Uranium-238 ? Odd, as that sounds like depleted uranium (U-238 is not fissionable)
from Wikipedia :
Depleted uranium (DU) is
uranium primarily composed of the
isotope uranium-238 (U-238). Natural uranium is about 99.27 percent U-238, 0.72 percent
U-235, and 0.0055 percent
U-234. U-235 is used for
fission in
nuclear reactors and
nuclear weapons. Uranium is
enriched in U-235 by separating the isotopes by mass. The byproduct of enrichment, called depleted uranium or DU, contains less than one third as much U-235 and U-234 as natural uranium. The external radiation dose from DU is about 60 percent of that from the same
mass of natural uranium.
[2] DU is also found in
reprocessed spent nuclear reactor fuel, but that kind can be distinguished from DU produced as a byproduct of uranium enrichment by the presence of
U-236.
[3] In the past, DU has been called
Q-metal,
depletalloy, and
D-38.
DU is useful because of its very high
density of 19.1
g/
cm3. Civilian uses include counterweights in aircraft, radiation shielding in medical
radiation therapy and industrial
radiography equipment, and containers used to transport radioactive materials. Military uses include defensive armor plating and
armor-piercing projectiles.
The use of DU in
munitions is controversial because of questions about potential long-term health effects.
[4][5] Normal functioning of the
kidney,
brain,
liver,
heart, and numerous other systems can be affected by uranium exposure, because in addition to being weakly radioactive, uranium is a
toxic metal.
[6] It is weakly radioactive and remains so because of its long
physical half-life (4.468 billion years for
uranium-238), but has a considerably shorter
biological half-life. The aerosol produced during impact and combustion of depleted uranium munitions can potentially contaminate wide areas around the impact sites or can be inhaled by civilians and military personnel.
[7] During a three week period of conflict in 2003 in
Iraq, 1,000 to 2,000 tonnes of DU munitions were used, mostly in cities.
[8]
The actual acute and chronic toxicity of DU is also a point of medical controversy. Multiple studies using cultured cells and laboratory rodents suggest the possibility of
leukemogenic,
genetic,
reproductive, and
neurological effects from chronic exposure.
[4] A 2005
epidemiology review concluded: "In aggregate the human epidemiological evidence is consistent with increased risk of birth defects in offspring of persons exposed to DU."
[9] The
World Health Organization states that no consistent risk of reproductive, developmental, or carcinogenic effects have been reported in humans.
[10][11] However, the objectivity of this report has been called into question.
[12]
