Conditions inside Fukushima's ruined reactors still unclear after 13 years

The contents of the three reactors is still largely a mystery. Little is known, for instance, about the melted fuel’s condition or exactly where it’s located in the reactors. Not even a spoonful of the fuel has been removed yet.

About 880 tons of melted nuclear fuel remain inside the three damaged reactors, and Japanese officials say removing it would take 30-40 years. Experts call that timeline overly optimistic. The amount of melted fuel is 10 times that removed from Three Mile Island following its 1979 partial core melt.