Uranium Depletion Weapons
█ LARRY GILMAN
Depleted uranium (DU) munitions are armor-piercing or general-purpose ammunition rounds that are composed, in part, of depleted uranium. Depleted uranium is uranium that has had most of its 234 U and 235 U removed for use in nuclear power or nuclear weapons, leaving metal that is almost entirely 238 U. 238 U is the least radioactive isotope of uranium, with a half-life of 4.46 billion years (6.3 times that of 235 U). It is used in munitions because of its density and hardness. The high density of DU (1.68 times that of lead, 2.43 times that of steel) allows it to transfer more kinetic energy to a target for a given round size than any other practically available metal. This, combined with its hardness, enables it to penetrate armor much more effectively than armor-piercing rounds made of other metals (e.g., tungsten). A typical armor-piercing DU round consists of a long, pointed shaft of DU that is surrounded by a sabot (from the French for "shoe"; a casing that fits the bore of the gun). When the round is fired, the sabot falls away, transferring some of its kinetic energy to the DU shaft. When the shaft strikes end-on, its long, narrow shape concentrates all of the round's kinetic energy on a small area; as the round penetrates the armor it also tends, thanks to the particular mechanical properties of metallic uranium, to sharpen rather than to blunt or mushroom, further increasing its penetrating power.
DU is used not only for ammunition, but for ballast, gyroscope rotors, balancing weights on aircraft, armor enhancement, and in other applications calling for high-density material. The armor of the United States M1A1 Abrams Main Battle Tank, for example, consists of a layer of DU sandwiched between two layers of steel.
A variety of DU munitions have are in use by at least 20 technologically advanced military organizations around the world. The U.S. military leads both in quantities deployed and quantities used in combat. DU munitions were used by several branches of the U.S. military both in the Gulf War of 1991, in Bosnia-Herzegovina in 1994–95, and in Kosovo in 1999. During the Gulf War, U.S. forces fired 320 tons (290,300 kg) of DU munitions; during in Bosnia-Herzegovina, 3 tons (2721 kg); and in Kosovo, 10.2 tons (9253 kg). Much of this material remains on the ground.
There is no controversy about the military effectiveness of DU munitions. In an incident during the Gulf War, a U.S. Abrams tank with DU-enhanced armor was struck three times by main-gun rounds from three attacking Iraqi T-72 tanks. The Abrams remained operative despite the hits and responded with three DU main-gun rounds, destroying all three Iraqi tanks. Nevertheless, international debate has centered on the question of whether DU munitions pose a health hazard to military forces exposed to them during use or to civilian populations inhabiting regions contaminated by DU. There are two possible sources of health damage from DU: chemical toxicity and radioactivity.
Chemical toxicity. When a DU round strikes armor, it is pulverized and raised to a high temperature. Several oxygen-uranium compounds (uranium oxides) form under these conditions and can be harmful if inhaled or otherwise ingested (e.g., by direct penetration of the skin). Ingestion of sufficiently large quantities of uranium oxides can be harmful, especially to the kidneys. However, the U.S. government states that the quantities of uranium oxide that can be plausibly ingested under combat conditions, or by residents of contaminated areas, cannot be great enough to cause measurable health effects.
Radioactivity. The radioactivity of 238 U is very low compared to that of 235 U; further, although DU contains trace quantities of elements that are more radioactive, such as 235 U, americium, neptunium, plutonium, and technitium, these impurities increase DU's radioactivity by only about 0.8% over that of pure 238 U. Most scientists agree that the DU radiation hazard to troops and civilian populations in contaminated areas is too low to measure. Nevertheless, anecdotal reports of increased leukemia rates and other health problems in veterans exposed to DU have caused enough concern to trigger investigations of DU health effects by the United Nations Environmental Programme and several governments.
Although no ill effects from DU exposure have yet been definitely established by any study, the U.S. Department of Veterans Affairs is now tracking the health of veterans exposed to DU. Furthermore, the International Committee of the Red Cross has urged all countries that use DU munitions to review whether they comply with international agreements that forbid "weapons, means, or methods of warfare of a nature to cause superfluous injury or unnecessary suffering, which have indiscriminate effects, or which cause widespread, long-term and severe damage to the natural environment." Several such studies are now being pursued by European governments and by the U.S. government.
█ FURTHER READING:
Department of Defense Deployment Health Support Directorate. "Depleted Uranium Information Page." 2001. < http://www.deploymentlink.osd.mil/du_library/ > (March 6, 2003).
International Committee of the Red Cross. "Depleted Uranium Munitions." June 6, 2001. < http://www.icrc.org/Web/eng/siteeng0.nsf/htmlall/57JR5D?OpenDocument > (March 6, 2003).