Which specific issue ? That the explosions occurred as the molten fuel was leaving the RPV ?
Is this what you’re relying on for facts?
“Once power was lost, critical functions like the cooling system shut down, as did the instruments that told workers what was happening inside the reactors. Three of the reactors quickly overheated, causing meltdowns that eventually led to explosions, which hurled large amounts of radioactive material into the air.”
This is from the New York Times - Asia/Pacific, June 1, 2011. They are no more a reputable source of information on nuclear matters than they are on political matters.
I will repeat - nuclear fuel cannot explode. See Wikipedia: Criticalisty Accident
http://en.wikipedia.org/wiki/Nuclear_excursion