Talk:Thorium/Archive 1

Archive 1

Archive 2

Heinlein universe

Robert A. Heinlein envisioned thorium as being the principal fuel of the advanced space-travelling civilizations described in his novels Have Space Suit—Will Travel and Citizen of the Galaxy. Does that have a place in this article? Ellsworth 16:32, 10 May 2004 (UTC)

Ra = radium, not radon. Chris

Untitled

Article changed over to new Wikipedia:WikiProject Elements format by Mkweise and Dwmyers 14:41 Mar 3, 2003 (UTC). Elementbox converted 10:37, 17 July 2005 by Femto (previous revision was that of 23:52, 10 July 2005).

Information Sources

Some of the text in this entry was rewritten from Los Alamos National Laboratory - Thorium. Additional text was taken directly from USGS Thorium Statistics and Information, from the Elements database 20001107 (via dict.org), Webster's Revised Unabridged Dictionary (1913) (via dict.org) and WordNet (r) 1.7 (via dict.org). Data for the table was obtained from the sources listed on the subject page and Wikipedia:WikiProject Elements but was reformatted and converted into SI units.

Thorium as nuclear fuel

Much development work is still required before the thorium fuel cycle can be commercialised, and the effort required seems unlikely while (or where) abundant uranium is available.

It may seem unlikely, but it's exactly what India is doing! Is this deliberately phrased to exclude India, and so make it sound as though it's not happening, while not actually denying that in fact it is? Andrewa 18:15, 4 February 2006 (UTC)

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Thorium may be used in subcritical reactors instead of uranium as fuel. This produces less waste and cannot melt down.

This was wrong, Thorium can be used in critical reactors, too, and produces only less amounts of transuranic wastes. Most importantly, subcritical reactors aren't meltdown-proof, they could melt from after heat just like critical reactors could. This is probably not the right place to discuss all aspects of Thorium as nuclear fuel. 88.74.137.143 14:24, 21 January 2007 (UTC)

I have added a couple lines here, they are difficult to merge into the current text which I believe is in error. I did not want to mention the company that is commercializing the seed and blanket technology by name (Thorium Power Ltd.) but the process by which the Indians are proceeding is the breed - extract - feed cycle, which is still years away from being viable and what is referred to in the part just past my insertion as being untenable with high fuel fabrication costs. The cost estimates for Thorium power designs is 15% less than conventional 4% enriched uranium.

I believe that the first line in thread is wrong. Much work has been completed and Thorium utilization may be just around the corner.

Adapter (talk) 23:13, 9 March 2008 (UTC)

World of Warcraft

Thorium is also a fictional metal in the Warcraft universe, and can be mined in World of Warcraft. Why why why does this exist in this topic... :

>>Other Usages

Thorium is a strong metal in the Warcraft game universe, and more specifically World of Warcraft. In World of Warcraft, this is one of the highest-level mineable metals, and Alchemists can transmute it to Arcanite.

Thorium from WoW bears little in common with the properties of the real-world element Thorium. 83.71.144.13 (talk • contribs) 09:49, 21 July 2005 (UTC)~

References to this get removed, added, removed, added again... Everybody should agree that the WoW metal is very different from the real one, and as such, not a fictional use of this element. (I think even Heinlein's 'real' fictional use would be pushing it, notability-wise.) The borrowed name might deserve a disambiguation link to a separate Thorium (Warcraft) article though, if the material is notable enough in the Warcraft universe. Femto 14:57, 2 April 2006 (UTC)

Added "See thorium's entries at fictional applications of real materials" which seems to be the most elegant solution. Femto 14:36, 16 April 2006 (UTC)

I think anything to get the general public interested in science is worth it. —The preceding unsigned comment was added by 71.222.149.170 (talk • contribs) .

This page needs to show some boobies, that'll catch their interest. Unfortunately, it would be just as unrelated to the topic as fictional alchemists and space travellers. Femto 13:14, 30 September 2006 (UTC)

In popular culture

I removed this statement

In 1999, a group of University of Chicago students taking part in the annual scavenger hunt built a small, working nuclear reactor.

which someone had put a {fact} tag on. (The sentence was originally added at 13:33, 12 May 2006 by User:Danpat.)

As it happens, the University of Chicago Scavenger Hunt article contains a link to http://www-news.uchicago.edu/citations/99/990519.scavhunt.nyt.html which does corroborate the scavenger hunt story. However, I can't see any evidence that Thorium was specifically involved. (That article mentions only Plutonium.) —Steve Summit (talk) 04:11, 11 October 2006 (UTC)

It is difficult to determine whether David Hahn is a fictional or real person. I thought "in popular culture" implied he was from a TV movie etc. --Dunkankan 01:32, 21 October 2006 (UTC)

Norway lucky as always

Like the oil, Norway still has the luck on sitting some huge quantities of valuables. I just think it is fun and strange at the same time.

Nor does rime with Thor. -lysdexia 03:05, 2 February 2007 (UTC)

Translation into Chinese Wikipedia

The capitles Distribution and Thorium as a nuclear fuel of the version 15:31, 26 October 2007 TheoClarke are translated into Chinese Wikipedia.--Philopp 10:29, 3 November 2007 (UTC)

radioactivity versus half-life?

There are substantial deposits in several countries. 232Th decays very slowly (its half-life is about three times the age of the earth) but other thorium isotopes occur in the thorium and uranium decay chains. Most of these are short-lived and hence much more radioactive than 232Th, though on a mass basis they are negligible. India is believed to have 25% of the world's Thorium reserves. [5]

has a phrase in it which didn't look right to me.... "Most of these are short-lived and hence much more radioactive ..."

is an element more radioactive if it has a short half-life, or does it have a short half-life because it's more radioactive??

i'd suggest that the phrase be replaced by

"Most of these, much more radioactive than 232Th, are short-lived, though on a mass basis they are negligible."

does this make grammatical and scientific sense at the same time?

thanks for considering... Plusaf (talk) 01:22, 28 November 2007 (UTC)plusaf

More radioactive and shorter half-life are pretty much the same thing, I think the original phrasing helps emphasize that.

Hooray for Spelling!

Thorium has been extracted chiefly from monazite through a multi-stage process. In the first stage, the monazite sand is dissolved in an anorganic acid such as sulfuric acid (H2SO4).

Is anorganic a word? Even so, inorganic might be more appropriate since it's closer to standard IUPAC jargon.

71.139.5.47 (talk) 20:10, 14 June 2008 (UTC)dlj

It should be inorganic, so I've changed it. Maybe it was a "Germanism" that slipped through (from the German anorganische). --Itub (talk) 09:06, 16 June 2008 (UTC)

Is the reference given right?

This is regarding the reference provided for the list of countries having thorium resources. The ranking does not match with the ranking provided in the following link: http://www.world-nuclear.org/info/inf62.html

Which one do you think is right?

) —Preceding unsigned comment added by Subinvarghesein (talk • contribs) 14:08, 16 October 2008 (UTC)

Unrealistic Impression of Thorium Abundance

I am going to modify following thorium abundance statement

“Theoretically thorium is more suitable fuel source than uranium: thorium is about 550 times more abundant in nature than uranium-235”

This is like comparing apples to oranges. Thorium is not comparable to Uranium-235. Thorium is a fuel source, but U-235 is a fuel.

Thorium is more comparable to U-238, both are fuel sources fertile by more or less comparable breeding process, both producing more or less comparable breeding products (i.e. U-233 and Plutonium respectively).

And on statement,,,, “potentially all of thorium fuel can be usefully burned in nuclear fission (current state of the art uranium based reactors burn only about 1-2% of fuel)”

Again, if the reactor is to include breeding steps, then lets use same standard for uranium, the U-238 can also be made to burn a lot of it (“potentially” all of it). Practically may be not all of uranium is burned but significantly more than 1-2% has been practically demonstrated at commercial scale in many breeding reactors. Has thorium been demonstrated of at commercial scale of it’s “potential” of burning of all the fuel? If no then lets not make this theoretical “potential” appear as better than “state of the art uranium based reactors” because theoretical potential of burning all fuel is same for both thorium and uranium, and practical demonstrations of both breeding are not far distant off either. Mnyaseen (talk) 19:52, 15 February 2009 (UTC)

Most sources state that there are 2-3 ppm uranium concentration in the Earth's crust vs 12 ppm for thorium - moreover since nobody has ever cared about thorium deposits it is much more likely that there are yet-unaccounted thorium reserves (than uranium).

80.52.239.106 (talk) 12:43, 18 February 2009 (UTC)

Introduction could use change of focus

The introduction has multiple paragraphs about the thorium nuclear cycle, but says almost nothing about thorium itself (appearance, discovery, history, chemical properties, uses). (Compare with the introduction for a random element such as Hafnium.) I suggest moving most of the nuclear fuel stuff out of the introduction (maybe also expand the Thorium fuel cycle introduction which is pretty brief), and making the Thorium introduction cover thorium in general. Billgordon1099 (talk) 16:56, 6 October 2010 (UTC)

Better to compare it with plutonium and uranium. This is what I will do.--Stone (talk) 19:07, 6 October 2010 (UTC)

article is logically inconsistent and has serious NPOV problems

This page appears to be the usual list of thorium shill talking points from pro-pollution free market ideologues like Robert Jastrow and Fred Singer. These are the same people the tobacco industry hired to dispute the toxicity of cigarette smoke, the same people the oil industry pays to dispute the reality of global climate change, the same people that convinced Ronald Reagan that acid rain was too expensive to remediate. Like most of the pseudo-science these people promote, the page makes an emotional appeal to techno-fetishism but does not make good logical sense. For example, it claims that thorium reactors are safer than conventional uranium and plutonium reactors, but a conventional fission reaction from uranium or plutonium is required to initiate a thorium breeder. Logically, since process A is a necessary and integral part of process B, it is impossible for process B to be safer than process A. The page also claims that thorium-cycle breeder reactors cannot be used to create weapons-grade fissionables, but this is not true - although a thorium reactor could theoretically be carefully managed to create only very small amounts of plutonium which are then consumed, all proposed reactor designs either produce plenty of plutonium (as per the proposed multi-stage system in India) or can be trivially modified to generate any amount of weapons materials. The page also implies that thorium reactors do not produce significant waste, but this is not true unless the wastes are subject to expensive and difficult reprocessing - a claim that can be made by any fission process, since fission entails transmutation. A more balanced, less breathlessly overenthusiastic review of thorium reactor issues and technology can be found here: http://www.world-nuclear.org/info/inf62.html . Thorium may be worth using as a fuel, but there's no need to hard-sell Seth Shaw's WNA talking points on Wikipedia. --Charlie — Preceding unsigned comment added by 205.153.180.229 (talk) 21:11, 2 June 2011 (UTC)

We know - it is past time the worst of that is removed. I have since hide much of the worst text. More work is needed. Please mention other specific passages that need to go. --mav (reviews needed)

Radioactive lenses

Certain old camera lenses - particularly old Pentax Takumar screwmount lenses - are notorious nowadays for being slightly radioactive, on account of thorium in the glass.[1][2] This causes part of the lens to yellow with age, which can be cured by exposing the lens to ultraviolet light (so the theory goes - it might just be strong visible light that does it).[3] It would be very interesting if someone who knows more about radioactivity and lenses that myself could add a paragraph or two to the article, explaining why the lens yellows, and why ultraviolet cures it, and whether or not the lenses are hazardous. -Ashley Pomeroy (talk) 13:22, 15 November 2008 (UTC)

I doubt that the lenses are hazardous unless you grind to a fine powder first and then eat them or inhale them. ;-) The half-life of thorium is extremely long, resulting in very low activity; it decays via alpha particles, which have so little penetrating power than most of them won't even leave the lens (they can be stopped by a sheet of paper and don't penetrate very deep into the skin if you are exposed externally). Other types of radiation may be produced by the decay products of thorium, but their activity is also limited by the long half life of thorium itself.

I have no idea why the lens yellows, that's a very interesting question. --Itub (talk) 10:56, 16 November 2008 (UTC)

Most glasses are susceptible to produce colour centres when irradiated by radiactive or cosmic rays. Glas in Space has always to prove that it it is OK with radiation. --Stone (talk) 19:26, 28 December 2010 (UTC)

Article needs image!

Thorium is a fairly common element. Why isn't there a picture? --Ferocious Flying Ferrets 19:26, 9 April 2010 (UTC)

Yes please. I can't find one anywhere! Llywelyn2000 (talk) 18:52, 14 June 2010 (UTC)

Maybe this website has the image? I'm not sure if it is pure or if it is ore. http://www.popsci.com/technology/article/2010-08/thorium-reactors-could-wean-world-oil-just-five-years Hackne (talk) 15:15, 28 December 2010 (UTC)

Non displaying text moved as archive

The following text was included within the lead but did not display. I added the citation list for easier reference in case some of this is added to the article. --Wikiwatcher1 (talk) 03:18, 13 October 2010 (UTC)

Thorium was successfully used as a breeding (fertile) source for nuclear fuel – uranium (233) in themolten-salt reactor experiment (MSR) from 1964 to 1969 (producing thermal energy for heat exchange to air or liquids), as well as in several light water reactors using solid fuel composed of a mixture of ²³²Th and ²³³U, including theShippingport Atomic Power Station (operation commenced 1957, decommissioned in 1982), but a thorium-uranium mix was only used at end of life to demonstrate Th-to-U breeding. Currently, the Japanese Fuji project and officials in India are advocating a thorium-based nuclear program, and a seed-and-blanket fuel utilizing thorium is undergoing irradiation testing at the Kurchatov Institute in Moscow.

Advocates of the use of thorium as the fuel source for nuclear reactors, such as Nobel laureate Carlo Rubbia, state that they can be built to operate significantly more cleanly than uranium-based power plants as the waste products are much easier to handle. According to Rubbia, a ton of thorium produces the same energy as 200 tons of uranium, or 3.5 million tons of coal. Edward Teller, co-founder and director of Lawrence Livermore National Laboratory, promoted thorium energy until his death, and scientists in France, Japan, India, and Russia are now creating their own thorium-based power plants. One leading commentator is calling for the creation of a new Manhattan Project, stating that the use of thorium fuel for energy would "reinvent the global energy landscape . . . and an end to our dependence on fossil fuels within three to five years."

When used in molten-salt reactors, thorium bred to ²³³U removes weaponization dangers, because no uranium exists in solid form and the reactor runs continuously, with no shutdown for refuelling—all thorium and fissile uranium is consumed and any undesired gases and uranium/plutonium isotopes are flushed out as gases (e.g., as uranium hexafluoride) as the hot, liquid salt is pumped around the reactor/exchanger system.

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I hide the text, because it was over estimating the role of thorium in energy production. In fact thorium is not used as nuclear fuel for commercial energy production. --Stone (talk) 18:22, 13 February 2011 (UTC)

Addition to "Key benefits"

--Tkreh (talk) 22:18, 12 January 2011 (UTC) I would like to propose the addition of the following to the "Key benefits" section.

The technological challenges in creating a nuclear explosive device from uranium-233 are about the same as those for creating a device from plutonium-239. However, a key difference between the two is that uranium-232 is always co-present with uranium-233 while plutonium-239 has no such contamination. This is important because uranium-232 is an intense gamma radiation producer that makes uranium-233 more difficult to handle than Plutonium-239 and explosive devices created from uranium-233 easy to detected because of the radiation.

Er. The article is on thorium, not uranium or plutonium. 22:11, 12 January 2011 (UTC)

Thorium v Uranium

Can someone explain the claim in the text (attributed to Rubbia) that a tonne of Thorium produces as much energy as 200 tonnes of Uranium? Thorium has a longer half-life than Uranium, so doesn't that mean it emits less energy in a given time? I'm not a physicist, so I'm not saying the text is wrong, but I think it should be explained. Does Thorium emit higher energy particles, or what?81.151.7.234 (talk) 12:11, 13 February 2011 (UTC)

He talks about the use in nuclear fuel (neutron induced fission) not about the spontaneous decay via alpha particle emission. Here the calculation of the energy content in a multiple cycle of breeding, burning and fuel reprocessing is not possible before the process is established. He simply estimates that and publishes it to advertise thorium as nuclear fuel. --18:22, 13 February 2011 (UTC)

Two questionable quotes

Two quotes in this article caught my eye. I would not think about removing them from the article given my lack of expertise, especially since I have no idea where to look for sources that would discount them, but hopefully someone else can review them. Keep up the good work here - thorium reactors sound like a great new direction for power generation. I just think we have to stop over selling everything.

The following quote is very suspicious: "With a thorium nuclear reactor, Dean stresses a number of added benefits: there is no possibility of a meltdown, it generates power inexpensively, it does not produce weapons-grade by-products ...". This quote is from the article "New age nuclear" in Cosmos Magazine, which hardly seems the most reliable source. Specifically, regarding there being no possibility of meltdown, the thorium fuel cycle does produce short lived nuclear isotopes in approximately the same magnitudes as existing fuel cycles. My understanding is that a main cause of reactor meltdown is that these short lived isotopes, outside of the primary fuel cycle isotopes such as thorium and uranium, produce radioactive energy which must be removed even if the reactor is shut down. My understanding is also that some Gen IV reactor designs are inherently stable, and will shut down if they overheat, avoiding some of the scenarios for meltdown. However, if they contain significant power producing radionucleides, they would still be susceptible to post-shutdown meltdown if there is a cooling loss as these radionucleides decay, so using thorium does not remove this problem. The source article seems to confuse "meltdown" with an uncontrolled chain reaction. In addition, it seems questionable to say that thorium reactors will produce power inexpensively, given that the reactor itself contributes significantly to the power production price and the price for a full-scale commercial thorium reactor is currently just a guess. Finally, a thorium reactor does produce weapons grade by-products. Some believe the U233 by-product is not as much of a proliferation problem as plutonium because it is harder to handle, but it could still be used as nuclear weapons material. The possible proliferation aspect has been stated as the reason the U.S. quit developing thorium decades ago. Perhaps this article should have a section analyzing all of these popular beliefs.

Also, could someone check the following quote. "Rubbia states that a tonne of thorium can produce as much energy as 200 tonnes of uranium" This quote is well sourced; by a CERN researcher quoted in The Telegraph (UK). However, I think it is inaccurate. The reason is that fission of thorium requires some form of breeding since the naturally accuring isotope of thorium is not fissile. A typical path is to breed thorium to produce U233, then fission of the U233 is performed, providing the neutrons for the breeding. The reason the quote is not accurate is that it seems to compare the energy produced by a ton of thorium, involving the required breeding, versus a ton of mined uranium without breeding. Uranium could also be used in a uranium breeder reactor to achieve much greater utilization of the normally unused uranium isotopes. I would think a more accurate comparison would compare the thorium energy with the uranium energy in the same type of reactor. Perhaps a thorium expert could find a source which does the accurate apples-to-apples comparison? —Preceding unsigned comment added by 69.231.146.23 (talk) 06:50, 15 March 2011 (UTC)

This source might be helpful: Bulletin of the Atomic Scientists, Sept/Oct. 1997. It's also worth considering whether the "economics" of existing reactors should begin to include potential "side effects." --Wikiwatcher1 (talk) 04:43, 19 March 2011 (UTC)

Good point. In the U.S. the government effectively covers the cost of the nuclear industries "side effects" risk instead of them having sufficient insurance for any accident. Requiring such insurance would certainly change the economics! —Preceding unsigned comment added by 69.231.146.23 (talk) 05:52, 20 March 2011 (UTC)

Not really. Price–Anderson requires the U.S. nuclear industry to have insurance for the first $12 billion per incident. A high-end estimate of the risk beyond that is $237 million per year; divide that by the 800 TW·h produced per year — it's a fraction of a cent per kW·h.

—WWoods (talk) 23:12, 22 March 2011 (UTC)

I meant any accident, like a serious melt down. Just checked the latest in Price–Anderson, the current insurance limit is $375 million, which would cover TMI but not any accident. The $12 billion is not insurance by the normal definition, nobody is paying premiums for it. Perhaps such premiums on an annual bottom-line basis would encourage development of safer (thorium?) reactors, I don't know. Looking for some "economics" way to encourage development of safer reactors, is all.

— Preceding unsigned comment added by 69.231.146.23 (talk) 09:05, 24 March 2011 (UTC)

• "there is no possibility of a meltdown" is in the context of a molten salt reactor. Meltdown is not a possible type of failure because the fuel is already a liquid as its normal state. If thorium were used as solid fuel in a LWR, then yes, a meltdown would be possible.
• "it generates power inexpensively" There are good reasons to think an MSR would be cheaper than LWRs: the core fluid is well below its boiling point so it doesn't need a reactor vessel capable of withstanding 75 or 150 atm of pressure, or such a large containment building. Operating at a higher temperature and thus higher efficiency, it needs less coolant per unit of useful power. The fuel is very cheap and doesn't need enrichment or fabrication into fuel elements.
• "it does not produce weapons-grade by-products" It's harder to get weapons-grade material from a power reactor than from the established methods of enriching natural uranium-235 or briefly exposing U-238 to neutrons and then chemically separating the resulting Pu-239. Particularly in a breeder reactor, where diverting too much of the fissile material produced would deprive the reactor of the fuel it needs to continue operating.
• "a tonne of thorium can produce as much energy as 200 tonnes of uranium" This is a comparison of a thorium breeder to a conventional uranium burner. A uranium breeder would achieve comparable fuel efficiency, but that takes a fast-neutron reactor, which is generally considered more challenging than a thermal-neutron reactor.
• "The possible proliferation aspect has been stated as the reason the U.S. quit developing thorium decades ago." The claim I've seen is that the lack of weapons potential is the reason for the lack of interest in thorium. The soft version is that, having developed the experience in working with uranium and plutonium as a result of the weapons programs, the U.S. didn't feel the need to develop a third nuclear technology.

—WWoods (talk) 23:12, 22 March 2011 (UTC)

• "there is no possibility of a meltdown" Thought meltdown meant the containment melted, not the fuel. A reactor could be designed to reduce likelihood of meltdown, e.g. inherently stable MSR with fission by-products continuously removed, but couldn't this also be done with uranium? Why say this regarding thorium, especially when it is not correct in general for a thorium reactor?
• "it generates power inexpensively" There are good reasons ... Absolutely! Hope this potential comes about.
• "it does not produce weapons-grade by-products" It's harder to get weapons-grade material ... Absolutely! Especially when most of the material is inseparable from highly radioactive U232. Seems there still might be proliferation concerns though.
• "a tonne of thorium can produce as much energy as 200 tonnes of uranium" ... generally considered more challenging ... but is it true that much more total energy is available?
• "The possible proliferation aspect ..." Wish I could remember where I read that. I'm aware of the lack of weapons potential issue also- that's in a wiki article somewhere. Could both be true?

In any case, I probably shouldn't be debating the merits of thorium in an article talk page, when the point is to figure out how to improve the article. Especially with people who probably know the material much better than I. The quotes just caught my eye as not being entirely accurate. I have been looking for sources in the last few days to challenge them, especially "no possibility of a meltdown", to back up any content changes, but am not really expert enough to know where to look.

— Preceding unsigned comment added by 69.231.146.23 (talk) 09:05, 24 March 2011 (UTC)

• "Meltdown" does refer specifically to the core elements, I think (when it's not being used as a metaphor), so it's not really the right term for an accident in an MSR. In fact, the way generally proposed to do an emergency shut-down is to pull the plug, and let the fuel drain out of the reactor into a holding tank! IIRC, the MSRE did have some trouble with corrosion-caused leaks -- they found little dribbles of fluoride salt which had frozen on the outside of the reactor.
• MSRs do run on fissile uranium, even if it starts as fertile thorium. Molten fluoride reactors and thorium are particularly well-matched, since processing the molten salt avoids the need to enrich uranium (as would be needed to run on U-235), and keeps thorium atoms from capturing a second neutron to become U-234 (as would often happen in a solid-fuel reactor).
• Uranium, plutonium, thorium, (and, I guess, any actinide) all release about 200 MeV per atom that fissions. Most of that "200 tonnes of uranium" is discarded as depleted uranium; 'spent fuel' is only ~25 tonnes per GWe-year, almost all of which is still uranium.

—WWoods (talk) 20:59, 25 March 2011 (UTC)

Problems with the article

All the thorium fuel cycle part of the article reads like an advert from a nuclear reactor industries.

• Proliferation issue is only right for pure thorium, but this is also right for heavy water reactors natural uranium (you see what India made from it). After the first cycle you have the same problem with U-233 as you have with Pu-239.
• Reprocessing is complicated due to the strong radiation from the thorium fuel.
• What Nobel laureate Carlo Rubbia (not a reactor expert) at CERN said is a personal observation and most likely not applicable as source of information. A book or peer reviewed paper would be better. (Nobody would make linus pauling a reference for vitamin C use)
• Alvin Radkowsky and the whole rest are advocates for their own company and should not be quoted for benefits. His naval reactor activities are irrelevant.
• Why is Israel mentioned in the benefits section?
• Tim Dean interview on a web page and Ambrose Evans-Pritchard, of the British Daily Telegraph seem really the very best sources for reliable information on the subject.
• The Turkish specialists book needs a closer look
• Thorium Energy Alliance is for sure not quotable as source for information.
• thorium produces one to two orders of magnitude less long-lived transuranics this is uncited and sounds like very dependent on the reactor and cycle used.

thorium energy projects

• Kakrapar-1 reactor the 500kg it uses is neglect able to the full load of several tonnes of uranium
• 30% of its electricity demand through thorium-based reactors by 2050 right from the crystal ball
• Norway was debating it was debated with what outcome? This is crystal ball at its best

All the mentioned energy projects are either research reactors, small additions of thorium to the uranium fuel or projections into the distant future. This is not an energy project.

--Stone (talk) 19:55, 19 March 2011 (UTC)

It's a balance to keep an article like this useful to both an average and expert reader. But at least the experts will know where to get peer-reviewed sources and will ignore the general interest material, or at least rephrase and expand it when necessary. --Wikiwatcher1 (talk) 21:37, 19 March 2011 (UTC)

I have no problem with having two references for every claim, but a personal interview is for sure not what I would like to have as source for whole sections of the article. One interview and one book or peer reviewed journal for all the claims that thorium is that good.--Stone (talk) 21:54, 19 March 2011 (UTC)

I agree with Stone, that too much prose exists in this article about the largely-unrealized use as a nuclear fuel and the tone of that prose is more rosy than the facts bare. But I prefer an evolutionary approach at first; adding better sourced text, adding better sources to existing text and copyediting per the better sources before moving any text to a more appropriate place. That is what I've started to do. I'm slow though due to limited time, so this will take a while. :) --mav (reviews needed) 22:53, 21 May 2011 (UTC)

Thanks Mav. This article needs a lot improvement. I will try to help where I can.--Stone (talk) 07:33, 22 May 2011 (UTC)

Anon above presents some harsh but I think accurate points about the pro-POV in this article. I will therefore start to comment out some of the worst prose and ce some of the other text. The prose will still be there, to give it a chance of being improved as we consult better sources, but I think it is past time to hide much of the POV from readers in the meantime. --mav (reviews needed) 00:30, 10 June 2011 (UTC)

I hide several hundred for the worst POV/badly-sourced words in the ==Thorium as a nuclear fuel== section. That section is still over twice as long as it should be per WP:UNDUE; any good detail should be moved and a summary left here per WP:SS. The overall tone of quoting expert after expert really bugs the hell out of me, especially when cited to Cosmo magazine and the Telegraph. That really isn't appropriate for an encyclopedia article. --mav (reviews needed) 01:03, 10 June 2011 (UTC)

Error

This Wikipedia page repeats a very common error about natural thorium, i.e. that it consists of only one isotope Th-232. This isn't true, though many sources say this. Natural thorium always contains significant amounts of Th-228 (in a radiological sense), its indirect decay product, in the same way that natural uranium always contains U-234, the indirect decay product of U-238. —Preceding unsigned comment added by Careysub (talk • contribs) 21:36, 17 October 2007 (UTC)

Correction: The article means that ²³²Th is the only primordial isotope. --3.14159265358pi (talk) 22:15, 5 December 2011 (UTC)

Another error:

The liquid range of thorium is large, but it is not the largest of any element. In the wikipedia article for Uranium, it states that that metal melts at 1405 and boils at 4404, a liquid range of 2999 degrees. This is comfortably higher than the claimed range for thorium. Please fix this factual error. 63.239.69.1 (talk) 19:29, 31 October 2008 (UTC)

Possibly a typo. --3.14159265358pi (talk) 22:15, 5 December 2011 (UTC)

Removed text

I removed this section: "Thorium metal has the treacherous property that although it can be safely handled (even with bare hands!) when newly purified, after just a few weeks it becomes sufficiently contaminated with decay products that this would be extremely hazardous. Even highly skilled radiation workers accustomed to handling other nuclear fuels such as uranium and plutonium have been caught by this."

I don't see how this can be true. The half-life of thorium is 14 billion years and the half-life of of its first daughter is 5.8 years. According to the EPA it takes 7 half-lives of the daughter isotope to reach equilibrium, which is 40 years at which point radiation would be only 9 times greater than the original "safe" dose". Or have I miscalculated? It been a while... Rmhermen 20:34 Mar 17, 2003 (UTC)

The claim came from first-hand stories from people who had actually been caught and contaminated, and probably would prefer not to be quoted. I wasn't really sure whether to put it in. But it's accurate and I think it's interesting.

I think the main problem with your calculations is that they assume that the danger is direct radiation. In fact the main danger is surface contamination and subsequent ingestion. Some of the daughters are a lot more mobile than the original thorium.

I haven't done the calculations myself or even looked up the details of the chain. But do your calculations take into account the different energies of the various decays? That's very important too.

With a chain like this, where the first decay is by far the slowest, as equilibrium is approached the number of decays per second of each stage becomes roughly equal. (Yes, I know we're still a long way from equilibrium, stay with me!) However, the radiation from some stages is a lot more dangerous than from others. (In fact the shorter half-lives tend to indicate more energetic decay and more dangerous radiation. Not always, for example Radium 222 in the Uranium series is quite nasty.) This effect will be important long before equilibrium is reached.

Comments? Would you like to have a go at rephrasing it, or do you still think it doesn't belong in? Andrewa 00:45 Mar 18, 2003 (UTC)

Correction:Radon, not radium.--3.14159265358pi (talk) 22:20, 5 December 2011 (UTC)

Moving on...

In that there's been no reply to this, I'm going to have a go at rephrasing and reinserting this text. It's accurate, and highlights very well the surprising complexities of radioactive contamination. Andrewa 18:15, 4 February 2006 (UTC)

Surface contamination by what? With such a long half-life, I don't see how there could be much contamination by anything that decayed from thorium. If the dispute is between math and unattributed anecdotes, I know which I prefer to rely on. — Preceding unsigned comment added by 24.74.142.252 (talk) 13:30, 6 August 2011 (UTC)

I think you might as well put the removed text back, or something similar to it. Natural thorium has (nearly) equilibrium concentrations of Th-228 in it. If you run the Bateman equations for Th-232, Ra-228, Ac-228, Th-228 and Ra-224 assuming equilibrium Th-228 levels, you are within about 10% of equilibrium radiation levels in about 12 days. Levels slowly drop off as it takes a while for the 5.75 year Ra-228 to build up. There is a minimum in activity at about 8 years (down to about 1/3 of equilibrium values), and then it builds up again on the growth of Ra-228. Does solving the Bateman equations for given initial conditions constitute original research?Fortran (talk) 02:44, 10 January 2012 (UTC)

---

Removed: "The thorium decay chain ends with an isotope of lead (²⁰⁸Pb), but passes through an isotope of radon (²²⁰Rn) (also called "thoron")[4]. Radon gas is a radiation hazard. Good ventilation of areas where thorium is stored or handled is therefore essential."

In equilibrium there is only about 1 micro gram of radon present for every 200 tons of thorium. At a half life of only 55 seconds it doesn't even have time time to seep out of the thorium matrix and reach anyones lung. This is simply not a hazard.

Another way to look at the short half life of Rn-220. Rn-220 radon cannot travel anywhere near as far as the 3.8235 day Rn-222 can travel. Essentially the Rn-220 that can escape a mass is derived solely from Ra-224 that is on the surface. However, having three 6+ MeV and one 9 MeV alphas, a 2.2 MeV beta and a 5 MeV beta still to come after the Rn-220 has possibly moved elsewhere as a noble gas is a concern. A complicating factor is the 10.64 hour Pb-212, which metabolism might do something with.Fortran (talk) 02:44, 10 January 2012 (UTC)

Thorium safety -- and mantle lamps?

Okay, so thorium decays into other radioactive elements and "is safe if not handled, but aerosolized thorium is hazardous".

In a mantle lamp, the thorium is intensely heated and there is a strong air updraft through the mantle mesh. It would seem this is a perfect opportunity for the thorium to become aerosolized. So are mantle lamps really safe in an enclosed space such as a house, or not?

DMahalko (talk) 16:29, 28 April 2008 (UTC)

The mention of radon is nonsensical. Following the link to wikipedia's "decay chain" article reveals that the isotope of radon produced has a half-life of only 55 seconds. The usual form of radon gas has a longer half-life and comes from uranium, according to wiki's radon article.

Also, given thorium's 14 billion year half-life, if thorium did decay into radon gas and you had two ounces of thorium, it would take the entire lifetime of the universe so far to get an ounce of radon. — Preceding unsigned comment added by 24.74.142.252 (talk) 13:22, 6 August 2011 (UTC)

I misread the decay chain, actually radon's half-life from thorium is 5.5 years. Given thorium's half-life I still think that having a piece of thorium in an enclosed room isn't dangerous, but large geological deposits of thorium can produce high radon levels, according to the book Power to Save the World by Cravens and Rhodes. — Preceding unsigned comment added by 66.194.29.253 (talk) 19:05, 7 November 2011 (UTC)

No, ²²⁰Rn's half-life 55.6 seconds. --3.14159265358pi (talk) 22:24, 5 December 2011 (UTC)

Camping Gaz now describe their mantles as "non radio active", which suggests that they've addressed the issue. --Redrose64 (talk) 11:43, 10 January 2012 (UTC)

Another Error

Thorium research was started before 1997. It at the very least, was onging by 1977 because in the book that was cited by whomever wrote this thing to begin with, on page 19, it says 1977, not 1997. Upper right hand side; they put a thorium core in a reactor. They were experimenting/researching thorium by then. So, I changed the date from 1997, which is definitely wrong, to 1977.

http://books.google.com/books?id=2wsAAAAAMBAJ&pg=PA19&dq=thorium+reactor&hl=en&ei=vy6ETbP5JJOCsQOD1Lj1AQ&sa=X&oi=book_result&ct=result&resnum=1&ved=0CCwQ6AEwAA#v=onepage&q&f=true

192.33.240.95 (talk) 16:02, 3 February 2012 (UTC)

The grant from that ref is 1997 though. Article should mention Shippingport's 3rd core which was breeding Thorium. -- Limulus (talk) 21:39, 3 February 2012 (UTC)

Section Needs Updating

This area references a reactor opening in 2011...it's 2012! — Preceding unsigned comment added by 24.68.224.144 (talk) 05:58, 10 February 2012 (UTC)

== Please Update Article ==

Please update this article with the latest information about Thorium... New developments have occurred since 2011. — Preceding unsigned comment added by Dyerx (talk • contribs) 20:24, 22 February 2012 (UTC)

Do you have anything specific in mind? Also, we would need a reference source for anything added, per the policy on verifiability. --Redrose64 (talk) 20:56, 22 February 2012 (UTC)

[5] ? --Stone (talk) 21:32, 22 February 2012 (UTC)

Update page on Nuclear Fuel?

Greetings, I see that there is very little mention of Thorium on the page for nuclear fuel. I am happy to help anyone edit information to be placed there; it also looks like this page needs to be edited as well. I will recruit for information source from the thorium advocacy groups...thanks! Joel J. Rane (talk) 18:08, 8 March 2012 (UTC)

Thorium advocacy groups are part of the problem. There is no running Thorium reactor and most of the uses as nuclear fuel are at best projects at worst some paper work of thorium advocacy groups. This is not suitable to take more than a small share of the whole article.--Stone (talk) 19:16, 8 March 2012 (UTC)

Thorium bomb?

I have removed the "Thorium Bomb" section just added by user Sigsmund:

Whilst Thorium is not fissile it can be detonated when subjected to external neutron flux and configured appropriately. The likely method is to explosively apply an external neutron flux or a plasma pinch, possibly by explosive compression of Lithium plasma against a shell of Deuterium, or Tritium around a core of Thorium.

Japanese nuclear physicist Prof Seitaro Koyama noted the detection of radioactive rain over Niigata on March 21st & 24th 1956, with Thorium 231 and Rubidium 86, but exhibiting no traces of Uranium or Plutonium. This was reported by the Pittsburgh Press - Apr 21, 1956. The test blast of another Soviet Thorium Bomb was reported on April 17, 1957.

The first part seems to be unreferenced speculation. The second part apparently references this article but there's no mention of Th-231 in it; I did find this one however that does; I am unable to find any follow-up reports that might verify Koyama's findings or conclusions. Don't think this should be added back in unless better refs are found. -- Limulus (talk) 18:40, 25 April 2012 (UTC)

There is also a mention of the possibility to use U233 generated from thorium in a bomb design slipped into the thorium energy fuel cycle section. This may be appropriate to discuss but this doesn't seem like the proper place for it, maybe it should go to the benefits and challenges section and be mentioned along with an indication of why some have said it might be proliferation resistant. Something to do with U232 contamination I understand although I'm not qualified to assess the validity of either claim. Phil (talk) 07:56, 10 July 2012 (UTC)

New general readership article: "Thorium-based nuclear power"

I feel that a more general article, easier for the average person to understand, would be useful. So I put together a draft version here (started as Thorium-based nuclear power) for review and comments. It's a rough draft so feel free to point out grammatical and technical errors, as I'm sure there are plenty, along with ideas for improvement.

The closest articles about thorium-based nuclear power seem to be Liquid fluoride thorium reactor and Thorium fuel cycle. However, both are very technical. The thorium article here covers the subject also, and I used many of the sources and text, but toned them down to a more "average reader" level by avoiding technical jargon. It's really more of an introduction, but has links to this and the other articles for the science minded.

If it seems ok, we'd be able to shorten the overlapping details from this article. I guess comments can go here.--Wikiwatcher1 (talk) 07:46, 10 July 2012 (UTC)

Dangers section

The dangers section is completely uncited, it seems like it deserves some references. Also the first sentence regarding powdered thorium igniting is repeated above in the article, it seems like it shouldn't need to be repeated although I'm not sure which place it is more appropriate. Looking at the other elements around it, most don't have dangers section. Actinium, Plutonium, and Proactinium have a Precautions section. This seems to indicate that is the guideline for organization of these articles http://en.wikipedia.org/wiki/Wikipedia:WikiProject_Elements/Guidelines Should this section be renamed and rewritten to match that format? Phil (talk) 07:46, 10 July 2012 (UTC)

I Agree Phil, so as per Wikipedia:Be bold, make the change man. Boundarylayer (talk) 14:11, 6 September 2012 (UTC)

New Development

I don't know if any one wants to add something on this but it just recently happened. Thorium uses to date stars in far-away galaxies using the same method as with carbon dating. I haven't got a source, though. It was on Google News.

— Preceding unsigned comment added by Lamarque (talk • contribs) 18:57, 2 June 2007‎ (UTC)

Lede contains a misleading double negative =

A sentence that caught my eye was- 'absence of non-fertile isotopes.'

I think this is a bit convoluted with the double negative, perhaps something like the most prevalent isotope is regarded as fertile.

As Thorium 228 isn't regarded as fertile, so the sentence, as it stand right now, is also a bit misleading.

Boundarylayer (talk) 14:11, 6 September 2012 (UTC)

Reserves estimate

This section is poorly worded and has confused terms. It is mixing up the terms "reserve" and "resource". These are not synonyms and have different meanings. It winds on about how figures are different from different sources etc, but this is due to whoever wrote this section's mis-understanding of resources and reserves. I'll fix this up at some point. Also I'll add in newer figures, as there have been figures published in 2009 I believe. --Afrotrance (talk) 02:33, 25 October 2012 (UTC)

just thought i point out that china estimates it own reserves to be at 300,000. this figure doesn't seem to be published outside of china. can we assume the international figure are also incomplete for many other countries? Akinkhoo (talk) 09:53, 20 December 2012 (UTC)

this source cited U.S has reserve of 915,000 tonnes. vein reserve considered as strategic reserve as well? http://www.mbendi.com/a_sndmsg/news_view.asp?I=98954&PG=15

China blazes trail for 'clean' nuclear power from thorium - article of interest today in the Telegraph. CarolMooreDC 05:21, 7 January 2013 (UTC)

Work Function property of Thorium missing

I'm surprised that this article leaves out the fact that thorium has an exceptionally low work function. This property is why thorium is added in TIG tungsten welding electrodes and some high-power vacuum tube filaments (among other applications) since it increases the electron emission. 67.210.53.39 (talk) 16:59, 1 April 2013 (UTC) Mike Waters

I have something to add.

Since I don't want to spark an edit war, I wanted to discuss on the talk page. You may have heard of Minecraft. If you have, you have probably heard of the Minecraft Mod called IC2. Well, the largest addon to the mod is Gregtech, and it adds Thorium Cells. You have to scroll down on this page to get to it and it'd be easiest to google to find an image of it, but here's a source: http://gregtech-addon.wikispaces.com/Reactor+Components — Preceding unsigned comment added by Pyotrveep (talk • contribs) 02:35, 11 May 2013 (UTC)

Note on thorium(II)

ThI₂ does not contain Th(II); it may be better to label it Th⁴⁺(I⁻)₂(e⁻)₂ for clarity. (Ref: Holleman & Wiberg, p. 1722. Double sharp (talk) 08:27, 17 October 2013 (UTC)

THOHR-ee-əm or THAW-ree-əm

I think the pronunciation is more like THAW-ree-əm than THOHR-ee-əm which has the vowel in "goat" according to Wikipedia:Pronunciation respelling key. Siuenti (talk) 16:00, 17 July 2013 (UTC)

It is not quite like either, but the former is closer to the IPA given. Changed. Double sharp (talk) 08:36, 17 October 2013 (UTC)

France

The World Almanac for 2007 list France as producing 100% of the United States' supply of Thorium. — Preceding unsigned comment added by 65.103.133.192 (talk) 12:44, 21 June 2013 (UTC)

That's probably because the US no longer mines its own Rare Earths, we buy it all from China (Mountain View mine closed because no longer a market for Europium for Color TV tubes.) Original mining of Thorium for Gas mantles, sort of disappeared with the buggy whip industry. Shjacks45 (talk) 01:19, 19 October 2013 (UTC)

Thorium's "intense" radioactivity

Thorium's exceedingly long half life coupled with the 56 second half life of Radon-220 (Rn-222 from Uranium is 3 day half life) make Uranium a very small risk. Would be a good comparison to contrast Thorium radioactivity to Potassium, Rubidium, Platinum, Carbon-14, Tritium, et al. And much of the World's Thorium is tied up in Granite which sequesters it well. The Thorium decay series reaches steady state after several hundred million years and initial processing of Thorium ores give tailings containing these intensely radioactive elements. Although there was EPA action over mine tailings, after the mines ceased separating Thorium they continued to process Phosphate Rock to fertilize Tobacco and other US crops. High radioactivity is not a characteristic of purified Thorium. Thorium and Uranium-238 are virtually undetectable by handheld Geiger Counters. (Rem ~6 counts per second for ubiquitous Cosmic Rays.)Shjacks45 (talk) 01:43, 19 October 2013 (UTC)

Thorium metallurgy

Thorium is a ferrophilic carbide former which has been alloyed with Iron to make hard tough alloys. Thorium also can nodularize Carbon in ductile cast iron like Cerium does. Probably worth a note that Thorium(+4) has a similar radius as Calcium(+2) and substitutes for Calcium in rock-forming minerals (e.g. in Feldspar of Granite, in "Phosphate Rock"/Apatite, in Flourite). Shjacks45 (talk) 04:09, 19 October 2013 (UTC)

What is the picture of Timothy Grass and gas mantle meant to prove?

A picture is shown in the "Dangers and biological roles" section that isn't referenced and no purpose for its inclusion is shown. Are we meant to infer from the picture that the radioactivity has no effect or an effect? — Preceding unsigned comment added by 188.31.215.232 (talk) 11:10, 13 December 2013 (UTC)

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Thorium as Automotive Fuel

Recently, I added two article citations to the section on "Existing Thorium Energy Projects". My edits were removed, and upon further thought, I agree with one of the removals:

Laser Power Systems, a Connecticut, USA based company, claims that it can have a thorium-based nuclear vehicle on the road by 2014. CEO Charles Stevens says that just one gram of thorium produces more energy than 28,000 litres of gasoline. Mr. Stevens says that creating a thorium laser using only 8 grams of thorium would power a small generator for the entire life of a vehicle.

This article, upon review, does not have a great deal of scientific backing to show that the project was actually produced or that thorium could support any of the claims of the company. However, I did include the following change:

Cadillac produced a concept vehicle in 2009 using thorium as its propulsion. The vehicle was called the Cadillac World Thorium Fuel Concept. The vehicle affectionately became known as "the WTF".

This particular project was verifiable and actually happened. Noting that there are no thorium-powered Cadillacs on the road today leads one to believe that the project was eventually scrapped, but the existence of the concept car is worth the reference in the section. Schlice (talk) 19:25, 29 April 2014 (UTC)

"Thorium, Not The Nuclear Savior Claimed"

"Thorium, Not The Nuclear Savior Claimed"

http://www.fukuleaks.org/web/?p=3101 — Preceding unsigned comment added by 99.190.133.143 (talk) 18:39, 12 May 2014 (UTC)

A far from neutral article, don't you think? --Pgreenfinch (talk) 20:56, 12 May 2014 (UTC)

Raises the issue of disposal of spent Thorium fuel and a number of other potential problems (terrorism, etc.), all absent from the main article. — Preceding unsigned comment added by 99.190.133.143 (talk) 23:16, 12 May 2014 (UTC)

Thorium as a liquid fuel

This article only has a brief section on using thorium as a liquid fuel. There is much research regarding this and is a very important piece to the discussion around using thorium as a nuclear fuel. Further explanation is needed in this section. Check out Flibe energy. Icecreamcooper (talk) 22:16, 9 June 2014 (UTC)

subarticle creation

Per comments at WP:ELEM, I took the section on Th reserve estimates and made it into the subarticle occurrence of thorium. The present "Occurrence" section, while still in the main article, also serves as the lede section of that subarticle now. Double sharp (talk) 14:38, 24 August 2014 (UTC)

Thorium's toxicological profile

[6] Double sharp (talk) 09:43, 27 August 2014 (UTC)

This notes further that the radiological hazard of Th must factor in the risk of ²³²Th and its daughter ²²⁸Ra. Double sharp (talk) 09:46, 27 August 2014 (UTC)

http://www.atsdr.cdc.gov/tfacts147.pdf and http://www.epa.gov/radiation/radionuclides/thorium.html Double sharp (talk) 15:32, 27 August 2014 (UTC)

OK, all incorporated into my sandbox at User:Double sharp/Thorium. Double sharp (talk) 15:36, 29 August 2014 (UTC)

GA Review

This review is transcluded from Talk:Thorium/GA1. The edit link for this section can be used to add comments to the review.

Reviewer: Parcly Taxel (talk · contribs) 03:54, 7 September 2014 (UTC)

Element 90, here we go. Parcly Taxel 03:54, 7 September 2014 (UTC)

GA review – see WP:WIAGA for criteria

1. Is it reasonably well written?

   A. Prose is "clear and concise", without copyvios, or spelling and grammar errors:

   B. MoS compliance for lead, layout, words to watch, fiction, and lists:

2. Is it factually accurate and verifiable?

   A. Has an appropriate reference section:

   B. Citation to reliable sources where necessary:

   C. No original research:

3. Is it broad in its coverage?

   A. Major aspects:

   B. Focused:

4. Is it neutral?

   Fair representation without bias:

5. Is it stable?

   No edit wars, etc:

6. Does it contain images to illustrate the topic?

   A. Images are tagged with their copyright status, and valid fair use rationales are provided for non-free content:

   B. Images are provided if possible and are relevant to the topic, and have suitable captions:

7. Overall:

   Pass or Fail:

1a

Again, bold text to be replaced by italic text.

Characteristics - Isotopes

• "However, in deep seawaters the isotope ²³⁰Th becomes more significant and hence , which led to IUPAC reclassified reclassifying thorium as a binuclidic element in 2013."

   Done Double sharp (talk) 06:12, 7 September 2014 (UTC)

  • I found the section on isotopes to be confusing. At one point thorium is called mononuclidic. The it is binuclidic. Then a few paragraphs down it is monoisotopic. Can we get rid of the "howevers" and settle on one classification?Delmlsfan (talk) 00:53, 15 September 2014 (UTC)
    • @Delmlsfan: Sorry for the late response – I didn't notice this message until just now, probably because I haven't been watching the review lately (it concluded before your comment)!
    • It's confusing (hence the long reply), and it doesn't help that the definitions of "mononuclidic" and "monoisotopic" vary from source to source. IUPAC's definition of "monoisotopic" is "[an element that] has one and only one isotope that is either stable or has a half-life greater than 1×10¹⁰ a" ([7], p.708). However: IUPAC has also used "mononuclidic" to mean the very same thing! ([8], p.2053). On Wikipedia we use "mononuclidic" for the latter, and "monoisotopic" instead means an element with only one stable isotope. So you could argue that we should always be using the "-nuclidic" terms here, for Th has no stable isotope (though it has an almost-stable one, ²³²Th).
    • The unfortunate thing is that that sentence is talking about natural Th, which is nearly pure ²³²Th. Since we are referring to Th, we should be using "isotope" since the atomic number is fixed at 90. So "mononuclidic" also doesn't feel right. Argh. Changed to "isotopically pure".
    • As for "binuclidic": well, IUPAC changed its classification of Th from mononuclidic to binuclidic in 2013, because in some specific contexts the concentration ²³⁰Th is not negligible. I suspect that in general you should still be able to find references to Th as a mononuclidic, simply because if you don't restrict your attention to those cases ²³⁰Th can be neglected along with the other transient natural Th isotopes (²²⁷Th, ²²⁸Th, ²³¹Th, and ²³⁴Th).
    • (In typing the above I notice that the article treats ²²⁹Th as a synthetic radioisotope, but the infobox treats it as a natural radioisotope. I've corrected the infobox according to the article, which is cited to a reliable source. I suspect the infobox was referring to Emsley's Nature's Building Blocks, but I'm not sure: if so the article's source – the Wickleder chapter – still seems more reliable.) Double sharp (talk) 14:26, 28 January 2015 (UTC)

Occurrence

• "It is a chemically unreactive phosphate mineral that has a high specific gravity and is found as yellow or brown monazite sand: ; its low reactivity makes it difficult to recover extract thorium from it."

   Done Double sharp (talk) 06:12, 7 September 2014 (UTC)

Production

• "…the rest of remaining rare-earth hydroxides remains remain in solution."

   Done Double sharp (talk) 06:12, 7 September 2014 (UTC)

Applications - Radiometric dating

• "Both of these dating methods assumes assume that the proportion of thorium-230 to thorium-232 is a constant during the time period, that the sediment layer was formed, and did not already contain thorium before contributions from the decay of uranium, and that the thorium cannot shift within the sediment layer."

   Done, in a way...your correction, while not changing the meaning of the sentence, wasn't actually what I meant, so I changed it to read "Both of these dating methods assume that the proportion of thorium-230 to thorium-232 is a constant during the time period when the sediment layer was formed, that the sediment did not already contain thorium before contributions from the decay of uranium, and that the thorium cannot shift within the sediment layer." Double sharp (talk) 06:12, 7 September 2014 (UTC)

Non-nuclear

• "This means that when heated to high temperatures, it does not melt, but merely glows with an intense blue light: addition . Addition of cerium dioxide gives a bright white light: ;[9] this property of thoria means that thoria and thorium nitrate are used in mantles of portable gas lights, including natural gas lamps, oil lamps and camping lights."

   Done (though not quite in the way you wrote). Double sharp (talk) 06:12, 7 September 2014 (UTC)

• "It has excellent optical transparency in the range of 0.35–12 µm, and its radiation is primarily due to alpha particles, which can be easily stopped by a thin cover layer of another material."

   Done Double sharp (talk) 06:12, 7 September 2014 (UTC)

6b (crosses somewhat into 6a)

• I am suspecting that the thorium bar image (the only non-free one in the article) isn't required, and then the monazite image from the previous section (which is free) can then be moved down. After all monazite is mentioned in the production section. Parcly Taxel 03:54, 7 September 2014 (UTC)

   Done Double sharp (talk) 06:14, 7 September 2014 (UTC)

Things to add

• The severe problems with the former thorium oxide using gas mntel producers in New Jersey leading to a EPA superfund site in 1996, although the company already closed in 1941.
• The Areva lead enterprise producing lead-212 from thorium decay chain for cancer therapy.
• The use of thorium-tungsten filaments in magnetrons used microwave ovens.

OK, I'll incorporate these. Not too sure about ²¹²Pb though, that's more lead than thorium. Maybe I could mention it as the ²³²Th chain being a great natural source of otherwise wholly artificial radioisotopes like ²¹²Pb. Double sharp (talk) 15:18, 2 September 2014 (UTC)

OK, I incorporated the discussion of ²¹²Pb, phrased in that way. Double sharp (talk) 11:25, 8 September 2014 (UTC)

Comments on Production and chemical

I have had a look at the production and chemical section.

Production- the greenwood reference quotes the reduction of ThO2 and ThCl4 (not the fluoride) with Ca

• Oxidation states- for TlH₂ its formal oxidation nstate as the compound is metallic (higher conductivity than the metal apparently) with electrons in a conduction band indicating a higher oxidation state than +2. TlS another metallic compound but would be another example of formal oxidation state of +2. The molecular species TlBr seems to be the only example of ox. state of +1 but its hardly a good example. The +3 state example is also dodgy as ThBr₃ does not appear to have been characterised.
  • Since they're not terribly good examples, I've changed it to just a simple mention that there are a few compounds where Th has a lower formal oxidation state. Double sharp (talk) 14:30, 28 January 2015 (UTC)
• Coordination numbers – The CN of Th⁴⁺ are high- it is a big cation-- this is a major feature of Th structural chemistry, some small mention of it. The nitrate pentahydrate was the first known example of 11 coordination found, see Greenwood p1276. The oxalate tetrahydrate is 10 coordinate. The Th(NO₃)₆ ^2- anion in the calcium and magnesium salts is 12 coordinate see Simon Cotton Lanthanide and actinide chemistry section 11.6.2
• Aqueous chemistry- There is no mention of redox potentials which indicate the unlikelihood of Th(III) compounds in aqueous solution. The actinide article says Th³⁺ solutions are blue (?) and quotes Greenwood, the paper NNG quotes was criticised later and the concensus now seems to be that Th³⁺ does not exist. Th⁴⁺ hydrolyses readily at > pH4 forming various polymeric forms, ultimately culminating in gelatinous hydroxide. All a bit murky with lots of conflicting data on the exact nature of the polymers. Yes hydrolysis isn't quite as ready as that of Fe³⁺, it is weaker but is real. Wickleder 119.
• Th⁴⁺ is a hard lewis acid (hard soft acid base theory) - favours hard ligands - e.g. O donors, complexes with S donors being less stable Simon Cotton Lanthanide and actinide chemistry section 11.4
• Th₄H₁₅ is only element with a known higher hydride. (i.e. higher than MH₃) ref Lester Morss doi 10.3286/tr.200901
• Organometallic- The wickleder chapter is very light on these compounds, as they are dealt with elsewhere in the book. See Simon Cotton's book for e.g. tetrabenzylthorium, Th(CH₂C₆H₅) ( known but structure has not been determined); the salt [Li(tmeda)]₃ [Th(CH₃)₇] and Th(CH₃)₄ adducts stabilised by phosphine ligands.

Axiosaurus (talk) 17:30, 3 October 2014 (UTC)

Thorium's viability as commercial nuclear fuel

Here's one more http://www.ne.anl.gov/pdfs/NuclearEnergyFAQ.pdf:

Why shouldn’t we use thorium reactor plants? Aren’t they safer than uranium-fueled reactors?

We may use the thorium cycle some day when uranium runs low, or in countries with little uranium. But uranium fuel technology (especially recycling) is much more developed than thorium technology and therefore more commercially viable. All of the arguments commonly made in favor of thorium reactors are also true for advanced uranium reactors, including the safety arguments, and uranium advanced reactors are far closer to commercialization than are reactors

using thorium technology, so there are no strong reasons to abandon uranium in favor of thorium.

86.127.138.234 (talk) 15:09, 28 January 2015 (UTC)

Added the source. Thank you! Double sharp (talk) 15:28, 28 January 2015 (UTC)

Thorium Space Ship Ausgestellt Hannover Messe Jahr 2015

Wer investiert in die Space Materialforschung bis zum Jahr 2020 50 Milliarden Dollar? Im Kern geht es darum Materialien zu entwickeln, auf der Erde, auf dem Mond, auf dem Mars, im Sonnensystem, welche geeignet sind im Sonnensystem zu existieren bei den dortigen realen wissenschaftlichen Bedingungen (Vakuum, Temperaturen um den absoluten Nullpunkt, Elektromagnetische Strahlung der Sonne und Sonnenwinde). Wie ist der derzeitige F&E-Stand der Wissenschaft und der Industrie/Handwerk (Hannover Messe 2015, April)? Haben die besten deutschen 1000 Unternehmen in diesen Bereich schon investiert und wie ist der Stand der produzierten Produkte? Auf der Hannover Messe April 2015 stellen die besten Deutschen Unternehmen jeweil ein von ihnen entwickeltes und produziertes Produkt vor. Zum Beispiel muss es Industrielacke (Airbus 380) geben die Temperaturen von minus 270 Grad Celsius enthalten und im Inneren eines Thorium Space Ship (Technischer praktischer Konstruktionsplan?) muss es Materialien geben die Temperaturen widerstehen bis zu 1 Million Grad Celsius Plus. Welche Materialien produzieren die Weltraumorganisationen NASA ESA und Russland, Indien, Japan, China? Statoil Airport Bergen Norway 143.97.213.134 (talk) 06:53, 30 January 2015 (UTC)

Tig Electrodes

I was surprised to see that the section on applications doesn't list thoriated tungsten TIG welding electrodes. I am not a welder so I think it would be best if someone who knows more about this could add information about this application. --Sbreheny (talk) 16:40, 25 March 2015 (UTC)

Hmm. It's in the lede ("Thorium is also used as an alloying element in nonconsumable TIG welding electrodes."), but strangely not in the applications section. I'll go check where I found this, and try to cobble together something soon. Double sharp (talk) 14:28, 28 March 2015 (UTC)

Hmm, was added in a big edit by Double sharp last summer.--Stone (talk) 15:56, 29 March 2015 (UTC)

Oh dear, that summer? The summer when my computer started selecting random things and deleting them accidentally? (I managed to break the table at list of nuclides accidentally like that! I fixed the page and got that computer problem fixed once I noticed, of course.) If so, this is definitely my fault: thanks to Stone for replacing it. Double sharp (talk) 15:59, 29 March 2015 (UTC)

No problem. Your edit was a good improvment. --Stone (talk) 16:08, 29 March 2015 (UTC)

Occurrence

This section contains the clause "thorium-232 is several hundred times more abundant than uranium-235", which is of dubious relevance, and may be misleading. Uranium-238 is about a hundred and forty times more abundant than uranium-235, but the latter has a property that is not found in U-238 nor Th-232. It is thermally fissile. Th-232 can be transmuted into fissile U-233, by a process that may be simpler or safer than fast neutron irradiation of U-238, but the source of the neutrons for startup is likely to be either U-235 or Pu-239. DaveyHume (talk) 17:53, 12 May 2015 (UTC)

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Tens of billions of years

If the universe is less than 14 billion years old, how can Th and U have been produced tens of billions of years ago?--Klausok (talk) 17:29, 10 July 2016 (UTC)

I messed up; I just meant around ten billion years. Changed. Double sharp (talk) 08:23, 14 July 2016 (UTC)

Early 19th century

https://books.google.ru/books?id=yb9xTj72vNAC&pg=PA310&dq=thorium+history&hl=en&sa=X&ved=0ahUKEwizleOsxO7NAhXHDiwKHaRVDvQQ6AEIGzAA#v=onepage&q=thorium%20history&f=false this says that the actual thorium mineral was found as early as 1819

This book is rather noted for being so chock-full of errors that I wouldn't trust it; so I would keep the current date. Double sharp (talk) 08:25, 14 July 2016 (UTC)

https://books.google.ru/books?id=9vPuV3A0UGUC&pg=PA52&dq=thorium+hist+Berzelius&hl=en&sa=X&ved=0ahUKEwiL-taExe7NAhUH3SwKHbYnD54Q6AEIJzAB#v=onepage&q=thorium%20hist%20Berzelius&f=false but, according to this, Berzelius got it only in 1928 (believable if we assume they didn't know each other). Also lists uses that were found for Th after 1885

OK, I have this (it's the Wickleder chapter), and while I used it for much of the applications section I can and will write a brief summary up here too. Double sharp (talk) 08:40, 14 July 2016 (UTC)

https://books.google.ru/books?id=k8D9BAAAQBAJ&pg=PA1&dq=thorium+hist+Berzelius&hl=en&sa=X&ved=0ahUKEwi-ou_Cxe7NAhXLKCwKHajaDOcQ6AEIRTAH#v=onepage&q=thorium%20hist%20Berzelius&f=false the name dates back to 1817

Added. Double sharp (talk) 08:40, 14 July 2016 (UTC)

These are cool details and I'd love to have them in, but to my dissatisfaction, I can't find out what techniques Berzelius used on a quick look. Apparently I'll have to search for the papers he published.--R8R (talk) 18:29, 12 July 2016 (UTC)

https://books.google.ru/books?id=tfM0HWCAT3EC&pg=PA475&dq=berzelius+thorium+1815&hl=en&sa=X&ved=0ahUKEwiYqLDO7e7NAhVsGZoKHU1eCbQQ6AEIbzAN#v=onepage&q=berzelius%20thorium%201815&f=false -- just take a look. He not only thought there could be a new metal, he though the mineral was an oxide of that metal and he even named the earth as "thorina"; also we learn he experimented with gadolinite when he found it. The source also describes first studies on Th, maybe there's something you find worthy (for example, Berzelius's atomic weight of Th was apparently nowhere near 232 (7.5*16=120), also it was him who started the idea of Th being divalent)

See, this is why this whole thing is murky: there is the xenotime story, that everyone parrots, and then there is also this thing about gadolinite now. I can believe that he thought it was in both minerals, but this is really encroaching on interpreting the sources to one's convenience. (This is where we really need Berzelius' papers.) Double sharp (talk) 08:40, 14 July 2016 (UTC)

Nothing really murky for me, I have a coherent picture of what happened, correct me if I'm missing something: B was studying a gadolinite sample and found a white mineral impurity, which he assumed was an earth of another new element. No source says gadolinite had this thorium on it. That impurity, howe, turned out to be xenotime.--R8R (talk) 08:57, 14 July 2016 (UTC)

http://ntl.inrne.bas.bg/workshop/2011/proceedings/apostolova.pdf -- also see this: "In 1815 Berzelius observed thermoluminescence in gadolinite caused by the α-decay of U and Th traces [7]." that [7] actually reveals the original 1815 paper; unfortunately, I can't find it online (also, it's apparently in Swedish, but we could ask a Swede for help if we had the paper to work with; anyway, I got some info already)--R8R (talk) 21:50, 12 July 2016 (UTC)

Not early 19th century, but here's minor detail missing: the German physicist discovered Th's radioactivity before Curie did: "Thorium was discovered to be radioactive by Gerhard Schmidt in 1898 – the first element after uranium to be identified as such. Marie Curie also found this, independently, later in the same year. (3)" http://www.chemicool.com/elements/thorium.html --R8R (talk) 21:59, 12 July 2016 (UTC)

Read on Berzelius's analysis techniques here: https://books.google.ru/books?id=wbybAAAAQBAJ&pg=PA156&lpg=PA156&dq=quantitative+mineral+analysis+berzelius+thorium+1828&source=bl&ots=juGvDObvZv&sig=4-0PjP2SPfXSjIhBpBt22tjePV0&hl=en&sa=X&ved=0ahUKEwiB-O-A9-7NAhUqEJoKHQGmC7gQ6AEILDAD#v=onepage&q=quantatively&f=false

I hope these links satiate your need for more info on early 19th century?--R8R (talk) 22:08, 12 July 2016 (UTC)

3 periodic tables

We don't need three period tables in this article. At the bottom there already was Template:Periodic_table_(32_columns,_compact) but template:PeriodicTable-ImageMap was just added by User:Drbogdan. So one of these two should be cut. Graeme Bartlett (talk) 23:08, 2 December 2016 (UTC)

@Graeme Bartlett: Thank you for your comments - yes - the newly created "{{PeriodicTable-ImageMap}}", an "interactive image map" updated to include the latest officially named elements, was added to the chemical element articles - this version seems to be in the more familiar "Periodic Table" form and, as such, may be more accessible and useful to the average reader - after all => "Readability of Wikipedia Articles" (BEST? => Score of 60/"9th grade/14yo" level) - (also - somewhat related discussions at => "Template talk:Nature timeline#BestWording" and "Template talk:Life timeline#Class Aves as a subset of Dinosaur?") - Comments Welcome from other editors of course - in any case - Enjoy! :) Drbogdan (talk) 00:58, 3 December 2016 (UTC)

References

Thorium in nukes

While I haven't yet found any historical attempts by anyone to create nukes from thorium, it turns out this could be done, according to heavily referenced Dr. Gordon Edwards (whose name can be googled to get many interesting results).

Also, a very interesting link: http://liquidfluoridethoriumreactor.glerner.com/2012-worthless-for-nuclear-weapons/ (the comments are also gold)

According to this one, the U.S. also tested some U-233-based weapons; see report

!!! World Nuclear Association: "Weapons and non-proliferationThe thorium fuel cycle is sometimes promoted as having excellent non-proliferation credentials. This is true, but some history and physics bears noting.The USA produced about 2 tonnes of U-233 from thorium during the ‘Cold War’, at various levels of chemical and isotopic purity, in plutonium production reactors. It is possible to use U-233 in a nuclear weapon, and in 1955 the USA detonated a device with a plutonium-U-233 composite pit, in Operation Teapot. The explosive yield was less than anticipated, at 22 kilotons. In 1998 India detonated a very small device based on U-233 called Shakti V. However, the production of U-233 inevitably also yields U-232 which is a strong gamma-emitter, as are some decay products such as thallium-208 ('thorium C'), making the material extremely difficult to handle and also easy to detect.U-233 classified by IAEA in same category as high enriched uranium (HEU), with a significant quantity in terms of safeguards defined as 8 kg, compared with 32 kg for HEU."

I think that settles it.--R8R (talk) 13:10, 5 June 2017 (UTC)

Thorianite

"Thorianite with 12% ThO2" is not thorianite, but either uraninite or cerianite-(Ce). The 50-50 rule is here applicable, and the lowest possible content of ThO2 in thorianite is 50%.Eudialytos (talk) 23:34, 8 June 2017 (UTC)

The different names are given in the note. I have removed the statement about "usually 12%", because as you note it is then not called thorianite. Double sharp (talk) 15:28, 15 June 2017 (UTC)

General comments

• TOC now is:

1 Bulk properties
2 Isotopes
3 Chemistry
4 Occurrence
5 History
6 Production
7 Modern applications

Maybe more like: (from zinc, FA / OK, #. Chemistry is missing; not a very good example?)

1 Characteristics
1.1 Physical properties
1.2 Occurrence
1.3 Isotopes
2 Compounds and chemistry
3 History
4 Production
5 Applications

-DePiep (talk) 20:54, 26 July 2017 (UTC)

• From the main infobox I removed 4/5 trace isotopes. They were reinstalled for 'all are mentioned in the text'. However. I propose we add the more complete {{Infobox thorium isotopes}} to the section Isotopes. Then remove the lesser relevant ones from main infobox, leaving ~3 there. -DePiep (talk) 21:03, 26 July 2017 (UTC)

Occurrence is okay as a standalone section (see fluorine and lead, both FAs, both promoted more recently than zinc). Isotopes is a separate section here by exception rather than by rule (this is a particularly hot topic for an element like thorium). That's why it is the way it is.

Good idea about the isobox, though. I like it.--R8R (talk) 21:32, 26 July 2017 (UTC)

Hardness

The article on plutonium says plutonium "...is about as hard and brittle as gray cast iron..."; If according to this thorium article thorium hardness is "...similar to that of soft steel...", how can that be, because cast iron is much harder than soft steel. 2602:30A:2CFC:B1A0:B4D9:1786:6F8F:F78B (talk) 04:09, 22 October 2017 (UTC)

Yes; so thus plutonium is harder than thorium. I don't quite understand, what is the confusion?--R8R (talk) 09:57, 22 October 2017 (UTC)

The statement in the Th article "Thorium is nearly half as dense as uranium and plutonium, but is harder than either of them" is cited (to Tretyakov); while I can see the statement about the hardness and brittleness of Pu in its article, the source it is cited to does not contain this assertion. (Though maybe I should have expected this, for such an old FA.) Double sharp (talk) 14:31, 22 October 2017 (UTC)

The change was put into the text [9] in Septemper 2014.--Stone (talk) 15:12, 22 October 2017 (UTC)

Yes, I added it to the Th article; IIRC I got it from Tretyakov, or indirectly from the actinide article. Double sharp (talk) 15:14, 24 November 2017 (UTC)