If we can’t even count on the Japanese to be competent, uncorrupt, and forward looking so such an event would have never happened then we’re in for a world of hurt.
No one could have foreseen an event like that tsunami.
I am not certain any corruption was involved but there was a severe lack of safety and hazardous analysis thinking.
Today modern safety engineers develop analyses that consider the type of things that might go wrong. The consideration of a tsunami that was higher than ever seen would be understood. Storage of spent fuel rods would never be undertaken in the same area as the reactor and certainly would not be stored where water could accumulate and cover the fuel rods. I would also think the wall would have been built higher, (maybe some corruption was involved in the desire to avoid the expense, I do not know.)
However, we will need nuclear power soon, (if not already) and the cost of doing it right must be applied. People have looked at the density of other carbon free alternatives and they take over the countryside because of their low density. We will need the higher density in many places.
Fukushima happened due to an act of God; an earthquake and a massive tsunami accompanying it. There was nothing more they could have done to protect that power plant, and I understand that it was up to par when it came to safety.
This was not a Japanese version of Chernobyl.