Real-time neutron radiography

The main objective of the present thesis was develop and get operational a real-time neutron radiography system, at the IPEN-CNEN/SP. This system is installed inside the shielding of an old facility, designed in 1988, for film radiography, which is installed at the beam-hole 08 of the 5 MW, IEA-R1 Nuclear Research Reactor. The most important modifications at the such facility were the increase of the γ-radiation filter thickness, increase of the inner area of the shielding, design of a neutron collimator and a light tight box. The main characteristics of the neutron beam at the irradiation position are: flux: 1 x 106n/cm2s, collimation ratio 70, effective energy 7 meV, diameter 20 cm, neutron/γ ratio ∼ 106n/cm2mrem. The real-time images have been obtained by means of an imaging system that consists of a screen scintillator, a light intensifier, a video camera, a digitizing frame grabber and a computer. The device composed by the scintillator and by the light intensifier is called LIXI (Light Intensifier X-ray Image). Improvements concerning image quality have been obtained by means of digital processing. The facility has been characterized in terms of its sensitivity for thickness discerning (Δx), and spatial resolution (Ut) and the obtained values were (Δx = 0.07 cm (LuciteTM) and Ut = 440 μm. These results were complemented by the modulation transfer function and, when compared with those from literature, they show that the present system's viability for inspection of both static and dynamic events. (author)