Your normally fine if your outside 4 miles of the blast site. Upto 15 miles is aftershock whereby your insides will smash against bone, organs and flesh causing horrific pain if you don’t die instantly. But it all depends on the size of the initial explosion. Then you have radiation fallout to worry about. Drops by 50% after 24 hours, 75% after 36 hours and 85% after 48 hours. That’s assuming no further detonations.
If you manage to survive after the first 7 days and know how to filter water and food plus have a warm safe place then your chances of survival increase to around 80%.
But if your close to a military, naval, air base or energy infrastructure then your basically fcuked.
Even if you are lucky enough to survive the first 7 days you will find yourself having to kill your own people as everyone will be looking for warmth, food, shelter and water.
Back in the 1940s when they dropped the Hydrogen bombs on Japan, records indicate that many were killed by someone they knew, be it, family or friends.
Most people don’t realise what another fellow human being is prepared to do to say alive.