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Just the title is hilarious... regarding the No. 4 hydrogen explosion, see upthread.

Overheated open fuel pools cannot produce hydrogen because in an open fuel pool the water boils off at 100 Celsius, and won't be present in pressurized form at 2,000 degrees Celsius to liberate it's hydrogen by losing it's oxygen to the zircon cladding in the fuel rods.The rods will prefer the free oxygen in the air and burn long before attempting to claim the oxygen in whatever humidity there might be.

Just to piece together all that has been mixed up above:

  • 2,000°C was the estimated maximum temperature of exposed fuel rods in the core of some of the reactors, not the reaction temperature of steam;
  • the zircalloy cladding starts reacting with water below 800°C,
  • unlike zirconium powder, zircalloy cladding will not burn (it will oxidise alright, but will not ignite even at melting temperature),
  • pressure is less relevant to reaction rate than density, and less density doesn't mean no reaction just slower reaction,
  • water evaporating from the pool and rising up in it is very well present to react with the fuel rods,
  • however, the current theory abiout the origin of the exploded hydrogen is no more the spent fuel pool (its evaporation wasn't as dramatic by the time of the explosion), but hydrogen from No. 3: the venting pipes of both No. 3 and No. 4 unite and exit into the same exhaust stack, thus part of the hydrogen exiting No. 3 could  flow 'in reverse' into No. 4.

*Lunatic*, n.
One whose delusions are out of fashion.
by DoDo on Mon Jun 13th, 2011 at 09:31:20 AM EST
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