[driftdiver]

“Looks like there must have been some fuel damage if they are still getting hydrogen explosions, like at the No. 3 unit recently. “

As I understand it the hydrogen is caused by the high pressure/temperatures of the water being used as coolant. Under those conditions the water seperates into oxygen and Hydrogen.

Fuel damage would be indicated by detection of radioactive Cesium or Iodine. There apparently has been a small amount of fuel damage as coolant levels became low. However the reactors have been shutdown for a while now so the risk of a “meltdown” is decreasing.

[chimera]

Certainly the heat load will drop as the fission products decay, so time is on our side in that sense. They'll still need to keep those fuel assemblies covered.

Thermal dissociation of hydrogen and oxygen in water would still indicate pretty high temperatures. What is the minimum temperature for that to occur and does it exceed the melting point of the cladding? If so, then yes, some or maybe all of the hydrogen could be generated in that fashion.