TEPCO, the operator of the Fukushima nuclear plant, sent the remote-controlled device into the No. 2 reactor where radiation levels have recently hit record highs.
The “scorpion” robot, so-called because it can lift up its camera-mounted tail to achieve better viewing angles, is also designed to crawl over rubble inside the damaged facility.
But it could not reach its target destination beneath a pressure vessel through which nuclear fuel is believed to have melted because the robot had difficulty moving, a company spokeswoman said.
“It’s not immediately clear if that’s because of radiation or obstacles,” she said, adding that TEPCO is checking what data the robot was able to obtain, including images.