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Private Thorium reactors?

  1. Jan 18, 2016 #1
    Since thorium is not regulated as far as I know (though also not exactly commercially available, because of how cheap it is, and all that) and it's not particularly dangerous, even in a reactor, is there anything (other than the price/knowledge) stopping individuals from building small thorium reactors?

    Would I for example, be allowed to make a mini-reactor using thorium? I assume anything big enough to generate a significant amount of power, would run into legal issues, but what about something that generates a small amount, just to light a light bulb or something like that for novelty/demonstration, per-say?
  2. jcsd
  3. Jan 18, 2016 #2
    What jurisdiction?
    Here in Sweden, we are even obliged to pay for permission for our educational 35 kV/1mA x-ray tube.
  4. Jan 18, 2016 #3


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    Obviously, none of this is legal advice, but in Australia, that'd be ARPANSA and probably ASNO. You'd probably also be in violation of the Environmental Protection & Biodiversity Conservation Act, and depending on your state, you'd very likely be in trouble at a state level as well.

    In the US, the cautionary tale would have to be David Hahn, the "radioactive boy scout". https://en.wikipedia.org/wiki/David_Hahn In that case, the police, the FBI, the Nuclear Regulatory Commission as well as the EPA were the ones dealing with him.

    Radioactivity is not something you want to mess with lightly, and a thorium reactor will produce lots of dangerous radioactive waste. This is why every country will have regulations around this.
  5. Jan 18, 2016 #4
    But don't most of those only cover gamma rays? Where as thorium releases alpha rays, which can be blocked by human skin, and are as such not (generally) dangerous (large exposure, from more than a kilo has been shown to increase risks of certain cancers). That's why its perfectly legal to own a chunk of thorium (though I'd assume you'd be put on some lists if you start buying the stuff), and not uranium.
  6. Jan 18, 2016 #5


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    "Those" as in the regulatory agencies I mentioned? No, they cover all kinds of ionizing (and in the case of ARPANSA, non-ionising) radiation.
    There is a significant risk of contamination if you produce any dust at all, and if you breathe in alpha-emmitters, it's not good. Further, using a thorium reactor will produce fission by-products which will be gamma emitters (and alpha, and beta) and will pose significant risk. People talk about thorium reactors being better from a waste standpoint because the waste becomes safe in a few hundred, not thousand of years, but that still doesn't make it safe for a hobbyist.

    Further, presuming you're in the US, thorium is absolutely regulated by the NRC. http://www.nrc.gov/materials/srcmaterial.html
  7. Jan 18, 2016 #6
    Okay, thank you for the explanation!
  8. Jan 18, 2016 #7


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    There are regulations regarding the possession of radioactive material and the development of a nuclear reactor. Th-232, like U-238, has a very long half life and is an alpha-emitter. One could possess a small amount, although I'm not sure what the limit is.

    However, once one starts configuring material or a nuclear reactor, that becomes an entirely different issue. It would be assumed that a nuclear reactor using thorium or uranium would be using a controlled fission process, and that system would be highly regulated. One would need a source of neutrons, and neutron sources and nuclear reactors are strictly regulated. Even a power source using radioactive decay would be regulated since a radioisotopic thermoelectric generators (RTG) will produce radiation that must be shielded. Most are based on Pu-238, but they could use other alpha- or strong beta-emitters, and there is usually gamma radiation involved.

    https://solarsystem.nasa.gov/rps/rtg.cfm (most use Pu-238)
  9. Jan 19, 2016 #8


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    I'd just like to point out that "thorium reactors" actually require fissile U-233, U-235, or Pu-239 in order to function. Thorium is merely the breeding material - you cannot create a reactor using thorium alone.
  10. Jan 19, 2016 #9
    Possession of Thorium is regulated in the US as a "source material." Here's from 10CFR part 40.

    Source Material means: (1) Uranium or thorium, or any combination thereof, in any physical or chemical form or (2) ores which contain by weight one-twentieth of one percent (0.05%) or more of: (i) Uranium, (ii) thorium or (iii) any combination thereof. Source material does not include special nuclear material.

    Special nuclear material means: (1) Plutonium, uranium 233, uranium enriched in the isotope 233 or in the isotope 235, and any other material which the Commission, pursuant to the provisions of section 51 of the Act, determines to be special nuclear material; or (2) any material artificially enriched by any of the foregoing.
  11. Jan 19, 2016 #10


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    A little more info - the idea of "safe, clean, easy thorium reactors" is a bit of a misconception. Thorium breeder reactors work pretty much the same as conventional reactors. The thorium fuel cycle as some advantages but there are also drawbacks, and to date the advantages haven't been such a draw to make all the work necessary to implement them worth doing.

    Nuclear reactors require a extensive knowledge in many areas to build and operate. It's not something a hobbyist could do in their garage for fun.
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