Question

Moderator serve what purpose for commerical nuclear power plants in the US?

1:Conserve boron

2:Shut down the chain reaction

3:Speed up neutrons

4:Absorb radiation

5:Slow down neutrons

Answer 1

Ans) 5:Slow down the neutrons

In commercial nuclear power plant in US we use moderator for reducing the speed of fast neutrons because by this we convert them into thermal neutrons capable of sustaining a nuclear chain reaction involving uranium-235 or a similar fissile nuclide.

Commonly used moderators are

• regular (light) water (roughly 75% of the world's reactors)
• solid graphite (20% of reactors) and heavy water (5% of reactors).
• Beryllium has also been used in some experimental types.
• Hydrocarbons have been suggested as another possibility.