The full Monty can be had by reading the lead-in article to that thread. Pretty much 'splains everything away.
Bottom Line: the Japs got it covered and there's really nothing to see here; this is bunch of hysteria mongered by the anti-nuke crowd. Unless they totally misengineered this thing (probably forgot to carry the two or sumpin'), there's more'n enough mass water in the primary loop to cool the reactor core to below crtical temp. That is unless something went horribly awry with the primary reactor containment vessel and significant mass of primary coolant loop water was lost. But, if that's true, the radiation counters be going Ah-OOOOH-Gah! Ah-OOOOOH-Gah! BIG TIME to grimace proportion.
japan has hundreds of earthquakes a year. if a fire caused by a quake in the pool at unit 4 broke out & spread igniting the irradiated fuel throughout the nuclear site it would release an amount of cesium-137 equaling a doomsday load, 85 times more than the release at Chernobyl.