The high-definition color images captured by the drones show brown objects with various shapes and sizes dangling from various locations in the pedestal. Parts of the control-rod drive mechanism, which controls the nuclear chain reaction, and other equipment attached to the core were dislodged.TEPCO officials said they were unable to tell from the images whether the dangling lumps were melted fuel or melted equipment without obtaining other data such as radiation levels. The drones did not carry dosimeters to measure radiation because they had to be lightweight and maneuverable.The drone cameras could not see the bottom of the reactor core, in part because of the darkness of the containment vessel, officials said. Information from the probe could help future investigations of the melted debris which are key to developing technologies and robots for its removal, they said.But the large amount that remains unknown about the interior of the reactors suggests how difficult it will be. Critics say the 30-40 year target for the plant’s cleanup set by the government and TEPCO is overly optimistic.The daunting decommissioning process has already been delayed for years by technical hurdles and the lack of data.



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