Neutron localization technology can be used for monitoring spent fuel reprocessing to prevent nuclear criticality accidents.

This study aims to investigate the effects of different neutron emission modes, ³He pressure, tube diameter, and moderators on the position resolution and detection efficiency of a position-sensitive ³He proportional counter.

Firstly, a ³He proportional counter with a tube diameter, tube length, and ³He pressure of 2.54 cm, 80 cm, and 405 300 Pa, respectively, was taken as object of study, and the Monte Carlo (MC) algorithm was employed to simulate the effects of neutrons with different energies, neutron emission modes, ³He pressures, tube diameters, and moderating bodies on the position resolution and detection efficiency of a position-sensitive ³He proportional counter. Then, the effects of the time difference of arrival (TDOA) on the location of a source in an active zone, source to tube distances, thickness of moderating body, and position resolution of the ³He proportional counter were investigated. Finally, a linear fitting analysis of the active region was performed, and the locations of inactive regions were estimated to determine the positioning ability of the ³He tube.

Simulation results show that the position resolution of this ³He proportional counter is equal in all axial sections, and the position-resolution limit of thermal neutron source is 0.17 cm. When the thickness of the moderating body is 5 cm, and the ²⁴⁴Cm source is close to the external wall of the moderating body, the neutron detection efficiency is 3.0%, and the theoretical position resolution is 9.25 cm whilst experimental result of position resolution is 18.50 cm, half of the theoretical value, and the location resolution limit is 2.64 cm after processed by the linear fitting curve of the active location and a time-difference crest.

MC simulation and experimental tests show that the position-sensitive ³He proportional counter exhibits better position resolution and detection efficiency for the ²⁴⁴Cm source when the thickness of the moderating body is 2~3 cm, hence suitable for practical applications.