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Science Technology

Thorium Fuel Has Proliferation Risk 239

Capt.Albatross writes "Thorium has attracted interest as a potentially safer fuel for nuclear power generation. In part, this has been because of the absence of a route to nuclear weapons, but a group of British scientists have identified a path that leads to uranium-233 via protactinium-233 from irradiated thorium. The protactinium separation could possibly be done with standard lab equipment, which would allow it to be done covertly, and deliver the minimum of U233 required for a weapon in less than a year. The full article is in Nature, but paywalled."
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Thorium Fuel Has Proliferation Risk

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  • by dywolf ( 2673597 ) on Thursday December 06, 2012 @11:14AM (#42203795)

    Still seems lower than the traditional route. And (FTA) instead of using a special facility to directly bombard/convert the thorium into fissible U233 in a short time, they just let the stuff sit for a month and decay into U233 naturally. And the article states that using the wait-to-decay method, theres also fewer/less radiotoxic byproduct, so it seems like a cheaper/safer method to start with.

    They still turn it into U233, the bomb stuff. just a difference in timescale, facility and method. So there was always a weapon risk.

    the whole "low prolfieration" thing just came from theoretically being able to spot the facilities doing the converting...though I think leaving the stuff sitting around and waiting for it to decay would also be theoretically somewhat simple to detect.

    All in all, it seems like waiting for it to decay naturally is better, unless the ratio of fissible material is significantly worse, sufficient to outweigh the fewer toxic byproducts thing..

  • by Anonymous Coward on Thursday December 06, 2012 @11:17AM (#42203833)

    that should have been

    The US detonated a U-233 bomb in Operation Teapot "MET" in 1955. The U-233 was bred from thorium.

  • by dywolf ( 2673597 ) on Thursday December 06, 2012 @11:19AM (#42203853)

    there was always a weapons risk, cause the thorium still goes to U233. The idea they couldnt make bombs from it wasnt really that they couldnt make bombs, but that they couldnt HIDE that they were doing it cause of the facilities needed to convert the thorium into fuel (in reality, how hard is it to bury construction). The ratio of source to fuel is still pretty high though (233:1 !!), so you still need lots of room to store it while it decays naturally. Seems like you'd still want to bury it/hide it (leaving construction tell tales) as just leaving it in a random warehouse to decay would be easily detectable by any radiological sniffers.

    So really not much changes with this new information. Except for the fat that letting it decay naturally has fewer toxic byproducts, which seems like a win regardless.

  • by ShanghaiBill ( 739463 ) on Thursday December 06, 2012 @11:48AM (#42204145)

    Radium (88 Ra) is a solid and shouldn't be affected by ventilation. Do you mean Radon (86 Rn)?

    Radium decays into radon. If you have a chunk of radium in a room, the radon gas will build up without ventilation.


  • Re:However (Score:5, Informative)

    by Andy Dodd ( 701 ) <{atd7} {at} {}> on Thursday December 06, 2012 @11:51AM (#42204185) Homepage

    Read TFA.

    Most U-233 that comes out of a reactor is formed by protactinium-233 decay.

    While U-232 and U-233 are nearly impossible to separate (which is why Thorium has been considered to be proliferation-resistant), protactinium-233 is very easy to separate chemically, and leads to nearly pure U-233.

  • by EuNao ( 1653733 ) on Thursday December 06, 2012 @02:47PM (#42206291) Homepage

    U233 created in a thorium reactor will be poisoned with U232 at about 0.4 percent (very dependent on design, but this is an good example of the kind of mix you will see). Even if you segment the protactinium, you are still going to have some U232 in the mix. This can not be chemically separated, and separating the isotopes of something that is hot borders on the insane. U232 has a decay chain that emits a 2.9 MeV gamma ray, and its pretty hot as far as how fast it will decay (Half life of 69 years if I remember right). It decays to Th-228 and in like 2 years into Ti-208 + nasty gamma. Very nasty stuff that will really ruin your day, and any electronics in your nuclear weapon in a hurry. You would be stupid to pick this as a nuclear fuel for a weapon, when you could just make plutonium like anyone with any sense would do. You just put some natural uranium in neutron flux of a light water reactor, wait a month or so, and separate the plutonium. Simple well known technology that works, not some crazy possibility that some PhD dreamed up because he wants to prove a point. Sure you could do it, if your an idiot who wants to make your life really hard and you have a death wish.

    Also if you are running a thorium breeder reactor you are running so close to break even on neutrons so if you remove Uranium from the cycle your ability to maintain reactor criticality will disappear. Also you have the same problem if you try and use the neutron flux to make plutonium it wouldn't work. Thorium reactors are shitty for making bombs, that is why we don't have them even though they are awesome technology that would solve so many energy problems. Thorium has little risk of being used to make bombs, and if someone is idiotic enough to do it they will die of gamma poisoning way before they have enough fuel for bombs.

  • by schroedingers_hat ( 2449186 ) on Thursday December 06, 2012 @08:58PM (#42211127)
    I'd classify myself as much a science nerd as computer nerd (if not more). And I know plenty of physicists who you could at a stretch call nuclear (mostly more along the lines of quantum) who read it frequently.
    Also I was under the impression getting 233 from a thorium reactor was rather old news, and the gamma emissions would ruin your day if you actually tried to build a bomb with it.

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