Fukushima Reactor Pressure Vessel Damage Under Review by Japanese Regulatory Commission

Fukushima Opposes Stance Saying "No Significant Impact"

Tokyo Electric Power Company (TEPCO), which has repeatedly stated that there is no problem with the internal damage of Unit 1 at the Fukushima Daiichi Nuclear Power Plant, also announced that the damage to the part supporting the pressure vessel inside the reactor containment vessel (the foundation) is expected to have "no significant impact."

The damage to the foundation supporting the pressure vessel of Unit 1 was confirmed in March through an underwater robot inspection. In response, the Nuclear Regulation Authority (NRA) of Japan instructed TEPCO to present countermeasures in case the pressure vessel were to fall. TEPCO maintains the opinion that the possibility of the foundation supporting the pressure vessel collapsing is low.

[Image source=Yonhap News]

According to a report by the Tokyo Shimbun on the 6th, the NRA expressed that the assumptions regarding the damage to Unit 1 were insufficient and hoped for a review. The NRA Secretariat, the Nuclear Regulation Agency, pointed out that TEPCO’s explanation that only cesium would be released as a radioactive material was incomplete, stating that "there is also a possibility that other radioactive materials could be released," and requested that scenarios involving higher exposure doses be examined. The newspaper also reported that the NRA requested raising the assumed magnitude of possible earthquakes and reviewing detailed response procedures.

At a review meeting held that day, TEPCO reported to the Nuclear Regulation Authority of Japan that even if the pressure vessel were to fall due to damage to the supporting part, causing radioactive materials to scatter outside the building, there would be no significant impact.

TEPCO predicted that even in the worst-case scenario where the pressure vessel falls and creates a hole in the containment vessel, the radiation exposure dose around the power plant would remain below the regulatory limits set for accidents. They also added that they plan to install equipment such as mobile filters by December.