BACKSTORY: So in my story there was a type of nuclear winter that forced surviving humans to live underground until the world above became breathable again. By now the world than once was (our world) is gone and nature has taken back the world. It takes them a few centuries but a form of civilisation builds again. Technology is long forgotten and the world than stands is a modern take on vikings and incorporates cultures from all over the world/throughout history.

My question is, in a world without technology, these left over pockets of radiation are seen as poison. What methods would be possible for detecting or getting rid of this ‘Poseidon’?

My ideas for detecting it so far mainly is the use of certain animals beings able to sense in and not going near these areas, including birds flying around or away from it.

I want pockets of wastelands within the world where these poisons are, but they need to be able to travel through them.

Thanks for any help in advance.

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    $\begingroup$ You don't mean "Poseidon" do you, unless that's the name you're culture is using for it, in which case fair enough. Autoconnect has a lot to answer for. We invite you to take our tour and, when you need guidance regarding our ways, consult our help center. Welcome to worldbuilding. $\endgroup$ Mar 7, 2021 at 2:38
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    $\begingroup$ At that level of technology, the only real radiation sensing device that might be plausible is a en.wikipedia.org/wiki/Spinthariscope, which is zinc sulfide in a dark container so that you can see flashes from radiation interacting with the ZnS. It's not exactly fast or convenient though. $\endgroup$ Mar 7, 2021 at 4:14
  • $\begingroup$ Cloud chamber ;D $\endgroup$
    – user6760
    Mar 7, 2021 at 6:58
  • $\begingroup$ I'd ask a separate question about how you could possible arrange for these long-lived areas of radioactivity to persist. They can't be fallout... even stuff from a long-lived salted bomb blast would have been washed away and absorbed or sunk or whatever after a few centuries. $\endgroup$ Mar 7, 2021 at 9:42
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    $\begingroup$ You might be interested in the "atomic gardens" which were used to test the effects of radiation on plants, and to develop new plant varieties: ps://en.wikipedia.org/wiki/Atomic_gardening $\endgroup$
    – jamesqf
    Mar 7, 2021 at 17:15

5 Answers 5


Only a few things will be deadly radioactive after centuries, and they'll be naturally buried for you.

Let's split the radiation into two categories: near-instant death, and bad for your health long term.

In the instant death category; You only need to worry about very high grade things this far in the future: Bomb parts, reactor core parts, high level nuclear waste, fractured nuclear fuel rods, etc. These will be exceptionally rare, and these pieces of debris will be buried by rubble, dirt, or washed into the oceans by centuries of nature doing its thing.

So long as you dont go digging, and dont pick up the strange shiny thing at the bottom of the water, you'll be fine.

When someone finds something pretty underground and everyone nearby mysteriously dies, someone needs to sacrifice themselves and throw it in water (even 1m of water will absorb 99%+ of the radiation).

Regarding the "bad for long term health": You wont be able to detect it, and it wont matter.

A few centuries after a nuclear war, ground zero will still be contaminated at a level you or I might consider notable, but a viking society where life expectancy is 40-50 years isnt going to make much difference.

The ground being instant death goes away after about 5 years, after wards every additional year slightly increases how long you can be exposed to it before you get deadly consequences. After 500 years radiation would be back to between background rates and "oh you might get cancer in your 50s" rates.

Not a big issue to those who consider 50 old age.

Real example:

This is the Chernobyl dead zone 33 years later - it's safe enough you can visit the outskirts in a tourbus: enter image description here

The absorbed dose of radiation in the exclusion area is between ~1.2 microsieverts per hour (10.5 millisieverts per year.) to 6 millisieverts per hour, depending on which tourist agency you visit, but this is expected to decay as the half-lifes of these products is measured in decades - Eg Caesium 137 halves every 30 years. After 210 years, it's 1/128th of the strength, so 6mSv becomes 40 microSieverts.

Chernobyl after 210 years would be 860 mSv per year. 270 years it'll be 215mSv. 100mSv in a year is the minimum value that has been shown to show an increase in cancer rates long term, but symptoms of (non-fatal) radiation poisoning won't appear at these levels.

enter image description here
By Randall Munroe - XKCD

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    $\begingroup$ Nice real-world example is wildlife thriving in the forest around Chernobyl! $\endgroup$
    – Sol
    Mar 7, 2021 at 4:14
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    $\begingroup$ Yes - And hiroshima city, and nagasaki city, and Los Vegas. $\endgroup$
    – Ash
    Mar 7, 2021 at 4:20
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    $\begingroup$ @John I didn't say its totally safe to go free-for-all in I said it's safe enough for guided tours on buses. I've seen tours go right up to the reactor building exterior (Hell even Grand tour on Prime did it in 2019). I've added the word "outskirts" to the tour description in case someone mistakes what I'm saying for "the danger zone is safe". $\endgroup$
    – Ash
    Mar 7, 2021 at 6:02
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    $\begingroup$ >where life expectancy is 40-50 years | Why does nobody get how life expectancy works?? No, Vikings didnt just die at 50. This number incluses the (back then quite significant) infant and child mortality. Once you made it past that you could epect to be 70 $\endgroup$
    – Hobbamok
    Mar 8, 2021 at 9:59
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    $\begingroup$ As others have mentioned, it's a myth that people "only lived until 50!" Infant mortality rate is awful by default, our birth canals are just barely big enough to push out an infant, it's so bad that our children are less developed than chimp babies when born, and babies heads are very squishy to compensate. Every single C section (that was not done out of the convenience of the doctor), every preeme, all of them would have died, possibly taking the mother along with them. Many statistics put infant mortality rate at over 20% in the 1800s USA, with childhood mortality hitting near 50%. $\endgroup$
    – Krupip
    Mar 8, 2021 at 20:12

You are dramatically overstating the long-term persistence of radiation due to nuclear weapons.

As an example, this is Ground Zero at Nagasaki: enter image description here

And here is the memorial at Hiroshima, about 500 meters from the precise ground zero: enter image description here

And here is an image of part of Bikini Atoll, one of the most nuked places on the planet. The roundish area of deeper water just above the forested island? That's the crater from the Castle Bravo test that accidentally went to a 15 megaton explosion and caused people to suffer radiation sickness due to fallout.

enter image description here

While the radiation levels of the atoll exceed safety margins, they are decreasing rapidly. The primary concern is caesium-137, which is still at levels considered hazardous, but the element has a half-life of 30 years. After 200 years, it will be down to about 1% if its initial levels, after 300 years 0.1%, after 400 years 0.01%, and after 500 years 0.001%, and so on, and that's purely out of decay and not the material being eroded and diluted, which decreases the effective exposure someone in that area would undergo.

So, essentially, with standard nuclear weapons after a few hundred years there's no practical immediate risk to life due to radiation. There will be no dead zones or poisonous wastelands.

  • $\begingroup$ Nitpick: that's not actually ground zero at Hiroshima, it's just where they put the memorial park. The real ground zero is next to a modern building, about 500 m away. If it wasn't for the plaque they put up, it would be exactly the same as any other street in a Japanese city. $\endgroup$
    – user71659
    Mar 9, 2021 at 5:28


Gamma-ray-sensitive flowers have apparently already been planted near many nuclear power plants.

A cloned species of spiderwort, a roadside wildflower, changes color from blue to pink when exposed to about the same radiation dosage as permitted by federal guidelines.

The flower has become popular with the antinuclear movement and is being planted by the thousands near nuclear plants worldwide.


Within a couple weeks of being exposed to radiation, the flowers mutate, and turn from violet blue to a bright pink.

-- Catcher In My Eye https://www.flickr.com/photos/heyitsdebv/5572073498

possibly referring to:

When radiation destroys the genetic material responsible for the dominant blue pigmentation of a stamen‐hair cell, the cell appears pink, according to Dr. Ichikawa. The number of pink cells counted is interpreted as a reflection of the amount of radiation damage. The color change can be observed most efficiently 12 to 13 days after the plant's exposure to radiation, the geneticist says. ... the plant also reacted to chemical pollutants ... The scientists hope eventually to be able to plant some around nuclear facilities in the United States.

-- "Flower is Detector of Slight Radiation" Bayard Webster. The New York Times, 1979 https://www.nytimes.com/1979/04/25/archives/flower-is-detector-of-slight-radiation-scientist-says-spiderwort.html

Native Americans used T. virginiana to treat a number of conditions, including stomachache. It was also used as a food source.[21] The cells of the stamen hairs of some Tradescantia are colored blue, but when exposed to sources of ionizing radiation such as gamma rays or pollutants like sulphur dioxide from industries, the cells mutate and change color to pink; they are one of the few tissues known to serve as an effective bioassay for ambient radiation levels.[7][21]

-- https://en.wikipedia.org/wiki/spider_wort

Gamma rays induced variations in seed germination, growth and phenotypic characteristics of Zinnia elegans var. Dreamland Smitha Hegde 2018 https://www.researchgate.net/figure/Effect-of-gamma-radiation-on-flower-colour-and-form-of-Zinnia-elegans-var-Dreamland-C_fig2_322244484

Isolation of flower color and shape mutations by gamma radiation of Chrysanthemum morifolium Ramat cv. Youka Tarek M. A. Soliman et. al. 2014. https://link.springer.com/article/10.1007/s10681-014-1127-z

  • $\begingroup$ The question is would they be an accurate signal of long-term radiation. If the gene is mutated and most of the plants have it, then they will reproduce to produce pink flowers long after the radiation is gone. As a result the flowers will only tell you where radiation once was, not where radiation is now. $\endgroup$ Mar 8, 2021 at 19:22
  • $\begingroup$ @user2352714: Yes, the Chrysanthemum article says that when genes are mutated in germ-line cells, they will reproduce to produce altered flowers long after the radiation is gone. However, the spider-wort articles imply that the gene is mutated in some of the stamen-hair cells, not in the germ-line cells, so after the radiation is gone, the plants will return to producing blue flowers. $\endgroup$
    – David Cary
    Mar 10, 2021 at 3:43

Detecting the dead zones is easy. They are dead. Despite the hope that every stray gamma ray will lead to a genetic improvement or at least a survival neutral change, the high radiation and poisonous metals, which will still be present in your pocket wastelands, will be malefic to life. As the rest of the world recovers, the lifeless bald spots are the areas you should stay away from.

Getting rid of the dead zones is a little more difficult because they are deadly. Start with a bunch slaves with shovels and bag up the top several feet of soil and any debris which has lasted this long. Put the bags, the debris and the dead slaves on horse drawn carts and have more slaves drive the carts towards a more distant pocket wasteland.

After a few days, send some more slaves on fresh horses after the carts. Have them add the earlier horsemen and horses (by now dead) onto the carts and continue the journey. Repeat until the cart reaches the distant pocket wasteland, then leave it there.

Bring in new top soil and plant something non-edible, like maybe some flowers or some bamboo. If those plants grow normally, you are probably done, but I still wouldn't eat anything that grew there for a few thousand years. If the plants don't grow, then repeat the whole process over, this time digging deeper.

Continue until the plants breed true and thrive.

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    $\begingroup$ The thing about plants is that they stay put. Radiant energy 24:7. If a seed falls in a radioactive place, no plant. But people move. As long as you dont curl up and go to sleep there you should be ok. Just cross the dead zone at a dead run, like you do any other spooky or stinky or spooky/stinky place. $\endgroup$
    – Willk
    Mar 7, 2021 at 4:23
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    $\begingroup$ @Willk: Re "If a seed falls in a radioactive place...", the problem with that is that everywhere is radioactive, and seeds grow just fine in most places. Only if the level is very high will the seed not grow - and it's far more likely to not grow for other reasons, like lack of water, wrong temperature, getting eaten by critters, not having a wildfire to spark germination... $\endgroup$
    – jamesqf
    Mar 7, 2021 at 17:04
  • $\begingroup$ @jamesqf, Good Point! Sounds like I should enhance my "detect deadlands method". How about we place some locally acclimated seedlings in paper pots within the bald spot which might be a deadland, then delivery water to them every day from a safe distance via some old pipe. If the seedlings grow or get eaten by critters then the land is probably good so let some poor people farm it for their own consumption. If they survive a few years then they become prosperous farmers whom you can now tax. If not... $\endgroup$ Mar 7, 2021 at 20:03
  • $\begingroup$ The volume and mass of the top few feet of soil sound prohibitive for a non-technological society to just move like that. $\endgroup$ Mar 7, 2021 at 21:45

They would learn to perceive subtle differences in which species thrive. While the evacuated surroundings of Chernobyl are a thriving wildlife refuge, a couple of species of bird, the great tit and the barn swallow, have struggled to adapt. There's a hypothesis that the biochemical requirements of their colored plumage compete with radiation resistance.


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