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UNEP Balkans Report of March 2001Appendix IV(pages 116 - 118)Military use of DUIV.1 Types of military useDepleted uranium has multiple uses by military forces. As in the civilian sector it can serve as counter-ballast, in both aircraft and missiles. It is important to note that not all counter-ballasts are made of depleted uranium. Because of its density (19.0 g/cm 3 ) and resistance to penetration by anti-armour munitions, depleted uranium can be used in the armour of tanks. It is also important to note that note all tanks have depleted uranium armour. Depleted uranium has special properties that make it ideal as anti-armour ammunition; when depleted uranium rounds hits armour plating, the rods begin to self-sharpen, thereby enhancing their ability to pierce the armour. During this self-sharpening, the depleted uranium forms an aerosol, creating fine DU particles that may be inhaled.The amount of depleted uranium that forms as an aerosol will depend upon the ammunition, the nature of the impact and the type of target, whether it is an armoured vehicle or not. Both tanks and aircraft can fire depleted uranium munitions, with tanks firing larger calibre rounds (100 and 120 mm) and the aircraft firing smaller calibre rounds (25 and 30 mm). Many of the world’s armies possess or are thought to possess DU weapons (Rand, 1999). Depleted uranium weapons are regarded as conventional weapons and have been used in Depleted uranium weapons are regarded as conventional weapons and have been used in warfare. This type of ammunition is readily available on the open market. Ammunition containing DU is known to have been used in Iraq during the Gulf War in 1991, in Bosnia-Herzegovina in 1995, and in Kosovo in 1999. In addition, sites in southern Serbia and Montenegro were also hit by ammunition containing depleted uranium during the Kosovo conflict. During the Kosovo conflict, NATO aircraft used DU weapons. NATO confirmed that over 30,000 rounds of DU had been used in Kosovo (UNEP, 2000). The effectiveness of DU in kinetic energy penetrators (the rods of solid metal) has been demonstrated at various test ranges and in actual military conflicts. Kinetic energy penetrators do not explode but if they hit a hard target they may form an aerosol of fine particles. Since uranium metal is pyrophoric, the DU particles ignite and burn, forming particles of uranium oxides due to the extreme temperatures generated on impact. Most of the contamination remains inside a vehicle that has been struck and penetrated. However, some of the dust will be dispersed out into the environment and contaminate the air and the ground. Most of the penetrators that hit non-armoured targets will pass right through the target and, in most cases, remain intact. A penetrator that hits the ground will continue intact down into the soil. The depth depends on the angle of the round, the speed of the tank or plane, and the type of soil. In clay, penetrators used by the A-10 attack aircraft are reported to reach more than two meters depth. Penetrators hitting hard objects, e.g. stones, may ricochet and may be found lying on the ground meters from the attacked target. The DU dust formed during the penetration of armoured vehicles can be dispersed out into the environment and contaminate the air and the ground. It is important to note that hits by depleted uranium on "soft" targets, e.g., non-armoured vehicles, do not generate significant contamination of dust. Most contamination from depleted uranium hits on armoured vehicles should be limited to within about 100 meters of the target (CHPPM, 2000). Because 1.5 years have elapsed since the Kosovo conflict, the major interest of the UNEP mission was to examine the possible risks of remaining contamination of ground, water and biota near the impact site. The type of DU ammunition that the A-10 Warthog aircrafts uses has a conical DU penetrator. Its length is 95 mm and the diameter at the base 16 mm. The weight of the penetrators is approximately 300 grammes. The penetrator is fixed in a "jacket" (also called "casing"). The aluminium casing has a diameter of 30 mm and a length of 60 mm. The jacket fits the size of the barrel of the A-10’s gattling gun and assists the round in flying straight. When the penetrator hits a hard object, e.g. the side of a vehicle, the penetrator continues through the metal sheet, but the jacket usually does not penetrate. The A-10 aircraft is equipped with one gattling gun. This gun can fire 3,900 rounds per minute. A typical burst of fire occurs for 2 to 3 seconds and involves 120 to 195 rounds. The shots will hit the ground in a straight line and depending on the angle of the approach, the shots will hit the ground 1-3 m apart and occupy an area of about 500 m 2 . The number of penetrators hitting a target depends upon the type of target. Normally, not more than 10% of the penetrators hit the target (CHPPM, 2000). There are two sources of information on how many of the rounds fired in Kosovo by the A-10 were depleted uranium. According to the NATO information given to UN in a letter dated 20 July 2000, the mix of 30 mm rounds was approximately 5 DU rounds for every 1 ATI (tracer ammunition) round. According to NATO/KFOR information provided to UNMIK the mix was 5 DU rounds per 8 fired (KFOR, 2000). The numbers of DU rounds used in one target area range from 30 to 2320. UNEP has no information that depleted uranium was used in the cruise missiles fired by NATO forces, or that depleted uranium tank ammunition was ever fired. Nor is there any indication that depleted uranium was used by Serbian forces. IV.2 Potential health and environmental impactsNormally 10-35% (and a maximum of 70%) of the bullet becomes an aerosol on impact, or when the DU dust catches fire (Rand, 1999). Most of the dust particles are smaller than 5µm in size, and spread according to wind direction. DU dust is black and a target that has been hit by DU ammunition can be recognized by the black dust cover in and around the target (U.S. AEPI, 1994).After an attack where DU ammunition has been used, DU will be deposited on the ground and other surfaces as DU metal in pieces, fine fragments and dust, and if the DU has caught fire, as dust of uranium oxides. Around the targets in the Nellis Air Force Range, which have been used as training targets for a long period, most of the DU dust is reported to have been deposited within a distance of 100 m of the target (NELLIS, 1997). Most of the penetrators that impact on soft ground (e.g. sand or clay) will probably penetrate intact more than 50 cm into the ground and remain there for a long time. Penetrators that hit armoured vehicles form an aerosol upon impact or ricochet. Bigger fragments and pieces of DU will remain intact on the ground surface. The fine fragments and dust gradually will be transported down into the upper soil layer by water, insects and worms. Wind, rainwater or water that flows on the ground may also redistribute the fine DU dust. A part of the fine dust particles will adsorb onto soil particles, mainly on clay particles and organic matter, and thus be less mobile. Due to the different chemical properties of different soils and rocks, the effects of DU on the environment varies. Penetrators that hit clay will remain unaffected and will not affect the surrounding soil and groundwater. If they impact on quartz sand they will weather relatively fast and may contaminate the ground water. If the impact is in residual soils, penetrators and DU dust will weather more or less easily, depending on the type of bedrock. If the soil consists of weathered granite or acid volcanic rock, the environment will be acidic and the weathering may be fast. Acid rain will speed up the weathering. Penetrators and large pieces of DU can be collected if they can be located. Otherwise, the only way DU is removed is by gradual leaching by rain and melting snow. This weathering process of DU is principally by corrosion into hydrated uranium oxide (U(VI)) that is very soluble in water. Other possible uranium compounds may be more or less soluble in water. However, various adsorption effects in soil may slow the migration of uranium through soil in any case by several orders of magnitude, so it becomes essentially immobile. Consequently, it will take many years, maybe several hundred years, before DU contamination migrates from the site (see also Appendix V). |
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