| 单词 | pebble bed |
| 释义 | > as lemmaspebble bed pebble bed n. (a) Geology a deposit of conglomerate containing pebbles, esp. one from which they readily work loose with weathering; (b) Nuclear Physics a nuclear reactor in which the fuel elements are in the form of pellets, often with a coating of moderator; usually attributive. ΘΚΠ the world > the earth > structure of the earth > constituent materials > rock > composite rock > [noun] > conglomerate > specific pinnel1766 grauwacke1794 unguilite1799 greywacke1805 yolky-stone1805 nagelfluh1808 coombe rock1822 pebble bed1849 breccia1856 ceppo1881 banket1886 ouklip1892 crush-conglomerate1893 basal conglomerate1900 calcrete1902 rudite1904 fanglomerate1912 beach-rock1919 1849 J. Prestwich in Q. Jrnl. Geol. Soc. 5 46 To commence with the pebble bed ‘b’. 1914 J. Park Text-bk. Geol. xxviii. 377 The three main divisions of the Trias recognised in the British Isles are:—3. Rhætic... 2. Keuper... 1. Bunter... The Bunter consists of red and variously hued sandstones and conglomerates or pebble beds of fluviatile or fluvio-lacustrine origin. 1961 New Scientist 16 Mar. 695/1 W. Germany is to have what is probably the first operational ‘pebble-bed’ reactor... The fuel elements are balls of graphite with centres of uranium carbide. 1969 G. M. Bennison & A. E. Wright Geol. Hist. Brit. Isles xii. 274 The Bunter Pebble Beds characteristically occur in the Midlands... The name Pebble Beds is a descriptive term and the formation comprises sandstone with pebbles. 1989 New Scientist 4 Nov. 60/2 West German reactors use a ‘pebble bed’ core in which the fuel particles are contained within small spheres of graphite, 6 centimetres across. < as lemmas |
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