[Short Column] Where is the molten fuel ?

People often ask me about where I think the molten fuel is.

I assumption is this, the fuel assemblies are entirely molten a few hours after the station power blackout in 311. When they vented the vessels, a part of the molten fuel splashed out of the primary containment vessels, could be even out of the venting stacks.

The rest of the fuel was scattered everywhere in the vessels and the reactor buildings due to the explosion. Some of them might be in the base concrete.
Currently those are moving with coolant water, and are in individual stages of fission reactions, which are small enough not to be detected outside of the plant area.

The decay power probably isn’t large enough to cause additional hydrovolcanic explosion anymore, but widely scattered fuel is making decommissioning more difficult.