(T.A.E.C. Çekmece Nuclear Research And Training Center, 1973) Adalıoğlu, Ulvi; Duderstadt, J. J.; TAEK-ÇNAEM
The time decay constants characterizing the time behavior of a neutron pulse in a subcritical fast assembly are investigated by analyzing the time- eigenvalue spectrum of the transport operator for fast neutrons. To simplify this analysis, isotropic scattering was assumed, and a simple model of inelastic scattering was employed. By applying the techniques of functional analysis familiar from the study of the time-eigenvalue problem for thermal neutrons, it has been possible to classify the spectrum of the transport operator into the usual band spectrum for Re{s} ≤- λ*, where λ* is the minimum collision frequency, and a point spectrum in the region Re{s} > - λ* . It was demonstrated that this point spectrum was void for either sufficiently small assembly sizes or sufficiently small concentrations of fissile material.