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So... I've been playing a lot of the video game Subnautica lately, which put me in the mood for a "trying to cope with being marooned on an alien planet" sort of story; however, there's something in the game that's made me wonder about the logistics of a particular problem.

At one point in the game, you don a Radiation Suit and return to the crashed remains of your former spaceship in order to contain the radiation leak from when the FTL Drive Core blew up post-crash and keep it from spreading any further; while you're there, you discover that some parts of the ship are still surprisingly intact, including some of the crew quarters, and you can scavenge and collect various items for use in your own "base camp", including components for new technologies. In addition, you can also collect various decorative items that presumably belonged to the ship's late Crew Members, such as a model spaceship and a large plush toy.

This inspired me to include a scene of someone attempting similar containment of radiation from a crashed vessel discovering that some items belonging to a fellow officer's children- who survived the crash and who are now obviously feeling distressed and afraid back at the group's temporary shelter- and decides to bring the toys back to camp with them to return some sense of normalcy to the children's lives. However, given their close proximity to a large and presumably nuclear explosion and the continued leakage of radioactivity into the surrounding ocean, could something like a plastic model ship or a soft cloth toy be safely cleansed of radiation?

Some details about the explosion that might be useful:

  • Here’s some Footage of the actual Explosion and the description your PDA gives you, I’m not 100% sure if anyone can discern anything from this but I thought I’d include it anyway: https://youtu.be/rIlxEJG5whU

  • The ship seems to use a lot of Titanium, according to some flavor text on one of the equipment pieces

  • The crash took place on an ocean planet, and so the remainder of the ship was partially submerged in a large body of water (I think I remember learning something about Water affecting the spread of Radiation differently than air? Please correct me if I'm wrong about that)... For purposes of making this easier, let's say our marooned group ALSO crashed their ship into a sizable body of water

  • The actual compromised "Drive Core" was underwater, while the portion of the ship where the relatively intact crew quarters were was still above water and, if I remember correctly, positioned a few floors up and at the opposite end of the wreckage, so the objects in question likely never came into contact with any material leaking from the drive core post-explosion, if that matters? The crew quarters also still seemed to be sealed for the most part

  • I'm not sure what the Drive Core was made of or how it worked (the game gives you some technobabble about a "Dark-matter ion drive core", whatever that means), but it seems like there was at least some Uranium involved, as a lot of the other Nuclear-powered tech options in the game use it, so that's probably a good basis for what sort of thing we're dealing with here

  • These items are being retrieved somewhere between 24 hrs and 2.5 weeks after the initial explosion/event, exactly when in that window may depend on the answer to this question

So, with the above parameters in mind, here is my question: Would this kindhearted gesture be possible without Horribly Irradiating the Kids? Or would the would-be hero have to leave the toys behind due to health risks?

In fact, while we're on the subject, could your character in the GAME safely repurpose these items? Or is he going to survive the crash, the unforgiving elements, and the hostile alien wildlife, only to succumb to unexpected radiation poisoning?

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    $\begingroup$ (1) What kind of radiation? What are the radioactive isotopes producing it? How intense is the radioactivity? (2) What are the toys made of? Plastic? (3) How far are the toys from the radioactive source, and what is between them and said source? Uranium decays via alpha radiation, and alpha radiation is stopped by a sheet of paper, a few millimeters of water, and even a few centimeters of air; sitting two feet away from an unused nuclear fuel rod won't affect you in the least; so, no, it's not the uranium. $\endgroup$ – AlexP Jan 11 at 1:14
  • $\begingroup$ Hold on, I’ll see if I can find footage/stills from the game that might answer some of those questions... I guess that partly explains why you can just Pick Up Uranium and put it in your inventory XD Also, the toy ship seems to be plastic, but I’d guess that the Plushie is some Felt-like Cloth with cotton or maybe synthetic stuffing? $\endgroup$ – BonnetBee Jan 11 at 1:20
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    $\begingroup$ This makes me think of the Fukushima meltdown. There must have been families which left behind toys there. $\endgroup$ – Andrew Grimm Jan 11 at 4:51
  • $\begingroup$ Children tend to be pretty gross even before the radiation. Wash the toy before returning it on general principles. $\endgroup$ – user535733 Jan 11 at 15:45
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I think you could do it.

Stuff that is irradiated with electromagnetic radiation (like X-rays or gamma rays) does not generally become radioactive. That is how they can use radiation to preserve food. If you see fresh (plastic wrapped) meat for sale with an expiration date a month+ out you can assume it has been irradiated. It might not say on the label.

Fallout, though, is different. It is dust swept up in an explosion and contaminated with fission products. These are radioactive in all the different ways, and some isotopes could be strong enough to induce radioactivity in normal materials in the dust via particle radiation.

Nuclear fallout from a bomb loses potency pretty fast.

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

The danger of radiation from fallout also decreases rapidly with time due in large part to the exponential decay of the individual radionuclides. A book by Cresson H. Kearny presents data showing that for the first few days after the explosion, the radiation dose rate is reduced by a factor of ten for every seven-fold increase in the number of hours since the explosion. He presents data showing that "it takes about seven times as long for the dose rate to decay from 1000 roentgens per hour (1000 R/hr) to 10 R/hr (48 hours) as to decay from 1000 R/hr to 100 R/hr (7 hours)."[30] This is a fairly rough rule of thumb based on observed data, not a precise relation.

So if your toys were contaminated by dust produced in a similar explosion they too would lose potency pretty fast.

I think you could give saving them a shot. If you get the dust off that might be enough. Wash the plushy well with soap and water. Wipe the plastic thing off. Use a detector and see if they are still radioactive. If so, try it again. If still radioactive, wrap them up and set them aside (not under your pillow), then check them again a couple of months later.

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    $\begingroup$ That'll be one happy child! $\endgroup$ – elemtilas Jan 11 at 1:40
  • $\begingroup$ What about neutron activation? $\endgroup$ – 0something0 Jan 11 at 1:53
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    $\begingroup$ @0something0 That is the particle activation thing I mentioned. If you had a boatload of fission products landing on the toy that could induce its materials to be radioactive. But like the fallout dust, I do not think the radioactive isotopes made that way are very long lived. $\endgroup$ – Willk Jan 11 at 1:56
  • $\begingroup$ Radioacive fission products - recoil nuclei - get a tiny kick as well, those directly in contact could embed a small fraction of a micron under the surface, but the "boatload" aspect still applies. $\endgroup$ – uhoh Jan 11 at 5:53
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    $\begingroup$ @Mazura Unless you plan plan on crossing the Russian border, you should be safe from the Russian police. Chernobyl is located in Ukraine, very close to the border with Belarus. $\endgroup$ – VLAZ Jan 11 at 8:11

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