What I find amazing is the poor planing for emergencies. The whole disaster was a result of no cooling water for the reactor due to damage from the quake. I will never understand why the reactor was not designed to have a backup system with its own independent power source to pump cooling water in an emergency.
All it would have taken is a couple of diesel engines and pumps. These are cheap. They had a whole damn ocean of water to use if necessary.
The earthquake didn't take out the reactors. The resulting tsunami flooded the emergency generators and knocked them out of action. And when you think about it, earthquakes and tsunamis are not disjoint events so this probably should have been foreseen.
It did. As a matter of fact each reactor had three diesel generators (DG) to supply power to the emergency cooling water systems.
Unfortunately the DG’s and the electrical busses that they fed were swamped by the Tsunami. The DG’s and the electrical busses were in the plants basement.
When the tsunami hit the flood water filled the basement knocking out the emergency DGs and the electrical busses.