Uranium

In 1789, a German chemist named Martin Heinrich Klaproth was working on an experiment in his laboratory in Berlin. He was able to precipitate a yellow compound by dissolving pitchblende in nitric acid and neutralizing the solution with sodium hydroxide. He heated the substance with charcoal and produced a black powder, which he thought was a newly discovered metal. Turns out the powder was a uranium oxide. He named the newly discovered element uranium. In 1841, Eugène-Melchoir Péligot, a French chemist, isolated the first sample of uranium metal.

In 1896, Henri Becquerel, a French physicist and engineer, discovered the radioactivity of uranium in one of the most well-known accidental discoveries of physics. He unintentionally left a sample of uranium salt on top of an unexposed photographic plate, noting later that the plate had become fogged. He determined that a form of invisible light or rays emitted by uranium had exposed the plate. Serendipitously, radioactivity was discovered.

During World War I, there was a shortage of molybdenum to make artillery gun barrels. As a substitute, ferrouranium was used instead. In 1916, the US government requested that several prominent universities research the use of uranium in manufacturing and metalwork. Then, in 1942, came the Manhattan Project and the world would never be the same. Uranium became part of fission research and weapon development. The rest, as they say, is history.

Uranium is a silvery white, weakly radioactive metal that corrodes to a black oxide in air. Uranium is a solid at room temperature and is hard enough to scratch glass. It is malleable, ductile, and a poor electrical conductor. It reacts with almost all non-metal elements and their compounds. Uranium is highly soluble so it can be easily dissolved, transported, and precipitated within groundwater.

Uranium is the heaviest naturally occurring element and is actually more abundant than silver. It has the largest energy density of any of the world’s fuels used for generating electricity. Uranium is fissile and fissionable, describing how easily the atom can be split.

Uranium was first used in the year 79 CE to add a yellow color to ceramic glazes. That use continued into the Middle Ages. More recently, it was used to produce a ceramic glaze for Fiesta® ware, brightly colored dishware, from the 1930s to 1970s. This use was discontinued for health reasons.

Uranium continues to be used in nuclear reactors and nuclear weapons. It is also used in inertial guidance devices, gyro compasses, as counterweights for aircraft control surfaces, and ballast for missile reentry vehicles. It has many military uses. Uranium is also used for x-ray targets in the production of high-energy x-rays.

Uranium is used in scientific research, i.e., estimating the age of igneous rocks and other types of radiometric dating. It is also used for diagnosis and medical research.

Uranium has 28 isotopes that have been identified, ranging in mass number from 214 to 242. Naturally occurring uranium is composed of three isotopes. Of the three, uranium-238 makes up 99.28%, uranium-235 makes up 0.71%, and uranium-234 makes up 0.0054%.

Uranium's most stable isotope, uranium-238, has a half-life of about 4.5 billion years. Uranium-235, with a half-life of 704 million years, is the only naturally occurring isotope, and the only naturally occurring fissile material. It is also rare in nature.

Uranium-236 has a half-life of about 23 million years. It is not found in significant quantities in nature. Uranium-235 has a half-life of 245,500 years. Uranium-233 has a half-life of 160,000 years and, like 235U, is fissile.

Uranium-232 has a half-life of 68.9 years and is actually considered a nuisance; its decay products emit dangerously high gamma radiation. It won’t turn you into the Hulk, but this radiation is a huge safety concern and it complicates handling and processing. All other uranium isotopes have half-lives shorter than one hour.

Depleted uranium is the main by-product of uranium. It is the form of uranium that happens when most of the highly radioactive isotopes are removed. It is highly dense.

Uranium is a common element found in soil, rock, water, food, and animals. It is also found in numerous natural minerals such as pitchblende, uraninite, carnotite, autunite, uranophane, and tobernite; and in phosphate rocks, lignite, and monazite sands.

It is found in the Oklo natural nuclear fission reactor in West Africa.