3 ms·

What makes you think this is going to be cheap? There is a lot of high tech going into this, costs for a fusion device would likely eclipse that of an EUV stepp

What makes you think this is going to be cheap? There is a lot of high tech going into this, costs for a fusion device would likely eclipse that of an EUV stepper (if we are talking small scale devices), for plants the size of ITER that's a whole nother level. Fission was supposed to be super cheap too, but construction costs rendered that a fantasy.

zdragnar 3y ago
Construction costs for fission are largely bloated due to safety, activist and political concerns that span the realm of pragmatic and necessary to pure fantasy as well. Aneutronic fusion would (hopefully) bypass a lot of that.
- rcpt 3y ago
  When it becomes clear that fusion can displace coal those safety, activist and political concerns will immediately pop up again
  - DennisP 3y ago
    And any country that chooses to keep using a dirty, unhealthy, more expensive, 250-year-old energy supply over helium-3 fusion will rapidly fall behind.
    - rcpt 3y ago
      Ok but that's a different story. Just look at what's going on with solar https://twitter.com/ArmandDoma/status/1656323112349179907 https://twitter.com/ArmandDoma/status/1656323112349179907 Yes in theory it should be easy to shut these people up with fusion but historically it hasn't been.
- htag 3y ago
  * The safety is massively different than fission because there is no 'run away' reaction. If you turn off the power, fusion will stop. Fission will keep going once started, and can be very dangerous if the cooling system fails. * I do believe the fusion paths Helios is using emit neutrons, which is a big safety concern. Not only is neutron radiation directly deadly to humans, it's also a challenge to maintain containment. Neutrons are not magnetic, so matter must be used as a shield. Most materials that absorb a neutron will itself become radioactive. I'm unsure about the number of neutrons Helios is emitting, or will emit as they scale up.
  - DennisP 3y ago
    Their combined D-D/D-He3 reaction will emit 6% of its energy as neutron radiation, compared to 80% for D-T. Mostly they'll be lower-energy neutrons, and it's only a 50MW reactor. They don't plan to make it bigger, just to make lots of them. They're considering doing the D-D reaction in a separate reactor to produce the He3. The D-He3 reaction is purely aneutronic, and while some D-D will still happen, they can tune it so it doesn't happen much. That would mean very little neutron radiation at the power plants.
    - htag 3y ago
      > The D-He3 reaction is purely aneutronic, and while some D-D will still happen, they can tune it so it doesn't happen much. That would mean very little neutron radiation at the power plants. Yea. I'm just very curious as to what these numbers look like in practice. Neutrons are essentially waste emissions with their plan, but physics and engineering constrains will determine how much they can tune out D-D reactions.
      - schiffern 3y ago
        > very curious as to what these numbers look like in practice At their stated "optimum" temperature of 200 million kelvin[0] or ~17 keV, the selectivity of the two cross-sections (D-H3/D-D) is about 0.7[1]. Let x = the fraction of D (we'll generously assume no T contamination, so the remainder 1-x is He3), plug in the reaction energies[2], and rearrange. Graph is here: https://www.wolframalpha.com/input?i=plot+y+%3D+1.225+x%5E2%2C+y+%3D+%282.425+x%5E2+%2B+18.3+x+%281+-+x%29+.70%29+from+0+to+1 https://www.wolframalpha.com/input?i=plot+y+%3D+1.225+x%5E2%... The top line is total non-neutron power, and the bottom line is neutron power. The horizontal axis is the fraction of D in the mix, and the vertical axis is proportional to power. It might help compare the relative tradeoffs if you zoom in on the rising slope of the power curve, and normalize both curves to 1: https://www.wolframalpha.com/input?i=plot%3A+y%3D1%2F3.9503+%28+2.425+x%5E2+%2B+12.81+x+%281+-+x%29%29%2C+y+%3D+2.6289+x%5E2+from+0+to+0.61675 https://www.wolframalpha.com/input?i=plot%3A+y%3D1%2F3.9503+... [0] https://www.reuters.com/technology/microsoft-buy-power-nuclear-fusion-company-helion-2023-05-10/ https://www.reuters.com/technology/microsoft-buy-power-nucle... [1] https://commons.wikimedia.org/wiki/File:RxDT-DD-DHe3.jpg https://commons.wikimedia.org/wiki/File:RxDT-DD-DHe3.jpg [2] https://en.wikipedia.org/wiki/Nuclear_fusion#Criteria_and_candidates_for_terrestrial_reactions https://en.wikipedia.org/wiki/Nuclear_fusion#Criteria_and_ca...
- DennisP 3y ago
  In fact, even for D-T fusion the NRC recently decided to regulate reactors like accelerators instead of like fission reactors. Also, we never mass-produced fission reactors. Helion wants to build a factory making twenty 50MW reactors per day, shippable by rail.

zdragnar 3y ago

Construction costs for fission are largely bloated due to safety, activist and political concerns that span the realm of pragmatic and necessary to pure fantasy as well. Aneutronic fusion would (hopefully) bypass a lot of that.

rcpt 3y ago
When it becomes clear that fusion can displace coal those safety, activist and political concerns will immediately pop up again
- DennisP 3y ago
  And any country that chooses to keep using a dirty, unhealthy, more expensive, 250-year-old energy supply over helium-3 fusion will rapidly fall behind.
  - rcpt 3y ago
    Ok but that's a different story. Just look at what's going on with solar https://twitter.com/ArmandDoma/status/1656323112349179907 https://twitter.com/ArmandDoma/status/1656323112349179907 Yes in theory it should be easy to shut these people up with fusion but historically it hasn't been.
htag 3y ago
* The safety is massively different than fission because there is no 'run away' reaction. If you turn off the power, fusion will stop. Fission will keep going once started, and can be very dangerous if the cooling system fails. * I do believe the fusion paths Helios is using emit neutrons, which is a big safety concern. Not only is neutron radiation directly deadly to humans, it's also a challenge to maintain containment. Neutrons are not magnetic, so matter must be used as a shield. Most materials that absorb a neutron will itself become radioactive. I'm unsure about the number of neutrons Helios is emitting, or will emit as they scale up.
- DennisP 3y ago
  Their combined D-D/D-He3 reaction will emit 6% of its energy as neutron radiation, compared to 80% for D-T. Mostly they'll be lower-energy neutrons, and it's only a 50MW reactor. They don't plan to make it bigger, just to make lots of them. They're considering doing the D-D reaction in a separate reactor to produce the He3. The D-He3 reaction is purely aneutronic, and while some D-D will still happen, they can tune it so it doesn't happen much. That would mean very little neutron radiation at the power plants.
  - htag 3y ago
    > The D-He3 reaction is purely aneutronic, and while some D-D will still happen, they can tune it so it doesn't happen much. That would mean very little neutron radiation at the power plants. Yea. I'm just very curious as to what these numbers look like in practice. Neutrons are essentially waste emissions with their plan, but physics and engineering constrains will determine how much they can tune out D-D reactions.
    - schiffern 3y ago
      > very curious as to what these numbers look like in practice At their stated "optimum" temperature of 200 million kelvin[0] or ~17 keV, the selectivity of the two cross-sections (D-H3/D-D) is about 0.7[1]. Let x = the fraction of D (we'll generously assume no T contamination, so the remainder 1-x is He3), plug in the reaction energies[2], and rearrange. Graph is here: https://www.wolframalpha.com/input?i=plot+y+%3D+1.225+x%5E2%2C+y+%3D+%282.425+x%5E2+%2B+18.3+x+%281+-+x%29+.70%29+from+0+to+1 https://www.wolframalpha.com/input?i=plot+y+%3D+1.225+x%5E2%... The top line is total non-neutron power, and the bottom line is neutron power. The horizontal axis is the fraction of D in the mix, and the vertical axis is proportional to power. It might help compare the relative tradeoffs if you zoom in on the rising slope of the power curve, and normalize both curves to 1: https://www.wolframalpha.com/input?i=plot%3A+y%3D1%2F3.9503+%28+2.425+x%5E2+%2B+12.81+x+%281+-+x%29%29%2C+y+%3D+2.6289+x%5E2+from+0+to+0.61675 https://www.wolframalpha.com/input?i=plot%3A+y%3D1%2F3.9503+... [0] https://www.reuters.com/technology/microsoft-buy-power-nuclear-fusion-company-helion-2023-05-10/ https://www.reuters.com/technology/microsoft-buy-power-nucle... [1] https://commons.wikimedia.org/wiki/File:RxDT-DD-DHe3.jpg https://commons.wikimedia.org/wiki/File:RxDT-DD-DHe3.jpg [2] https://en.wikipedia.org/wiki/Nuclear_fusion#Criteria_and_candidates_for_terrestrial_reactions https://en.wikipedia.org/wiki/Nuclear_fusion#Criteria_and_ca...
DennisP 3y ago
In fact, even for D-T fusion the NRC recently decided to regulate reactors like accelerators instead of like fission reactors. Also, we never mass-produced fission reactors. Helion wants to build a factory making twenty 50MW reactors per day, shippable by rail.