Radiological Safety Training for Uranium Facilities
Module 102 The Nuclear Fuel Cycle
Radium and radon are the two most well-known radioactive decay products of
uranium. Radium was once used for luminous instrument dials and other products.
Radon is a heavy radioactive gas that can accumulate in buildings and mines.
Typically, these radioactive decay products are more hazardous than the uranium
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 and plutonium for "atomic" or "nuclear" weapons continued
throughout 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.
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, or