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DictionarymoderatorNeutron slowing
noun

moderator

A substance or device that slows neutrons in a nuclear reactor.

The reactor uses graphite as a moderator to slow neutrons.

Etymology
moderatorLatinregulator or controller

The Latin source means regulator or controller. In a nuclear reactor, a moderator regulates neutron speeds by slowing them, making the general controlling sense technically specific.

More examples

  • Water serves as both coolant and moderator in this reactor.
  • Heavy water is an effective moderator because it absorbs few neutrons.
  • Fast reactors operate without a moderator.

Forms

moderator · moderators

moderation noun — The slowing of neutrons in a reactor.

moderate verb — To slow neutrons in a nuclear reactor.