They taught us in the Military that there are 5 stages after an Nuclear Event
Stage 1.) Immediate Blast
Well, Nuclear Blast is also a bomb, which will creat heat shock wave and an Explosion. People with the Immeidiate Blast area will be the victim of the Blast and depend on the height of the detonation and also the Shielding effect, victim may or may not disintegrated in the Blast. But if you do, that would be the best way to go as the blast will centered about 3000 degree Heat and even your ash will vaporise, so it left nothing but scortched earth. Death, if occur is instantious
If you do not die in the blast. Then you will headed Straight to Stage 2
Stage 2.) Fall out and Acute Radiation Sickness (ARS)
Fall out is the remaining Fission material left in the atmospohere. Which according to the type of fission material and the amount of it, It will stay in the Atmosphere which got bought up by the concussion from the explosion.
The term fall out is literally mean the stuff (radiation) that falls out fro mthe sky
Fall out can be carry thru win and carry thru rain. Wind will spread the fall out in different direction while rain will drop the fall out into the earth. And which affect human life.
Fall out can be particular nasty as it not only affect human but it also affect the environment, with modern pumbling, rain fall from the sky and into reservoir and into our water table reegion. If Fall out presented in rain, it wil lrender our drinking water undrinkable as radioactive material will survive in water for the duration of their half life and remain
So bascially what fall out can do is to cause acute radiation sickness and you may died as a result of it. ARS is the most nasty way to do and if you don't die from the ARS, you will suffer even more that you wise you died from ARS and then you wish you died in the blast.
Depending on the dosage one get, it may or may not cuase death both immeidately or eventually, Lethal dosage is 5-10Gy and everything below that you may still die of complication. Ie depend on treatment of symdrom.
There are a few effect on Radiation Sickness and from mild to severe contemination. You will suffer from Nausea and vomit, then progress to Diarrhea, fever and finally your central nervous system broken down and you die
How fall out kill you are simple dea, imagine your body are a one big microwave and your organ is the meat you want to cook. When you inhale ingest radioactive material, you are inhaling a great dose of microwave, with that inside your body, it is the same as you turn on the microwave and cook your organ from the inside. Then your organ wil lfail one by one and eventually death is the final product, not before you suffer for at least 48 hours of the symptom i mentioned before. And that is the best case senario.
Worse case senario is, you survive the ARS stage and move on to Chronic Radiation Sickness stage, which mean you can still die and suffer from long term diease like cancer and trauma and Retiring of Brain function
Given you survived Stage 2, you move Directly to stage 3
Stage 3.) Survival on a Contaminated World
With fall out everywhere, even for a little dose which will not kill you outright. Fall out can be accumlated and absorbed in anything, even human body. But mostly in metal surfaces.
While every food source in the contaminated region are uneditable (Either fall out contaminated the meat directly or if in a can, the metal.) and all water on the region is not drinkable. How do you survive a world without food and water available is a critical question. If you are in a fall out affect region, you cannot even grow stuff from soil as the soil itself are also contaminated. The only way is to get what you have and leave. But do remember not only you have this sense also eveyone who survived the blast and fall out will think of this. Hence a mess migration trial is what's followed.
If you can survive in a world without readily available food and water, then you can move on to the next stage.
4.) EMP
EMP is a burst of energy which fried all thigns with electronic, rendering them useless. All item, except for simple sircuitry would not survive. That's mean, Cars, Computers, Rice Cooker, Electric Stove, Lighting, Machinery and all other electronics.
Without the modern machinery, you need to work extra hard to do normal stuff that you would do in just minutes or even second.
Some people can survive a world without any electronic, some can't, if you can, move on to next stage and the final stage
5.) Nuclear Winter
Nuclear Winter is an climate effect on the earth when large cloud of dust and debris settle in our inner atmosphere Which blocking the sunlight as well as increase the CO2 content on our ozone layer.
Basically, climate shift from summer to winter and winter to extreme cold as the sunlight factor which keeping us warm decreased and the CO2 in theatmosphere form a protector screen that prevent more UV and Ironically Radiation from the sun to heat up the earth and thus entering a extreme cold sitaution
Scientist estimate that a 20 degree C different could be resulting from a Nuclear winter, so a place with 30C in the summer will drop to 10 degree in the summer, and a place with 10C in the winter will drop to -10C in the winter.
It would still be ok if you have an intact shelter but with electricity and electronic gone as per the EMP, you probably cannot survive a nuclear winter without heater of any sort.
However, good news is, only enough soot and debris can trigger nuclear winter. Meaning if the damage done by the blast is not severe, chances are nuclear winter will not happen in any case.
Interesting Fact regarding Radiation and Nuclear Explosion
fact 1. Nuclear explosion run on a formula destruction increase will result in damage of radiation decrease.
The height of the detonation determine the damage level from the fall out and destruction level of the blast. If the bomb detonate closer to earth, Blast damage is maximum but fall out release will be minimum. With High Alt Detonation, Blast damage is mimimum but the fall out release is maximum.
That is because the blast took on a factor of LOS to release radiation wave. With the lower the altitude, the more factor obstruct the LOS and hence blocking the Radiation and it only affect locally. However, if the det is an airburst, with virtually unlimited LOS, fall out could be expaned anywhere and everywhere.
So the bigger the bang, the less effect it have in a nuclear explosion.
Fact 2.) It is safe to be outisde if Fallout not continue to deposit While still emitting Radiation
Human body "Digest" radioactivities over time. Acutally we all subject to radiation one way or another, as long as the dosage is not over the lethal dosage, human body can take it. So it's safe to travel a short period of time if There are still radioactivities on the ground. That does not equal to extended explosure is safe.
Fact 3.) Everything count if you are building on radiation barrier
Everything (Except metal, of course) can be used to create a barrier. Research done by DOE some years ago show even basic manchester fro ma bedding can provide a good protect from radioactivities. It's would be better you are cover by something, then nothing at all. It maybe is that a few protection and a few second of choice that save your life.