As a person whose career is dedicated to mitigating risks, this is an excellent article about what should occur if a terrorist or rogue nation ever detonates a nuclear device in the U.S. The author is correct that it is not a 20 megaton hydrogen bomb (think Dr. Strangelove) blast we should fear (for which there is little we can do to save our lives) but rather a blast smaller than Hiroshima. We can do a lot to save our lives should the latter occur.
The advice to have a full three day (minimum) supply of food, first aid supplies, etc., is excellent for storms, terrorism, hurricanes, or earthquakes. Kathleen and I follow it and I suggest you do, too.
There is a movie trailer playing on TV where one of the characters says, “just because you choose not to believe in the devil does not protect you from him.” Regardless of it being “unthinkable,” there are likely evil people wanting or even planning such an event. Proactive is always better than merely hoping for the best.