50 ms·

yes. a recent nature article pointed out how thorium can be used to make uranium-233 which can be used to make nuclear weapons.[1] (see the conclusions section

by pkrein 14y ago

yes. a recent nature article pointed out how thorium can be used to make uranium-233 which can be used to make nuclear weapons.[1] (see the conclusions section at the end of the article) here's a more detailed explanation: the "old" idea before this nature article was that the uranium-233 produced in thorium reactors would be inevitably mixed with uranium-232 (which isn't useful for making bombs). but the nature article pointed out that the real decay path is thorium-233 --> protactinium-233 --> (uranium-232 AND uranium-233), and that by separating the protactinium-233 from the thorium reactor's neutron flux after 1 month, you can ensure that the protactinium-233 converts to uranium-233 instead of uranium-232.[2] ... step 3 you can make a weapon. [1] http://www.nature.com/nature/journal/v492/n7427/full/492031a.html http://www.nature.com/nature/journal/v492/n7427/full/492031a... (sorry for the paywall :( ) [2] http://en.wikipedia.org/wiki/Thorium_fuel_cycle http://en.wikipedia.org/wiki/Thorium_fuel_cycle

ScotterC 14y ago
But this isn't practical in reality. First of all, you need a core of U-233 to start the process but once you start you're adding thorium at different points in time so the fuel slurry is going to be always a mix of thorium, protactinium, u-232, u-233 and other various products which makes extracting anything a royal pain. There's much easier ways of isolating weapons grade uranium instead of trying to extract it from a ongoing fuel process.
- slurgfest 14y ago
  The question isn't whether there are easier ways of producing, but whether the thorium reactor doesn't provide better concealment for producing what would bring unwanted attention when done in the 'easier' way.
  - stcredzero 14y ago
    If you're trying to conceal what you're doing, it would be best by far to avoid U-232 being involved in the process.
- jhartmann 14y ago
  1) If you take away Uranium from a thorium reactor you will rather quickly lose criticality, so you won't be making any new protactinium. Thorium breeders run very close to steady state, and only make a very small fraction of fuel more then they need. 2) I'm pretty sure there is a rare reaction that you will get protactinium-232, which has a much shorter half life the protactinium-233 (about a day instead of about a month) but it can't be chemically separated. It will decay to U-232. The nature article is alarmist, and not practical. It would only make sense if you had a separate neutron source that was not a thorium breeder, and probably will still have a good amount of U-232. Since you have a neutron source (probably a light water reactor) why you wouldn't use the extremely well understood methods to make plutonium from U-238 is beyond me. You quite literally just need to put uranium metal in the neutron flux for 1 month and chemically separate out the plutonium. Much easier, if I was designing a nuclear weapons program I sure as hell wouldn't pick Thorium.
tsotha 14y ago
But that means that while thorium doesn't present an obstacle to state actors in acquiring nuclear weapons, it would considerably lower the risk of theft of non-polluted U-233 by non-state actors.
- pkrein 14y ago
  as far i understand, yes. the real nasty thing about uranium-232 is that it emits highly dangerous gamma radiation [1], which is extremely unhealthy==difficult==expensive to handle. if i understand correctly, the gamma radiation also makes it much easier to detect from afar, making stealth difficult. [1] http://en.wikipedia.org/wiki/Isotopes_of_uranium#Uranium-232 http://en.wikipedia.org/wiki/Isotopes_of_uranium#Uranium-232
  - jhartmann 14y ago
    It will also toast the electronics in your nuclear weapon, essentially making a weapon with a considerable enough portion of U-232 impossible.
mseebach 14y ago
It's only tangentially relevant that a given reactor type can be used to make nuclear weapons. Yes, it means that there are states on the planet that can't be trusted with them, so be it. But there are plenty of countries that already have nuclear weapons and/or are stable and transparent enough that they can be trusted to submit to inspections - these could start Thorium projects and the world wouldn't be worse off on the proliferation front for.
InclinedPlane 14y ago
Also, any fission reactor is a proliferation risk, because it will be a strong neutron source. Simply put hunks of natural Uranium around the core of your reactor and replace it on an appropriate schedule and you'll breed weapons-grade Plutonium which can be easily chemically extracted. It's just may not be as efficient as other methods.
KitemanSA 14y ago
FOLLOW THE NUMBERS!!! U235 & Pu239 bombs extant ... ~20,000 U233 bombs extant ... ZERO Seems pretty conclusive. It is MUCH easier to make bombs the way everyone always has than to put your lives on the line fiddling with U233.

by pkrein 14y ago

ScotterC 14y ago

But this isn't practical in reality. First of all, you need a core of U-233 to start the process but once you start you're adding thorium at different points in time so the fuel slurry is going to be always a mix of thorium, protactinium, u-232, u-233 and other various products which makes extracting anything a royal pain. There's much easier ways of isolating weapons grade uranium instead of trying to extract it from a ongoing fuel process.

slurgfest 14y ago
The question isn't whether there are easier ways of producing, but whether the thorium reactor doesn't provide better concealment for producing what would bring unwanted attention when done in the 'easier' way.
- stcredzero 14y ago
  If you're trying to conceal what you're doing, it would be best by far to avoid U-232 being involved in the process.
jhartmann 14y ago
1) If you take away Uranium from a thorium reactor you will rather quickly lose criticality, so you won't be making any new protactinium. Thorium breeders run very close to steady state, and only make a very small fraction of fuel more then they need. 2) I'm pretty sure there is a rare reaction that you will get protactinium-232, which has a much shorter half life the protactinium-233 (about a day instead of about a month) but it can't be chemically separated. It will decay to U-232. The nature article is alarmist, and not practical. It would only make sense if you had a separate neutron source that was not a thorium breeder, and probably will still have a good amount of U-232. Since you have a neutron source (probably a light water reactor) why you wouldn't use the extremely well understood methods to make plutonium from U-238 is beyond me. You quite literally just need to put uranium metal in the neutron flux for 1 month and chemically separate out the plutonium. Much easier, if I was designing a nuclear weapons program I sure as hell wouldn't pick Thorium.

tsotha 14y ago

But that means that while thorium doesn't present an obstacle to state actors in acquiring nuclear weapons, it would considerably lower the risk of theft of non-polluted U-233 by non-state actors.

pkrein 14y ago
as far i understand, yes. the real nasty thing about uranium-232 is that it emits highly dangerous gamma radiation [1], which is extremely unhealthy==difficult==expensive to handle. if i understand correctly, the gamma radiation also makes it much easier to detect from afar, making stealth difficult. [1] http://en.wikipedia.org/wiki/Isotopes_of_uranium#Uranium-232 http://en.wikipedia.org/wiki/Isotopes_of_uranium#Uranium-232
- jhartmann 14y ago
  It will also toast the electronics in your nuclear weapon, essentially making a weapon with a considerable enough portion of U-232 impossible.

mseebach 14y ago

It's only tangentially relevant that a given reactor type can be used to make nuclear weapons. Yes, it means that there are states on the planet that can't be trusted with them, so be it. But there are plenty of countries that already have nuclear weapons and/or are stable and transparent enough that they can be trusted to submit to inspections - these could start Thorium projects and the world wouldn't be worse off on the proliferation front for.

InclinedPlane 14y ago

Also, any fission reactor is a proliferation risk, because it will be a strong neutron source. Simply put hunks of natural Uranium around the core of your reactor and replace it on an appropriate schedule and you'll breed weapons-grade Plutonium which can be easily chemically extracted. It's just may not be as efficient as other methods.

KitemanSA 14y ago

FOLLOW THE NUMBERS!!! U235 & Pu239 bombs extant ... ~20,000 U233 bombs extant ... ZERO Seems pretty conclusive. It is MUCH easier to make bombs the way everyone always has than to put your lives on the line fiddling with U233.