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TEPCO begins studying dislodged reactor cover

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Translation by Rachel Clark
July 17, 2019
At TEPCO’s Fukushima Daiichi Nuclear Power Station Unit 1, the top lid of the containment vessel covering the reactor has been shifted (or out of proper position). Because of this, the radiation dose in the building became high, which has been an obstacle to decommissioning work, TEPCO has started to conduct its investigation on the 17th to check the situation of the shifted upper lid and contamination using a robot.
 
The first unit of Fukushima Daiichi Nuclear Power Plant was affected by the hydrogen explosion at the time of the accident, and the upper lid of the three layers of the containment vessel covering the nuclear reactor was shifted from its proper position.
Because of this, radiation dose around this reactor goes up as high as 2.23 Sv/h.
For this reason, it is necessary to lower the radiation dose either by taking out the fuel left in the spent fuel pool in the Unit 1 building, or by correcting the position of the lid that weighs about 60 tons, or by installing a new cover, etc. On the 17th, TEPCO started to investigate the situation by a remote-controlled robot for more details.
In their plan, first they want to put the robot in the gap between the upper and middle lids among the three layers of lids, then to lower the camera and confirm the condition of the lowest tier, and to wipe the surface of the lid measured with a three-dimensional scanner, in order to collect radioactive materials.
On the 17th, TEPCO started the investigation from 3:00 pm. What they actually doing now is to take photos in order to confirm the view of a robot’s camera.
The investigation will be continued through early next month, of which the results will help TEPCO examine the necessity of decontamination as well as of moving the lids and shielding radiation.
TEPCO begins studying dislodged reactor cover
July 18, 2019
The operator of the damaged Fukushima Daiichi nuclear power plant has begun a robot survey of a dislodged cover of the facility’s No.1 reactor containment vessel. High radiation leaking from the area is hindering Tokyo Electric Power Company, or TEPCO, from carrying out decommissioning work.
The roughly 500-ton, three-layer cover was dislodged by a hydrogen explosion after the March 2011 earthquake and tsunami.
Around the cover, radiation levels as high as 2.23 sieverts per hour have been detected.
TEPCO plans to remove 392 nuclear fuel assemblies from a cooling pool next to the reactor container.
But workers must either put the cover back in place or install a shield to lower radiation levels before starting the work.
The firm began examining the dislodged cover on Wednesday.
Engineers are sending robots between the cover’s top and middle sections to conduct 3D scanning and collect samples of radioactive material from its surface.
TEPCO is to continue the survey through early next month and consider what needs to be done.

July 27, 2019 - Posted by | fukushima 2019 | ,

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