Plutonium

BeschreibungPlutonium was first isolated and produced in 1941 at the University of California-Berkeley, by nuclear chemist Glenn T. Seaborg and his colleagues, Joseph W. Kennedy, Edwin M. McMillan, and Arthur C. Wahl. Minute amounts of plutonium exist naturally, but large amounts are produced in nuclear reactors when uranium absorbs an atomic particle such as a neutron. Natural occurrences of plutonium are very rare, but it can occur in a reaction called spontaneous fission. This type of reaction occurs when ores of uranium with a high localized concentration decay in the right conditions and produce small amounts of plutonium. Synthetic plutonium is produced in a controlled nuclear reactor when uranium-238 absorbs a neutron and becomes uranium-239, ultimately decaying to plutonium-239. Plutonium has at least 15 different isotopes. Different isotopes of uranium and different combinations of neutron absorption and radioactive decay create the different isotopes of plutonium. Plutonium was discovered during wartime; therefore, the majority of plutonium production was for nuclear weapons. Other plutonium applications range from being energy sources on deep space probes to small amounts providing power to heart pacemakers.

HistoryThe name of Pu derives from the planet Pluto, (the Roman god of the underworld). Pluto was selected because it is the next planet in the solar system beyond the planet Neptune and the element plutonium is the next element in the period table beyond neptunium. Plutonium was first synthesized in 1940 by American chemists Glenn T. Seaborg, Edwin M. McMillan, Joseph W. Kennedy and Arthur C. Wahl at Berkeley, California, in the nuclear reaction 238U(2H, 2n) 238Np → β − → 238Pu. The longest half-life associated with this unstable element is 80 million year 244Pu.

VerwendenThe principal plutonium isotopes, 239Pu and 240Pu, were produced as ingredients for nuclear weapons. It is estimated that the United States produced 400 kCi of plutonium for nuclear weapons testing, and approximately 325 kCi was dispersed globally into the environment from conducted aboveground tests. Overall, an estimated 500 aboveground nuclear tests were conducted between 1945 and 1963 by the Soviet Union, Britain, France, and the United States. From these tests, it is estimated 100 000 kCi of plutonium were dispersed into the environment.Applications for 238Pu include using it as a heat source for thermoelectric power devices. Radioisotope thermoelectric generators (RTGs) have been used to provide a source of power in remote locations, such as deep space probes. This plutonium isotope generates a large amount of heat through its decay process. The generated heat is converted into electric power via a thermocouple in the RTG. Small-scale application of 238Pu is also used to provide power to heart pacemakers. The concept behind the use of this material is a result of the half-life of the isotope, since its half-life is extremely long, changing out the power source is not necessary.