Image enhancement using MCNP5 code and MATLAB in neutron radiography

Image quality enhancement in Neutron Computerized Tomography based on projection exposure time adjustment

This paper presents a proposed procedure for neutron radiography image enhancement through studying the effect of the projection exposure time on the quality of Neutron Computerized Tomography (NCT) image. A sample was exposure at the Egyptian Second Research Reactor (ETRR-2) NCT facility with projection exposure time varying from one second to six seconds at reactor power operation of 17 MW_th. The NCT image was corrected against the read-out noise using flat and dark current images. Then, the Region of Interest (ROI) is selected based on an automatic threshold of the occurrence histogram of the image variance. After that, the image was normalized and filtered by median filter. The resultant images were evaluated qualitatively and compared with the images obtained from Octopus 8.5 software that is currently used in the Egyptian NCT facility. The results indicated that high-quality images had accomplished in comparison with Octopus 8.5 software without losing any information. In addition, with respect to quality measures, the image at the projection exposure time equal to 4 seconds is the best obtained image.

Designing a new graphite illuminator for imaging facility of INUS to improve neutron beam uniformity and intensity

A cylindrical graphite illuminator with a thickness of 6.5 cm and diameter of 18 cm was installed inside the collimator of INUS (Instalatie de Neutronografie UScata) neutron imaging facility in the past. The graphite illuminator is usually utilized inside the collimator of neutron imaging facility to provide an intense and approximately uniform beam of neutrons at the outlet of collimator. With the mentioned existing illuminator in INUS imaging facility, the thermal neutron flux at the exit of collimator was measured 7.2 × 10⁴ n/cm²/s. Also the obtained neutron beam profile in this facility shows that it is not completely uniform at the imaging screen and the intensity of neutrons at the top and bottom of beam profile are not the same. Hence, in this paper a new graphite illuminator is proposed to improve the neutron beam characteristics in INUS imaging facility. Monte Carlo N-Particle (MCNP) code was implemented in this study for evaluating the proposed illuminator. The shape of proposed illuminator is a cylinder whose one side is inclined. Three quality factors of thermal neutron intensity, thermal neutron beam uniformity and gamma radiation dose rate were used to evaluate performance of the new illuminator. In order to obtain optimum illuminator shape, three effective parameters of thickness, angle of inclined side and position of the illuminator inside the collimator were investigated in this research. The investigation was carried out on thicknesses in the range of 5 to 25 cm with a step of 5 cm, angles in the range of 10 to 60° with a step of 10° and positions of -5, 0 and 5 cm with respect to center of reactor core. After investigating and interpolating the results, it was found that the proposed illuminator with a thickness of 10 cm, angle of 54.5° and position of 0 can produce a uniform beam profile, increase the thermal neutron intensity up to 7.1% and also decrease the neutron to gamma ratio up to 5% in comparison with the existing one.