Wired has a wiki up about how to live through a nuclear blast. Some representative advice:
The seconds following the initial flash are critical. Luckily, factors like explosive yield, weather, and distance can lessen the effects of the shock wave — but don’t kid yourself, it’s coming. The best method for weathering this stage is finding an ideal barrier between yourself and the combination of extreme pressure, heat, thermal radiation and 500mph winds headed your way. This is where survival gets a little tricky.
Hopefully this one develops nicely. I am become death, destroyer of worlds! Image: Robert Longo, from his stunning series of ginormous charcoal drawings of atom-bomb blasts.







