Talk:Uranium

Template:Oldpeerreview Article changed over to new WikiProject Elements format by contributors to /Temp and mav 11:18, 9 Jan 2004 (UTC)

Information Sources

Data for the table was obtained from the sources listed on the subject page and WikiProject Elements but was reformatted and converted into SI units.

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Caution needs to be exercised in using the words fissile and fissionable.

U-238 is fissionable, and fast fission of U-238 delivers much of the power in three-stage fission-fusion-fission weapons. But it is not fissile, and contributes little to the power of a thermal or near-thermal power reactor (the PWR and BWR are not fully thermalised, owing to the competing need to reduce neutron losses).

U-235 and U-233 are fissile. Andrewa 17:01 20 Jun 2003 (UTC)

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Shouldn't the atomic weight (somewhere around 210-250 or so) be mentioned in the article? Ilyanep 22:03, 2 Sep 2003 (UTC)

In the table now. --mav 11:18, 9 Jan 2004 (UTC)

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Question: The text says "Because uranium has such a long radioactive half-life (4.47x109 years for U-238), the total amount of it on Earth stays almost the same." However, this isn't strictly true -- the half-life implies that there's only about half the amount of uranium left of what existed when the Earth was created. --Guan 19:38, 29 Nov 2004 (UTC)

Hmm, yeah, that doesn't make much sense, I don't think. I've removed it -- better to omit something like that than to have it be wrong, I think. If someone knows better, please re-insert it. --Fastfission 04:59, 10 Apr 2005 (UTC)

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This article should probably link to the articles on radiomentirc dating since there are a few radiometric dating methods than measure uranium isotopes--nixie 01:23, 10 Apr 2005 (UTC)

I added a small line about it to the "applications" section. --Fastfission 04:59, 10 Apr 2005 (UTC)

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anl.gov is down right now, so I can't check Fastfission's statement about the hazards of the decay products. However, U238 is an alpha emitter, the next two decay products are beta emitters, leaving U234. The alpha emitters are far more dangerous than beta's because alphas are typically very high energy, and for a given energy they are more damaging. U234 is an alpha, but the next decay product, Th230 has a half life of 80,000 years, so very little of it builds up in human timescales. As for U235, an alpha emitter, the next daughter is a beta emitter, and the next is Th 231 with a half life of 32,500 years, so it doesn't have time to build up. To summarize, the radiation of the parent uranium isotopes are far more hazardous than the daughters. pstudier 02:15, 2005 Apr 15 (UTC)

From ANL.gov (http://www.ead.anl.gov/pub/doc/Depleted-Uranium.pdf):

Uranium is not considered a chemical carcinogen. A second concern is for uranium deposited in bone, which can lead to bone cancer as a result of the ionizing radiation associated with the radioactive decay products. Uranium has caused reproductive problems in laboratory animals and developmental problems in young animals, but it is not known if these problems exist for humans.

Additionally, the decay series of uranium-238 is not trivial; it is what is responsible for radon gas and its own hazardous daughter products. As I understand it. (I'm not trying to trump up its danger, I'm just trying to get it right). --Fastfission 16:21, 15 Apr 2005 (UTC)

What I tried to say is that in a time scale of less than a few thousand years, the radioactivity of the daughters is insignificant because they don't have time to build up. You won't get significant radon from a piece of uranium in our lifetime. pstudier 21:28, 2005 Apr 15 (UTC)

So how does that accord with the information from Argonne and the fact that significant amounts of radon gas are emitted by uranium deposits? --Fastfission 22:33, 15 Apr 2005 (UTC)

The Argonne information conflicts with what the Uranium Information Centre Ltd [1] (http://www.uic.com.au/nip53.htm) and others have claimed. My guess is that it is only a minor hazard from the ionizing radiation of uranium. On the other hand, uranium deposits are generally much older than the few hundred thousand years it takes for the daughters to build up to equilibrium. Most obnoxious is radon because it is a gas that travels, and it deposits radioactive daughters Pb214 and Bi214 inside peoples lungs. Back before computer monitors were antistatic coated, one could wipe off the dust and detect Pb214 and the Bi214 with a Geiger counter, and watch it decay away. See Nuclear Electricity (http://www.uic.com.au/neAp2.htm) for a nice chart of the decay chains for U238 and U235. pstudier 22:58, 2005 Apr 15 (UTC)

So who do we go with? Argonne National Lab, or an organization which is funded by uranium miners and whose articles seem to be bent on portraying uranium as harmless? A google search for "uranium bone ionizing radiation site:.gov" seems to imply that there are quite a lot of US government sites out there which report that uranium deposits itself into bone and can be cancer causing.

From ANL.GOV Depleted Uranium (http://www.ead.anl.gov/pub/doc/Depleted-Uranium.pdf), we find that 30mg of uranium will cause Potential irreversible adverse effects. The specific activity of natural uranium is 6.77E-7 Ci/gram. So this 30mg is about 20,000 pCi. From ANL.GOV Uranium (http://www.ead.anl.gov/pub/doc/Uranium.pdf), we find that the lifetime cancer risk for ingesting U238 is 7.5E-11 /pCi. I use U238 as the numbers are just a bit less for the other isotopes. So if we eat 30mg of uranium we will get sick but have a lifetime risk of cancer of 1.5E-6, or 1.5 in a million. I would say that the risk of getting cancer by ingesting uranium is insignificant compared to getting sick by chemical poisoning. pstudier 00:54, 2005 Apr 16 (UTC)

I agree completely with that, but I think stating forcefully that it is not a carcinogen is simply incorrect, whether or not it is a very potent one. I'm aware, of course, that nearly every substance is a carcinogen to some degree, but I believe I once read (I can look this up) that the FDA defines (or maybe just defined) a chemical as a carcinogenic risk if it would cause cancer in 1 out of a million people, so 1.5 would be well within that. Anyway though, I can look that up. I don't remember the exact specification or whether it was in the past tense or not. In any event, I am again not trying to overstate the radioactive dangers of uranium (and I'm aware it is part of a more contentious debate over DU) because it is clear to me anyway that its toxicity dangers are far more likely to have an effect (and, in the case of DU weapons or nuclear weapons, the intended death-causing mechanisms are going to be much more effective than this sort of thing!), but I don't want to under-state it either.--Fastfission 03:08, 16 Apr 2005 (UTC)

How about Uranium is a very weak carcinogen. Chemical toxicity, especially to the kidneys, is a greater health risk than radiological effects. Applies even more so to depleted uranium because it is about half as radioactive. pstudier 23:16, 2005 Apr 16 (UTC)