One major mystery — and a source of serious concern — at the Fukushima No. 1 nuclear plant is the exact location of the molten fuel from reactors 1, 2 and 3.
Hindered by the dangerously high radiation coming from the melted rods, Tokyo Electric Power Co. can't determine where the fuel came to rest. Tepco does say, however, that computer simulations indicate the fuel should still be inside the reactors' primary containment vessels.
One solution may be found with a Nagoya-based scientist group that is working on capturing images from inside nuclear plant reactors, much like X-ray photos, by using muon cosmic rays.