There was a report on Chernobyl the other day. Apparently, the nature there is experiencing a renaissance of sorts with a measurable growth both in biodiversity as well as in the sheer number of species, including endangered ones.
For animal world, the radiation is the lesser of two evils, the first one being humans.
Only slightly related is the excellent Arkady Renko novel Wolves Eat Dogs which is partly set in the Chernobyl exclusion zone (and touches on the wolves that have taken over that area):
My first thought after reading about the wildlife around Chernobyl many years ago was that Greenpeace or similar groups should arrange 'accidental' radiation spills in threatened environments. Good for a few decades of protection.
It's worth remembering that hundreds of thousands of people's work and billions of dollars have been spent trying to reduce the surface radiation levels around Chernobyl. A huge amount of earth was moved to bury surface radiation. Chernobyl 01:23:40 goes into a lot of detail about the sheer scale of work that was poured into the cleanup project.
It's easy to get romantic about nature, animals, biodiversity etc. but if that work had not been done the situation today would be a lot less inspiring.
Humans have also created a lot. Domestic animal breeds for example. Nature left to it's own devices does not always do better than it does under the stewardship of humans. A garden is a simple example.
"Better" means nothing in this context anyway. Domestic breeds do not "do better" in some global sense either... often they do much worse on their own. You need to trim a horse or sheep's hooves. You need to check them for parasites. They need vaccines and antibiotics, and a tailored diet.
They're great for what we bred them for... live fat, die young... they're terrible in the wild. When you see pigs in the wild, they rapidly return to "boar" states, and lose those lovely "piggy" qualities you see on a small farm. Corn is great... for us. Without us, it all dies and can't reproduce alone.
A garden isn't our creation, it's our specific modification to suit our specific needs. It serves only us, and those forms of life which can adapt to us. It's also wildly artificial, requiring chemicals, or constant attention to achieve the "garden" state. A tulip is only "better" in a garden because it's one of the organisms we permit to live in the garden. Obviously the dandelions are much "better" overall though, because given a month alone it will be their garden, and not the tulips'.
The radiation levels near Chernobyl probably aren't that bad anyway; if you lived there, you could probably expect to die of cancer 2-3 decades earlier than normal, I'm guessing. So expect to die at 40-55 maybe. For modern humans, that doesn't sound all that appealing, so we stay away.
But animals don't live that long in the wild typically anyway, and tend to reproduce fairly quickly. So dying of cancer in middle-age probably isn't all that noticeable to them, because they're probably going to die by then anyway, or either accident or predation or (non-radiation-related) disease.
2-3x is likely an overestimate. That may be a good estimate for people who actually lived at the time of the incident, but not for anyone living there today.
For animal world, the radiation is the lesser of two evils, the first one being humans.
Here's a BBC article: http://www.bbc.com/russian/science/2015/02/150205_ukraine_ch...
It's in Russian, but the pictures are telling if you can't read it.