Tokyo Electric Power has released still images from a video shot by a robot camera inside a reactor of the Fukushima No. 1 nuclear power plant, which showed contaminated water pooled at the bottom of the containment vessel.

The video was shot Wednesday by a robot put into the containment vessel of the reactor to investigate the situation there. The video was taken when the robot directed its camera toward a latticed floor of the containment vessel. The floor is made of metal.

The contaminated water was pooled about 70 centimeters below the floor, and the video showed the water surface quietly rippling.

TEPCO said the depth of the water is about 2.8 meters.

Yellow, blue-green and other colors could be seen on the floor.

“We have not been able to specify whether the colors were the effects of the robot’s lights or paint from equipment that melted and then adhered to the floor,” said a TEPCO official. TEPCO was to resume the robot’s video inspection Saturday.

Tadashi Narabayashi at Hokkaido University, an expert on nuclear reactor engineering, said: “The images indicated again that the melted fuel is in stable condition in the water. If an underwater camera is attached to the robot, it may be possible to shoot video of the melted fuel pooled at the bottom of the container.”