Low-Background Steel(en.wikipedia.org) |
Low-Background Steel(en.wikipedia.org) |
[0] https://www.theatlantic.com/science/archive/2019/10/search-d...
Also, it makes me wonder why someone enterprising hasn't stockpiled a few tons of the stuff somewhere to let it become low background lead for the future. You'd think that some government or another would be able to drop a million dollars on putting a lead stockpile somewhere safe for the future.
Looking into this a bit, it seems that the radiation in refined lead isn't coming from the lead ore, but from the other materials used in the smelting process. Old lead would have had time for all those things to decay.
I had some low radiation lead for a while, makes for an interesting curio. As I recall its providence was re-melted musket balls from a shipwreck in the Bahamas.
Is this a case of someone stumbling into the concept and wanting to share it with the world? Is there some trend in SV around low-background steel right now?
Genuinely curious about the phenomenon of posts around topics that have a great deal of understanding and aren’t necessarily trending in the general news cycle.
> By posting GPT generated text we’re polluting the data for its future versions
Edit: I'm pretty sure it was the knife steel post.
But I’d wager that Reddit curates their front page too. There’s no way an organic algorithm is populating the front page.
* First, the article implies that air continues to be the main reason for contamination of steel. It might have been the case, back when atmospheric levels for radioactive elements were higher. However now there is less contamination in the air [0], and the main source for contamination is recycled steel. Either because it itself is non-low-background steel or because e.g. medical radioactive sources were put into the scrap metal supply. See also this IAEA report on scrap metal [1].
* The article also says that the primary source for low background steel are shipwrecks, but I think that's an exaggeration. Especially, the topic came up on hn a few weeks ago and someone in the know debunked it [2].
[0]: https://upload.wikimedia.org/wikipedia/commons/e/e2/Radiocar...
[1]: http://web.archive.org/web/20111016193221/http://www.iaea.or...
https://physicsworld.com/a/nuclear-fallout-used-to-spot-fake...
I mean how do they create the instruments in the first place and keep the radiation low?
Could environmental markers like these be the way? After all, it’s how we look at the past today
Once we run out of cheaply salvageable steel, we'll likely turn to steel smelting processes that do not introduce air into the steel. These processes require dramatically more energy and are thus more expensive, but will still be way less expensive than attempting to salvage at deep ocean depths.
This would be exceptionally difficult, as oxygen is a basic requirement for steel making as we have ever known it. Steel is made from iron mixed with carbon and then heated to melt. Then oxygen is added which burns the excess carbon into carbon dioxide and reacts with all of the other reactive contaminants and brings them to the surface where they can be cupped off as slag. The melt is poured and cooled and you have steel. Early steel processes used air, blast into the furnace with high powered pumps. Modern steel is made with purified oxygen from cryogenic processes (and there are even designs floating around for steel mills which use the turboexpander from the oxygen processing to help generate electricity to drive the mill).
Without oxygen, you'd have to start with very, very clean iron ore (containing nothing but iron and whatever you wanted to alloy with the final steel), and add exactly the right amount of carbon (which is also exceptionally difficult, since carbon is light and the heat will want to make it sublime anyway). Odds are such a steel would still contain so much impurity as to require a second melt in a vacuum arc furnace, which also would dramatically drive up the cost.
While there might be a future making steel like this in space, I'm not counting it as very likely in the slightest to happen in this century.
It's much easier to use exceptionally clean oxygen - the mill could use an oxygen generation process (like a hydrogen peroxide chemical process plant being added to the mill), or by ultrafiltration of the process oxygen (which seems more realistic all told).
Air is perfectly fine. Both Oxygen and Nitrogen do not stay radioactive for longer than a few seconds. It's CO2 that is the problem, specifically the carbon.
And of course any other random impurity.
They could just use cryogenicaly distilled air, and take the nitrogen-oxygen part (the boiling points are very close).
Scuttled ships, well in theory anyways, shouldn't have had anyone on board.
Maybe we could encode some information in birdsong, tree rings, or the matting patterns drawn by fish in the seafloor. :)
But plastic is not a good candidate to hold messages for a long time. It degrades in a few years into some unusable stuff. Glass is a much better candidate.
I don't know there's much we could say that future civilizations would care to listen to.
Someone going on a binge from that, through discovering how Kodak found out about nukes from film and low background steel isnt a huge stretch either
The US sorta has a few things like that already--the oil reserve & the stockpile of helium, though I understand the latter is winding down still. Given the importance of those materials to science, I would think that there might be some scientifically-motivated project to protect our access to such things.
Dikes will not protect property in Florida. Our buildings are sitting on top of porous limestone.
But florida already has a dike system. Hundreds of miles of them and they work quite well.
All they need to do is filter for pure oxygen, nitrogen is fine as well.
It's really just CO2 that's the problem.
In Uranium's case it's difficult because it's 235/238 = 1.28% (actually way worse - Uranium hexafluoride is used, which adds 114 units, bringing the ratio down to 0.86%)
In Oxygen's case the ratio would be at least 6.6% (15 vs 16).
Most importantly in Uranium you are interested in the tiny amount of U235, while in Oxygen you'd be interested in the huge bulk of O16, O17, O18, which are the stable isotopes. O16 alone is 99.762% of all Oxygen, and you can afford to lose half in your centrifuge if it spares you a few cycles, it's not exactly hard to come by.
The issue is contamination with Carbon (CO2). Nitrogen also is not a problem.
But furthermore, it's not radioactive oxygen isotopes that get into the steel in the first place - they're scant to non-existent in nature, since all three common isotopes of oxygen are stable and most of the rest decay in seconds. It's other radioactive isotopes in the air from the bomb tests.
99+% isn't 100%, and it turns out those tiny fractions of a percent of junk contain the isotopes that are the real problem, namely Cobalt-60 created by the nuclear tests. Carbon-14 isn't nearly as big of a problem, since its decay mode is just beta and can be designed around, but the gamma decay from Cobalt-60 contamination is much harder to deal with.
Furthermore, because of Cobalt's position on the periodic table and the desire to have a small amount of cobalt in steel anyways to give it better working properties, it's not something that's easily filtered out, even in processes that reform steel like vacuum remelting which exist to make mechanically harder and better quality steel by slow melting and recrystalization. Once the Cobalt's in there, it's in there - you just have to wait for it to decay.
As it turns out, we're in luck, most of the fallout from those bomb tests has passed through numerous half-lives and is much less of a problem today than it was in the 1980s and 1990s when the low background stuff became such a hot commodity. So it doesn't really matter as much that we're running out. Furthermore, oxygen separation technologies and cryogenic liquid handling have improved, so we can do an even better job keeping contamination out. If someone wanted to set up a low background mill, they probably could do it today with commodity molecular sieves and centrifugation of the oxygen rejecting all but the light fraction...
Also, what's in the lead? I didn't think we wanted CO2 in lead but I'm really not sure what impurities it might have naturally.
So the term "fallout" is actually a pretty piece of propaganda. While a lot of it did or does indeed "fall out", there's still a lot of radioactivity in the air and on the surface from those nuclear tests in the form of fine particulate. It's in the fine dust all around you as 100nm and smaller particles, dancing around the air through Brownian motion. It's all over everything all of the time. It's in the water and the ocean. Nanograms here and there and everywhere. Not enough to really cause you health problems anymore, but plenty enough to increase the background radiation of the entire surface of the planet by a tiny amount.
How it gets into the steel is through the actual blasting of oxygen into the steel - hundreds of cubic meters of oxygen are used per ton of steel made, concentrating those tiny particulates into the steel they're going into and dissolving them throughout the melt, which is precisely why using ultrapure oxygen and vacuum processes could be used to make lower background steel today... if there was high enough demand to justify the absurd cost of that kind of handling. Fortunately though, there was plenty of steel made before the 1940s, and the demand is not all that high since it's usually used as a shielding material and not as large structural elements. As long as they don't remelt it, or do so in a high vacuum reformer, the metal can retain its low background nature.
Intermediate-lived gamma-emitting isotopes (cobalt-60, strontium-90, cesium-137, and so on) are the particular problem children of nuclear fallout in steel making. The cesium and strontium are largely removed by the same processes as steel is made in the first place - they're simply reactive enough to bond with the silicon and carbon and aluminum impurities being removed and will happily exclude the majority of themselves as part of the slag. So while they do contribute to the background, they're not the main problem. Cobalt, on the other hand, is right next to iron on the periodic table and its happy to stay stuck to the iron, even through rounds of recrystallization. Once the cobalt is in the steel, it's in there until it decays away to nickel over the next century or so. (This is also why it's much less of a problem now than it was even 20 years ago; the halflife of cobalt-60 is about 5 years, which means much of it from the nuclear testing is already gone - most of what remains is from nuclear reactor releases and neutron activation products.)
The more sensitive your instrument needs to be, the more radioactive contamination wrecks your instrument, which is already why physics experiments have to go to extreme lengths to keep everything clean of dust and debris, and are often located underground or underwater to avoid exposure to cosmic rays and atmospheric muons decaying. But the even higher sensitivity experiments like dark matter searches and measurements of cosmic background radiation have little choice but to reach for low background steels and lead as shielding material.
Also, maybe this isn't really a concern, but "high temperature and pure oxygen" makes me think "metal fire."
Nice.
Na remember it was war, so all the money went back to the economy :/
(stuff = "final goods and services" to be technical)
Energy witch can be food, oil, gas, the energy transformator is a human (or his brain) a maschine or a animal, and the exchange between energie to the endresult is often money. So money/exchangemedium has just the worth both partys agreed on.
For your vacation trip you NEED energie in form of food an fuel, the vehicle you travel in, is made by food and fuel...exacly the same.
If the transport company accept your fuel (or workforce witch again is fulled by energie (your food)) as payment, you exchanged energie to energie, probably they dont and thats why you use a exchangemedium called money.
EDIT: You dont have to messure anything, if you need light exchange energy to light, travel exchange fuel to distance, working body food to (body)-energy. To make stuff you calculate the sum of the energie needed for, and thats the price of the product, sure exeptions like apple exists ;)
consider the 'light' market:
https://ourworldindata.org/uploads/2013/12/Trends-in-the-Pri...
