User blog comment:Mr.Xeight/Forum for the Federation of Greece in the Universe of 1983:Doomsday/@comment-2076280-20100823175149

Travel and decontamination efforts are only safe with special equipment, which most people wouldn't have. Also, the main example we have are the Hiroshima and Nagasaki bombings, which were relatively small bombs. The much larger bombs that would have been dropped in this scenario, such as the 10 megaton bombs both the Soviet Union and USA had, would caused the radiation to linger for much longer. Plus, the blast would alter the landscape, destroy all signs of civilization, and kill everyone there. After the survivors fled, it's doubtful they would return unless a large-scale rebuilding effort took place.