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Plutonium Production Pathway

This is a WARNING sort of post....
 
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It has occurred to me that there is a potential problem with respect to "nuclear proliferation". I am pointing it out so that steps might be taken to try to prevent that problem from becoming real.

It is well known that if you take an atom of Uranium-238 and add a neutron to it, it becomes U-239, which, because of radioactive decay, becomes Neptunium-239 and then Plutonium-239 (all within a few days). It is not hugely difficult to make a nuclear explosive device from some (classified quantity of) Pu-239 --every nation that has tried appears to have succeeded on the first attempt-- and so the international community tries to thoroughly control the various ways in which uranium gets used.

Meanwhile, some other chemical elements don't appear to have much in the way of "international controls", and the two elements I wish to bring to your attention are Thorium and Lithium.

Almost all naturally-existing Thorium is Th-232 (and it is 3 times as abundant as Uranium), and more than 90% of Lithium is Li-7 (often the percentage is even higher, because lots of lithium has been processed to remove the other isotope, Li-6, for making hydrogen bombs).

Well, today I happened to notice that someone could take Li-7 and put it into a modest particle accelerator (modest enough that just about any mad scientist could afford one), and then bombard Th-232 with it and ....

Well, the exact reaction is Th-232 + Li-7 -> Np-239, which quickly becomes Pu-239....

Admittedly, it would take someone quite a while to bombard enough Thorium to end up with enough Plutonium to build an explosive nuclear device, which gives us a window of opportunity to see about enacting international controls to prevent some mad scientist from getting away with it.

That's all.

Vernon, Nov 27 2013

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       aren't people actually trying to create commercial small scale Thorium reactors, even car engines?
theircompetitor, Nov 27 2013
  

       I'm pretty confident all/most of these pathways are well trodden.   

       Li7, since the Castle Bravo incident, has been known to be similarly useful as a nuclear fuel as Li6. Whoops. That's an interesting story if you're interested - 15Mt yield, when predicted yield was 6Mt. Someone either got fired, or promoted over that one (but in reality, there were some horrible consequences).   

       What you might not have realised is there is a fissile fuel available as a direct product of Thorium neutron capture, that is U-233. In fact, in a reactor, it is the U-233 that is actually fissioning to produce energy, the Thorium is only the feedstock. The Americans, and some other nations ran the requisite trials of U-233 as a bomb making material many moons ago. It isn't as suitable as U-235 or Pu-239, but it does work.   

       ....So, there is already a big proliferation risk with Thorium reactors, and you don't need a particle accelerator either...   

       There are many benefits as well, but Thorium reactors are, by definition, breeder reactors of fissile fuel. Some long and hard consideration needs to be given to the potential consequences of broad utilisation of Thorium based nuclear power.
Custardguts, Nov 27 2013
  

       Yes.   

       Now …   

       While superficially attractive, the idea is unworkable. What is being described is nuclear fusion.   

       Bombarding nucleii with other nucleii with the intent of getting them to fuse is radically different from neutron bombardment. Neutrons don't interact, and the process is dependant only on the cross-section of the target nucleii and the energy of the neutrons.   

       In the process described, the Lithium nucleii will just ionize the target, rapidly shedding energy- unless the target is plasma. That's one of the reasons why fusion systems, both weapons and reactors, require plasma.   

       Say you get a lucky hit, and make an atom of Pu. What's to stop it being hit again, and transitioning into something else ?   

       The U -> Np -> Pu production cycle works because a reactor can produce and sustain a huge flux of surplus neutrons. In the Manhattan project, nanogramme quantities of Pu were produced using cyclotrons to allow evaluation of the chemistry. It was extremely slow and energetically inefficient.   

       This is not something anyone should lose sleep over.   

       U233 isn't brilliant as a fissile material. But a Thorium reactor does produce that highly desireable neutron flux. Pop a few slugs of natrural Uranium metal in your Thorium powerplant and let them cook, then drag them out and separate the Pu. Et Viola …
8th of 7, Nov 27 2013
  

       Yes. A much higher risk is someone operating some sort of brumbied-up breeder reactor producing large ammounts of raioactivated materials and putting them in dirty bombs. Ultimately, that wouldn't even be very hard to do, certainly not requiring of a complex industrial power generating plant or similar infrastructure. I'm talking something more like an underground pit with minimal automation/instrumentation, some sort of moderation and scramming system (literally, pumped water, and a pile or boron salts), a nice hot neutron source to get things started, and a lot of free time.   

       That's what I would be worried about. I wonder if any nefarious groups have seriously considered this, and/or started?
Custardguts, Nov 27 2013
  

       I'm completely aware of ALL the usual nuclear- reaction cycles for energy production. And I'm also aware that the reaction described in the main text here is an energy-consumer, not an energy- producer. The present HalfBakery category, however, doesn't specifically require that energy be produced; any sort of nuclear-related energy Idea should qualify for inclusion.   

       (But didn't I write enough to make it obvious that AFTER one makes a lot of Plutonium from Thorium and Lithium, a quite- large quantity of energy can be released, explosively?)   

       And so this Idea said nothing about energy production from the specified reaction; it is merely a Warning about the potential major mis-use of certain substances, of which Lithium is most certainly readily available, and Thorium, so far as I know, is also more- available to average folks than perhaps it should be.
Vernon, Nov 27 2013
  

       Our criticism is not based on the energy efficiency aspect, but rather on the extreme difficult of getting it to work at all in the first place.   

       // I wonder if any nefarious groups have seriously considered this, and/or started? //   

       Well, the Nazis did this in the 1940's and they are close to the gold standard for out-and-out nefariousness (the actual gold standard being, of course, the french. As usual).
8th of 7, Nov 27 2013
  

       For another and rather different Plutonium Production Pathway, start with Bismuth. 100% of natural Bismuth is Bi-209, and it is easily available (see ingedients of "Pepto-Bismol").   

       Now look at Silicon. About 25% of the Earth's crust (the average rock) is Silicon, and about 3% of Silicon is Si-30. If you extracted that and used an appropriate accelerator to jam a Silicon-30 nucleus into a Bismuth nucleus, the result is Berkelium- 239, which decays to Curium-239, which decays to Americium-239, which decays to (ta-dah!) Plutonium-239.
Vernon, Dec 06 2013
  

       //About 25% of the Earth's crust (the average rock) is Silicon,   

       Weird, about the same amount in glamour models, it's just a coincidence, isn't it?
not_morrison_rm, Dec 07 2013
  

       [not morrison rm], there is a difference between "silicon" and "silicone". The former is what I was referencing; the latter is used in the plastic surgery industry (and others).
Vernon, Dec 07 2013
  

       Stranger, there might be 25% silicon in the silicone.
wjt, Dec 07 2013
  
      
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