#moderator.inhibitor  any substance used to slow down neutrons in nuclear reactors
  supertype:  inhibitor  a substance that retards or stops an activity
  part of:  nuclear_reactor
  subtype:  heavy_water__heavywater__deuterium_oxide__deuteriumoxide  water containing a substantial proportion of deuterium atoms, used in nuclear reactors

No statement uses or specializes moderator.inhibitor; click here to add one.