It isn't difficult. You just have to filter the oxygen you use when making new steel. But there is such a limited market that I doubt anyone bothers as enough old steel can be found. (I assume there are still plenty of old railway lines out there).
It would probably be possible to purify new steel through extensive re-smelting with filtered oxygen.
Wouldn't you also need a source of carbon that is not contaminated by nuclear fallout?
Afaik it's not the oxygen at all but rather radio isotopes in the air, it's the same reason we can't use carbon dating on anything since the first nuclear test because the isotope ratios are screwed up now and we can't estimate by how much.
You would, but coal from deep underground normally isn't. This stuff need not be strong. So you don't need a perfectly pure source of carbon, just one that isn't very radioactive. Old steel was made with carbon from coal. So while using coal isn't perfect, it's at least as good as the old steal.
If you wanted to you could probably centrifuge the carbon to filter out radioactive isotopes.
I don't know what steel you need but you don't use coal to make steel it would not be a good source of carbon the sulfur in it would make it very brittle.
From the looks of it much of the steel is made using charcoal which is very pure form of carbon and it has very little impurities in it, or coke which is a refined
fuel.
Charcoal definitely absorbs radioisotopes especially Carbon 14 from atmospheric CO2 but I don't know if C14 has any effect on the suitability of the steel for aforementioned use cases.
Centrifuging the carbon would be very expensive it would have to effectively be a process of converting carbon to gas (CO2 most likely) centrifuging it like one would enrich Uranium and then convert the CO2 back to carbon by assuming growing plants in an isolated environment and pumping the "distilled" CO2 into them.
Then you you'll have to burn the plants to make charcoal using non-atmospheric oxygen in order to prevent atmospheric radioisotopes from being an issue again.
So no I don't think anyone could centrifuge carbon to filter out the heavier elements, if anyone would do so that steel would become by far the most expensive metal on the planet by so many orders of magnitude I can't even begin to estimate it's price, you would effectively be making unobtainium.
I'm not sure about the general case, but here in Argentina one of our biggest steel factories had a very big eucalyptus forest just to make coal. From https://es.wikipedia.org/wiki/Aceros_Zapla_S.A
> "Aceros Zapla" (ex- "Altos Hornos Zapla") was a steel forest mining complex located in the department Palpalá province of Jujuy, Argentina. It was the first steel center of Argentina [...]
> It had 15,000 ha of a forest of 30 million eucalyptus trees to extract the necessary coal in the process, which was the village Forestry Center. [...]
I don't know for sure hence the question mark :)
What I know that Carbon 14 which is used for carbon dating is a cosmogenic isotope which is created when high energy cosmic rays hit carbon atoms in the atmosphere and in other places.
Nuclear tests release radiation which created much more carbon 14 than what was created with the natural process of absorbing cosmic rays.
I'm not sure what's the current source of carbon for steel, I don't think it's coal it was always too impure and contain allot of contaminants especially sulfur, and I that high end crucible and powdered metal steels are made with considerably more pure and precise sources of carbon, from wikipedia it seems that the source of carbon for modern steel is charcoal (which is affected by C14 imbalance) and coke (which i have no clue if it's affected by post nuclear blast radioisotopes or not) which is refined coal but this only references to modern steel (late 17th century onwards, and I'm not sure what is used today).
Funny, that's the same reason I used my question mark!
If you looked it up then you're already ahead of me. Sounds like non-coal carbon is common. Although it sounds like coal could be used as a source of low-radiation carbon if you wanted to make new low-radiation steel.
Along with asteroid mining will be space manufacturing, even 3D printing. It takes a lot less energy to move the finished product than the move the raw materials. 24x7 solar power, and less industrial pollution are other advantages of space manufacturing.
One could grab an asteroid primarily composed of water ice, obtain oxygen via hydrolysis and then use either earth mined iron or iron from a different asteroid type. Like I said though the idea is ridiculous. I'm also not sure how much nitrogen is needed in steel making or where the best extra planetary source would be.
No, the modern technique is to calibrate the device, and hence remove any background effects. Low background steel was used to calibrate some parent device, probably analog.
You can subtract the background, but you can't subtract the noise in the background, which goes as the square root of the number of background counts (typical rule of thumb). So you need low background if you want to detect weak signals above background in a finite amount of time.
This is also true, that's why pre-ww2 steel is used by national labs on specialized physics projects. On the other hand I am not aware of commercial medical products that use the stuff.
Yes, but the sample size might be limited, for instance for the whole body counter shown in the article. Anecdote: One of my friends in grad school was involved in an accident at a national lab, where some radioactive material was released into the air. He had to sit in a thing that counted gamma rays coming from him, to see if he had consumed any of the bad stuff, and it completely enclosed him in a large scintillation detector. So, he was the sample.
It's a bit like Jazz (and to a lessor extent most other forms of music) from before the 1980's, where they started that horrific over-production which made it sound plasticy and homogenous.
Pretty much any post 1980's Jazz. You can start off comparing Miles Davis's Amandla with anything he was doing in the '60s or '70s (Live Evil, On the Corner, Cellar Door Sessions etc). Herbie Hancock is another one who did stuff both pre and post 1980.
Amandla still has some great tracks, and there's some great post 1980s Jazz out there. But it always sounds like too much attention has been paid to how much reverb there is, how much echo on the drums, and to limit how much the guitar -if present- deviates from permitted parameters. Jazz from the '50s to '70s doesn't have these problems, and a lot of it was extremely well recorded, compared with all the dreadful sounding recordings of most rock from the '60s and '70s.
