Neutron/Nuclei Balance — The Fission Source

Abstract

The distribution of the neutron population in a reactor must be known in order to determine the rate at which various neutron-nuclei interactions occur. For example, fission events are produced by neutron-fissile interaction and these events in turn produce more neutrons. The fission reactions also yield a large amount of energy (approximately 200 MeV for a neutron and U-235 fission reaction). Therefore, the fission events play an essential role both in propagating the chain reaction and also in producing the energy. Knowledge of the spatial and energy distribution of the neutron population is consequently needed to determine the spatial distribution of the energy production rate.