Since 1985 the Argonauta Reactor at the Instituto de Engenharia Nuclear - IEN/CNEN has been used as a source of thermal neutrons to acquire transmission-generated radiographic images. From that time until the end of the last century, some Universities and Research Institutions have as well used the irradiation facilities of this reactor for that purpose and for technical and scientific training of personnel. Quite recently, a joint work program with the Laboratório de Instrumentação Nuclear - LIN/COPPE-UFRJ has been initiated addressing the research in the field of radiographic images using thermal neutrons, with special emphasis on Computer Aided Tomography. Within this frame, different tomographic systems - each one with their intrinsic features - have been developed aiming at their use in the industry field which requires the inspection of objects exhibiting different sizes and compositions. This work focuses the developed tomographs presenting their constraints and performances such as Spatial Resolution, Modulation Transfer Function and Density Resolution. The acquired images of some objects and test-bodies are as well presented for the sake of qualitative evaluation. They show a fair agreement with the performance of the tomographic system as expected from the measured quantitative parameters.
