Peter Yanev, one of the world's best-known consultants on designing nuclear plants to withstand earthquakes, said the seawalls at the Japanese plants could not handle tsunami waves of the height that struck them. But the diesel generators were situated in a low spot on the assumption that the walls were high enough to protect against any likely tsunami.

That turned out to be a fatal miscalculation. The tsunami walls either should have been built higher, or the generators should have been place on higher ground to withstand potential flooding, he said.

As one who used to be in charge of installing emergency diesel generators in industrial plants and oil/gas rigs (that was long ago!), I can say emergency diesel generators are highly vulnerable. They must be located in safe places and well protected, and that includes the diesel fuel storage tanks and supply lines, the air intake system, the electric and/or compressed air starting devices, the batteries, the engine cooling system as well as the electric and electronic devices that are supposed to automatically start them and connect them to the pumps whenever there is a power shortage and to pilot them. So if they were flooded, there was no chance they could run for long.

"People only accept change when they are faced with necessity, and only recognize necessity when a crisis is upon them." - Jean Monnet