The aim of this work is investigate the stability effects of each term of fractional neutron point kinetics (FNPK) equations, taking special emphasis on the source term. The method applied in this work considers the transformation of the s-plane to the W-plane. Short and longs relaxation times for different values of fractional-order derivative were analyzed and the minimum absolute phase was obtained in order to establish the stability of the system. The results obtained shown that the source term are crucial in the FNPK instability.