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Genuinely curious - aren't fusion plants both safer and use cheaper-to-get and more-abundant materials?

by eliben 14y ago

ISL 14y ago
See other posts referencing D-T and other fuel cycles. The D is deuterium and the T is tritium. Hydrogen-Hydrogen fusion is more challenging than more exotic types. D-T is, in a sense, the easiest, but both ingredients have non-trivial costs. http://en.wikipedia.org/wiki/Fusion_power#Fuel_cycle http://en.wikipedia.org/wiki/Fusion_power#Fuel_cycle The GP post is erudite on activation. Fusion creates a lot of neutrons, which will render the reactor assembly itself radioactive, especially on short timescales. The waste problem is smaller, especially when compared to non-reprocessed fission waste, but not zero. An upside to fusion is the lack of usable bomb material in the waste stream. So, safer, yes, but not completely safe.
- DennisP 14y ago
  Deuterium is pretty cheap. It's 1/2500 of the hydrogen in seawater and easy to separate. Tritium is bred from lithium, which isn't rare either. The main problem here is that tritium breeding limits the rate at which you can build new reactors. So tritium is going to stay pretty valuable for a while but that price will go down as we build more reactors breeding it. Neutrons are definitely a problem, and that's one advantage of General Fusion's design, which has lots of lead and lithium to capture the neutrons. Of course the whole problem goes away if one of the boron fusion projects works out.
  - ISL 14y ago
    Looks like deuterium is ~$3000/kg, as heavy water is ~$600/kg [1]. Less expensive than I thought, but still far more expensive than hydrogen at <$0.01/kg when purchased from my local public utility. It's unfair to compare with hydrogen though - this study [2] suggests that fusion and wind power are roughly comparable in cost. [1] http://reactorscanada.com/2008/05/21/is-there-enough-heavy-water-for-more-candu-reactors/ http://reactorscanada.com/2008/05/21/is-there-enough-heavy-w... [2] http://www.energyresearch.nl/energieopties/kernfusie/achtergrond/economie/ http://www.energyresearch.nl/energieopties/kernfusie/achterg...
    - DennisP 14y ago
      The best comparison is really to the 12 million kilograms of coal that generates the same amount of energy: http://www.euronuclear.org/info/encyclopedia/f/fusion.htm http://www.euronuclear.org/info/encyclopedia/f/fusion.htm I'm guessing your second link is based on tokamaks, which are generally considered likely to be far more expensive than some of the lesser-known designs. If they project tokamaks to be competitive with wind then I'm pretty encouraged.
bcoates 14y ago
It depends on what kind, as there aren't any viable fusion designs yet. If they involve gigantic magnets or largish amounts of material at surface-of-the-sun temperatures or incredible amounts of neutron flux, costs are going to be high and safety is going to be a problem even compared to fission. If they can miniaturize it like the Lockheed guy in the OP wants then not so much but nobody really knows if that's possible.

Genuinely curious - aren't fusion plants both safer and use cheaper-to-get and more-abundant materials?

by eliben 14y ago

Genuinely curious - aren't fusion plants both safer and use cheaper-to-get and more-abundant materials?

ISL 14y ago

See other posts referencing D-T and other fuel cycles. The D is deuterium and the T is tritium. Hydrogen-Hydrogen fusion is more challenging than more exotic types. D-T is, in a sense, the easiest, but both ingredients have non-trivial costs. http://en.wikipedia.org/wiki/Fusion_power#Fuel_cycle http://en.wikipedia.org/wiki/Fusion_power#Fuel_cycle The GP post is erudite on activation. Fusion creates a lot of neutrons, which will render the reactor assembly itself radioactive, especially on short timescales. The waste problem is smaller, especially when compared to non-reprocessed fission waste, but not zero. An upside to fusion is the lack of usable bomb material in the waste stream. So, safer, yes, but not completely safe.

DennisP 14y ago
Deuterium is pretty cheap. It's 1/2500 of the hydrogen in seawater and easy to separate. Tritium is bred from lithium, which isn't rare either. The main problem here is that tritium breeding limits the rate at which you can build new reactors. So tritium is going to stay pretty valuable for a while but that price will go down as we build more reactors breeding it. Neutrons are definitely a problem, and that's one advantage of General Fusion's design, which has lots of lead and lithium to capture the neutrons. Of course the whole problem goes away if one of the boron fusion projects works out.
- ISL 14y ago
  Looks like deuterium is ~$3000/kg, as heavy water is ~$600/kg [1]. Less expensive than I thought, but still far more expensive than hydrogen at <$0.01/kg when purchased from my local public utility. It's unfair to compare with hydrogen though - this study [2] suggests that fusion and wind power are roughly comparable in cost. [1] http://reactorscanada.com/2008/05/21/is-there-enough-heavy-water-for-more-candu-reactors/ http://reactorscanada.com/2008/05/21/is-there-enough-heavy-w... [2] http://www.energyresearch.nl/energieopties/kernfusie/achtergrond/economie/ http://www.energyresearch.nl/energieopties/kernfusie/achterg...
  - DennisP 14y ago
    The best comparison is really to the 12 million kilograms of coal that generates the same amount of energy: http://www.euronuclear.org/info/encyclopedia/f/fusion.htm http://www.euronuclear.org/info/encyclopedia/f/fusion.htm I'm guessing your second link is based on tokamaks, which are generally considered likely to be far more expensive than some of the lesser-known designs. If they project tokamaks to be competitive with wind then I'm pretty encouraged.

bcoates 14y ago

It depends on what kind, as there aren't any viable fusion designs yet. If they involve gigantic magnets or largish amounts of material at surface-of-the-sun temperatures or incredible amounts of neutron flux, costs are going to be high and safety is going to be a problem even compared to fission. If they can miniaturize it like the Lockheed guy in the OP wants then not so much but nobody really knows if that's possible.