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Fission to make gold or silver

  1. Aug 2, 2012 #1
    What's stopping entrepreneurs from using fission - taking mercury, for example, or any heavier element for gold/silver - and creating gold and silver from it? Do you think there will come a day when this is commercially viable? Any guesses when?
     
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  3. Aug 3, 2012 #2

    QuantumPion

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    There are no decay chains which end with stable gold or silver. The only way to produce them is by bombarding other isotopes with protons or neutrons. This is very expensive - many orders of magnitude more expensive than the resulting material is worth.

    You could bombard Hg-196 with neutrons to make Hg-197, which then decays to Au-197. However Hg-196 is only 0.15% of all mercury and neutrons aren't free either. Even in a high flux nuclear reactor the production rate of Hg-197 would be miniscule compared to the value of gold you could retrieve.
     
  4. Aug 3, 2012 #3

    mfb

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    Fission induced by high-energetic particles? You cannot control the fission reaction - you would get a mixture of a lot of different isotopes from different elements, many of them would be radioactive. In addition, the acceleration of the particles would be too expensive for the tiny amount of gold/silver you can get. Even with 100% efficiency everywhere, the electric power required for the acceleration is more expensive than the material you can produce with it.
     
  5. Aug 3, 2012 #4

    arivero

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    Hg 201 alfa to Pt 197 beta to Au 197 seems a decay chain to me.
     
  6. Aug 3, 2012 #5

    QuantumPion

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    Hg-201 does not undergo alpha decay, is stable.
     
  7. Aug 3, 2012 #6

    QuantumPion

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    I ran a quick sample case in ORIGEN-ARP with regular PWR fuel mixed with natural Hg. After approximately 1.5 years of full power operation Au-197 reaches its maximum concentration after which it begins to absorb more neutrons than are produced and its concentration decreases. The amount of gold created is approximately 10 grams per MTU per 1 w/o initial Hg. There is no way that is worth the loss of fuel economy, especially considering the cost of reprocessing. The U-235 you have to waste to generate the extra neutrons is far more valuable than the gold you end up with.
     
  8. Aug 3, 2012 #7

    arivero

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    Hg 201 is metastable, not stable. The sum of masses of Pt 197 and alpha is lower than the mass of Hg 201, if I have checked correctly the tables -but please doublecheck yourself-. That should mean that you do not need to waste neutrons and the gamma energy comes back to you as heat.

    I have never used ORIGEN ARP. Can it emulate these conditions, pure 201 Hg with no neutron absortion?
     
    Last edited: Aug 3, 2012
  9. Aug 3, 2012 #8

    QuantumPion

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    ENDF does not have any photonuclear or decay data for Hg-201. Just because a reaction has a positive Q-value does not necessarily mean it is physically possible. I'm not familiar with (λ,α) reactions.
     
  10. Aug 3, 2012 #9

    mfb

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    In other words, you lose a significant fraction of the energy, even if it is possible.

    200.970302 u - 196.967340 u - 4.0026032542 u = 334keV (numbers from Wikipedia)
    This is equivalent to 45kWh/g gold. Any significant gold production would handle power comparable to power plants, regardless of the efficiency of the production.
     
  11. Aug 3, 2012 #10

    arivero

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    Yep I guess that this is the general problem when answering to this question :-( It is not easy to find empirical data, and it is not easy to be sure about how some gamma pressure should enhance, if it does, the tunneling rate. But it is important,imo, to stress that the usual answer "It needs to much energy" is wrong; with a positive Q-Value, one can not tell that it is about energy.

    Of course, for the particular formulation of the question here, there is a trivial answer, as the OP asks about "fission" and not "nuclear reactions". In this case, it is OK to tell that the fission products are very scattered in the periodic table and unmanageable.

    For nuclear reaction, I think the answer is more subtle.

    - First, there is only a few suitable reactions (plus few data on them, plus few researchers who could be interested... but in any case, only a few suitable)
    - Second, suitable reactions are going to be across elements with nearby masses, this is different from fission. And elements with similar mass have, in first order of approximation, similar production rates in stellar process and then, barring chemical opportunities, similar abundance. Most Hg, for instance, comes from two or three extraction sites.
    - Third, the ambiental risk of some of the suitable reactions goes even worse. Take Hg; its extraction and chemical separation is even forbidden in some parts of the world. Put some excess in water and kill yourself in the long run. Add the costs and risk of preparation, with isotope separation and all that, and the cost of late purification. Join all of it to the second point, and break-even becomes unfeasible
     
  12. Aug 3, 2012 #11

    arivero

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    Yeah, but the first scenario calculated by quantumpion was to use radiation inside a power plant already. So now you have a Hg powered power plant :biggrin:. Really I speculate that most of the energy is going to be heat because most of the energy is going to be in the alpha, which will surely dissipate in collisions. There is also the beta, from the intermediate Pt, and then there are surely some secondary gammas around. Not sure if some of this can be used to keep the reaction running... is (α, 2 α) with enough cross-section? Surely not.

    In any case let me note that it is funny to notice that the problem is not how to put energy in (as usually it is told in popsci articles) but how to get rid of the energy if you are able to make it to work :cool:
     
    Last edited: Aug 3, 2012
  13. Aug 3, 2012 #12
    Thanks. I don't know much about chemistry/physics - only at the high school level. I'm just trying to understand, as an investor, whether or not it is 1) feasible to create gold and silver at economical levels and 2) if it is not, do you think it will be possible in the near future. When would you guess, that nuclear reactors could replace mines, if possible at all.
     
  14. Aug 3, 2012 #13

    QuantumPion

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    1) no
    2) never.
     
  15. Aug 3, 2012 #14

    arivero

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    I agree with QP. Let me add, if you have been told otherwise, you are been driven towards a scam.
     
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