Source substitution and optimization of CBX^TM PGNAA analyzer in Kangan cement plant

Highlights: •A detailed model of CBX prompt gamma neutron activation analyzer for MCNP. •Detailed calculation of source shielding for neutrons and gammas. •Detailed evaluation of the optimum moderator for highest thermal neutron production. •Detailed evaluation of ²⁵²Cf neutron source substitution with AmBe neutron source. •Comparison of the neutron and gamma fluxes at the detector for both sources of ²⁵²Cf and AmBe. -- Abstract: Prompt Gamma Neutron Activation Analysis (PGNAA) is a powerful nondestructive, elemental analysis tool that make use of the time-based characteristics of a nuclear reaction to enhance the capability for multi-elemental analyses. In the present study, improving the moderator and gamma radiation shield of a CBX^™ PGNAA analyzer system in Kangan cement factory, as well as substituting a longer half-life neutron source are investigated by utilizing Monte Carlo simulations. The results of the Monte Carlo simulations indicate that high density polyethylene (HDPE) with a thickness of 5 cm as the moderator and lead with a thickness of 4 cm as the gamma radiation shield are the best alternatives for the intended purposes. The long half-life (∼433 years) of AmBe would provide an almost constant level of neutron source over the lifetime of the equipment (∼20 years) and could be substituted for ²⁵²Cf (T_1/2 = 2.65 years) as neutron source. Meanwhile AmBe has higher prompt gamma yield than original source which makes it more suitable for PGNAA. Without much complications, the improved system could be implemented in the original CBX^™ PGNAA system.