Nuclear polution is a non-issue for the natural environment. The Chernobyl explosion was the best thing that could have happened to the local fauna and flora. All those pesky human beings and their destructive habits, like agriculture, have gone from the area and the local wildlife is thriving. These days there is no real detectable evidence of any adverse effects to wildlife other than very close to the reactor. Of course wildlife is not too concerned about relatively small increases in some cancers - it's just another relatively small element to add to the already high mortality. However, human beings don't feel quite that way, especially as these days we expect to live to (by natural standards) exceptionally long lives.
It's always a big mistake to confuse human interests with those of other creatures. If we stopped fishing an area due to a fear of ingesting nuclear contamination, then the natural world will be happily clapping their flippers and fins together. It's industrial fishing and human displacement that affects them - not the relatively minor issue of a little bit of background radioactive contamination. An all-out nuclear war might not be quite the same thing, but that's not the issue here.
This was James Lovelock's take on nuclear contamination
"A television interviewer once asked me, 'But what about nuclear waste? Will it not poison the whole biosphere and persist for millions of years? ' I knew this to be a nightmare fantasy wholly without substance in the real world... One of the striking things about places heavily contaminated by radioactive nuclides is the richness of their wildlife. This is true of the land around Chernobyl, the bomb test sites of the Pacific, and areas near the United States' Savannah River nuclear weapons plant of the Second World War. Wild plants and animals do not perceive radiation as dangerous, and any slight reduction it may cause in their lifespans is far less a hazard than is the presence of people and their pets...
Now I'm not one of those who decry green issues as many of the commentors on this site appear to be. However, I'm no fan of the new-age, head in the clouds, sentimentalised stuff that a lot of so-called environmentalists trot out as truth.