12 ms·
It's always confused me how mined lead somehow has more radioactivity. Shouldn't the lead in the ground also have decayed over time? Also, it makes me wonder
by Natsu 6y ago
It's always confused me how mined lead somehow has more radioactivity. Shouldn't the lead in the ground also have decayed over time?
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.
- deleted 6y ago[deleted]
- toast0 6y ago> It's always confused me how mined lead somehow has more radioactivity. Shouldn't the lead in the ground also have decayed over time? 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.
- oh_sigh 6y agoI wonder why manufacturers don't just use filtered atmospheric air in the process to create low-background steel, if it is infact valuable.
- saagarjha 6y agoNot valuable enough to bother.
- nix23 6y agoSo salvage it from sunken ships is cheaper then?
- DonHopkins 6y agoJust cheaper for whoever salvages the ship -- somebody else had to pay for the sunken cost of building and sinking the ship.
- rrrrrrrrrrrryan 6y ago> sunken cost Nice.
- nix23 6y ago> somebody else had to pay for the sunken cost of building and sinking the ship Na remember it was war, so all the money went back to the economy :/
- fennecfoxen 6y agoMoney-oriented thinking is a road to economic misunderstanding. The economy is about stuff. In practice one often measures all the stuff using money, yes, because what else would one use? but as a proxy measure for its value; it's never actually about the money itself. (stuff = "final goods and services" to be technical)
- nix23 6y ago> because what else would one use? 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.
- fennecfoxen 6y agoNow you are measuring electricity instead of the light you read by, and fuel instead of the vacation trip you take with it. You have worsened the problem I refer to.
- 6y ago
- chrisbrandow 6y agoExtremely difficult to separate different molecules that differ by only the weight of a single neutron.
- ars 6y agoThey are using Oxygen, Oxygen can't become radioactive for longer than a few seconds anyway. All they need to do is filter for pure oxygen, nitrogen is fine as well. It's really just CO2 that's the problem.
- catalogia 6y agoI'm not sure about this; smelting lead is generally done in a blast furnace, fed with coke. Burning that coke is going to produce a ton of CO2. Is that good enough because the carbon in the coke is all very old? (Searching for information relating to C-14 and coal lead me to a bunch of wacko new earth creationist websites claiming that carbon dating indicates coal is young...) Also, maybe this isn't really a concern, but "high temperature and pure oxygen" makes me think "metal fire."
- awalton 6y agoSo this is all kinds of wrong. When you make steel, you typically use 99+% pure oxygen - modern mills do air separation and reject nitrogen and argon (which makes steel brittle when it's dissolved in) and basically anything they can reasonably separate out but oxygen. 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...
- garmaine 6y agoHow do you suggest filtering by isotope?
- TimSchumann 6y agoI mean, there are ways to do this. None of which are remotely cost effective.
- number6 6y agoCentrifuges
- renewiltord 6y agoThis stuff is useful, but it isn't that useful that you're going to sift and build an entire toolchain.
- ars 6y agoJust filter for oxygen. Radioactive oxygen doesn't last more than a few seconds. The issue is contamination with Carbon (CO2). Nitrogen also is not a problem.
- gruturo 6y agoAs others said, simply separating the CO2 away would mostly get rid of the problem - all non-stable isotopes of Oxygen have a max half life of 122 seconds, but, for the record, isotopic separation is easy when there is a very large difference in atomic weight. 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.
- awalton 6y agoGreat. None of these do anything for the real problem: Cobalt-60.
- deleted 6y ago[deleted]
- mcculley 6y agoWhat would be the timeframe over which one would make a profit? Our global financial system is based on the 30 year U.S. Treasury bond. There are no economic incentives to plan beyond 30 years.
- lukas099 6y agoThis is interesting. Can you point me to anything that will expand on/help me understand this?
- mcculley 6y agoI don't know of any good sources. But my understanding is that there are very few "Methuselah bonds" by which it is meant instruments that have lifespans of 50 years or more. So anybody with a profit motive has no advantage for putting money into something that would have a longer term focus. This explains to me why, for example, banks are still loaning money for buildings on Miami Beach. I would love to understand the dynamics better. It seems to me that only governments can be planning for longer terms. China, maybe?
- missedthecue 6y agoDykes are cheap.
- mcculley 6y agoI'm assuming you mean "dike" and not "dyke". Dikes will not protect property in Florida. Our buildings are sitting on top of porous limestone.
- missedthecue 6y agooof yes. Dyke is not what i meant. But florida already has a dike system. Hundreds of miles of them and they work quite well.
- 6y ago
- sandworm101 6y agoForget filters. It would have to be done in a vacuum and you would need to centrifuge the required gasses/carbon. It is possible in small batches, but the sunken ships do exist ready to harvest. Maybe in the future the market will come.
- deleted 6y ago[deleted]