Investigation of the Space- and Energy-Dependent Coherence Function in Zero-Power Coupled-Core Reactors

An investigation of the kinetic characteristics of coupled-core reactors using noise analysis techniques is undertaken. It is shown that time- and frequency-domain methods of noise analysis are closely related and their particular space-dependent forms arise from the manner in which the impulse response or transfer function is approximated. Using an analytical and two modal expansion approximations of the neutron noise, the significance of the coherence function frequency characteristics under varying hypothetical detector placements and core conditions is interpreted. Coherence function computational results using a one-dimensional, two neutron-energy group diffusion theory model provide good agreement with measurements.