Physicochemical Characterization of Capstone Depleted Uranium Aerosols I: Uranium Concentration in Aerosols as a Function of Time and Particle Size

Abstract

During the Capstone Depleted Uranium (DU) Aerosol Study, aerosols containing DU were produced inside unventilated armored vehicles (i.e., Abrams tanks and Bradley Fighting Vehicles) by perforation with large-caliber DU penetrators. These aerosols were collected and characterized, and the data were subsequently used to assess human health risks to personnel exposed to DU aerosols. The DU content of each aerosol sample was first quantified by radioanalytical methods, and selected samples, primarily those from the cyclone separator grit chambers, were analyzed radiochemically. Deposition occurred inside the vehicles as particles settled on interior surfaces. Settling rates of uranium from the aerosols were evaluated using filter cassette samples that collected aerosol as total mass over eight sequential time intervals. A moving filter was used to collect aerosol samples over time, particularly within the first minute after a shot. The results demonstrate that the peak uranium concentration in the aerosol occurred in the first 10 s after perforation, and the concentration decreased in the Abrams tank shots to about 50% within 1 min and to less than 2% after 30 min. The initial and maximum uranium concentrations were lower in the Bradley vehicle than those observed in the Abrams tank, and the concentration levels decreased more slowly. Uranium mass concentrations in the aerosols as a function of particle size were evaluated using samples collected in a cyclone sampler, which collected aerosol continuously for 2 h after perforation. The percentages of uranium mass in the cyclone separator stages ranged from 38 to 72% for the Abrams tank with conventional armor. In most cases, it varied with particle size, typically with less uranium associated with the smaller particle sizes. Neither the Abrams tank with DU armor nor the Bradley vehicle results were specifically correlated with particle size and can best be represented by their average uranium mass concentrations of 65 and 24%, respectively.

Wounding characteristics and treatment principles of ground anti-armored vehicle ammunition against armored crew

“… 17 The resulted metal particles may be rapidly oxidized in the air, then form oxide powder aerosols, which enter the human body by respiration, oral and wound contamination, even embedded in the human body. 18 , 19 , 20 , 21 After DU absorbed through respiration and digestive tract, they will enter the circulation, then mainly deposited in the alveoli and bones. Uranium in body is mainly excreted by the kidney, with excretion rate more than 90% within 24 h, and completely eliminated within 340 days.…”

“…Uranium in body is mainly excreted by the kidney, with excretion rate more than 90% within 24 h, and completely eliminated within 340 days. 18 …”

Health Effects of Particulate Uranium Exposure

“…An important parameter is the activity median aerodynamic diameter (AMAD) [ 35 ], which refers to the value of the particle size of 50% of the cumulative activity distribution. The deposition and retention of aerosols in the respiratory system is a difficult subject for experimental studies, which relates to the degree of dissolution [ 36 ] and absorption of these particles in body fluids after inhalation [ 37 , 38 ], as well as to particle size distribution [ 39 , 40 ] and aerodynamic properties [ 41 ]. Therefore, the fine particle fraction (FPF) of aerosols is defined, referring to the number/fraction of aerosols below the 0.1, 1, and 2.5 μm range [ 42 ].…”

Ultrafine particle size distribution during high velocity impact of high density metals

“…For example, the U.S. Army performed the Capstone Depleted Uranium (DU) Aerosol Study to provide information on the amount and characteristics of aerosol particles generated in or near vehicles hit by a large-caliber DU penetrator striking an Abrams or Bradley test vehicle [9][10][11][12]. Such studies reported measurements of mass particle concentration decay over time and mass particle distribution inside and outside tanks: total mass concentrations of thousands of mg m -3 were detected inside the tanks [8,11,12].…”