Heavy water is used as a moderator in some nuclear reactors. Which property makes heavy water especially useful for this purpose?
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Question

Heavy water is used as a moderator in some nuclear reactors. Which property makes heavy water especially useful for this purpose?

G1 Physics · Accepted Answer

A good moderator should slow fast neutrons without capturing too many of them. Heavy water contains deuterium, which can reduce neutron kinetic energy through collisions while having a comparatively small neutron-absorption probability. Therefore many neutrons remain available to sustain the chain reaction after moderation. Correct option: B.