An evacuated zone 30 km around the reactor
This map of radioactive deposits (measured by activity of cesium-137 in soil), in the immediate vicinity of the damaged reactor at Chernobyl, shows very high contaminations but very uneven. Activity exceeds 3700 kBq per square meter near the reactor and the city of Pripyat (40 times the dose rate of natural radioactivity). These contaminations have led, on April 27, 1986, to the evacuation by the Soviet authorities of 116,000 people living within a circle of 30 km radius.
UNSCEAR-2000