Performance of 10B+ZnS(Ag) neutron detectors in RPM for the detection of special nuclear materials

摘要

AbstractIn homeland security, neutron detection is used to prevent the smuggling of Special Nuclear Materials in the fight against nuclear terrorism. Thermal neutrons are normally detected with3He proportional counters surrounded by a polyethylene box. However, due to the3He shortage in the radiation portal monitors reported in 2009, new procedures are being studied. In this work, Monte Carlo methods (using the MCNP6 code) have been used to study the neutron detection features of a10B?+?ZnS(Ag) under real conditions inside a radiation portal monitor. The performance of neutron detection was carried out for252Cf, HEU235U (enriched at 70% and 94%) and239Pu (enriched at 93%) under two different conditions, bare and shielded with lead and polyethylene. To mimic an actual situation occurring at border areas, when a vehicle was passing through the detection zone, a sample of Special Nuclear Materials, SNM, sited inside a cargo vehicle mixed with scrap was simulated, and the radiation portal monitors contained10B?+?ZnS(Ag) neutron detectors. The responses were calculated for four different neutron detectors, two real detectors (N-15 and N-48) and two prototype detectors (N-15 plus and N-48 plus), which are based on the N-15 and N-48 geometries with an improvement in the amount of10B and a higher polymethyl methacrylate, PMMA, thickness. Measurements were reported for the actuals detectors, and the response was greater than 200?cm from a neutron source of