They didn't!!!!

It was just left to nature!!!!

Chernobyl is located in Ukraine and covers an area of approximately 2,600 square kilometers. The exclusion zone, the restricted area surrounding the Chernobyl Nuclear Power Plant, covers an area of about 2,200 square kilometers. Inside the exclusion zone, wildlife thrives and the abandoned city of Pripyat lies, making it a popular tourist destination.

At the time the Soviet Union still existed, the parts affected were Ukraine and Belarus mainly. Then anywhere north of there including Scandinavia, Poland, E Germany, the Baltic States. Of course the direct effects on the population tailed off with distance, but the meat from grazing animals was slightly affected and in many countries restrictions were applied to using this meat, these restrictions lasted many months. Even in the British Isles there were restrictions on meat from sheep for a while.