Talk:Joint European Torus

Untitled

What is the Microsoft JET engine? (apart form being "the thing that makes MS Access crash") -- Tarquin 08:20 5 Jul 2003 (UTC)

Moved?

This was moved from JET, the normal name for the thing, to Joint European Torus - why? The normal action would be to have a note at the top of the page...
James F. (talk) 22:34, 15 Nov 2004 (UTC)

Indeed. As a former employee on the project, I can tell you that it is always called 'JET', and the full-name never used. Dan100 19:04, Dec 14, 2004 (UTC)

Still it's full name is "Joint European Torus" and its how we refer to it in our own PR material. (I'm a current PhD student on JET) --CnlPepper 00:04, 13 Jan 2005 (UTC)

(puke) we have differnt disabiguation pages at JET and jet (disambiguation) my suggestion would be to redirect JET to here and add a pointer to jet (disambiguation). Plugwash 01:48, 8 Mar 2005 (UTC)

Agreed. Since no one seems to object, I've taken the liberty of merging JET into Jet, and redirecting to Joint European Torus - Jak (talk) 18:12, 25 June 2006 (UTC)

Most powerful reactor?

JT-60's wikipedia entry claims that it is "the world's most powerful fusion reactor." This contradicts the claim in this article that JET "is the largest and most powerful nuclear fusion reactor yet built." Unless they're both equal in power, they can't both be the most powerful... TerraFrost 04:34, 7 Mar 2005 (UTC)

It's so hard to define 'powerful'. Powerful in what way? Maximum heating capability? Alpha-particle self-heating? Total fusion power liberated? I think that unless one is being very specific, it's best to avoid using the term. Dan100 19:55, Mar 7, 2005 (UTC)

The last sentence of the first paragraph appeared confusing to me: "It was the largest machine in production when the JET design began." How could JET be the largest machine in production when the design began? :-) I made it clearer by changing to: "At the design stage JET was larger than any such machine then in production." This omits the previous entry's reference (as shown). Unfortunately the link associated with that now seems out of date. CatNip48 (talk) 19:11, 21 August 2021 (UTC)

Theory

i've just added a lot of theory, pretty much doubling the length of the article. however i am worried about copyright. i based my writings on a HowStuffWorks article, even "stealing" a photo. i hope that, as a educational website, they will have no quarrel with me. can anyone help with the copywrite? i'm out of my depth. mastodon 17:57, 18 January 2006 (UTC)

Fusion and nuclear waste

I was about to post a comment on the talk page of cold fusion, when I saw that what I think is a fairly basic piece of misinformation is repeated on this article.

The second paragraph of the cold fusion article currently reads Hot nuclear fusion using deuterium has the potential to yield large amounts of energy, uses an abundant fuel source, and produces only small amounts of manageable waste...

On the same theme, this article (Joint European Torus) currently lists under advantages: Less nuclear waste - Fusion reactors will not produce high-level nuclear wastes, as fission does, so disposal will be less of a problem. In addition, the wastes will not be of weapons-grade nuclear materials as is the case in fission reactors.

That seems wrong on two grounds. Firstly, the development of lining materials to withstand the enormous neutron flux of a sustained D-T reaction at all is a key unsolved problem. The development of such materials that will not become high-level waste is an even bigger challenge, which the proposed materials testing reactor to be constructed in Japan as part of the ITER project will seek to address. So this is really speculation, but it reads as fact.

Secondly, the wastes produced by most fission power stations are anything but weapons-grade, and every new technology that extends the fuel life (more to minimise refuelling stoppages than to reduce fuel usage but it's still a strong trend) makes the spent fuel even less useful for weapons.

It seems pointless trying to fix the cold fusion article while we have such misleading statements in this one.

See http://www.iop.org/EJ/abstract/0029-5515/43/7/301/ for one paper that hints at some of the challenges. Comments welcome. Andrewa 16:12, 10 February 2006 (UTC)

The majority of the high level waste produced from a fission plant is the by-products of the fission reaction - products such as cobolt-60 and strontium-90. Nasty, nasty stuff. Fusion does not have this source of waste, the by-product of D-T fusion is non-radioactive helium. The advantage of fusion in this regard is correctly stated, a fusion reactor would not produce anywhere near the volume of waste a fission reactor does. CnlPepper 10:12, 5 April 2006 (UTC)

Cobalt-60 is still produced in the JET reactor as a by-product of neutron activation from the D-T fusion. Although the levels are much lower than that present in fission reactions, it is still present and is still a very nasty by-product. — Preceding unsigned comment added by 194.81.223.66 (talk) 14:58, 9 April 2013 (UTC)

How is Cobalt-60 produced in JET? The elements exposed to neutron flux are all low atomic number such as Hydrogen, Helium, Beryllium and maybe Carbon. To produce Cobalt-60 from neutrons would require some common Cobalt-59 to be present. I think it is safe to assume that the designers will not include anything like CO-59 in the structure which is known to produce nasty isotopes under neutron irradiation. Mtpaley (talk) 22:12, 7 June 2013 (UTC)

World Record

Eeer, JT-60 achieved a larger power output, didn't they? They had 55 MW of RF and NBI heating, and a Q of 1.25... Danielfong 01:35, 1 March 2006 (UTC)

No, JT60U does not run with Tritium. The Q of 1.25 they claim is an estimate of the fusion power that would have been achieved if the D-D fusion plasma in which the experiment was performed were replaced with a D-T plasma. The JET record is a real D-T shot, ie JET really produced power while JT60U did not (D-D fusion produces negligible power in current devices). I've added a referece to the relevant JT60U paper and clarified this the text (btw I forgot to log in before my last edit, the edit listed as 194.81.223.66 is me). CnlPepper 10:12, 5 April 2006 (UTC)

How much electricity can it make?

I was just curious as to how much electricity a fusion reactor can make.

Can you throw out a generic guess like "its gonna be 20 times more powerful than a fission reactor, produce less than 1% of the waste, and after all research is done, cost only 5 times as much to produce additional ones," or something like that?

Or does it produce the same amount of heat that a fission reactor does, for far less in fuel cost? Or three times as much heat, allowing you to turn 3 times as much water into steam, that steam rising up to turn turbines and thus produce electricity. Dream Focus 05:33, 2 February 2007 (UTC)

The real answer is noone knows yet. If fusion works out then there should be basically no high level long lasting waste (there will still be a lot of the low level stuff because of the neutron bombardments on parts of the reactor) but its hard to come up with concrete figures when you don't even have a working (over breakeven) reactor and noone knows just how well the reactor materials will hold up under sustained neutron bombardment. Fuel costs should be relatively minor (lithium is a common metal and duterium can be obtained by using isotope sorting methods on ordinary hydrogen)

The really big advantages though are it would be virtually impossible to weaponise (fusion bombs do not use anything made by fusion reactors) and it would not be at risk of a meltdown since the reaction isn't self sustaining. Plugwash 21:31, 2 February 2007 (UTC)

Unbalanced content

Seems to have too much about staffing and construction, and needs more on the engineering design and science programs and results. - Rod57 (talk) 12:59, 7 October 2011 (UTC)

flywheels

One of the interesting design decisions in JET was to not use superconducting magnets (for reasons of cost). Instead, the magnets are made from thick copper, with internal water pipers for cooling. They are powered via the flywheel generators. The amount of energy stored in the flywheels (and the amount of temperature rise tolerable for the magnets) is the main reason why JET cannot operate for more than 30 seconds at a time. — Preceding unsigned comment added by 82.10.237.122 (talk) 23:59, 1 May 2014 (UTC)

We should mention that (with a source) - maybe in a new section on critical design decisions. I estimate it takes about 20 mins to spin up the flywheels (at 8.8 MW each), and presumably less than an hour to re-cool the coils since they can average 22 shots/day. - Rod57 (talk) 19:50, 5 December 2015 (UTC)

The flywheels are maintained at half speed (112 rpm) and are accelerated to operational speed prior to pulse countdown. Acceleration is 13 rpm per minute to a speed calculated to be sufficient to deliver power for the scheduled pulse. Jkgoff (talk) 18:45, 8 September 2022 (UTC)

The mass units need to be consistent, or at least clarified. Is the mass unit a metric tonne or an Imperial ton? — Preceding unsigned comment added by Togo59 (talk • contribs) 18:18, 7 July 2024 (UTC)

Only one to have used D-T fuel ? - No

Can we say, eg in lead, that so far it is the only magnetic confinement fusion device to have used tritium fuel, and [therefore?] is the only one to have generated fusion power (as shown by a neutron flux) ? - Rod57 (talk) 19:42, 5 December 2015 (UTC)

No. TFTR was also designed specifically to use D-T fuel with the express goal of reaching breakeven in order to garner political support. It ran on D-T shortly after JET's first attempts. That makes JET one of two machines to do this, with ITER being the next to try. Of course, NIF has also used D-T. Maury Markowitz (talk) 16:18, 15 December 2017 (UTC)

Power requirements

The reference says that peak power requirements can be over 1000MW. That's definitely not the same as "up to 1GW", as one is specifically under that figure and the other is specifically over it. The upper bound is greater than 1GW. Some runs may not demand so much power, and not surpass 1GW. I don't see a problem with the phrasing "up to over 1GW" as a way of expressing this, but in any case the current wording is flat out wrong.

201.230.243.47 (talk) 16:52, 9 December 2015 (UTC)

Looking great now!

201.230.243.47 (talk) 20:26, 9 December 2015 (UTC)

Goal of breakeven

In the introduction, it states that JET was "built with the ultimate goal of reaching scientific breakeven ". I don't think that this is true. This isn't supported by reference [1] (only relevant passage I could find is on page 25) and is contradicted in other contemporary references and . (see pages 25 and 17 respectively).

I have modified the passage to "built with the hope of reaching breakeven [1,2,3]".

balljust (talk) 11:03, 25 January 2019 (UTC)

References

Here are some direct quotes from the JET Project Design Proposal (1976):

Source: https://op.europa.eu/en/publication-detail/-/publication/cc7f776b-5261-4f34-b4de-3734ddf0624c/language-en

"This proposal describes a large tokamak experiment, which aims to study plasma behaviour in conditions and dimensions approaching those required in a fusion reactor." (p. iv)

"The experiment known as the Joint European Torus (JET) involves building and studying a large tokamak type device and should yield decisive results on the practical feasibility and definition of a Tokamak reactor." (p. 1)

"Possible performance data for JET: Ignition Domain" (p. 18)

"The essential objective of JET is to obtain and study a plasma in conditions and dimensions approaching those needed in a thermonuclear reactor." (p. 25)

"The alpha particles may be produced by direct reactions from an energetic beam of deuterium injected into a tritium plasma, and in this case it is likely that the break-even condition will be reached. The break-even condition is obtained when the energy injected by the beam is equal to the energy released by the induced fusion reactions. In the event that the confinement of energy is long enough, thermonuclear reactions between the particles of the plasma itself may produce enough alpha particles to play a significant role in the energy balance." (p. 28-29)

Here are some direct quotes about TFTR in Popular Science (1978):

"TFTR will achieve not just a power break-even, but will be a net producer, in terms of heat." Anne Davies, U.S. Department of Energy, quoted in Popular Science, 1978

"TFTR is the next generation. It is where we try to get out as much energy as we put in." Anne Davies, U.S. Department of Energy, quoted in Popular Science, 1978

"The TFTR will not be an ordinary fusion research device. For some 30 years, physicists have been trying to achieve breakeven fusion energy — to get out more energy than they put in. The TFTR seems likely to reach that goal in the early 1980s. When that happens, scientists will have proved that fusion power is scientifically feasible. The next step will be to construct a fusion reactor that generates electricity." - Edward Edelson, Popular Science, 1978

StevenBKrivit (talk) 16:10, 18 July 2020 (UTC)

Hi - Per WP:LEAD, the lead section of the article should be a summary of the main text. It should not introduce any new material. I did a lot of work to clean this article up in 2016 but a lot of new material seems to have crept in. I will take another look. Best wishes. Dormskirk (talk) 16:42, 18 July 2020 (UTC)

Hi Dormskirk: You have removed the three sentences that discussed the primary goal of JET: reaching scientific breakeven, a goal which JET failed to achieve.

"This is also the world record for Q, at 0.67. A Q of 1 is scientific breakeven, a point JET was not ultimately able to reach."

"JET was specifically designed to approximate the conditions required in a commercial fusion reactor. Its designers also hoped that it might achieve ignition."

"Both were built with the hope of reaching scientific breakeven"

This will please fusion advocates and it will benefit the public relations for the fusion community, but it reduces the accuracy and value of this Wikipedia article for the general public. Perhaps it was not your intention to systematically remove this information? I don't fight with other editors on Wikipedia, therefore, I will leave it to you fix, if you want to do so.

StevenBKrivit (talk) 17:57, 18 July 2020 (UTC)

I have added in the "Q at 0.67" But left out the other matters. It is entirely a matter of following the wikipedia guidelines. The lead should be a summary of main article and at the moment the other matters are neither mentioned in the main text or sourced. Best wishes. Dormskirk (talk) 18:12, 18 July 2020 (UTC)

In fact, breakeven is mentioned in the main text: "Although very successful, JET and its counterpart TFTR failed to reach breakeven."

If you need a source, I would propose the actual design spec, page 28: "The alpha particles may be produced by direct reactions from an energetic beam of deuterium injected into a tritium plasma, and in this case it is likely that the break-even condition will be reached."

Perhaps you would like to add this authoritative source to help improve the article?

StevenBKrivit (talk) 18:23, 18 July 2020 (UTC)

I think it would be helpful to add a bit more in the main text (but not in the lead for the moment). Breakeven needs to be explained in simple terms. I am just a bit concerned that the text from page 28 is too technical. It assumes the reader knows about alpha particles. Best wishes. Dormskirk (talk) 18:31, 18 July 2020 (UTC)

I actually think there is already enough in the main text on breakeven. Surely the words "JET set the record for the closest approach to scientific breakeven" already implies that breakeven was not achieved. Dormskirk (talk) 18:37, 18 July 2020 (UTC)

I'm not suggesting adding more text. I'm responding to one of your original concerns that the goal of JET breakeven was not sourced. I've provided a source. Why would you not want to improve the article by citing this source?

StevenBKrivit (talk) 18:43, 18 July 2020 (UTC)

OK. I get it now. I will add something. Best wishes. Dormskirk (talk) 18:47, 18 July 2020 (UTC)

Nice. Thanks for your contribution. Because there has been such pervasive public misunderstanding about scientific breakeven versus engineering breakeven, and respectively, Q_fus versus Q_eng, I'll add "scientific" in two more places. I will leave it to others to decide whether to disambiguate between the two Q values.

StevenBKrivit (talk) 19:13, 18 July 2020 (UTC)

Add notable experiments and results ?

The only mention of specific experiments and notable results seems to be in the intro. Can we have a larger section with a little more detail ? Maybe chronological ? If there had been lots of detail I was hoping to add something like :

He-3 used as radio energy absorber in multi-ion plasma

Both MIT's Alcator C-Mod tokamak and the Joint European Torus (JET) have experimented with adding a little He-3 to a H-D plasma to increase the absorption of radio-frequency (RF) energy to heat the H & D ions, a "three-ion" effect. --- Rod57 (talk) 08:39, 18 July 2020 (UTC)

References

Incorrect Information Provided Regarding JET Efficiency

Regarding the mod on 20 March by anonymous editor with IP 100.6.43.48 as follows:

• The driver was 100 MW. The Joint European Torus used large flywheels to provide the pulsed power to run the machine. Those flywheels created ~100 megawatts of power to run JET for the short (tens of seconds) of time needed to create the 16.1 megawatts. By that measure, the efficiency of this machine was 16%.

This is contradicted by the fact, as first published by me, in 2016, that the JET reactor consumed power at a rate of 700 MW. My source was Nick Holloway, the spokesman for CCFE/UKAEA who provided that information to me on 1 December 2014, as follows:

In 2015, Holloway added a page on the EUROfusion Web site that says: "In total, when JET runs, it consumes 700 – 800 MW of electrical power (the equivalent of 1-2% of the UK’s total electricity usage!)."

Thus, the efficiency of the machine was 1% when input/output values are normalized to electric. StevenBKrivit (talk) 01:56, 21 March 2021 (UTC)

References

Thanks for that. I have removed the edit by IP 100.6.43.48 as it was unsourced. Dormskirk (talk) 10:17, 21 March 2021 (UTC)

I just received this message from DR Matt Moynihan, on my Talk Page:

"The Joint European Torus was not set up for power capture. Hence, 16 MW of power out of 23 MW of power in the plasma is a Q of 0.67. But with 100 MW in the fly wheels, the efficiency was closer to 16%. IF they had had electrical capture they efficiency would have closer to 4%. I have these numbers from Mark Henderson, Electron Cyclotron Section Leader at ITER.I am publishing a book on Fusion with Nature-Springer. Once my book is published, I will come back and cite my book with that information. Thanks, Dr. Matt Moynihan www.fusionconsultant.net — Preceding unsigned comment added by 100.6.43.48 (talk) 17:33, 25 March 2021 (UTC)"

I believe that no response to him is necessary at this time.

StevenBKrivit (talk) 21:07, 25 March 2021 (UTC)

Image size

Again, as so often in Wikipedia, here a "trap" of an clickable image (the top right image, link https://en.m.wikipedia.org/wiki/File:JointEuropeanTorus_external.jpg), that does NOT appear in an expected bigger size then (would expect full-screen best), but in that near stamp-size format again. Disappointing for users, lost time, annoying and distracting at least me from using Wiki for the next time. Maybe an iPadOS problem (latest version)? 2001:16B8:261D:9800:CD61:C01E:86FA:FDDF (talk) 14:38, 1 July 2022 (UTC)