Interpretation of Pulsed-Neutron-Source Experiments in a Multiregion Reactor

Abstract

By expanding the static flux into kinetic fluxes containing the fundamental and higher modes, we derive a kind of inhour equation which can express kinetic distortion, and can relate the static reactivity to prompt decay constants and to kinetic and adjoint fluxes. The equation is developed using the time-dependent, multigroup diffusion approximation, and is applied to the interpretation of pulsed-neutron-source experiments in a multiregion reactor. It is shown from this application that the Simmons-King formula can express the dynamic reactivity only under conditions of constant generation time and no kinetic distortion, and that the conventional in-hour equation derived by the perturbation method cannot distinguish between the static and dynamic reactivities differing from each other on account of kinetic distortion.