They have done that! There is an exclusion zone around Chernobyl of 30 kilometres (19 miles).
Chain-linked Fenced in and warning signs in multiple languages all around.
A couple of years back, an international team of scientists were allowed in to do surveys of the area and see what has happened to the wildlife.
They were dumbfounded!
There not only was plentiful wildlife, but it was thriving!
Every kind of wildlife, birds, rabbits, mice, moose, bear, fox and anything else you can imagine. Trees and plant life was fully recovered where the trees had all died.
Everything was radioactive way beyond what is considered to be safe and healthy exposure!
Why, they wondered?
Then it dawned on them:
All these things die of natural age-related things before the radiation has an affect that would kill them. They don’t live long enough for the radiation to become a problem.
Now, humans with a much longer lifespan would have a problem living there, but still might live to be 40-50 years..............
Nope,
The radioactive Iodine, which was by far the most radioactive element released, and was really the only dangerous product of the reactor has half time of 8 days.
It is gone a very long time ago, few before one year passed!
The radioactive cesium (not really that dangerous) has half time 30 years, so even this is mostly gone. There is some radioactive plutonium there with half time 12,000 years.
So
Is there some trace radioactivity attributable to the reactor accident? Answer is definitely YES!
Will there be some traces of radioactivity detectable in long future? Yes!
Does it matter for the human life and well being? NO!
The data, I have available, shows levels of radioactivity well below the safe levels in the vast majority of the exclusion zone!
Whole area is safe for short visits, but there are few small areas, where I would not go to live for long time.
Back of the reactor, basement of Pripyat hospital, cemetery, some stairs somewhere.
Most of it could be easily cleaned and/or fenced off.
The rest of the exclusion zone has levels which are completely safe for humans to stay. It should be declared safe and repopulated!
About 30 years ago!