a) hefty chunks of the fuel rods are exposed to the air in reactors 1, 2 and 3
b) there's no information on spent fuel pool temperatures in reactors 1, 3 and 4 (2 is OK at 28C).
c) there seems to be uncertainty about the sources of the smoke observed at all four reactors. Yesterday 1, 2 and 4 were all emitting, 3 was emitting the day before.
d) pressure in #1 is far higher than in 2 or 3.
NHK reports that there's highly radioactive water in the basements of 1 and 3 - not totally surprising given they're being sprayed. TEPCO's latest assessment of the reactors says that the company believes of reactors 4, 5 and 6 that "we do not consider any reactor coolant leakage inside the reactor happened", while remaining silent on 1, 2 and 3. Some are interpreting the radioactive water as the result of a possible breach.
"Water was also discovered in Units 2 and 4, and the company said it suspects that, too, is radioactive. Officials acknowledged the water would delay work inside the plant.
Plant officials and government regulators say they don't know the source of the radioactive water discovered at Units 1 and 3. It could have come from a leaking reactor core, associated pipes, or a spent fuel pool. Or it may be the result of overfilling the pools with emergency cooling water."
I get the impression that the 'injection' of water and seawater into the cores is not accompanied (deliberately, at any rate) by removal of hot water from the cores. Looks like they're just pumping more in. I can see that will reduce pressure in the short term as the temperature drops, but surely that can't go on indefinitely? Yet apparently the fuel is still exposed - where's all the water going? Hopefully not the basement.
Looks like the struggle continues, with number 3 being the beast to tame, because of the plutonium hazard. Best of luck, lads (and lasses - there's at least one woman on the team).