RADIOACTIVITY CHERNOBYL, Exclusion zone. Ukraine. Workers travelling by Bus to and from the plant. Eve of the 20th Anniversary of the fire in reactor 4 at Chernobyl power station in 1986. The fire started in the early hours of the 26th April 1986, The radioactive cloud dispersed worldwide. 250 thousand were evacuated. Exclusion zones exist in close vicinity of Chernobyl in Ukraine and Belarus where people will not be able to live for tens of thousands of years.