Question

Which of the following is used as a moderator in the reactor of a nuclear power station ?
(a) liquid sodium (b) boron (c) graphite (d) carbon dioxide

Answer 1

option c

In a nuclear power plant, the fission of uranium-235 is carried out in a reactor R. Uranium-235 rods are inserted in a graphite core which acts as a moderator to slow down the neutrons. However in a fast reactor there is no moderator, only fuel and coolant. The moderation of neutrons is undesirable in fast reactors. Commonly used moderators include regular (light) water (roughly 75% of the world's reactors), solid graphite (20% of reactors) and heavy water (5% of reactors).