Radioactivity : 80 years after nuclear war

[ArlEammon]

I'm doing a RP where it's 400 years after nuclear war destroys civilization. My question is, what about 80 years after the fallout? How radioactive would the world be?

Like, specifically the ground zero zones, and then several miles away from ground zero, how much would the radioactivity have diminished?

[Jallorn]

The half-life of U-235 is 700 million years, while that of Pu-239 is 24,000 years So it depends. It depends on the material the nukes used, how high up they were detonated (most of the radioactive particulates from the bombs at Hiroshima and Nagasaki appears to have been disseminated into the atmosphere, rather than staying clustered at the bomb sites.) and other factors I'm sure I'm not knowledgeable enough to identify.

That's not incredibly useful, but I only did some very brief research, so with a bit more, you may find more, but this seemed enough to give you a direction to think on.

[Jay R]

I'm doing a RP where it's 400 years after nuclear war destroys civilization. My question is, what about 80 years after the fallout? How radioactive would the world be?

Like, specifically the ground zero zones, and then several miles away from ground zero, how much would the radioactivity have diminished?

That depends so much on the type, size, and quantity of the bombs, that you can pretty much make your own decisions to fit the world you want to build.

[ArlEammon]

That depends so much on the type, size, and quantity of the bombs, that you can pretty much make your own decisions to fit the world you want to build.

That makes sense. With 2018's bombs, I wonder what life would be like in 2100.

[Ramza00]

There are bombs that are more radioactive in the short term (producing in the short term more killer radiation), and there are bombs that are less radioactive than this but the radiation last longer due to longer half lifes....

But this type of bomb is perhaps one of the scariest types due to the "sweet spot" of making life uninhabitable for decades in a place with enough contamination in an area.

https://en.wikipedia.org/wiki/Cobalt_bomb

[factotum]

The half-life of U-235 is 700 million years, while that of Pu-239 is 24,000 years So it depends. It depends on the material the nukes used, how high up they were detonated (most of the radioactive particulates from the bombs at Hiroshima and Nagasaki appears to have been disseminated into the atmosphere, rather than staying clustered at the bomb sites.) and other factors I'm sure I'm not knowledgeable enough to identify.

I'm pretty sure that most of the radioactive fallout that comes from an atomic explosion isn't actually from the radioactive material in the bomb itself--a critical mass of U-235 is only 52kg, after all, and plutonium is even smaller. Most radioactive fallout is created in the explosion by neutron activation (e.g. regular non-radioactive atoms absorb one or more neutrons and get converted into unstable elements). So, you can't base how long the fallout will hang around on the half-lives of the bomb materials.

[Yora]

That makes sense. With 2018's bombs, I wonder what life would be like in 2100.

Again, it depends on how many and where. One of them wouldn't make much of a difference beyond the immediate impact area. All of them very much would.

You need to work out your nuclear war scenario first. Where three or four bombs used, or did the sides try to wipe each other out with everything they had? Or anything in the middle between them?

[gomipile]

Also, by the nature of nuclear physics, the most dangerous isotopes are the ones with the shortest half-lives. It takes much larger quantities of longer half-life isotopes to pose a danger.

[Anymage]

Again, it depends on how many and where. One of them wouldn't make much of a difference beyond the immediate impact area. All of them very much would.

You need to work out your nuclear war scenario first. Where three or four bombs used, or did the sides try to wipe each other out with everything they had? Or anything in the middle between them?

Or conversely, since this is in service to a game setting, knowing what setting elements OP wants can help us figure out what doomsday scenario could help bring that about.

[HandofShadows]

As others have said there are huge number of variables.

The size of the bombs and were they set off has a huge amount of influence of fallout. Small bombs make less fallout than the big ones. If the weapons are airburst (10,000 feet off the ground) these will a lot less radiation on the ground in that area compared to if it went off at ground level. Setting nukes off at ground level creates a lot more fallout since the detonation is kicking tons (litteraly) of radioactive material up into the air. Also the site of the detonation will be radioactive. One last thing to consider is how the bomb was bhuilt. Some nukes are dirtier than others in both the type of radiation produced and how long it lasts.

Setting off a neutron bomb is going to produce a less long term radiation than a lot of bombs (of course the short term radiation is going to be horrific). One last thing to consider is if the nuke was deliberatly "salted" to produce more and longer lasting radiation (A cobalt bomb). If one of those was set off, even 50 years later people could get a lethal dose of radiation in just a few days.

[ArlEammon]

Or conversely, since this is in service to a game setting, knowing what setting elements OP wants can help us figure out what doomsday scenario could help bring that about.

Basically, the main setting the PCs play in is in 2425 AD. However, there's a special time period of 2100 AD where two major players begin to fight each other by setting their heroes and villains against each other. I don't know how likely it is there could be much confrontation between each other, and what the world would be like.

[Jay R]

Basically, the main setting the PCs play in is in 2425 AD. However, there's a special time period of 2100 AD where two major players begin to fight each other by setting their heroes and villains against each other. I don't know how likely it is there could be much confrontation between each other, and what the world would be like.

OK. Getting back to my suggestion to make your own decisions to fit the world you want to build, I recommend that there is enough radiation to prevent an all-out war in 2100, but not enough to prevent minor raids.

And the good stuff you want them to find in 2425 is covered in too much radiation in 2100.

[wumpus]

It has been 72 years since the last nuclear war, I don't think either Hiroshima nor Nagasaki is particularly radioactive. Animals have been doing well in the Chernobyl exclusion zone for some time (doesn't mean I want to spend a human lifetime there).

As a rule, radioactivity simply means the rate at which an atom will release energy, which in turn typically depends on how likely the the atom is going to fall apart at any one time. So highly radioactive fallout decays quickly, the stuff that takes a long time to decay rarely releases all that much radiation.

Of course this is just a general rule. Using cobalt bombs pretty much means that it might be uninhabitable after 80 years (I doubt that anyone admits to the existence of specific cobalt bombs and how long they will poison the land). Another huge issue is if the radioactive isotope forms a molecule that stays in a human body: being around uranium is one thing, carrying around radiation in your body is quite another.

To be honest, I'd suspect the chemical damage would be much worse. Nuclear war would simply break the infrastructure so badly that pretty much every failsafe wouldn't be enough, every hazardous material would leak, and zero retaining equipment would retain (few things are designed to last 80 years without maintenance). Petrochemicals are the obvious "nasty chemicals used in huge quantities", but you can at least expect post-apolcolyptic people to work very hard to use it all up (or at least collect and horde).

[ArlEammon]

It has been 72 years since the last nuclear war, I don't think either Hiroshima nor Nagasaki is particularly radioactive. Animals have been doing well in the Chernobyl exclusion zone for some time (doesn't mean I want to spend a human lifetime there).

As a rule, radioactivity simply means the rate at which an atom will release energy, which in turn typically depends on how likely the the atom is going to fall apart at any one time. So highly radioactive fallout decays quickly, the stuff that takes a long time to decay rarely releases all that much radiation.

Of course this is just a general rule. Using cobalt bombs pretty much means that it might be uninhabitable after 80 years (I doubt that anyone admits to the existence of specific cobalt bombs and how long they will poison the land). Another huge issue is if the radioactive isotope forms a molecule that stays in a human body: being around uranium is one thing, carrying around radiation in your body is quite another.

To be honest, I'd suspect the chemical damage would be much worse. Nuclear war would simply break the infrastructure so badly that pretty much every failsafe wouldn't be enough, every hazardous material would leak, and zero retaining equipment would retain (few things are designed to last 80 years without maintenance). Petrochemicals are the obvious "nasty chemicals used in huge quantities", but you can at least expect post-apolcolyptic people to work very hard to use it all up (or at least collect and horde).

Hmmm then maybe advancing that important date by another 25 years would work out, the wiki says that at 105 years were looking at an almost normal area where the only noticeable difference was a small rise in cancer.

[Khedrac]

Animals have been doing well in the Chernobyl exclusion zone for some time (doesn't mean I want to spend a human lifetime there).

This statement is actually surprisingly debatable. Animals look to be doing well because there are no humans to hunt them or otherwise accidentally kill them. That doesn't mean that their life expectancy is what it would be without the radiation.

There was one episode of River Monsters where Jeremy Wade was looking for a fish (basically the local Wells Catfish) and got permission to fish in the exlcusion zone because the scientists studying the animals in the area has no fish samples.
The fish he caught when examined turned out to be half normal size for its age and riddled with cancer.

So, for animals a radioactive wasteland is actually better than most human inhabited territories...

[Lazymancer]

I'm doing a RP where it's 400 years after nuclear war destroys civilization. My question is, what about 80 years after the fallout? How radioactive would the world be?

Like, specifically the ground zero zones, and then several miles away from ground zero, how much would the radioactivity have diminished?

Depends on the nukes, but 80 years down the line - you can safely assume that most of the world will be non-radioactive (which does not rule out problems with ecology/climate - or toxic chemicals). Living on a ground zero might still be unhealthy, but not deadly. Especially, if you walk through, without trying to take a nap or otherwise hug a source of radiation.

One last thing to consider is if the nuke was deliberatly "salted" to produce more and longer lasting radiation (A cobalt bomb). If one of those was set off, even 50 years later people could get a lethal dose of radiation in just a few days.

Depends on the amount of radioactive materials. Realistically speaking, fallout will be sufficiently dispersed so as no to matter much.

Also, I'm not aware of anyone actually trying to build cobalt bombs.

[Grey_Wolf_c]

This statement is actually surprisingly debatable. Animals look to be doing well because there are no humans to hunt them or otherwise accidentally kill them. That doesn't mean that their life expectancy is what it would be without the radiation.

About the same, but only because animals hardly ever die of old age. Cancers, even those caused by long-term radiation exposure, are old age diseases. Terrible for humans, who no longer fear dying of, say, cholera at 30, but irrelevant to deer, who get eaten by wolves the moment they start slowing down with age.

I am sure there are some animals in Chernobyl which die of a cancer they would not have had in other circumstances, but yes, any shortening of their life expectancy is more than compensated by the lack of the single factor that kills more animals than any other factor in the world by a large margin: humans.

Grey Wolf

[Bohandas]

IIRC the fallout from a cobalt bomb would only remain dangerous for a few decades and that's the worst kind for fallout

[Lazymancer]

IIRC the fallout from a cobalt bomb would only remain dangerous for a few decades and that's the worst kind for fallout

Radioactivity decrease is relative, not absolute. If it's cobalt bomb, radiation will be halved every ~5 years (half-life period), until it reaches safe range - but will never be fully "gone".

Consequently, you can have "non-dangerous" fallout since the day 1, or dangerous zone that will last for centuries. Depends on the amount of radioactive materials you've got.

[ArlEammon]

Radioactivity decrease is relative, not absolute. If it's cobalt bomb, radiation will be halved every ~5 years (half-life period), until it reaches safe range - but will never be fully "gone".

Consequently, you can have "non-dangerous" fallout since the day 1, or dangerous zone that will last for centuries. Depends on the amount of radioactive materials you've got.

Then I guess the question is how fast will the fallout decay using the materials we have today in 2018.

[Dodom]

This statement is actually surprisingly debatable. Animals look to be doing well because there are no humans to hunt them or otherwise accidentally kill them. That doesn't mean that their life expectancy is what it would be without the radiation.

There was one episode of River Monsters where Jeremy Wade was looking for a fish (basically the local Wells Catfish) and got permission to fish in the exlcusion zone because the scientists studying the animals in the area has no fish samples.
The fish he caught when examined turned out to be half normal size for its age and riddled with cancer.

So, for animals a radioactive wasteland is actually better than most human inhabited territories...

Adaptability to ionising radiation seems to vary by species. Birds seem to be very tolerant of radiation, unless they're red. It appears that the precursors spent to form pheomelanin are needed to neutralise the free radicals caused by radiation, and an animal with a lot of red pigment might not have enough left to protect their DNA.
http://onlinelibrary.wiley.com/doi/1...12283/abstract
I don't know if there's any data on other animals, by example would a human brunette fare better than a redhead, but one conclusion we can safely draw from it is that not all animals are equally harmed, and we can expect to find a different ecological balance than in a healthier environment.

[Lazymancer]

... today in 2018.

Would you mind telling me what lottery numbers had won recently?

[Lvl 2 Expert]

Would you mind telling me what lottery numbers had won recently?

Or maybe just the current price of a few volatile alt-coins?

[halfeye]

I'm doing a RP where it's 400 years after nuclear war destroys civilization. My question is, what about 80 years after the fallout? How radioactive would the world be?

Like, specifically the ground zero zones, and then several miles away from ground zero, how much would the radioactivity have diminished?

From Wikipedia:

The Seven Ten Rule

The danger of radiation from fallout also decreases with time, as radioactivity decays exponentially with time, such that for each factor of seven increase in time, the radiation is reduced by a factor of ten. For example, after 7 hours, the average dose rate is reduced by a factor of ten; after 49 hours, it is reduced by a further factor of ten (to 1/100th); after two weeks the radiation from the fallout will have reduced by a factor of 1000 compared the initial level; and after 14 weeks the average dose rate will have reduced to 1/10,000th of the initial level.[23]

https://en.wikipedia.org/wiki/Nuclear_fallout

Thats taking into account the fact that one source of radioactivity may decay into another. As people said, how much you get where is variable, but that rate of decline is standard.

[Spore]

I think this was pretty well - and vague - discussed with Fallout's bombs. Short version is: Modern "tactical" nukes are used for the explosion not the radiating effect. The land would still be irradiated but not for long. Of course some diseases would prevail but all in all, extremely irradiated zones are rare - besides the occasional atomic power plant that would leave small zones to be heavily irradiated. Fallout's bombs were more sinister. They are designed to "salt the earth" to make large areas uninhabitable. Which is of course against any logic dictated by warfare because you attack terrain to capture it.

Only really deranged minds would construct bombs made to irradiate the world for several centuries. Then again, humanity is not of sound mind most of the time anyhow.

[Lazymancer]

Fallout's bombs were more sinister. They are designed to "salt the earth" to make large areas uninhabitable. Which is of course against any logic dictated by warfare because you attack terrain to capture it.

Only really deranged minds would construct bombs made to irradiate the world for several centuries. Then again, humanity is not of sound mind most of the time anyhow.

Unless we are using Fallout physics, irradiating the world for several centuries requires insane amount of radioactive materials. IIRC we can only irradiate England for a century.

Half-life of 5 years (the "salted" Cobalt) means that a century later we'll be having one millionth of the initial radiation.

[Storm_Of_Snow]

Another thing to consider is what the radioactive decay products are - high energy (gamma and x-ray) is probably not a good idea, but alpha and beta could well be livable with appropriate handling (thick clothing, radiation reducing drugs, breathing masks and purifying water before drinking, growing food in sealed environments with decontaminated ground, airlocks and decontamination facilities at residential building entrances and so on). The real limit is how much information and knowledge survived both the initial conflict, and the intervening years.

And then there's weather effects - wind will blow radioactive dust from the detonation site, while rain will wash contaminants into ground water and water courses, a prolonged nuclear winter could lock radioactive contamination away in ice, rendering it less dangerous (unless you melt and drink it).