“To my knowledge, the world has never experienced a complete run away meltdown”
Your phraseology suggests a meltdown could somehow turn into an uncontrolled chain reaction, implying the core could be a nuclear bomb. Which is impossible. The worst it could be is something like a dirty bomb, what with the conventional explosions. But, really, people are worried about the fact that after whatever happens, there will be a hunk of radioactivity sitting in there, and if it gets out, it will be bad.
All I have to say is that we have no reason to believe it will get out. That is, in anything like deadly doses. If it does get out, we need to join the anti-nuke crowd, chant kumbaya, and pray to the Sun and Wind gods to supplement our energy needs. I doubt it will.
>>Your phraseology suggests a meltdown could somehow turn into an uncontrolled chain reaction, implying the core could be a nuclear bomb<<
No, that is not what I implied.