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Touching weps grade uranium/plutonium

  1. May 18, 2005 #1


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    What would the timetable be for health for a person who touches with their bare hands, weapons grade nuclear material. Theres this stupid movie on and this guy was holding material for his "home made nuclear bomb" and im thinken.. come ooooon.
  2. jcsd
  3. May 18, 2005 #2


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    The pits are warm to the touch.

    I know some folks who dismantle nuclear warheads. Obviously, one tries to minimize exposure.

    It would be quite simple to take a representative mass, e.g. 10 kgs of both Pu and U, and use the decay constants to figure out the activity, and from that the dose. The activity then gives one a distributed energy source with which one can determine the heat flux. With the appropriate surface heat transfer coefficient, one can determine a reasonable approximation of the pit surface temperature.
  4. May 18, 2005 #3


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    If you are talking about handling pure Plutonium-239; there would be
    ZERO effect. Pu-239 decays by emitting a 5.245 MeV alpha particle.

    Because alpha particles have a charge of +2 [ they are doubly ionized
    helium nuclei ]; they interact very strongly with matter and lose their
    energy very quickly - hence they have a very short range. The range is
    so short, that the alpha particle will not even penetrate the dead layer
    of skin that surrounds your body. Therefore, the radiation from the
    Plutonium doesn't interact with live tissue - therefore, the health effect
    is zero.

    In fact, when Russian scientists had assembled the Plutonium core for
    "Joe I"; the first Russian nuclear test which was their copy of Trinity;
    the Russian scientists presented the core of the device to Joseph Stalin,
    and he held it in his hands and commented about it being warm to the

    It's not good practice to handle radioactive material in that manner -
    at least one should wear latex gloves. In one of her, "Behind Closed Doors"
    programs, Joan Lunden went to Los Alamos where she handled a ball of
    Plutonium while wearing latex gloves. The ball was also coated in a
    thin layer of stainless steel to protect the surface.

    If you are talking about weapons grade uranium, again the risk is zero.
    Weapons grade uranium is mostly Uranium-235, which has a half-life of
    703.8 million years! Since the radioactivity is inversely proportional
    to the half-life, and Plutonium-239 has a half-life of 24,110 years ;
    Uranium-235 is 29,191 times LESS radioactive, atom per atom; as is

    When you see movies where Plutonium and Uranium [ even weapons
    grade ] are protrayed as this stuff that glows green and will give you
    deadly radiation sickness if you get anywhere near it - then you know
    you are watching a movie by someone that is absolutely CLUELESS
    about nuclear technology and radioactive materials.

    Dr. Gregory Greenman
  5. May 18, 2005 #4


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    Morbius, I was under the impression that Pu is one of the most radiologically toxic substances on earth. Is it only if you inhale it?
  6. May 18, 2005 #5


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    The fact that the alpha particles have a high LET - Linear Energy Transfer -
    which means they lose a lot of energy per unit distance is a double-edged

    If the alpha emitter is external - it means that the alpha particles can't
    get in - they can't get through the dead layer of skin.

    However, if you ingest or inhale the alpha emitter - then you've "solved"
    the problem of getting into the body for the alpha emitter.

    The alpha particle in that case is now IN the body right next to living
    tissue. Now the fact that the alphas have a high LET means that they
    deposit their energy in a very short track - hence they do a lot of
    damage - which accounts for the high radiological toxicity.

    The dose is a measure of energy deposited per unit mass of material.
    The original unit - the rad - is 100 ergs per gram. The SI unit is the
    Gray which equals 1 Joule per kilogram = 100 rads.

    The "dose equivalent" takes into account that different forms of
    radiation have larger or lesser effects. So the dose is multiplied by
    a "Quality Factor" to give the "dose equivalent. The "Quality Factor"
    for photons [ gamma and X-rays ] is one. The Quality Factor for alphas
    is 20.

    When you multiply "rads" by a quality factor, you get a dose equivalent
    in "rems" [ rads equivalent man ]. For the SI units, when you multiply
    a dose in Grays by a Quality Factor - you get a dose equivalent in a unit
    called the Sievert.

    So, an alpha emitter like Plutonium OUTSIDE the body - is not to worry.

    An alpha emitter INSIDE the body is going to do a lot of damage.

    Courtesy of the University of Michigan:

    http://www.umich.edu/%7Eradinfo/introduction/lesson/properties.htm [Broken]


    Dr. Gregory Greenman
    Last edited by a moderator: May 2, 2017
  7. May 18, 2005 #6


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    So whats the danger in a 'dirty bomb' if touching this stuff is not so dangerous?
  8. May 18, 2005 #7


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    Theoretically a "dirty bomb" does oxidize or aeresolize it, so you can breathe it. However, the reality of the dirty-bomb threat is somewhat overblown. Most media reporting on the subject seems to operate under the all-radioactivity-is-equally-bad misconception. But composition and method of dispersion matters.

    Next question for Morbius: I know uranium is somewhat volatile - I thought Pu would just about spontaneously combust in air at room temp...?
  9. May 18, 2005 #8


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    Both uranium and plutonium are pyrophoric when finely divided, as in powder, or shavings, e.g. from a machining operation. The solid material should not be a problem unless there is a good source of oxygen.

    Regarding spontaneous combustion, IIRC Pu still needs a flame source.
  10. May 19, 2005 #9


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    You are confusing two very different concepts - and types of weapons.

    A so-called "dirty bomb"; or RDD - Radiological Dispersion Device - doesn't
    use "weapons grade" material!

    An RDD uses highly radioactive material bundled with explosives. When
    the explosive explodes, it disperses highly radioactive material - material
    that emits gamma radiation, around.

    Gamma radiation, which is electromagnetic radiation - photons - like
    X-rays, except even more powerful and energetic; will NOT stop at the skin.
    Gamma radiation is highly penetrating.

    So a "dirty bomb" disperses this highly radioactive material around - so
    that it maximizes the number of people that are exposed to it.

    Weapons grade material, on the other hand, like Uranium and Plutonium
    is not very radioactive at all - only very slightly - and as I've stated, the
    type of radioactivity from Uranium and Plutonium is very easily shielded;
    a piece of paper, or the dead layer of skin on your body will do.

    Although Uranium and Plutonium are not very radioactive, they are
    "fissile" - that is they readily undergo the nuclear fission reaction. If one
    arranges a device such that one can, on command, assemble this weapons
    grade material into a "prompt supercritical" configuration - and add a
    neutron source - the result will be a rapidly growing uncontrolled chain
    reaction of nuclear fission - thus releasing tremendous amounts of
    energy. Such a device is a nuclear weapon.

    So you have two VERY DIFFERENT animals here. Weapons grade material
    can be made into a nuclear weapon - but it is pretty useless for the
    "dirty bomb" that you are talking about.

    Dr. Gregory Greenman
  11. May 19, 2005 #10


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    Yes - Plutonium is "pyrophoric" - that is it can spontaneously combust in
    air at room temp. It does that if you have a fine powder - with lots of
    surface area per unit volume. Therefore, when the surface oxidizes - and
    releases heat - you can start combustion. It's not really "spontaneous" -
    you need a triggering event - but something like the heat of friction,
    should the powder become "sandwhiched" between two moving surfaces -
    will trigger the combustion.

    However, if you have a big ball of Plutonium - the surface will oxidize -
    but the whole ball isn't going to catch fire.

    Think of ordinary baking flour. You aren't concerned that the baking
    flour sitting in the canister in your kitchen is suddenly going to explode.

    However, a fine "mist" of airborne flour is very explosive - and you used
    to hear a lot about grain elevators in the Midwest where flour was
    stored in large quantities exploding. Here it was the flour "mist" that
    was spontaneously combusting.

    Dr. Gregory Greenman
    Last edited: May 19, 2005
  12. May 19, 2005 #11


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    I understand the different types of weapons but what I wasnt understanding is how i assumed you just had unrefined uranium in a dirty bomb... and its deadly as hell... but when its refined (which to my mind brings up 'concentrated' deadliness or what not), how is it all of a sudden not so deadly. Well actually no i dont understand now. What materials are used in hypothetical dirty bombs if not the same unprocessed uranium that eventually winds up as refined nuclear weapons material?
  13. May 19, 2005 #12


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    First - uranium isn't "deadly as hell" - either in refined nor unrefined form.

    I assume you understand that the radioactivity of an isotope is
    INVERSELY proportional to the half-life - that is the shorter the half-life,
    the more radioactive the isotope is, and consequentially, the longer
    the half-life, the less radioactive an isotope is.

    Natural uranium, fresh from the ground, is 99.3% U-238 and 0.7% U-235.

    The U-238 [ which is what "depleted uranium" is made of ] has a half-life
    of 4.5 BILLION years - so it is only very slightly radioactive. With such
    a long half-life, it's almost stable.

    The U-235 has a half-life of 704 MILLION years. While U-235 is a little
    over 6 times more radioactive than U-238; it is still only slightly

    Weapons grade uranium is mostly U-235. So while about 6X more active
    than natural or depleted uranium; it is still very low.

    So in terms of radioactivity; depleted uranium has the least, natural
    uranium somewhat more than depleted; and weapons grade 6X the other
    two - but still very low.

    Additionally, as before, uranium is an alpha emitter. Alpha radiation
    will not penetrate a sheet of paper, nor the dead layer of skin.

    You don't use uranium in an RDD or "dirty bomb". The types of materials
    that one would use in an RDD should be relatively short lived gamma
    emitters. Cobalt-60 and Cesium-137 would be good candidates.

    There is so much really BAD information in the media. The media
    reporters don't understand this stuff - and haven't made an effort to
    understand it - because it's really very simple.

    In the media, a "nuke" is a "nuke" is a "nuke". They don't draw a distinction
    between RDDs and a real nuclear weapon. That's why there are a lot of
    people that think that "weapons grade" uranium goes into a "dirty bomb".

    After all, a "dirty bomb" is a weapon - so you use "weapons grade". WRONG!!!

    An RDD or "dirty bomb" has virtually nothing in common with a real
    nuclear weapon. A dirty bomb doesn't use "weapons grade" uranium.
    It also doesn't make a big explosion that can level a city - only a real
    nuclear weapon does that.

    A "dirty bomb" is a very, very, simple device relative to a real nuclear

    Dr. Gregory Greenman
    Last edited: May 19, 2005
  14. May 19, 2005 #13
    in that movie about first US nucluar bomb, one of the scientist died from touching two sphers of weapon grade uranium. you know what i'm talking about ?
  15. May 19, 2005 #14


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    Not quite.

    What you are most likely referring to is the case of Louis Slotin.

    The part of the movie "Fat Man and Little Boy", in which the character
    played by John Cussack receives a fatal radiation dose is a piece of
    fiction that did not occur during the Manhattan Project - but is modeled
    after an accident at Los Alamos that occurred 2 years later.

    Louis Slotin was a scientist at Los Alamos, and in 1947 he was doing an
    experiment at Los Alamos checking the critical mass for a bomb core in
    what they called "tickling the dragon's tail".

    He had 2 hemispheres of uranium - that if assembled would give you a
    critical mass. He was supposed to get them almost, but not quite
    assembled by holding them apart with a screwdriver.

    Unfortunately, the screwdriver slipped - and the 2 hemispheres
    assembled in a critical mass - there was a nuclear chain reaction -
    and Slotin died several days later from massive radiation.

    But this is NOT radioactive decay of the uranium. He accidently
    assembled a bomb core. It was a fission chain reaction - like what
    happens in a nuclear bomb when it's detonated that produced the
    massive radiation. Louis Slotin, in essence, set off a small nuclear
    "explosion" - and he died from the radiation.

    Dr. Gregory Greenman
    Last edited: May 19, 2005
  16. May 19, 2005 #15
    thanks for claryfing, one question : would there be a regular nuclur explosion with mushroom and stuff ( like hiroshima ) from that accident ?
  17. May 19, 2005 #16


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    So whats all the fuss with people saying "terrorists will steal nuclear material and set off dirty bombs!!!"? I mean if this is such basic information, why is it never disputed out in the media?
  18. May 19, 2005 #17

    Uranium-235 and plutononium-239 are fissile radioisotopes — and therefore they can be used to make fission weapons — but they do not happen to be very radioactive. If you were making a dirty bomb, you might want to use radioisotopes that are much more radioactive — such as cesium-137, strontium-90, etc. You can find those radioisotopes in nuclear waste.

    So, we are worried about terrorists stealing:

    1. weapons grade plutonium or uranium, in order to make fission weapons (atomic bombs that produce a large blast like the ones dropped Hiroshima or Nagasaki)

    2. nuclear waste, in order to make dirty bombs (rudimentary devices composed of ordinary chemical explosives surrounded by highly-radioactive isotopes intended to be dispersed by the chemical explosives in populated areas in order to poison people and create terror)
    Last edited: May 19, 2005
  19. May 19, 2005 #18


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    So, what, you steal nuclear waste and extract the highly radioactive components?

    What kind of material is used at nuclear power plants then and how do they produce nuclear waste (and what is the nuclear waste cmposed of in general). Also, whats the dangers associated with the Yucca mountain thing. Im getting from you guys that nuclear waste is highly radioactive... and then say its inversely proportional which means its half life would be relatively short.. but people complain that we're dealing with materials that'll be radioactive for tens of thosuands of years. Or is 10,000 years considered very short time when it comes to radioactivity...
    Last edited: May 19, 2005
  20. May 20, 2005 #19
    Fission products and how they are produced

    I think isotope separation would be comparatively difficult for what is supposed to be a relatively simple-to-make device. I suppose one might grind the pellets up into a powder before emplacement into the dirty bomb. That might be difficult as well, though, since working with the waste directly instead of remotely is radiologically hazardous.

    Garwin writes about this subject, so perhaps you can find what you are looking for on his Federation of American Scientists (FAS) site:

    In light water reactors — the type used in the United States for electrical power production — the fuel is low-enriched uranium. This is uranium that has been enriched in the fissile isotope U-235 from its natural representation level of 0.7204% to a representation level of 2.5-3.5%. Most of rest of the uranium is U-238 (a non-fissile isotope).

    MOX can also be used. This is a mixture of uranium and recycled or reused plutonium.

    The U-235 is fissioned and in doing so produces fission products. The fission products are considered waste, since they themselves cannot be fissioned (some of them would be useful in medicine and industrial activities, however). Here is a graph of the different fission products produced and their relative proportions:

    (I also attached this graph at the end of this post.)
    Notice how the graph is bimodal — i.e., it has two peaks. One peak is around atomic mass number 95 and the other peak is around atomic mass number 140.

    Another type of waste produced is comprised of so-called transuranics. These are produced starting when Uranium-238 captures a neutron which subsequently decays to a proton. Since elements are defined by the number of protons their atoms have, as you can see this produces an element that is higher than — or trans — Uranium. The process continues for a ways beyond uranium, and we get an assortment of elements — that were not in the fresh, unburned fuel — including Plutonium, Neptunium, Curium, and Americium.

    Mostly, the spent fuel is still U-238 (which by itself has very low radioactivity and presents very little radiological danger), just as it was before it was burned in the reactor. There is less U-235 than the fuel started out with, since much of it was burned (fissioned), and the rest (~1% by weight?) is composed of the radiohazardous products I just mentioned.

    Some party might steal the waste and make dirty bombs out of it. Some party might steal the waste and extract the Plutonium therein to use to make fission bombs. The waste might leak into the environment through groundwater. The waste might be purged from the repository by a volcanic eruption. The waste might be purged from the repository by a meteor impact. The waste might be purged from the repository by terrorists blowing the repository up.

    Some of its halflife would be short. The waste is composed of multiple isotopes, which in turn procuce other isotopes as they decay, and so on. This procuces a complex decay graph over time of total radioactive flux produced by the waste. It does not produce a simple logarithmic curve. See Garwin and Charpak:

    I cannot speak for them. Bernard Cohen points out...

    ...that some stable isotopes (such as those of lead, selenium, etc.) are poisonous, too — and they last forever, instead of decaying from more-poisonous to less-poisonous as nuclear waste does.

    Every practical-sized clump of radioisotopes is radioactive — for what I would conceive to be practical purposes — forever. The radioactivity does not end until the last radioisotope decays to a stable isotope. Analogy: would the Earth's gravity turn off when you eventually travel far enough away, or would it just keep getting dimmer and dimmer as the space between you and the Earth grew?

    Attached Files:

    Last edited by a moderator: Apr 21, 2017
  21. May 20, 2005 #20


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    What you are dealing with are a bunch of people that are very adept at
    lying - and a media that is uncritical.

    If you reprocess nuclear waste and recycle actinides like Plutonium
    back to the reactor as fuel - then the longest lived nuclear waste
    component is Cesium-137 which has a half-life of 30 years - not the
    10s of thousands of years. The parts of the nuclear waste that have
    the long half-lives, like Plutonium are NOT very radioactive - and can
    be used as fuel - so we don't have to keep them around.

    There's nothing contradictory here if you think about it. It's just as I
    stated above, the radioactivity is INVERSELY proportional to the
    half-life. The long lived radioisotopes have very low levels of radiation,
    and are easily shielded. The intensely radioactive isotopes don't live
    very long - they have short half-lives.

    The problem is that unthinking people lump the two together - so they
    think they have long-lived intensely radioactive waste - and that is just
    plain NOT TRUE!!! Be mindful of that next time you hear your local
    anti-nuclear fanatic speak.

    The input fuel for nuclear power plants is slightly enriched uranium -
    only slightly radioactive - because it came out of the ground that way.
    In the reactor, some of the uranium is fissioned. The result of fission
    are the "fission fragments" which are the true waste - radioisotopes
    such as Cesium-137, Strontium-90, Iodine-131..

    These are the intensely radioactive materials - Cesium-137 has a half-
    life of 30 years, Strontium-90 has a half-life of 29 years, and Iodine-131
    has a half-life of 8 days. But they disappear at a fast rate.

    Sometimes the uranium doesn't fission, but absorbs a neutron - and
    the atom is transmuted into something else. This is where you get the
    Plutonium and other actinides. Plutonium-239 has a half-life of
    24,000 years. The other actinides have similarly long half-lives.

    However, what you want to do with the Plutonium and other actinides
    is to remove them from the waste - and put them back into the reactor
    as fuel. On this second go-round, they will fission and become fission
    products like Cs-137, Sr-90, and I-131.

    So there's no reason to have long-lived radioisotopes in the waste.

    One often hears that we have 77,000 metric tonnes of nuclear waste.
    That's true - that's how much nuclear waste has accumulated in the
    nearly one-half century of the use of nuclear power. That's the TOTAL
    accumulation. But people imagine that 77,000 tonnes is a mountain.
    Actually, the volume of nuclear waste is about the volume of a high
    school gymnasium. As hittsquad points out - the vast majority of
    this volume is Uranium-238; about 94% of it. This U-238, with a half
    life of 4.5 BILLION years is only slightly radioactive - no more so than
    when it came out of the ground. If we reprocessed the nuclear waste
    to remove the relatively benign U-238; then the amount of nuclear
    waste drops by about a factor of 20.

    This is what other countries do when they reprocess their nuclear waste.
    Great Britain's Nuclear Fuels Ltd has a plant at Sellafield to reprocess.
    France has their facilities at La Hague. Unfortunately, the USA does
    not reprocess - because the anti-nukes got Congress to pass a law in
    1978 to forbid it.

    You have to hand it to the anti-nukes; they get Congress to pass a law
    to outlaw the solution to the problem - thus guaranteeing that they have
    something to complain about. Good tactic - although disengenuous.

    As far as Yucca Mountain - it has been VERY, VERY thoroughly studied
    by scientists at LLNL, for example:


    LLNL scientists recommended proceeding with Yucca Mountain years
    ago. The concept of geological disposal has been endorsed by our best
    scientists - the National Academy of Science and Engineering. In fact,
    it was the National Academy of Sciences that first suggested geological
    disposal back in the late '50s.

    Unfortunately, Yucca Mountain has turned into a political football -
    with lots of people telling lies to scare you - and the media doesn't
    check it out. For example, they tell you that there will be accidents
    in the transportation of the waste. However, the waste is shipped in
    casks that are indestructible with respect to transportation accidents.

    Sandia National Labs has tested the casks extensively - parking the
    cask-laden truck on a railroad track, putting rockets on a locomotive
    and slamming it into the casks at speeds exceeding anything a real
    train could do:

    http://www.sandia.gov/recordsmgmt/ctb1.html [Broken]

    See the video at:

    http://www.nei.org/doc.asp?catnum=2&catid=83 [Broken]

    They also set the casks in vats of burning jet fuel:


    Sandia is one of the Labs that manage our nuclear weapons. The reason
    Sandia was chosen to conduct the tests on the fuel casks is that they
    do the tests on the casks that are used to ship nuclear weapons around.
    If the casks is safe enough to ship something like a nuclear weapon
    around - it surely is safe enough to ship a small quantity of nucear waste.

    Dr. Gregory Greenman
    Last edited by a moderator: May 2, 2017
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