Understanding Neutron Radiography

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2.3 <strong>Neutron</strong> Imaging ■ Collimation Ratio The collimation ratio is the ratio L·D -1 of the collimator length L to aperture diameter D. This ratio helps to predict image sharpness. ■ Imaging Processes For static thermal neutron radiography of nonradioactive objects, two important imaging processes are (1) the gadolinium converter with single emulsion X-ray film and (2) the neutron sensitive storage phosphor (neutron imaging plate). For static neutron radiography of radioactive objects, additional imaging processes are (1) dysprosium foil activation transfer to film, (2) indium foil activation transfer to film and (3) track etch imaging using a boron converter and cellulose nitrate film. Charlie Chong/ Fion Zhang
The established direct imaging technique uses thin gadolinium layer vapor deposited on a solid converter screen, which is held flat against a single emulsion film inside a vacuum cassette of thin aluminum construction. An exposure of 10 9 neutrons per square centimeter (10 9 n/cm 2 ) can give a high resolution, high contrast radiograph if careful dust free film darkroom procedures are used. <strong>Neutron</strong> sensitive imaging plates consist of a thin phosphor layer containing a mixture of storage phosphor, neutron converter and organic binder. Following the neutron exposure stage is the information readout phase, in which the plate is scanned by a thin laser beam stimulating the emission of a pattern of light. Merits of this neutron imaging technique include five decades of linearity (?) , wide dynamic range, direct availability of digital data for processing converter efficiencies of 30 to 40 percent, and spatial resolution acceptable for some applications. Charlie Chong/ Fion Zhang
Page 1 and 2: Understanding Neutron Radiography R
Page 3 and 4: Neutron Source-Cyclotron Charlie Ch
Page 5 and 6: Charlie Chong/ Fion Zhang
Page 7 and 8: 3. Techniques/Calibrations • Bloc
Page 11 and 12: Greek Alphabet Charlie Chong/ Fion
Page 15 and 16: Why Neutron Radiography? "finding l
Page 17 and 18: ■ http://minerals.usgs.gov/minera
Page 19 and 20: Screen Types-1 1. Transfer screen-i
Page 21 and 22: IVONA TTS Capable. Charlie Chong/ F
Page 23 and 24: Reading-1 ASNTHBVol4Chapter16 Charl
Page 25 and 26: FIGURE 1. Electric bridge wire squi
Page 27 and 28: FIGURE 1. Electric bridge wire squi
Page 29 and 30: FIGURE 2. Comparison of neutron rad
Page 31 and 32: User’s Guide Unlike many other fo
Page 33 and 34: PART 2. Static Radiography with The
Page 35 and 36: 2.2 Neutron Collimation Because the
Page 37 and 38: The source of thermal neutrons is a
Page 39 and 40: Parallel & Divergent Collimator - F
Page 41: 5.1 Neutron cross sections Neutron
Page 45 and 46: FIGURE 4. Neutron radiographs of nu
Page 47 and 48: FIGURE 4. Neutron radiographs of nu
Page 49 and 50: ASTM E803 - 91(2013) Standard Test
Page 51 and 52: FIGURE 5. Representative neutron ra
Page 53 and 54: Another reactor that has provided n
Page 55 and 56: FIGURE 7. Hot cell fuel inspection
Page 57 and 58: Hot cell Shielded nuclear radiation
Page 59 and 60: Applications: Hot cells are used to
Page 61 and 62: Hot Cell Charlie Chong/ Fion Zhang
Page 69 and 70: FIGURE 8. Cross section showing van
Page 71 and 72: FIGURE 9. Components of mobile deut
Page 73 and 74: FIGURE 10. Californium-252 sources
Page 75 and 76: FIGURE 11. Elevation of subcritical
Page 77 and 78: Californium-252 Neutron Source Char
Page 79 and 80: PART 3. Special Techniques of Neutr
Page 81 and 82: Other reactor centers have develope
Page 85 and 86: TABLE 2. Relative neutron attenuati
Page 87 and 88: FIGURE 14. Neutron radiographs of e
Page 89 and 90: The technique can provide high sens
Page 91 and 92: 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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Q50. The primary advantage of using
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More Reading- before going further!
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7. IMAGE RECORDERS The neutron radi
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7.1. PHOTOGRAPHIC FILM 7.1.1. Conve
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TABLE 7.1. Nuclear properties of ne
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TABLE 7.2. Transmittance and film d
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However, the shape of the curves fo
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7.1.4. Film contrast. In discussing
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Figure 7.1. Characteristic curve of
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The slope of a curve at a particula
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Figure 7.3. Characteristic curve of
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7.1.5. Film sensitivity (film speed
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TABLE 7.3. Approximate comparison o
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Figure 7.4. Typical signal-exposure
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Close inspection of the gadolinium
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TABLE 7.4. The characteristics of s
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To make an informed choice of imagi
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TADLE 7.5. Some characlcrislics of
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TADLE 7.8. Average exposure data fo
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where E is the electronic fluence c
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7.2. NITROCELLULOSE FILM 7.2.1. Fil
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In relation to thermal NR, the foll
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7.2.2. Film handling and safety pre
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Following recommendations and regul
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7.2.3. Exposure techniques and moun
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TABLE 7.9. Neutron fluences for nit
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The multifoil technique in fast NR
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The image generation in silver-hali
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Q51. Neutron beams used in nondestr
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Q56. High-resolution gadolinium con
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Q61. Which element is commonly used
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Q63. Lead is: a. a good neutron shi
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69. The emulsion side of a single-c
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72. Single-emulsion high-resolution
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77. Frilling 皱边 , 脱模 or l
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81. When manually processing films,
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85. Water spots on films can be min
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89. An advantage of the fountain-pe
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91. The average thermal neutron flu
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96. Overexposure to neutron or gamm
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100. The intensity of gamma rays is
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Q106. To achieve uniformity in neut
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TABLE 6. Properties of Some Thermal
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111. A main disadvantage of gadolin
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115. To an Operational Health Physi
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The neutrons transmitted through a
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Peach - 我爱桃子 Charlie Cho
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Good Luck Charlie Chong/ Fion Zhang
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Understanding Neutron Radiography

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