Neutron radiography is a non-destructive technique for photographing the interior structure of solid objects. While radiography conceptually similar to conventional X-ray radiography, neutrons are attenuated by many light elements including hydrogen, boron and lithium but penetrate heavier materials such as metals: this is a direct contrast to X-rays, which are absorbed by heavier elements but cannot detect many lighter elements. Neutron and X-ray radiography are therefore considered complementary techniques for the visualization of the interior structures.

The Digital Neutron Radiography facility in MNR was first installed in April of 1989 under an NSERC grant, and a second-generation facility has now been constructed under a CFI grant at MNR’s beamport #3. This second generation three-dimension real time or high speed dynamic neutron radiography system is one of the few facilities in the world which can combine 2-dimensional neutron radiography images with a neutron scattering system to reconstruct 3-D real time (30 frame/sec) or high speed (2000 frame/sec) images. This system also can be combined with high-speed thermal infrared image (2-D image with 1000 frame/sec) or ultra high-speed ultrasonic tomography (micro-second order) for more accurate and faster reconstruction of 3-D dynamic images. A schematic representation of this facility is shown in the Figure below.

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Fig. 1 Schematics of 3-D Dynamic Neutron Radiography System

Typical applications of neutron radiography include the testing of nuclear reactor fuel, detecting of hydrogenous materials, detecting flaws in gas turbine blades and corrosion of aircraft components. It can also be used for quality control of ceramics, detection of explosive charges, and detection of the presence of lubrication films inside gear boxes or bearings. Current research projects include environmental and energy technology developments including testing diesel particulate filters, diesel exhaust gas re-circulation system heat exchangers (Fig.2.), and thermal regeneration ceramic elements to name a few.

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Fig.2 Typical Diesel Exhaust Gas Recirculation Heat Exchanger (Photograph Front View and RTNR Image Side View)

Contributed by by J.S. Chang, G.D. Harvel, C.Y. Ching, J.S. Cotton, Department of Engineering Physics and Department of Mechanical Engineering, McMaster University

For more information regarding Neutron Radiography and MNR please contact N-Ray Services Inc..