According to Ronnie Reagan (RIP) America has Star Wars anti-nuke protection from satellites in geo-sync orbit over the US.
More on that via this link.
https://encrypted.google.com/#q=anti+nuclear+satellite&*
There is more than one kind of nuke explosion - the most deadly is the sky burst - this is a nuke bomb detonated high over a city the blast from which then kills most of the people in that city leaving much of the structure intact - so it is believed.
Nuke bomb film US & Russian
https://www.youtube.com/results?search_query=nuclear+bomb+test+film+ground+level
Survivors in a nuke attack - cities such as London and New York have vast underground networks - Subway in NYC and the Tube here in London. At any one time, many thousands of citizens of both cities will be travelling underground - they will likely survive but only by staying underground.
There is another group of would be nuke war survivors in the USA - these are folk who have built their own nuke bomb shelters either under their houses, deep below their house yards, or else got Government land and built a bunker there.
Nuke Bunkers
https://www.youtube.com/results?search_query=private+nuclear+bunkers+usa
A lot depends on a person s age. I m 76 and if there is a nuke bang over London, my plan is to go outside and get the final sun-tan and just die. Younger folk may want to do something about their survival such as moving away from large cities or, if affordable, building a nuke bunker.
But worry not. There is not going to be a Nuke war. What is happening right now is a collaborative effort by USA, NATO and Russia/China to defeat ISIS - we must kill these jihadists before they infiltrate their way into our homelands where they will create more death and destruction.
I read on one of the online UK Newspapers this morning that the surviving remains of the Hanging Gardens of Babylon have been found underground - God save that from ISIS who will simply destroy it, as they have done to so many other Classical remains of the Greco-Romano era.
Stay Safe