Appearance and Characteristics
Harmful effects:
Uranium is harmful both through its chemical toxicity and its radioactivity. Exposure to uranium increases your risk of getting a variety of cancers due to its radioactivity.
Characteristics:
Uranium is a dense, silvery-white, slightly paramagnetic, radioactive metal. It is also ductile and malleable. The metal tarnishes in air acquiring a dark layer of oxide. When finely powdered, uranium ignites spontaneously in air.
Uranium is a highly reactive metal and reacts with almost of all the nonmetallic elements and many of their compounds. It dissolves in acids, but it is insoluble in alkalis. All isotopes of uranium are radioactive, some more so than others. Its radioactivity – in particular its capacity to undergo thermonuclear chain reactions – has led to uranium’s use in energy generation, both for civilian and military purposes.
Uses of Uranium
Uranium is used as fuel for nuclear power plants. One kilogram of uranium-235 has the capacity to produce as much energy as 1,500,000 kilograms (1,500 tonnes) of coal.
Naturally occurring uranium is over 99% U-238 with only about 0.7% of the fissile U-235. Huge gas diffusion plants are used to produce enriched uranium, which has higher concentrations of U-235.
Uranium for use in nuclear power plants is enriched to a U-235 concentration of 2-3%.
In nuclear weapons, it is believed uranium is enriched to about 90% U-235, although lower concentrations would still yield a working bomb.
Depleted uranium is a byproduct of enriching uranium for nuclear purposes. It contains about 0.2% U-235 and is about half as radioactive as naturally occurring uranium.
Its lower radioactivity has allowed depleted uranium to be used in applications where uranium’s very high density is useful. (A tennis ball sized sphere of uranium would weigh about 5.7 pounds (2.6 kilograms).) It is used by the military as shielding to protect army tanks, and also in parts of bullets and missiles.
Use of depleted uranium in missiles is controversial because, on impact, uranium vapor and dust form and these are highly toxic.
U-238 can be converted into fissionable plutonium in breeder reactors.