For some animals yes, but not for all. It seems that for some birds is more like a sink, constantly recolonized by birds from other zones that die quickly. Chernobil is unique in many aspects, as a defy, an economic burden for all european countries and an opportunity. I think that should be declared as the first supranational european park, watched and cleaned as soon as possible. Radioactive animals living in Chernobyl travel across all europe and migrate towards the nord also so is a problem for EU, and also for the countries belonging to the old Soviet Union that can't be managed for one single country.