| 释义 |
plutonium|pluːˈtəʊnɪəm|
[L. Plūtōnium, ad. Gr. Πλουτώνιον, f. Πλούτων Pluto.]
1. A place where there are mephitic vapours.
1775R. Chandler Trav. Asia M. (1825) I. 292 Hierapolis was noted, besides its hot waters, for a Plutonium. Ibid. 294, I renewed my inquiries for the Plutonium, and an old Turk..told me he knew the place, that it was often fatal to goats.
2. Chem.
†a. = barium. Obs.
The word was introduced in a letter to the Royal Institution dated 1 Sept. 1816, but not published until 1817 (= quot. 1817 below). Its first occurrence in print was in Ann. de Chim. et de Physique (Sept. 1816) III. 61 in a Fr. transl. of it. Quot. 1816 is from a letter of 5 Oct. 1816 that refers to this (then unpublished) letter.
1816E. D. Clarke in Ann. Philos. VIII. 358 The metal is in its purest state. It is the same metal for which I proposed the appellation of Plutonium; and I am glad to find the appellation generally approved. Ibid. 360 Plutonium, if fused in contact with platinum, always tarnishes the latter. 1817― in Jrnl. Sci. & Arts II. 120 The existence..of the metal of Barytes no longer admits of the smallest doubt... As any derivative from βαρυς would involve an error, if applied to a metal whose specific gravity is inferior to that of Manganese or Molybdenum, I have ventured to propose for it the appellation of Plutonium; because we owe it entirely to the dominion of fire.
b. A transuranic metallic element which is formed indirectly from uranium in nuclear reactors and occurs naturally in trace amounts, is chemically similar to uranium, and is very reactive; the longest-lived isotope (plutonium 244) has a half-life of 83 million years, and plutonium 239 is fissile and is produced for use in nuclear weapons and as fuel. Atomic number 94; symbol Pu. [So called from its being the next element after neptunium in the periodic table, as Pluto is the planet next beyond Neptune.]
1942Seaborg & Wahl Chem. Properties Elem. 94 & 93 (U.S. Office Sci. Res. & Devel. Report A-135) 17 Since such formulae are confusing when the symbols ‘93’ and ‘94’ are used, we have decided to use symbols of the conventional chemical type to designate these elements. Following McMillan, who has suggested the name neptunium..for element 93, we are using plutonium..for element 94. The corresponding chemical symbols would be Np and Pu. 1952J. G. Feinberg Atom Story xx. 153 On 20th December 1943 the first batch of irradiated slugs were removed from the pile for plutonium extraction. In another month the pile was turning out about one-third ton of plutonium-enriched slugs a day. 1962J. C. Wright Metallurgy in Nucl. Power Technol. iii. 60 The concentration of plutonium in minerals such as pitchblende is no more than one part in 1011. 1964R. L. Loftness Nucl. Power Plants ii. 63 The maximum permissible body burden for plutonium is 0·3 microgram, and such a low limit requires the use of very efficient enclosures, or glove-boxes, for all research, development, and production work. 1968[see neptunium]. 1969Times 22 Apr. 6/6 Scientists..claimed to have synthesized element 104..by bombarding plutonium with neon. 1970Daily Tel. 23 July 3/2 The nuclear-powered pacemaker—shaped like a small bullet and powered with plutonium 238—has a life of about 10 years. 1970tr. Vol'skii & Sterlin's Metallurgy of Plutonium i. 19 Pure plutonium cannot be used as a nuclear fuel because of its low melting point, poor mechanical properties, high chemical activity, and the considerable volume changes caused by phase transformations... For reactors plutonium alloys and plutonium compounds are used. 1976Sci. Amer. Dec. 30/2 In addition to uranium 235 the spent fuel contains between ·7 and 1 per cent of plutonium 239, synthesized from uranium 238 by the absorption of a neutron. 1979Ibid. Apr. 33/2 A Precambrian mineral, a rare-earth fluocarbonate mined for cerium in California, has yielded the all but extinct isotope of plutonium with mass 244.
3. attrib. and Comb., as (sense 2 b) plutonium economy, plutonium enrichment; plutonium bomb, an atomic bomb in which the fissile material is plutonium.
1948C. Pincher Into Atomic Age 53 Three days after the attack on Hiroshima..the plutonium bomb was dropped on Nagasaki. Ibid. 54 The ‘Mark II’ plutonium bomb was a definite improvement. It would have devastated the flat, round target of Hiroshima more completely than did the now obsolete uranium ‘Mark I’. 1973Guardian 19 Apr. 14/3 To make a plutonium bomb, with which a criminal could hold a city to ransom..one needs just 16·2 kilos of the metal. 1976New Yorker 9 Feb. 44/3 Such a ‘plutonium economy’, in which fissionable fuel is recycled between reactor and reprocessing plant, is essential to the operation of the breeder. 1977Jrnl. R. Soc. Arts CXXVI. 15/2 The distinguished Royal Commission under Sir Brian Flowers has expressed disquiet about a ‘plutonium economy’, but that is not to condemn all nuclear development. 1977Time 7 Mar. 7/1 West German officials are further incensed over Carter's public criticism of Bonn's deal to sell a plutonium-enrichment plant and eight nuclear reactors to Brazil. |