Because they lost power to the water cooling system, they needed to vent the pressure that's building up inside.My suspicion is that as the temperature inside the reactor was rising, some of the metal cans that surround the fuel may have burst and at high temperature, that fuel cladding can react with water to produce zirconium oxide and hydrogen.That hydrogen then will be part of the gases that need to be vented. That hydrogen then mixes with the surrounding air. Hydrogen and oxygen can then recombine explosively. So it seems while the explosion wasn't directly connected with the nuclear processes, it was indirectly connected, because the hydrogen was only present because of what was going on in the reactor core.
quote: Please explain.
quote: Why is it that you believe that it's more difficult to contain a pebble bed design than currently extant types of reactors? And given that the problems a pebble bed addresses are precisely the ones that threaten containment in the current Japanese situation, why would it be more dangerous in a case like this?
quote: What new safeguards on legacy reactors do you suggest would solve the problems the Japanese face?