In the case of Fukushima, the critical generators could have been moved to a higher location without a major redesign of the plant.
At the core of most of these disasters is the cost element that was traded against what level of risk could be reasonably defended in the case of an actual disaster. This is why industries are often not allowed to regulate themselves; their financial incentives are invariably overly skewed in the opposite direction of safety and conservatism.
TTFN (ta ta for now)
I can do absolutely anything. I'm an expert!
Maybe a small point as regards to the flooding of the Missouri river, but maybe the Army Corp should have looked a little farther ahead as to what happens to the nuclear station downstream if the reservoirs are too full and need to dump water like crazy to avoid overtopping.