Friday, January 23, 2009

The Truth about DU?

We're hearing increasingly reports of the use of Depleted Uranium (DU) tipped tank shells in the Gaza conflict by the IDF. Although confirmation is still required the use of such armour piercing munitions seems very likely to me. First used by the US army in the Gulf War, they have found increasing use because of their... well, increased armour piercing capability!

And of DU there is tons and tons of it about: it's the inevitable (and otherwise rather useless) by-product of the uranium enrichment process that extracts the fissionable (and thus useful) uranium isotope U235 from natural uranium. The enriched uranium (rich in U235) is used either for civilian nuclear energy production or for the production of weapons (Hiroshima-style A-bombs). The by-product is Depleted Uranium (DU), mainly U238 and other naturally occurring uranium isotopes.

Neither Natural nor Depleted Uranium are highly radioactive, in fact so little radioactive that using small slab (of this extremely dense material) of it as, say, an office paper weight, would not expose one to dangerous levels of radiation. But slightly radioactive it is nonetheless (in fact using a piece of uranium ore as a paper weight for photographic paper lead to the discovery of radioactivity by Henri Becquerel).

But uranium is also a heavy metal and as such chemically toxic in probably more than one way (the element uranium has a rather rich chemistry).

As a chemist I've contemplated making small amounts of (Natural, not enriched) uranium metal in my backyard by magnesiothermic reduction of uranium tetrafluoride (UF4 - aka Green Salt) with magnesium powder. What holds me back (among other things) is that such a reaction would almost inevitable lead to fine airborne particles of uranium. Breathed in, even at low radioactivity (combined also with the chemical toxicity) this has to be a recipe for cancer and possibly other ailments. It's not hard to imagine what happens to the DU in DU tipped tank shells when they hit a hard object: inevitable this must lead to DU aerosols and DU dust being generated...

The teratogenicity of such aerosols is starting to be studied in great detail and a truly excellent study on this subject can be found here. Hat tip to Nevin for this find and for blogging about it.

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