4 ms·

This is another of many "silver bullet" proposals to reverse the environmental damage caused by Western civilization. Most of they won't work and will have unin

This is another of many "silver bullet" proposals to reverse the environmental damage caused by Western civilization. Most of they won't work and will have unintended consequences. As always, prevention is the best cure.

mises 8y ago
Only by Western civilization? China is the largest polluter; India is third. The West may not be blameless, but it is not solely the fault thereof. What is your better idea, now that the time for prevention has passed?
- mschuster91 8y ago
  Yeah but most nuclear waste came from the US, UK, France and Russia. As for a better idea, molten salt/thorium reactors, they can eat at least the highly dangerous/ultra long half life stuff.
  - acidburnNSA 8y ago
    Fast neutron reactors can. Most thorium MSRs are slow neutron reactors and struggle to transmute significant used nuclear fuel.
    - arcticbull 8y ago
      My understanding is that Thorium reactors are far less likely to produce transuranic elements with long half-lives, and less waste in general (two order of magnitude). [1] However, it does in fact require some fissile material such as recycled plutonium, so the two reactor kinds can work in conjunction to yield a net drop in long-half-life nuclear wastes. [2] [1] https://en.wikipedia.org/wiki/Thorium-based_nuclear_power https://en.wikipedia.org/wiki/Thorium-based_nuclear_power [2] http://www.world-nuclear.org/information-library/current-and-future-generation/thorium.aspx http://www.world-nuclear.org/information-library/current-and...
      - acidburnNSA 8y ago
        Here's the authoritative summary of the capabilities of transmutation and partitioning [1]. Thorium reactors do indeed produce fewer transuranics, since Thorium-232 is 6 AMUs lower down the chain than Uranium-238. Used nuclear fuel is generally 95% U-238, 1% Pu and minor actinides, and 4% fission products. If you do chemical separation to partition the transuranics you can then try to burn them in a variety of reactors. In slow-neutron reactors using Thorium or Uranium fuel, they'll burn ok if they're well partitioned. In fast-neutron reactors, you can burn them with out as aggressive of partitioning. So it's probably easier and cheaper to reprocess UNF for fast reactors. They're far less sensitive to neutron-poisons and fertile species (e.g. fission products and U-238). Any breeder reactor will make 2 orders of magnitude less TOTAL waste than a non-breeder. Thorium can breed with slow neutrons (which requires continuous removal of the neutron poisons via online chemistry, usually requiring fluid fuel). Uranium can breed with fast neutrons in solid fuel or in fluid fuel. Note I say total waste, not high level waste. High-level waste is proportional only to the burnup (fraction of the fuel you put in that gets fissioned) and doesn't include any process waste from before that (e.g. enrichment or reprocessing waste like U-238). In a fast neutron uranium-fueled reactor, you can transmute the hell out of all actinides, leading to waste that decays to low levels in a few hundred years. See the link below. Thorium's only true physical advantage is that it alone allows breeding with slow neutrons, which can be done with low fissile densities. Other than that, Uranium and Thorium have pretty similar characteristics and capabilities in advanced reactors. [1] https://www.iaea.org/publications/7112/implications-of-partitioning-and-transmutation-in-radioactive-waste-management https://www.iaea.org/publications/7112/implications-of-parti...
        arcticbull 8y ago
        Thank you! This is why I come here :)
  - adventured 8y ago
    > Yeah but most nuclear waste came from the US, UK, France and Russia. That's merely a short question of time. China will end up #1 on that list. The US only has 98 nuclear reactors in total. The UK has a mere 15. China already has 45 operating, with more than a dozen under construction. In less than 15 years they'll surpass the US figure. Nuclear power will be used by more nations in the future, rather than fewer. It rather emphasizes the importance to all nations of waste disposal breakthroughs.
6nf 8y ago
This is about nuclear waste that came from power plants that massively helped the amount of greenhouse gases we emit (cause the alternatives were fossil fuelled plants) so I’m not sure what you mean exactly
arcticbull 8y ago
Everything we do is about trade-offs. Solar panels have toxic chemicals, too (Cadmium compounds, Hexaflouroethane, Lead [1]). Wind involves rare-earth metals like Neodymium which are produced in mines that resemble toxic war zones in far-flung regions of China [2]. None of us will ever exist on this earth without leaving fingerprints. It's not about 'zero' it's about 'better' one step at a time. Defeatism and refusing to accept anything short of perfection is a good way to get nowhere. For reference 1 ton of Thorium produces as much electricity as 200 tons of Uranium or 3.5 megatons of coal -- which would you rather use? [1] https://sciencing.com/toxic-chemicals-solar-panels-18393.html https://sciencing.com/toxic-chemicals-solar-panels-18393.htm... [2] https://www.dailymail.co.uk/news/article-1241872/EXCLUSIVE-Inside-Chinas-secret-toxic-unobtainium-mine.html https://www.dailymail.co.uk/news/article-1241872/EXCLUSIVE-I... [3] https://en.wikipedia.org/wiki/Thorium-based_nuclear_power https://en.wikipedia.org/wiki/Thorium-based_nuclear_power
dang 8y ago
Maybe so, but can you please not post unsubstantive comments to HN, especially about grand divisive topics? It leads to much less specific and much less interesting discussion. https://news.ycombinator.com/newsguidelines.html https://news.ycombinator.com/newsguidelines.html

mises 8y ago

Only by Western civilization? China is the largest polluter; India is third. The West may not be blameless, but it is not solely the fault thereof. What is your better idea, now that the time for prevention has passed?

mschuster91 8y ago
Yeah but most nuclear waste came from the US, UK, France and Russia. As for a better idea, molten salt/thorium reactors, they can eat at least the highly dangerous/ultra long half life stuff.
- acidburnNSA 8y ago
  Fast neutron reactors can. Most thorium MSRs are slow neutron reactors and struggle to transmute significant used nuclear fuel.
  - arcticbull 8y ago
    My understanding is that Thorium reactors are far less likely to produce transuranic elements with long half-lives, and less waste in general (two order of magnitude). [1] However, it does in fact require some fissile material such as recycled plutonium, so the two reactor kinds can work in conjunction to yield a net drop in long-half-life nuclear wastes. [2] [1] https://en.wikipedia.org/wiki/Thorium-based_nuclear_power https://en.wikipedia.org/wiki/Thorium-based_nuclear_power [2] http://www.world-nuclear.org/information-library/current-and-future-generation/thorium.aspx http://www.world-nuclear.org/information-library/current-and...
    - acidburnNSA 8y ago
      Here's the authoritative summary of the capabilities of transmutation and partitioning [1]. Thorium reactors do indeed produce fewer transuranics, since Thorium-232 is 6 AMUs lower down the chain than Uranium-238. Used nuclear fuel is generally 95% U-238, 1% Pu and minor actinides, and 4% fission products. If you do chemical separation to partition the transuranics you can then try to burn them in a variety of reactors. In slow-neutron reactors using Thorium or Uranium fuel, they'll burn ok if they're well partitioned. In fast-neutron reactors, you can burn them with out as aggressive of partitioning. So it's probably easier and cheaper to reprocess UNF for fast reactors. They're far less sensitive to neutron-poisons and fertile species (e.g. fission products and U-238). Any breeder reactor will make 2 orders of magnitude less TOTAL waste than a non-breeder. Thorium can breed with slow neutrons (which requires continuous removal of the neutron poisons via online chemistry, usually requiring fluid fuel). Uranium can breed with fast neutrons in solid fuel or in fluid fuel. Note I say total waste, not high level waste. High-level waste is proportional only to the burnup (fraction of the fuel you put in that gets fissioned) and doesn't include any process waste from before that (e.g. enrichment or reprocessing waste like U-238). In a fast neutron uranium-fueled reactor, you can transmute the hell out of all actinides, leading to waste that decays to low levels in a few hundred years. See the link below. Thorium's only true physical advantage is that it alone allows breeding with slow neutrons, which can be done with low fissile densities. Other than that, Uranium and Thorium have pretty similar characteristics and capabilities in advanced reactors. [1] https://www.iaea.org/publications/7112/implications-of-partitioning-and-transmutation-in-radioactive-waste-management https://www.iaea.org/publications/7112/implications-of-parti...
      - arcticbull 8y ago
        Thank you! This is why I come here :)
- adventured 8y ago
  > Yeah but most nuclear waste came from the US, UK, France and Russia. That's merely a short question of time. China will end up #1 on that list. The US only has 98 nuclear reactors in total. The UK has a mere 15. China already has 45 operating, with more than a dozen under construction. In less than 15 years they'll surpass the US figure. Nuclear power will be used by more nations in the future, rather than fewer. It rather emphasizes the importance to all nations of waste disposal breakthroughs.

6nf 8y ago

This is about nuclear waste that came from power plants that massively helped the amount of greenhouse gases we emit (cause the alternatives were fossil fuelled plants) so I’m not sure what you mean exactly

arcticbull 8y ago

Everything we do is about trade-offs. Solar panels have toxic chemicals, too (Cadmium compounds, Hexaflouroethane, Lead [1]). Wind involves rare-earth metals like Neodymium which are produced in mines that resemble toxic war zones in far-flung regions of China [2]. None of us will ever exist on this earth without leaving fingerprints. It's not about 'zero' it's about 'better' one step at a time. Defeatism and refusing to accept anything short of perfection is a good way to get nowhere. For reference 1 ton of Thorium produces as much electricity as 200 tons of Uranium or 3.5 megatons of coal -- which would you rather use? [1] https://sciencing.com/toxic-chemicals-solar-panels-18393.html https://sciencing.com/toxic-chemicals-solar-panels-18393.htm... [2] https://www.dailymail.co.uk/news/article-1241872/EXCLUSIVE-Inside-Chinas-secret-toxic-unobtainium-mine.html https://www.dailymail.co.uk/news/article-1241872/EXCLUSIVE-I... [3] https://en.wikipedia.org/wiki/Thorium-based_nuclear_power https://en.wikipedia.org/wiki/Thorium-based_nuclear_power

dang 8y ago

Maybe so, but can you please not post unsubstantive comments to HN, especially about grand divisive topics? It leads to much less specific and much less interesting discussion. https://news.ycombinator.com/newsguidelines.html https://news.ycombinator.com/newsguidelines.html