Understanding Neutron Radiography

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7.3. COMPARISON BETWEEN SILVER-HALIDE AND NITROCELLULOSE FILM WITH REGARD TO IMAGE RECORDING AND QUALITY The image generation in nitrocellulose film is based upon the n/alpha reaction or on heavy particles (protons). Each particle creates in the film a defect (track) in function of its energy. The accumulated tracks form the image. The image density and sharpness depend primarily on the neutron fluence. The image quality depends thereafter on the processing (etching), which is sensitive to the temperature and concentration of the etching bath and etching duration. The etching process will increase the size of each track, it will form a conical hole with increased depth. With progressive etching, the tracks will interconnect and lead to erosion of the film surface. Finally the film will become foggy and lose contrast. Charlie Chong/ Fion Zhang Practical.NR Chapter 7
The image generation in silver-halide film in NR is based on ionisation by electrons (beta particles) or gamma-rays which interact along their passage through the emulsion with several silver-halide crystals and triggers their conversion to metallic silver. This results in a less pointlike image generation than with nitrocellulose film. The sharpness of the image is therefore determined by the grain size of the film. Its density depends also on the neutron fluence. The efficiency of the nitrocellulose film depends on the type of converter. Nitrocellulose film with integral converter (Kodak CN 85 B) is approx. twice as fast in terms of exposure time as the system using Dysprosium foil and a fine grain silver-halide film (Kodak SR). Charlie Chong/ Fion Zhang Practical.NR Chapter 7
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Understanding Neutron Radiography R
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Neutron Source-Cyclotron Charlie Ch
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Charlie Chong/ Fion Zhang
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3. Techniques/Calibrations • Bloc
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Greek Alphabet Charlie Chong/ Fion
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Why Neutron Radiography? "finding l
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Screen Types-1 1. Transfer screen-i
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FIGURE 1. Electric bridge wire squi
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FIGURE 1. Electric bridge wire squi
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FIGURE 2. Comparison of neutron rad
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User’s Guide Unlike many other fo
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PART 2. Static Radiography with The
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2.2 Neutron Collimation Because the
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The source of thermal neutrons is a
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Parallel & Divergent Collimator - F
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5.1 Neutron cross sections Neutron
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The established direct imaging tech
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FIGURE 4. Neutron radiographs of nu
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FIGURE 4. Neutron radiographs of nu
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ASTM E803 - 91(2013) Standard Test
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FIGURE 5. Representative neutron ra
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Another reactor that has provided n
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FIGURE 7. Hot cell fuel inspection
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Hot cell Shielded nuclear radiation
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Applications: Hot cells are used to
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Hot Cell Charlie Chong/ Fion Zhang
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FIGURE 8. Cross section showing van
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FIGURE 9. Components of mobile deut
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FIGURE 10. Californium-252 sources
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FIGURE 11. Elevation of subcritical
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Californium-252 Neutron Source Char
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PART 3. Special Techniques of Neutr
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Other reactor centers have develope
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TABLE 2. Relative neutron attenuati
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FIGURE 14. Neutron radiographs of e
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The technique can provide high sens
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3.5 Neutron Gaging and Neutron Prob
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3.6 Closing Industry standards have
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Reading-2 ASNTNRTMQA123 Level-I Cha
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Level 1 Answers Neutron Radiographi
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Q1. Neutron penetration is greatest
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Q6. Many of the absorption differen
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Q11. Gadolinium conversion screens
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The neutrons transmitted through a
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Q20. For inspection of radioactive
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Q24. A graph showing the relationsh
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Q30. Which of the following materia
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Q34. Movement, geometry, and screen
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Q39. An Image Quality Indicator is
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TABLE 6. Properties of Some Thermal
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Charlie Chong/ Fion Zhang Practical
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Q45. In the converter screen techni
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Charlie Chong/ Fion Zhang Practical
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Q50. The primary advantage of using
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Page 129 and 130: 7. IMAGE RECORDERS The neutron radi
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Page 189 and 190: Q63. Lead is: a. a good neutron shi
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Page 219 and 220: Peach - 我爱桃子 Charlie Cho
Page 221 and 222: Good Luck Charlie Chong/ Fion Zhang
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Understanding Neutron Radiography

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