So I read...
Hydrogen burns in a flash, doesn’t itself explode but the heat generation could certainly cause water in the pool to flash to steam causing further reactions if the fuel assemblies are agitated.
Unit 3 was known to be using plutonium (MOX) in its mix for some of its fuel rods. Fuel ponds contain new and used fuel rods, some ‘spent’ waiting to be transferred to long term storage others ‘new’ waiting to be rotated into service inside the reactor. Plutonium is also a byproduct created inside the spent fuel rods to some small degree.
Why don’t they remove the fuel rods to another location? Because they must be kept underwater to be cooled at all time. Continuing residual heat from the used fuel rods in the assemblies is sufficient to cause them to heat up and catch fire and release their poisons in about 15 minutes, if exposed to ambient air. New/unused fuel rods are cold and could almost be handled by hand since they haven’t been exposed to a reaction yet (neutrons activity).
With Russia and the US agreeing to dismantle war heads, there was a sudden over supply of plutonium to either store or use. Selling it to nuclear power plant operators was one way to get rid of it.
The Savannah River Site is constructing a plant for reprocessing plutonium from warheads to sold as MOX nuclear fuel. After Fukushima, no government wants the stuff because it is highly unstable.
Witnesses reported hearing Unit 3’s explosions ten of miles away from it. Whether the long distance telephoto lens used to record the event had a stereo mike pickup is a mute point, there were explosions and sounds to go along with them.
Strontium in the fallout from Unit 3’s explosion indicates nuclear in nature, among the other types of fallout measured.
No NUCLEAR explosion...
Many things could have caused the explosion...but it wasn’t nuclear in nature.
In essence, you have a large dirty bomb sitting there—any explosion will distribute any adjacent radio nuclides into the atmosphere, which will then ‘fallout’ over the Earths surface depending on where the winds will take them. But it is simply NOT possible for there to be a ‘Nuclear Explosion’.
If they are building a plant to reprocess plutonium, why the HELL aren’t they building a plant (or plants) to reprocess all spent fuel rods from reactor plants? The Navy does it, and has never had an accident doing it for most of a half century now.