Wikipedia:Today's featured article/February 23, 2009

Plutonium is a rare transuranic radioactive element. It is a radiological poison that accumulates in bone marrow, although its overall toxicity is sometimes overstated. The most important isotope of plutonium is plutonium-239, which is fissile, meaning Pu-239 atoms inside a critical mass of the isotope can break apart relatively easily and release a great deal of energy and more neutrons to sustain a nuclear chain reaction. This property makes it useful in nuclear weapons and in some nuclear reactors. The discovery of plutonium by a team led by Glenn T. Seaborg in 1940 became a classified part of the Manhattan Project to build an atomic bomb during World War II. The first nuclear test, "Trinity" (July 1945) and the atomic bomb used to destroy Nagasaki, Japan in August 1945, "Fat Man", both had cores of Pu-239. Disposal of plutonium waste from nuclear power plants and dismantled nuclear weapons built during the Cold War is a major concern. Most plutonium in the environment is from the fallout from above-ground nuclear tests and from several nuclear accidents. (more...)

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