Tepco said Thursday it has inserted an industrial endoscope into the primary containment vessel of reactor unit 2 at the Fukushima No. 1 plant, but images showed the level of coolant water was lower than the utility had estimated.
The endoscope took images of the vessel's interior around 4 meters from the bottom, but failed to detect any coolant water. Tepco had projected that the water level would have risen to about 4.5 meters in the vessel, based on the difference in pressure between its main body and a lower component, known as the suppression chamber.
Images taken by the endoscope showed the vessel was full of moisture, but the pipes and walls did not appear to be damaged, Tepco said.