(Photo : Molten substance accumulating on the bottom of reactor1 vessel. Photo was taken on the 9th of February, 2022.)
Molten substance was recorded in reactor1 by a drone camera for the first time after the nuclear accident in 2011.
Tepco has been operating the investigation inside reactor 1 since the 8th of February, 2022, which follows the previous investigation in reactor2 that took place five years ago. On the 10th of February, 2022, Tepco released the footage of a primary containment vessel (PCV) taken by a drone. Unidentified molten substance was seen accumulating in multiple locations on the bottom of PCV. PCV is filled with coolant water, however the drone detected the radiation level in the range of 1~2 Sv/h. Currently the composition of the substance has not been analyzed. Tepco comments it is assumably the mixture of molten reactor structure and the molten fuel dropped directly down from reactor pressure vessel (RPV). The volume and the distribution are not clear yet.
(Photo : Another molten substance (orange in the lower part of the image) captured accumulating on the wall of PCV. Photo was taken on the 8th of February, 2022.)