Fusion is much with us these days; late and soon. As the fact that intermittents cannot solve the Gordian Knot starts to sink in, billionaires, journalists, and other experts have turned in desperation to the old Holy Grail. The good news is fusion is getting private funding, so at least it will have a shot if it really is economic. Under ITER style funding, even the best technology would die.
One of the things that Helion’s seventh generation reactor Polaris is supposed to determine is if the current design will produce enough helion (He3) or if they will need two reactors, one dedicated to making it and one consuming it.
I have back of the envelope figured fusion would need somewhere between a 100x and 1000x gain (2-3 orders of magnitude) higher than 'breakeven' to be economic. This seems to line up with that. Probably at the high end of that range...
Well, it sounds like this technology is closely in sync with our corresponding political and economic thinking: trying to get something for nothing (net).
Thanks for this simplified summary. I was not aware of just how unbalanced the input/output scenario still was/is.
Somewhere I had picked up the idea that the input source (fuel?) for this was going to come from sea water or some other source of nearly inexhaustible availability? What am I forgetting or missing?
But I also don't have a problem with continuing reasonable exploratory investments to see if we can make this work, as it supposedly has a great future net benefit vs. initial development cost expenditures. Or am I misinformed about that, too? Or someone could have a new breakthrough idea?!
For some reason the image of reserve banking comes to mind: obtaining credit that is 6, or 10, or 30!! (or 60???!!!!!!) times the initial deposited amount of money. Except maybe we are banking on the full faith and credit of the laws of physics to work in our favor? :-)
Yeah the deuterium for the main deuterium - tritium reaction is from seawater. There should be 1000 years of terrestrial lithium to breed tritium from, after which either a different reaction or seawater lithium mining could provide an unlimited supply
Of course seawater uranium mining has the same fuel supply profile so unlimited energy is equally on the table for fission. 1000 years of terrestrial supply is worth exploring though
I became a fusion fan three years ago. For good reasons such as these this results in me now being more of a fission fan
The tokamak reactor should have a core power density very optimistically of 10 MW/m^3. (Current concepts are pretty tapped out at 5) A fission core has 100. While a fission core isn't that expensive, a fusion core is quite expensive, requiring enormous reinforcing to hold the magnetic forces together making the cost per MWh optimistically in the range of expensive offshore wind without big advances
Basically the case for most fusion concepts is that their "could cost" may be 2-3x as much as fission but maybe regulation will persistently cause fission's cost to be 5x its "should cost"
Fusion is still wonderfully cool to follow. Helion with no steam generator needed is the white knight. If their reactor is capable of D-He3 fusion it will also be able to make He3 from D-D fusion. And also an equal amount of tritium. Pretty interesting question mark of what you do with more tritium than the world has ever seen in terms of hoped for regulation advantage even though it does usefully decay into more He3
I'm in no way a fusion expert, nor do I know much about Helion's plans, but one of the really nice things about the D-He3 reaction is it does not produce neutrons. If they do D-D in the same machine, they bring back all the neutron related issues. I'm guessing they are better off with two reactors.
Unless you can harvest He3 from sources in deep space I don't see D-He3 fusion as very practical. Tritium decays to He3 with a ~12.5 year half life, so you have to make a lot of Tritium and then wait a more than a decade to get half of it.
I was a plasma physics student ~ 50 years ago before doing my Ph.D. in Mechanical Engineering - Materials. Most of the radiation damage in fission reactors is confined to the fuel elements, which are eminently replaceable. The same is not true in fusion reactors, where the fast neutrons are going to bombard the first wall, causing enormous damage. The cladding alloys for fission fuel typically maintain their integrity while each atom has typically been displaced ~ 100 times. Mind you, the cladding is not expected to have much structural value, but it is supposed to hold everything together and help keep it sealed up. The first wall in fusion reactors has to be structurally competent and leak free. It will have to be replaced routinely, and I am sure will be classified as medium level radioactive waste. This is also why the graphite moderators in U-TH molten salt reactors have to be replaced every few years - accumulated radiation damage, Graphite is not as resilient to neutrons as steel and zirconium. And this leaves aside the problems of breeding tritium from lithium. With excellent neutron economy, a fusion reactor should be a slight breeder, but if anything goes wrong, it will be an overall burner, relying upon additional tritum production from other sources.
DD fusion will solve the tritium problem, but requires significantly more demanding plasma conditions. I suspect that DD fusion is probably technically feasible. If t he B-H fusion can be made to work, everything changes, as it has low neutron yield and would allow direct conversion to electrical power - and direct drive for spacecraft.
The biggest problem economically for fusion power is that it is far more complex and capital intensive than fission reactors. And the capital demands of fission power already render its economics to be questionable.
smopecakes is right. Fusion is counting on misdirected, out of control regulation keeping fission's did-cost 5 or more times fission's should-cost. That's why the money is flowing in.
I see no reason why the zero-appearance risk people won't impact the fusion efforts significantly. The first wall components are going to be heavily irradiated and activated, and we already know that people will panic over trace Tritium exposure - look at the fuss over the release of Tritium contaminated water from the Fukashima incident.
The NRC has ruled that fusion will be treated like a accelerator or an MRI machine. I think its called Section 30. Commissioners overruled staff recommendations to do this. We will see if this holds, but right now totally different regime.
There was a radioactive material release in the Czech Republic (I think). Big concern, but then the word got out that it was from a medical facility. Big sigh of relief.
I hope it holds. But the first wall is going to be intensely neutron activated and I would not be surprised if people get worried about the radioactivity from it. Frankly, I worry about the radioactivity of the first wall and inner breeding and cooling blanket wall when it comes time to replace the first wall and vacuum containment vessel during routine maintenance. - Just from the worker exposure angle, our general commercial and industrial electronics are not all that rad hard.
I worked for two years on laser fusion at Lawrence Lab (1975-77). That was right at the beginning, when we thought we could just hit a small sphere of LiDT with laser energy. It soon became clear that we could never get a perfectly spherical implosion due to the fundamental non-uniformity of the laser energy (coherent light) on the spherical surface. We then moved to the current structure, a small replica of an H-bomb, with a cavity to convert the laser light to x-rays, and the spherical implosion then driven by the x-rays. At that point, I realized laser fusion would never be a practical solution to our energy problem. When I watched the "breakthrough" announcement last year, I had mixed feelings - proud of the engineering accomplishment, but worried that the public was being misled about a "breakthrough". I haven't paid much attention to fusion for the last 40 years. It looks like nothing fundamental has changed. I will get interested again, if someone can show me even a conceptual design for a practical, economically feasible power plant.
Indirect drive works, but is too energy demanding. I never believed in laser fusion because I didn't see any way to deal with the radiation damage to the optical elements. The University of Rochester switched their direct drive laser work from fusion to materials research - high density, high pressure, .... Good science, but no relation to power production.
One of the things that Helion’s seventh generation reactor Polaris is supposed to determine is if the current design will produce enough helion (He3) or if they will need two reactors, one dedicated to making it and one consuming it.
Yeah - Helion seems very interesting, at least from the Age of Wonders podcast.
I have back of the envelope figured fusion would need somewhere between a 100x and 1000x gain (2-3 orders of magnitude) higher than 'breakeven' to be economic. This seems to line up with that. Probably at the high end of that range...
Well, it sounds like this technology is closely in sync with our corresponding political and economic thinking: trying to get something for nothing (net).
Thanks for this simplified summary. I was not aware of just how unbalanced the input/output scenario still was/is.
Somewhere I had picked up the idea that the input source (fuel?) for this was going to come from sea water or some other source of nearly inexhaustible availability? What am I forgetting or missing?
But I also don't have a problem with continuing reasonable exploratory investments to see if we can make this work, as it supposedly has a great future net benefit vs. initial development cost expenditures. Or am I misinformed about that, too? Or someone could have a new breakthrough idea?!
For some reason the image of reserve banking comes to mind: obtaining credit that is 6, or 10, or 30!! (or 60???!!!!!!) times the initial deposited amount of money. Except maybe we are banking on the full faith and credit of the laws of physics to work in our favor? :-)
Yeah the deuterium for the main deuterium - tritium reaction is from seawater. There should be 1000 years of terrestrial lithium to breed tritium from, after which either a different reaction or seawater lithium mining could provide an unlimited supply
Of course seawater uranium mining has the same fuel supply profile so unlimited energy is equally on the table for fission. 1000 years of terrestrial supply is worth exploring though
I became a fusion fan three years ago. For good reasons such as these this results in me now being more of a fission fan
The tokamak reactor should have a core power density very optimistically of 10 MW/m^3. (Current concepts are pretty tapped out at 5) A fission core has 100. While a fission core isn't that expensive, a fusion core is quite expensive, requiring enormous reinforcing to hold the magnetic forces together making the cost per MWh optimistically in the range of expensive offshore wind without big advances
Basically the case for most fusion concepts is that their "could cost" may be 2-3x as much as fission but maybe regulation will persistently cause fission's cost to be 5x its "should cost"
Fusion is still wonderfully cool to follow. Helion with no steam generator needed is the white knight. If their reactor is capable of D-He3 fusion it will also be able to make He3 from D-D fusion. And also an equal amount of tritium. Pretty interesting question mark of what you do with more tritium than the world has ever seen in terms of hoped for regulation advantage even though it does usefully decay into more He3
Smopes, Andrew,
I'm in no way a fusion expert, nor do I know much about Helion's plans, but one of the really nice things about the D-He3 reaction is it does not produce neutrons. If they do D-D in the same machine, they bring back all the neutron related issues. I'm guessing they are better off with two reactors.
Unless you can harvest He3 from sources in deep space I don't see D-He3 fusion as very practical. Tritium decays to He3 with a ~12.5 year half life, so you have to make a lot of Tritium and then wait a more than a decade to get half of it.
I was a plasma physics student ~ 50 years ago before doing my Ph.D. in Mechanical Engineering - Materials. Most of the radiation damage in fission reactors is confined to the fuel elements, which are eminently replaceable. The same is not true in fusion reactors, where the fast neutrons are going to bombard the first wall, causing enormous damage. The cladding alloys for fission fuel typically maintain their integrity while each atom has typically been displaced ~ 100 times. Mind you, the cladding is not expected to have much structural value, but it is supposed to hold everything together and help keep it sealed up. The first wall in fusion reactors has to be structurally competent and leak free. It will have to be replaced routinely, and I am sure will be classified as medium level radioactive waste. This is also why the graphite moderators in U-TH molten salt reactors have to be replaced every few years - accumulated radiation damage, Graphite is not as resilient to neutrons as steel and zirconium. And this leaves aside the problems of breeding tritium from lithium. With excellent neutron economy, a fusion reactor should be a slight breeder, but if anything goes wrong, it will be an overall burner, relying upon additional tritum production from other sources.
DD fusion will solve the tritium problem, but requires significantly more demanding plasma conditions. I suspect that DD fusion is probably technically feasible. If t he B-H fusion can be made to work, everything changes, as it has low neutron yield and would allow direct conversion to electrical power - and direct drive for spacecraft.
The biggest problem economically for fusion power is that it is far more complex and capital intensive than fission reactors. And the capital demands of fission power already render its economics to be questionable.
John,
To yr last point. Fission is not capital intensive. It is regulation intensive.
In terms of CAPEX only gas and oil should be cheaper than fission.
Fission should-cost less than coal. Pls see for example
https://jackdevanney.substack.com/p/nuclear-power-not-only-should-be
smopecakes is right. Fusion is counting on misdirected, out of control regulation keeping fission's did-cost 5 or more times fission's should-cost. That's why the money is flowing in.
I see no reason why the zero-appearance risk people won't impact the fusion efforts significantly. The first wall components are going to be heavily irradiated and activated, and we already know that people will panic over trace Tritium exposure - look at the fuss over the release of Tritium contaminated water from the Fukashima incident.
The NRC has ruled that fusion will be treated like a accelerator or an MRI machine. I think its called Section 30. Commissioners overruled staff recommendations to do this. We will see if this holds, but right now totally different regime.
There was a radioactive material release in the Czech Republic (I think). Big concern, but then the word got out that it was from a medical facility. Big sigh of relief.
I hope it holds. But the first wall is going to be intensely neutron activated and I would not be surprised if people get worried about the radioactivity from it. Frankly, I worry about the radioactivity of the first wall and inner breeding and cooling blanket wall when it comes time to replace the first wall and vacuum containment vessel during routine maintenance. - Just from the worker exposure angle, our general commercial and industrial electronics are not all that rad hard.
I worked for two years on laser fusion at Lawrence Lab (1975-77). That was right at the beginning, when we thought we could just hit a small sphere of LiDT with laser energy. It soon became clear that we could never get a perfectly spherical implosion due to the fundamental non-uniformity of the laser energy (coherent light) on the spherical surface. We then moved to the current structure, a small replica of an H-bomb, with a cavity to convert the laser light to x-rays, and the spherical implosion then driven by the x-rays. At that point, I realized laser fusion would never be a practical solution to our energy problem. When I watched the "breakthrough" announcement last year, I had mixed feelings - proud of the engineering accomplishment, but worried that the public was being misled about a "breakthrough". I haven't paid much attention to fusion for the last 40 years. It looks like nothing fundamental has changed. I will get interested again, if someone can show me even a conceptual design for a practical, economically feasible power plant.
Indirect drive works, but is too energy demanding. I never believed in laser fusion because I didn't see any way to deal with the radiation damage to the optical elements. The University of Rochester switched their direct drive laser work from fusion to materials research - high density, high pressure, .... Good science, but no relation to power production.