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The Subject of Iranian Nuclear Program (yes, physics related)

  1. Feb 2, 2012 #1
    Ok, so the latest headline from RussiaToday has prompted me to finally inquire about the the nuclear program issue. We've all heard about how Iran claims their nuclear program is for the alleged peaceful purposes. A recent report has stated that Iran officially has "enough radioactive material to successfully produce not just one, but four nuclear bombs". Now perhaps I am missing out on a key fact here which is why I feel like I am the only one who brings the following matter.

    Is there a difference between the uranium used for bombs and for other things? A difference in the end result? Or perhaps a subtlety in the refining process that makes it ambiguous to claim the usage? Are there ways of analyzing the wastes produced to perhaps get insight?


  2. jcsd
  3. Feb 2, 2012 #2


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    There is a difference between 'reactor grade' (RG) and 'weapons grade' (WG) enrichments. Conventional nuclear power reactors are limited to 5% enrichment, whereas WG usually use an enrichment of 90+%. Technically, above 70% would be considered WG.

    To go from 5% to 90% simply means continuing the enrichment process.

    Some research reactors have used 90% enriched fuel, but they are special cases. Furthermore, most of the special reactors have had their enrichments reduced to about 20%.

    Some special test fuel has enrichments > 5% for faster accumulation of burnup, or to run longer. However, such cases are rather unique these days.

    Commercial companies supplying the nuclear industry and the utilities are required to report their inventories (including enrichments) of fissile material. Iran has not necessarily been so transparent, and there are concerns that they have a clandestine program to enrich well beyond 20%.
  4. Feb 2, 2012 #3


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    A nuclear bomb requires several kilograms of highly enriched (90% is good) uranium 235 or plutonium. See http://en.wikipedia.org/wiki/Uranium
    The latter is bred in nuclear reactors, so not yet an issue for Iran.
    U 235 is a rare isotope, about 99% of natural uranium is U238, so it takes a lot of work to extract the U235.
    Power reactors run on enriched uranium, about 5% U235 usually.
    Iran has noted that it has enriched some uranium to 20%, which is much more that they need for reactor fuel. There are apparently some civil applications that use more highly enriched uranium, but of course the suspicion also exists that Iran is smoothing the way for a nuclear bomb program.
    Seen that no nation which has tried has failed to make a nuclear bomb, not even an impoverished country such as North Korea, Iran is certain to succeed if they try.
    The major impediment is political, not technical. In that sense, the arguments about the level of enrichment are scholastic, interesting but not meaningful.
    Indeed, it would make perfect sense for Iran to calm the current tensions and ease up on their stance, as the true value of their current program is to train the indigenous talent that will eventually allow the leadership to go nuclear within months at any time they choose.
  5. Feb 2, 2012 #4
    I hear them citing medical usage often. Do medically based uses truly have exceptional conditions requiring highly enriched uranium, or is this argument as good as any other (apart form holding a rosy political image...)?
  6. Feb 2, 2012 #5
    Iran has a lot of oil and natural gas. In fact it probably has so much of byproduct gas from oil drilling that it might be still simply flaring it. In the foreseeable future for Iran it does not make *economic* sense to build nuclear power plants: it's far cheaper to build and use gas-fired ones.
  7. Feb 3, 2012 #6
    It may be that exporting oil and natural gas outweighs the cost of replacing their fossil fuel plants with nuclear plants. In other words, it's more profitable for them to switch to nuclear and export their oil than it is to use the oil.
  8. Feb 3, 2012 #7
    OK so I know it's easy to start getting into the politics of this but perhaps we could FIRST still settle some more of the physics related questions, simply by virtue of being a "physics forum" lol. Does anyone have any knowledge in the field of nuclear medicine to answer my latest question in this thread?
  9. Feb 3, 2012 #8

    jim hardy

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    ""Do medically based uses truly have exceptional conditions requiring highly enriched uranium, or is this argument as good as any other (apart form holding a rosy political image...)?""

    only medical use i know of for uranium, whether enriched or not, is in making isotopes for nuclear medicine. Short lived isotopes like technecium used for cardiac stress test have to be made shortly before they are used and my school's research reactor occasionally made some. It was an old reactor around 90% enriched (oralloy).

    that's sum total of my meager knowledge.

    i think there's a device called "Fusor" manufactured by Chrysler back in 60's that can make a beam of neutrons for same purpose. I read of it once but never saw one.

    i hope this primes the information pump for you.

    Interesting thought though -- "medical HEU" ?
    Sounds like something out of California, not Iran.
    where do i get a prescription?

    old jim
  10. Feb 3, 2012 #9


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    It is probably not the uranium that has medical uses. Some legitimate isotopes for medical use can be generated by special assemblies inside a reactor core's neutron fields. It is also possible to breed plutonium this way. It is a political question as to which is the case with Iran. Radioiodine, Cobalt 60, and other isotopes are licensed and controlled for medical and/or commercial uses.
  11. Feb 3, 2012 #10
    So basically the last two posts imply that:

    1. If uranium is used for medical uses, it doesn't first of all require enrichment.
    2. The isotopes that can be obtained from uranium could be obtained in other ways/from other materials.

    Is that right? But one more thing - in regards to #2, would they be able to claim that using uranium is cheaper than the other methods?
  12. Feb 3, 2012 #11

    jim hardy

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  13. Feb 3, 2012 #12


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    Uranium is not used for medical uses. It is a heavy metal, like lead, arsenic, thallium, and is essentially toxic.

    Uranium is used as a fuel in a nuclear reactor, and is the source of neutrons. Neutrons are used to activate elements to make radioisotopes. Isotope X(Z, A) becomes isotope X(Z, A+1) upon absorbing a neutron.

    Tc-99 is formed from Mo-98, which absorbs a neutron, become Mo-99, which decays to Tc-99. Mo-94 through Mo-97 are stable, so eventually, they'll become Mo-98 in a neutron field.

    If one uses a nuclear reactor for radionuclide production, one would bump up the enrichment to compensate for the absorption of neutron in radioisotope production. However, such reactors don't need enrichments well beyond 20%.

    HEU uses can be found here in - IAEA-TECDOC-1452 -
    Management of high enriched uranium for peaceful purposes: Status and trends
  14. Feb 4, 2012 #13
    Hmm. Well I think I've got it all straight now...thanks everyone for the input.

    Thanks astronuc for that last link. Look forward to reading it.
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