| ABSTRACT: | THE DESIGN OF NEUTRON RADIOGRAPHY FACILITY AND ITS APPLICATION IN SPRR-
300
B. Tang, S. Zhang, M. Xia, and S. Zhu
Institute of Nuclear Physics and Chemistry, CAEP, Mianyang, China
The neutron radiography is one of nondestructive test technologies. The neutron radiography facility has
been designed in SPRR (Swimming Pool Research Reactor) -300 to check the inner structure of some
components. The facility is made up of collimator system, the table for sample, the imaging system, the
controlling system and so on. In the collimator system, graphite is used as moderator, and bismuth as
gamma filter and the material made of lead, boron, polyethylene and cadmium as the diaphragm. The
interior structure of the collimator is like a labyrinth in order to reduce its weight and absorb effectively
scattered neutrons. For improving the shielding performance and the controlling precision of the exposure
time, a shutter is used. The table for sample is used to modify the tested part and orientation of the sample.
There are two methods of neutron radiography, one using films (including direct imaging and indirect
imaging) and the other using twilight CCD camera. The converters are Gd foil and Gd2O2S foil for direct
imaging, and In foil, Dy foil for indirect imaging, and NNU-2(6LiFZnS(Ag)) for CCD imaging. To improve
Signal-to-Noise in CCD imaging system, the double thermocouple refrigeration is used. To improve
resolution power, the lens with small visual angle is used. To improve dynamic range, the image grabbing,
processing and analyzing technology of 14bit gray is used. In the controlling system, PLC(Programmable
Logic Control) is used to improve the facility automation and the radiation shielding of researchers and
instruments.
The neutron radiography has been utilized in recent years to detect internal structures or defects of some
components in SPRR-300, and some good effects were obtained.
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