” Tepco admitted the molten fuel is transferred to multiple places in Reactor 2 by 6/30/2016.
Tepco had been implementing the muon scanning investigation with KEK (High Energy Accelerator Research Organization).
Tepco describes the research result as it is highly likely that major part of the molten nuclear fuel remains in the bottom of the reactor with structures of the inside of the reactor. They also detected a part of the molten fuel on the wall of the reactor. This means the molten fuel was separated and remaining in different locations. Tepco did not mention the percentage of the detected fuel.
Tepco did not identify the location either so it is not clear if the fuel remains inside of the Reactor Pressure Vessel or its outer structure, Primary Containment Vessel. ”
by Iori Mochizuki
source with French translation