YOKOHAMA – A new robot that raises its tail like a scorpion is scheduled to survey melted nuclear fuel inside one of the three wrecked reactors at Tepco’s Fukushima No. 1 plant.
Toshiba Corp., codeveloper of the device, which was demonstrated on Tuesday, said the robot will venture into reactor 2’s primary containment vessel in August after its operators undergo a month of training.
Officials hope the robot can see the fuel in the pressure vessel in the middle of the reactor. The location of the fuel has yet to be pinpointed because of the dangerously high radiation levels nearby.
The unprecedented work of decommissioning the Fukushima No. 1 plant, which was crippled in the 2011 earthquake and tsunami, is expected to take decades.
The scorpion robot is the second to enter a primary containment vessel, after a “snake” robot was sent into the worst-hit reactor 1 in April. The robot stalled inside the reactor and was unable to spot melted-fuel debris there.
This time, the scorpion crawler, which is 54 cm (21 inches) long when it is stretched out, will enter through a duct designed as a passageway for fuel rods.
During the demonstration at a Toshiba lab near Tokyo, the robot slid down a railing and stretched out like a bar, with a head-mounted LED showing its way. After crawling over a slight gap and landing on a metal platform, the robot lifted its tail and looked up the bottom of the control rod drive, a structure above the platform simulating where some melted nuclear fuel might be left.
The scorpion also demonstrated it can roll back upright if it hits an obstacle and rolls over. The ability comes from a tail joint in the middle that bends.
One operator controls the robot with a joystick, and another monitors the video feed from the robot and other data. At the Fukushima plant, the robot will be operated remotely from the command center in a separate building.
The work is expected to take a full day. The robot is designed to tolerate radiation, which should allow it to stay inside reactor 2 for more than 10 hours.