Photo : Drone exploring over the cover of Reactor 2 PCV by Nuclear Regulation Authority [URL]
On the 8th of September, 2021, Nuclear Regulation Authority announced that a drone detected 1.1 Sv/h outside the vessel of Reactor 2. This is over 1,000 times higher than the annual safety limit for ordinary people.
The drone explored over the upper cover of the primary containment vessel (PCV) of Reactor 2. The cover is made of concrete and 12m in diameter.
Despite the shielding effect of the thickness of the concrete, the high level of radiation was measured in a 5cm deep hole, which the drone drilled on the cover.
It is estimated that a significant volume of scattered molten fuel is attached inside the concrete cover. The Nuclear Regulation Authority commented that this is going to be an extremely serious obstacle to proceed with decommissioning.
Video : Unit 2 reactor building operating floor at TEPCO’s Fukushima Daiichi NPS by Nuclear Regulation Authority in Japan.