Talk:Helium-3

Something isn't quite right

the two sentences: "Some of it leaks up through deep-sourced hotspot volcanoes such as those of the Hawaiian islands, but only 300 grams per year is emitted to the atmosphere. Mid-ocean ridges emit another 3 kilogram per year" lead me to believe that grams is a typo, and kg should be used. However, without citations (or any actual knowledge about volcano emissions), I don't want to just change this. Anyone know? —Preceding unsigned comment added by 67.244.35.95 (talk) 02:40, 11 November 2009 (UTC)

What is boojum?

Does anyone want to explain what boojum is? 24.91.43.225 17:35, 10 Jun 2005 (UTC)

Cornell University theoretical physicist David Mermin decided that "boojum" was the perfect name for a new phenomenon in low temperature physics. The story began in 1976, when Mermin was thinking about how so-called anisotropy lines would arrange themselves in a spherical droplet of superfluid helium-3, an unusual phase of matter attained by cooling the rare isotope of helium to near absolute zero. It turned out that a symmetrical pattern of lines, although geometrically simple, is not stable and collapses to form a new pattern. Mermin realized this new pattern could be called a boojum, since it can enable the otherwise stable flow of the superfluid to "softly and suddenly vanish away," just as Carroll described it in the final stanza of his poem, "The Hunting of the Snark," DV8 2XL 21:18, 25 November 2005 (UTC)

Why so rare on Earth's surface?

I was reading that Helium-3 is rare on the surface of the Earth and that its presence in geothermal springs is conclusive proof that the water was in contact with magma. Why is it so rare on the Earth's surface? Does it undergo a nuclear reaction or decay that renders it into something else over the lifetime of the Earth? -- Joseph Lorenzo Hall 20:48, 25 November 2005 (UTC)

Helium-3 gas consists of single very light atoms; if released at the Earth's surface, these helium-3 atoms tend to rapidly escape from the Earth's atmosphere. That's why–despite being the second most-common element in the universe–there's very little helium in our atmosphere. Unlike most other elements, helium-3 doesn't form chemical compounds, so there aren't even any processes available to bind or sequester helium-3 on the surface of the Earth.

Helium-3 is a stable isotope; it doesn't undergo a radioactive decay of any kind, and none is lost by that mechanism.

How the helium-3 gets to the magma in the first place is a question for the geologists. I suspect it may have been trapped when the earth first formed, either as He-3 or as its radioactive precursor, tritium. TenOfAllTrades(talk) 21:02, 25 November 2005 (UTC)

Ha! I distinctly remember doing the gravitational capture calculation in undergrad. astrophysics. Silly (old) me. -- Joseph Lorenzo Hall 04:57, 26 November 2005 (UTC)

If it is stable, what's the meaning of the box with a decay chain link? Jclerman 11:58, 3 February 2006 (UTC)

The decay chain is shown because Helium-3 is the end product of various decay chains. Ardric47 23:53, 6 May 2006 (UTC)

It may be worth pointing out here that He-3 atoms are somewhat faster than He-4 at the same temperature because they are lighter. Hence, they were harder to capture during Earth's formation phase. Deuar 20:08, 19 June 2006 (UTC)

I added more detail about terrestrial sources. Popular theories tend toward some He-3 being in the mantle, but it won't do us much good because we probably can not safely release it. It is often thought that He collected on stellar disk rock surfaces, particularly from the solar wind. There are various estimates of how much He got in the core, how much in the mantle, and in various layers. I only found one source for an interesting idea: In the stellar disk He-3 had a high probability of being converted to H-3 (tritium), and tritium, being Hydrogen, could dissolve in Fe (iron), with tritium decay later producing He-3 inside iron which was later involved in planet formation. (SEWilco 06:13, 27 August 2006 (UTC))

I read in popular mechanics that Earth's magnetic field pushes away solar helium-3, hence the lack of it on the Earth, but also that the moon has significantly more of it because of the lack of a strong magnetic field. Kniesten 21:54, 29 June 2007 (UTC)

Hey, Tritium, with a half-life of 10 years, decays into Helium 3. —Preceding unsigned comment added by Indecisive nerd (talk • contribs) 01:36, 14 August 2008 (UTC)

ISTR an article on how the Moon formation process drove off a bunch of Earth's Helium. I'll see if I can find that. He-4 is a much more common decay product that He-3 so Earth recreated a bunch of that. Hcobb (talk) 15:04, 24 November 2009 (UTC)

Alpha decay emits high-energy Helium-4 nuclei, that are slowed to room temperature by collisions with adjacent nuclei (cf. neutron temperature.) Helium-4 created deep underground cannot reach the Earth's surface to escape into space. No comparable Earth-based process can produce Helium-3 deep underground. —Preceding unsigned comment added by 87.113.5.225 (talk) 05:16, 5 February 2010 (UTC)

template box

See previous question. EXPLAIN MEANING OF each element in THIS TABLE OR DELETE IT. It should be clear how to construct such a table, from where to get the information, etc.

Jclerman 19:59, 11 April 2006 (UTC)

do you think it is wise to mine helium-3 from the moon knowing so little about its geology 143.53.5.73 13:16, 11 April 2007 (UTC) Alan Whitaker

• h3 is abundant in sufficient quantities near surface of the moon. on earth, mining would require drilling deeper than we've ever drilled before ... on a massive scale that could disrupt the tectonics of the planet. we know the moon a) has no tectonics and b) doesn't require deep drilling .... (in fact the soviet plan is to use bulldozers ... not drills (http://www.independent.co.uk/news/world/europe/russia-plans-to-put-a-mine-on-the-moon-to-help-boost-energy-supply-524710.html)) 69.134.54.59 (talk) 10:04, 2 June 2009 (UTC)

Cryogenics

Helium-3 is used in cryogenics to achieve temperatures as low as a few thousandths of a kelvin; it was discovered by the Australian nuclear physicist Mark Oliphant while based ...

This seems to be a strange statement, and looks pretty dubious the way it is written. Maybe it is dubious?

• Is it really used to achieve these temperatures? Wouldn't you just use some cooling process, without caring what isotope you had.
• Why would it be better than natural abundance Helium, which must be much, much cheaper.
• What was discovered by M. Oliphant? Helium-3, the cooling process, the temperatures?
• Was the discovery of He-3 made during a cryogenics experiment? Is that why it is mentioned in this section? That would be pretty weird - no-one did isotope studies of normal helium previously?

Deuar 20:17, 19 June 2006 (UTC)

Helium-3 is used in Pulse tube refrigerators, it does help to achieve lower temperatures. Danifornication (talk) 00:17, 29 January 2010 (UTC)

Helium-3 really is used to achieve lower temperatures - at low temperatures, helium-3 and helium-4 are very different substances (thanks to their low mass and quantum mechanics). So, for example, at one atmosphere, helium-4 boils at 4.2 K, helium-3 at around 3.2 K. If you pump on helium-4 to reduce the temperature, you can't get much below 1 K before the vapour pressure gets too low - helium-3 will get you to nearly 200 mK. To go lower still, you mix the two and can get to a few mK. Isotope separation in helium is really easy! AdamW (talk) 16:21, 19 January 2012 (UTC)

We were asked, above: "That would be pretty weird - no-one did isotope studies of normal helium previously?"

Someone might have looked for different isotopes of helium earlier (1914 - 1934 or so), using the very early mass spectrographs, BUT helium only has two isotopes, and helium-3 is very rare. Those early instruments were not exact - as we should expect (mass spectrometers) - and when they put helium into them, they couldn't even see anything about helium-3 at all. Everything looked like helium-4 until sometime in the latter 1930s.

The early mass spectrometers worked O.K. with elements that had different isotopes in ratios (by number of atoms) more like nine-to-one, five-to-one, or three-to-one. With those mass spectrometers, they could tell the difference between isotopes like these: neon-20 and neon-22; chlorine-35 and chlorine-37; lithium-6 and lithium-7; magnesium-24, magnesium-25, and magnesium-26, nickel-58 and nickel-60.
The ability of an instrument to tell the difference bewteen things that are close together has been called its resolution for over 200 years, but too bad, we have millions of yo-yos who want to misuse the word "resolution" now. It is unscientific, but they don't care.
98.67.163.16 (talk) 00:11, 23 July 2012 (UTC)

ppm

Don't link to confusing Parts per notation which can be understood as Parts "per notation" or "Parts per" notation. Jclerman 15:39, 24 June 2006 (UTC)

I don't understand. The point of the link is that you can click on it, and the article Parts per notation is not ambiguous. —Keenan Pepper 16:55, 24 June 2006 (UTC)

The article is fine. No problem. What I find confusing, ambiguous, is its title. (Yes, I'm not so smart, it took me a long time to understand that perhaps its meaning was not

• Parts per notation (as in ppn),

but perhaps the alternate

• Parts per notation (as in pp notation).

Then, I couldn't verify its meaning at the NIST either, where I looked for verification of ppn after I didn't find a parts per notation in their website. Jclerman 17:27, 24 June 2006 (UTC)

In that case, we should move the article to a different title, not remove links to it. Would Parts-per notation, with a dash, be better? —Keenan Pepper 17:33, 24 June 2006 (UTC)

Sure. I reverted the link because when mousing over the link I got a label I couldn't understand. The article could be renamed as you suggest, or as in the only mention I found at [1] as:

Table 3 shows the sequence in “parts per” notations to describe lower and lower concentrations

Also, note that notations (i.e. in plural) is more comprehensive of all the notations it applies to rather than notation (i.e. in sigular). Like used in the quoted title to the table. Jclerman 17:56, 24 June 2006 (UTC)

Common myth part needs to be clarified

"A common myth is that due to the rarity of helium-3 on Earth, any reliable sources of the fuel have to come from other bodies in space. This is untrue. Helium-3 is a byproduct of tritium decay, and tritium can be produced through neutron bombardment of lithium, boron, or nitrogen targets."

While that may be true, there certainly is a good reason why USA, Russia, and China want to go to the moon and extract the Helium 3 from there, instead of bombarding lithum, boron, or nitrogen with neutrons. This needs to be explained. Malamockq 13:54, 11 August 2006 (UTC)

Explained. (SEWilco 05:59, 27 August 2006 (UTC))

Unfortunately there is no evidence for an economic reason to go to the moon to get helium-3. Space enthusiasts in several countries created the myth of its rarity as a rationale for human spaceflight. ~~ — Preceding unsigned comment added by Danwoodard (talk • contribs) 14:58, 15 October 2011 (UTC)

Contradiction

From the 'Manufacturing' section:

"Commercial use of fusion reactors would require tens of tons of helium-3 each year to produce a fraction of the world's power."

From the 'Lunar supplies' section:

"Accordingly, helium-3 seems less likely than other reactants for use in fusion power generation"

I've amended the sentence from the manufacturing section to make it clear that helium-3 is only one of several possible fusion fuels by changing it to:

"If commercial fusion reactors were to use helium-3 as a fuel, they would require tens of tons of it each year to produce a fraction of the world's power."

I'm pretty sure this is the correct resolution of this contradiction.

Depth to source

SEWilco, please do not revert things just because I made the edit.

If you want to know why I edited it, it is because the statement "Geologists use how much this ratio is altered as a measure of depth of the source of the helium, with ratios above 200ppm expected to be in mantle material." is false. By reverting this edit you are merely showing that you do not understand the science of helium isotope geochemistry, nor about geology. Allow me to explain;

The ³He/³He ratio within the mantle is 8 Ra, 8 times the ratio of th atmosphere. ie; if you have 200-300ppm ³He in 1,000,000 parts of a sample o helium in the mantle, you have 25 ppm ³He in helium in the atmosphere. Correct?

So, how do we determine the depth, which is an absolute measurement, of a reservoir of helium which we sample, via seeing how the ratio alters? By the wording of what I edited, the indference is that as the ratio of the helium changes, a geologist can determine the depth from which this helium originated.

This is patently false. There is no rule to say that 1km from the surface all helium is found with a ratio of, say 35ppm ³He. That at 10km from the surface, helium reservoirs have a ratio of, say, 70 ppm ³He. This is absolutely and incontrovertibly false, and thus the sentence was removed.

In fact, within the crust, oceanic or otherwise, the ratio of ³He changes not with depth but with time, as alluded to correctly elsewhere within the article, via radioactive decay via alpha emitters.

In reality, the best science can do is determine the contribution of 'mantle helium' to a reservoir by observing concentrations of ³He in excess of atmospheric (ie, an Ra >1,) or by observing concentrations of ³He in deficiency of atmospheric. Most crustal reservoirs have a ³He/⁴He ratio of 0.01 or less.

So, please do not revert this again or I will have to seek arbitration, and I know how popular you are for your grudges.Rolinator 01:35, 30 September 2006 (UTC)

I edit the text, not the editor. I reverted your deletion of information, not you. Your latest expansion provides more detail which will be helpful. My earlier summary was awkward and at least needed rephrasing, including your clarification of the main article on the subject (which I had stub-created). (SEWilco 04:02, 30 September 2006 (UTC))

This is gonna save the world

NASA has been working on this for years and with this. --E-abulous 13:22, 23 May 2007 (UTC)E-abulous

NASA has no program for obtaining helium-3 from extraterrestrial sources. — Preceding unsigned comment added by Danwoodard (talk • contribs) 02:17, 10 June 2012 (UTC)

Do I detect Anti-Nuclear Fusion Sentiment?

The sections of this article require, perhaps, a more even handed critique. The article states that the Coloumb barrier for Helium-3 based nuclear reactions is higher than for the Deutrium-Tritium reaction. Does that necessarily imply that Helium-3 is not terribly useful as a fuel for nuclear fusion? Are there no novel ways of using Helium-3's properties to make nuclear fusion more economical (at the very least, the article could show some consideration of Helium-3 usefulness if at all possible). Anyhow, this particle of the article reads very well - so it is probably the case that Helium-3 isn't at all useful for nuclear fusion....

"The immense cost of reactors like ITER and NIF are largely due to their immense size, yet to scale up to higher plasma temperatures would require reactors far larger still."

I don't know of ITER's technical details - but is size one of the major factors for its expense? Or are there likely to be other issues that cause ITER to be so expensive? At the very least, this sentence could use an extra citation.

ConcernedScientist 22:30, 20 June 2007 (UTC)

I think that section is biased crap, ITER article says: "proposed costs for ITER are € 5 billion for the construction, maintenance and the research connected with it during its lifetime", not immense cost compared to nuclear power plants, for example Finland's new EPR nuclear power plant cost 3.7 billion €. 84.250.204.83 (talk) 21:31, 8 April 2008 (UTC)

Afaict the only advantage of the 3He based reactions is there avoidence of the high neutron flux (which is damaging to reactor componets among other things) but to make 3He on earth would require use of high neutron flux obtained from something as well as a lot of waiting time. Therefore the 3He based reactions are uninteresting until/unless we get a serious moonbase going. Plugwash 22:32, 19 July 2007 (UTC)

Aneutronic Fusion ?

The article currently says that side reactions cause the Helium-3 fusion to be dirty ("However, since both reactants need to be mixed together to fuse...") . However, neutron-producing reactions occur for the "First" and "Second" generation fuels. For the "Third" generation (pure Helium-3) fusion reaction, it appears to be completely clean. (Unless there are Helium-3 + proton, or Helium-4 + proton, or proton-proton reactions to worry about.) 96.233.31.53 (talk) 06:47, 29 September 2009 (UTC)

Efficiency of the fusion

Although in the article the MWhours are given the *.3 treatment from plant to electrical socket I read that the efficiency of Helium-3 fusion was one of the seductive reasons for its research, and that it was somewhere around 70% efficient due to the direct-to-electricity feature of the positive proton. Thoughts? Proof for my wild claim?

Kniesten 21:54, 29 June 2007 (UTC)

Does this sentence make sense to anyone?

This reaction produces a helium-4 ion (⁴₂He) and a high-energy proton (positively charged hydrogen ion) (¹₁p) and (alpha particle).

Huh?
(I'm not sure, but this sentence seems to be a victim of copy-and-paste disease.) —Preceding unsigned comment added by MegA (talk • contribs) 09:41, 14 September 2007 (UTC)

Well if anything it is guilty of stating the obvious... I couldnt have said it in fewer words myself... I mean if u wanna understand nuclear reactions in a sentence its gotta be that one...80.31.12.20 (talk) 21:35, 29 April 2008 (UTC)

No, the original reader is right-- the "alpha particle" has been mentioned already and it's not right to do it twice. Technically, alphas come only from decay of large nuclei, so this is really more of a helium ion (same thing-- different origin). For example, a high speed electron produced by a machine or from Compton scattering or internal conversion, is NOT a "beta particle". Saying "beta" implies more than a thing, but also a history (i.e., beta decay). Same with alpha (they only come from alpha decay). So I've removed the term, and explained it. SBHarris 00:23, 30 April 2008 (UTC)

The component on Manufacturing could be written better

"However, the production and storage of huge amounts of the gas tritium is probably

uneconomical, as roughly eighteen tons of tritium stock are required for each ton of helium-3 produced annually by decay (production rate dN/dt from number of moles or other unit mass of tritium N is N γ = N * [ln2/t½] where the value of t½/(ln2) is about 18 years; see radioactive decay). If commercial fusion reactors were to use helium-3 as a fuel, they would require tens

of tons of helium-3 each year to produce a fraction of the world's power.[19]"

This seems to imply that 18 years worth of tritium would be required annually. That is not the case. Once the stockpile is established, only the decay products need to be replaced. Therefore (slightly more than) a tonne of Tritium is required to replace a tonne of Helium-3. Since the needs for helium-3 will grow over time, there is a requirement to produce more Tritium each year than the annual consumption rate. This will result in a slowly increasing stockpile of Tritium that needs to be 18 times the annual consumption rate.

You're right-- it should be written so it can't be misunderstood. Will fix. SBHarris 22:47, 9 February 2009 (UTC)

"Breeding tritium with lithium-6 consumes the neutron, while breeding with lithium-7 produces

a low energy neutron as a replacement for the consumed fast neutron. Note that any breeding of tritium on Earth requires the use of a high neutron flux, which proponents of helium-3 nuclear

reactors hope to avoid.[citation needed]"

.

Tritium may be produced as a byproduct by impacting Nitrogen with high speed protons from the Deuterium Helium-3 reaction.

Got a citation? SBHarris

I have a lot of difficulty understanding the basis for this sentence:

However, the production and storage of huge amounts of the gaseous tritium is probably uneconomical, as tritium must be produced at the same rate as helium-3, and roughly eighteen times as much of tritium stock is required as the amount of helium-3 produced annually by decay (production rate dN/dt from number of moles or other unit mass of tritium N, is N γ = N ln 2/t½ where the value of t½/(ln 2) is about 18 years; see radioactive decay). If commercial fusion reactors were to use helium-3 as a fuel, they would require tens of tons of helium-3 each year to produce a fraction of the world's power, implying need for the same amount of new tritium production, as well as the need to keep 18 times this figure in total tritium breeder stocks.[30]

Current world 3He production is already in the tens of tons per year. The 2010 CRS report gives the price of 3He at only $100/liter! The complete conversion of the US electricity grid to 100% 3He fusion is not realistic. Production from lithium was recently started (2006) by the DOE; the same process (lithium irradiation) could be used at many other light-water reactors. Most significantly, the largest potential source of tritium, stripping from the coolant in CANDU reactors, is not even done at most CANDU reators today because of the "low" price of tritium. Why would storage of the tritium be difficult? The Whittington paper referred to in the article suggests that one must store the tritium for ten half-lives, 136 years, to extract "all" the helium-3, suggesting that one has the storage facility operating the entire period with gradually declining production. But in reality the helium-3 would be continually removed and tritium added, so the storage vessel would always be filled with tritium and production would always be at the maximum rate. This method is already in use.

At the tim — Preceding unsigned comment added by Danwoodard (talk • contribs) 22:37, 28 August 2011 (UTC)

Helium 3 on other planets?

I have been looking and looking, but cannot find a thing on Helium 3 on other planets. Like Mars? Would Mars have more h3 than Earth? Or even the Moon? Or less. - Curious, 212.251.151.81 (talk) 22:18, 9 February 2009 (UTC)

Just did a quick google search for "He3" "He3 gas giants" and "He3 lunar" and, just looking at the search results, there seems to be quite a bit of information on the subject.173.22.123.35 (talk) 21:41, 15 April 2009 (UTC)

Needs Reference

"Due to the lower atomic mass of Helium-3 (3.0160293 amu), it has significantly different properties from Helium-4 (4.0026 amu). Because of the weak induced dipole-dipole interaction between helium atoms, their physical properties are mainly determined by zero point energy (groundstate kinetic energy), and lower mass of Helium-3 causes it to have higher zero point energy, which means Helium-3 can overcome dipole-dipole interaction with less thermal energy than Helium-4." This sentence isn't clear and needs a reference. (${\frac {p^{2}}{2m}}_{He-3}>{\frac {p^{2}}{2m}}_{He-4}$) —Preceding unsigned comment added by 131.211.211.25 (talk) 18:58, 26 May 2009 (UTC)

Need expansion with this

Article in NYTimes: http://www.nytimes.com/2009/11/23/us/23helium.html? —Preceding unsigned comment added by 66.167.220.13 (talk) 02:11, 24 November 2009 (UTC)

Too much focus on extraterrestrial supplies

Helium-3 would also be a by-product of Deuterium-deuterium fusion (along with the more important tritium). I find that there is too much focus on lunar extraction from the space community and very little interest from the physics and engineering side. I think the article should reflect reality and downplay the extraterrestrial supplies to be in line with fusion research rather than the space exploration fringe – they are not plasma physicists. —Preceding unsigned comment added by MONDARIZ (talk • contribs) 17:01, 21 November 2010 (UTC)

Can you name an on-Earth means to get He-3 for Aneutronic fusion WITHOUT going through highly neutronic processes first? (Cat add Pipe dream please!) Hcobb (talk) 21:59, 21 November 2010 (UTC)

No. But maybe it should just be mentioned that Helium-3 is thought to be more abundant on the moon and then link to Exploration_of_the_Moon#Recent_exploration. I fail to see what space exploration has to do with this article, other than promoting the idea of lunar mining. —Preceding unsigned comment added by MONDARIZ (talk • contribs) 07:54, 27 November 2010 (UTC)

Helium-3 sells for about $100/liter even during a "sortage". : http://www.fas.org/sgp/crs/misc/R41419.pdf and there is considerable use in industry already. If more is needed it can be produced in large quantities by extracting tritium from the heavy water in CANDU power reactors, more of which can be built if the price of tritium rises. The fact that tritium must be stored while it decays is portrayed as an obstacle, but why? The tritium is simply stored as tritiated water and the helium 3, which is nonradioactive, forms in it as a dissolved gas. The "required amount" for fusion is given in the article as 100% of the electric power consumption of the US. This is not realistic. No evidence is provided that extraterrestrial supply is economical or necessary. — Preceding unsigned comment added by Danwoodard (talk • contribs) 20:14, 28 August 2011 (UTC)

Order of sections

The order of sections does not seem optimal. Properties should come first, then then usage and applications, then production, and finally abundance and possible extraterrestrial sources of supply. Danwoodard (talk) 22:40, 7 September 2011 (UTC) After some thought, I think it would be logical to order the sections as: 1. Properties 2. Current Production 3. Current Applications 4. Potential Application as a fuel for controlled fusion 5. Potential sources Danwoodard (talk) 15:21, 15 October 2011 (UTC)

Equations of state

This should just be presented as a diagram, P vs T and state. This could do with more pictures. Equations can be on the image information page. Graeme Bartlett (talk) 20:09, 8 November 2011 (UTC)

Helium-3 production: The source of world peace????

The current edit has (since September 2011) contained the following passage under the heading “Production”:

“Current supplies of helium-3 come, in part, from the dismantling of nuclear weapons where it accumulates,[27][28] however the need for warhead disassembly is diminishing. Consequently tritium itself is in short supply, and the US Department of Energy recently began producing it by the lithium irradiation method at the Tennessee Valley Authority's Watts Bar reactor.[25]”

This passage is profoundly confused and gravely misleading. It seems to say that:

‘Helium-3 accumulates in nuclear weapons. The dismantling of nuclear weapons is a source of Helium-3. There is a need for dismantling nuclear weapons, but the need for dismantling nuclear weapons is diminishing. Because of (some or all? of) the foregoing, tritium is in short supply too and the DoE has begun producing tritium by lithium irradiation at the TVA's Watts Bar reactor.’

There are many false ideas lurking in there. The most misleading may be that dismantling nuclear weapons is an important source of Helium-3 and that Helium-3 is somehow trapped in nuclear weapons and that you can get more Helium-3 by liquidating nuclear weapons. The implication being that the more nuclear weapons we dismantle, the more Helium-3 we can get.

Reality is effectively the opposite. Yes, Helium-3 accumulates in the Tritium reservoirs of nuclear weapons. Yes, when nuclear weapons are dismantled their Tritium reservoirs are emptied and the Helium-3 therein is recovered. The problem with the notion in the article is that every bit of Helium-3 recovered from Tritium reservoirs in this manner would otherwise have been recovered by the Tritium reservoir recycling that is a standard part of nuclear weapon maintenance.

Tritium produced for the weapons program decays at a predictable rate from the moment of its production. Whether that Tritium is held in central reservoirs for weapon maintenance or in the Tritium reservoirs of individual warheads, it all produces Helium-3 at this same rate and that Helium-3 will be periodically recovered. (As a neutron absorber, Helium-3 poisons the D/T reaction that is at the heart of the weapons applications of Tritium.)

With the end of Tritium production at the Savannah River Site in 1988, the DoE’s stock of Tritium began declining at a predictable rate, halving every 12.32 years. Almost all of the U.S. nuclear weapons rely on Tritium to function. Before the DoE’s Tritium stock could approach critical levels for weapon stockpile maintenance, the process of nuclear weapon stockpile reduction by dismantlement went into full swing, liberating (cannibalizing) Tritium for use in other weapons, reducing the total amount of Tritium needed for weapons stockpile maintenance, and deferring the need for Tritium production to be restarted. In 2003, the DoE began Tritium production at the Watts Bar reactor. [“Lithium irradiation” (neutron bombardment) was the method used to produce Tritium at both the Savannah River Site Watts Bar.]

So how does the dismantling of nuclear weapons relate to Helium-3 production? Dismantling of nuclear weapons produces no more Helium-3 than weapon maintenance does. Instead, the net reduction in the number of US nuclear weapons reduces the need to produce Tritium and thus reduces the amount of Helium-3 the US nuclear weapons program produces. Had nuclear weapons stockpiles been properly maintained at their former levels instead of being dismantled, larger amounts of Tritium would have been needed by the program and therefore larger amounts of Helium-3 would have been continuously produced.

The current edit is, in this respect, a convoluted mess and needs to be fixed.

I would suggest a passage like the following:

“A major source of Helium-3 is the maintenance of nuclear weapons. Tritium is a critical component of most nuclear weapons and it is produced and stockpiled for use in such weapons. However, over time, Tritium decays into Helium-3. Moreover, the buildup of Helium-3 in weapons blocks the effectiveness of the Tritium. Therefore, the Tritium reservoirs of these weapons must be regularly cleaned of Helium-3 to keep the weapons working. The Helium-3 collected during this process is retained for other uses and sale, as is the Helium-3 similarly cleaned from the Tritium stockpile itself. For decades this has been, and remains, the principal source of the world’s Helium-3.”

This has been a waste of my time.

Criticality (talk)

Neither references [27] or [28] say that He-3 from tritium decay is sold for other uses, and the "major source" sentence should be deleted if there is no source. :In fact [27] talks about recycling He-3 back into tritium by neutron capture, a process that is documented in Tritium along with other tritium production methods.

The point of using He-3 for fusion instead of tritium is to avoid neutron production, but all tritium production requires neutrons, so producing He-3 for fusion via tritium makes no sense - it is just moving the neutronicity and potential for neutron leakage further back in the process. This idea is apparently WP:OR and should be dropped from the article unless referenced. --JWB (talk) 18:49, 7 January 2012 (UTC)

(1) Your comments are patently disingenuous. I never made an edit to the article in this regard. I proposed some text as an example of a text that more accurately reflects the facts (i.e. reality, the world, all that good stuff). Footnotes 26 & 27 are in the extant article text and were put there by someone other than me. If I had edited that part of the article myself--which I obviously chose not to do--I would have opted to include better citations. For example . . . the source in footnote number 25! Which also has tons of information about Helium 3. It even has passages in it like these:

"For many years the supply of helium-3 from the nuclear weapons program outstripped the demand for helium-3. The demand was small enough that a substantial stockpile of helium-3 accumulated." "In addition to the nuclear weapons program, potential sources of helium-3 include tritium produced as a byproduct in commercial heavy-water nuclear reactors; extraction of naturally occurring helium-3 from natural gas or the atmosphere; and production of either tritium or helium-3 using particle accelerators. Until recently, the ready supply of helium-3 from the nuclear weapons program meant that these alternative sources were not considered economic. With the current shortage, this perception may change." "How Is Helium-3 Made? By far the most common source of helium-3 in the United States is the U.S. nuclear weapons program, of which it is a byproduct. The federal government produces tritium for use in nuclear warheads. Tritium decays into helium-3. This means that the tritium needs of the nuclear weapons program, not demand for helium-3 itself, determine the amount of helium-3 produced." "How Do Consumers of Helium-3 Obtain Supplies? Helium-3 does not trade in the marketplace as many materials do. It is produced as a byproduct of nuclear weapons maintenance and, in the United States, is then accumulated in a stockpile from which supplies are either transferred directly to other agencies or sold publicly at auction. The U.S. producer of helium-3 is the National Nuclear Security Administration of the Department of Energy (DOE). The seller for the public auctions is the DOE Office of Isotope Production and Research." "From the perspective of the weapons program, the extracted helium-3 is a byproduct of maintaining the purity of the tritium supply. This means that the tritium needs of the weapons program, not the demand for helium-3 itself, determine the amount of helium-3 produced." "At present, the nuclear weapons program, in effect, subsidizes the cost of production for helium-3, because the program must manufacture and purify tritium for the ongoing maintenance of its nuclear weapons." [ . . . and so on.]

I didn't edit the article, so I don't need to use the sources that are in the article now, much less the two you picked out.

(2) Yes, He-3 can be recycled into tritium via neutron bombardment. So what? It might matter if He-3 were so plentiful that it was actually worth using the available (scarce and expensive) neutron capacity on an He-3 target rather than on Lithium-6, but the relative scarcity of He-3 makes the exercise economically pointless.

(3) The rest of your comments are irrelevant to the material in this section.

Criticality (talk)

I was agreeing with you that the passage you discussed was incoherent, not saying that you authored it. It would best be dropped rather than trying to rewrite some sense into it. --JWB (talk) 20:42, 29 January 2012 (UTC)

Spin-structure studies

I suggest maybe considering the addition of something relating to the use of ³He in particle/nuclear physics research? It has important uses beyond fusion, which seems to take up the bulk of the article. In particular, polarized ³He can act effectively like a polarized neutron, allowing polarized np/en collisions in colliders, a crucial part of spin-structure studies. For example, HERMES, among others.

ChasEpstn (talk) 22:28, 20 January 2012 (UTC)

Critical Point

Only the critical temperature is given in "Physical properties", without a citation. A recent paper giving both critical temperature and pressure based on a literature survey is Cryogenics 46 (2006 ) 833–839. Maybe their empirical vapor-pressure fit would also be worth mentioning?

Layzeeboi (talk) 17:58, 27 February 2012 (UTC)