Sources of Uranium - hdbk1113cn10124

DOE-HDBK-1113-98

Radiological Safety Traning for Uranium Facilities

Module 102 - The Nuclear Fuel Cycle

can accumulate in buildings and mines. Typically, these radioactive decay products are more

hazardous than the uranium itself.

The importance of uranium increased dramatically with the discovery of nuclear fission in 1938, the

production of plutonium in 1940, and the construction of the first reactor in 1942 under the direction

of Enrico Fermi. These accomplishments led to the Manhattan Project, in which uranium was

enriched at Oak Ridge or converted into plutonium at Hanford. These products were used to

assemble the first atomic bombs at Los Alamos in 1945.

After the end of World War II in 1945, the importance of uranium remained high. Production of

uranium a nd pluto nium for " atomic" o r "nucle ar" weap ons cont inued th roughout the Cold War. In

addition, nuclear reactors were built for the propulsion of naval submarines and ships, and for the

commercial production of electricity. Now, most of the world's production of uranium is used for

nuclear reactors.

C. Sources of Uranium

Uranium is found in the earth's crust and is mined as ore. The average concentration is 2 parts per

million (ppm) in the crust and less than 2 parts per billion (ppb) in the oceans. During the 1960's and

1970's, a program titled the Natural Uranium Resource Exploration was funded by the government to

identify the locations of desirable uranium ore throughout the United States. It was determined that

the most desirable locations of uranium are in the Colorado Plateau, the Wyoming Basin, and the

flanks of the Black Hills in South Dakota. In those locations, the uranium concentration is much

higher than 2 ppm. Uranium is also found on the African Continent. The ore is removed from either

shallow open pits (less than 300-foot, or100 m, depths) or underground mines (greater than 300-foot

depths). The typical uranium content of the ore is 0.15 - 0.3 percent and is in the form of U3O8,

which is called "yellowcake." Uranium is also found in secondary minerals in the following forms:

complex oxides, silicates, phosphates, and vanadates.