Which of the following are true about moderators used in nuclear reactors? A.…
2025
Which of the following are true about moderators used in nuclear reactors?
A. Moderators slow down neutrons to sustain the chain reaction
B. Moderators stop the neutrons to control the chain reaction
C. Without a moderator, a chain reaction would stop
D. Example of a moderator is a graphite rod
- A.
A and C Only
- B.
B and D Only
- C.
A, C, and D Only
- D.
B, C, and D Only
Attempted by 7 students.
Show answer & explanation
Correct answer: C
In nuclear reactors, moderators are used to slow down fast neutrons produced during fission. These fast neutrons must be slowed to thermal energies to effectively cause further fission in fuel like Uranium-235, sustaining the chain reaction. Therefore, statement A is correct.
Control rods, not moderators, are responsible for absorbing neutrons to stop or regulate the reaction rate. Thus, statement B is incorrect.
Without a moderator in thermal reactors, neutrons remain too fast to sustain the chain reaction efficiently, making statement C correct. Common moderator materials include graphite and heavy water, validating statement D.
Consequently, the correct combination includes statements A, C, and D.