Abstract:
This paper presents the study on the
241Am-Be radionuclide sources reference neutron radiation field metrology characteristics for calibrating area neutron dose monitoring instruments. The Monte Carlo method was used to simulate the neutron ambient dose equivalent rate, scattering neutron proportion and neutron energy spectrum distribution at different points of test in the air free-field reference neutron radiation (FRNR), the minimum size of standard reference neutron radiation (SRNR) specified in GB/T 14055 series standards and the actual reference neutron radiation (ARNR). The results show that air has little effect on the dose rate and energy spectrum distribution in FRNR, which is approximately an ideal reference neutron radiation; the minimum size SRNR shielded by polyethylene containing 5% boron can decrease thermal neutrons and reduce the proportion of scattered neutrons. The shadow-cone method is not suitable for the correction of scattered neutrons in small-sized reference neutron radiation; scattering neutrons in ARNR are fewer and have a lower proportion, and the proportion of scattered neutrons obtained by shadow-cone method is basically consistent with the theoretical values.