Longman Dictionary of Contemporary English
Douglas Harper's Etymology Dictionary
transuranic element, 1942, from Pluto, the planet, + element ending -ium. Discovered at University of California, Berkeley, in 1941, the element named on suggestion of Seaborg and Wahl because it follows neptunium in the periodic table as Pluto follows Neptune in the Solar System. The name plutonium earlier had been proposed for barium and was sometimes used in this sense early 19c.
n. The transuranic chemical element with atomic number 94 and symbol Pu.
n. a solid silvery gray radioactive transuranic element whose atoms can be split when bombarded with neutrons; found in minute quantities in uranium ores but is usually synthesized in nuclear reactors; 13 isotopes are known with the most important being plutonium 239 [syn: Pu, atomic number 94]
Plutonium is a radioactive chemical element.
Plutonium may also refer to:
- a ploutonion , any of several places where the Greco-Roman god Pluto was worshipped, particularly
- Pluto's Gate, the plutonium near the hot springs at Pamukkale in Turkey (ancient Phrygian Hierapolis)
- Plutonium, a fictional drug depicted in Clark Ashton Smith's "The Plutonium Drug"
- Plutonium, a genus of centipedes in the family Plutoniumidae
Plutonium is a transuranic radioactive chemical element with symbolPu and atomic number 94. It is an actinide metal of silvery-gray appearance that tarnishes when exposed to air, and forms a dull coating when oxidized. The element normally exhibits six allotropes and four oxidation states. It reacts with carbon, halogens, nitrogen, silicon and hydrogen. When exposed to moist air, it forms oxides and hydrides that can expand the sample up to 70% in volume, which in turn flake off as a powder that is pyrophoric. It is radioactive and can accumulate in bones, which makes the handling of plutonium dangerous.
Plutonium was first produced and isolated on December 14, 1940 by Dr. Glenn T. Seaborg, Joseph W. Kennedy, Edwin M. McMillan, and Arthur C. Wahl by deuteron bombardment of uranium-238 in the 60-inch cyclotron at the University of California, Berkeley. They first synthesized neptunium-238 (half-life 2.1 days) which subsequently beta-decayed to form a new heavier element with atomic number 94 and atomic weight 238 (half-life 87.7 years). It was fitting that element 94 be named after the next planetoid, Pluto following the precedents that uranium was named after the planet Uranus and neptunium after the planet Neptune. Wartime secrecy prevented them from announcing the discovery until 1948. Plutonium is the heaviest primordial element by virtue of its most stable isotope, plutonium-244, whose half-life of about 80 million years is just long enough for the element to be found in trace quantities in nature. Plutonium is much more common on Earth since 1945 as a product of neutron capture and beta decay, where some of the neutrons released by the fission process convert uranium-238 nuclei into plutonium-239.
Both plutonium-239 and plutonium-241 are fissile, meaning that they can sustain a nuclear chain reaction, leading to applications in nuclear weapons and nuclear reactors. Plutonium-240 exhibits a high rate of spontaneous fission, raising the neutron flux of any sample containing it. The presence of plutonium-240 limits a plutonium sample's usability for weapons or its quality as reactor fuel, and the percentage of plutonium-240 determines its grade ( weapons-grade, fuel-grade, or reactor-grade). Plutonium-238 has a half-life of 88 years and emits alpha particles. It is a heat source in radioisotope thermoelectric generators, which are used to power some spacecraft. Plutonium isotopes are expensive and inconvenient to separate, so particular isotopes are usually manufactured in specialized reactors.
Producing plutonium in useful quantities for the first time was a major part of the Manhattan Project during World War II that developed the first atomic bombs. The Fat Man bombs used in the Trinity nuclear test in July 1945, and in the bombing of Nagasaki in August 1945, had plutonium cores. Human radiation experiments studying plutonium were conducted without informed consent, and several criticality accidents, some lethal, occurred after the war. Disposal of plutonium waste from nuclear power plants and dismantled nuclear weapons built during the Cold War is a nuclear-proliferation and environmental concern. Other sources of plutonium in the environment are fallout from numerous above-ground nuclear tests, now banned.
Usage examples of "plutonium".
Oppy and Groves droned on about problems of the isolation of isotopes and allotropic states of plutonium, Joe wondered why he had gone to bed with Mrs Augustino.
May 1946, when a safety trainer was demonstrating how to perform a critical experiment with a beryllium cap over a plutonium sphere.
By a millimetre or so, the plutonium core was simply too big, or the hollow inside the bomb was too small.
Beside their primary purpose of plutonium production, they furnished heat for the sea-water distillation and chemical extraction system, processing the water that was run through the steam boilers at the main power reactors, condensed, redistilled, and finally pumped, pure, into the water mains of New York.
I recall, there have to be several subcritical masses of plutonium, or U-235, or whatever, blown together by shaped charges of explosive, all of which have to be fired simultaneously.
No one could quite believe Dieter was so lost to self-control, yet his words hung in the supercharged air like a subcritical mass of plutonium, and they waited breathlessly for the explosion.
But there was another way to breed plutonium, by means of a high-energy, unmoderated pile of natural uranium somewhat enriched.
The story of how the plutonium had been smuggled from Chelyabinsk to Vladivostok to Yongbyon, despite the efforts of the Russian government, the Chinese, and the Russian mafia, was a small epic in itself.
Albuquerque and through the lower valley, crossing the Rio so often it seemed a dozen rivers, Oppy and Groves discussed problems ranging from plutonium assembly to sugar for the commissary.
Its atmosphere bore no trace of the fluorocarbons or chloride plastics or plutonium that he would have expected to find there.
Now if that bomb casing only remains intact, and its plutonium is kept from scattering on the seafloor, we will all finally be able to rest easier.
Ships docked to load up our national products, goods transported from Stalingrad, Stalinsk, Stalino, Stalinbad, Stalinir, Stalinkan, and Stalinovo, goods to be sent forth to a waiting world: caviar and sables, vodka and papirosi, heroin and hashish, plutonium and red mercury, balalaikas, matryoshkas, lapel pins, rayon banners, platinum busts of our leaders, and coypu.
The torchman finished fitting the plutonium and carried the block to the tube opening.
Randy, Babs, and Yoke uvvied inward, examining their alla catalogs, and sure enough, plutonium was listed.
The explosive in this device crushes and implodes a plutonium core into a critical mass.