Robot, drone fail on Japan nuke-plant missions

The other machine that failed was a drone helicopter that made an emergency landing on a reactor roof at the Fukushima Dai-ichi nuclear power plant.

Operator Tokyo Electric Power Co is trying to cool down three molten reactor cores and stop radiation leaks to end a crisis set off when the March 11 earthquake and tsunami crippled the plant. The job is expected to take several more months, and is complicated by massive amounts of radioactive water that could soon leak into the sea.

The Quince robot, developed by Chiba Institute of Technology for nuclear and biological disaster relief activity, had ventured out into the Unit 2 reactor building to set up a gauge to measure the contaminated water pooling in the basement. Radioactivity inside the reactor buildings is too high for workers to take measurements there.

The machine got stuck at a staircase landing and failed to go downstairs, TEPCO spokesman Junichi Matsumoto said. A cable that was supposed to drop a gauge into the basement also malfunctioned.

The workers retrieved the robot and were going to make adjustments before sending it back in for another try, Matsumoto said. He did not elaborate.

The other machine that malfunctioned Friday was a T-Hawk drone helicopter, made in the US by Honeywell, that is used to inspect hard-to-access areas of the plant.

The drone developed engine trouble during a radiation sampling flight and made a remote-controlled emergency landing on the roof of Unit 2, the only one of the four damaged reactor buildings that still has a roof, Matsumoto said. Matsumoto said photos taken by a camera installed on a water pumping vehicle showed the drone was lying on its side, but neither the aircraft nor the roof suffered major damage.

The cause of the engine failure was under investigation. Matsumoto said it was not immediately known when or how the drone may be retrieved, but a backup drone can take over the mission.