Module 102 The Nuclear Fuel Cycle
Later investigators, such as Marie Curie, isolated other
radioactive elements from uranium ores. These elements
are produced from the radioactive decay of uranium. The
radioactive emission of an alpha particle causes uranium
to change into thorium. Thorium goes on to decay to other
elements, and so on, until a stable element such as lead is
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 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 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.