And apparently, it has been for two months, according to the latest reports:

It appears that the entire active fuel region of the core, when in normal condition, is exposed .. i.e. not covered with water. It may not have been since nearly the start of the casualty.

Some of the fuel has very likely melted and dropped into the lower pressure vessel head area. BWR reactors, because of their power profile, would be expected to experience fuel element melt from the center outward over a span of time without cooling. TEPCO has not given a clue as to how much of the fuel is damaged, but we noted the reduction a few weeks ago in the estimated percentage from 70% down to 55% and wonder if this won't get moved back up. Perhaps higher.

Apparently the melted fuel, known as "corium," is sitting in the bottom of the reactor vessel and being cooled by whatever water they are managing to get into a puddle at the bottom. With 5-point earthquakes continuing to pop off with regularity in the vicinity, there's still the potential for a major melt through the containment. Another big dirty bomb moment is by no means out of the question.