My understanding is that this whole problem was created because the tsunami knocked out the diesel generators, correct?
My question is simple. Why were they unable to replace them with a mobile generator within a matter of hours?
Surely you'd allow for an obvious contingency like that, wouldn't you?
In the film industry we use generator trucks all the time with substantial electrical output. Our army has generators mounted on 4WD Unimog trucks that can drive through water pretty much up to the top of the cabin (it's generally a good idea to leave a little gap at the top so the driver can see).
California nuclear plants have truck mounted generators offsite for just that contingency.
Commercial power is available a short distance away. It shouldn't take more than a day or two to connect the reactors to power. But construction only started yesterday.
