Design and optimization of a source (reflector/shielding) performance test system based on (241Am-Be)-paraffin thermal neutron irradiation device

Journal Article

2025

Laboratory measurements and Monte Carlo simulations were conducted to investigate the feasibility of
employing a (reflector/shield) to improve the efficiency of a thermal neutron irradiator utilizing a paraffinmoderated
single 241Am-Be source with an activity of 1 Ci. A multi-parameter optimization was performed to
evaluate the potential of natural lead (Pb) and 90 % enriched 208Pb lead (208Pb(90 %)) in terms of increasing the
neutron production while minimizing the total dose equivalent rate. The laboratory-derived optimal configuration
for the (reflector/shield) assembly demonstrated that Pb significantly increased the neutron flux by
approximately 58 % and reduced the total dose equivalent rate to 0.00443 mSv/h, thereby allowing for a
workload of 4500 h within the annual permissible dose limit of 20 mSv. The MCNP simulations validated the
potentials of Pb and confirmed the superiority of 208Pb(90 %) in terms of increasing neutron flux to about 26 %
compared to that measured for Pb, while also minimizing the total dose equivalent rate to 0.0037 mSv/h. Thus,
enabling a workload of approximately 5400 h, which is higher by about 20 % compared to that permitted by Pb
based on measurements. The geometrical configuration and results promoted the use of the proposed TNI device
primarily for prompt gamma neutron activation analysis (PGNAA).

• Publication Work Type: ورقة علمية