What really caused the Reactor problems...

When the earthquake happened the reactors shut down like they were supposed to and at first all was well.  Then the tsunami took out power and the backup generators (or more specifically their fuel tanks). At this point the battery fall back system cut in.  This also worked for a while.  It had only 8 hours power reserve but the Japan defense force successfully brought in more batteries (and extra generator/fuel capacity) All Should have been well, a scandal re placement of the generators/fuel but No serious nuclear issues.

Then everything started failing.  Coolant pumps and various valves broke, stopped working or went haywire.  From there all the rest of the disaster unfolded.  It must be understood that when it all started coming undone there was Very little physical damage to the plant and everything was functioning as planned on back-up electric batteries.  Those batteries did not run out of power.

I believe that the only reasonable explanation for that series of events is an attack by a Worm/virus called Stuxnet which is designed Specificly to attack industrial control systems and in particular those in reactors/nuclear plants.  Even More specifically reactors using the systems used here in this case.

This malware was created by Israel and the US to attack Iran's nuclear program.  It successfully set Iran back years by destroying their centrifuge machines that were enriching uranium.  The malware is extremely virulent and hard to detect or eradicate.  It creates physical damage to motors etc by causing them to speed out of control.  It BREAKS things.  

  It was first detected in Japan in october last year. But it has now spread all over the world. That is why countries like Germany, South Africa and many others that operate similar reactors have shut them down for "Safety Checks" - basically a large percent of the worlds nuclear power supply Must now be considered EXTREMELY Dangerous.

They are freaking out.  Nobody is sure the thing can ever be eliminated.

P.s. There is some credibility to the idea that Stuxnet contributed to or caused the equipment failures that created the Gulf Oil Spill.