Improvements in the Image Quality of Neutron Radiograms of NUR Neutron Radiography Facility by Using Several Exposure Techniques


Since the construction of NUR reactor neutron radiography facility in 1991, only transfer exposure methodwas used as a non destructive technique. The reason is the excess of gamma rays in the neutron beam. To improveradiation performances of the NR system, a stainless steal hollow conical cylinder is introduced at the bottom of thefacility beam port, this filter reduce gamma infiltration through the edges of the NR structure without disturbing neutronbeam arriving from the in pool divergent collimator. First results confmn our prediction; a gamma rays diminution and arelatively stable neutron flux at the point object are confmned, consequently the n/y ratio reaches a value of 2.104 n/cm2mR. Radiograms obtained by using the direct exposure method reveal the feasibility of the technique in the new NRconfiguration facility, but a weak resolution and contrast of the image is observed. In this paper, we describe a procedureto improve the image quality obtained by direct exposure technique. The process consists of using digitized imagesobtained by several exposure techniques (NR, gamma radiography or X radiography) for a comparison study and thenbetter image defmition can be attained.Keywords: neutron radiography, direct exposure technique, image quality, gamma raysPACS: 07.05.Rm, 81.70.-q. T. Zergoug~, A. Nedjarl, M.Y. Mokeddeml, L. MammoulCentre de Recherche Nucleaire de Draria, (CRND) BP 43 Draria 16000, Algiers, Algeria