Most people underestimate the survivability of nuclear war.
It is important to consider that, while their are many nuclear weapons in the world, most analysts of the subject of nuclear exchanges conclude that most weapons would not make it to their targets (or function).
More than half would be among the weapons that would:
- Be destroyed by pre-emptive strikes on their launch site/platform
- Malfunction
- Be held in reserve for later exchanges....that never come
- Be intercepted en-route to their target
- Miss by a large distance
That last point is interesting.....in that, even when people are located far from any likely target, there exists the possibility of being hit by a "miss".......but at very much lower probability than being hit when you are adjacent to a high priority target.
The two most well proven data sets we have regarding casualties are from Hiroshima and Nagasaki......with bomb yields of 15kT and 20kT respectively.
Here is a good reference that goes through the casualties at those bomb sites.
https://thebulletin.org/2020/08/counting-the-dead-at-hiroshima-and-nagasaki/
from that paper:
View attachment 154682
So, the maximum distance that people were killed at, from ground zero, was about 1.5 miles........for a 15kT weapon. At 3 miles, it didn't injure many.......
Another good resource for assessing/considering survivability is this site:
https://nuclearsecrecy.com/nukemap/
on that site, you can drag the cursor onto your nearest target, set the yield (I would use 500kT) and either ground or air burst the weapon for the simulation. Most cities would be targeted for air burst, while buried infrastructure like Cheyenne Mountain or missile silos are probably targeted for ground burst.
You can also enter the prevailing wind direction/speed for your area, to model the fallout applicable only to ground burst detonations.
Most people who do the above, will find their survivability is better than they would have guessed.
If you find that you are located somewhere at very high risk, then you should develop plans to be somewhere else if the probability of a nuclear exchange gets very much elevated.
Surviving a nuclear war is just like surviving any other very severe crisis.
Consider how to best do that with a calm, logical, well informed and un-emotional mindset.
Quitters never win and winners never quit.
Reality? I don't know, it's a novel. 
