Question

Which is used as moderator in a nuclear reaction?

• A. H₂O
• B. Alum
• C. D₂O
• D. Any of these

Answer 1

Answer:

C. D₂O

In a nuclear reactor, a moderator is used to slow down the neutrons released by fission to increase the probability of subsequent fission reactions.

Common Moderators:

Some common materials used as moderators in nuclear reactors are:

• D₂O (Heavy Water): Deuterium oxide, also known as heavy water, is a common moderator used in nuclear reactors, particularly in CANDU reactors.

• H₂O (Light Water): Ordinary water is also used as a moderator in many nuclear reactors, including pressurized water reactors (PWRs) and boiling water reactors (BWRs).

• Graphite: Graphite is another material used as a moderator in some nuclear reactors, such as gas-cooled reactors.

Properties of a Good Moderator:

A good moderator should have the following properties:

• Low neutron absorption cross-section

• High neutron scattering cross-section

• High density