Thread:Comments:Situation at damaged nuclear power plant remains 'very grave', says Japanese Prime Minister/boom/reply

Actually due to the way that such things spread, only a small area ever gets affected. IIRC the strength of a cloud of radiation (or any other cloud:P) decreases with the square of the distance, barring extenuating circumstances (IE, part of the cloud being caught in a jetstream). Even at Chernobyl (which was WAY worse that what happened in Japan) you don't have to get very far away from the site of the accident before everything is ~normal again.