You know, I've wondered about that for a while... According to [url=http://www.oism.org/nwss/s73p912.htm]this[/url], it really wouldn't take all that long at all for radiation/fallout levels to drop into manageable ranges (especially in the radiation-obsessed Fallout universe, with its ubiquitous Rad-X and Rad-Away).

Still, though, we're talking about a place based primarily on what Americans in the Fifties thought the future would be like, so obviously radiation works very differently there... And I'm pretty sure most of the survivors of the Great War either became ghouls or were in Vaults and bunkers and such... Yeah, I really don't know how the human PCs are going to be able to do anything out there, at least not for a few years (decades).