Re: Fallout @bearbonez
I think pretty much everyone now agrees that above ground testing is bad, and being close to a ginormous radiation source like an atomic bomb increases your chance of getting cancer. Then again, so does smoking, asbestos, certain industrial chemicals, and so forth.
And the truth about fallout: within a short period of time, nearly all of it decays into low-level or non-radioactive materials. A few things like Co-60 hang around for longer, but they all end up being washed away by rain, blown away by wind, and diluted to statistically "un-detectable" levels. At that point, they don't do squat.
In a localized area, fission products from 50 lbs (or so) of uranium is pretty nasty. evenly distributed around the world, not so much. Thermonuclear devices would create a lot more material as neutron-activated "whatever used to be where the crater now is". But that's likely to be short-lived as well, except for things like Co-60 [which would be formed from Fe-59 + neutron]. Fortunately that, too, will eventually be washed or blown away, to levels "significantly below background".
/me points out that radioactive material is naturally occuring, including "natural reactors" formed by naturally occurring Uranium and other fissionable materials. The sun is the #1 radiation source on the planet, and you'll get more additional exposure flying during the day at 20k feet than from any amount of fallout remaining from cold war nuclear tests. Or Chernobyl. Or Fukushima. (unless you go there and directly expose yourself, but that would be kinda dumb)