Poor design (backup generators for a seaside plant, in a floodable basement), technically clueless management (I bet you they're all lawyers and MBAs with no nuclear engineers) in a panic. TEPCO has a history of forged plant safety reports... As I said in other comments,

Everyone can crack jokes about Soviet technology, but if this happens to the Japanese we can stop feeling all smug about French and Swedish reactors.

Not unlike the way the 1997/8 Asian/Russian financial crisis couldn't happen to the "sophisticated" WestTM, and look at the ongoing Global Financial Clusterfuck.

So, in what may be my last act of "advising", I'll advise you to cut the jargon. -- My old PhD advisor, to me, 26/2/11