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I am working on a small worldbuilding project.

The world this takes place in is littered with 5,000 year old (estimate) ruins, and these ruins are full of decaying radioactive material. In most locations, it's not too much. At most, 50-150 mSv an hour. Not good for one's health, but not so deadly as to prevent Ruin Haunters from scouring the region. In some pockets however, one can reach 5,000 to 6,000 mSv an hour. Haunters have made the connection between lead and stopping these 'cursed spirits' from being able to corrupt them, and some have come up with the idea of lead plate or scale armor to fend off these 'cursed spirits.'

The Haunters have access to manufacturing technologies up until 1900, a significant improvement to the 15th century world that existed not even a century prior. Haunters work in crews of 4-6 and stay within ruins for two weeks on average. Is this armor feasible?

For more context, see Radiation poisoning and primitive peoples.

[EDIT 2/2/22] All the answers I have received have been very helpful in their own ways. I find it difficult to select a single answer as most helpful - and so I shall select none. Thank you for responding, you have all been most beneficent.

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    $\begingroup$ Note that lead is quite soft. Lead plate armor isn't going to work, just for mechanical reasons: lead sheet thin enough to carry will flex and tear. This doesn't doom the idea of lead armor, you're just going to need something more like scale armor, or sheets of leather sewn together around lead foil. $\endgroup$ Jan 30, 2022 at 14:22
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    $\begingroup$ don't forget masks. no residual radiation is more dangerous than inhaling radioactive dust. $\endgroup$ Jan 30, 2022 at 18:29
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    $\begingroup$ @ChristopherJamesHuff Lead can be alloyed. Soft isn't the problem. Weight might be, though. Even if you could get away with a 5mm thickness, you might need powered armor to move around. What I don't know is how thin the lead can get before it looses its effectiveness. $\endgroup$
    – JBH
    Jan 30, 2022 at 19:14
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    $\begingroup$ @ChristopherJamesHuff perhaps be inspired by the lead aprons used in radiology (Google image search) $\endgroup$
    – Chris H
    Jan 31, 2022 at 9:38
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    $\begingroup$ @JonCuster Tungsten was discovered in 1783. The first successful arc furnace was built in 1888. People were experimenting with tungsten prior to 1900, just nobody had a reason to do much with it until electricity became cheap enough to use for general lighting. Methinks a landscape dotted with radioactive ruins and the need for strong, low-volume shielding would provide a potential, alternative development incentive. $\endgroup$
    – Perkins
    Jan 31, 2022 at 21:16

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Not a lot. Yet a lot.

After quickly reading some articles I found that they use lead aprons to protect themselves during things like x-ray and such. They are about 7 to 14 kg (10-20 pounds), so not very heavy. This isn't much radiation compared to what you're asking. Though. I would go much stronger.

Another article stated that radiation can be reduced with 95 to 98% with 2,8 to 18mm (0,71 inch) thick lead sheets. This in some ways isn't much and would reduce the 5000-6000 mSv to 250-300 mSv. Still not healthy, but a great deal better! The weight? A quick back of the envelope calculation says it's 19 to 504kg (42 to 1111 pounds) for the lower bound, 38 to 1008kg (84 to 2222 pounds) for the upper bounds. That is because the aprons generally have 0,25mm thick lead shields, while you require 11 to 72 times as much. Aprons are often single sided as you know where the radiation is coming from.

This is likely too high. I've added the full weight of the apron, but there's probably some weight not belonging to the lead in the apron. Let's be extremely generous and say it's 10%. That's still very roughly 17-900kg (38 to 2000 pounds).

Mind you, this is for either only front or both side aprons.

An armour requiring to only protect the vitals (torso, neck, head, genitals) would in most cases be too heavy to carry. Ranging from difficult to impossible. That would still leave many sensitive areas like some bone marrow open.

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    $\begingroup$ Far too heavy to be completely covered in lead, it seems. It looks like I would need to figure out a more hybrid approach, mixing various forms of protection. $\endgroup$
    – Preott
    Jan 31, 2022 at 7:41
  • $\begingroup$ Looking at current handling of x-rays, I think just covering your torso and maybe a helmet can already give you a significant chunk of the protection for a small percentage of the weight. In general, loosing a few cells in the bones or muscles of the arms and legs is a lot less harmful than loosing the same number of cells in the brain or some inner organ. $\endgroup$
    – quarague
    Jan 31, 2022 at 9:56
  • $\begingroup$ A lead jockstrap will be desirable for most men... $\endgroup$
    – Jon Custer
    Jan 31, 2022 at 18:00
  • $\begingroup$ Don't forget the need for air holes and eye holes/slots/glass that can't be fully protected. Even leaded glass isn't enough. $\endgroup$ Jan 31, 2022 at 21:32
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Lets have a quick think about what sort of radioactive materials are likely to be long enough lived (given the 5000 year delay since the end of their production you mentioned in the older question) and produce gamma rays.

Assuming that controlled nuclear fission is the main source of the radioactives involved here, you'd expect to have things like 126Sn, 93Zr and 129I. These are beta-emitters, but their decay products are 126Sb, 93Nb and 129Xe, respectively, sometimes in an excited state. These decay by various means, the excited states release 40.4keV, 30.8keV and 39.6keV gamma rays respectively and these are the probably the main sources of gamma radiation that you'll be dealing with.

NIST has helpfully compiled a list of x-ray mass attenuation coefficients for us with a wide range of photon energies and materials. For simplicity, lets assume we're only dealing with 40keV photons. This gives us a mass attenuation coefficient $\mu$ of 14.36cm2/g for lead, 3.629cm2/g for iron and 5.685cm2/g for aluminium (which is difficult to produce, but may be straightfoward to scavenge, post-apocalypse).

In order to reduce incoming radiation to 1% of its initial flux, you need a layer of material with density $\rho$, thickness $\ell$ and mass attenuation coefficient $\mu$: $0.01 = e^{-\mu \rho\ell}$. The thickness will therefore be $\ell = {\log(0.01) \over - \mu \rho}$. For lead, this would be .28mm, for iron 1.6mm and for aluminium 3mm. I'm not quite sure how much material you'd need to make an all-enclosing radiation-onesie, but lets say it is 3m2. That gives your 99% shielding a weight of 9.6kg for lead, 38kg for iron or 24kg for aluminium. A double thickness shield would reduce radiation to 0.01% of its initial flux, and would weigh twice as much.

Obviously lead, if you can find it, is the ideal material to use here. Other scavengable materials can also work though they'll be much heavier... but note that a 1.6mm onesie made from iron is a reasonable suit of armor and a useful thing to have if you're expecting to get into a fight and haven't re-invented firearms yet.


However.

As L.Dutch pointed out (and I implied in my last answer though admittedly didn't make it explicit) the bigger risk is in inhaled and ingested radioactives. That long-lived waste decays via beta-emission, and whilst beta particles generally aren't excessively dangerous on the outside they are pretty bad news on the inside.

Modelling risks of radiation exposure is hard, so I don't think I'm going to try that right now. But I have a sneaking suspicion that the background level of gamma radiation might not actually be that bad, and as long as you're not trying to spend long periods of time in the hot zone you might not have to worry about it very much. But what you very much definitely should not do is drink the water, forage or hunt. You need a decent fabric dust mask (you could describe this as a kind of veil, if you were superstitiously inclined!) and if you do get dusty and dirty whilst you're in the bad lands then you should make sure to wash it all downstream of your village, and ideally before taking off your mask. Post expedition ritual cleansing (scrub all that contaminated mud out from under your fingernails!) is likely to be more beneficial than a lead foil onesie.

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A lead armor will work only for protecting the body from radiation coming from the outside (and will be quite cumbersome to wear, but one can't be picky here).

An alternative to lead, or an integration, can be represented by water cushions, which would be more flexible and could also be used as drinking water on the way back.

For radiation coming from inside the body, an armor will do nothing. And in a highly radioactive environment, one needs just to breathe some dust to let radioactivity past the lead armor and directly into the body, where it will irradiate at libitum.

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  • $\begingroup$ You'd need more water than you could reasonably carry. You'd need a literal tank ;-) $\endgroup$ Jan 30, 2022 at 16:31
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    $\begingroup$ I'm surprised this isn't higher voted. You don't worry about the radiation in the zone — you worry about it staying with you in your lungs and gut. Armor does nothing if you're breathing radioactive particles "until death" after. $\endgroup$ Jan 31, 2022 at 2:17
  • $\begingroup$ Water cushions would be a great outer layer I feel. Perhaps on top of lighter scale or chain lead armor. This would certainly be a better option for people in warmer climates. As for preventing radiated dust, a thickly woven cloth headwrap or even an early gas mask for the richer haunters would be in order. I don't know how I missed that crucial detail, thank you. $\endgroup$
    – Preott
    Jan 31, 2022 at 7:38
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    $\begingroup$ Water is used to attenuate particle radiation. Gamma radiation is electromagnetic. You want stuff with lots of electrons to interact with, hence high Z elements. $\endgroup$
    – Jens
    Jan 31, 2022 at 13:27
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Lead. Bah. You want to look like a pipe? They will probably call you "The Pipe". They already do? Hmmm. In any case when am exploring the glowing ruins I will be wearing GOLD!

GOLD ARMOR

source

Gold is denser than lead (19 vs 11 mg/cc) so provides better radiation protection. Gold is much stronger with a tensile strength an order of magnitude greater than lead. And gold looks awesome!


For this question I think "gold plate mail!" is enough. Because there will be no end to complaints about making real armor, armor that is good for fighting, making lead aprons, making alloys, no radiation after 5000 years etc etc.

I am ok with an image of scale mail constructed using gold Krugerrands.

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    $\begingroup$ Interestingly, gold is not as good at stopping 40keV photons as lead, despite its higher density. Clearly the increased density of nuclei doesn't offset the smaller number of electrons per nucleus, and it is that electron cloud that will be stopping gamma rays. It isn't much worse though... about 10% heavier and the foil can be 30% thinner, for the same level of protection as lead. $\endgroup$ Jan 30, 2022 at 16:28
  • $\begingroup$ @StarfishPrime - I did not realize it was the electrons that were doing the work! If you have a link for me that would be great. One could infer from this that a negatively charged surface with extra electrons would block radiation better than the same surface with no charge and either would be better than positive charge. That would be a good science fair experiment. Electrons are lighter than lead! $\endgroup$
    – Willk
    Jan 30, 2022 at 17:35
  • $\begingroup$ Getting the charge density high enough would be a challenge... regular matter is pretty good at that sort of thing. Irritatingly, I don't seem to have a nice resource that unambiguously states that electrons do the blocking, yet it is clear that high-Z numbers and high density is the way to shield against electromagnetic radiation. Conversely, you want a high density of nuclei to block neutron and heavy ion radiation, so lightweight plastics and waxes (and indeed water) are best there. I'll keep looking. $\endgroup$ Jan 30, 2022 at 18:35
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    $\begingroup$ Voted this up for esthetical reasons.. @StarfishPrime on quora they agree gold and lead have equal protection against gamma radiation, quora.com/… they use this calculator physics.nist.gov/PhysRefData/FFast/html/form.html $\endgroup$
    – Goodies
    Jan 30, 2022 at 19:02
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    $\begingroup$ @willk at higher energies (say, 1MeV gammas) is is, in fact, electron density that matters more because the main way those gamma rays interact is via a different process, compton scattering, and electron density is the most important factor there. Gold is better than lead at higher energy levels, but for long-lived radioactive waste such as the OP is interested in, those high energy levels are unlikely to occur. $\endgroup$ Jan 30, 2022 at 20:05
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Yes, it is feasible.

Personal protective devices include lead aprons, thyroid shields, lead glasses, caps, and gloves.

Lead Aprons

An apron with 0.5 mm thickness can attenuate approximately 90% or more of the scatter radiation. A standard lead apron weighs approximately 7 kg, which could cause the development of back problems.

Lead glasses

The lens of the eye is the most radiation-sensitive part of the body, therefore, wearing lead glasses is essential.

Lead glass, commonly called crystal, is a variety of glass in which lead replaces the calcium content of a typical potash glass. George Ravenscroft (1618–1681) was the first to produce clear lead crystal glassware on an industrial scale.

Lead glasses with 0.5 or 0.75 mm thickness can reduce more than 95% of scatter radiation.

Thyroid shields

The thyroid gland should be protected because it is vulnerable to scatter radiation. The annual maximum permissible dose recommended to the thyroid is 300 mSv. A thyroid shield can reduce the effective dose by 2.5 times and the total exposure by almost 50%. Therefore, thyroid shields should have at least 0.5 mm lead equivalent thickness for neck and thyroid protection.

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Another possibility here if the hunters are organized and working on a large scale:

Instead of trying to wear armor they make a series of armor plates which are positioned to protect a safe path.

Note, also, that they should know about concrete. To protect areas that are going to be accessed many times (say, the approach to the ruins) make some concrete walls.

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