A nuclear reactor is said to be critical when the neutron population in the reactor core is

A. Rapidly increasing leading to the point of explosion

B. Decreasing from the specified value

C. Reduced to zero

D. Constant

Answer: Option D

Solution(By Examveda Team)

Criticality means that a reactor is controlling a sustained fission chain reaction, where each fission event releases a sufficient number of neutrons to maintain an ongoing series of reactions. This is the normal state of nuclear power generation.