The fissile properties of Plutonium-239
Plutonium-239 is an isotope of plutonium commonly used in nuclear reactors to produce nuclear weapons. The atoms of Plutonium-239 primarily disintegrate to release energy and gamma radiation when bombarded with slow-moving neutrons and are said to be a fissile isotope. Because of its fissile properties, plutonium-239 is used as a nuclear fuel in reactors to produce energy. It is also the major isotope used in the production of nuclear weapons alongside Uranium-238. It has an estimated half-life of 24,200 years; however, it undergoes fission when bombarded with neutrons to release energy, more neutrons, and radiations such as beta rays and gamma radiations.
Manufacture of Plutonium-239
Plutonium-239 is one of the primary fuels of nuclear reactors. It is generated through a fusion process involving Uranium-238 isotope (U-238) present in the nuclear fuel rods. The process involves exposing the Uranium-238 isotopes to a stream of neutrons, whereby the U-238 atoms capture the neutrons and transform them to Uranium- 239 (U-239). The U-239 formed undergoes beta decay by first releasing beta radiation to form Neptunium-239 followed by second beta decay to form plutonium-239 (Benedict & Thomas, 1981, p.81). The plutonium produced, however, is not pure and requires exposure into the air in the reactors to isolate pure plutonium-239 from the rest of the materials and make it an effective fissile material for use in nuclear reactors. However, the plutonium produced this way contains some contaminants notably plutonium-240. The formation of plutonium-240 is due to the tendency of Uranium-238 to take up an extra neutron during its formation.
Much of the plutonium-239 is manufactured in nuclear reactors called breeder reactors using fast-moving neutrons. They utilize less uranium-238 fuel but produce more plutonium-239 hence an efficient method of generating plutonium-239 from uranium fuel. However, the purity of plutonium-239 produced varies depending on the amount of the plutonium-240 present and the intended purpose. Plutonium-239 intended for the production of weapons contains a less percentage of plutonium-240, of up to 7% while plutonium-239 used as fuel in reactors contains 18% of the contaminant, plutonium-240.
Nuclear Power Reactors
In nuclear power reactors, uranium-238 is used as fuel alongside plutonium-239, which accumulates in the nuclear fuel. Plutonium-239 absorbs neutrons, which initiate a sustained chain-fission reaction. In the reactor core, plutonium-239 is constantly recycled thus eliminating any need for new fuel rods. During the fission process, large amounts of heat energy and radiations such as beta particles and gamma-ray are released (Hala & James, 2003, p. 102). The energy produced makes the reactor core very hot and requires a constant cooling system. In the Chernobyl nuclear accident, plutonium-239 was used as the fissile material for the nuclear reactors. The failure of the cooling system caused the nuclear core to become so hot leading to an explosion. The Chernobyl accident released major radioactive elements such as iodine-131 isotope, cesium-134 cesium-137, and plutonium-239. These elements are radioactive hence emit dangerous radiations such as gamma radiations into the environment.
Plutonium produced from the breeder reactors is not appropriate for use in nuclear reactors and in the production of nuclear weapons because of a significant amount of the contaminant plutonium-240 that it contains (The Institute for Energy and Environmental Research (IEER), 1992, p.11). In addition, plutonium-240 undergoes spontaneous fission producing harmful nuclear radiation making handling it difficult. The presence of plutonium-240 in the fuel rods used in reactors can cause a small explosion that affects the nuclear reactor core.
Reference List
Benedict, M., & Thomas, P. (1981). Nuclear Chemical Engineering. New York: McGrawHill.
Hala, J., & James, D. (2003). Radioactivity, Ionizing Radiation, and Nuclear Energy. London: Oxford Press.
IEER. (1992). Plutonium, Deadly Gold of the Nuclear Age. Massachusetts: International Physicians Press.