TEPCO’s Plan For Some Of The More Dangerous Work At Daiichi

Soon after the disaster workers at the plant discovered that their dosimeters would high radiation alarm then be unable to give a reading when they approached the unit 1-2 shared vent tower. This was an indication that radiation levels near the tower were so high that their dosimeters were unable to accurately read the level. One of the most dangerous places at Fukushima Daiichi may undergo work to reduce the ongoing risk.

One of the two units connected to this vent tower ejected considerable amounts of radioactive materials via the tower during the initial disaster. The area has been declared off limits with shielding walls installed. Closer inspection with cameras and drones showed that the tower had suffered structural damage and was at risk of collapse or further damage. Since then TEPCO and the research agencies tasked with disaster clean up at the site have been working on a plan to dismantle the tower.

The current plan includes a complex series of machines and equipment designed specifically for this task. The work would remove the upper portions of the vent tower then install a cap on the top of the remaining pipe. This is assumed to be used to prevent further release of radioactive materials or inflow of rainwater into the highly radioactive area. The actual demolition work is scheduled for fall of 2018 and could take a year to complete.

The graphic below shows the steps towards cutting down the tower in sections.

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Drone Inspection of Fukushima Units 1 & 2 Vent Tower

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TEPCO reported on October 20th they used drones to measure radioactivity at the  reactors 1 and 2 vent tower.

Vent towers are quite unstable during earthquakes and are highly contaminated, they are therefore not easy to dismantle, even with robot

When they sent a drone into the vent tower, they found out that a bar prevented the drone to go in lower than 10-20 m below.

It’s pretty amazing that Tepco did not know that this bar was there and that they can not give its position more precisely.

TEPCO only  provided two pictures online with a laconic comment. No results of their radioactivity measuring was given. Transparency is progressing …

http://www.tepco.co.jp/en/nu/fukushima-np/handouts/2016/images/handouts_161020_02-e.pdf