For those stressing about a nucrear dirty bomb, read
this. The article gives a full explanation of just what the hell is happening The hard part is just keeping it cool enough while the "background" reaction winds down over a couple of weeks (which according to the article, as long as things are kept under control, isn't a big issue). However "under control" is appearing to be something of a challenge, which I'm crossing my fingers about them can keep up to the job for the next fortnight while this thing spools down.
From what i've read of that article the reaction itself has stopped with a minute or two of the rods being pushed in to stop the reaction. It's just that they have to keep it cool enough while the cesium & other "decay products" break down into stable material. Think of it this way, the thermal load of the background reaction while a plant winds down is 3% of its 100% capacity load, they have to pump enough coolant through there while this process dissipates this residual energy. Given that the batteries are flat, the generators were wiped out and they have no power being generated by other reactors onsite, this is turning out to be harder than anticipated.
For those that cbf with reading the link, as i understand it one big difference between Chernobyl and this aside from the poor design of Chernobyl & the procedures (not) followed is that they had problems with the coolant while OPERATIONAL and then on top of that had issues with deploying the control rods. Hence the reactor went into meltdown as the rod casings hit their 2200'c melting point and then the fuel started melting (at about 3,500'c) and effectively melted through the concrete in a nice big pool. This caused a crapload of steam to build in the internal chamber and kablooie as it didn't vent correctly.
Still, there area a few stories, some more up to date than others, an earlier one
here gives a bit more gloom and doom, but one from
this evening is a lot more optimistic. Though there's a few threads raging along on advrider with people saying they are dropping everything and going to the east coast for a while.