Depends on a lot of factors. Yield. Terrain. Weather. Height of detonation. There's no "one size fits all", a little tactical bomb might have a cicle of total detruction limited to a few blocks - with lesser damage further away, radiation spread determined by weather. A multi megatonne bomb can wipe out an entire city.
Do we know who has the biggest baddest ones and who has the smallest ones? So many variables. Thank you for your reply Sbf! I hope all of this info is moot conjecture and just for conversation. I hope we don't have to live any of it. Well, die in it actually. :(
Slartibartfast 