plutonium
noun
plu·to·ni·um
| \ plü-ˈtō-nē-əm
\
\
Definition of plutonium
: a radioactive metallic element similar chemically to uranium that is formed as the isotope 239 by decay of neptunium and found in minute quantities in pitchblende, that undergoes slow disintegration with the emission of an alpha particle to form uranium 235, and that is fissionable with slow neutrons to yield atomic energy — see Chemical Elements Table
Examples of plutonium in a Sentence
Recent Examples on the Web
The submarine sank in a mile of water, along with the onboard nuclear reactor and two nuclear torpedoes carrying plutonium. — Kyle Mizokami, Popular Mechanics, "30 Years Later, a Sunken Soviet Sub Is Still Leaking Radioactivity," 12 July 2019 The material is unrelated to weapons-grade plutonium that the department secretly shipped to the same site last year and is currently at the center of a legal battle with the state of Nevada in the 9th U.S. Circuit Court of Appeals. — CBS News, "Nevada congressman calls for Secretary Rick Perry to resign over nuclear waste disposal controversy," 11 July 2019 The aging facility about 60 miles north of Pyongyang was once the main source of its fissile material, turning out roughly enough plutonium each year for one atomic bomb. — Jon Herskovitz, Fortune, "Why the Trump-Kim Nuclear Show Is Set for Act Three," 20 June 2019 As the camera panned down to what would be the reactor's core, Kamalvandi stressed that piping could be replaced and the reactor could be built to make plutonium. — Nasser Karimi And Jon Gambrell, chicagotribune.com, "Iran speeds up uranium enrichment as Mideast tensions mount," 17 June 2019 The files were gathered in a two-year grand jury probe of the Rocky Flats plant outside Denver, which manufactured plutonium triggers for nuclear warheads and had a history of fires, leaks and spills. — USA TODAY, "Milestone rhino, Bigfoot shooting, jailed for feeding cats: News from around our 50 states," 1 Aug. 2019 The government spent $7 billion cleaning up 2 square miles (5 square kilometers) at the center of the site where the plutonium triggers were built. — Washington Post, "US can’t find files on investigation into nuclear arms plant," 30 July 2019 The documents being sought were subpoenaed by a grand jury that met from 1989 to 1992 to look into environmental crimes committed at Rocky Flats, which produced plutonium triggers for the nation’s nuclear arsenal throughout the Cold War. — Sam Tabachnik, The Denver Post, "More than 60 boxes of documents from the Rocky Flats grand jury probe have gone missing," 30 July 2019 But during the mission, the heat energy of the plutonium powering the RTGs has lost a small amount of efficiency per year. — David Grossman, Popular Mechanics, "How NASA Is Trying to Keep the Voyager 2 Satellite Alive," 15 July 2019These example sentences are selected automatically from various online news sources to reflect current usage of the word 'plutonium.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.
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More Definitions for plutonium
plutonium
noun
English Language Learners Definition of plutonium
: a radioactive element that is used to make nuclear energy and nuclear weapons
See the full definition for plutonium in the English Language Learners Dictionary
plutonium
noun
plu·to·ni·um
| \ plü-ˈtō-nē-əm
\
\
Kids Definition of plutonium
: a radioactive metallic chemical element formed from neptunium and used for releasing atomic energy
plutonium
noun
plu·to·ni·um
| \ plü-ˈtō-nē-əm
\
\
Medical Definition of plutonium
: a radioactive metallic element similar chemically to uranium that is formed as the isotope 239 by decay of neptunium and found in minute quantities in pitchblende, that undergoes slow disintegration with the emission of an alpha particle to form uranium 235, and that is fissionable with slow neutrons to yield atomic energy
—symbol Pu
— see Chemical Elements Table
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