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THE Thorium Thread (merged)

Discussions of conventional and alternative energy production technologies.

THE Thorium Thread (merged)

Unread postby Zero-point » Sat 06 Dec 2008, 20:23:55

link The LFTR is unique, having a hot liquid core thus eliminating fuel fabrication costs and the need for a large reactor. It cannot have a nuclear meltdown and is so safe that typical control rods are not required at all. This design topples all the conventional arguments against conventional energy sources in such areas as:

* Waste Production
* Safety
* Proliferation
* Capital Costs and Location
* Environmental Impact
* Social Acceptance
* Flexibility
* Grid Infrastructure
* Efficiency
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Re: What do you think of Liquid Fluoride Thorium Reactors?

Unread postby mos6507 » Sat 06 Dec 2008, 21:12:25

I'm all for thorium breeder reactors. Not enough talk about it right now.

Here is a good doomer blog site that covers the technology as a mitigator:

Energy From Thorium
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Re: What do you think of Liquid Fluoride Thorium Reactors?

Unread postby Zero-point » Sat 06 Dec 2008, 21:54:25

mos6507 wrote:I'm all for thorium breeder reactors. Not enough talk about it right now.

Here is a good doomer blog site that covers the technology as a mitigator:

Energy From Thorium


Thanks for the link. I remember that blog but didn't check that closely before.
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Re: What do you think of Liquid Fluoride Thorium Reactors?

Unread postby pedalling_faster » Sun 07 Dec 2008, 08:16:18

http://www.columbia.edu/%7Ejeh1/mailing ... _Obama.pdf

James Hansen mentions LFTR's in his advice to Obama.
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Re: What do you think of Liquid Fluoride Thorium Reactors?

Unread postby Tanada » Sun 07 Dec 2008, 13:03:33

Molten Salt Reactors, especially the MOSEL design developed by Germany have a lot of advantages over other types. Two of these are constant waste removal as well as being able to burn any fissionable material as fuel. This design can actually partition waste to the level where it can be harvested for valuable byproducts.
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Re: What do you think of Liquid Fluoride Thorium Reactors?

Unread postby josephmoore » Mon 15 Dec 2008, 01:21:02

I think that the Liquid Fluoride Thorium Reactors are designed in such a way that the partitioned waste can be harvested for the valuable byproducts.
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Re: What do you think of Liquid Fluoride Thorium Reactors?

Unread postby Tanada » Mon 15 Dec 2008, 07:31:49

josephmoore wrote:I think that the Liquid Fluoride Thorium Reactors are designed in such a way that the partitioned waste can be harvested for the valuable byproducts.


They can be, however in all the ubnits built so far they have either not partitioned anything or only partitioned neutron poisons, volitile fission fragments and Protactinium/Uranium.
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Re: What do you think of Liquid Fluoride Thorium Reactors?

Unread postby Dezakin » Tue 16 Dec 2008, 19:47:28

Tanada wrote:
josephmoore wrote:I think that the Liquid Fluoride Thorium Reactors are designed in such a way that the partitioned waste can be harvested for the valuable byproducts.


They can be, however in all the ubnits built so far they have either not partitioned anything or only partitioned neutron poisons, volitile fission fragments and Protactinium/Uranium.

Well, a LFTR would almost certainly partition the Xenon produced because you have to do it to remove the fission products and neutron poisons anyways. It has a high market value on its own and all of the radioisotopes of Xenon have half lives measured in days so you can sell it to industry after a relatively short cooldown period.

The fission platinoids are incredibly valueable, especially the rhodium, but here you have longer half lives with longer cooldown periods, seperation from the carrier salt after vacuum distilation that makes this investment a nice payoff a decade later for specialty idustrial catalysts I imagine. But they would be too radioactive to enter the general public use untill several more decades.

This does however imply that the spent fuel thats been sitting around from the dawn of the nuclear age is ready to be harvested of its platinum group metals however right about now, but the chemistry is all wrong for it to be cheap to extract it from radioactive solid oxide spent fuel rods in zirconium cladding. Its undoubtably cost effective with the much smaller amounts of pure fission products that would be produced from liquid fluoride reactors.
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Re: What do you think of Liquid Fluoride Thorium Reactors?

Unread postby Dezakin » Tue 16 Dec 2008, 20:26:41

I wrote a post speculating on a plausible LFTR for hydrogen production that I took a while to find. Apparently someone saw fit to lump it in a monolithic thread on hydrogen, so I had to do some looking for it.

http://www.peakoil.com/fortopic28695-0-asc-630.html

Liquid fluoride reactors offer two huge advantages over LWRs that are entirely unrelated to their fuel efficiency and their ability to mitigate waste production.

1) They're high temperature. In addition to offering higher thermodynamic efficiency for strait electricity production you can use them for industrial process heat in the 800-1200 C range.

2) They're low pressure. Many friends I have who've done nuclear engineering note that the most troubling aspect of reactor design is the high pressure operation that causes all kinds of headaches from safety concerns to production bottlenecks predicated on single forging reactor vessels.

I'm cautiously optimistic about their deployment. Hopefully the new administration will take a solid look at them.
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THE Thorium Thread (merged)

Unread postby Carlhole » Fri 30 Jul 2010, 16:54:33

tHORIUM rEMIX 2009
Image
Thorium is plentiful and can be turned into energy without generating transuranic wastes. Thorium's potential as fuel was discovered during WW II, but ignored as it was unsuitable for bombs. A liquid-fluoride thorium reactor (LFTR) is the optimal approach for harvesting energy from Thorium, having the potential to solve today's energy/climate crisis. This 10 minute video is summarizes 197 minutes worth of Google Tech Talks on the subject of Thorium & LFTR.

Doomerism is dead. In fact, it never was really alive.
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Re: Thorium Remix 2009

Unread postby EnergyUnlimited » Sat 31 Jul 2010, 01:13:05

Thorium energy is one of very few areas where a genuine progress (as opposite to senseless technoblabbery) is certainly possible.

I have had quite lengthy discussion with one of other members (Dezakin) related to this tech.
He is also an advocate of molten salt thorium reactors but believes that in foreseeable future uranium tech will be superior.

There are still plenty of issues related to molten salt reactor left to resolve and perhaps the most important one is related to removal of lanthanide fission products of high neutron crossection from salt melt.
Failing that our reactor will work for few months at best and remaining mix will become to be just intractable mess.
Need of reprocessing of such mess would easily kill commercial advantages of such project.

Significant chemical development is needed here and much work required particularly in the area of high temperature ion exchangers capable to extract lanthanide and also other fission products out of molten salt mix.
Unfortunately all such materials known up to date are dissolving in said salt mix and are useless by the same.
Salt distillation process might come to a rescue (it is possible to run it at ~1500*C because LiF and BeF2 are volatile at these temperatures and fission products fluorides are not volatile) but halide induced corrosion (pitting) of vessel construction materials and also its thermal stress related deterioration are still not resolved.

So it is still difficult to say anything about prospects of said technology.

For sure there were good reasons for its abandonment in the past.
It may prove successful but it may also fail like commercial FBR did - due to intractable engineering difficulties.
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Re: Liquid Fluoride Thorium Reactors

Unread postby wisconsin_cur » Sun 29 Aug 2010, 18:43:07

http://www.telegraph.co.uk/finance/comment/7970619/Obama-could-kill-fossil-fuels-overnight-with-a-nuclear-dash-for-thorium.html

-Ambrose Evans-Pritchard

Dr Rubbia says a tonne of the silvery metal – named after the Norse god of thunder, who also gave us Thor’s day or Thursday - produces as much energy as 200 tonnes of uranium, or 3,500,000 tonnes of coal. A mere fistful would light London for a week.

Thorium eats its own hazardous waste. It can even scavenge the plutonium left by uranium reactors, acting as an eco-cleaner. "It’s the Big One," said Kirk Sorensen, a former NASA rocket engineer and now chief nuclear technologist at Teledyne Brown Engineering.

"Once you start looking more closely, it blows your mind away. You can run civilisation on thorium for hundreds of thousands of years, and it’s essentially free. You don’t have to deal with uranium cartels," he said.


Among the things I will proclaim in an ideological manner is a disbelief in "magic bullets" but this could be useful and there does not seem to be a more recent thread on the issue.
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Re: Liquid Fluoride Thorium Reactors

Unread postby Tanada » Mon 30 Aug 2010, 15:15:36

wisconsin_cur wrote:http://www.telegraph.co.uk/finance/comment/7970619/Obama-could-kill-fossil-fuels-overnight-with-a-nuclear-dash-for-thorium.html

-Ambrose Evans-Pritchard

Dr Rubbia says a tonne of the silvery metal – named after the Norse god of thunder, who also gave us Thor’s day or Thursday - produces as much energy as 200 tonnes of uranium, or 3,500,000 tonnes of coal. A mere fistful would light London for a week.

Thorium eats its own hazardous waste. It can even scavenge the plutonium left by uranium reactors, acting as an eco-cleaner. "It’s the Big One," said Kirk Sorensen, a former NASA rocket engineer and now chief nuclear technologist at Teledyne Brown Engineering.

"Once you start looking more closely, it blows your mind away. You can run civilisation on thorium for hundreds of thousands of years, and it’s essentially free. You don’t have to deal with uranium cartels," he said.


Among the things I will proclaim in an ideological manner is a disbelief in "magic bullets" but this could be useful and there does not seem to be a more recent thread on the issue.


I'm sorry to have to do it but this is a blatant lie. Thorium 232 or regular Uranium 238 can both be used in a liquid fluoride reactor, the statement that 1 ton is equal to 200 tons is a lie, nothing less. Both can be run in a liquid fluoride reactor and operate it for a very long time because the design is incredibly more efficient than a light water reactor which is the standard system now in use.

I am all for fluoride reactors, always have been since I first learned about them well over a decade ago. Making false claims about them however is not in any way helpful in educating the public and gaining their trust of the science and engineering behind using Fission as a major power supply.
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Re: Liquid Fluoride Thorium Reactors

Unread postby Dezakin » Thu 14 Oct 2010, 20:21:53

Tanada wrote:I'm sorry to have to do it but this is a blatant lie. Thorium 232 or regular Uranium 238 can both be used in a liquid fluoride reactor, the statement that 1 ton is equal to 200 tons is a lie, nothing less.

Its not, but perhaps some context would help next time before such an incendiary response.

A light water reactor requires 200 tonnes of raw uranium to produce 1 GWe in the once through fuel cycle.

A liquid fluoride thorium reactor requires 1 tonne of thorium to produce 1 GWe in the thorium breeder cycle.

Saying that U238 can be used in a liquid fluoroide reactor is true but somewhat misleading and inaccurate. Most fluoride salts have problems with plutonium solubility above a certain point, and so utilizing the uranium plutonium cycle in a fluoride reactor exclusively is impractical. The other problem is the neutron spectrum for plutonium fission favors hard spectra, while fluoride salts often provide too much moderation to effectively burn all the transuranic actinides from a full plutonium cycle. While LFTRs are ideal for thorium cycles, they're suboptimal for uranium cycles.

Now liquid chloride reactors are ideal fast reactor designs, but they're less mature, have issues with require enrichment of chlorine to deplete Cl35 to minimize CL36 production, and would likely face political opposition for proliferation reasons. They are cool however, for having one of the hardest neutron spectra around and having a very high neutron surplus to do whatever alchemy you want with, from actinide incineration, fission product deactivation, or anything else where you need a vast amount of reasonably high energy neutrons.
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Re: Liquid Fluoride Thorium Reactors

Unread postby Tanada » Fri 15 Oct 2010, 05:22:39

Hi Dezakin, nice to see you posting again even though you disagreed with me. Have you ever looked at the early history of the LFR for USAF use? The very early designs were as compact as they could make them and fueled with Uranium. Some variations such as the German design known as MOSEL and its descendants/variants have a much harder neutron spectrum than the classic LFR with its carbon moderator block because they remove all possible moderators other than the salt itself. They averaged out in the epithermal range, just barely high enough to breed Pu-239 sufficient to maintain the reaction in combination with a constant very small input of natural Uranium with its .7% U-235 content. Really remarkable machines, though the Japanese are now working on a Reduced Moderation Water Reactor that they calculate has the same ability, for the same reason though they intend to enrich the solid fuel before the cycle to allow for infrequent refueling as is common industry practice.
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Re: Liquid Fluoride Thorium Reactors

Unread postby Dezakin » Fri 15 Oct 2010, 16:47:20

MOSEL would still have problems actually utilizing a lot of plutonium because of solubility issues. In liquid fluoride reactors we really don't want to be breeding plutonium much. The only purpose of that is to denature the U233 with U238 for proliferation (in other words political nonsense) concerns. My favorite design is the tube in a tube epithermal design. I hate carbon moderators because they become maintenance headaches and also become disposal problems because of neutron activation. I hate D2O because of the huge plumbing problem, even though its just about the best moderator there is. I'd prefer salt only moderation.

Epithermal designs however must necessarily have slightly higher fissile loads. There's still design questions on weather or not to partition neptunium. I prefer not to bother with protactinium partitioning and instead rely on a larger blanket salt volume.

I say proliferation concerns are political nonsense because no one ever breeds weapons material from power reactors. Its too expensive, and using U233 for weapons material is a huge headache because of unfamiliar neutronics for weapons and U232 causing hard gammas that make maintenance and reliability of weapons systems suspect.
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Re: Thorium Remix 2009

Unread postby Dezakin » Sat 16 Oct 2010, 01:06:57

EnergyUnlimited wrote:There are still plenty of issues related to molten salt reactor left to resolve and perhaps the most important one is related to removal of lanthanide fission products of high neutron crossection from salt melt.
Failing that our reactor will work for few months at best and remaining mix will become to be just intractable mess.

That simply isn't true. If that were the case you would have to have refueling times in light water reactors themselves on the order of months rather than ever year or two. The lanthanide fission products aren't significant neutron poisons compared to xenon (which is continuously removed) and certainly can be overcome with higher fissile load and harder neutron spectra. Because of uranium's particularly high affinity to fluorine, fluoridation can remove most of the neutron poisons. Removing these neutron poisons in a design is an obvious goal, but not necessary as you're implying.

Need of reprocessing of such mess would easily kill commercial advantages of such project.

We can't know that now. Reprocessing a fluid fuel matrix online as part of the plant design is a vastly different beast than doing solid oxide PUREX with its host of problems.

Salt distillation process might come to a rescue (it is possible to run it at ~1500*C because LiF and BeF2 are volatile at these temperatures and fission products fluorides are not volatile) but halide induced corrosion (pitting) of vessel construction materials and also its thermal stress related deterioration are still not resolved.

That's news to me. There never was much question as to what to do for the vessels for reprocessing, there's a whole range of materials that would be appropriate for running high temperature molten salts, from graphite to certain types of Hastelloy. That's easy stuff, as aluminum refining deals with these sorts of conditions regularly.

One tricky part is the barrier material in a two fluid core and blanket configuration, such that it doesn't suffer too much damage from neutron erosion while still maintaining enough structural integrity to separate the fluids while being transparent enough to neutrons to allow breeding. We know we can do it for several years, which is good enough to replicate the LWR scenario of changing out fuel rods. The outer vessel doesn't suffer any neutron damage to speak of as the blanket salt absorbs most of it, and so your preference based on neutronics becomes less important.

The other problem that we would like to solve is noble metal plate out on the heat exchangers, and we have some ideas on addressing this issue.

For sure there were good reasons for its abandonment in the past.
It may prove successful but it may also fail like commercial FBR did - due to intractable engineering difficulties.

It was abandoned because of a political battle between Milt Shaw and Alvin Weinberg. The FBR never offered us any solution to any problem we had. It solved a problem of a shortage of plutonium. The LFTR with its low pressure and high temperatures offers a potentially less expensive reactor than the light water reactor, which is why we should pursue it today. There were no showstoppers with the MSBRE. The closest was tellurium induced corrosion of the hastelloy vessel which was resolved by revising the chemistry of the vessel with some titanium.

I'm not unrealistic. If we started doing large scale prototypes (larger than the research reactor at ORNL) we might not have a commercial power reactor for several decades given the timescale of engineering cycles. But if we don't pursue it, it will certainly take longer to develop.

There are a whole host of different designs. Graphite moderated thermal, salt only moderation epithermal, D2O moderation extremely thermal, liquid chloride fast reactors. All different types of geometries, from pan in pan, tube in tube, single fluid, two fluid, a 'one and half' fluid design, all with their different advantages and challenges. Different salt prefrences from FLiBe, FLiNaK, chlorides, etcetera. We have many options.
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Re: Thorium Remix 2009

Unread postby EnergyUnlimited » Sat 16 Oct 2010, 02:57:34

Dezakin wrote:
EnergyUnlimited wrote:There are still plenty of issues related to molten salt reactor left to resolve and perhaps the most important one is related to removal of lanthanide fission products of high neutron crossection from salt melt.
Failing that our reactor will work for few months at best and remaining mix will become to be just intractable mess.

That simply isn't true. If that were the case you would have to have refueling times in light water reactors themselves on the order of months rather than ever year or two. The lanthanide fission products aren't significant neutron poisons compared to xenon (which is continuously removed) and certainly can be overcome with higher fissile load and harder neutron spectra.

Lanthanides (notably Sm149; 74500 barns and Gd 157; 200 000 barns) are still a major trouble. They are an order of magnitude less problematic than Xe 135 is but they are accumulating in the mixture (Sm 149 is not radioactive) and with progress of time they can wipe out enough neutrons to prevent further fission.

Harder neutron spectrum in LFTR may not be achievable.
Fluorine itself has some moderator properties as well (what is often overlooked in on-line discussions).
Perhaps chlorine is better here (in chloride salt melt) but there are other troublesome issues with it.
Because of uranium's particularly high affinity to fluorine, fluoridation can remove most of the neutron poisons. Removing these neutron poisons in a design is an obvious goal, but not necessary as you're implying.

How so?
These poisons will form nonvolatile fluorides.
Nothing will change.
Salt distillation process might come to a rescue (it is possible to run it at ~1500*C because LiF and BeF2 are volatile at these temperatures and fission products fluorides are not volatile) but halide induced corrosion (pitting) of vessel construction materials and also its thermal stress related deterioration are still not resolved.

That's news to me. There never was much question as to what to do for the vessels for reprocessing, there's a whole range of materials that would be appropriate for running high temperature molten salts, from graphite to certain types of Hastelloy. That's easy stuff, as aluminum refining deals with these sorts of conditions regularly.

Hastelloy (variete designed to resist high temperatures) has a an upper range of working temperature at ~1200*C.
http://www.hpalloy.com/alloys/descripti ... LOY_X.html.
Lithium fluoride boils at 1680*C (OK, under vacuum you might chip off 200-300*C) but it will still boil well above maximum working temperature of Hastelloy.

So Hastelloy is still unsuitable for this process.
On another hand AfF3 boils at 1270*C, so under vacuum it may go ~1000*C - well within range of Hastelloy.

Second material mentioned (graphite) is a more or less porous, also quite a brittle one and It may not be suitable (due to safety reasons) for use as construction material for distillation vessels dealing with multi tonnage quantities of highly radioactive stock.
For sure there were good reasons for its abandonment in the past.
It may prove successful but it may also fail like commercial FBR did - due to intractable engineering difficulties.

It was abandoned because of a political battle between Milt Shaw and Alvin Weinberg.

There is a world beyond America.
Weird but true.
I'm not unrealistic. If we started doing large scale prototypes (larger than the research reactor at ORNL) we might not have a commercial power reactor for several decades given the timescale of engineering cycles. But if we don't pursue it, it will certainly take longer to develop.

I don't dismiss this technology.
There is a good chance that working commercial installations can be made.
I am just more cautious than you are.
There are still unresolved technological issues there.
There are a whole host of different designs. Graphite moderated thermal, salt only moderation epithermal, D2O moderation extremely thermal, liquid chloride fast reactors. All different types of geometries, from pan in pan, tube in tube, single fluid, two fluid, a 'one and half' fluid design, all with their different advantages and challenges. Different salt prefrences from FLiBe, FLiNaK, chlorides, etcetera. We have many options.

True.
But up to date we commercialized none.

As per my taste FLiBe is most promissing.
Chloride based designs come next.
Sodium & Potassium based designs are even more difficult to reprocess by salt distillation and less promissing by the same.

Reactor grade chlorine needs isotopic separation (tedious, expensive).
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Re: Thorium Remix 2009

Unread postby Dezakin » Sat 16 Oct 2010, 23:13:08

EnergyUnlimited wrote:
Dezakin wrote:
EnergyUnlimited wrote:There are still plenty of issues related to molten salt reactor left to resolve and perhaps the most important one is related to removal of lanthanide fission products of high neutron crossection from salt melt.
Failing that our reactor will work for few months at best and remaining mix will become to be just intractable mess.

That simply isn't true. If that were the case you would have to have refueling times in light water reactors themselves on the order of months rather than ever year or two. The lanthanide fission products aren't significant neutron poisons compared to xenon (which is continuously removed) and certainly can be overcome with higher fissile load and harder neutron spectra.

Lanthanides (notably Sm149; 74500 barns and Gd 157; 200 000 barns) are still a major trouble. They are an order of magnitude less problematic than Xe 135 is but they are accumulating in the mixture (Sm 149 is not radioactive) and with progress of time they can wipe out enough neutrons to prevent further fission.

They form equilibrium concentration because they form at low concentration. They're at worst annoying.
http://energyfromthorium.com/2010/06/20 ... n-poisons/

Harder neutron spectrum in LFTR may not be achievable.
Fluorine itself has some moderator properties as well (what is often overlooked in on-line discussions).
Perhaps chlorine is better here (in chloride salt melt) but there are other troublesome issues with it.

It certainly isn't overlooked. When we say harder neutron spectrum, we mean epithermal. While Chlorine is fascinating, its far less mature and requires enrichment.

Because of uranium's particularly high affinity to fluorine, fluoridation can remove most of the neutron poisons. Removing these neutron poisons in a design is an obvious goal, but not necessary as you're implying.

How so?
These poisons will form nonvolatile fluorides.
Nothing will change.


You can via brute force remove everything but the uranium using fluoride volatility of UF6 to my knowledge. I humbly bow to those more experienced in molten salt chemistry, but wasn't aware of any real showstopping problems with molten salt reprocessing. Things we'd like to do better sure.

Salt distillation process might come to a rescue (it is possible to run it at ~1500*C because LiF and BeF2 are volatile at these temperatures and fission products fluorides are not volatile) but halide induced corrosion (pitting) of vessel construction materials and also its thermal stress related deterioration are still not resolved.

That's news to me. There never was much question as to what to do for the vessels for reprocessing, there's a whole range of materials that would be appropriate for running high temperature molten salts, from graphite to certain types of Hastelloy. That's easy stuff, as aluminum refining deals with these sorts of conditions regularly.

Hastelloy (variete designed to resist high temperatures) has a an upper range of working temperature at ~1200*C.
http://www.hpalloy.com/alloys/descripti ... LOY_X.html.
Lithium fluoride boils at 1680*C (OK, under vacuum you might chip off 200-300*C) but it will still boil well above maximum working temperature of Hastelloy.

So Hastelloy is still unsuitable for this process.
On another hand AfF3 boils at 1270*C, so under vacuum it may go ~1000*C - well within range of Hastelloy.

Second material mentioned (graphite) is a more or less porous, also quite a brittle one and It may not be suitable (due to safety reasons) for use as construction material for distillation vessels dealing with multi tonnage quantities of highly radioactive stock.[/quote]

I know that the vessel material for vacuum distillation was never a real concern. The problem with the reactor is then you have to find a material that has compatibility with the molten salt along with the appropriate neutronic properties, which is why Hastelloy is desired for barrier materials of two fluid liquid fluoride breeder regimes.

I'll forward your concern to the LFTR community forum relating to vacuum distillation material, as there are several chemists and nuclear engineers there with far more experience than I. I read something about tungsten being an appropriate tubing material

For sure there were good reasons for its abandonment in the past.
It may prove successful but it may also fail like commercial FBR did - due to intractable engineering difficulties.

It was abandoned because of a political battle between Milt Shaw and Alvin Weinberg.

There is a world beyond America.
Weird but true.

There wasn't anyone pursuing liquid halide cooled reactors at this time besides the US, so there was no program to abandon. Much of the blame for abandoning this program lay at the feet of one Milt Shaw.

I'm not unrealistic. If we started doing large scale prototypes (larger than the research reactor at ORNL) we might not have a commercial power reactor for several decades given the timescale of engineering cycles. But if we don't pursue it, it will certainly take longer to develop.

I don't dismiss this technology.
There is a good chance that working commercial installations can be made.
I am just more cautious than you are.
There are still unresolved technological issues there.

Yes, but most of these issues are which engineering compromises we must make. Can we devise a barrier material that lasts the lifetime of the plant or must we replace it every several years. What enrichment are we forced to work with for the start charge? How much plutonium solubility can we allow in a reactor, and must we remove neptunium to prevent solubility issues?

We aren't facing the question on weather we can build a reactor that provides power, we can do that. We don't know how cost effective we can make it yet and I believe we differ on how serious some of the engineering challenges are.

I honestly invite you to ask some of your questions and raise your concerns on Kirk's forum, there are plenty of professionals there who would be better able to answer than me.

There are a whole host of different designs. Graphite moderated thermal, salt only moderation epithermal, D2O moderation extremely thermal, liquid chloride fast reactors. All different types of geometries, from pan in pan, tube in tube, single fluid, two fluid, a 'one and half' fluid design, all with their different advantages and challenges. Different salt prefrences from FLiBe, FLiNaK, chlorides, etcetera. We have many options.

True.
But up to date we commercialized none.

Well, yeah. We haven't even explored on a prototype level more than the single salt graphite moderated FLiBe reactor on a very small scale. I'm pessimistic because developing this technology will require billions of dollars of investment to design and prototype the reactor, the reprocessing system, and to make sure that the concerns (such as the vessel material for vacuum distillation is compatible with the salt) are addressed before scaling up to a full commercial design. I think we will eventually, but the problem is that for decades this has been out of the mindshare. The only breeders anyone really knew about were liquid metal fast breeder reactors.

Sure, this reactor is gaining awareness, but I think its going to take a large government investment to develop it, and that is at least a decade away.

As per my taste FLiBe is most promissing.
Chloride based designs come next.
Sodium & Potassium based designs are even more difficult to reprocess by salt distillation and less promising by the same.

Reactor grade chlorine needs isotopic separation (tedious, expensive).

Yes, really there only are two salt families that have any attention: Fluorides and Chlorides. Fluorides for thermal and epithermal regimes, and chlorides for fast reactor regimes. FLiBe is my preference for thermal reactors as well, for the reasonable moderation ratio, the low neutron absorption and minor neutron multiplication effect of the Beryllium n->2n reaction, and compatibility with many different vessel materials. Thermal regimes are excellent for the thorium fuel cycle.

But chloride reactors are the most awesome. Look, I'm not going to get ahead of myself here because we've not really prototyped any sort of operational chloride salt fast reactor, but the initial estimates give a chloride fuel fast reactor one of the hardest neutron spectra with the highest neutron budget of any reactor design. They can be excellent for incinerating actinides and then doing whatever you want with left over neutrons from deactivating long lived fission products to breeding specialty isotopes. Sure they're a political nightmare because they can breed obscene quantities of Pu239 without much effort, but given they're a good decade or two away after the development of a fluoride reactor regime, they still are fun to think about.

Of course the chlorine enrichment problem makes them a bit expensive, but this is decades away anyways so its still a fun idea to think about. In the meantime, I'd place priority on the liquid fluoride thorium breeder using FLiBe in the two fluid design with online processing of the fuel such that it outcompetes LWRs. Given they have low pressures and high power densities, they've already got some potential cost advantages over LWRs with their requirement for massive pressure vessels.
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Re: Thorium Remix 2009

Unread postby EnergyUnlimited » Sun 17 Oct 2010, 12:36:13

Dezakin wrote:They form equilibrium concentration because they form at low concentration. They're at worst annoying.
http://energyfromthorium.com/2010/06/20 ... n-poisons/

It is big annoyance.
Salt distillation would not be needed, if you don't have to remove neutron poisons other than Xe135.
You can via brute force remove everything but the uranium using fluoride volatility of UF6 to my knowledge. I humbly bow to those more experienced in molten salt chemistry, but wasn't aware of any real showstopping problems with molten salt reprocessing. Things we'd like to do better sure.

I don't understand your argument.
Molten fluoride Thorium reactor converts Th232 into U233 (and a bit of U232).
Thorium doesn't form volatile hexafluoride like Uranium (and with some pain Plutonium) does.
Essentially you would isolate fissile isotope (and you may end up with excursion, if you try it in naive fashion).
However bulk of initial thorium input will still remain mixed with fission products (neutron poisons) and so you will have to dispose this thorium - antithesis of thorium breeder concept.
I'll forward your concern to the LFTR community forum relating to vacuum distillation material, as there are several chemists and nuclear engineers there with far more experience than I. I read something about tungsten being an appropriate tubing material

Would be nice if you let me know, what they think about it.

We have still some considerable problems with fabrication of bulk tungsten items (you will need long sections and significant diameters of tubing).
I don't know how relevant these can be though.

BTW,
Which forum do you have in mind?

There wasn't anyone pursuing liquid halide cooled reactors at this time besides the US, so there was no program to abandon. Much of the blame for abandoning this program lay at the feet of one Milt Shaw.

Indians are meddling with Thorium for quite a while.
It seems sensible to explore molten salts reactors in this context, but they didn't (please correct me if not true).

You may dismiss them, saying that Indians are stupid and don't know what to do, but I don't think it is that simple.
There may be more reasons...

I honestly invite you to ask some of your questions and raise your concerns on Kirk's forum, there are plenty of professionals there who would be better able to answer than me.

This is a good idea.

Sure, this reactor is gaining awareness, but I think its going to take a large government investment to develop it, and that is at least a decade away.

I always wonder why it seems impossible for private corporations to invest these few $ billions?
This is not a lot for many firms.
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