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Uranium What is Uranium Uranium Geology Uranium Deposits Uranium Resources Uranium Mining Uranium Logs

What is Uranium?


Uranium was formed in our solar system by supernova events billions of years ago. Today, its slow radioactive decay provides the main source of heat inside the earth's crust. Uranium is a heavy metal that can be used as an abundant source of concentrated energy. It usually occurs as an oxide; one primary uranium mineral is uraninite (UO2). Uranium metal is about 60 percent denser than lead and almost as dense as gold. It occurs in trace amounts nearly everywhere on the planet, even in seawater.

Uranium was discovered in 1789 by German chemist Martin Klaproth in an ore known as pitchblende. It was named after the planet Uranus discovered eight years earlier.

Clean Energy Source

Nuclear energy produced from uranium is recognized as a practical, inexpensive, and clean source of energy. A typical 1,000-megawatt reactor can provide enough electricity for a modern city of up to 1 million people. Nuclear power is reliable, and power plants emit no carbon dioxide. The emissions coming from the massive towers of a nuclear plant are actually water vapor. Nuclear power boasts the best capacity factor of all forms of electrical generation. The capacity factor of a power plant is the ration of its actual output for a period of time to its potential output if it were possible to operate at full capacity as designed and engineered for that same period of time. A nuclear power plant can run at above 90 percent capacity; a coal-fired plant runs at about 64 percent, natural gas power plant at 43 percent, and hydroelectric plant at 40 percent.
Power Plant

In a nuclear-fueled power plant, water is turned into steam, which drives turbine generators to produce electricity. The main difference between a nuclear power plant and a coal- or natural gas-fired power plant is the source of heat. At a nuclear power plant, the heat to make the steam is created when uranium atoms split by a process called fission. There is no combustion in a nuclear reactor, as opposed to those powered by fossil fuels.

Properties of Uranium

Uranium occurs naturally as three primary isotopes (elements with the same number of protons but a different number of neutrons). More than 99 percent of all uranium is 238U (atomic weight 238, or about 238 times the weight of one hydrogen atom and 13 times denser than the same volume of water), and less than 1 percent is in the form 235U. The 235U isotope is less stable and thus decays more rapidly than 238U, the isotope used as fuel in nuclear reactors.


Naturally occurring uranium is found as 238U (99.284 percent of all uranium found in nature), 235U (0.711 percent), and a very small amount of 234U (0.0058 percent). Other isotopes of uranium are known but are very rare and usually short-lived. Uranium decays slowly by emitting alpha particles. An alpha particle emitted from the uranium nucleus is positively charged and made up of two protons and two neutrons, which is physically and chemically identical to a helium nucleus. The 238U isotope is useful in dating the ages of some rocks and geologic events.

Uranium Atom

The nucleus of the 235U atom comprises 92 protons and 143 neutrons (92 + 143 = 235). When the nucleus of a 235U atom captures a moving neutron it splits in two (fission reaction) and releases energy in the form of heat and radiation, and two or three additional neutrons are expelled from the nucleus. If enough of these expelled neutrons cause the nuclei of nearby 235U atoms to split, releasing additional energy and neutrons, a fission 'chain reaction' can be achieved. When this happens repeatedly, many millions of times, a very large amount of heat is produced from a relatively small amount of uranium.

Military Uses
  • Nuclear reactors to power naval vessels
  • Nuclear (atomic) warheads
  • Chemical catalysts
  • Military aircrafts and space vessels
  • Shielding materials
  • Civil Uses of Nuclear Technology
  • Electrical generation
  • Hydrogen production for chemical and petroleum refining
  • Shielding for industrial radiography cameras
  • Depleted uranium used in sailboat keel
  • Aircraft trim weights
  • Inertial guidance systems and compasses
  • Research reactors
  • Radioisotopes from nuclear reactors:
    • Agriculture – insect control, fertilizer tracers to maximize beneficial use
    • Consumer products – smoke detectors, watches and clocks, non-stick materials (Teflon)
    • Food – irradiation to kill bacteria, sterilize packaging
    • Medicine – diagnosis, cancer treatment, sterilization
    • Water resources – pollution detection, analysis, and control, resource planning and management

    Source: World Nuclear Organization

    Kelsey Kehoe (307) 766-2286 Ext. 233