The operator of the crippled Fukushima Daiichi nuclear power plant says it suspended a survey by a robot there after the device stopped working.
Tokyo Electric Power Company, or TEPCO, sent the scorpion-shaped robot into the containment vessel of the plant's No. 2 reactor on Thursday.
The survey was aimed at measuring radiation and temperatures there to gather data for scrapping the reactor.
TEPCO officials say the robot was advancing on a metal rail leading to a central area below the reactor's core while recording images and measuring radiation, but stopped moving before it could reach the center.