Question:-
The most commonly used moderator in nuclear power plants is
Option (A)
heavy water
Option (B)
concrete and bricks
Option(C)
steel
Option(D)
graphite
Correct Option:
(A)
Question Solution:
A moderator is a material which is used to slow down neutrons from high velocities. The moderate should have a high macroscopic neutrons scattering cross-section, a low macroscopic neutrons absorption cross-section and a low atomic mass to get maximum kinetic energy transfer from neutrons to the moderator atoms. Actually only four isotopes are used in material to moderate neutrons. They are ordinary hydrogen (H-1), heavy hydrogen (H-2), beryllium and carbon.
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