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Nuclear waste.

  1. Feb 3, 2006 #1
    Can the nuclear waste from nuclear reactors be used to make nuclear weapons?
    Secondly, Whats wrong in burying nuclear waste deep inside the earth or beneath the oceans? And lastly, are the hazards of nuclear waste from nuclear reactors exaggerated?
    Any help will be appriciated.:smile:
     
    Last edited: Feb 3, 2006
  2. jcsd
  3. Feb 3, 2006 #2

    Morbius

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    DeathKnight,

    In answer to your first question - it depends.

    The plutonium that is used in nuclear weapons is produced in nuclear reactors - called
    production reactors. However, those reactors are operated in a particular manner so
    that one gets the proper mixture of plutonium isotopes for bomb fuel; which is called
    "weapons-grade" plutonium.

    The DOE has released the fact that so-called "reactor grade" plutonium can be used
    to make a nuclear weapon - but it's difficult to do. A novice nuclear weapons designer
    would have trouble making a weapon from "reactor-grade" plutonium; whereas an
    experienced nuclear weapons designer knows how to do it.

    If one designs the reactor properly, one can even prevent the experienced designer
    from using plutonium from such a reactor. For example, the IFR reactor designed
    by Argonne National Lab:

    http://www.pbs.org/wgbh/pages/frontline/shows/reaction/interviews/till.html

    As Dr. Till discusses, it is IMPOSSIBLE to use the waste from the IFR to make
    into weapons. The IFR's plutonium recycle process doesn't produce the pure
    plutonium needed for weapons.

    Geological disposal - burying the waste, as you say - is what the National Academy
    of Sciences suggested in the late 1950's. There's been a lot of work on Yucca
    Mountain - but it is still a political hot potato.

    I believe we should do what the IFR does - recycle the "actinides" - i.e. plutonium and
    the other heavy isotopes back to the reactor as fuel. This can also be done by
    taking our current nuclear waste - chemically separating out the actinides - then
    blend that with fresh uranium fuel to form what is called "MOX" - "mixed oxide" fuel.
    [ The fuel is a mix of uranium oxide, plutionium oxide...]

    If one does that - then the waste that needs to be disposed of consists merely of the
    fission products - as Dr. Till and interviewr Richard Rhodes [ Pultizer Prize wiiner ]
    discuss in the Frontline interview above.

    If all you have is fission products - the longest lived fission product of any consequence
    is Cesium-137. Cs-137 has a half-life of about 30 years. In about 20 half-lives, or
    600 years; the radioactivity of the nuclear waste will be less than the radioactivity
    of the uranium that was originally dug out of the ground.

    So from 600 years on - the waste repository would pose less of a threat to humanity
    and the environment, than the uranium that is already sitting UN-MINED in the crust
    of the Earth. If the waste consisted of only fission products - the longevity of the
    waste is lessened.

    The EPA had originally promulgated regulations that regulated the performance fo the
    repository for 10,000 years. Recently, the U.S. Supreme Court struck down that limit
    and said EPA had to regulate for 250,000 years.

    I think some want the regulation to continue until every last radioactive atom has
    decayed to a stable state.

    Dr. Gregory Greenman
    Physicist
     
  4. Feb 3, 2006 #3

    mathman

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    Gold Member

    Although it is very difficult to make nuclear weapons from waste, the waste could easily be used to make "dirty" bombs. These are bombs based on conventional explosives packed with nuclear waste to create a radioactive cloud when detonated.
     
  5. Feb 3, 2006 #4
    In answer to your first question - yes. That's exactly what the North Koreans did.
     
  6. Feb 3, 2006 #5

    Astronuc

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    Ah, not quite.

    North Korea did not use nuclear waste (fission products). Rather they did what other nations possessing nuclear weapons did, they reprocessed the fuel, separating the waste (fission products) from the useful fissile Pu-239/Pu-240. The Pu-239/240 is then fabricated into metal spheres (pits) for implosive nuclear warhead. The alternative process is to use centrifuges to produced highly enriched U (U-235), which is not as effective as Pu-239.

    The waste (fission products) is radioactive, but cannot fission. As mathman correctly indicated, the waste could be used in a 'dirty' bomb in which conventional explosive are use to disperse radioactive waste over a wide area.
     
  7. Feb 4, 2006 #6
    I was just reading about transmutation. From what I have read, it seems like a very good way to deal with the long-lived radioactive waste. I've also read that during this process energy is released which can be used to produce electricity. If thats true why not US or other countries transmutaing their radioactive waste?
     
  8. Feb 4, 2006 #7

    Astronuc

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    I believe transmutation has been demonstrated in the laboratory on a very small scale. It takes are large system in order to do it economically, and that would take several years of development.

    http://apt.lanl.gov/atw/

    http://www.pnl.gov/atw/ReportToCongress/index2.html

    and alternative to transmutation by accelerator - http://www.world-nuclear.org/sym/2001/venneri.htm ( www.world-nuclear.org/sym/2001/pdfs/venneri.pdf )
    The Modular Helium Reactor has yet to be developed and built.

    http://www.cem.msu.edu/~cem181h/projects/98/nuclear/ - a reasonable overview of the situation.

    Transmutation of transuranic elements also requires partitioning or separation, which is accomplished in a reprocessing facility.

    http://www.ocrwm.doe.gov/ymp/about/reprocess.shtml

    The US has not reprocessed commercial fuel, nor defense fuel IIRC, in many years. Reprocessing was halted during the Carter administration (ca. 1977) out of concerns for proliferation or diversion of Pu-239 to weapons. Reprocessing appears to back on the table as an option in the fuel cycle.

    Then there are those who oppose the transmutation option - http://www.ieer.org/reports/transm/pressrel.html

    http://www.greenscissors.org/energy/atw.htm
     
  9. Feb 4, 2006 #8

    Morbius

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    Astronuc,

    It should be back on the table - Carter's policy didn't work.

    The USA wanted the United Kingdom, France, Japan... to stop reprocessing
    nuclear fuel. The USA really wasn't concerned about US reprocessed waste
    finding its way into a bomb program - the concern was for foreign powers.

    The Carter Administration felt that it could not ask these other nations to
    forego waste reprocessing, if the USA still did waste reprocessing. So
    nuclear waste reprocessing / recycling was halted in the USA.

    The problem is that these other nations did NOT follow the USA's lead.
    The United Kingdom has continued reprocessing at its facilites at
    Sellafield along the Cumberland Coast ever since the USA's self-imposed
    ban. Likewise, for France; which has continued reprocessing at their
    facilities at La Hague.

    Japan has had either the UK or the French reprocess its waste - until
    fairly recently when it started its own reprocessing plant.

    So the whole reason for foregoing the advantages of reprocessing for the
    USA, was so these other powers would stop. It's been nearly 3 decades,
    and they haven't stopped. So we should just declare that this self-imposed
    ban was a failure - since it did accomplish its stated goals - and begin
    reprocessing again.

    Dr. Gregory Greenman
    Physicist
     
  10. Feb 4, 2006 #9

    Astronuc

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    Morbius,

    We have some catching up and relearning to do.

    Also, something of personal interest to you, I had a rather brief and interesting discussion about IFR recently. :wink: It may be back on the table as well. It will be interesting to see where that goes!

    Astronuc.
     
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