User blog comment:Mr.Xeight/Forum for the Federation of Greece in the Universe of 1983:Doomsday/@comment-1593341-20100823165057

I think people over-estimate the effects of fallout. Admittedly my source is wikipedia, but 2 weeks following the blast radiation has subsided enough to make travel and decontamination efforts safe. I don't see why it would take 20 years to become inhabitable.