RE: Request for Info on DU Munitions: Useful(?) Information

["Tim Gillespie" <tgillespie@sec-tn.com>]

In light of all of the banter about DU, I felt compelled to provide some
widely accepted useful information. The vast majority is taken from
DOE-STD-1136-2000:

Depleted Uranium is typically defined as >99.8% U-238 and <0.2% U-235. At
this level of depletion, approximately 70% of the total (alpha) activity is
from U-238, while approximately 30% is from U-234. The contribution from
U-235 is negligible.

Daughter ingrowth of Th-234/Pa-234m reaches complete secular equilibrium in
approximately 1000 days, but equilibrium is effectively reached in about 100
days. As a result, there will be significant beta activity due to the
equilibrium activity of the Pa-234m 2.28 MeV beta, thereby making detection
with GM instruments simple.

DU shell by-product is almost certainly a high-fired oxide and as such, is
solubility class "Y". (my opinion).

For class "Y" Uranium, chemotoxicity is the limiting toxicity below 0.82%
enrichment. Therefore, chemotoxicity prevails for DU.

The 1999 ACGIH TLV-TWA for uranium is 0.2 mg/m^3, the TLV-STEL is 0.6
mg/m^3. For comparison, the TVL-TWA for lead is 0.05 mg/m^3 and the TLV-STEL
is 0.45 mg/m^3.

Radiologically, the target organ is the lungs, followed by the bone surfaces
(not the kidneys).

A back-of-the-envelope calculation, based on a resuspension factor of
1E-06/m, the TLV of 0.2mg/m^3 equates to a surface contamination level of
2E+05 mg/m^2, or 20 g/m^2. The actual resuspension factor is more likely on
the order of 1E-07 or 1E-08 (my opinion) based on some studies done in
Chernobyl. This would equate to surface contamination levels more on the
order of 200 - 2000 g/m^2 to produce a concentration approaching the
TLV-TWA.


My opinions only...



> -----Original Message-----
> From: radsafe@romulus.ehs.uiuc.edu
> [mailto:radsafe@romulus.ehs.uiuc.edu]On Behalf Of Franz Schoenhofer
> Sent: Friday, January 12, 2001 7:08 PM
> To: Multiple recipients of list
> Subject: Re: Request for Info on DU Munitions
>
>
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> -----Ursprüngliche Nachricht-----
> Von: Bob and/or Kathleen <kmca@mediaone.net>
> An: Multiple recipients of list <radsafe@romulus.ehs.uiuc.edu>
> Datum: Donnerstag, 11. Jänner 2001 01:51
> Betreff: Request for Info on DU Munitions
>
>
> >Dear Radsafers,
> >
> >Regarding discussions on DU munitions, and whether they may cause health
> >effects to individuals, I was wondering if someone on this list could
> please
> >direct me to research and/or investigations performed to determine the
> >byproduct constituents from burning/heat vaporizing DU similar
> to that used
> >in munitions tips, and protocols used to determine if these
> byproducts are
> >more or less biologically active than the DU solids themselves.
>
> I am far from being a specialist in uranium, but my background is
> radiochemistry, so I hope I can give you some information in
> answer to your
> questions. Do not expect some special investigations and
> research, I rather
> want to point towards common sense and some facts related to chemistry.
>
> (Depleted) Uranium is used in munition because of its extremely
> high density
> and therefore its penetrating power. It is used in metallic form.
> On impact
> the kinetic energy is partially transformed into thermal energy, which
> causes the uranium - which is anyway pyrophoric, which means that
> it easily
> reacts with the oxygen from air - to ignite. Uranium is therefore
> (partially) oxidized to uranium oxide, which deposits as an extremely fine
> powder. Uranium oxide(s) are not soluble in water. When such
> small particles
> are inhaled after resuspension, they can deposit in the lung. The lung
> fluids may dissolve extremely slowly the uranium oxide particles
> and uranium
> is carried away in the body fluids. Part of it will be excreted,
> part of it
> will be deposited in different organs of the body, the critical
> organ being
> the kidney, as it is for other heavy metals. The health impact of
> uranium in
> this case will be only related to its chemical toxicity
> which is by far higher than the radiotoxicity.
> In case that such particles would be ingested and not inhaled,
> the particles
> will pass the body without being dissolved and without having any
> impact on
> health.
>
> I can conclude that the formation of uranium oxide will by far reduce any
> possible health impact, because of the decrease in uptake.
>
> Rests of uranium not being oxidized on impact exhibit very low
> radioactivity
> and a negligible dose to people living in the vicinity, which includes
> children playing close to it. You should note, that natural background
> radiation might differ by almost orders of magnitude, depending on the
> geological conditions of an area (for instance high uranium concentrations
> in the underlying ground) and the elevation which determines the
> contribution of cosmis rays. The use of x-ray and nuclear medicine
> diagnostics will give the patient doses higher by several orders of
> magnitude - and this is socially accepted. A manyfold increase of dose
> during flight is as well accepted.
>
>
> Maybe there
> >is no relationship, but in considering all of the attention the topic is
> >receiving, I couldn't help musing that some materials have very different
> >chemical/biological effects based upon their physical manipulation.
>
> Yes, this is correct, but the transition from elemental uranium to uranium
> oxide lowers the effects.
>
>
>  I
> >confess that this may be totally inapplicable, and probably
> falls into the
> >category of comparing apples with oranges, but an example that
> came to mind
> >is plastics that are essentially biologically inert, or very
> >chemically/biologically different, when ingested or inhaled as whole,
> small,
> >or even very finely divided dust particles, but with adequate
> heat applied,
> >can disassociate into toxins (e.g., cyanides)
>
> I do not know any plastic, which would yield cyanides (which
> ones?) on being
> heated. As mentioned above, the transformation of metallic uranium to
> uranium oxides actually decreases the toxicity - which is anyway
> not because
> of radioactivity but because of the chemotoxicity.
>
>
> I would
> >appreciate becoming familiar with the research performed on the
> byproducts
> >of burning/heat vaporized DU compounds used by the NATO forces, if for no
> >other reason to confirm to friends and family outside the radiation
> >protection community that they have been performed.
>
> I am sorry that I cannot spend days to collect literature citations and
> reports just to satisfy your wish to become familiar with the research. If
> you are really interested in the topic, you can perform your own searches,
> you may follow the links which have been cited extensively on
> RADSAFE during
> the last week or so, you can search the RADSAFE archives - the topic has
> been dealt with several times during the last years - and you can perform
> internet searches on web sites of organisations involved in this
> topic. What
> I would really recommend to discard are the "informations" provided with
> mass media. Finally you could trust what I have written above, based on
> several decades of work in radiation protection and radiochemistry and on
> common sense.
>
> With my best regards
> Franz
>
>
>
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