the reactors at fukishima were past their shut down date. they weathered an earthquake a full order of magnitude larger than anyone thought possible. then they weathered a direct hit from a tsunami. then they weathered a loss of power. it was only the secondary loss of power brought on by human inability to get power back up and running that caused this disaster. a second set of deisals (which are at all US sites and are now being installed at all Japanese ones), and the only stories we'd be hearing from Japan today is the 'painfully-a-nation-rebuilds' variety.
and the radiation from this Level 7 event is so far - in total - a little less than 10% of that which was put out at Chernobyl.