Definition of pebble bed in US English:

pebble bed


  • 1Geology a deposit of conglomerate containing pebbles, especially one from which they readily work loose with weathering.

  • 2Nuclear Physics a nuclear reactor in which the fuel elements are in the form of pellets, often with a coating of moderator; usually attributive.


Mid 19th century; earliest use found in Joseph Prestwich (1812–1896), geologist.