March 31, 2023

TOKYO – Damage to the interior of a structure at the Fukushima No. 1 nuclear power plant can be seen in a photo released on Wednesday by Tokyo Electric Power Company Holdings, Inc.

The image shows the inside of the pedestal, a cylindrical reinforced concrete base supporting the reactor pressure vessel of the power plant’s No. 1 reactor. Part of the pedestal’s inner wall can be seen to have melted away, exposing its rebar.

The image was taken by a remotely controlled underwater robot on Tuesday. The concrete may have been damaged by the heat from the melted-down nuclear fuel during the March 11, 2011, nuclear disaster.

The pedestal has an interior diameter of about 5 meters, and the concrete is about 1.2 meters thick. During last year’s survey, it was confirmed that the outer wall near the pedestal’s inspection doorway was melted, but the interior of the pedestal was not visible. This time, an underwater robot camera was pointed at the interior from the entrance. On the floor of the interior, sedimentary debris, which is believed to include nuclear fuel debris, was also visible.

TEPCO is now taking pictures of the entire interior wall of the pedestal using the underwater robot to determine whether the concrete is damaged and lacks earthquake-resistance strength. The camera will also be turned upward to observe the bottom of the reactor pressure vessel.