The rods in Reactor 4 at Fukushima.  These are those they need to extract.  David Suzuki, esteemed Canadian scientist, has likened the job to pulling cigarettes from a crushed pack.  These rods cannot be taken out of the water in the cooling ponds, can't touch one another, and can't be subjected to or withstand any earthquakes.  This is all of our problem, and if an earthquake does hit, scientists are predicting the evacuation of the entire west coast of North America (Japan too).