5 ms·

Nice collection of very selective points. To respond to just a few: So if something is complex we shouldn't or can't build it? OK. I hope you aren't an enginee

by binbag 4y ago

Nice collection of very selective points. To respond to just a few: So if something is complex we shouldn't or can't build it? OK. I hope you aren't an engineer. Energy is needed to perform electrolysis to create hydrogen. What about the energy needed to mine uranium? I think it might require quite a lot of effort, particularly once supplies get harder to reach and extract. The parts get radioactive and need maintenance and storage. The radioactivity is much more short term than fission. Fission fuel needs stored away from all life for 100,000 years. It will be a miracle if we manage to achieve that. I think small scale modular fission is a good option, but your arguements against fusion aren't good.

ncmncm 4y ago
The person you are criticizing clearly understands the issues far better than you do. You should read up a bit, instead of just making shit up. https://lvenneri.com/blog/ConFusion https://lvenneri.com/blog/ConFusion
simiones 4y ago
> So if something is complex we shouldn't or can't build it? We were discussing why fusion plants are necessarily more expensive than fission plants - not whether they can (or even should) in principle be built. > Energy is needed to perform electrolysis to create hydrogen. What about the energy needed to mine uranium? I think it might require quite a lot of effort, particularly once supplies get harder to reach and extract. I listed many other energy costs - including some uranium to breed tritium. > The radioactivity is much more short term than fission. Sure, but that still means decades for tritium and centuries for the neutron-bombarded materials - more than enough to make it as big of a problem in our lifetimes per kg, just with many more kg of waste from fusion.
pfdietz 4y ago
He didn't list the worst part (for DT): the volumetric power density of the reactors will suck compared to fission reactors. So not only will the reactors be much more complex than fission reactors, they will also be far larger. How can this possibly be a cheaper source of heat? Fusion's going to have to go with advanced fuels to have a chance. For that and various related reasons, I consider Helion the least dubious of the fusion efforts.
- simiones 4y ago
  Isn't Helion claiming they can achieve non-DT fusion in a few years? That seems extremely suspect to me - as far as I know, non-DT fusion has barely ever been seen in a lab.
  - pfdietz 4y ago
    It's a stretch, but their approach is clever and doesn't seem impossible to me.
    - ncmncm 4y ago
      Apparently even Helion's planned "aneutronic" gadgets produce orders of magnitude more hot neutrons than a fission reactor. All that could make that tolerable is that a 2MW package just produces a lot less of everything than a 2GW (or 20GW) monstrosity.
      - pfdietz 4y ago
        Yes, they do. An important point, though, is that the neutrons from DD fusion are much less energetic than those from DT fusion. This means they (like fission neutrons) are largely below the threshold where (n,alpha) and (n,2n) reactions occur, which eases the radiation damage problem.
        pfdietz 4y ago
        Maybe one order of magnitude more.

by binbag 4y ago

ncmncm 4y ago

The person you are criticizing clearly understands the issues far better than you do. You should read up a bit, instead of just making shit up. https://lvenneri.com/blog/ConFusion https://lvenneri.com/blog/ConFusion

simiones 4y ago

> So if something is complex we shouldn't or can't build it? We were discussing why fusion plants are necessarily more expensive than fission plants - not whether they can (or even should) in principle be built. > Energy is needed to perform electrolysis to create hydrogen. What about the energy needed to mine uranium? I think it might require quite a lot of effort, particularly once supplies get harder to reach and extract. I listed many other energy costs - including some uranium to breed tritium. > The radioactivity is much more short term than fission. Sure, but that still means decades for tritium and centuries for the neutron-bombarded materials - more than enough to make it as big of a problem in our lifetimes per kg, just with many more kg of waste from fusion.

pfdietz 4y ago

He didn't list the worst part (for DT): the volumetric power density of the reactors will suck compared to fission reactors. So not only will the reactors be much more complex than fission reactors, they will also be far larger. How can this possibly be a cheaper source of heat? Fusion's going to have to go with advanced fuels to have a chance. For that and various related reasons, I consider Helion the least dubious of the fusion efforts.

simiones 4y ago
Isn't Helion claiming they can achieve non-DT fusion in a few years? That seems extremely suspect to me - as far as I know, non-DT fusion has barely ever been seen in a lab.
- pfdietz 4y ago
  It's a stretch, but their approach is clever and doesn't seem impossible to me.
  - ncmncm 4y ago
    Apparently even Helion's planned "aneutronic" gadgets produce orders of magnitude more hot neutrons than a fission reactor. All that could make that tolerable is that a 2MW package just produces a lot less of everything than a 2GW (or 20GW) monstrosity.
    - pfdietz 4y ago
      Yes, they do. An important point, though, is that the neutrons from DD fusion are much less energetic than those from DT fusion. This means they (like fission neutrons) are largely below the threshold where (n,alpha) and (n,2n) reactions occur, which eases the radiation damage problem.
      - pfdietz 4y ago
        Maybe one order of magnitude more.