[quote=Dinh AaronMk]
An argument could be made that over two-hundred years would be enough time for at least the hardier trees to come back. Most of the very deadly radiation tends to decay rather quickly.
[/quote]

Nuclear defense is pretty tricky, but in less ways than you'd expect. The intense shit gets washed out by the rain within the first couple of weeks, and you can hang out outside in your MOPP suits after that happens and start like, pressurewashing the ground to get everything else out. I don't remember an exact procedure, but I can research.

Fallout is just radioactive particles in the dirt. Once you clear that away there's not too much of a problem. Probably can't plant food and stuff, but you can walk around. Hell, most of Chernobyl right now is able to be hung out in, and has been for a while. That's our case study.