Chernobyl now receives over 10,000 tourists a year and this number tends to grow. So numbers
answer on a question "is it safe?" by themselves.
Here are some more numbers: radiation is measured in sieverts, and during a Chernobyl tour,
if you take Geiger counter you will face 130 to 2610 microsieverts p/h which is
similar to the radiation level that people take during long flights.