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The performance of neutron tomography facility at the Thai Research Reactor TRR-1/M1 is studied. Thermal neutron beams with a flux of 106 n/cm2/s are employed to radiate on a standard sample, so-called Strip B, in the test. The neutron irradiating on samples were detected by a neutron-to-photon conversion plate. After that, the low-energy photons were guided to a charge coupled device (CCD) to obtain a digital image. During the experiment, a rotation stage was used to rotate the sample in order to measure the attenuated/scatted neutrons at different angles with respect to the sample geometry. The angle-varied images were then processed via a reconstruction software to create a 3-dimension (3D) image (tomography). The result shows that an image of 0.5 mm-diameter cadmium wire could be observed by employing our facility, but the sharpness of the 3D image is still needed to be further improved.

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The neutron imaging facility at Thai Research Reactor-1/Modification 1 (TRR-1/M1), located at Thailand Institute of Nuclear Technology (Public Organization) has been improved for non-destructive characterization of internal structure of materials. The aims are to study the beam characteristic after an installation of the external collimator, and to optimize the exposure condition for a new setup. The neutron imaging setup was modified to increase the L/D ratio. As a consequence of the extended distance from the beam port to the sample position, an external collimator was installed to focus the neutron beam since 2018. Moreover, a new sample holder was installed to support sample rotation and translations with increased stability. The experiment was performed at the TRR-1/M1 reactor with 1 MW-reactor power. The neutron beam at the 8-inches south beam port of the TRR-1/M1 was evaluated in terms of beam homogeneity and the relationship between the grayscale value and image quality obtained from a CCD camera. The present performance of the neutron imaging system was tested with an ASTM standard sample, called sensitivity indicator. The results are shown in terms of image contrast and sharpness.