Caption: 
From left, the SwRI drone hovers next to an orange crane used to lower fuel rods into a containment vessel. Middle, a LIDAR image shows the drone’s point of view as it hovers above the containment vessel entrance (blue/green circle) and crane (orange rectangle). The dark rectangle at bottom right is a ventilation shaft. Right, the drone flew in the ventilation shaft, traveling 40 meters vertically to the area housing the crane. A radiation detector aboard the drone identified Cobalt-60, a radioisotope, in a red pipe located in the shaft.