On another board, people were saying that no reactor containment has been breached by any of the three explosions. The building shell is meant to keep the weather out, and is not part of the containment system, for those that don't know. Latest word from the IAEA is that Reactors 1, 2, and 3 are in cold shutdown, and no longer a danger. However, the vicinity of reactor 4 is now on fire. This is bad. You see, TEPCO did something very, very stupid: the spent fuel cooling pond drained and/or evaporated away in the days since the earthquake, and they didn't monitor it at all after the earthquake hit (!?). So, predictably, the rods heated up and ignited, spewing radioactive material into the atmosphere. Jesus. Latest radiation figure I could find was something like 8 Sv/hr (the IAEA says peak levels were around 400 mSv/hr).
At this point, Fukushima's design, and TEPCO's administration of it, seems pretty bad. Not because of anything in the reactor itself, but in the support structure around it. From what I've heard, someone had the bright idea to stick all the backup diesel generators in a low spot on the plant grounds, causing to all die in the tsunami. This wouldn't be so bad, since the battery backups all then engaged, and did give enough time for them to bring new diesels and other portable power sources in. Only problem? The plugs weren't the right type (!?!?). If you haven't facepalmed yet, you should. Then TEPCO concentrated so much on saving the damn reactors (ain't gonna do that without sufficient power, guys), they seem to have clean forgot that, oh hey, the spent fuel is really ****ing radioactive and gives off a lot of heat! So now we have this mess.
Despite all this, we should remember that even with all the stupidity, plus the fact that the facility was hit with a earthquake far stronger than it was designed for, and then got smacked by a ~10 m tsunami, for the reactors themselves, the worst we're looking at is a partial meltdown; indeed the main concern was whether the reactors would remain viable as power generators! The hydrogen explosions did jack and **** to the containment vessels, the safety systems all kicked in as designed. This is no Chernobyl. Not even close.
On a more somber note, it looks like the death toll in Japan is going to climb higher because of this incident. Because the quake's effects have been so widespread, much of the power grid in northeastern Honshu is offline, and it is now very difficult to effectively bring food, water, and shelter to the affected population due in part to the lack of electric power. Already, many people there are going into their fourth night without potable water, food, or heating. Bodies are washing ashore, and they can't burn them fast enough. At this point, if the death toll stops at 50,000 it'd be a blessing.