3 ms·

There are reactor designs that can't be used to make weapons, and when they fail, passive systems prevent meltdown.

by goda90 7y ago

acidburnNSA 7y ago
Not that I'm aware of. All reactors, bar none, require safeguards to prevent the owner from making weapons-usable material on the sly. Civilian nuclear is a fairly impractical and round-about way to get weapons material (just use centrifuges... way easier), but if you think it's easier to get a nuke than a centrifuge, or if you are a corrupt leader who takes over a country that has nukes, you can generally make some pretty good U-233 or Pu-239 with any nuclear reactor. Yes, even Thorium reactors (they're the ones that make U-233). China, India, USA, Russia, France, UK, Pakistan, and Israel already have nuclear weapons. If you look at the fraction of world energy that that set of countries and their collective military allies uses (nevermind Israel), you can feel pretty good about transitioning more to nuclear even given a non-zero risk of proliferation.
- garmaine 7y ago
  Thorium reactors can’t make weapons grade material. It’s just not part of the process. Thorium is also more abundant and easier to work with. The only reason why we have an uranium/plutonium nuclear industry is because those fuels permit dual-purpose (weapons generating) designs. Now it is just industrial* inertia. Edit: *industrial and regulatory.
  - acidburnNSA 7y ago
    Incorrect. Thorium reactors work by putting Th-232 into a neutron field, where it doesn't fission, but rather it absorbs neutrons to become unstable Th-233, which beta-decays into Pa-233 with a half-life of 21 minutes. Then Pa-233 in turn beta-decays to Uranium-233 with a half-life of 26.8 days. U-233 is fissile nuclear fuel, so when a neutron hits it, it will fission and release nuclear energy. All thorium-fueled reactors use this chain of events. But there's a problem. Pa-233 is a strong parasitic neutron absorber. So when it's sitting there for 26.8 days, if it were still in the nuclear core it would poison the chain reaction. So what people plan to do is to pull it out of the core chemically and put it into a holding cell outside the neutron flux where it can decay to U-233 in peace. Then the U-233 is added back to the core as it arrives. The U-233 is a potent nuclear weapons material and can be extracted from the decay tank in what are called in the non-proliferation industry "Significant Quantities". Faced with this issue, the ORNL folks created the Denatured MSR project in the death throes of the MSBR program (~1960s) which had U-238 mixed in to denature the WG U-233. Of course, then they were producing plutonium... The general claim is that U-232 is also produced in trace quantities, which has Tl-208 way down its decay chain, which emits a massive 2.6 MeV gamma ray that's hard to shield. Since it's way down the decay chain and U-232 has a 69 year half-life, every time you chemically purify your uranium you have pretty small amounts of gamma emitters. So you can purify, assemble a weapon, and drop it in a few weeks without worrying too much about Tl-208. The thorium-cant-make-bombs thing is a total myth. All nuclear reactors need safeguards, even thorium-fueled ones. This is doable and should not prevent us from making more carbon-free energy with any kind of nuclear reactor. More abundant: meh, not really. There's uranium dissolved in seawater in vast, practically infinite quantities. Easier to work with: definitely not. Higher melting temperatures for ceramics make solid-fuel thorium harder to fab, and the fluid fuel stuff is int he R&D stage. It also leads to lower-density fuels, which are crappier neutronically.
    - garmaine 7y ago
      I’m not aware of any practical nuclear weapon design using U-233. Can you cite one? The tests I’m aware of appear to be inconclusive as to whether U-233 works as weapons material. They seem to have resulted in a fissle or very low yield device, have significant purification problems, and were dropped as a research pathway by all nuclear powers that worked with it.
      - acidburnNSA 7y ago
        Yes: The classic uranium gun-type weapon design works beautifully with U-233. Very low spontaneous fission, very excellent neutronics. U-233 is unequivocally excellent weapons material. That's undebated fundamental nuclear physics. A Significant Quantity of U-233 is defined as 8 kg, better than U-235! [1] The folks down at Los Alamos aren't messing around. [1] https://permalink.lanl.gov/object/tr?what=info:lanl-repo/lareport/LA-UR-11-03368 https://permalink.lanl.gov/object/tr?what=info:lanl-repo/lar... Just read this: http://fissilematerials.org/library/sgs09kang.pdf http://fissilematerials.org/library/sgs09kang.pdf

There are reactor designs that can't be used to make weapons, and when they fail, passive systems prevent meltdown.

by goda90 7y ago

There are reactor designs that can't be used to make weapons, and when they fail, passive systems prevent meltdown.

Not that I'm aware of. All reactors, bar none, require safeguards to prevent the owner from making weapons-usable material on the sly. Civilian nuclear is a fairly impractical and round-about way to get weapons material (just use centrifuges... way easier), but if you think it's easier to get a nuke than a centrifuge, or if you are a corrupt leader who takes over a country that has nukes, you can generally make some pretty good U-233 or Pu-239 with any nuclear reactor. Yes, even Thorium reactors (they're the ones that make U-233). China, India, USA, Russia, France, UK, Pakistan, and Israel already have nuclear weapons. If you look at the fraction of world energy that that set of countries and their collective military allies uses (nevermind Israel), you can feel pretty good about transitioning more to nuclear even given a non-zero risk of proliferation.

garmaine 7y ago
Thorium reactors can’t make weapons grade material. It’s just not part of the process. Thorium is also more abundant and easier to work with. The only reason why we have an uranium/plutonium nuclear industry is because those fuels permit dual-purpose (weapons generating) designs. Now it is just industrial* inertia. Edit: *industrial and regulatory.
- acidburnNSA 7y ago
  Incorrect. Thorium reactors work by putting Th-232 into a neutron field, where it doesn't fission, but rather it absorbs neutrons to become unstable Th-233, which beta-decays into Pa-233 with a half-life of 21 minutes. Then Pa-233 in turn beta-decays to Uranium-233 with a half-life of 26.8 days. U-233 is fissile nuclear fuel, so when a neutron hits it, it will fission and release nuclear energy. All thorium-fueled reactors use this chain of events. But there's a problem. Pa-233 is a strong parasitic neutron absorber. So when it's sitting there for 26.8 days, if it were still in the nuclear core it would poison the chain reaction. So what people plan to do is to pull it out of the core chemically and put it into a holding cell outside the neutron flux where it can decay to U-233 in peace. Then the U-233 is added back to the core as it arrives. The U-233 is a potent nuclear weapons material and can be extracted from the decay tank in what are called in the non-proliferation industry "Significant Quantities". Faced with this issue, the ORNL folks created the Denatured MSR project in the death throes of the MSBR program (~1960s) which had U-238 mixed in to denature the WG U-233. Of course, then they were producing plutonium... The general claim is that U-232 is also produced in trace quantities, which has Tl-208 way down its decay chain, which emits a massive 2.6 MeV gamma ray that's hard to shield. Since it's way down the decay chain and U-232 has a 69 year half-life, every time you chemically purify your uranium you have pretty small amounts of gamma emitters. So you can purify, assemble a weapon, and drop it in a few weeks without worrying too much about Tl-208. The thorium-cant-make-bombs thing is a total myth. All nuclear reactors need safeguards, even thorium-fueled ones. This is doable and should not prevent us from making more carbon-free energy with any kind of nuclear reactor. More abundant: meh, not really. There's uranium dissolved in seawater in vast, practically infinite quantities. Easier to work with: definitely not. Higher melting temperatures for ceramics make solid-fuel thorium harder to fab, and the fluid fuel stuff is int he R&D stage. It also leads to lower-density fuels, which are crappier neutronically.
  - garmaine 7y ago
    I’m not aware of any practical nuclear weapon design using U-233. Can you cite one? The tests I’m aware of appear to be inconclusive as to whether U-233 works as weapons material. They seem to have resulted in a fissle or very low yield device, have significant purification problems, and were dropped as a research pathway by all nuclear powers that worked with it.
    - acidburnNSA 7y ago
      Yes: The classic uranium gun-type weapon design works beautifully with U-233. Very low spontaneous fission, very excellent neutronics. U-233 is unequivocally excellent weapons material. That's undebated fundamental nuclear physics. A Significant Quantity of U-233 is defined as 8 kg, better than U-235! [1] The folks down at Los Alamos aren't messing around. [1] https://permalink.lanl.gov/object/tr?what=info:lanl-repo/lareport/LA-UR-11-03368 https://permalink.lanl.gov/object/tr?what=info:lanl-repo/lar... Just read this: http://fissilematerials.org/library/sgs09kang.pdf http://fissilematerials.org/library/sgs09kang.pdf