Talk:Liquid fluoride thorium reactor

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This otherwise excellent section refers to "Pu239, a toxic transuranic element". For a start, it should say "toxic transuranic isotope" But by what criterion is Pu239 more toxic than U233? If this refers to its chemical toxicity, how is that different from all the other actinoids, thorium and uranium in particular? Presumably we are referring to the radiotoxicity and long life of the particular isotope. But Pu239 is long lived precisely because its rate of radioactive emission per atomic nucleus, is slow! Admittedly, U233 is only one third as radioactive as Pu239, but that's because it's longer lived. The advantage of the continuous breeder reactor is that neither the radioactivity nor the long life matters, because the reactor consumes the product. Plutonium-239 breeding is perhaps inferior to the LFTR scheme, but let's not feed the idiotically false popular belief that plutonium is more toxic than anything else.

The article states that protactinium separation is part of the LFTR design. This allows the newly created Pa-233 to escape further neutron capture and decay undisturbed to U-233; this permits a breeding ration > 1. A weapons proliferation concern is that such separated U-233 may be used for a weapon. Most LFTR advocates I know (Hargraves, Moir, LeBlanc,...) prefer a design with no Pa separation and a breeding ration ~1.0, not presenting the risk of U-233 separation and ensuring that any U-233 is contaminated with U-232 whose decay chain emits 2 MeV gamma rays too hazardous for weapons workers. So, could somebody revise the article to illustrate this? — Preceding unsigned comment added by Robert Hargraves (talkcontribs) 22:36, 14 December 2011 (UTC)

I'll try to change the impression by discussing the trade-offs. I wrote some of the original text and I may be responsible. Ray Van De Walker 07:24, 8 January 2012 (UTC)
Some oder designs used separation of Pa to work with a low fissile inventory. An alternative to Pa separation is using a larger fissile inventory - something like 2 to 3 times the inventory has the same effect as reprocessing every 10 days. Many newer designs go that way, since this reduces proliferation concerns, and one can do reprocessing at a much lower rate, thus saving a lot on the reprocessing capacity.--Ulrich67 (talk) 16:07, 30 April 2012 (UTC)

Sources for LFTR?[edit]

Which sources actually use the term "liquid fluoride thorium reactor"? --JWB (talk) 18:37, 22 August 2008 (UTC)

I am new to this and may have put things out of place. The first two items under 'External Links' are good sources for the actual word LFTR. The first two links in 'References' are the technical background but may not use the term. Also I noticed the last external link may not be appropriate or maybe that is Wikipedia's redirection to sponsor books in the nuclear field. (JAJAB (talk) 14:37, 29 August 2008 (UTC))

If it's simply a synonym, this should be a redirect to the MSR article rather than a separate article. The Energy From Thorium link refers to the original Oak Ridge project as liquid-fluoride reactor, so there's no evidence this term is a new one applying to new work and differentiating it from the older work. --JWB (talk) 18:20, 29 August 2008 (UTC)

That is where this all started from. I have gotten many complaints that LFTR was a link to MSR and then it was never mentioned in the article at all - which did not make sense. Also the MSR article is far to large and complicated. It is trying to span too broad an area as it is. The different salt combinations have separate pages to cover their properties. By the same token, Navy ships are given a page as well as the ship class. As far as the technical work, I was told just today by another researcher the important difference LFTR will make over the MSR. I also asked a few of the other nuclear developers to add to this article. Are you in the nuclear field or have technical background in this area? (JAJAB (talk) 04:36, 30 August 2008 (UTC))

Whether this is a separate article or not, if this is a distinct molten salt reactor design, it should have a subsection in the MSR article, with link to the separate article with more detail if one exists. If the description is short, it can fit in the MSR article.

The MSR article is 34k, which is slightly below the WP:Article size suggested limit. If we start breaking it up, the policy mandated method is WP:Summary style which has a main article with summaries, linking to detail articles with more detail.

So far the only one of the four references and three links in this article that uses the term "Liquid Fluoride Thorium Reactor" as a primary description is the Naval Postgraduate School link, which is about a single student project. Kirk Sorensen's site mentions the term but seems to use it interchangeably with MSR.

If you can add substantial information from references that use LFTR as a separate term and explain why MSR is not applicable, then this should be a separate article with that information. Right now almost all the material is about MSRs, using the term MSR, and also using liquid fluorides and thorium fuel, but not using the term LFTR much less defining it as separate. --JWB (talk) 22:44, 30 August 2008 (UTC)

JWP, this is the issue: more and more LFTR is becoming THE term to use for the...Liquid Fluoride version of the MSR. I know we went though this before when the previous LFTR article was merged with the MSR article. But now, if you do a google search for LFTR, you will find dozens and dozens of references. You are going to have to get used to this term as THE specific sub-genre of the MSR. I didn't even start this entry, someone else did, so you can see that people WANT to know specifically about the LFTR and want to be able to look for it under it's own title. DavidMIA (talk) 15:05, 2 September 2008 (UTC)
I am presently asking for help in this regard from the nuclear technical community. It is a newer subject so technical articles are being prepared by several people, but good research is not published quickly and then it takes off in a flurry of papers. I believe we are at the "take-off stage". Nevertheless, it is discussed widely among various groups from environmentalist, to space power developers, to nuclear researchers. I think the shear size of the site is evidence of the interest and MSR may have the largest percent of documents, but I think LFTR is the primary topic (I wonder if Kirk Sorensen can tell what kind of net traffic he gets on that site?). I also disagree that LFTR is interchangeable with MSR. There are clear distinctions and maybe that should be a chart on the LFTR page. I have not read the full format manual but only look at what makes sense to someone coming to this site and looking at this subject (i.e., what do they expect to see). I am sure we can work this to everyone's satisfaction shortly and I am certain in less than a year this will not be an issue at all. —Preceding unsigned comment added by JAJAB (talkcontribs) 16:27, 2 September 2008 (UTC)
If it's a "term to use for the...Liquid Fluoride version of the MSR" that argues for the two terms pointing to the same article, regardless of which one (or both) are redirects and which is the primary article name.
By definition molten salts are liquid, and Molten salt reactor currently has 20 mentions of "fluoride" but only 3 of "chloride", confined to one short paragraph (1% of the article volume) briefly mentioning basic theoretical considerations (fast reactor, Cl-35 activation) but no actual development work. This 1% is not sufficient justification for a separate article.
Again, it's up to you guys to add references to substantiate whatever claims you make, whether that it's a new term for the MSR, that it's become more popular than MSR, or that it's a term with different significance. Googling myself, I'm finding references using the two as synonymous. The top two relevant hits for LFTR are from Energy from Thorium and use them as synonymous. --JWB (talk) 16:32, 2 September 2008 (UTC)
So far you haven't even proposed any way in which LFTRs are different, much less substantiated it. --JWB (talk) 17:02, 2 September 2008 (UTC)
The main difference is that the MRSs are they are currently being developed (France, Gen IV-US, etc) are all *Uranium* fueled using U238 as the fertile material. So it involves a different architecture and process. Factually speaking, all LFTRs are MSRs but not all MSRs are LFTRs. The only way to get around this is by USING this term, LFTR and as a separate, albeit somewhat redundant, entry. (talk) 01:47, 4 September 2008 (UTC) David
OK, so you agree "LFTR" *is* the traditional MSR. The MSR article is almost entirely about this line of development starting with Weinberg, and covers it in quite a bit of volume. Only the sections "Molten-salt cooled reactors" and "Liquid salt very high temperature reactor" are about other concepts.
Introducing the term "LFTR" is fine if you find references for it, but this is no case for duplicating most of the article content. It's hard enough maintaining the content in one place; let's try to get that accurate and well-written, which has been a problem so far, rather than creating a WP:POV fork against Wikipedia policy. Also, there's already the thorium fuel cycle article discussing many of the thorium reactor issues; this also needs work.
Uranium fuel does not make the plumbing any different - remember the Oak Ridge MSRE ran on various fuels. The only difference in physical plant that comes to mind is that you can omit the protactinium sequestration. Only the solid-fuel reactor with molten salt cooling is really a different design, which much more closely resembles liquid metal cooled reactors. --JWB (talk) 03:28, 4 September 2008 (UTC)

We should make MSR article only about general MSR concept, since thats what its called (it warrants a big reduction in content imho) and move more specific reactor subtype stuff into LFTR article. The whole section "Molten salt fueled reactors" was almost ONLY about LFTR and thorium fuel. There should be only brief description of LFTR subtype in the MSR article, with link to LFTR article for details.

Molten salt reactor Duplication[edit]

How does this topic differ from Molten salt reactor? It was a redirect to that article until recently. I don't see anything specific to liquid fluoride here.   Will Beback  talk  23:24, 19 October 2011 (UTC)

LFTR is a specific variant of MSR, combining the best features of the thorium fuel cycle and liquid fuel reactors (continuous reprocessing). It uses U-233 as the fissile material with thorium as the fertile material, both dissolved in fluoride salts. It is currently being investigated by several organizations (a change since the merge in 2008). AFAIK, only this variant is being actively pursued, hence the desire for a separate article. The aim is to move much of the LFTR-specific material out of the MSR article over time. --IanOsgood (talk) 00:33, 20 October 2011 (UTC)
It seems redundant, but if you have a plan for it I'm sure it will be OK.   Will Beback  talk  02:15, 20 October 2011 (UTC)

Folks, JWB has fought the separate LFTR entry for years as the record above shows. LFTR has come onto it's own and there are now at least 3 start ups in the US, not to mention the Chinese that are developing LFTR. The "MEME" is LFTR, not MSR. As noted, LFTR is a variant of the MSR and since it's receiving literally ALL the publicity about it, it needs it's own entry. The MSR article should be cut down to size with most of the data coming here filling out the LFTR one. The meme "LFTR" is now THE MSR in development. Wiki needs to acknowledge this and that's what's happened.--David Walters — Preceding unsigned comment added by (talk) 14:51, 25 October 2011 (UTC)

The article is developing nicely. Good work, editors.   Will Beback  talk  10:45, 8 November 2011 (UTC)
Perhaps some of the bullets under Design Challenges need to be condensed. HF is mentioned in two seperate bullets. Paladindythe (talk) 01:38, 13 November 2011 (UTC)

We now have duplication between several articles - Thorium fuel cycle, Molten salt reactor, Molten-Salt Reactor Experiment, Liquid fluoride thorium reactor, and others.

Stuff that is generic to the thorium fuel cycle should be primarily covered in that article. Stuff that is generic to breeder reactors should be covered in that cycle. Stuff that is generic to molten salts in reactors should be covered in that article. LFTR would be fine as an article on the specific proposals going by that name, if there are now published references for them, but should not be the primary article for the more general stuff - it should have summary coverage and "Main article:" links to in-depth coverage.

A big problem with "new nuclear" concepts is each group of promoters talks about its design as if it is completely new and independent of others. Wikipedia can provide value by having information on all and by comparing them. --JWB (talk) 20:37, 17 December 2011 (UTC)

The duplication still exists. JWB's suggestions seem good. We should start to replace duplications by references to the most appropriate 'main' article. - Rod57 (talk) 16:03, 23 March 2013 (UTC)

Design Challenges[edit]

I propose striking out the paragraph dealing with hydrogen inside the reactor. It has been pointed out that there are no hydrogen within the reactor. MegaHasher (talk) 06:59, 17 December 2011 (UTC)


All of the known disadvantages need to be listed (not just two) including that there are probably a large amount of disadvantages that are not even known yet, due to this technology not being mature. A lot of new research has to be completed before these things become mature enough to dot the earth with. There is a lot of potential, but still a lot of unknowns. This article is currently very biased and needs to be revised by a specialist in the needed field. This is Wikipedia people, not a cheer leading squad. Those with the knowledge, PLEASE make the needed additions/revisions. Thank you. — Preceding unsigned comment added by (talk) 21:51, 19 December 2011 (UTC)

I agree on both parts. Let me quote from the latest MIT study on nuclear power which had a section on AHTR/MSRs.
"As a new reactor concept, there have been limited studies—thus the difficulty to credibly assess this concept."


The page needs to make this explicitly clear and I have added it into the disadvantage section as well as another mentioned in the study. One could easily get the idea from the monumental list of advantages and the sheer size of the page that this isn't the case.
Also little things like this line:
"Unfortunately for MSR research, Weinberg was fired and the MSR program closed down in the early 1970s,[7] after which research stagnated in the United States"
Should read something like:
"The MSR programme was closed down in [exact date] due to reason [x]. No further research has been conducted.
Short and to the point, crucially with no subjective language (i.e Unfortunately). The page needs a lot of work. I would as someone above did question the need for such an extensive page on a single design as opposed to one umbrella page for MSRs. — Preceding unsigned comment added by (talk) 12:03, 3 January 2012 (UTC)
Yes, the occasional subjective language needs to be corrected into more neutral tone.ShotmanMaslo (talk) 19:40, 3 January 2012 (UTC)
I am no aware of any non-listed disadvantages of the LFTR existing. If you have a source for something new, feel free to add it. Yes, the advantages vs. disadvantages may seem biased, but thats simply the nature of the technology in question as far as I know. I was unable to find any more LFTR disadvantages or showstoppers in reliable sources. ShotmanMaslo (talk) 19:40, 3 January 2012 (UTC)

"The increased difficultly in prepossessing spent fuel from such makes a closed fuel cycle much difficult and therefore more expensive to achieve than in other designs. While this is good from a nonproliferation standpoint a closed fuel cycle does have benefits for civilian use and may be desired by some nations."

I have not found this in the citation, and it probably refers to traditional uranium solid fuel reprocessing closed fuel cycle, or solid fueled thorium reactor (AHTR) not online continual reprocessing of thorium fuel cycle as in liquid fueled LFTR. It is also a difficult to parse sentence. Should I remove it? ShotmanMaslo (talk) 19:17, 3 January 2012 (UTC)

I was unsure about adding it, here's the quote remove it if you think it's inaccurate.
"For a closed fuel cycle there would be significant challenges relative to LWR or SFR SNF in terms of recycling the SNF. The high-temperature reactor fuel that is the basis for this concept is difficult to reprocess and thorium fuel cycles generate 232U that has a decay product with a 2.6 MeV gamma ray that makes fuel fabrication difficult. The fuel has several other characteristics that create significant technical barriers against diversion relative to other types of SNF" — Preceding unsigned comment added by (talk) 23:51, 3 January 2012 (UTC)
indeed it refers to solid fueled thorium reactors (fuel fabrication, offline reprocessing), not LFTR. — Preceding unsigned comment added by ShotmanMaslo (talkcontribs) 06:36, 4 January 2012 (UTC)

External Links[edit]

There's far to many, they're all bias in favor of the technology and there's far to many blogs and news sources. I want to delete all of them except:

Thorium Energy Alliance (without the extra bit)
International Thorium Energy Organisation
Weinberg Foundation website
Flibe Energy company website

As "advocacy groups" or something.

The the most objective and informative videos (ie not ones trying to sell the technology) should stay. I haven't watched any though so I don't which fall into that category.

Media articles can go there's absolutely no need for them as can blogs -Wikipedia isn't a place to promote your personal blog.

Objections? — Preceding unsigned comment added by (talk) 13:02, 3 January 2012 (UTC) should also stay, it is the largest and oldest website about LFTR technology on the internet, with discussion forum and MSRE research document repository. Not a pure blog at all. Comparable sites on other energy articles are in the external links (for example Polywell forum on Polywell confinement fusion). — Preceding unsigned comment added by ShotmanMaslo (talkcontribs) 20:02, 3 January 2012 (UTC)

Which references use the term?[edit]

Not that many of the references listed use the term "liquid-fluoride thorium reactor". Could you point out which sources do use it, and especially sources other than Kirk Sorensen's publications, blogs, and news coverage. --JWB (talk) 20:29, 3 January 2012 (UTC)

Using an academic search engine for "Liquid Fluoride Thorium Reactor" there are 170 Results, 166 of which are 'other web', with only 1 journal source not actually on the topic (and a New Scientist article that Elsiver inaccurately promotes under 'journal sources' since they own the magazine)
Same search engine for "Thorium Molten Salt Reactor" gives 103 results of which 32 are journal articles. "Molten Salt Thorium Reactor" gives 4 total results, no journals.
Wouldn't this article be best as "Thorium Molten Salt Reactors" in general considering no such article exists as yet. Most if not all of the information about LFTRs would apply to TMSRs in general and it would allow for the article to spend less time promoting Kirk Sorensen and his business and more time providing information about TMSRs from journal sources rather than LFTR advocacy groups and new articles. — Preceding unsigned comment added by (talk) 02:20, 4 January 2012 (UTC)
I respectfully disagree with the theory that an article should be named according to the key words of academic articles. Instead, it should be titled according to common usage. LFTR is the more common usage on the net at this point. In large part that is because Kirk Sorenson began promoting it after forty years of obscurity. Ray Van De Walker 07:08, 8 January 2012 (UTC)
The WP:COMMONNAME policy calls for common English names used in WP:Reliable sources, not on the net. --JWB (talk) 18:57, 8 January 2012 (UTC)
I suspect that most WP:RS these days will end up quoting Sorensen; if so it's going to be LFTR. Examples: Wired Guardian another -- Limulus (talk) 10:15, 9 January 2012 (UTC)
Good secondary sources. Those would be good to add to the article on the recent origin and popularity of the term. --JWB (talk) 20:49, 9 January 2012 (UTC)

Production of Cesium 137 ocurs in all reactor types, because it is a common fission product. I think it has no relation to the LFTR's reduced production of transuranics. I intend to rephrase that part of the safety advantages. Ray Van De Walker 07:24, 8 January 2012 (UTC)

Synthesis of heavy elements[edit]

  • Th-232, U-235 and U-238 are primordial nuclides, having existed in their current form for over 4.5 billion years, predating the formation of the Earth; they were forged in the cores of dying stars through the r-process and scattered across the galaxy by supernovas.[4] Their radioactive decay produces about half of the earth's internal heat.[5]

This material really has nothing to do with the topic of the article, which is about a type of nuclear reactor. It could be added to every other reactor article, and the first sentence could conceivably be added to every article touching on every heavy element. Gold jewelry, mercury amalgam fillings, lead acid batteries, platinum catalysts, etc, etc. The cited sources makes no mention of the topic, liquid fluoride thorium reactors. This kind of general background belongs ion the thorium article, if anywhere.   Will Beback  talk  23:15, 26 January 2012 (UTC)

Actually no, I don't think it belongs in the thorium article because it also talks about U and Pu. It doesn't belong in articles about "every heavy element" because it's talking about fissile isotopes. It doesn't belong in every nuclear reactor article because most reactors only involve U; this describes the options that were presented in the 40's; Nuclear power and/or Nuclear fission would be appropriate, but I don't see what the harm in keeping a couple sentences regarding the origin of thorium is and how through identification and the process of and elimination we get to LFTRs. -- Limulus (talk) 20:22, 30 January 2012 (UTC)

Stable version template[edit]

As you can see above, I added the stable version template. I did this because this article was just found to meet class B criteria, and should the quality ever fall for some reason (as unfortunately happens with even Featured Articles that get demoted), this will hopefully preserve the hard work that has gone into this article thus far with an easy-to-access link. If you care to, you may read more about this new template in the template documentation, linked above. If for some reason you object to this template, feel free to discuss and remove it from this talk page. I just wanted to briefly explain what this is about! Thanks, Falconusp t c 19:48, 29 January 2012 (UTC)

Merging Disadvantages and Design challenges sections[edit]

I propose merging the separate Disadvantages and Design challenges sections into one section called "Disadvantages and design challenges", since the difference between them is very ambiquitous. Most disadvantages seems to have an engineering (design) solution to counter or mitigate them (and such design challenges can also be seen as disadvantages). Keeping it separate only causes editors to make duplicate entries. — Preceding unsigned comment added by ShotmanMaslo (talkcontribs) 20:27, 28 April 2012 (UTC)

Article is now over 91k in length. Please summarize into bullet points. Also remember all contents for Wikipedia must be verifiable, and no original research. That also applies to objections. Speculative, uncited objections cannot be included. Same applies to uncited explanation. MegaHasher (talk) 04:35, 3 May 2012 (UTC)
Some of the "Design Challenges" could also be seen as "Development Issues". Let's see what kind of headings work best. "Disadvantages" do not work that well because a later edit could make an item not a disadvantage. MegaHasher (talk) 23:37, 3 May 2012 (UTC)

I noticed that a lot of the 'disadvantages' points had counterpoints toward the end to soften them. But the 'advantages' tended to not have such counterpoints. The whole article seemed to me to be heavy on optimism, especially for a technology that hasn't been implemented in decades. (talk) 02:48, 23 June 2013 (UTC)

On Licensing[edit]

This could be unverifiable speculation. Merely been plausible is not good enough for Wikipedia. One google hit reads: "The Department of Energy is doing some research and development in the area of molten-salt cooled reactors (e.g., the Small Modular Advanced High Temperature Reactor), but the projects are not yet to the point where the NRC is involved in the review of the designs. If a technology appears destined for commercial applications in the foreseeable future, the NRC will engage designers in pre-application discussions and develop the needed regulations and guidance to support the review process (much as we are currently doing for small and medium-sized reactors using light water and gas-cooled reactor technologies). -Bob Jasinski" No evidence of NRC not going to license MSR. MegaHasher (talk) 05:59, 3 May 2012 (UTC)

Reprocessing Cost Unknown[edit]

"The costs and performance of the necessary reprocessing are uncertain." In other words, "I don't know." However, Encyclopedic content must be verifiable. Don't state what you don't know, but do state what you know (a verifiable result). One other issue is that this item is not a design challenge. MegaHasher (talk) 07:18, 3 May 2012 (UTC)

The reprocessing costs are unknown, but we know that we don't know. We even know that we can not know. To really know the costs one would need to have a running plant, or at least detailed plans.--Ulrich67 (talk) 12:49, 19 May 2012 (UTC)
Also, lack of reliable knowledge about what future cost to expect, is most definitely a "design challenge" for any sort of commercial venture, and may well be the most forbidding such challenge on the list. (talk) 00:33, 6 November 2013 (UTC)


Reverted the radiation objection. LFTR is a nuclear reactor after all. MegaHasher (talk) 05:08, 5 May 2012 (UTC)

Corrosion from large water ingress[edit]

Liquid fluoride salts have been injected into water with no violent reactions. Also there is no water inside the reactor. Appears to be null result. MegaHasher (talk) 04:02, 13 May 2012 (UTC)

Answer. Not really a null result... it's an important design criterium. With water cooled reactors, obviously having moisture ingress won't lead to any corrosion or safety issues. With a molten salt reactor this will cause chemical reactions. Not a safety issue unless very large water ingress comes into the reactor, though this seems like a deus ex machina considering the inherent safety, passive cooling, etc. Maybe call it a safety null result. Siphon06 (talk) 14:00, 12 June 2012 (UTC)

Increased Cesium-135 production[edit]

This increased Cesium-135 production also appears to be a null result. MegaHasher (talk) 00:02, 14 May 2012 (UTC)

Its not a real null result, it's just something like 5-10% more long lived fission products. So this is not good, but not a really bad thing either. It may be ok to leave it out.--Ulrich67 (talk) 12:53, 19 May 2012 (UTC)

Answer: It's not a null result, it's an advantage for the LFTR. There are other long lived fission products other than Cs-135. The production of these is reduced simply by the increased thermal to electrical efficiency. As was shown in one of the references the Cs-135 contribution to long lived total fission products is relatively small. Since one of you guys deleted the entire section, this fact was also lost... which is why I ask, please don't delete entire sections that have several references in them.

Delayed Neutron[edit]

Yet another null result. MegaHasher (talk) 00:02, 14 May 2012 (UTC)

At some time prior to the experiment it was feared that the loss of the delayed neutrons might result in a loss in damping of any power oscillations of the reactor. However, it was possible to demonstrate mathematically that the circulati on of the fuel tends to damp oscillations, and the operation of the experiment did not s how any tendency toward oscillations. [1]

Delayed-neutron fraction [2](p36)
Contributor Fission fraction Contribution to delayed neutron fraction
U-233 0.55 0.0014
U-235 0.23 0.0015
Plutonium 0.22 0.00046
Again not a null result, as the MSRE was low power density (big core) which kept most of the delayed neutrons in core. Denatured molten salt reactors, which your reference is about, also have such large cores. Such large cores have no issues with loss of delayed neutrons, but very compact designs would likely have. Whether this makes the reactor unstable remains to be seen; with sufficiently negative Doppler and coolant coefficients, it may not be a real issue. Siphon06 (talk) 14:05, 12 June 2012 (UTC)

Program Cancellation[edit]

I have moved the program cancellation section to the MSR article where there is more extensive materials to support this section of text. Of course, the MSRE was not cancelled but ran to a successfully conclusion. It was actually the follow-on effort that was canceled. MegaHasher (talk) 03:37, 3 May 2012 (UTC)

One Fluid and Two Fluid[edit]

We have two sections dealing with the historical ORNL one fluid and two fluid designs. If we want to include texts about modern one fluid or two fluid designs it might be best to use their own headings, in order not to confuse the modern with the old. MegaHasher (talk) 23:47, 3 May 2012 (UTC)

POV issue in headings; unbounded length[edit]

One important subject is the choice of subject heading in this article could lead to point of view biases, which is prohibited by Wikipedia. I would encourage editors to group texts into subject headings of bounded size, and to minimize bias. MegaHasher (talk) 18:30, 4 May 2012 (UTC)


Many of the References appear several times. There is method to do this more elegant - having the references only, with several links back. This will help to keep the list a little shorter.--Ulrich67 (talk) 23:24, 4 May 2012 (UTC)

Many of the references are from Thorium Energy Alliance conferences. As much as I would like to attend one maybe next year the best references are US government funded nuclear reports. You can quote them more extensively, and they lead you to more useful references. MegaHasher (talk) 04:16, 5 May 2012 (UTC)

There are a lot of low quality references, that do not meet the wikipedia quality standards. It does not help to give many of these low quality sources - this tends to make a hidden link list from the reference list. The slides or videos of conference talks and blogs are often highly biased and thus rather bad references especially for things like pros and cons.--Ulrich67 (talk) 16:54, 5 June 2012 (UTC)

TEAC Conference Minutes[edit]

Somehow what appears to be TEAC Conference minutes appeared as a section in this article. This section need to be re-organized, or reverted all together. Much of the content is unrelated to Small Modular Reactors. We can't have anything that starts with "Kirk Sorensen said...". Maybe best to just revert. MegaHasher (talk) 04:55, 5 May 2012 (UTC)

+1 This section about costs should be removed. There is no good ref to this, and other Refs. to costs more tend to say that costs of the reactor are similar to LWR. Cost estimates are always difficult, especially with a new technology and often tends to be biased. Even with conventional reactor costs sometimes increase by a factor of 2 and more.--Ulrich67 (talk) 15:10, 25 May 2012 (UTC)

Brayton Versus Rankine[edit]

Comparing Brayton cycle versus Rankine cycle in web search had a mixed result. Some studies showed Brayton as more efficient, while other ones had Rankine as more efficient. MegaHasher (talk) 20:44, 12 May 2012 (UTC)

Answer to MegaHasher:

The steam rankine cycle referred in the ORNL MSBR studies had an efficiency of about 44%.

Brayton cycles can be more efficient, but only when using closed gas, multiple reheat, intercoolers etc. The University of Berkeley work assumes such closed gas, multiple reheat cycles. At the ORNL MSBR operating temperature the efficiency is around 46%, but the temperature is higher than a steam cycle. At elevated temperatures >900 degrees Celsius, efficiency is over 55%.

Open Brayton cycles, such as today's natural gas burning gas turbines, are not more efficient unless extremely high temperatures can be attained, and even then are only slightly more efficient than supercritical steam cycles. However the advantage with a gas turbine burning natural gas is that the waste heat gas is very hot so can be used to power another, bottoming cycle, usually steam. This combined cycle allows up to 60% efficiency in the latest designs. — Preceding unsigned comment added by Siphon06 (talkcontribs) 13:31, 16 May 2012 (UTC)

Two Fluid Reactor Flexibility in Reactor Size[edit]

For a single fluid reactor the MSRE was only 8 mega-watts. That is already very small. The sentence about "breeding breakeven" refers to the breeding ratio, and could it be a duplicated point about breeding ratio? I am pretty sure it is false to suggest only a two fluid reactor can have flexibility in reactor size. MegaHasher (talk) 21:02, 18 May 2012 (UTC)

These two points are related, but not exactly the same. With the 1 fluid design the breeding ratio drops significantly if it gets smaller. The breeding break-even already needs quite a large unit (like 500 kg of fissile material - maybe 200 MW). For the 2-fluid design the breeding ratio does not drop much with smaller size. The MSRE (38 kg fissile material, low power density) is more like the inner core of a 2 fluid design, not a 1 fluid LFTR. So it is true that the single fluid design is less flexible in size, if one wants significant breeding - even if less than break-even. Some 2-fluid designs have difficulties with large units, but here using several smaller units is an option.--Ulrich67 (talk) 12:31, 19 May 2012 (UTC)
The US Small modular reactor program defined a small reactor as less than 300 MWe. The Fuji MSR was a 155 MWe design. Your example of a 200 MW design would be a small reactor as well. MegaHasher (talk) 18:08, 20 May 2012 (UTC)
Need a reference. MegaHasher (talk) 02:37, 22 May 2012 (UTC)
Wash 1097 (section 5.3.2, currently Ref. no. 27) gives a minimum practical size of about 1000 MW(e) (or a little less) - this is a design with about 1500 kg fissile material. Without removal Pa the power per amount of fissile material would be smaller and thus a lower power rating (more like 200-500 MW(e)) for the same size of core. This is not a sharp limit in size - it just gets increasingly difficult getting smaller. So the 1 fluid LFTR is limited to relatively large size. Very small breeding reactors just need a blanket to reduce neutron leakage.--Ulrich67 (talk) 15:04, 25 May 2012 (UTC)
The Fuji Designs have a relatively low power at something like 150-250 MW(e) (depending on the Ref. used, but it still uses quite a large amount of fissile material, like 1950 kg for the 250 MW(e) version, and even this just at break even. It is always possible to limit the power of a large reactor so a small reactor should be better defined as one with a small amount of fissile material, not from the rated power. In conclusion this means that the LFTR is actually less flexible in size than the LWR. So the point "LFTRs scale well" under advantages should better be replaced with some extra informations to the sections on the 1-fluid (only large units) vs. 2-fluid (preferred small).--Ulrich67 (talk) 18:12, 1 June 2012 (UTC)
I am not sure if the reduced breeding ratio quoted in Wash 1097 could be attributed to switching from 2 fluid to 1 fluid. The change from a 2000 MWe design to a 1000 MWe design could have done it too. This bullet item is probably a combination of breeding ratio and reactor size, but these items were already mentioned, which could be a form of double counting. MegaHasher (talk) 22:41, 1 June 2012 (UTC)
Reactor size still is an issue: If one does not want the possibility for small sizes as a positive feature of the 2 fluid (and 1,5 fluid) design, we should note it for the 1 fluid design as a design limit.--Ulrich67 (talk) 19:50, 4 June 2012 (UTC)
One of the smallest one-fluid design I can find is the FUJI-U3: [3] 200 MWe, breeding ratio 1.01, 30 year graphite life. MegaHasher (talk) 06:49, 5 June 2012 (UTC)
Though small in power this design still uses 1,5 t of fissile material. So it's something like a large core at low power density, needed to get good graphite lifetime and to avoid Pa removal. The ORNL 2-fluid design was 315 kg U233 and 250 MW(e) at a relative high power density. At a reduced power, to circumvent Pa removal and to improve core lifetime, this would be more like 50 MW. Already here they needed the complicated interleaving of core and blanket to make it that large.--Ulrich67 (talk) 20:27, 5 June 2012 (UTC)


The section Advantages describes some of the properties - not all are actually positive (the rather slow breeding from thorium compared to U238->Pu (about 10 times faster) is more a problem, than positive). Similar other points have both positive and negative sides to it or are just requirements to make the LFTR safe. Most of these points appear in some talks - but it is questionable if this belong in this article: the talks are given to point out the advantages, so they are highly biased sources (and they are far from sufficient quality to qualify as a reliable source). There just is no need make the article biased - this article is not about selling something, unlike some of the talks and videos.

It should be better to have a sections about things like fuel (could be mainly a link to thorium fuel cycle), safety-systems and waste. That have both the positive an negative parts. --Ulrich67 (talk) 15:53, 25 May 2012 (UTC)

There are some good stuff in the deleted material, but it needs to be summarized in a non-biased form suitable for Wikipedia. A generic subject heading like "Advantages" is generally inferior to a specific subject heading such as "Plant cost estimates", or "Energy unit cost comparison". MegaHasher (talk) 05:26, 1 June 2012 (UTC)
I agree that some information on costs may be useful. However it is rather difficult, to find a good source on this. The deleted part on costs was rather useless: highly biased and not at all a reliable source. Cost estimates are very difficult, even mature technique like PWRs. For the LFTR there are so many open questions (e.g. 1 vs. 2 fluid, type of reprocessing, safety requirements) that it is just to early for a serious estimate. The cost estimates for the fast breeders were also very much lower. So at best one would get something like ... claimed low costs, though it's to early for a serious estimate.--Ulrich67 (talk) 21:03, 3 June 2012 (UTC)

Under Advantages there is the point transparent coolant. Is this point really relevant ? This should only apply to the secondary salt (without fuel), and only in the hot liquid state. Water used in PWR is transparent too - so it's not really an advantage, just on par. As the list and the whole article is already on the long side, I suggest removing this small paragraph. --Ulrich67 (talk) 23:32, 9 July 2012 (UTC)

The section under advantages- safety about the temperature coefficient of reactivity seem a little to simplistic and optimistic. Newer, more detailed calculations (e.g. [] and [1]) show that the temperature coefficient is not negative in all cases - especially the ORNL-MSBR design often used as a basis likely does not have a negative temperature coefficient. Its only the coefficient for the salt itself that is negative - but due to the graphite the overall coefficient is positive (or at least not sure to be negative). So this design would not be intrinsically safe and self regulating, though not necessarily unsafe. The simple way to describe the influence of salt expansion is also not correct: In an under-moderated reactor (like the MSBR) removing salt from the core increases reactivity. The simple picture of less fuel salt means less reactivity is true for a small reactor where neutron leakage is important. In an under-moderated large core, less salt could mean better moderation and thus more reactivity. Thus the void coefficient can be positive too - a serious safety concern. So a large negative temperature coefficient is more a restriction to observe, but not a general advantage of a LFTR. At best one could say that it is likely possible meet this requirement, but this comes at a price, like reduced breeding. So this section needs editing - possibly moved outside advantages as a separate section (e.g. reactivity coefficients). The fist thing would be to correct the part on expansion of the salt.--Ulrich67 (talk) 15:39, 17 July 2012 (UTC)

The picture of the liquid FiLBe only shows, that the pure carrier salt is transparent. The picture under Uranium-233 shows, that at least the solid form with uranium is dark green. Melting likely will not make it transparent. Still there is no Ref. for the optical Inspection in the hot state: Even if transparent this would be hard to impossible - so I don't see any advantage from this. --Ulrich67 (talk) 17:48, 8 September 2012 (UTC)

Other Uses[edit]

I tend to agree that "Other Uses" should have its own heading instead of appearing under "Advantages". Again the TEAC3 reference is not that great because they are self published presentations. Article submitters should submit sections with good heading classification, in summary form, and specifically referenced. We as editors don't have an obligation to fix every borderline additions. In Wikipedia a section deletion needs no justification other than that section not meeting the published standards of Wikipedia. Also it is not useful for article writers to re-submit deleted section completely unmodified. At least use the talk page to find out what is wrong about it. MegaHasher (talk) 23:28, 1 June 2012 (UTC)

References for Talk Page[edit]

  1. ^ Ergen, W. K. (1957). "The Aircraft Reactor Experiment-Physics". Nuclear Science and Engineering 2: 826–840. 
  2. ^ J. R. Engel, etal., Conceptual Design Characteristics of a Denatured Molten-Salt Reactor with Once-Through Fueling, ORNL-7207, Oak Ridge National Laboratory 
  3. ^ Yoichiro Shimazu. "Current Situation of MSR Development in Japan". 


Currently there is a section "Ease of reprocessing". This should better called just reprocessing as reprocessing is not per se easy. If it would be so easy as sometimes claimed, it would likely be used for solid fuel too. --Ulrich67 (talk) 20:46, 5 June 2012 (UTC)

The reference given for the "very small" reprocessing plant still gives a size of the reprocessing units that is about 1/4 to 1/2 the size of the core itself. This is for the 2 fluid design - which makes reprocessing much easier than the more practical 1 fluid (or 1,5 fluid) design. In addition this is assuming a rather small throughput of 15 ft³ a day, of about 50 days cycle time for the core. So my conclusion from this rather old ref. would be more it needs a rather large reprocessing plant to reach 10 days cycle - possibly larger and more expensive than the rest of the hole reactor.--Ulrich67 (talk) 20:02, 7 June 2012 (UTC)
One Problem here is, that small or vary small is rather vague - it's the question small compared to what. With the reprocessing part it also very much depends on the frequency of reprocessing. Going from 10 days (needed for Pa removal) in the older designs to something like 100 days, reduces the needed throughput by a factor of 10. There are also several different suggested methods - and some early laboratory tests of some parts. So it may be to early to get a good estimate of the size. --Ulrich67 (talk) 12:12, 10 June 2012 (UTC)

Easy to control[edit]

Hi everybody. I'm new here and no native speaker. Translating LFTR into Polish. I find In solid-fuel reactors, it remains in the fuel and interferes with reactor control. under the Easy to control heading inconsistent with the next sentence. May I suggest to begin the next sentence like "Continuous LFTR salt processing in which Xenon-135 is removed, combined with the low reactivity..." etc? Pliftr (talk) 00:05, 9 June 2012 (UTC)

The problem is in the formulation with "this feature,..." - probably the sentence before that was added later and causes the confusion. I would suggest removing the sentence "In solid-fuel reactors, it remains in the fuel and interferes with reactor control" - there is not much new information here - most is said just 2 sentences before.
This article is not yet in a quality and stability really suitable for a direct translation. As you can see it is still frequently changing and contains some disputed parts and active discussion going on.-- (talk) 09:03, 9 June 2012 (UTC)
Alternatively one could also delete the last sentence of the point, as it only repeats other points already mentioned. --Ulrich67 (talk) 12:25, 10 June 2012 (UTC)
Yes, major editing requires thorough cleanup. It lacked probably also in "Low mobility of radioactivity" where "MSFR" remained.Pliftr (talk) 16:15, 10 June 2012 (UTC)

From waste to resource[edit]

This section contains a lot of wishful thinking: There is very little reuse of fission products in conventional reprocessing and the liquid salt form does not offer so much advantages. Most of the refs given are just for the properties of the materials. The 2 refs at the end really about use from fission products are rather low/no quality. Just a few weak points: Technetium-99 is actually a type of more problematic long lived waste - not valuable, though there is a very limited use to it. For separation the amount of actinides in the waste does not make a big difference, most of it is already removed in conventional reprocessing. The tricky part is to get the last few ppm out. So this section needs a cleanup or maybe removed altogether, as this is only a small side effect, and quite speculative.--Ulrich67 (talk) 20:33, 10 June 2012 (UTC)

There is only one low Quality source (company Website, giving this as possible future plan). Some sentences are even copies from this site and thus would likely be URV. Even as a Speculation this does not make much sense: The LFTR produces less (about half compared to other reactors) Xe-136. Neodymium is expensive because of the difficult and waste producing separation - so separation from the radioactive waste is extremely expensive (likely more difficult and expensive than the PUREX process). Where the noble metals end up is not clear - its only clear that they will not end up in the salt. Already the nickel filter is speculation. So reclaiming these elements is likely challenging. Getting these elements from LWR Spend fuel is likely simpler. Bismuth 213 is just a decay product of U-233. Technetium99m can not be used directly from the reactor, but needs the decay from Mo-99 to get reasonable purity and a little more time. So much of the current text is of no real use and I don't see a reason keeping it.--Ulrich67 (talk) 20:48, 22 October 2012 (UTC)

Energy density[edit]

Hi ShotmanMaslo, I'm new, not a native speaker and translating the LTFR Wiki article to Polish. New also to Wiki. Please tell if I should better use "talk" at the article page or may I ask questions to someone like you? I'd appreciate every advice.

Well, since I am here already see my question:

I find "energy density" term in the "Economy and efficiency" section. It reads "The energy density is millions of times higher than any fossil fuel..." In my opinion such strong claim deserves a link to the Wiki Energy density article. Sadly thorium has only a minor remark there. Try to look also at the Polish version of the article and you will see that more detailed information appears in the table here (I added short English translation)

Fuzja deuter-tryt (fusion) 337 000 000

Rozszczepienie uranu (100% U-235) (U fission) 88 250 000 1 500 000 000 (MJ/L)

Naturalny uran (99,3% U-238, 0,7% U-235) w reaktorze powielającym (fast breeding) 24 000 000

Uran wzbogacony (3,5% U-235) w reaktorze jądrowym (Enriched U in reactor fission) 3 456 000

Naturalny uran (0,7% U-235) w reaktorze jądrowym (natural U in ractor fission) 443 000

It makes good comparison I think. But thorium is absent here as well.

Would you share my opinion that thorium entry should be added to both articles? What are the corresponding MJ per kilogram and MJ per litre values?

Regards Maciek (talk) 16:13, 15 June 2012 (UTC) — Preceding unsigned comment added by (talk) 16:09, 15 June 2012 (UTC)

Indented lineHi.

You can use the article talk page I think. If you find a good reference for thorium energy density, then it should be added, also into the english LFTR article. I have not found specific figures, but it would probably be comparable to U-238 in fast breeder reactors (24 000 000 MJ/L).

I'm deep in my translation and making some occassional remarks on the run. Can anybody help and find the needed values for me?

Pliftr (talk) 18:03, 15 June 2012 (UTC)

GA Review[edit]

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

Reviewer: Grandiose (talk · contribs) 18:58, 18 June 2012 (UTC)


This article is not ready to be a Good Article, for many reasons. You may wish to peruse WP:What is a Good Article? or look through other articles at WP:GA, but I'll my best to explain what the problems are.

  • Per WP:Verifiability, every controversial statement needs a reference. This is pretty much every statement, unless it is patently obvious. This means that almost all of the article requires a citation. There are far too few references provided in the article at the moment.
  • Citations require details that allow others to verify the statement. Given than weblinks sometimes break, this means providing things like the page's title, date, author, work and publisher. If you use a template like {{cite web}} for web links, then the fields should provide a guide as to what it is necessary to include (not all the fields, but at least some).
  • Layout. The long-list format doesn't work very well. If you look at WP:LAYOUT, then you will see that bullet points are only suitable for lists of short items, unlike in the article at current. Instead, the sections should be divided into groups and each point presented in a paragraph.
  • Prose. There are some problems, such as fuel / breeding and conversion to an insoluble form such as a glass, could be desirable. There are also some non-encyclopedic parts such as An excellent detailed technical description of the 1970s development status and knowledge of the molten salt breeder reactor (MSBR) that the ORNL program was working on is available online in a single large document.. I suggest a copyedit from the Guild of Copyeditors, once you've seen to the other problems.
  • Lead. Bit difficult to follow; doesn't make much mention of the advantages/disadvantages which occupy most of the article. It's the part which needs to be best explained to the lay reader.
  • Following on from this there is some attempt at an accessible introduction, but it's still very hard to understand. The explanation is basic in some respects, but jargon remains difficult for the lay reader.
  • Images: mostly fine, although File:Lwrvslftr2.png looks a bit suspicious. Sub-images are included, but their copyright status isn't clear.

Feel free to renominate the article once these issues have been addressed. Grandiose (me, talk, contribs) 18:58, 18 June 2012 (UTC)

Less activated waste ?[edit]

Is there really less activated waste with the LFTR ? The first question here is less than what ? The obvious choice here would be the normal LWR. To me this not at all obvious that the LFTR causes less activation, though it is hard to compare because there is no definite design, but a variety. Usually the LFTR has quite a lot of graphite in the moderator (e.g. about 300 m³ every 4 years in the ORNL MSBR design), then there is the reactor vessel, the whole primary circuit and much of the reprocessing. Recycling the graphite moderator is likely not possible, since the LFTR needs a high quality graphite. So my estimate would be that the graphite alone would be more activated material than with normal LWR operation. Anyway the amount of activated material is more an economic issue - less safety relevant. --Ulrich67 (talk) 16:55, 25 June 2012 (UTC)

Dr. David Leblanc has figures on parasitic captures in LWRs and CANDU, compared to DMSR. They are 22%, 12% and 5% respectively. Graphite absorbs very few neutrons compared to the fuel claddings used in LWRs and CANDUs, and the undermoderated region results in reduced neutron leakage. With less metal inside the core, and no metal cladding that must be replaced with new fuel every year or two, the amount of activated waste is much reduced.

Siphon06 (talk) —Preceding undated comment added 13:54, 2 July 2012 (UTC)

This still is only a comparison of the neutron loss. The biggest neutron loss in the LWR is conversion H to D, which is not activated waste. The CANDU has quite a lot of internal structure (pressure tubes) - so it is not obvious that in the LWR, the neutron loss other than to H is more than 5%. It can be still possible that one type of LFTR can create less activated waste, but this is still unclear how to compare - by volume, by activity, by radio-toxicity or how else. In any way this would need a Ref. and preferably a clearer formulation. --Ulrich67 (talk) 19:41, 2 July 2012 (UTC)

The CANDU has 12% parasitic captures and almost no H (in stead has D2O), whereas the DMSR has 5%. Therefore the CANDU has much more neutron capture than the DMSR, even though graphite absorbs more than heavy water. Which is proof that there is less activation in the LFTR. — Preceding unsigned comment added by (talk) 12:17, 6 September 2012 (UTC)

So we have a low quality reference that shows that a CANDU reactor has more parasitic neutron loss than a proposed LFTR. This still is only a indirect hint that makes the claim likely. With the standard LWR the question is still very open: The Shippingport LWR was able to reach breeding in the Th-U233 cycle: this indicates a very low loss of neutrons less than about 12%, including the loss to H2O). I see this as an indication that there is not much loss to the structural material. So the claim is far from obvious and needs a much better reference.--Ulrich67 (talk) 16:43, 6 September 2012 (UTC)

Advantages - Economy and efficiency[edit]

This section needs some cleanup: The argument of more efficient fuel use is repeated several times, with sightly different aspects. There also seems to be NPOV issue, giving too much emphasis to some rather unimportant points (e.g. once the price for the Th is negligible low, the details don't matter any more). The ref. given to show that there are enough natural resources is rather old, and for Bismuth specified in many reprocessing schemes it even states that that there will be a shortage (even by about 2000) - for the whole point it is questionable if we need this point here at all. It is more a reply to earlier text that questioned the availability of Li or Be. The points of efficiency in fuel use and LFTRs are cleaner assumes 100% efficient reprocessing. As far as I found reprocessing is significant less efficient. The last point (from waste to resource) has only a very week source (filbe web page) for the main point - the other refs. are just for more or less obvious details. Finally there is the general problem with the whole "advantages" section: it is not clear what to compare. There are different suggested LFTR designs and different current conventional reactors and fuel cycle options. So it may be better to put the whole economy part outside, and formulate it in a NPOV way with positive and negative aspects in one section, even if it is difficult as most of the available sources are primary sources and thus likely biased.--Ulrich67 (talk) 20:24, 1 August 2012 (UTC)

Yes, POV is an issue and I have restored User:nneonneo's Advert tag. Also agree that, per NPOV, we need to have discussion of positive and negative aspects integrated together. Johnfos (talk) 00:15, 2 August 2012 (UTC)

POV and associated tags[edit]

I notice in the above comments that the issue of POV or non-neutrality has come up quite a bit with this article and I would agree that the article is not balanced, in that it advocates the use of the LFTR.

In terms of the layout, the recent GA reviewer has said that the long-list format doesn't work very well. If you look at WP:LAYOUT, then you will see that bullet points are only suitable for lists of short items, unlike in the article at current. Instead, the sections should be divided into groups and each point presented in a paragraph. Moreover an integrated discussion is to be preferred to WP:Pro and con lists.

As the GA reviewer said, per WP:Verifiability, every controversial statement needs a reference. This is pretty much every statement, unless it is patently obvious. This means that almost all of the article requires a citation. There are far too few references provided in the article at the moment. Unsourced material may be challenged and removed at any time.

WP:Linkrot is an issue for many of the references. Citations require details that allow others to verify the statement. Given than weblinks sometimes break, this means providing things like the page's title, date, author, work and publisher. If you use a template like {{cite web}} for web links, then the fields should provide a guide as to what it is necessary to include (not all the fields, but at least some).

A smaller number of high quality external links should be used, avoiding advocacy links.

I have added some tags which reflect these comments and hopefully should provide guidance. Johnfos (talk) 00:18, 2 August 2012 (UTC)

A agree with changing to a more integrated discussion - I already started, by moving the part on reprocessing outside. However this part needs a major cleanup or rewrite, not just more references. For good reasons here much less information is available, and finding a neutral point position likely causes some discussion. Other topics that may deserve a separate section may be waste, economy, and safety - with pros and cons. So we may not need the section advantages any more, and the Design challenges could be reduced to something like research to do.
Just small changes and additional Refs. for the tagged point will not solve the structural problem of article. For now the references with just weblinks is not good, but still one of the smaller problems - this could be fixed when a reasonable stable version is there. A bigger problem is that some of the sources are of low quality, especially the slides an videos from conference talks. --Ulrich67 (talk) 17:23, 3 August 2012 (UTC)
Agree that changing to a more integrated discussion is the main thing, and thank you for making a start on this. Also agree that some of the sources are of low quality, especially the slides an videos from conference talks, and these need to be upgraded or removed. Johnfos (talk) 21:31, 5 August 2012 (UTC)

advantages - slow heatup[edit]

The references given for the point slow heatup show data on the specific heat capacity, not much more. However the specific heat capacity is only one point, and the difference is not that big, comparing to a classical LWR reactor: The fuel salt itself may have a slightly higher heat capacity, but there is much more moderator than fuel in both cases - as the LFTR tends to be more compact, expect it to have the smaller capacity. Anyway, the difference and advantage of the LFTR is more in the larger allowed rise in temperature: In a water cooled reactor only limited temperature excursions are allowed before the pressure rises to much. The salt temperature cold rise several 100 K, before immediate catastrophic occurs. The amount of heat that can be absorbed is specific heat capacity * mass * temperature rise. The LFTR wins because of the last factor. So at best this point is unclear and missed a ref. for something else than details. --Ulrich67 (talk) 21:53, 26 September 2012 (UTC)

Unreliable Sources[edit]

There are still some unreliable sources: Slides from talks are usually self published work. In addition they may give a very simplified often exaggerated view with the talk itself missing. In this way videos may be a little better, but still this is not a good source. I don't think we should rely on such sources. At least we should keep them marked as less reliable. The videos are also candidates for future dead links. --Ulrich67 (talk) 22:23, 15 October 2012 (UTC)

I wrote a lot of the initial article, and I have some suggestions for sources. The best references are probably the U.S. government reports. The basic references for the MSRE, the last real laboratory research on LFTRs, are "The Use of Thorium in Nuclear Power", WASH-1097 (1969) and H.E. McCoy, and B. McNabb, Intergranular Cracking of INOR-8 in the MSRE, ORNL-4829 (1972), Technical Report, Springfield, VA, USA. I believe both are on the web at and they're also available from U.S. National Technical Information Service, U.S. Dept. of Commerce. The 1969 report, WASH-1097, discusses the MSRE, and seems to indicate that it was killed because of corrosion. ORNL-4829 summarizes the successful corrosion research completed in 1972. Most of the "unreliable" web sites are discussing implications of these two reports. Ralph Moir has published a number of more recent, peer-reviewed papers, and made them available at One of his most interesting papers is: Moir, Ralph W. "Cost of Electricity from Molten Salt Reactors (MSR)." Nuclear Technology, 2002: 138 93-5; He and Edward Teller also published a survey article about LFTR advantages. One of the best ways to cope with LFTR wastes is to convert them to iron-phosphate glasses, which are less soluble in ground water than borated glasses like Pyrex. A good reference for that is: Darryl D. Siemer, "Molten Salt Breeder Reactor Waste Management", Nuclear Technology, volume 185, no 1, January 2014 p100-108. (This is more laboratory work.) Ray Van De Walker 06:24, 11 January 2014 (UTC)

Excellent heat transfer[edit]

Under Advantages there is one Point "Excellent heat transfer". Here the ref. ORNL-TM-2006-12 (currently number 51) does not support the claim that the salt gives better heat transfer than water. It gives the opposite: water being better than molten salt (e.g. lower figure of merit), even for pure Filbe, and more for other salts listed. The comparison is difficult anyway, as water and the salt can hardly work at the same temperature, and the salt may allow for a higher temperature difference. However if the temperature is lowered, the viscosity of the salt increases quite fast and makes heat transfer more difficult at temperature much below 700°C. The direct comparison of thermal conductivity and volumetric heat capacity is somewhat misleading - viscosity and density are also important factors, this time favoring water. Also the addition of ThF to the salt is expected to have a negative influence (higher viscosity, higher density, less thermal conductivity and lower volumetric heat capacity).--Ulrich67 (talk) 21:50, 3 December 2012 (UTC)

Polish translation of the Wiki LFTR article uploaded[edit]

I have finished my Polish version of the LFTR article in the end and uploaded it to the Polish Wiki as "Reaktor torowy na ciekłych fluorkach". This is my first Wiki article. It has been reviewed and is now available for the Polish readers. Please advise if I may add interwiki links

en:Liquid fluoride thorium reactor to the Polish version and

pl:Reaktor torowy na ciekłych fluorkach to the original article?

Pliftr (talk) 18:12, 30 May 2013 (UTC)

Disadvantages Read Like Advantages[edit]

I just read through this article, and I wanted to post some feedback. It seems to have a large base of contributors, which is good. However, for how long the article is, it could certainly be more concise. Specifically, each disadvantage listed has one or more counter-arguments listed for how that disadvantage could be overcome. It is really quite tedious to read both subsections of 'Advantages' and then get into the 'Disadvantages' only to be reading a third section of advantages. It certainly does not seem to be written even-handedly. (talk) 22:02, 7 June 2013 (UTC)

That's basically because a few of the "disadvantages" actually belong in the advantages section. When someone with a lay education in the nuclear field hears the word "nuclear" or "uranium", they begin to worry that this could lead to things like nuclear proliferation. However, in this case, it is rather difficult to use this technology for nuclear weapons (continuing with the example), so much so that it effectively can not be. Which is why it is an advantage (and not a disadvantage as a layman may think it is). Former nuclear engineer → — al-Shimoni (talk) 01:20, 2 July 2013 (UTC)
Using long lists of advantages and disadvantages is problematic since things are usually not that simple, that one has clear disadvantages / advantages. Especially for points that are problematic and thus disadvantages at first, there are special designs needed to more or less deal with the possible weaknesses - in some cases causing new problems. Some topics like proliferation are just not that clear - there are both pros and cons, with different sources giving more weight to one side or the other. So these controversial parts should better have a separate section outside the pro and con list.--Ulrich67 (talk) 20:55, 26 July 2013 (UTC)

Low corrosion, long lasting materials[edit]

There is this point under Economic advantages. There is a Ref. given - however the contend of this section is not supported by the two Refs. - more of the opposite: corrosion is still an open question and more research and tests are needed. So I Suggest removing this point all together - most of the corrosion problem is already handled better further down under disadvantages (with the same Refs.). The numbers given for the replacement graphite are also of rather limited value. They are rather old cost estimates of the new material only - the bigger issue with graphite replacement is the waste and downtime and provisions needed to do the replacement.--Ulrich67 (talk) 11:41, 22 June 2013 (UTC)

The MSRE had no problems with corrosion from the salt. This is documented in WASH-1097 (1969), the MSRE's main research report. It had problems with a tellurium fission product slowly dissolving the grain boundaries in the nickel alloy, "Hastelloy-N." The corrosion was slow because there wasn't much tellurium in the salt. The tellurium corrosion was researched and fixed after WASH-1097 was published, which I think may be causing the confusion. The research showed that a bit of niobium in the hastelloy fixes it. This is discussed in a later research report, McCoy, H.E., and B. McNabb. "Intergranular Cracking of INOR-8 in the MSRE," ORNL-4829 (1972). Technical Report, Springfield, VA, USA, or An authoritative publisher is: U.S. National Technical Information Service, U.S. Dept. of Commerce.
The summery (p. 170-173) of ORNL-4829 confirms that there was some corrosion in MSRE. Weather this corrosion is serious or just superficial is hard to say: it's just a few mils deep most of the time, but cracks in a brittle material are serious even if small. At least ORNL took it rather serious and did quite a lot of follow up. Still they say even more test are required to be sure. There was some improvement after wash-1097, but far more research is needed and this is far from the level of confidence that exists in water based reactors. So adding niobium may help, but it is not sure the corrosion problem is solved.--Ulrich67 (talk) 19:15, 12 January 2014 (UTC)

Destruction of existing long lived wastes[edit]

This point under advantages is a little off topic for the LFTR: It may be possible to use some SNF components as a fuel in a MSR, but not in LFTR as described in this article. Also this is only a still rather vague suggestion with may open points. As the LFTR as a thermal reactor with only marginal negative reactivity coefficients adding extra problematic elements is hard (it may work in small non breeding MSR with better safety) and the buildup of MA is no better (likely even worse because of slightly harder spectrum) than in a LWR. Also the LFTR has very few spare neutrons, and adding waste with MA tends to reduce breeding even further. The real option for transmutation of MA is using a fast MSR , possibly even accelerator driven - this is rather different from a LFTR. So if at all (because this are just plans with may open points) this point should go to the more general MSR article.--Ulrich67 (talk) 08:05, 27 July 2013 (UTC)


This whole article makes no reference to an estimate of the costs per kwh. Surely this is the most important point of any discussion of alternative energy sources!? Let's make that happen! ;-) (talk) 10:50, 5 August 2013 (UTC)

The main developement is rather old (late 1960's). At that time there was a cost estimate at cost comparable to a conventional nuclear power supply. Due to may still open questions this is a rather crude estimate. In addition regulations have changed since then, and chemical reprocessing turned out to be much more expensive for solid fuel - so the old numbers are rather outdated too. It may be worth having a separate section on costs - though the conclusion is more ore less that the final costs are unknown and estimates are difficult so early in development. The difficulty is to find a current unbiased source.--Ulrich67 (talk) 10:01, 10 August 2013 (UTC)
Ralph Moir wrote a published, peer-reviewed article estimating LFTR costs. It was $0.038/Kwh, vs. $0.041 for dirty-style coal plants of the same era. This was based on comprehensive cost estimates done at Oak Ridge National Labs, which designed a full-sized LFTR power plant. This means that potentially they're cheaper than anything else out there. The article is well-known to LFTR aficionados, who often quote the conclusions without attribution. See: Moir, Ralph W. "Cost of Electricity from Molten Salt Reactors (MSR)." Nuclear Technology, 2002: 138 93-5, or see, accessed 2014-1-10. Ray Van De Walker 05:14, 11 January 2014 (UTC)
The article of Ralph Moir only adjusted the old numbers for inflation. Doing this old, crude estimates don't get better this way - they are just outdated. The French programs suggest that fast reprocessing as planed in the MSBR is likely not feasible - thus too expensive to be competitive.--Ulrich67 (talk) 21:46, 7 March 2014 (UTC)
I agree with you on the prohibitive cost of MSBR-style processing. Do you have a reference for the French cost estimate/feasibility? markmassie (talk) 18:28, 8 March 2014 (UTC)
One ref. ist currently Ref 43 in the article. Slightly more details this in this article from the same group [2]. There is no detailed cost estimate (it's just to early to give serious numbers), just mentioning that fast reprocessing may not be feasible and assuming a 6 mouth cycle as realistic. The best I could find as a cost estimate were some estimates on pyro-processing metallic fuel for a fast reactor - somewhat similar, but not that much. These numbers would also make a 10 day cycle to expensive and something like 6 months realistic.--Ulrich67 (talk) 19:44, 8 March 2014 (UTC)

Passive decay heat cooling[edit]

Under Advantages there is this point. However for new nuclear designs passive emergency cooling is more or less a requirement. On first sight the high temperatures may help designing a passive cooling - however, the only ref. given for this section essentially only gives crude first ideas and at the end says that more research is needed to validate and understand these things. The need to limit cooling (to prevent uncontrolled salt freezing) and the requirements not to use water and keep oxygen out can actually make passive decay heat cooling more difficult than in a water based system. At least ORNL used a quite intricate active cooling system for the salt storage system of the MSER. So far the given Ref. is more supporting the lack of a proven concept for passive cooling - this is definitely not an advantage. So unless someone finds a good Ref. on this - this point should be deleted or even moved in revised form to difficulties.--Ulrich67 (talk) 18:07, 30 December 2013 (UTC)

The advantage is that the fluid decay products can be drained from the heat-conserving reactor to a scram tank, which can passively emit large amounts of heat. For example, reactors are generally large squat cylinders with minimal surface area. A large LFTR's scram tank can be an array of pipes or hollow plates with much greater surface area, and they can be submerged in meltable salts or water to diffuse the heat. Further, the MSRE had a clever passive method to self-scram, by blocking the drain with frozen salt. If the cooling failed, the reactor would melt the plug and self-scram. Solid-fueled reactors of whatever type can't do these things. References... WASH-1097, the official report, refers to the MSRE's drain tank, but does not discuss its geometry and cooling characteristics. Ray Van De Walker 05:34, 11 January 2014 (UTC)
Wash 1097 - does not mention passive cooling as this was not a requirement at that time. Some other refs mention passively cooled tanks to be planed, but don't give any details. The freeze valve is a different point, and just a fist step (not needed in other reactors) in decay heat cooling. The Ref. we have in this section suggests that development of passive cooling is still open. This may not be a big deal, but still its an area that needs development - so it's to early to say how good passive cooling works. In comparison, new LWR designs usually include a well developed passive decay heat cooling.--Ulrich67 (talk) 21:28, 7 March 2014 (UTC)

... Times Greater Than ...[edit]

The fragment "four times greater abundance in the earth's crust than" appears in the article. This is ambiguous. If it is five times as abundant as, then let's say so. If it is four times as abundant as, then let's say that.

The fragment "20x smaller than" also appears. What the hell is that supposed to mean? 1/20 as large as?

Jack Waugh (talk) 22:27, 23 April 2014 (UTC)