Natural uranium will not normally fission and so cannot be used in weapons or as a reactor fuel. The exception is in heavy water reactors. To make it fissile the proportion of the fissile isotope, U235 must be increased, resulting in enriched uranium. the remaining material is depleted in U235, hence depleted uranium. Depleted uranium is less radioactive than either enriched or natural uranium. Several uses for what would otherwise be a waste product have been found.
The high density and low cost of depleted uranium makes it a useful ballast used in aircraft. Many commercial as well as military aircraft apparently have blocks of depleted uranium to maintain trim.
The high density and comparatively high tensile strength of uranium, plus its incendiary properties when heated make it an attractive material for high velocity penetrators. These include tank guns (such as the German - used by the US - and French 120 mm smoothbore, the British 105 and 120 mm rifles, and the Russian 125 mm smoothbore, the 30 mm cannon used by US A10 ground attack aircraft, and shipborne antimissile systems such as the US 20 mm Phalanx. The alternative to depleted uranium in such projectiles in tungsten carbide, also widely used. Depleted uranium is widely used by the US and it allies and also by Russia. It was used in the Gulf War, in the western intervention in the former Yugoslavia,
and on the target ranges of many countries.
Furthermore, the high density and strength also mean that it can be used as armour. There is a version of the US M1 tank that incorporates layers of deleted uranium into its composite armour.
I am no expert, but radioactivity is probably not a major risk with depleted uranium. In the long term, as an alpha emitter, there minor a risk from small particles lodged in the body especially the lungs. But this would probably require decades of exposure. The toxic effects of uranium are more serious, uranium is a heavy metal. But whether it is more or less toxic than lead (also widely used on the battlefield!), I do not know.
I maybe cynical, but I suspect the long term risks of post war exposure to depleted uranium is much less than the risks of having it shot at you. Nobody has expressed concerns over the thousands of tonnes of lead scattered about the world's battlefields. But people are rarely rational where uranium is concerned!
Jon
Charles Carrigan wrote:
> Burgy,
>
> There are three isotopes of U (238, 235, 234), all are radioactive and decay to daughter isotopes. 238U is a long lived radioactive isotope, and decays through quite a long daughter sequence and eventually ends up as stable 206Pb. The half life is ~4.5 billion years, essentially the age of the earth. It makes up ~99% of all U, because the half-lives of 235 and 234 are much shorter. 234U is actually produced in the decay of 238U as one of the daughters in the decay series.
> Other products can be produced I believe in reactors, though I'm unfamiliar with the process.
>
> I have no understanding of what "Depleted Uranium" would be. Depleted in what? "Concentrated Uranium" sounds more like what is described.
>
> Bullets made of U would certainly pose health hazards if the material were placed into your body through food contamination, bullets, inhalation, dust on your skin, etc. The radioactive decay produces gamma rays, alpha particles (He nuclei), which can cause damage to cells and to DNA, not to mention the Pb daughter product, dangerous to organisms in its own regard as a heavy metal. These kinds of things should be classified as chemical warfare if they aren't already. I find it quite disturbing that these things would be used in warfare, and the claim that the US has used these things within the US is disturbing enough to be difficult to believe. I'd like to find out if the story has any credibility.
>
> Yours,
> Charles
>
> At 01:15 PM 2/23/01 -0700, you wrote:
>
> > I was at a meeting yesterday where the subject was the US sanctions on
> > Iraq (the speaker, of course, was against them). Much of what he had to
> > say made a lot of sense; some did not.
> >
> > In a leaflet he distributed and talked about was a description of what
> > was called "Depleted Uranium," (DU), which was also identified as the
> > isotope U-238. Included were all sorts of claims about it, claims which I
> > do not see as credible. But my physics career is too far remote now in
> > time for me to fairly judge these claims; perhaps someone here might
> > comment on them.
> >
> > These are the claims, as extracted from somewhat more volitile phrases in
> > the leaflet:
> >
> > 1. The US used DU munitions in Iraq, Kuwait, Kosovo, Serbia, Bosnia,
> > Puerto Rico, Okinawa and within the US.
> >
> > 2. Thousands of individuals have been exposed (to what?) ...
> >
> > 3. DU is a health hazard if inhaled, ingested, or gets in wounds.
> >
> > 4. Respiratory and skin protection must be worn by everyone within 80
> > feet of DU contaminated equipment.
> >
> > 5. DU contamination makes water & food unusable.
> >
> > 6. DU is made from the non-fissionable byproduct of the uranium
> > enrichment process.
> >
> > 7. DU is used in munitions, shielding and commercial concrete.
> >
> > 8. DU munitions are solid U-238 (several examples given).
> >
> > 9. Upon impact, radioactive and heavy metal poison U-238 fragments &
> > oxides are created.
> >
> > 10. Reported health effects (official DOD document, not identified)
> > include (long list of diseases).
> >
> > 11. Doing nothing wall leave "thousands of radioactive heavy metal poison
> > bullets" around.
> >
> > The article is written by a Doug Rome, Ph.D., who is identified as a
> > former ODS (?) health physicist and a former Army DU Project director.
> >
> > If U-238 is a stable isotope, as I always thought it was, then whence
> > comes the radioactivity? And while I'm fairly sure that ground up U-238
> > powder is probably not good to inhale, is it really a poison? That is, is
> > it worse than, for instance, an equal amount of West Texas dust?
> >
> > The anti-sanctions movement seems to me to be a good one to support. But
> > these claims, which seem wild to me, don't give me any confidence in the
> > rest of their message.
> >
> > Comments appreciated.
> >
> > Burgy (John Burgeson)
> >
> > www.burgy.50megs.com
>
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