximately 13,000 liters was found in the turbine building and related areas of Unit 3 at the Hamaoka Nuclear Power Plant. The company stated that the accumulated water contains no radioactive substances and is currently investigating the specific cause.

According to Chubu Electric Power, at around 11:00 a.m. on the 4th, a worker from a partner company discovered approximately 5 liters of water in a passageway on the northwest side of the first basement floor of the turbine building adjacent to the reactor building of Unit 3. Subsequently, company personnel continued on-site inspections and confirmed at around 3:00 p.m. the same day that approximately 13,000 liters of water had accumulated in the connecting piping of the pump room, which is linked to the turbine building via water supply pipes.

Chubu Electric Power stated that although a drainage pump had been installed at the site, it failed to operate properly, preventing timely discharge of the accumulated water. The water involved is primarily used for cleaning, equipment maintenance, and firefighting, and contains no radioactive substances. The company preliminarily believes the water may have originated from leaks in the water supply piping or from rainwater inflow, and likewise contains no radioactive substances.

Separately, Chubu Electric Power disclosed that it has renamed the "Third-Party Committee," established in January this year to investigate the data falsification incident at the Hamaoka Nuclear Power Plant, to the "Investigation Committee." The reason for the renaming is that committee members had received explanations from the company regarding specialized technical matters of the nuclear power plant, and the company determined that this situation may not conform to the Japan Federation of Bar Associations' guidelines on the independence of third-party committees.

On January 5 this year, Chubu Electric Power announced that data submitted to Japan's Nuclear Regulation Authority (NRA) included intentional underestimation of the expected earthquake scale at the Hamaoka Nuclear Power Plant. On the same day, the company's board of directors decided to establish a third-party committee composed entirely of independent external experts, appointing three lawyers to participate in the investigation.

Chubu Electric Power stated that, as the investigation involves specialized nuclear power technology, the company deemed it necessary to provide explanations to committee members. Based on this situation, the company decided to adjust the committee's name to "Investigation Committee." The company also emphasized that committee members have no conflicts of interest with the company, their independence is guaranteed, the membership will remain unchanged, and the investigation will continue to proceed.

Previously, Chubu Electric Power had not specifically announced the renaming of the committee. In announcements issued after March, the company no longer used the term "Third-Party Committee," instead referring to it as a "committee composed entirely of external experts independent of the company (Investigation Committee)." On July 29, company President Shingo Hayashi mentioned at a press conference that a comprehensive judgment would be made after the Investigation Committee's findings are released.

Japan's Minister of Economy, Trade and Industry, Ryosei Akazawa, stated on July 4 that he understands the need for sharing specialized knowledge between Chubu Electric Power and the Investigation Committee members, but after the investigation results are released, he will strictly assess whether they are appropriate from both procedural and substantive perspectives.