Up to a few hundred feet forA bombs
Up to a few miles for big H bombs
Essentially No chance of Survival
Thermal Radiation & Blast: Zone 2
2000 to 10000 feet -- A bomb
10 to 25 miles -- big H bomb
Survival is possible; your chances are
better at larger distances from ground zero.
Radioactive Fallout: Zone 3
Up to hundreds of miles downwind.
Survival chances are excellent if you are prepared and know what to do.
Anvil Top of Mushroom Cloud
The Critical Zones of a Nuclear Detonation