That tsunami killed 20.000+ people, and spilled massive amounts of chemicals and toxic junk to the ocean.

Yet people keep fixating over the radioactive pollution, including evicting people from their homes for truly minor amounts of radiation.

Turns out the "worst case scenario" of nuclear accidents is jackpot for nature. By clearing Fukushima from humans, nature is thriving: https://www.sciencealert.com/animals-aren-t-just-surviving-i...

The main reason is a combination of negligence by the owner of the plant and not enough enforcement of standards. The fukushima powerplant was known to have sea wall lower then required and as such was vulnerable to a tsunami (this was known for quite a long time) Combined with backup power in the basement (also against standards)

For an example of what happens to a reactor build according to safety requirements see the onagawa nuclear powerplant

Japan is very in the east, they said western designs. The reactor knows where it is, by knowing where it is not.

Just kidding.

Old, bad design - from the 1960s, in fact.