LFTR is great but more suitable for the long run imo. Short term Check out Ed Pheil of Elysium Industries. His reactor has it all. There is the issue of low cross sections. This can be solved relatively easy by simply using more material.
5:19 This is confusing. After Kirk explains that a fast breeder requires a huge fuel load compared to a thermal-spectrum reactor, and that a fast-spectrum reactor is needed to burn plutonium. Then we have a guy insisting that the plutonium-burning EBR-1 breeder core is 8 inches tall. So which is it? If a fast-spectrum breeder requires a large fuel load, how can this reactor core be so tiny? Another obvious question: if a fast breeder can be both small, and simple enough to become the first power reactor ever made, why did this type of reactor never become popular? Edit: EBR-1 was not first power reactor. Wikipedia: "Electricity had earlier been generated by a nuclear reactor on September 3, 1948 at the X-10 Graphite Reactor in Oak Ridge, Tennessee"
EBR-I ran on almost pure U235 not the plentiful U238. Without moderator, and with almost pure fissile, reactors can be small. Kilopower uses highly enriched U235. I think the trick to a breeder is leveraging the small quantity of fissile into a sustained reaction that can be fed by fertile material. That's the moving-around of fuel rods. Or LFTR's chemical kidney to move U233 (fissile) from blanket salt into the fuel salt. "Huge fuel load" is more "large fissile load". U238 can be fuel, but it isn't considered fissile. U235 is the fissile. Enrichment is the reason to avoid this. The more enrichment is needed, the more expensive the fuel becomes. (And the bigger proliferation concern over the fuel.) For city-powering purposes, consider that CANDU can run on enriched Uranium, thanks to heavy-water moderator. Strangely, heavy-water is one of the technologies excluded from DOE's Advanced Reactor funding program, as of 2020-12. But for niche applications, like submarines and small Oklo power stations, and Kilopower-in-space, enrichment makes sense because no city is being powered. Small size, and long use of fuel loads are priorities.
@@gordonmcdowell If the volume of high-enriched uranium needed fits an 8-inch cube (including fuel assemblies), surely it doesn't cost more than the "over 400 kg" of 19.8% HALEU that would ordinarily be required? (en.wikipedia.org/wiki/Critical_mass ) Indeed, I've heard that the amount of enrichment work needed to go from natural uranium (0.7%) to 20% is more than the amount of enrichment to go from 20% to >90%. Keep in mind that once activated, a breeder can create more fuel than it consumes, so from a cost perspective, a small core ought to make a lot of sense even if the initial fuel load is expensive. I think what this implies is that the reason we don't use small-core breeder reactors has nothing to do with cost or even practicality, and everything to do with the risk of proliferation. Also, it is physically impossible for an ordinary nuclear reactor to explode like a nuclear bomb under any circumstances... but if weapons-grade uranium were used as a fuel, I wonder if it might become possible somehow to detonate it.
How does Flibe's reactor handle the poor delayed neutron fraction of most fissiles relative to U-235? And how does it handle the further reduction of delayed neutron fraction caused by circulation of the fuel into and out of the core, and toward and away from the most active part of the core?
At 0:40, quote: "It's that dip below two. Right there. That's what makes it so you cannot burn up Uranium-238 in a thermal spectrum reactor like a water-cooled reactor." The qualification, "like a water-cooled reactor," needs to be taken out. I know that probably wasn't the intent but it makes it sound like "thermal spectrum" goes with or means "water-cooled" when that just isn't the case. If I understand this, the fact is that no thermal spectrum reactor whether it's water-cooled or molten salt can burn uranium-238.
Gordon, thank you for doing these videos. One question I have is why the water-cooled reactors were ever pursued after the molten salt concept was first demonstrated. Is there some advantage that the water-cooled reactor has that I'm missing? As I understand it, it does not matter what you're burning, whether it's Uranium-233, Uranium-235, or plutonium, or whether it's thermal spectrum or fast spectrum, because with molten salt you don't have to worry about molecular hydrogen being formed or heated liquid water explosively changing into steam, not to mention the economic advantages of increased efficiency.
@@mmandrewa2397 the advantages to LWR were: a) it was there b) it was ready c) it was already paid for by the navy that's really it. that's its main advantages. you could also argue that the fuel form factor (ceramic pellets) helps entrap fission products in a firm cladding for safe disposal, and we have only really ever seen those fail like four times in the history of the world.
@@mmandrewa2397 basically the reason nobody did MSR is because it was mothballed, politically it was swept under the rug, its concept was only "demonstrated" to about 500 people who mostly thought we were going to pursue the LMFBR instead. then when that was mothballed too, we got left with LWR's. it sucks.
How does a higher mass eliment (C) have moderation capabilities, is it a matter of a lot more collisions to slow the neutron down compared to a water moderator (16 to 26 collisions with H or H+ respectively to get in the thermal spectrum)?
Seaborg Technologies are developing a liquid moderator, while just about all thermal-spectrum MSR startups are using graphite. (Transatomic Power was also pursuing non-graphite before they shut down.) If you want a worst-case description of graphite I'd look to Seaborg Tech as they probably have the most pessimistic view of the material. But off-hand I can't quantify the concerns over it... yes it does expand. How serious is that? Dunno. Fission products are created and trapped in the salt (without LFTR chemical kidney) so are build-up of fission products in salt the earlier show-stopper for MSR operation? Graphite has to be the first to go for it to be a problem... so it might be only LFTR would be so worried about graphite because LFTR cleans the fission products out of the salt thus making graphite the show-stopper in terms of reactor lifespan. (Also, ask fast-reactor companies... presumably they'll have a dire perspective on graphite too.)
The graphite moderator is a problem. As far as I have read, the graphite's expansion induces a positive effect on the temperature reactivity coefficient. A negative temperature reactivity coefficient is a significant advantage of using liquid fuels.
Safety first, and failure is not an option, finite engineering, is why this video is the balanced information for energy/human survival in response to the inevitable catastrophe "unforseen". ***** So I just saw how Physicists have made a 5 phase mixture of substances, ie +2 beyond the Triple Point, which means that the Mathematical integration can be applied to all kinds of situations in this e-Pi-i multiphase-locked superposition of states. Putting a more logical spin on the actual Energy Origin, from Observation.
The original Kirk-in-Protospace-Calgary-basement presentation is here: ruclips.net/video/YVSmf_qmkbg/видео.html ...but the topic of thermal-vs-fast was covered by him on many occasions so there might be some info missing from this 2011 delivery that is found in the later remixes.
![Noob To Max With DRAGON REWORK In Blox Fruits [FULL MOVIE]](http://i.ytimg.com/vi/LnBMOinoOvA/mqdefault.jpg)
LFTR is great but more suitable for the long run imo.
Short term Check out Ed Pheil of Elysium Industries.
His reactor has it all.
There is the issue of low cross sections.
This can be solved relatively easy by simply using more material.
Thank you, Kirk, for your tireless promotion of the development of this saner, safer clean nuclear technology.
not clean but yeah sure
5:19 This is confusing. After Kirk explains that a fast breeder requires a huge fuel load compared to a thermal-spectrum reactor, and that a fast-spectrum reactor is needed to burn plutonium. Then we have a guy insisting that the plutonium-burning EBR-1 breeder core is 8 inches tall. So which is it? If a fast-spectrum breeder requires a large fuel load, how can this reactor core be so tiny?
Another obvious question: if a fast breeder can be both small, and simple enough to become the first power reactor ever made, why did this type of reactor never become popular?
Edit: EBR-1 was not first power reactor. Wikipedia: "Electricity had earlier been generated by a nuclear reactor on September 3, 1948 at the X-10 Graphite Reactor in Oak Ridge, Tennessee"
EBR-I ran on almost pure U235 not the plentiful U238. Without moderator, and with almost pure fissile, reactors can be small. Kilopower uses highly enriched U235. I think the trick to a breeder is leveraging the small quantity of fissile into a sustained reaction that can be fed by fertile material. That's the moving-around of fuel rods. Or LFTR's chemical kidney to move U233 (fissile) from blanket salt into the fuel salt.
"Huge fuel load" is more "large fissile load". U238 can be fuel, but it isn't considered fissile. U235 is the fissile.
Enrichment is the reason to avoid this. The more enrichment is needed, the more expensive the fuel becomes. (And the bigger proliferation concern over the fuel.) For city-powering purposes, consider that CANDU can run on enriched Uranium, thanks to heavy-water moderator.
Strangely, heavy-water is one of the technologies excluded from DOE's Advanced Reactor funding program, as of 2020-12.
But for niche applications, like submarines and small Oklo power stations, and Kilopower-in-space, enrichment makes sense because no city is being powered. Small size, and long use of fuel loads are priorities.
@@gordonmcdowell If the volume of high-enriched uranium needed fits an 8-inch cube (including fuel assemblies), surely it doesn't cost more than the "over 400 kg" of 19.8% HALEU that would ordinarily be required? (en.wikipedia.org/wiki/Critical_mass )
Indeed, I've heard that the amount of enrichment work needed to go from natural uranium (0.7%) to 20% is more than the amount of enrichment to go from 20% to >90%.
Keep in mind that once activated, a breeder can create more fuel than it consumes, so from a cost perspective, a small core ought to make a lot of sense even if the initial fuel load is expensive.
I think what this implies is that the reason we don't use small-core breeder reactors has nothing to do with cost or even practicality, and everything to do with the risk of proliferation. Also, it is physically impossible for an ordinary nuclear reactor to explode like a nuclear bomb under any circumstances... but if weapons-grade uranium were used as a fuel, I wonder if it might become possible somehow to detonate it.
How does Flibe's reactor handle the poor delayed neutron fraction of most fissiles relative to U-235? And how does it handle the further reduction of delayed neutron fraction caused by circulation of the fuel into and out of the core, and toward and away from the most active part of the core?
Remember this video when Flibe announces they are using a fast chloride spectrum reactor to breed U233 in the blanket.
At 0:40, quote: "It's that dip below two. Right there. That's what makes it so you cannot burn up Uranium-238 in a thermal spectrum reactor like a water-cooled reactor."
The qualification, "like a water-cooled reactor," needs to be taken out. I know that probably wasn't the intent but it makes it sound like "thermal spectrum" goes with or means "water-cooled" when that just isn't the case. If I understand this, the fact is that no thermal spectrum reactor whether it's water-cooled or molten salt can burn uranium-238.
That's my understanding too. If you specify a timecode m:ss like 0:40 you'll give everyone a hot link.
Gordon, thank you for doing these videos.
One question I have is why the water-cooled reactors were ever pursued after the molten salt concept was first demonstrated. Is there some advantage that the water-cooled reactor has that I'm missing?
As I understand it, it does not matter what you're burning, whether it's Uranium-233, Uranium-235, or plutonium, or whether it's thermal spectrum or fast spectrum, because with molten salt you don't have to worry about molecular hydrogen being formed or heated liquid water explosively changing into steam, not to mention the economic advantages of increased efficiency.
@@mmandrewa2397 the advantages to LWR were:
a) it was there
b) it was ready
c) it was already paid for by the navy
that's really it. that's its main advantages.
you could also argue that the fuel form factor (ceramic pellets) helps entrap fission products in a firm cladding for safe disposal, and we have only really ever seen those fail like four times in the history of the world.
@@mmandrewa2397 basically the reason nobody did MSR is because it was mothballed, politically it was swept under the rug, its concept was only "demonstrated" to about 500 people who mostly thought we were going to pursue the LMFBR instead. then when that was mothballed too, we got left with LWR's. it sucks.
I'm looking for this presentation at 1:54
So I will only need a fast breeding reactors and nothing else or is this just a prestep for another reactor?
How does a higher mass eliment (C) have moderation capabilities, is it a matter of a lot more collisions to slow the neutron down compared to a water moderator (16 to 26 collisions with H or H+ respectively to get in the thermal spectrum)?
Yep. The main advantage of graphite over (light) water is the much lower absorption cross section.
I've read articles that the graphite moderator is the problem and expands and contracts leading to cracking. Does anyone know how significant that is?
Seaborg Technologies are developing a liquid moderator, while just about all thermal-spectrum MSR startups are using graphite. (Transatomic Power was also pursuing non-graphite before they shut down.) If you want a worst-case description of graphite I'd look to Seaborg Tech as they probably have the most pessimistic view of the material. But off-hand I can't quantify the concerns over it... yes it does expand. How serious is that? Dunno. Fission products are created and trapped in the salt (without LFTR chemical kidney) so are build-up of fission products in salt the earlier show-stopper for MSR operation? Graphite has to be the first to go for it to be a problem... so it might be only LFTR would be so worried about graphite because LFTR cleans the fission products out of the salt thus making graphite the show-stopper in terms of reactor lifespan. (Also, ask fast-reactor companies... presumably they'll have a dire perspective on graphite too.)
The graphite moderator is a problem. As far as I have read, the graphite's expansion induces a positive effect on the temperature reactivity coefficient. A negative temperature reactivity coefficient is a significant advantage of using liquid fuels.
Safety first, and failure is not an option, finite engineering, is why this video is the balanced information for energy/human survival in response to the inevitable catastrophe "unforseen".
*****
So I just saw how Physicists have made a 5 phase mixture of substances, ie +2 beyond the Triple Point, which means that the Mathematical integration can be applied to all kinds of situations in this e-Pi-i multiphase-locked superposition of states. Putting a more logical spin on the actual Energy Origin, from Observation.
sodium cooled fast reactors are it. nothing else needed.
Sorry Ed Pheil beats you
agree! you can never burn minor actinides without those extra neutrons
Ugh the editing on this is annoying. Thought I was clicking on a whole uncut discussion/lecture.
The original Kirk-in-Protospace-Calgary-basement presentation is here: ruclips.net/video/YVSmf_qmkbg/видео.html ...but the topic of thermal-vs-fast was covered by him on many occasions so there might be some info missing from this 2011 delivery that is found in the later remixes.