Neutron Multiplication Factor — the NEET Physics formula with its derivation, variables, validity constraints and worked solver.
Neutron Multiplication Factor This factor characterizes the rate of change of neutrons in a nuclear chain reaction, determining whether the reaction is sustained, growing, or decaying. Define N n as the number of neutrons present in the current generation (generation n). Define N n+1 as the number of neutrons produced in the subsequent generation (generation n+1). The multiplication factor k is defined as the ratio of the neutrons produced to the neutrons consumed. Therefore, k = N n+1 N n . k > 0 k = 1: Critical state (sustained reaction) k > 1: Supercritical state (reaction accelerating) k < 1: Subcritical state (reaction slowing down) Confusing the multiplication factor k with the effective neutron cross-section ( ). Assuming k must always be greater than 1; k < 1 simply means the reaction is slowing down. Confusing the factor k with the total number of neutrons produced in a single fission event.