What Are Depleted Uranium Munitions? Research, tests, and evaluations were conducted during the 1970s to develop improved armor-penetrating munitions capable of defeating a heavily armored target. High-density materials such as tungsten and depleted uranium were considered candidates for this type of munitions; depleted uranium was ultimately selected because of its very high density, availability, noncompetitive uses, and pyrophoricity (spontaneous combustion upon exposure to air).
The two main antitank weapons made of depleted uranium are the 120-millimeter (mm) cannon shell used by the Army's M1 Abrams tank, and the 30-mm munitions used by A-10 antitank aircraft. Depleted uranium weapons are also used in Britain's Challenger tank, and the U.S. and British Navy Phalanx gun systems. The M1 Abrams tank fires a 120-mm shell that contains a kinetic energy penetrator, a solid rod with a pointed tip. The penetrator is made from about 5 kilograms (kg) (11 pounds [lb]) of depleted uranium metal alloyed with less than 1% titanium. The shell is a sabot round, meaning that the penetrator is contained within a carrier as it is fired from the barrel. The carrier separates from the penetrator after exiting the gun barrel. In addition, many M1 Abrams tanks incorporate depleted uranium metal as part of the external armor.
Depleted uranium rounds are also fired by a 30-mm, seven-barrel gatling gun mounted in the nose of the A-10 Thunderbolt aircraft, the only U.S. military plane that employs depleted uranium rounds. Depleted uranium is the primary munition for the A-10 Thunderbolt for combat. Each 30-mm depleted uranium projectile contains approximately 0.3 kg (0.66 lb) of extruded depleted uranium metal alloyed with 0.75% titanium. The projectile is encased in a 0.8-mm-thick aluminum shell as the final depleted uranium round.
Depleted uranium penetrators have a “sharpening effect” upon impact that allows greater penetration through armor. Weapon testing shows that when a depleted uranium round penetrates an armored vehicle, it may pass completely through the vehicle or ricochet around and fragment inside the vehicle. Metal fragments from the penetrator and the vehicle’s hull can scatter inside the vehicle, killing and injuring personnel, destroying equipment, and causing secondary explosions and fires. As much as 70% of a depleted uranium penetrator can be aerosolized when it strikes a tank. Aerosols containing uranium oxides may contaminate the area downwind. Uranium metal and oxide fragments may also contaminate the soil around the struck vehicle. Tests of depleted uranium penetrators striking depleted uranium armored vehicles have shown that most of the contamination will occur within 5 to 7 meters (16 to 23 feet) of the vehicle.
For Whom Is Exposure a Concern? Soldiers can be exposed to depleted uranium when intact rounds are in storage or uploaded in armored vehicles, or on the battlefield following the use of depleted uranium munitions. Studies have shown that exposure to intact depleted uranium weapons systems, both munitions and armor, pose very little risk from external radiation. Uranium and its decay products are primarily alpha emitters, emitting only very low levels of gamma radiation. However, individuals involved in handling or processing depleted uranium generally wear heavy gloves to protect against the high-energy beta particle from protactinium-234m, which is only a concern for skin exposure.
On the battlefield, exposure to depleted uranium can occur several ways. After impact with an armored vehicle, depleted uranium in the form of oxide and metal fragments will contaminate the struck vehicle and the surrounding area, especially if an explosion or fire occurs. Depleted uranium oxide can be aerosolized, presenting an inhalation hazard to soldiers in the vicinity or downwind of the struck vehicle. In addition, depleted uranium dust can be resuspended in the air from soil contamination around the vehicle. Soil contamination also can be ingested inadvertently from hand to mouth contact. In another example of battlefield exposure, at least 36 soldiers in Operation Desert Storm were reported to have wounds involving imbedded depleted uranium fragments. (Many of these fragments were not removed because the risk of surgery was judged to be too great.) |
