Estimation of Low Level Neutron Doses Based on Neutron Spectra in the Vicinity of a Nuclear Reactor

Abstract

For the improvement of dosimetric methods for low intensity neutrons, a highly sensitive multi-moderator neutron spectrometer was constructed and applied for the determination of neutron energy spectra in the vicinity of the Kinki University Reactor, UTR-KINKI. It became clear from the measured spectra that relatively high intensity fast neutrons were observed around the electrical connection panel of the reactor, while the 1/E neutrons and low intensity fast neutrons were usually observed in the vicinity of the nuclear reactor. These neutron energy spectra were obviously changed by the beam emission upward from the top shield of the reactor; especially, the intensity of low energy neutrons was very much increased by the interaction of neutrons with the ceiling of the reactor building. The neutron doses, which could not be precisely determined by a neutron sievert (Sv) counter, could be estimated on the basis of these neutron spectra.