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       Recently I posted a couple of articles about robots that are being developed to work in hostile environments such as nuclear reactors and nuclear waste facilities. Toshiba has just announced a new remote-controlled robot that it hopes can be used to investigate the three destroyed reactors at the Fukushima site of the 2011 nuclear disaster.
      One of the big problems at the Fukushima site is determining the current location of all the nuclear fuel that melted down through the floors of the containment vessels in the three destroyed reactors.
       Robotic probes have already been sent into the destroyed reactors to find the pieces of melted fuel. Some pieces of fuel have been located by probes which utilized a camera developed by Toshiba and the International Research Institute for Nuclear Decommissioning. Other pieces of fuel remain to be found.
       Toshiba says that they are planning experiments with the new robot this February. They are trying to determine exactly what technologies, equipment and processes will be needed to remove the pieces of melted fuel. This is thought to be the most difficult problem confronting the decommissioning process that is expected to require decades.
       The new Toshiba robot is a twelve-inch cylinder. It will carry a dosimeter for measuring radiation, a thermometer to monitor temperature, LED lights, a camera and a pair of tongs on the front end. The robot will slide down a pipe dangling on a cable attached to the rear end and travel to the bottom of the reactor vessel’s pedestal which is located below the core. The tongs can grasp pieces of melted fuel as wide as three inches and weighing up to four and a half pounds with its tongs.  
       Jun Suzuki is a ESS group manager at Toshiba. He said that “Until now we have only seen those deposits, and we need to know whether they will break off and can be picked up and taken out. Touching the deposits is important so we can make plans to sample the deposits, which is a next key step.”
        The robot has been designed to investigate the physical condition of the fuel debris. Other issues such as the radioactivity of the debris will require that samples be collected and safely stored. Additional equipment will be required to carry out these tasks.
         Tsutomu Takeuchi is an ESS senior manager on the Toshiba Fukushima decommissioning project. He said “We are taking one step at a time. First we'll find out if those deposits can be picked up.” He also said that if it turns out that the robot is unable to successfully grasp and lift pieces of debris, that will be an important finding.
       Some sort of cutting device may have to be added to the robot to enable it to cut off a piece of fuel debris that the robot can grasp and lift. Toshiba and the Japanese government hope to be able to determine proper methods for removing the melted fuel from each of the destroyed reactors at the Fukushima site during 2019. Actual removal of melted fuel will take place in 2021.