Well real life places like Hiroshima are doing fine after 60 years. Besides radiation does work like it does in real life, Vault City was exposed to radioactive particles because the ground water had been contaminated from a nearby Nuclear plant, they didn't turn into Ghouls or grow six stories, they all experienced chromosal damage and fertility issues along with others which they were fully able to classify.
Even comparing it in-game, the White House is a crater and a building on the otherside of the road is perfectly fine so unless your going to tell me that explosions work differently in the Fallout Universe then find me a rational explaination for what I feel is Bethesda's error.
( I can respect that, and i can agree that the Radiation itself works like in Real life, but, Vault City was being effected by a leaky Nuclear Reactor, not a Nuclear Warhead, so i feel the first part, while a very valid argument, and i agree because the affects would be similar, is invalid to the discussion. As for the rest, as i said, those are missing realistic factors Bethesda felt IMHO that were not crucial to the game, and i do not think those real world factors were all that important, as the war was 200 years ago, unless your trying to figure the Megaton Explosion, of which i can understand, as that felt more like a Kiloton explosion, and would be consistent with the US Arsenal of the Early 50's, as the damage range was not to far because of the crater, and the Radiation count did not go out farther than the gate of Megaton. So if you want to attribute the lack of realism to Bethesda, ok, but the games was not designed for realism on a major scale, otherwise it would be more like the real world.)