One of two pressure sustain pools that are below the reactor has registered as equal to atmosphere, which leads them to believe it has ruptured and this where the possible leak is, though it has not been confirmed that there is for sure a leak.

However, they believe the pressure in the above reactor (and the other pressure sustaining pool) are still intact, meaning no rupture there.

Yesterday, the fuel rods were completely out of the water (pumped in seawater) and not being cooled for several hours, but it now sounds like have been able to pump water in again and now the rods are now half immersed in water (completely immersed is preferable). The more the rods are cooled (and they have been cooling on and off, depending on whether or not they could get sea water pumped in) the better long term prospects look. But we are dealing with mini sun like temperatures, so it takes a long time for the cool down. If they can't continue the cooling process (and boy have they hit a lot of roadblocks) the remaining heat will build up, and meltdown.
_________________________
We are what we repeatedly do - Aristotle