beam hole

noun
  1. a hole in the shield of a nuclear reactor through which a beam of radiation, esp of neutrons, is allowed to escape for experimental purposes
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Examples from the Web for beam hole

Historical Examples of beam hole

  • Through the beam-hole at the stern the water began to flow into the interior of the ship.