Investigation of neutron noise behaviour in a fast reactor using a multi-group noise simulator

Neutron noise behaviour in a sodium-cooled fast reactor (SFR) has been investigated using a multi-group noise simulator. The noise simulator was developed based on diffusion theory with multi-energy groups and several groups of delayed neutron precursors for supporting monitoring fast reactor cores. Noise sources are modeled via small stationary fluctuations of macroscopic cross sections, and the induced first order noise is solved in a frequency domain. Numerical calculations have been performed based on a 2D model of the ESFR core with 33 energy groups and 8 groups of delayed neutron precursors. Localized perturbations of several cross section types near the center of the core were assumed to investigate the behaviour of the amplitude and phase of the induced space-dependent noise in a wide range of frequency, e.g. 0.1 - 100 Hz