Design of a novel nondestructive portable mobile neutron activation system

A new non-destructive portable mobile system was designed to be used for neutron activation assay according to the Safeguards purposes. The sample is irradiated in a neutron field and its composition is determined by identifying the characteristic induced gamma radiation emitted by the fission and activation products. For the design of a neutron activation system, many aspects must be considered such as choosing the best materials to assure the protection against radiation and estimating the thickness required to shield the neutron source based on its flux or strength. The polyethylene and paraffin wax were selected as neutron shielding material, lead being chosen as gamma shielding material. Several calculations were performed using the Monte Carlo code MCNP5 to estimate the required shield thickness and distribution of thermal neutron flux at different irradiation position inside the shield. The available 252Cf neutron source with 12 µCi of activity was used. The novel neutron activation analysis system was proposed, designed and fabricated to meet the maximum flexibility for neutron activation analysis, at minimum cost and with adequate optimized shielding and portability.