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At the meltdown of Fukushima Daiichi Nuclear Power Plant Unit 1, TEPCO started an internal investigation of the containment vessel using an underwater robot on the 8th. Initially, it was scheduled to start on the 12th of last month, but it was postponed for about a month due to equipment trouble. In the accident at TEPCO's Fukushima Daiichi Nuclear Power Plant in March 2011, it is believed that reactors Units 1, 2, and 3 melted down and "fuel debris" that had cooled and solidified accumulated at the bottom of each containment vessel. increase. Of these, for Unit 1, it is believed that there is a deposit with a thickness of about 1 meter on the fuel debris at the bottom of the containment vessel where water has accumulated, and the internal investigation is the most delayed because it is particularly difficult to investigate. increase. TEPCO began preparations for remote-controlled investigation of this Unit 1 using an underwater robot at 10 am on the 8th, and at 11:17 am, an isolation valve for a through hole for work leading to the inside of the reactor containment vessel. Open and throw in the underwater robot. Announced that it has started an internal investigation. At 3:27 pm, the underwater robot landed on the water collected at the bottom of the containment vessel. After that, the underwater robot moves underwater by the propulsive force of the rear screw called the thruster. There were no major problems until 5 pm, and the work is proceeding smoothly. At the site, in order to prevent the robot cable from getting entangled with structures in future investigations, we plan to continue the work of attaching a ring-shaped device called a "guide ring" to the inner wall of the containment vessel until midnight. Regarding the investigation inside Unit 1, TEPCO was planning to start work on the 12th of last month, but the data of the dosimeter built in the robot is not displayed accurately just before putting the underwater robot into the storage container. Or, of the 6 cameras that were installed, one of the monitors had troubles such as the time display stopping on the monitor screen, and the work was stopped. Regarding this, TEPCO held a press conference on the 7th and announced the cause of the trouble and countermeasures. It is said that the problem that the data of the dosimeter sent from the underwater robot was not displayed accurately was solved by changing the position of the wiring because there was noise in the dosimeter. In addition, it is said that problems such as the time display on the monitor screen stopping could be solved by replacing the cable because a problem was found in the cable. This investigation inside Unit 1, which was resumed on the 8th, is scheduled to continue until the 10th of this month, and TEPCO will hold a press conference on the 9th to explain the work results and progress.
Last updated: NTV NEWS