Tokyo Electric Power Co. (TEPCO) has failed to grasp the entire picture of melted fuel possibly accumulating inside the container vessel of the No. 2 reactor at the Fukushima No. 1 Nuclear Power Plant. The radiation levels inside the vessel are extremely high, to the extent a human could be killed in less than a minute, and even a robot designed to conduct a probe inside went down quickly.
In order for TEPCO to move ahead with decommissioning work on the No. 1 through No. 3 reactors at the plant, the utility needs to find out how much melted nuclear fuel lies inside the facilities, and where, in the aftermath of the meltdown of 1,496 fuel rods. The 26 workers were tasked with drilling a hole measuring 11.5 centimeters in diameter in the No. 2 reactor’s container vessel to open the way for the probe robot, using a remotely controlled machine.
Ryosuke Ishida, 28, an employee of a related company in Hokkaido, was in charge of removing the machinery that was used in the drilling work. In order to ward off the severely high radiation, he was wearing a lead jacket weighing 10 kilograms on top of his already tightly sealed protective gear. Each worker was allowed only five minutes for their task to keep their radiation exposure doses to no more than 3 millisieverts a day. The dosimeters they were carrying with them were set to beep when the radiation level reached 1.5 to 2 millisieverts, with an additional alarm set to go off when radiation doses hit every one-fifth of those levels.