WHERE DID THE MATERIAL THAT ESCAPED GO?
At the time of the accident the weather at Chernobyl was fine cool and calm. The hot gases and particulates rose straight up to high altitude before moving slowly north-west. This prevented excessive fall out close to the power plant.
A rapid change in the weather then occurred. This caused the radioactive cloud to split into three fingers. the first moved NW towards Sweden. the second moved SW and the third (at highest altitude) moved NE and eventually crossed Japan.
The SW cloud changed direction over France to go NW and cross the UK on the 3rd May (depositing most radiation on Sellafield!). After further splitting the cloud doubled back across the UK on May 7th