"The primary cause of Chernobyl was the instability of graphite moderated reactors at low power levels."
I recall seeing a year or so ago a documentary on Chernobyl. Aside from all the technological issues it seemed to me the main culpret was the political type guy that pushed the limits of the test the engineer's were running. As I recall the lead engineer walked off 'cuz of the politco's request knowing that it would cause a meltdown. The other engineers didn't and followed the politico's orders. (Or something to that effect!?)