Quite a few individuals, including Chris Busby and Arnie Gunderson, have stated they believe that ongoing fission is occurring at Fukushima. Knowledgeable commentators at Huffington Post and Enenews have also stated their belief in ongoing fission occurring at the plant.
That means that radiation is continuously being emitted from the plant and contaminating Japan, Canada, the US and the entire northern hemisphere.
There seems to exist considerable uncertainty about where the coriums actually reside at this point.
There is evidence that at least for units 1 and 2 the cores have melted through or are melting through the basements of the reactor buildings.
What happens then?
Does steam coming from the grounds mean the cores are fissioning underground and could come in contact with water, producing explosions?
I really do not know the answers to these questions, but they are worrisome.
Additionally, the site I've linked above has unconfirmed reports that there is a very large common spent fuel pool at Fukushima that contains or contained 6,400 spent nuclear fuel rods.
This situation is so terrible and it seems that every day we hear more bad news, which later becomes confirmed.
See CaptD at Huffington