The problem with fission reactors, is that the accidents can have terrible effects in any part of the world. An explosion causes heavily contaminated material to be released at high altitude, where the winds can transport them pretty much anywhere. The melt rods eat tru any material and reach and contaminate subterranean waters. That's why everyone was so scared about Chernobyl, and Fukushima (not so long ago).
The Chernobyl accident has been studied in detail for over 30 years now, and we have a lot of scientific data on what actually happened. Worst case estimates say that about a total of 30'000 might die prematurely in Europe because of radioactive particles from Chernobyl (many others like the IAEA and the WHO says it's 4'000). Thankfully such accidents happens very seldom; since the first nuclear reactors were built in the 1940s it has only happened twice (and Fukushima is believed to have less of an health impact than Chernobyl).
That still sounds really bad! But what many forget is that the alternatives are not without risk either.
For example, the worst hydro electric dam accident killed ~171000 people.
https://en.wikipedia.org/wiki/Banqiao_DamThat did only affect the country that built the dam though, so you could say it was more local.
But what about wood stoves? You posted a link before:
https://unstats.un.org/sdgs/report/2018/overview/It says that: "In 2016, household and outdoor air pollution led to some 7 million deaths worldwide." (!)
That air pollution comes from burning and it's killing millions every year. If you replaced that burning with electric power from nuclear we will literally save millions of lives every year all around the world.
Wood stoves also spread their air-pollution around the world. So does any form of burning, it causes air-pollution which is spread with the wind around the world in the same way the Chernobyl accident spread radioactive particles with the wind.
That UN page doesn't say how many of the 7 million deaths are cause by wood stoves, but I know a Swedish report that estimate that 900 died prematurely in Sweden because of wood burning. (We have a population of about 10 million). That means that only in Sweden wood burning causes more deaths in 4 - 35 years than the biggest nuclear disaster did worldwide over all time. The same report says that a total of 7600 die every year from air pollution here, and that 3600 of them are caused by air pollution that comes from outside of Sweden (e.g. coal power plants).
http://naturvardsverket.diva-portal.org/smash/get/diva2:1242584/FULLTEXT01.pdfAnd then we haven't even considered all the other toxins from coal power plants, like mercury and other heavy metals. Or the problem with ocean acidification (caused by SO
2 as well as CO
2 from coal power plants). Those effects are also global; it's the reason why ocean tuna contains so much mercury for example, or why the great barrier reef is dying. And then there is climate change, which also affects the entire planet...
So yes, a nuclear accident can cause pollution in other countries but it is nothing compared to what air pollution from burning does.