Per cent mille

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A per cent mille or pcm is one one-thousandth of a percent.[1] It can be thought of as a "milli-percent". It is commonly used in nuclear reactor engineering as a unit of reactivity.

See also[edit]

  • InHour (another unit of reactivity)


  1. ^ SCALE: A Comprehensive Modeling and Simulation Suite for Nuclear Safety Analysis and Design. Available from Radiation Safety Information Computational Center at Oak Ridge National Laboratory as CCC-785. Oak Ridge, TN: Oak Ridge National Laboratory, June, 2001. Version 6.1. ORNL/TM-2005/39