The closest Hiroshima survivor was in a cellar only 300 m from ground zero -- which is very close when you consider that the bomb was detonated at 500 m altitude.
Now the device North Korea tested back in September was 10x to 20x more powerful than the Hiroshima bomb, but still if a bomb were detonated over Pearl Harbor and you were standing on the beach in Waikiki, you'd almost certainly survive, albeit possibly with thermal burns.
Here's the thing about all that Duck and Cover stuff from the 50s: when you're talking about a handful of bombs distributed over the entire country, diving under a picnic blanket actually makes sense. It wont' help you if you're at ground zero, but if you're five miles away or so it could make the difference between surviving uninjured or requiring hospital treatment. Multiply that by tens of thousands of people, and duck and cover type education is a sensible defensive strategy.
There is, however, a simple counter: attack with a lot more warheads. By the early 70s the Soviets had something like 25,000 of them. An all-out attack would not only result in multiple bombs falling on every city, it would guarantee the collapse of American society and a short and hellish existence for anyone unlucky enough to survive. Fatalism makes sense in that scenario. You might as well enjoy the show for a few hundred milliseconds and then die.
That's not where we are with a North Korean nuclear attack, not by a long shot. North Korea's arsenal is not large enough yet to cause the collapse of American society, or even to kill the majority of people in a city like Honolulu. So maybe we should be dusting off those old civil defense films.