What sort of delayed neutron losses are you talking about when you have the helium sparger occuring before heat exchange and then final return? And does that impact on the stability of the reactor against perturbations? One of the issues with trying to fit so much into a container horizontally is the large opportunities for LOLF, LOCA or just technical difficulty in final assembly from dealing with the profusion of piping. Would it not make better sense to orient the reactor vertically so that a "core catcher" can be designed at the bottom? In this way, the reactor core can sit at the bottom while the calandria holding the D20 surrounds it. Arrangements will have to be made to ensure that calandria break + primary loop break does not result in criticality but you would already have to do this with the horizontal arrangement, anyway. In any case, with the Hx sitting above the core primary loop, Hx breaks would drain, by gravity, back into the primary loop catchment. Same with sparging equipment breaks. Either way, this would probably even allow for a reduction in pumping power because you can arraign the pump such that it either pumps the cold leg down with gravity assist (so that the hot leg also rises with convection assistance) or you can do a counter-current arrangement.
I wouldn't think you'd actually want delayed neutrons causing damage to the heat exchanger. (Or to the offgas system, for that matter.) But why do they consider it worth the trouble to increase fission product removal? To improve burnup?
How do you know the SiC wall won't corrode? Conventional graphite is damaged by neutron flux. How do you prove that the aerographite and SiC will survive for the life of the reactor?
@@CopenhagenAtomics perhaps you mean "by extrapolating"? You probably can't afford to run even a 5-year-long experiment, and I don't know how you would achieve the necessary levels of radioactivity in a lab.
why would you do a thermal spectrum on a waste burner? higher actinides won't go away in a thermal spectrum, and plutonium can breed with a fast spectrum, you can just put used fuel (and the uranium and soluble fission products) into a tin can and run a breeding cycle instead of extracting pure plutonium from the spent fuel (proliferation concern), as well as the strong negative temperature coefficient that comes from having a homogeneous can instead of a graphite moderator swelling with heat/radiation, or heavy water which could boil or even leak into the salt and destroy the structures (try explaining to the people how your oil radiator tube just leaked fission products into their groundwater after being worn away by saltwater corrosion!) you should just do a fast waste burner, it is so much more logical at tackling proliferation concern, fuel cycle (closes the loop instead of always depending on new plutonium for continuing operation of the plant), and the creation of higher actinides (thermal will get you all the way up to americium and curium without fissioning sometimes, fast spectrum is like 99% on pu-239 and 80-90% for each step on the higher actinide chain, as well as 10-20% for u-238)
I don't mean to tear down your design because it is a good idea, but the moderation scheme with the aerographite reminds me of the accelerator driven subcritical systems: it's just like, why are you going through so much trouble when there is a simple solution right in front of you? moderators are optional. if it is running on nuclear waste, there is no reason it oughta be difficult to start with a big fissile inventory, the fuel is literally a liability to its current owners and they will pay you to burn more. the simplest designs are usually the best and most economical, and a big tube of salt that is sized for criticality seems like a million times better solution than "silicon carbide, aerographite, and stainless steel separating heavy water from molten salt with a 500 degree temperature differential so the thing doesn't boil on us" it just seems like you're doing everything in your power to make this more like a fusion reactor, because it's fun to design those, but the world needs good solutions to the problems, not things that have been made high tech for the sake of being high tech. it's a reactor. it takes in waste and makes heat. you can do that without 40 foot radiator tubes making the design location specific because you can't economically drill into bedrock, feel me?
How much bigger is the fuel load in a fast spectrum reactor? I wonder if fitting the whole thing in a shipping container is considered a big advantage.
> higher actinides won't go away in a thermal spectrum This statement is mostly false, especially if you do not have U238 in the salt. I am sure you agree that Pu239 and Pu241 will fission well in thermal spectrum. If you do the simulation over 30 years, then most of the transuranics will fission. (not all) Also see page 25 in this paper for a quick graphical understanding. Even Pu240 will capture a neutron and fission as Pu241 in thermal spectrum. www.osti.gov/etdeweb/servlets/purl/587853 Please also note that there are still some fast neutrons in a thorium molten salt reactor. Also check the table on this page: en.wikipedia.org/wiki/Breeder_reactor
while fast reactors benefits from higher neutron reproduction factors the overall cross sections scales inversely with the neutron energy, translating in to much larger fissile inventories for fast reactors when compared to thermal spectrum reactors. since the power to fissile inventory ratio is one of the primary factors for rapid scaling of a reactor fleet to multi TW level, fast reactors for all their lure will have their lunch eaten by snf kickstarted thermal thorium molten salt reactors.
We've actually come very far with building the technology. As you can see here: ruclips.net/video/MLa2yIzs1_Q/видео.html&ab_channel=CopenhagenAtomics ruclips.net/video/MnxVdjtnvD4/видео.html&ab_channel=CopenhagenAtomics
warning : nuclear scientists in comments ☢️
I don't understand the role of the helium. Could you explain what the helium is doing in this process?
What sort of delayed neutron losses are you talking about when you have the helium sparger occuring before heat exchange and then final return? And does that impact on the stability of the reactor against perturbations?
One of the issues with trying to fit so much into a container horizontally is the large opportunities for LOLF, LOCA or just technical difficulty in final assembly from dealing with the profusion of piping. Would it not make better sense to orient the reactor vertically so that a "core catcher" can be designed at the bottom? In this way, the reactor core can sit at the bottom while the calandria holding the D20 surrounds it. Arrangements will have to be made to ensure that calandria break + primary loop break does not result in criticality but you would already have to do this with the horizontal arrangement, anyway.
In any case, with the Hx sitting above the core primary loop, Hx breaks would drain, by gravity, back into the primary loop catchment. Same with sparging equipment breaks. Either way, this would probably even allow for a reduction in pumping power because you can arraign the pump such that it either pumps the cold leg down with gravity assist (so that the hot leg also rises with convection assistance) or you can do a counter-current arrangement.
I 100% agree
I love molten salt reactors but this one seems very badly designed to me
I wouldn't think you'd actually want delayed neutrons causing damage to the heat exchanger. (Or to the offgas system, for that matter.) But why do they consider it worth the trouble to increase fission product removal? To improve burnup?
@@AlexiLaiho227 the tubes where the fuel are *vertical*. the "plant" is horizontal.
Very interesting presentation, but I wish there was a visible pointer to follow
Thank you for the feedback. That is noted for next time :)
How do you know the SiC wall won't corrode?
Conventional graphite is damaged by neutron flux. How do you prove that the aerographite and SiC will survive for the life of the reactor?
by trying
@@CopenhagenAtomics perhaps you mean "by extrapolating"? You probably can't afford to run even a 5-year-long experiment, and I don't know how you would achieve the necessary levels of radioactivity in a lab.
why would you do a thermal spectrum on a waste burner?
higher actinides won't go away in a thermal spectrum, and plutonium can breed with a fast spectrum, you can just put used fuel (and the uranium and soluble fission products) into a tin can and run a breeding cycle instead of extracting pure plutonium from the spent fuel (proliferation concern), as well as the strong negative temperature coefficient that comes from having a homogeneous can instead of a graphite moderator swelling with heat/radiation, or heavy water which could boil or even leak into the salt and destroy the structures (try explaining to the people how your oil radiator tube just leaked fission products into their groundwater after being worn away by saltwater corrosion!)
you should just do a fast waste burner, it is so much more logical at tackling proliferation concern, fuel cycle (closes the loop instead of always depending on new plutonium for continuing operation of the plant), and the creation of higher actinides (thermal will get you all the way up to americium and curium without fissioning sometimes, fast spectrum is like 99% on pu-239 and 80-90% for each step on the higher actinide chain, as well as 10-20% for u-238)
I don't mean to tear down your design because it is a good idea, but the moderation scheme with the aerographite reminds me of the accelerator driven subcritical systems: it's just like, why are you going through so much trouble when there is a simple solution right in front of you? moderators are optional. if it is running on nuclear waste, there is no reason it oughta be difficult to start with a big fissile inventory, the fuel is literally a liability to its current owners and they will pay you to burn more.
the simplest designs are usually the best and most economical, and a big tube of salt that is sized for criticality seems like a million times better solution than "silicon carbide, aerographite, and stainless steel separating heavy water from molten salt with a 500 degree temperature differential so the thing doesn't boil on us"
it just seems like you're doing everything in your power to make this more like a fusion reactor, because it's fun to design those, but the world needs good solutions to the problems, not things that have been made high tech for the sake of being high tech.
it's a reactor. it takes in waste and makes heat. you can do that without 40 foot radiator tubes making the design location specific because you can't economically drill into bedrock, feel me?
I agree, not only too complicated, but routine reprocessing makes it expensive too. Offsets your molten fuel and efficiency savings.
How much bigger is the fuel load in a fast spectrum reactor? I wonder if fitting the whole thing in a shipping container is considered a big advantage.
> higher actinides won't go away in a thermal spectrum
This statement is mostly false, especially if you do not have U238 in the salt. I am sure you agree that Pu239 and Pu241 will fission well in thermal spectrum. If you do the simulation over 30 years, then most of the transuranics will fission. (not all)
Also see page 25 in this paper for a quick graphical understanding. Even Pu240 will capture a neutron and fission as Pu241 in thermal spectrum.
www.osti.gov/etdeweb/servlets/purl/587853
Please also note that there are still some fast neutrons in a thorium molten salt reactor.
Also check the table on this page:
en.wikipedia.org/wiki/Breeder_reactor
while fast reactors benefits from higher neutron reproduction factors the overall cross sections scales inversely with the neutron energy, translating in to much larger fissile inventories for fast reactors when compared to thermal spectrum reactors. since the power to fissile inventory ratio is one of the primary factors for rapid scaling of a reactor fleet to multi TW level, fast reactors for all their lure will have their lunch eaten by snf kickstarted thermal thorium molten salt reactors.
The concept is just on the drawing board; it is unproven technology and is unlikely to succeed in practice.
That is not even a concept, its a colorful picture, and a guy bubbling about an idea!
We've actually come very far with building the technology. As you can see here:
ruclips.net/video/MLa2yIzs1_Q/видео.html&ab_channel=CopenhagenAtomics
ruclips.net/video/MnxVdjtnvD4/видео.html&ab_channel=CopenhagenAtomics