Talk:Molten salt reactor

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Protactinium removal[edit]

I'm new to Wikipedia, so tell me if new discussion topics go at the beginning or end of the talk page. The article statement "When optimized for breeding, thorium breeder reactors require on-site reprocessing to remove Pa-233 from the breeding blanket so it can beta decay to U-233 instead of neutron capture to U-234." is true, but another favored design target is unity breeding, without Pa removal, increasing the U-232 contamination via Pa-233 (n,2n) --> Pa-232 --> (beta decay) U-232. This lowers the complexity and cost and increases proliferation resistance; fissile startup material can be obtained from other sources than LFTRs producing excess U-233. Should we add a sentence like "An LFTR with no Pa-233 separation reprocessing can breed enough U-233 to sustain itself and increase U-232 contamination and proliferation resistance." —Preceding unsigned comment added by Robert Hargraves (talkcontribs) 19:09, 29 January 2010 (UTC)

  • New Discussions usually go at the end of the page. I'm indifferent as to your question. Personally, I think that that is a level of depth that could best be split off to another article such as "possible molten salt reactor fuel cycle management" or such, with a summary in this article. I think this article is getting a little too technical and long. Lcolson (talk) 21:00, 29 January 2010 (UTC)
The question of Pa removal is rather specific to the thorium breeding reactors. There is a separate article (LFTR) on this. So we may not need so many details here. It depends on the power-density, whether Pa removal is not really needed. At low power density the Pa concentration stays low, and breeding is still possible - only the doubling time increases, because more fissile fuel inventory is needed. --Ulrich67 (talk) 20:02, 6 June 2012 (UTC)

Molten salt[edit]

What is a molten salt ?. Can any give soma examples ?. And an inert metal ? Thanks in advance --HybridBoy 13:34, 22 May 2007 (UTC)

Just what it says: Salt so hot it melted and is a fluid. (Yes, table salt melts; in a gas flame it vaporizes.) A picture of the molten salt is here. The most similar substance in every-day life is water, which is likewise an ionically-bonded substance that forms a polar fluid. Like water, a molten salt dissolves a lot of things easily, and conducts electricity pretty well. Because of these two traits, it can get pretty corrosive. Water (and molten salts) carry heat away pretty well (in fact, the specific heat is similar). A big difference: The BeLiF carrier salt mixture melts at 346C and vaporizes at 1400C! So, the liquid will burn one's skin something like molten lead or a soldering iron. Very nasty. 346C is not nearly hot enough to visibly glow, however. The colors are different: melted BeLiF is a clear, rather pretty blue-green fluid, about the viscosity of... water. It also has a meniscus like water, because it has similar inter-ionic forces. Unlike water, it shrinks when it freezes. Fluorides and Beryllium compounds are generally poisonous, so don't eat it. Hope that helps. Ray Van De Walker 02:09, 1 June 2007 (UTC)
Inert metal? See galvanic corrosion. Generally an "inert metal" is one that's "more noble" so that it doesn't dissolve in the presence of other metals that are touching conductive solvents. Classic examples are Gold, Platinum, maybe Nickel and somewhat copper. Ray Van De Walker 02:09, 1 June 2007 (UTC)

Working fluid vs coolant[edit]

The article currently states that the working fluid would be a molten salt, whereas it is in reality the primary coolant that is a molten salt. The working fluid (the fluid used to convert heat into work in the plant's turbine ) would most likely be light-water, or possibly helium in VHTR designs. It appears very unlikely that the reactor would use a salt as a working fluid since the working fluid would have to be boiling for the turbine to achieve a high efficiency ( and you really don't want a boiling salt as primary coolant ). 02:04, 18 September 2006 (UTC)

Most likely, in order to achieve the most efficiency (~50% carnot) the so called "work fluid" would be a supercritical CO2 gas in the special Co2-compatible high efficiency turbine. Whereas the coolant indeed would be a molten salt like a LiF-BeF2-ThF4 salt, but certainly not boiling, only molten.--Dmitri 152 (talk) 23:56, 25 July 2016 (UTC)


Could we have some references on the corrosion issues with the Flibe environment? I've looked for references to problems encountered during the live run of the MSBR experiment at Oak Ridge, but from everything I've read they didnt encounter any of these issues during the years that they ran the reactor.

Indeed from a Usenet post several years ago, Bruce Hogolund adressed these concerns, and the corrosion issues were due to tellurium fission products reacting with the Hastelloy-N rather than any corrosion due to Cr migration by itself:


As for corrosion of the pipes & reliability; an excellent question, as a leak is the only real accident a MSR can have. Hastelloy-N was chosen & represented a large part of the early research on the MSR, due to its total compatability with the salt up to ~700 C; thus the limit on its operating temperature. You can go higher, but then the corrosion rate rapidly rises from unmeasurable at 700 C. Of course some people unfamiliar with negative temperature control then question what happens if the temperature were to rise. With a MSR, the only way to increase the temperature is to add more fissile fuel because the amount of fissile determines the outlet temperature of the salt due to its total control via its large negative temperature coefficient. So it can not get too hot unless you add hundreds of kilograms of very expensive fuel to the MSR & never look at the output temperature guage!

There was one (& believe it or not, only one) surprise during the entire MSRE operation, and this was not at first detected due to its subtlety; the tellurium fission product disolves the chromium from the surface of the Hastelloy-N. This was noticed when Hastelloy-N samples, that had been in the MSR during its entire operation were stress tested (pulled apart) & it was noticed that there were tiny cracks (>0.1 mm) in the surface. This minor problem was later solved on 2 fronts: improving the alloy (Hastelloy-N is now modified with 1-2% titanium and/or niobium & is usually called "Titantium modified Hastelloy-N", catchy, isn't it! } & by maintaining the UF4/UF3 ratio (whose explaination are somewhat complicated, and better discussed in the reference below). --[unkown]

--- Many of the corrosion issues I discused were fixed by placing a Be rod in contact with the solution to drive down the electrochemical potential of the solution thereby negating many of the corrosion issues. I wrote most of this very quickly, and many of the things arn't applicable to the MSRE which used flibe. Using other salts would bring this problem back though, but for the sake of simplicity I think the whole article should be rewritten, especially the technicological issues section. I wrote that section when I was researching some other molten fluoride corrosion issues at temperatures in excess of 800C and they kinda crept in, mainly because they haven't solved the problem yet for flinak, however there are several ideas. I have lots of references on the ARE, MSRE, and other molten fluoride and chloride reactors, but I see no point in adding 100 plus references for an article that is a generalization. FLIBE may not be used in all molten fluoride systems, nor even a fluoride, which is why the technological issues thing included corrosion. For a reference here, see reference 2 by W.D. Manely, it is one of the more readilly available references, from what I understand he was a big wig in the MSR development community for a while. If you disagree, ask for a more pointed reference (i.e. molten fluoride corrosion, temperature driven mass transport, etc...). But I caution you, most of the references you must find offline as they are government reports, or were in journals and are copyrighted. The few online sources of info I've found usually aren't all that good. I looked at Bruce Hoglund's website and think there may be the potential for POV from him, refering to published ORNL work would be much better. I'll try to leave some of the more relevent sources below. The national lab abbreviation is first, followed by the report number (I think). Feel free to change some of the things, I know its not that good now, I can always change them back if I disagree, but I won't as long as it improves the article. Lcolson

ORNL-5694: 1981-01
Comparative Evaluation of Pebble-Bed and Prismatic-Fueled HTGRs
ORNL-5176: 1977-02
Engineering Tests of the Metal Transfer Process from MSBR Fuel Salt
ORNL-4829: 1972-11
Intergranular Cracking of INOR-8 in the MSRE
ORNL-2387: 1958-02-04
Aircraft Nuclear Propulsion Program: Quarterly Progress Report for Period Ending September 30, 1957
ORNL-TM-8298: 1982-12
Thermal-Convection-Loop Study of the Corrosion of Fe-Ni-Cr Alloys by Molten NaNO3-KNO3
ORNL-TM-5783: 1977-05
Compatibility Studies of Potential Molten-Salt Breeder Reactor Materials in Molten Fluoride Salts
ORNL-TM-5325: 1976-04
Evaluation of Alternate Secondary (and Tertiary) Coolants for the MSBR
ORNL-TM-4286: 1972-12
Alloy Compatibility with LiF-BeF2 Salts Containing ThF4 and UF4
ORNL-CF-60-12-111: 1960-12-13
Homogeneous Molten-Salt Reactors


I think that this article should be broken into several sections to avoid confusion.

one on the molten salt reactor with fuel bearing salt, the second on the molten salt reactor which uses the salt for coolant only. Finally, the ARE and MSRE should get their own sections, or their own articles. Lcolson

corrosive fluoride salts?[edit]

What's that comment about the dangers of floride salts? No molten fluorides are used "to extract aluminium", a fluoride (kryolithe) is used to get the melting point of aluminium oxide down for the electrolysis. This is done at higher temperatures than 700°C in graphite vessels, and they don't burn down. Mentioning the oxidizing power of fluoride is comparable to calling sodium chloride aka table salt toxic, because it contains chlorine.

This second paragraph of "technological" issues is better revoved altogether. --[unkown]


lets go through the points in this paragraph one by one.

The primary reason this concept has not taken off relates to the corrosion issues

Salts with any moisture or oxygen in them lead to rapid corrosion... especially in Ti, Al, and Cr containing metals.
Well, several issues with this: 1. Hastelloy-N is mostly nickel; 2. Oxygen is removed from MSRs by a helium sparge. 3. The MSR program at Oak Ridge was cancelled to focus the budget of uranium fast breeders. Ray Van De Walker 04:58, 24 July 2011 (UTC)

difficulty with working with highly radioactive fluids

The salt will likely have a fair amount of tritium in it from the lithium, but this is a trait shared by almost all cooling fluids except for maybe helium
Well, actually, in the MSRE, the salt was a Lithium Fluoride/Beryllium Fluoride mixture. The Lithium was isotopically purified to almost perfectly pure Lithium 7 so that it would not absorb neutrons and make tritium. A tiny amount of Tritium is produced by other processes, but the unmeasureably tiny amounts of hydrogen fluoride in the MSRE were removed, with Xenon and other gaseous wastes, by a helium sparge in the pump bowl. The proof is that no HF corrosion was observed, despite a careful search for it. Ray Van De Walker 04:58, 24 July 2011 (UTC)

the added expense of having to heat all piping prior to start-up

this and refueling is likely to be the largest problem of the concept, all those heaters for the piping will be expensive evin if they are only needed during start-up and shut-down and for maintenance
Heating the piping is cheap. All it takes is an electric heater and a closed cell. Refuelign is also cheap: In the MSRE they dissolved UF4 in the salt. Ray Van De Walker 04:58, 24 July 2011 (UTC)

lack of industry support

What company would want to produce this if they loose their fuel manufactering business. Also, why compete with eixisting technology which doesn't have the monitary risk.
This is a live issue, agreed. Ray Van De Walker 04:58, 24 July 2011 (UTC)

and lack of government support.

The DOE has stated that while the MSR is a gen IV concept, it is not being actively researched in the US
Also a live issue. However, the rigidity and expense of the NRC licensing procedures are even more important. Ray Van De Walker 04:58, 24 July 2011 (UTC)

Fluoride salts can be extremely corrosive,

This is just restating the already mentioned stuff and could be taken out
Well, it's also not true about Hastelloy, either. Ray Van De Walker 04:58, 24 July 2011 (UTC)

in fact, molten fluorides are used in the aluminum industry to aid in the extraction of aluminum,

Cryolithe (Na3AlF6, sodium hexafluoroaluminate.) I may be wrong, but this looks like the chemical composition of a salt to me. Also, unless the term solvent is misused in that article, it appears correct how it is stated above (i.e. aid), although it also appears to be used as a fluxing agent.
off topic. Ray Van De Walker 04:58, 24 July 2011 (UTC)

and fluorine is a better oxidizer than oxygen.

The molten salt will have to be clean to be used, a process which is neccessary to avoid corrosion issues. Fluorination is the only process I know of that can do this, and this requires fluorine gas. If there is excess free fluorine in the system afterwords, this could react with various metal constituents in the alloys.
The MSRE's salts were chosen to be self-buffering to a large extent. In particular, the UF transitions between UF3 and UF4. The normal way to control the reactors' oxidation (i.e. the titer of free fluorine ions) was to dissolve small amounts of beryllium in the salt by stirring it with a beryllium rod. Ray Van De Walker 04:58, 24 July 2011 (UTC)

Another issue for the MSR, at least for the designs that rely in fuel dispersed in graphite, is that the fuel-salt must be a liquid during refueling.

this is big, I don't think anyone has come up with a widely accepted method of doing this yet, but it probably can be done.
Already solved in the 1970s. In the MSRE, UF4 powder was placed in a hastelloy-N container with holes in the side, and placed in the salt. The salt dissolved the UF4 out through the holes Ray Van De Walker 04:58, 24 July 2011 (UTC)

Furthermore, I put this paragraph in here because I think there should be some mention for why the msr has not ever become used outside of a research setting. Just saying that its because lwr's are so much more economic kinda misses the point, there is some reason lwrs are much more economic. As for the paragraph heading, and how it is actually written, well nothings perfect, in fact, I know my writings pretty bad. If you think you can do a better job, go ahead, this is wikipedia after all, you don't need anyones permision to change things. That being said, I do not want this article mearly to turn into an advertisement for msr's, this is not a "perfect" technology, it has issues. Lcolson

...which is the reason why I first discuss it, then change it. An edit war is nothing pretty, you know? We'll see. Anyway, what you write is largely true, but misleading. Especially:

- Free oxygen, free fluorine and moisture surely will corrode the metallic walls. However, the chemical potential of the salt has to be controlled anyway so it is slightly on the reducing side, containing some trivalent uranium. So any free oxygen or fluorine will oxydize the uranium ions, not the metal structure. Moisture will be driven out with the off-gas at working temperatures. All this is pretty much a non-issue.

- Cryolithe. Yes, aluminium is produced by electrolysing alumina with cryolithe. This can be considered a mixture or solution of sodium flouride, aluminium fluoride and aluminum oxide, certainly a molten salt. But the cryolithe is really only a fluxing agent, it is chemically non-agressive and it doesn't extract aluminium or something. You hinted that it does, which is really misleading.

- Heating is not a technological issue. Sure, it adds to the cost, but other than that there's no problem. A power reactor would run quite some time without ever being cooled down, refuelling is done by adding some molten or even solid salt, without shutdown, cooling or heating.

- But tritium is a problem. To slow down tritium formation, the lithium in the salt has to be almost pure Li-7, and even then tritium will form. Tritium in the salt is no problem, it doesn't attack metals. Tritium migrating from the salt is a problem. ORNL says, they were able to chemically trap the tritium in the secondary cooling loop. A problem, yes, but nothing major.

And of course there are the political issues. An MSR doesn't fit into the "razor-blade" business model currently employed, research is still needed, and that is expensive, waste reprocessing is currently illegal (though this is stupid when also applied to pyroprocessing), and uranium is too cheap these days to make a breeder economically viable.

(Yes, if we can find some agreement, I'll summarize this and move it to the article proper.)


-- You make several good points, perhaps the essence of the paragraph should be moved under a different heading. Perhaps under advantages-disadvantages, then bulleted and explained. Inaddition to the other advantages and disadvantages of course.

I was just thinknig... It seems like you know quite a bit about this concept, its history, and the issues involved, so you could probably give this article a much more thorough treatment then I've given it. I wrote the majority of this article from what little I learned about the concept researching something else. Therefore its got several holes in it, its definetly not going to become featured status in its current form. Before I expanded it it was a pretty sorry stub, I think it said:

Molten salt reactors are reactors that use molten salts... or something similiar

I would have no problems if you wanted to completely rewrite this article to make it more technically correct. I think I've already done it twice. There are several concepts and parts of its history which I'm sure are probably incorrect. I've tried not to include stuff that I wasn't positive about, but sometimes sources are contradictory. Lcolson

Political Issues[edit]

I thought the law against reprocessing was repealed under Reagan.

And I thought the point of the Molten Salt Reactor reprocessing was to only filter out the fission fragments, and leave the actinides circulating in the fuel. I don't see how there is any risk of a plutonium economy there.

Maybe "only filtering out the fission fragments" came about with the Generation IV initiative, though. I don't know the early history of the reactor concept very well. Oralloy 08:06, 20 December 2005 (UTC)

President Reagan lifted the ban on reprocessing on October 8, 1981:
"(3) I am lifting the indefinite ban which previous adminstrations placed on commercial reprocessing activities in the United States. In addition, we will pursue consistent, long-term policies concerning reprocessing of spent fuel from nuclear power reactors and eliminate regulatory impediments to commerical interest in this technology, while ensuring adequate safeguards."
"It is important that the private sector take the lead in developing commercial reprocessing services. Thus, I am also requesting the Director of the Office of Science and Technology Policy, working with the Secretary of Energy, to undertake a study of the feasibility of obtaining economical plutonium supplies for the Department of Energy by means of a competitive procurement. By encouraging private firms to supply fuel for the breeder program at a cost that does not exceed that of government-produced plutonium, we may be able to provide a stable market for private sector reprocessing and simultaneously reduce the funding needs of the U.S. breeder demonstration program." Oralloy 09:30, 21 December 2005 (UTC)

The ban on reprocessing is lifted, however investors in the commercial reprocessing plants lost billions of dollars when the ban was originally created. I believe they see the cost/benefit to be too low to for something they consider to be very volatile in the market place. The incentive for the utilities to reprocess, at this time, is low because there is a glut of uranium and because the spent fuel created by powerplants is by law, the government's problem, not the utility's. There also may be some policy issues with reprocessing, but I'm not sure about that. Ajnosek 21:18, 5 January 2006 (UTC)

MSR reprocessing is backwards, compared to PUREX. The fission products are removed from the salt, all actinides remain in there. There is of course absolutely no way to extract pure plutonium, let alone weapons grade; the same goes for U-233. No try and explain that to a self proclaimed "nuclear critic". He'll still tell you that reprocessing will be used to construct weapons. Political resistance isn't based on logic, unfortunately.

Section refactor needed[edit]

Some good comments above. Lots of WP:SIGN:unsigned posts but enough meat to refactor the section... which is badly needed IMO! Present section contains much weasel-talk and speculation, mixed with some good information. Andrewa 17:50, 15 May 2007 (UTC)

incorrect statement: Re effects on the biome[edit]

Statement in section Technological Benefits:

"The reactor, like all nuclear plants, has little effect on biomes. In particular, it uses only small amounts of land, relatively small amounts of construction, and the waste is separated from the biome, unlike both fossil and renewable energy projects."

Both operating PWR (Pressurized Water Reactors) in California have been shown to have some negative effects on the ocean area they use as a heat-sink. All nuclear reactors have waste heat that must be disposed of somehow. The siting, for instance, of Diablo Canyon PP in California is 7 miles from the nearest public road. A huge area is off limits and unused around the plant except for a small cattle grazing operation.

I'd argue with this. The diluted waste heat from the reactor has measurable effects, which mimic seasonal changes to which biomes are already adapted. Also, the heat disperses rapidly. On the other hand the alternative is a coal or natural gas plant. The ash, fly-ash and mercury from a coal plant is very large, thousands of tons per GW-year, and the heat rejection is the same. the natural gas plant also has the heat rejection issues, and emits sulfur dioxide and radon. A wind-farm damages multiple square miles with roads and bird hazards. The big solar-thermal plants not only also have the heat rejection, they also turn large parts of deserts into lifeless wastes to cut down on dust. Nuclear effects are very small by comparison with all these. Ray Van De Walker 05:37, 24 July 2011 (UTC)

Also no mention is made of the fire danger of operating graphite at very high temperatures. This, as much as a runaway reaction, caused the problems at Chernobyl. I am not anti-nuke, but think the thorns should be presented along with the rose. —Preceding unsigned comment added by (talk) 23:42, 26 February 2009 (UTC)

Ray Van De Walker 05:37, 24 July 2011 (UTC) Graphite is not a fire hazard in the LFTRs because fires require oxygen. The graphit is literally smothered by inert molten salt under inert helium gas. If the salt is drained, the reactor cell is still filled with inert gas, displaced from the drain tank. If these wonderful safety features are overcome, the graphite is still in an unpressurized reactor (i.e. no explosion hazard), and inside four layers of containment (reactor vessel, hot cell, reactor containment, reactor building). It should rapidly use up the oxygen and go out. Also, the Windscale fire was started by pent-up Wigner energy released in one go by an attempt to anneal Windscale's graphite. Wigner energy can't build up in an MSR's graphite moderator, because it operates at 650C, well above graphite's Wigner annealing temperature of 250C. Ray Van De Walker 05:37, 24 July 2011 (UTC)
    • If you can cite references feel free to put in info, this is wikipedia afterall. Also, if you feel something is not NPOV, as I am sure there several examples, feel free to make it NPOV. It is not good though to combat POV with more POV. That being said, I think most of those concerns are red herrings. I think that they would fit under Nuclear power or Nuclear power debate better than in this article which appears to be more technically oriented anyway. The fact that land has been put land off limits for human use near a nuclear power plant does not mean that nothing is living there or that it has no benefit to the biom. The land around the nuclear power plants is likely some of the most unspoiled natural land around precisely because humans are not allowed on it in large numbers. And the waste heat generation from a high temperature reactor must be compared to that of a conventional power plant. The fact that it can operate on a power cycle that is more efficient than normal (brayton versus rankine) means that it would be generating more electricity per quantity of waste heat. Also, for the most part, the graphite is covered in molten salts, so there would not be contact with oxygen, so there would be no "run away" oxidation. And Chernobyl was a generation 1 reactor designed by the USSR to generate weapons grade plutonium as cheaply as possible; without the numerous safety mechanisms inherent in most generation 2 designs, let alone generation-4 designs such as this, so the comparison is pretty weak in my opinion.Lcolson (talk) 15:10, 27 February 2009 (UTC)
Yes, all thermal power plants need a heat sink.
As far as I know, Diablo Canyon wasn't used for much else before the power plant was built, either.
Graphite is carbon, but large chunks aren't particularly flammable. To get it going, you'd need graphite plus high temperature plus steam, to exploit the water gas shift reaction. Chernobyl had the steam, but a MSR wouldn't.
—WWoods (talk) 18:21, 27 February 2009 (UTC)
Put more simply, the heat sink it does require is about 1/2 that of a standard Rankine cycle turbine. This means air cooled condensers could be used.
I've put a cite needed for the statement that renewable energy emits waste into the biome: I cannot think of a single example of this!? Perhaps solar thermal power station waste heat but that would be the _only example_ but i dont think many of those have been built and as for solar PV, wind, hydro, and wave: not a chance! If I come back and this statement is still there and unsubstantiated I will edit it. It is confusing because it needs to be split into two sentences. Also this new reactor like all reactors (and solar thermal) will still emit some waste heat into the environment so there is quite a bit of manipulative puff in this sentence that I come back and edit and clarify. Actually solar thermal shouldnt generate mush waste heat either like reacors as the mutual idea is to capture and use most of it for power generation unlike fossil plants which will emit alot or waste heat through smoke stacks as CO2. :-) (talk) 03:17, 22 March 2011 (UTC)
Solar cells are electronic heavy metal waste. Roads for windmills introduce foreign plants and animals, including people, horses and cattle, into fragile wildernesses, like mountain ridgetops. Solar thermal and desert PV plants spray sealant on the desert to reduce dust, killing everything. Dams are not truly renewable. They silt up, sometimes in 20 years or less. I myself stepped from the top of a dam in California's San Bernardino Mountains onto the sand and gravel that filled a 160-foot deep "renewable" reservoir that had first drowned a valley. ANd then, there are the deaths from construction. Since renewables have lower energy densities, they have much more, and much more expensive construction, which naturally causes more construction accidents. By comparison, waste heat is rapidly dispersed, and animals and plants (take a deep breath) -like- it. Make the -least- sacrifices. Ray Van De Walker 05:37, 24 July 2011 (UTC)
I think the point should be deleted entirely. It is a claimed advantage of nuclear power, but not specific to the molten salt reactor. This article should compare the MSR to other forms of nuclear power generation and not stray so far afield. NPguy (talk) 01:11, 23 March 2011 (UTC)

No Original Research[edit]

This article contains many arguments based on undocumented assertions, which make it read like a propaganda piece. The views stated may be reasonable, but they need to be attributed. I think this article needs the NPOV tag. NPguy (talk) 03:05, 15 May 2010 (UTC)

Please go read WASH 1097, a U.S. AEC research summary cited at the end of the article, with a web address. Ray Van De Walker 05:40, 24 July 2011 (UTC)

Puff piece[edit]

Golly, after reading this article, I'm like totally convinced. Liquid salt is totally the way to go. It makes me wonder how LWRs could ever compete with them! They have no real drawbacks whatsever!

Maybe a discussion of why we don't use LSMs for power generation could help this article. Rwflammang (talk) 14:49, 19 January 2011 (UTC)

I'm inclined to agree here. There are five sections touting different 'advantages', and only one for 'disadvantages' (which, ironically, carries the NPOV flag) and one for 'challenges'. Much of the article reads like a press release from an industry PR rep, and phrases like "they are an excellent choice to power vehicles, including ships, aircraft and spacecraft" sound like they were pulled from a sales brochure. The Rev (talk) 12:46, 14 March 2011 (UTC)
You guys might as well drop by the page for electric cars and complain they don't compare them to anything but internal combustion cars. Of course the comparisons are all made against light water reactors - nearly every reactor in operation is a LWR, so that's what people know, so that's what they're compared with. If you can find more disadvantages, you should add them instead of complaining about how nobody else did. If it helps, I'm pretty sure I remember seeing something in the news years ago about workers being badly burned in accidents at the Fuji MSR. —Preceding unsigned comment added by (talk) 02:34, 15 March 2011 (UTC)
The problem is not that the comparisons are only with LWRs, but with the tone of the article. It reads like an industry PR and sales brochure. Furthermore, a proper rewrite really should be done by someone with experience in the area rather than an interested amateur as myself. Also, please remember to sign your comments with four tildes (~~~~). The Rev (talk) 12:14, 15 March 2011 (UTC)
What The Rev said. Plus, the problem is that the article gives no explanation of why MSRs have not been able to compete commercially with LWRs world wide. They must have some economic drawbacks which are not mentioned in the article. Rwflammang (talk) 13:36, 15 March 2011 (UTC)
The article does give an explanation. It implies that the reason these reactors don't take off is because the manufacturer can't make money fabricating fuel, which is an asinine argument. The comment likens the nuclear power industry to the inkjet printer market. — Preceding unsigned comment added by Ehidle (talkcontribs) 10:33, 22 July 2011 (UTC)
Not asinine. The nuclear industry is indeed built around the razor and blades business model. There is no profit in constructing new (or even finishing construction on) power plants, but regular annual profit in providing replacement fuel bundles. --IanOsgood (talk) 15:01, 22 July 2011 (UTC)
It must be great to warrant two Technological Advantages sections! —Preceding unsigned comment added by (talk) 17:24, 17 March 2011 (UTC)
I agree about the puffy tone and lack of balance, but it's easy to see why even a markedly superior reactor technology (one with better economy and safety) wouldn't be developed and commercialized in the world as it stands today. What established political or financial interest would gain enough benefit from to overcome barriers of high development cost, long development time, large financial risk, and the enormous inertia of utilities and regulatory bodies? Non-use often good evidence against the inherent merit of a technology, but it's very weak evidence in this instance. (And despite all this, there is, I see, the Fuji Molten Salt Reactor effort.) (talk) 05:11, 21 March 2011 (UTC)
There has to be a reason why its a Generation IV reactor. Maybe it is not fully developed? Maybe a section on that might reduce the puffiness. The CIS (talk) 20:03, 14 June 2011 (UTC)The CIS
I agree that this piece is off the charts in terms of POV. It reads like a sales pitch by a pro-thorium political group. I suggest this gets an NPOV tag. Ehidle (talk) 10:32, 22 July 2011 (UTC)
It's not a puff piece because it describes the disadvantages right out in the open, including the reasons that the reactor is not commercial. Look for the "disadvantges" section (now somewhat corrupted, but still there.) BTW, rhere's no "industry" to puff this thing. The entrenched nuclear industry hates the LFTR as much as the fossil fuel people. I agree that two "advantages sections" is out there. Feel free to combine and edit. (I'll look myself) And you know, guys, sometimes things really are better. Ray Van De Walker 05:47, 24 July 2011 (UTC)

Minor issue with the chart of fission products?[edit]

I was a bit confused with the chart of fission products as there didn't seem to be anything describing the color coding. Should the boxes showing the relative proportions (>7%, >5%, etc.) be color coded instead of all pink?

WRT why they haven't been used in the past, I read once somewhere that the original reason why the AEC was not very interested in LFTRs (one type of LMS that was successfully run at ORNL for several years) was (ironically) because LFTRs did not produce weapons material in useful amounts. This may be bogus, but if it can be confirmed as a factor it would be instructive. Gar37bic (talk) 18:13, 23 January 2011 (UTC)

Regarding Garb37bic statement about reading that the reason that the AEC was not very interested in MSRs because they did not produce weapons materials is a myth that is propagated by uninformed people. It is indeed bogus. The fact is that the AEC made a programmatic decision to focus on liquid metal fast breeder reactors. Gehinjc (talk) 21:37, 7 May 2011 (UTC)

Absolutely true. Also, uranium breeders were prototyped pretty early. The first reactor to generate electricity was an early small prototype breeder reactor built as a proof of concept. Ray Van De Walker 05:52, 24 July 2011 (UTC)

"Technological disadvantages" lists advantages instead - dishonest?[edit]

The section currently titled "Technological disadvantages" doesn't list disadvantages, it lists advantages. This strikes me as a bit dishonest or at least NPOV-ish. I was tempted to rename it "Technological disadvantages that are really advantages because this super duper reactor design doesn't HAVE any disadvantages", which would at least reflect its content. I'm sticking in a NPOV warning instead, less funny but probably more appropriate. -- (talk) 08:09, 13 March 2011 (UTC)

We should go with reasonable conclusions based on what evidence we have, which *is not* the same thing as balance. This bit could be improved though Zeonglow (talk) 00:18, 24 May 2011 (UTC)

I read only one of the bullets that way. The bigger problem is that there are two sections on technological advantages, which should be merged, and two on disadvantages (the second called "challenges" that also should be merged. Other consolidation is also possible. NPguy (talk) 22:08, 13 March 2011 (UTC)

It seems to me that the non-proliferation-related elements are more of trade-offs than advantages or disadvantages, if we want to look at this objectively. On the one hand, the design makes it harder to develop nuclear weapons. On the other hand, the design makes it harder to develop nuclear weapons. ;-)

There is one distinct disadvantage or challenge I see, the generation of HF. That particular bullet seems especially slanted, as the issue is rebutted by saying "it would never happen". It might be more objective to say that this issue is mitigated by the basic design of the reactor, but if circumstances occur beyond the reactor's limits (say, a 9.0 quake) the reactivity of HF needs to be considered during such conditions. Landisdesign (talk) 16:54, 23 March 2011 (UTC)

HF was prevented in the MSRE by using Li7 in the Lithium Fluoride, so neutron transmutation of Li6 to Tritium was mostly prevented. Further, the unmeasurably small amounts that are formed by other processes were swept from the salt by sparging it with small amounts of Helium. (That is, it doesn't happen. No corrosion effects from HF were measured in the MSRE.) A practically-sized power plant might add another piece of equipment to absorb HF from the salt, perhaps with metal reactants. Also, Oak Ridge plans for the full-scale MSR had a second unfueled, nonradioactive salt loop to nonradioactively transfer heat to the steam generators and power turbines. If that salt loop were swept for HF, very little Tritium would escape to anywhere. CANDUs have a comparable problem with Tritium and control it with dessicators in the reactor hall. Ray Van De Walker 06:03, 24 July 2011 (UTC)

Confounding radioactive fuel type with reactor technology[edit]

This article includes some discussions of the relative advantages (and possibly some disadvantages) of thorium fuel. This does not belong. Choice of a fuel is essentially independent of the reactor technology. The article should be scrubbed of information that is not actually about molten salt reactor technology. --Orlady (talk) 19:34, 24 March 2011 (UTC)

There are relevant discussions of various fuels throughout the article. But the big "Thorium cycle advantages" section is unnecessary and a distraction from the main topic.   Will Beback  talk  20:21, 24 March 2011 (UTC)
There is already a wikipedia page on the thorium fuel cycle. This section on thorium fuel cycle should be deleted from this page and a link provided to thorium fuel cycle. Gehinjc (talk) 22:18, 7 May 2011 (UTC)
Perhaps it's not done well in the article, but AFAIK the thorium cycle is relevant. AFAIK, you can chemically separate thorium from uranium with fluorination. This chemical trick does not work with uranium and plutonium because uranium will come out of solution before the plutonium. — Preceding unsigned comment added by (talk) 18:21, 12 July 2011 (UTC)

how can i contribute to this wiki entry by translating it to Chinese?[edit]

as title. —Preceding unsigned comment added by Vapournov (talkcontribs) 14:30, 11 May 2011 (UTC)

If you wish to translate this article into Chinese, go ahead and create a new article at over at Chinese Wikipedia. (Articles in Chinese don't belong here in English Wikipedia, only articles in English, though possibly about Chinese.) Just choose an appropriate title and start editing! Compare e.g. to the Japanese entry here: ja:溶融塩原子炉. — Preceding unsigned comment added by (talk) 05:13, 8 September 2011 (UTC)

Tweeked opening paragraph[edit]

I changed the first paragraph so it scans a little better, sadly the cost of this was a couple of details such as the mention of solid sodium. Hopefully you will agree its best to leave out these details until later in the article Zeonglow (talk) 19:29, 25 May 2011 (UTC)


FTA: "To exploit the molten salt reactor's breeding potential to the fullest, the reactor must be co-located with a reprocessing facility."

I believe this statement to be somewhat misleading; reprocessing refers to a class of processes which separate uranium, other actinides, and fission products from a solid fuel. That is to say, it's "reprocessing" fuel that's already been "processed" into UO2 pellets.

Cleaning the fuel salt is significantly simpler; it's essentially the same fluoridation/reduction process that would be used in the fuel capture process of a LFTR-type MSR, followed by the distillation of the remaining salt mixture. Fission products and Np-237 are removed from an operating reactor without nearly the fuss of reprocessing.

As such, it seems to me that it's inaccurate to characterize fuel salt maintenance as reprocessing. — Preceding unsigned comment added by (talk) 00:15, 3 September 2011 (UTC)

Section reworded to remove POV issues. MegaHasher (talk) 07:04, 13 December 2011 (UTC)
This section "Fissile fuel reprocessing issues," is still confusing and misleading. As mentioned above, footnote 38 at pp. 178-182 discusses the processing of the molten salt fuel to remove fission products, and has nothing to do with reprocessing of solid fuel. As such, the sentence re the 1971 MSBR should be removed because it isn't relevant to fuel reprocessing. Similarly, the next sentence re the DMSR is not accurate because the reference at footnote 39 actually says at p. 99 that "the fuel in a DMSR could be used indefinitely," meaning that reprocessing would never be needed. And, there is nothing about uranium reprocessing; in fact, p. 38 recommends NOT producing excess uranium. The whole section does not make any sense (and should be removed) because no authorities have been cited that discuss any type (or need) of reprocessing of molten salt fuel to recover fissionable uranium or plutonium from spent nuclear fuel (which is how "reprocessing" is defined in the first sentence).Jonathan O. Scott (talk) 21:35, 19 April 2013 (UTC)


I am a layman and have added the following because I am very concerned with energy production particularly in the light of global polluting - which we label climate change. [Could more knowledgeable persons add documentation and references].

It appears difficult to see and compare the thorium reactors to the conventional reactors when in fact there is an amazing differences.

Potentially much lower cost in reactor design : hundreds of millions rather that billions, third world countries are not going to buy a 4 billion dollar reactor when they can not feed their population. 400 million would be more reachable.

Safety: Simpler design, no critical mass as when the electricity turns off so does the reaction - no runaway reaction hence no Chernobyl/Fukushima. These disasters were avoidable through reactor design. Inherent in the standard design is a runaway reaction simply by stacking rods too closely together.

In the order of 100 times less nuclear waste is produced in thorium reactors. The storage/reprocessing of nuclear material has been a highly politically charged issue.

Proven experimental prototype: It has been a spectacular failure that after the experimental reactors were proved their development was abandoned. The only explanation that I believe makes sense is that countries have tied their weapons and civilian energy development together. Even with current market force pressure there has been little development.

Politics: countries need to separate their weapon development and energy development. The science and politics are not meeting, particularly when an idea is already proven something which is a luxury.

Low grade uranium: this term should be on the page. We currently regard low grade uranium as a waste product in other processes. A listing of which countries have the low grade uranium with estimated reserves would be good too. Particularly India which I believe has large deposits, would benefit as their economy will go to polluting coal without alternatives.

As mentioned previously in the discussion there are issues with graphite rods. These should be addressed openly in the reactors design. The potential benefits appear significantly greater than the disadvantages. — Preceding unsigned comment added by (talk) 02:24, 11 December 2011 (UTC)

What you wrote may be true but edits need to be backed up by citations. MegaHasher (talk) 05:13, 13 December 2011 (UTC)

Fused salt purification[edit]

I will try to rewrite this section to address how the salts are purified, using some references from ORNL and Ignatiev. MegaHasher (talk) 09:33, 18 December 2011 (UTC)

cost estimate is outdated[edit]

The reference on the costs of a MSR ( M. W. Moir (2002). Cost of Electricity from Molten Salt Reactors (MSR). 138. Nuclear Technology. pp. 93–95. - currently number 1) gives rather outdated numbers. The article is from 2002, but the numbers are essentially from 1978, only adjusted for inflation. Cost estimates are rather difficult so early in development, and the give difference in price of some 10% is rather small and thus far from significant. Though not much advance in MSR technology happened since 1978 - the regulations have changed. Newer cost estimates for the LWR went up by something like a factor of 2 - and even with this established technology cost estimates are very controversial. So I don't think we can have the claim of low possible costs is possible. The given ref. is at least outdated. --Ulrich67 (talk) 21:06, 12 October 2012 (UTC)

" DOE designation"[edit]

In trying to disambiguate this acronym which occurs under the heading "Molten-salt-cooled reactors", I hesitantly opted for Design of experiments, while guessing that United States Department of Energy might instead have been intended. Help, please! Bjenks (talk) 17:23, 18 March 2013 (UTC)

This has been fixed in the meantime. Of course it means Department Of Energy. I call this  Done --BjKa (talk) 12:12, 15 July 2016 (UTC)

cleanup needed[edit]

The article is a terrible mess. I made an attempt to clean it up, but gave up half way through. Firstly you need to decide whether to treat the project mainly by Timeline, or mainly by Country, or mainly by Technology. And then stick to it. For example the section "Liquid-salt very-high-temperature reactor" seems to concentrate on the technical, but then contains so much reference to U.S. Government funding and recent dates which have really nothing to do with the technical concept. I'm sure this can be untangled somehow, moving blocks around. In my attempt I tried to stick to a basic History section first. But following that there should be a definite outline whether the rest is to be be organized as a listing of the various technical concepts, with geography, politics and timeline mentioned in passing only (and *after* the technical description of the respective concept!), or rather as a political/geographic list, with the various technical concepts clustered under their countries/sponsors.
Also: please try to avoid relative wording like "recent years". An encyclopedic entry should not have to be revised every other year to keep its statements valid.
--BjKa (talk) 11:57, 15 July 2016 (UTC)


I took out the line

  • Alloys based on nickel and iron are prone to embrittlement under high neutron flux.<ref name="Engel-1980"/>{{rp|page=83}}

It would need an explanation what either "high neutron flux" or "nickel and iron" have to do with molten salts. Also why embrittlement under high neutron flux on nickel and iron are no problem in existing LWR power stations. --BjKa (talk) 12:27, 15 July 2016 (UTC)

In conventional LWRs the neutron flux is lower than in the typical proposed molten salt reactors, because a more thermalised spectrum is used in an LWR. The embrittlement might be a problem in LWRs too, but it's easier to take care of. It is one point that can limit the safe lifetime of a reactor vessel and thus the reactor. Essentially all proposals for MSRs assume nickle based alloys for the construction. Having a suitable material to build such a reactor, is a really important requirement.--Ulrich67 (talk) 19:06, 19 July 2016 (UTC)

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