[The Verge] Fukushima: Another Robot Just Broke Down Investigating Record High Radiation Levels:
Another robot has died in the depths of one of Fukushima’s nuclear reactors, as attempts to locate and remove melted radioactive fuel continue.
This is the second robot in two weeks to meet its end in the Fukushima Daiichi nuclear power plant in Japan, the site of a major nuclear accident caused by the devastating 2011 earthquake and tsunami.
The robot’s mission was to investigate the pedestal underneath the Unit 2 nuclear reactor, where melted nuclear fuel is suspected to have fallen.
But about 10 feet away from its target, one of the robot’s tank-like treads got stuck, World Nuclear News reports.
Tokyo Electric Power Company (TEPCO), which operates the plant, decided to cut the robot’s cable and abandon it inside the reactor. A TEPCO spokeswoman told Phys.org that they don’t yet know whether radiation or debris stopped the robot.
Two feet long and shaped like a scorpion, this robot is equipped with a camera on its front, and another camera on its tail that can whip up and look around. It also sports temperature and radiation sensors.
Toshiba and the International Research Institute for Nuclear Decommissioning designed the scorpion robot to scoot on caterpillar treads like a tank through pipes about four inches wide.
It’s now at least the seventh robot to have broken down while investigating Fukushima’s nuclear reactors, which remain highly radioactive.
Reuters had counted up to five by March 2016. Last week, a scouting robot was sent in ahead to clear the way for the scorpion robot, but it was pulled back out after about two hours: the camera had been fried by record high levels of radiation estimated to be about 650 sieverts per hour. (For scale, a CT scan exposes you to 0.006 sieverts, and just half a sievert is enough to cause symptoms of radiation sickness.)
This is yet another setback for TEPCO, which still has not succeeded at removing the molten radioactive fuel from three of the four reactors that need to be decommissioned at Fukushima Daiichi. Still, TEPCO officials report that radiation levels measured outside the reactors are not dangerous, and the public is not at risk.
Source: The Verge