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Definition of "plutonium" []

  • A naturally radioactive, silvery, metallic transuranic element, occurring in uranium ores and produced artificially by neutron bombardment of uranium. Its longest-lived isotope is Pu 244 with a half-life of 76 million years. It is a radiological poison, specifically absorbed by bone marrow, and is used, especially the highly fissionable isotope Pu 239, as a reactor fuel and in nuclear weapons. Atomic number 94; melting point 640°C; boiling point 3,235°C; specific gravity 19.84; valence 3, 4, 5, 6. See Table at element. (noun)
  • A highly toxic metallic transuranic element. It occurs in trace amounts in uranium ores and is produced in a nuclear reactor by neutron bombardment of uranium-238. The most stable and important isotope, plutonium-239, readily undergoes fission and is used as a reactor fuel in nuclear power stations and in nuclear weapons. Symbol: Pu; atomic no: 94; half-life of 239Pu: 24 360 years; valency: 3, 4, 5, or 6; relative density (alpha modification): 19.84; melting pt: 640°C; boiling pt: 3230°C (noun)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

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Use "plutonium" in a sentence
  • "“I'm sure that in 1985 plutonium is available in every corner drugstore, but in 1955 it's a little hard to come by.”"
  • "In 2007, North Korea shut down its main plutonium-producing plant and agreed to end all nuclear programs in exchange for aid and diplomatic concessions."
  • "The half-life of (radioactive) plutonium is about 77,000 years."