So far few answers talk about nuclear detonation device and even someone state to not even worry about such thing as the Faraday cage. But is a nuclear detonation the only scenario, is it? What about three mile island or Chernobyl? What about a solar flare enough strong to fry all satellites and electronics in a vast area of the planet? or a neutron bomb that detonates at the stratosphere? I am convinced that even is you are far enough from the destruction radius of a five megaton detonation, under very special circumstances, your possibilities to survive are slim but will increase by a factor of the understanding and preparedness against such event. Otherwise, the governments of the nations that hold nuclear arsenals would not spend in their survival of top leaders and would be resigned to "hope" the "others" would not detonate their bombs. This is a topic to discuss at all levels, to spend immense amounts of time, search, study and money. Some would say it is unnecessary, it is no chance to survive. That negative attitude is unwise and will cause more damage.