Determination of neutron image quality of compact collimator facility for non-destructive testing

Abstract

Neutron imaging, based on a digital-based detector system, was developed for non-destructive internal inspection at the Thai Research Reactor-1/Modification 1 (TRR-1/M1). Neutron activation analysis was employed to determine thermal-neutron flux at the imaging position. The facility provided flux of thermal neutrons at 2.5× 10⁵ cm⁻²s⁻¹. Several standard samples were used to evaluate the collimation ratio (L/D), resolution, and unsharpness for the current setup of neutron imaging. An analytical method was employed to determine image quality parameters to moderate neutron flux. The L/D ratio depends on the aperture size of the divergent collimator and can be amended by using appropriate sample shape, resulting in more accurate estimate of collimation parameters. Resolution and unsharpness for neutron tomography were 0.5 mm and 1 mm, respectively. Results suggested the possibility of evaluating image quality using samples with non-complex structure.