< 1
= 1
1
1
Reproduction factor k is the number of neutrons in one generation per neutron in the preceding generation. If k is greater than 1, the chain reaction is supercritical, and the neutron population will grow exponentially. If k is less than 1, the chain reaction is subcritical, and the neutron population will exponentially decay. If k = 1, the chain reaction is critical and the neutron population will remain constant.