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 …