It seems all the reactors were successfully shut down - i.e. the fuel is now intermixed with rods of neutron-absorbing material. They can't go critical (bomb-style explosion). What's generating the heat is decay of fission products.

IF everything can be kept under control for a day or two, things get a lot more manageable, as the decay energy of the fission products drops off quite quickly.

Still a godawful mess to deal with afterwards, probably about as expensive as Chernobyl. No chance that a private company would have the funds to fix the damage. Anybody know about TEPCO's ownership?