A handout picture taken and
released June 24, 2011 shows a T-Hawk survey vehicle (C) on the roof of
unit No. 2 reactor after it ditched at Fukushima Daiichi Nuclear Power
Station in Fukushima prefecture. The small unmanned vehicle, used to
help survey the damage and monitor the level of radiation at the plant,
crashed onto the roof of reactor after losing control, TEPCO said on
The other machine that failed was a drone helicopter that made an
emergency landing on a reactor roof at the Fukushima Dai-ichi nuclear
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
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.
TEPCO and the government have said they hope to achieve a cold
shutdown of the reactors by January by bringing the core temperatures to
below 100 Celsius (212 Fahrenheit.)
Workers have cooled the reactors and spent fuel by pumping in fresh
water, which becomes contaminated with radiation. About 110,000 tons of
tainted water have accumulated, and it could start overflowing in early
July unless workers get a trouble-plagued water treatment system working
The system became fully operational a week ago but shut down after a
few hours when one of the radiation absorbing cartridges reached its
limit much more quickly than expected. Matsumoto said the system, which
has since been on test run, has been working better after corrections
were made on some valves.
Goshi Hosono, director of the government’s nuclear crisis task force,
said the water treatment system, which eventually becomes part of a
cooling system, is key to resolving the crisis.