In the 1930s, scientists found that bombarding uranium metal with neutrons caused the nuclei of uranium atoms to break apart, or fission. One significant feature of this reaction was that very large amounts of energy were released during nuclear fission. The first practical application of this discovery was the atomic bomb, developed by scientists working in the United States in the early 1940s.

The atomic bomb takes advantage of the energy released during fission to bring about massive destruction of property and human life. However, every bomb blast is also accompanied by another event known as radioactive fallout. The term radioactive fallout refers to all radioactive dust and particles that fall to the earth after a nuclear explosion. This combination of dust and particles contains hundreds of isotopes formed when a uranium nucleus fissions. Iodine-131 and yttrium-98 are only two of the many isotopes that are...