Exclusion zone is a human concept for human inhabitation, it does not mean the zone is lost from the map of Ukraine. According to scientists that study the zone, for the non-human ecosystem the benefits of people moving out outweigh the damage now. In time, the radiation will go down so people can live there. Some already do, even though it is illegal.
https://www.telegraph.co.uk/news/2016/04/23/wildlife-returns...
Okay, well, aside from the 4000–60'000 people who died from the Chernobyl disaster, 350'000 people permanently lost their homes, so they were significantly harmed. What "other industrial accidents, like chemical plants or oil/gas" is that "very small" compared to? What non-nuclear industrial accidents have permanently uprooted (or otherwise "significantly harmed") 700'000 or more people, wiping out entire centuries-old communities? Even the Beirut Blast (300,000 homeless, 210 dead, 7500 injured) and the Bhopal disaster (2500–16000 dead, 500'000 injured) didn't manage that.
It's probably true that the deer, rabbits, and black mold are better off, even if the people aren't, and that might be a good reason for deer, rabbits, and black mold to build nuclear power plants. But it's not a very convincing reason for people to build nuclear power plants.
(Global warming was, though, or should have been, until we had the better alternatives we have now.)
Hmm, it's been 35 years and При́пʼять is still uninhabited—and, I think, uninhabitable—as part of the 2600-square-kilometer Chernobyl Exclusion Zone. Which chemical-plant or oil/gas industrial accidents are you thinking of that have rendered 5000 square kilometers uninhabitable for 35 years, or rendered 2600 square kilometers uninhabitable for 70 years? I'm supposing that "very small when you compare" implies at least a factor of 2—more likely a factor of 10?
I can't even think of any major wars that have had such an effect, although it's easy to think of wars and accidents that have killed more people. Chernobyl killed 100 people more or less immediately and several thousand more people over the years. The Fukushima accident itself has only killed one person so far, but the evacuation (to keep people from being killed by radioactivity) killed 2200 more people.
On the afternoon that При́пʼять was evacuated in 01986, it was the ninth atomgrad; today there are 11 atomgrads in Russia (ЗАТО under the authority of Росатом), producing 20% of Russia's electricity. If we had five times as many atomgrads, or if we had as many atomgrads as we have sites of chemical plants, how many uninhabitable atomic Exclusion Zones would we have by now? Would it be more, or—thanks to the extra experience—fewer? Surely some would be smaller than Chernobyl's, some larger.
I think there probably would have been a few hundred thousand more people dead in such accidents, and a few dozen more radioactive nature preserves like the Chernobyl zone, before we figured it out, and that would have been better than the global-warming catastrophe we were on track for a decade ago. For better or worse, though, that wasn't the way things went. Instead now we have solar energy that's not just cheaper than nuclear but cheaper than coal.