A heavy, radioactive, metallic element (atomic number 94) that is similar to uranium. It undergoes fission when bombarded with neutrons and is used in the production of nuclear energy and the explosion of nuclear weapons. It occurs in nature in trace amounts, but is also produced as a byproduct of the fission reaction in a uranium‐fuelled nuclear reactor, and can be recovered for future use. See also breeder reactor.
Subjects: Environmental Science.