GENERAL KNOWLEDGE

Detailed explanation-1: -In a nuclear reactor, moderators slow down the neutrons which come out in a fission process. The moderator used have light nuclei. Heavy nuclei will not serve the purpose because. substances with heavy nuclei do not occur in liquid or gaseous state at room temperature.

Detailed explanation-2: -Moderators are used to slow down neutrons in a nuclear reactor. ∴ Answer is Moderator.

Detailed explanation-3: -In nuclear engineering, a neutron moderator is a medium that reduces the speed of fast neutrons, ideally without capturing any, leaving them as thermal neutrons with only minimal (thermal) kinetic energy.

Detailed explanation-4: -A moderator is a material used in a nuclear reactor to slow down the neutrons produced from fission. By slowing the neutrons down the probability of a neutron interacting with 235U nuclei is greatly increased thereby maintaining the chain reaction.

Detailed explanation-5: -Neutron moderators are a type of material in a nuclear reactor that work to slow down the fast neutrons produced by fission to make them more effective in the fission chain reaction. A separate moderator material is required because certain materials are better moderators than others.