The robot was also notably slow in climbing eight steps, cautiously lifting its legs one by one, and taking about a minute to go up each step.
With obstacles that aren't as even and predictable as steps, such as the debris at the Fukushima plant, the machine may need as much as 10 minutes to figure out how to clear an object, Toshiba acknowledged.
And, if it falls, it will not be able to get up on its own.
Still, Tokyo Electric Power Co. said it might use the robot to inspect the suppression chamber of the nuclear plant where a devastating meltdown occurred after a mammoth tsunami slammed into northeastern Japan on March 11, 2011.
Toshiba began developing the robot with hopes it would prove useful in helping to decommission the plant. No human has been able to enter the highly radiated chamber since the disaster.
"We need this to go in and first check what is there," Toshiba senior manager Goro Yanase said last week.
It was unclear when a decision on the robot's use would be made, said Tepco, which operates the nuclear plant.
Although Toshiba showed top-notch robotics, what the machine might be able to do appeared limited in the face of the disaster's magnitude and complexity.
Japan boasts among the world's most sophisticated robotics technology, exemplified in the walking, talking human-shaped Asimo robot from Honda Motor Co. The inability of such gadgetry to help out with the Fukushima disaster was widely criticized.
Part of the reason is that robots, although suited for tasks such as greeting visitors at dealerships, are too delicate. Their wireless remote-controlled networks are not designed to endure high radiation. Honda has acknowledged Asimo would not have been able to withstand the environment at Fukushima, as some had suggested.