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PostPosted: Aug 18, 2016 11:18 am 
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KitemanSA,

How? Pu-239 is fast spectrum. Breeding U-233 is thermal spectrum. What did I miss?

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PostPosted: Aug 18, 2016 4:15 pm 
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Tim Meyer wrote:
I apologize for the armchair speculation. Kurt Sellner is better at this. (Well, it's not like you're an experienced nuclear engineer, Kurt. But you've been pretty thorough on this forum.)

I thank you for the kind words but I really don't have much to add here. Of course LFTR can be started from spent nuclear fuel, I thought that was the point. What is preventing this from happening now is the regulatory and business case uncertainty. Current regulations in the USA simply do not have a means to license a molten fuel reactor. It may be possible to build a molten fuel reactor but it'd have to be built under the rules of a solid fuel and water cooled rules, but that means an expensive and unnecessary containment dome as well as using steam turbines instead of the more efficient gas turbines.

The business case comes down to the costs of processing spent fuel from a LWR as opposed to using fresh fuel. That fresh fuel could be enriched uranium from wherever current solid fuel reactors get their fuel or perhaps the stockpiled U-233 the federal government owns and has threatened to down blend and bury for years. The business case also relies on the regulations. Building a LFTR under the rules for a water cooled plant would be exceedingly expensive, which destroys the business case of choosing LFTR over solid fuel designs.

India has decided to build thorium solid fuel reactors as a means to transition to LFTR and, as Mr. Sorensen has stated in one of his videos, there are at least a handful of people that regret that decision.

I've proposed in another thread that spent fuel rods from current solid fuel reactors could be processed by putting the entire fuel assembly in a molten FLiBe bath, bubble some fluorine gas through it, and process the resulting molten mix much like how a LFTR reactor might. The responses were that while this might work it would require a much more complex pyroprocessing system than LFTR would and be more expensive than other existing methods. We have the means to process spent fuel into new fuel but this is often more expensive than just digging up more uranium and enriching that.

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PostPosted: Aug 18, 2016 4:54 pm 
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Kurt Sellner wrote:
I thank you for the kind words[, Tim] but . . .
Folks, Kurt, where I come from names matter. My mother taught me to strive for good manners or I would have to answer to my cosmopolitan (officer & gentleman) father. What does any of this matter if we are not first mindful of mutual respect (with a sense of humor)?

Kurt, your points and perspective seem good to me. The more I learn about the scope of the development and deployment of our favorite reactor design, the more it seems that major decisions have to be made at the highest levels. Nuclear material is very serious business.

How much of the speculations would go away if a prototype were running so measurements could and can be made? It's where Dr. Weinberg left off prior to his dismissal from ORNL in 1973. Union Carbide and other companies had federal contracts in the MSBR days. Our U.S. President has the power and the money to direct the Secretary of Energy to build that prototype in concert with a private developer to complete the engineering specs.

Nuclear reprocessing is obviously mostly shut down around the world. Is France still doing it? I am not an experienced worker from a nuclear reprocessing plant. Is there an EFT member here with that experience? I wouldn't want to speculate too much without hard data here and links to credible references.

Here is a relevant post from July 2013:
From: The explosive cost of disposing of nuclear weapons By Walter Pincus July 3, 2013, The Washington Post:
Quote:
Costs can explode like fireworks when it comes to nuclear weapons disposal.

For example, it could cost more money and take longer to get rid of just 37.5 tons of excess, weapons-grade plutonium than it did for the Manhattan Project to produce the atomic bombs that ended World War II.

Four weapons—the Trinity plutonium implosion device tested in the New Mexico desert; the Little Boy uranium bomb dropped on Hiroshima; the Fat Man plutonium bomb that hit Nagasaki, and an unused uranium bomb—were produced within six years in current dollars of some $24.1 billion, according to Stephen I. Schwartz’s book, “Atomic Audit.”

In comparison, it will cost more than $24.2 billion and take until 2036 for the United States to get rid of those 37.5 tons of plutonium, according to a Government Accountability Office estimate. It appears in the Senate Armed Services report on the fiscal 2014 defense authorization bill. . . .

When the National Nuclear Security Administration (NNSA) originated this MOX program in 2002, design and construction were to cost $1 billion.

By 2005, the estimate was $3.5 billion. When project construction began in 2007, it was three years behind schedule with a $4.8 billion price tag.

According to NNSA’s fiscal 2014 budget request, construction will hit $7.78 billion.

The bottom line is that MOX fuel production is expensive. Fluorinating the Pu for disposal in an MSR would be far cheaper. For all the money spent at Savannah River, LFTR development could have been completed.

To avoid transport risks, the reactors could be placed on-site. Breeding U-233 would be a side benefit and create charges to start civilian LFTRs. [Re: Fissile start up in a LFTR]

Los Alamos also has a stockpile of WG Pu.
Board index » General Nuclear Discussion » Reprocessing, Transmutation, Waste Storage has four pages of topics that began accumulating in 2010. Six years. Wow. This whole nuclear idea appears to be in complete suspended animation. What to do with nuclear wastes from weapons or LWRs?

Reading Walter Pincus' 2013 article is sobering. Here it's three years later and Hanford is still a mess:
Quote:
Everyone agrees Hanford is the nation’s most contaminated nuclear site, and it’s the focus of the nation’s largest environmental cleanup.

To handle treatment of the millions of gallons of highly radioactive liquid waste, much of which dates to the 1940s, the Energy Department decided in 2000 to build a Waste Treatment and Immobilization Plant. The cost was estimated at $4.3 billion with a 2011 completion date. A December 2012 GAO audit said the cost has tripled, to $13.4 billion. Completion is not expected until 2019.

Sound familiar? A report by CBS News last month said that about $40 billion has been spent to clean up Hanford so far, and it could cost an additional $115 billion. Multi-billion-dollar cleanups are going on at other former nuclear weapon sites around the country.

Billions! But Transatomic Power comes along with an interesting "waste annihilating MSR" WAMSR concept born of MIT grads. Secretary Moniz was head of the Department of Physics at MIT from 1991 to 1995. Was Dr. Weinberg correct in his MSR concept? Maybe the molten chloride (37Cl) fast reactor is the better WAMSR? Such impenetrable circumstances. I wouldn't want to be Secretary of Energy.

"Obama plan to de-fund Savannah River plutonium conversion plant draws fire" written earlier this year by Steven Mufson February 25, 2016, for The Washington Post, sheds more light. If we have WG plutonium reprocessing for MOX at Savannah River, SC, it encourages such in Asia (South Korea, China, and North Korea has announced its intentions) and Japan; a situation that opens the door for Pu bomb making.

Members here who seem to want to decouple civilian nuclear energy from weapons might not be facing the realities of nuclear materials. If the molten salt reactor changes the game for the better, then where are the high-level MSR proponents on the world stage?

Is the ORNL Cooperative Research and Development Agreement (CRADA) with the Shanghai Institute for Applied Physics available? What's in that document?

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Last edited by Tim Meyer on Aug 26, 2016 11:54 am, edited 1 time in total.

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PostPosted: Aug 19, 2016 11:28 pm 
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Tim Meyer wrote:
KitemanSA,

How? Pu-239 is fast spectrum. Breeding U-233 is thermal spectrum. What did I miss?

You missed that the Pu239 works just find in a thermal spectrm too, you just can't breed U238 into it in a thermal spectrum. But Spent Nuclear Fuel (SNF) already has plenty of Pu239. So, start with as much Pu239 as needed to start breeding Th/U233. As the U233 is bred, it replaces the Pu239 that is consumed. Eventually, the U233 will exceed the sustainment level and start breeding. At that point you can add just enough U238 to keep the reactor at sustainment.

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PostPosted: Aug 20, 2016 11:06 am 
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Thank you, KitemanSA. That makes sense, for what my non-nuclear engineering brain can process. Apologize for my (possibly inappropriate open) curiosity, were you in Navy reactors before you retired?

Isn't there a lot more to it than that? I thought one major LFTR goal was reduction of TRU production. Maybe the startup of the thorium fuel cycle would be in two classes: "dirty" (utilization of WG Pu-239 that contains "other" isotopes and LWR SNF) for U-233 breeding, and then "clean" (so-called pure U-233 spontaneously forms U-232, yes?). Even a "clean" charge begins developing traces of TRUs just at a much lower level.

This all involves what the government and industry call "processing" that is a mind-bending nuclear issue. The Savannah River Site (SRS) MOX plant is being championed by Senator Lindsey Graham (erstwhile presidential contender) but already Secretary Moniz (Union of Concerned Scientists and others) are pushing for "dilute and dispose" (D&D) being half the cost. Isn't SRS the ideal site for the molten salt technologies?

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—James Arthur Baldwin, American novelist, essayist, playwright, poet, and social critic


Last edited by Tim Meyer on Aug 21, 2016 11:33 am, edited 1 time in total.

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PostPosted: Aug 20, 2016 2:09 pm 
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KitemanSA wrote:
You missed that the Pu239 works just find in a thermal spectrm too, you just can't breed U238 into it in a thermal spectrum.
...
At that point you can add just enough U238 to keep the reactor at sustainment.

I don't follow. Did you mistype perhaps and meant something other than U238? Intentionally adding U238 to a LFTR sounds like a bad idea since it has a very poor cross section for breeding or fission in the thermal spectrum. Those U238 nuclei that do happen to capture a neutron will decay in a matter of hours (about 50 hours?) to Pu239, which has a very large cross section. The neutrons needed to breed the U238 to Pu239 will payback since Pu239 has a multiplication factor of 2.9, which is better than what can be had from U233 or U235, which are less than 2.5. So, I imagine there might be some benefit for this but I have my doubts.

If using SNF, LEU, or most any source of uranium or plutonium we have today there will be some U238 that goes with it, it's unavoidable really. U238 in the fuel is expected, and in the case of a denaturing fuel for legal reasons it is required. In any case it is tolerated, even if it is undesirable or suboptimal. Intentionally adding U238 seems only like a good idea if it is incidental to adding the desired fuel, or if legally required to remain compliant with proliferation regulation.

If one is adding U238 to a LFTR, except when incidental to the starter fuel, then does it fit the definition of LFTR any more? A LFTR can, and must, tolerate U238 in the fuel but if one is adding U238 intentionally after U233 breeding has started then this reactor sounds more like a Transatomic WAMSR or Terrestrial DMSR.

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PostPosted: Aug 21, 2016 12:36 pm 
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Kurt Sellner wrote:
Intentionally adding U238 . . . [might be] legally required to remain compliant with proliferation regulation.
The great benefits of U-233 from thorium outweigh illogical proliferation fears: U-233 utilization naturally involves the presence of U-232 with its ruinous hard gamma field that has always disqualified thorium for nefarious purposes from the birth of the nuclear age, and made its use for civilian power production more challenging for remote shielded automation requirements. I have yet to read those discussions.
Kurt Sellner wrote:
If one is adding U238 to a LFTR, except when incidental to the starter fuel, then does it fit the definition of LFTR any more?
I bet the developer's answer would be a resounding "No!" A pure thorium fuel cycle, once ramped up, runs by fission of bred U-233 that is self-sustaining; consequently, the uranium fuel cycle diminishes during the introduction of thorium-burning FE LFTRs, for example.
Kurt Sellner wrote:
A LFTR can and must tolerate U238 in the fuel, but if one is adding U238 intentionally after U233 breeding has started, then this reactor sounds more like a Transatomic WAMSR or Terrestrial DMSR.
Excellent point, Kurt! The goals of Transatomic Power (TAP), Cambridge, MA, with their WAMSR could be engineered for U-233 breeding to supply Flibe Energy, Inc. LFTRs with start charges, for example. Does the Terrestrial Energy (Canada) IMSR (DMSR) share the same goals as the TAP WAMSR? Both are not interested in thorium start charges. The FE LFTR is expressly a thorium machine.

There is a fair amount of precedent with business consortiums on big federal projects. Given the unavoidable interdependency of civilian nuclear with military for national defense (current U.S. civilian nuclear workforce I believe depends on former Navy nuclear and military nuclear service people), our nation's inevitable nuclear future cannot be accomplished without a change in mission for the U.S. DOE that will require a period of general revenue spending by the DOE. Molten salt fluid fueled reactor technologies have unique and specific engineering requirements that must be found to add to 42 U.S.C. and the 10 CFR (NRC rules). This Manhattan Project II effort can be debt-neutral and profit-generating with skill and common purpose.

The new MSR developers are ready to tackle a major federal retool of our nation's energy infrastructures. It would increase integration of CCS (carbon buffer for the inevitable transition away from carbon for energy) and especially direct thermal chemical and physical processes to transform and upgrade materials markets of all kinds. And the niche markets for solar and wind benefit from new nuclear. Energy is fundamental to modern living. Get energy right and all other issues improve.

When the source of energy is nonemitting (carbon-free) and abundant, the angst of global environmental impacts of growing world economies vanishes. Angst because obviously the installed energy technologies almost necessarily must ignore and in some cases declare climate change a hoax but at the least accept as something that is beyond the carbon industries' ability to change.

Abundant emission-free energy allows for a transformation of carbon processing (most material markets). Chemical engineering of all kinds can radically expand with the make-up nuclear power for CCS processes without nagging fears of polar and glacial ice melt, the possible catastrophic effects on vital ocean currents, ocean acidification impacts on marine ecosystems that terrestrial ecosystems depend on, fears of the consequences of an elevated atmospheric carbon load compared to our preindustrial origins.

That all goes away with an introduction of the immensely powerful thorium energy technologies. A source of energy that once running in the main would eventually have the effect of a decreasing atmospheric carbon load.

A major retool is extremely complex. At once, demands on education, management, and more skyrocket. Like The Manhattan Project, the military-industrial complex that continues to expand, and the Apollo Program. Burgeoning materials technologies give a home to idle capital presently estimated to be many trillions in USD. All this waits for a brave soul to green-light thorium.

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PostPosted: Aug 21, 2016 11:42 pm 
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Tim Meyer wrote:
Thank you, KitemanSA. That makes sense, for what my non-nuclear engineering brain can process. Apologize for my (possibly inappropriate open) curiosity, were you in Navy reactors before you retired?
I was hired into Naval Reactors but switched to another field before I got my clearance. Well, make that the Reactors Group at a shipyard! Never met Rickover.

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Last edited by KitemanSA on Aug 21, 2016 11:56 pm, edited 1 time in total.

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PostPosted: Aug 21, 2016 11:50 pm 
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Tim Meyer wrote:
Isn't there a lot more to it than that? I thought one major LFTR goal was reduction of TRU production. Maybe the startup of the thorium fuel cycle would be in two classes: "dirty" (utilization of WG Pu-239 that contains "other" isotopes and LWR SNF) for U-233 breeding, and then "clean" (so-called pure U-233 spontaneously forms U-232, yes?). Even a "clean" charge begins developing traces of TRUs just at a much lower level.

Reduction of TRU production is a feature of 1 and 2 fluid LFTRs. The use of Spent Nuclear Fuel (SNF) uranium to keep a LFTR at sustainment level is a characteristic of 2.2+Fluid LFTRs. That means that as we use thorium to power the world, we can also get rid of all the UNspent fuel in SNF, and indeed, all the DU left over from making the fuel originally.

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PostPosted: Aug 21, 2016 11:54 pm 
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Kurt Sellner wrote:
If one is adding U238 to a LFTR, except when incidental to the starter fuel, then does it fit the definition of LFTR any more? A LFTR can, and must, tolerate U238 in the fuel but if one is adding U238 intentionally after U233 breeding has started then this reactor sounds more like a Transatomic WAMSR or Terrestrial DMSR.

I define a Liquid Fluoride Thorium Reactor (LFTR) asa reactor that operates primarily on the Th/U233 cycle. If it also burns a small amount U in a U/Pu cycle, that does not make it "not" a LFTR. I call it a 2.2+Fluid LFTR.

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PostPosted: Aug 22, 2016 11:54 am 
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KitemanSA wrote:
I was hired into Naval Reactors but switched to another field before I got my clearance. Well, make that the Reactors Group at a shipyard! Never met Rickover.
Thank you, KitemanSA, for offering some of your background.

I ask because like our host, Mr. Kirk, and Lars, Dr. Le Blanc, and other illustrious members here, those experienced in nuclear work help concerned citizens as myself to understand why the U.S. (founding location of the nuclear age) is not moving forward with new nuclear in the fluid phase when a majority of the leaderships acknowledges the risks of fossil-carbon-based economies that implies a necessary transition.

If molten salt reactors truly are the best way to go, from the outside looking in, when so many scientists and engineers are actively and visibly supporting this route and especially the thorium fuel cycle, it's utterly opaque as to how the many highly-trained individuals currently in the U.S. nuclear wheelhouse do not share this view. I reject conspiracy. Incompetence? How? I know incompetence every time I look in a mirror. Is it a failure of our Constitution being unable to deal with nuclear technologies? What if President Eisenhower had cancelled the U2 flight flown by Captain Powers, and then honored Russia's great invitation to visit? President Eisenhower exited with "beware the military industrial complex." So much for that? "Atoms for Peace" is a delusion in a dangerous world?

I heard a statistic on a C-SPAN segment last night that of our 535 representatives in Congress, only 11% have science and engineering training; about 40% lawyers. Also recognized was the old Jeffersonian concern about our electorate not having adequate training in complex knowledge enough to vote wisely. Great.

WGBH (Boston) hosts Frontine and NOVA. Those two have a lot of reach into the mind of our electorate. But they are silent on this situation. How? Why?

There are studies (to be referenced) showing the impacts of energy technologies on world economies. The fluid fueled reactor technologies especially with the introduction of the thorium fuel cycle seem hugely disruptive; but that is an opportunity for a major improvement in the world economies!

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Last edited by Tim Meyer on Aug 22, 2016 12:43 pm, edited 1 time in total.

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PostPosted: Aug 22, 2016 12:30 pm 
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KitemanSA wrote:
Kurt Sellner wrote:
If one is adding U238 to a LFTR, except when incidental to the starter fuel, then does it fit the definition of LFTR any more? A LFTR can, and must, tolerate U238 in the fuel but if one is adding U238 intentionally after U233 breeding has started then this reactor sounds more like a Transatomic WAMSR or Terrestrial DMSR.

I define a Liquid Fluoride Thorium Reactor (LFTR) as a reactor that operates primarily on the Th/U233 cycle. If it also burns a small amount U in a U/Pu cycle, that does not make it "not" a LFTR. I call it a 2.2+Fluid LFTR.
Ah! But are you free to go beyond the original ORNL definitions (Alvin M. Weinberg, Director) as "one fluid" versus "two fluid"? In any case, you have elaborated on why "0.2" and "+" at: Re: Congratulations to David LeBlanc (ORNL) Thank you! (Forgive this all being beyond my pay grade.)

If it is true that reactor developers are choosing to not employ the online salt chemical processing components as Dr. Alvin was investigating in the early 1970s, and rather making sealed units that do not begin getting processed until as much as ten years after the start of these reactors, how is that anything but the same "kick the can down the road" deal-wth-it-later that is the present state of affairs with LWR SNF assembly inventories?

Rickover? Perhaps it's best you never met him, from the testimonies of those who have. (Dr. Weinberg had him over for dinner. Did you read his recollections?) But Admiral "Rick" accomplished a lot, agreed?

This Wikipedia article on Yucca Mountain nuclear waste repository is alarming if true.
Federal funding for DOE's repository program is currently nonexistent; as of January 2016, no federal appropriations have been authorized to support NRC licensing and/or DOE site investigations at Yucca Mountain. It's worth noting, however, to date the U.S. Department of Energy (DOE) has spent at estimated $8 billion studying the site and constructing the exploratory tunnel beneath Yucca Mountain. Moreover, to actually construct and operate a repository at Yucca Mountain, DOE's own estimate suggests the cost could reach $97 billion.
How much money to develop a TAP WAMSR? Eight billion USD? Ninety-seven billion?

If a "waste annihilating molten salt reactor" is not possible, why has TAP's machine received serious venture capital? Secretary Moniz ran the physics department at MIT and TAP's founders are MIT grads. Don't bury it. Burn it. What's wrong with that? If TRUs can be "annihilated" into 300-year-old FPs and DPs (many are nonemitting rare earths and d-block elements useful for strategic materials markets) that will require geologic deposition, at least there's less of the stuff and it's shorter lived.

But $8 billion gets spent on Yucca Mountain? How much at Hanford? Savannah River Site? And the wind and solar subsidies over the last five years have been $39 billion? At what point does someone with a brain in their head have the courage to blow the whistle and cry, "Foul!" Maybe mine here is a major Horton Hears a Who moment? Or perhaps Dr. Weinberg's vision and the current enthusiasm for molten salt reactors is misplaced or otherwise erroneous?

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PostPosted: Aug 22, 2016 8:40 pm 
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KitemanSA wrote:
Kurt Sellner wrote:
If one is adding U238 to a LFTR, except when incidental to the starter fuel, then does it fit the definition of LFTR any more? A LFTR can, and must, tolerate U238 in the fuel but if one is adding U238 intentionally after U233 breeding has started then this reactor sounds more like a Transatomic WAMSR or Terrestrial DMSR.

I define a Liquid Fluoride Thorium Reactor (LFTR) asa reactor that operates primarily on the Th/U233 cycle. If it also burns a small amount U in a U/Pu cycle, that does not make it "not" a LFTR. I call it a 2.2+Fluid LFTR.


With respect I disagree. A liquid fluoride thorium reactor is a reactor that uses thorium as fuel, if you are proposing a reactor that uses a mix of thorium, uranium, and plutonium as fuel then that certainly falls outside of that definition. Certainly what you propose has similarities with LFTR, and in design may actually be identical, but operating this reactor will involve a different set of parameters and, I'm quite certain, government regulation and oversight.

At a minimum it is confusing to call a reactor that is intended to burn both thorium and plutonium a LFTR. You might differentiate your proposal from the rest of the LFTR family by calling it a "2.2+ fluid LFTR" but since there is no mention of plutonium in that name it muddies the water.

While a LFTR can burn plutonium it's use as a fuel in LFTR is really only tolerated as a starter fuel as a compromise. Plutonium is generally more available than U-233, the ideal starter fuel, and so the people at Flibe Energy propose it as an alternative. As you have pointed out earlier PuF is not very soluble in FLiBe, which is why I'm a bit confused on why you'd propose adding it as a fuel to a reactor that uses FLiBe as a carrier. If you propose using something other than FLiBe as a carrier to better accommodate plutonium as a fuel then you've stepped even further away from how Flibe Energy defines their LFTR concept.

I'm not saying I don't like your idea. I believe your proposal has merit and I can see how a business case can be made for it. I just believe that you should think of a name that better describes it's operation and/or what problem it's trying to solve.

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PostPosted: Aug 22, 2016 10:22 pm 
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Isn't this a lot of speculation? Wasn't it that Dr. Weinberg had a lot more testing to do in the early 1970s when his program was being gutted and he was on the verge of being fired?

Seems that the MSBR program would need to be started again to finish the engineering that is too expensive and too regulated for any one private company.

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PostPosted: Aug 23, 2016 12:23 am 
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Kurt Sellner wrote:
With respect I disagree. A liquid fluoride thorium reactor is a reactor that uses thorium as fuel, if you are proposing a reactor that uses a mix of thorium, uranium, and plutonium as fuel then that certainly falls outside of that definition.
Well, since Sorensen invented the term, I guess he should really have the say. But personally I think your definition is foolish. It implies you cannot start up a LFTR since thorium is not fissile so you need EITHER uranium OR plutonium OR both. It also implies that it would stop being a LFTR the instant any Pu239 gets bred.
The 2.2+ Fluid LFTR runs on thorium and uses SNF extract as a secondary fuel / breeding controller.

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