I really don't think Fukushima was that bad.   Over 10000 people died that day, and an estimated 3 have died because of the nuclear power plant.   You had a 1 out of 1000 year disaster.  It's unreasonable to presume that humans can be prepared for every scenario every time.  What happened at the plant was not pleasant, but is probably good enough.  I mean, sure, make some simple design changes, that is fine.  Live and learn, at some point you need to accept that bad things can happen, and move forward.