U.S. Called Unprepared For Nuclear Terrorism
I loved the example from the government's site: if a nuclear weapon is detonating a block away, go around the corner. Well, I guess that advice can't hurt; it won't make anyone more dead than they would be if they just stood still and waved. Perhaps it was meant to be advice for a truck bomb surrounded by radioactive material?
The advice on what to when you are (most unfortunately) downwind of a somewhat distant mushroom cloud was more interesting. Determine wind direction and run (carrying the children?) somewhere between perpendicular to the wind and downwind. I suspect the best choice might depend on what direction was easiest to travel in. The presumption is one will be afoot since roads will be blocked by crashed vehicles. A bicycle might help, but it might also expose one to opportunistic assault. Going underground is not considered particularly helpful.
I can see why the Feds prefer not to deal with public education in this domain. To admit such things are thinkable is to open a discussion that the Bush administration prefers to avoid.