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Can one purchase depleted uranium?

  1. Dec 21, 2012 #1
    I'd like a small sphere of DU to illustrate mass, i.e. compare it to an equivalent (mass or radius) sphere of aluminum (say). I understand DU is used in airliners and yachts and it is safe so long as it is not aerosolized or particles are inhaled.

    Are small samples of DU available commercially?
     
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  3. Dec 21, 2012 #2

    berkeman

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    Why would DU be used in an airliner?
     
  4. Dec 21, 2012 #3
    For CG adjustments, I believe.
     
  5. Dec 21, 2012 #4

    Astronuc

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    Counterweight.
     
  6. Dec 21, 2012 #5

    SteamKing

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    In the US, DU can be possessed only by someone who holds a license to do so.
    The license is issued by the Nuclear Regulatory Commission (see this link:
    http://www.nrc.gov/reading-rm/doc-collections/cfr/part040/part040-0025.html)
    The holder is permitted to obtain DU only for certain specified purposes.
     
  7. Dec 21, 2012 #6

    AlephZero

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    I don't think it is used any more. Boeing changed to tungsten back in the 1980s.

    http://news.bbc.co.uk/1/hi/sci/tech/593649.stm

    Of course an even better idea is to design planes so the the CG is in the right place without carrying excess weight around.
     
  8. Dec 21, 2012 #7

    berkeman

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    Yeah, and it would seem much more optimal to have a lighter counterweight move over a longer length of the aircraft. Weird.
     
  9. Dec 21, 2012 #8

    Astronuc

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    There are some exemptions from licensing, if the mass is below the limit for unimportant quantities.
    http://www.nrc.gov/reading-rm/doc-collections/cfr/part040/part040-0013.html

    Best to read the entire 10 CFR 40, and either contact the NRC or Agreement State.
    http://www.nrc.gov/reading-rm/doc-collections/cfr/part040/

    One company indicates that it sells DU products.
    http://www.2spi.com/catalog/chem/depleted-uranium-products.html


    The idea of the license is to ensure proper care and disposition of the DU.


    As for Boeing counterweights: Depending on model and configuration, 21 to 31 counterweights in each tail assembly. Each aircraft has between 692 and 1059 pounds of DU.
    http://pbadupws.nrc.gov/docs/ML0321/ML032180089.pdf

    "Further, starting in 1981, customer airlines were provided
    tungsten replacement counterweights which may or may not
    have been installed in place of the original depleted uranium
    counterweights. At the worst case, the following estimate
    can be made based on the number of aircraft and spare
    depleted uranium counterweights sold. There were 550
    aircraft produced between 1968 and 1981 utilizing depleted
    uranium counterweights. With spares, there is a possible
    world distribution of 15,000 weights (about 300 tons)."
     
    Last edited: Dec 21, 2012
  10. Dec 21, 2012 #9

    Bandit127

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    A bit off topic, but Concorde had to shift fuel around to maintain the correct CoG for flight trim. Up to 33 tons of fuel was available in the trim tanks for this.
    http://www.concordesst.com/fuelsys.html
     
  11. Dec 22, 2012 #10

    AlephZero

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    These counterweights don't move around. One reason for them is that it's a very tough problem working out an accurate CG position for a structure as complex as a B747, even with today's CAD systems, and for aircraft as old as the B747, the original detail drawings wouldn't have been done with a CAD system anyway.

    So you built the first prototype, weighed it, and then "balanced" it to put the CG where the aerodynamics guys had assumed it would be. The reason for using material as dense as possible was to make the counterweights small enough to "hide" inside the aircraft nose or tail.

    For operating the aircraft with different loading conditions etc, you can fine tune the CG by moving the fuel and/or cargo around.

    In principle its a "simple" problem - just get the mass and CG positions of all the parts and add them up. The trouble starts when you try to collect ALL the data, including the "non-obvious" bits like the fasteners (nuts, bolts, rvets, wiring clips, etc), flight deck equipment etc - for example there is about a quarter of a ton of paint on a B747! All these "odds and ends" might add up to 10% of the total mass of the structure.
     
  12. Dec 22, 2012 #11

    berkeman

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    Very interesting, thanks Aleph. Yet again I learn something new here at the PF. :smile:
     
  13. Jan 12, 2013 #12
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