"We'll go on battery backup for 8 hours"....which they did.
Maybe go down to Home Depot and bring back a whole crapload of Honda generators, I guess?
The generators are the size of locomotive engines.
The plant didn't fail: The diesel generators did.
And informed sources say the main power panels and switches for them were below ground....and were swamped with water after it breached the dike specifically built for a 5 meter tsunami. Next question?
So, I’d call that an unsuitable emergency deployment plan and faulty design.