In this paper,the equivalent radius of radioactive sources in each segment is determined by analyzing the different responses of the two identical detectors,and an improved segmented gamma scanning is used to assay waste drums containing mainly organic materials,and proved by an established simulation model.The simulated radioactivity distributions in homogenous waste drum and an experimental heterogeneous waste drum were compared with those of traditional segmented gamma scanning.The results show that our method is good in performance and can be used for analyzing the waste drums.
The response of a 14 MeV neutron-based prompt gamma neutron activation analysis (PGNAA) system,i.e.the prompt gamma-rays count rate and the average thermal neutron flux,is studied with a large concrete sample and with a homogeneous large sample,which is made of polyethylene and metal with various concentrations of hydrogen and cadmium using the MCNP-5 (Monte Carlo N-Particle) code.The average thermal neutron flux is determined by the analysis of the prompt gamma-rays using the thermal neutron activation of hydrogen in the sample,and the thermal and fast neutron activation of carbon graphite irradiation chamber of the PGNAA-system.Our results demonstrated that the graphite irradiation chamber of the PGNAA-system fairly operates,and is useful to estimate the average thermal neutron flux of large samples with various compositions irradiated by 14 MeV neutrons.
