The question is how bad could a nuclear disaster be? What is worst case scenario?
Aside from the danger from tsunamis, Fukushima had the 'luck' to be near water as water absorbs radiation quite effectively. People have calculated that if that radiation is diffused evenly in the ocean, that it would not pose a threat. But it did not diffuse evenly and probably is now part of some food chain as well. Tracking it is quite difficult.
But it isn't just disasters, processing plants are not allowed to dump barrels into the ocean anymore, but they very well are allowed to dump their waste water. Cancer rates are significantly increased in these regions. Uranium is a finite resources as well, at least in economical proportions and even then the energy is quite expensive. Building a plant takes decades.
Only this or last year we got the first and still only permanent storage of used nuclear fuel. Some people say the problem is solved, but it isn't really. Yes, you could dump it in an old salt mines. That was done and the ground water got contaminated so it has to be waste has to be excavated which in turn will again cost billions.
The estimation of amount of victims depends on who you ask. There's no dispute about ~30 people who died of radiation. There is a huge dispute about others, with figures going all the way between tens of thousands and about a million.
In Fukushima's case, it's also argued that more people died as a result of evacuation than would have died of radiation (if no evacuation would have been ordered).
Pro-nuclear groups pull their estimates to one side, anti-nuclear to the opposite side.
https://www.seas.harvard.edu/news/2021/02/deaths-fossil-fuel...