Understanding Neutron Radiography

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The neutrons transmitted through a radioactive specimen will strike a metal detection foil such as indium, dysprosium or gold, rather than a converter screen with film. Charlie Chong/ Fion Zhang
lmaging <strong>Neutron</strong> radiographs usually are recorded on conventional X-ray film . Although neutrons have little direct effect on film, many techniques have been devised to convert neutrons into radiations that will expose a film or produce light for a real-time imaging system. These converter screens are similar to the intensifying screens used in photon radiography. Disadvantages Disadvantages of neutron radiography include (1) the high cost of the sources, (2) the relatively large size of the most practical neutron source assemblies, and (3) the personnel protection and safeguard problems associated with neutrons. These disadvantages combine to yield a major limitation of the technique; no really portable, inexpensive system is available. Nevertheless, equipment to produce neutron radiographs is available; in special circumstances, the unique information provided by neutron radiography outweighs the disadvantages. Charlie Chong/ Fion Zhang
Page 1 and 2: Understanding Neutron Radiography R
Page 3 and 4: Military Applications Charlie Chong
Page 5 and 6: Military Applications Charlie Chong
Page 7 and 8: Charlie Chong/ Fion Zhang
Page 9 and 10: 3. Techniques/Calibrations • Bloc
Page 13 and 14: Greek Alphabet Charlie Chong/ Fion
Page 17 and 18: Reading I SECTION 12-Neutron Radiog
Page 19 and 20: The text includes helpful discussio
Page 21 and 22: PART 1 PRINCIPLES OF NEUTRON RADIOG
Page 23 and 24: Advantages lt is the differences be
Page 25 and 26: For photons: I = I o e -μx t For N
Page 27 and 28: Figure 1 provides a comparison of t
Page 29 and 30: FIGURE 1. Mass Attenuation Coeffici
Page 33 and 34: Neutron Radiography There is a mark
Page 35 and 36: hydrogen/boron beryllium/ water cad
Page 39: Radioactive Objects An additional a
Page 43 and 44: PART 2 EQUIPMENT AND PROCEDURES Cha
Page 45 and 46: ■ Fission When a neutron enters a
Page 47 and 48: U-235 and Pu-239. Charlie Chong/ Fi
Page 49 and 50: U-235 and Pu-239. Charlie Chong/ Fi
Page 51 and 52: Alpha Particles Charlie Chong/ Fion
Page 53 and 54: Alpha Particles Charlie Chong/ Fion
Page 55 and 56: Photoneutrons The necessary energy
Page 57 and 58: Radioactive Decay Charlie Chong/ Fi
Page 59 and 60: 2.2 Neutron Energies As with all pe
Page 61 and 62: Thermal Neutrons “Produced by slo
Page 63 and 64: There are applications in which the
Page 65 and 66: FIGURE 2. Neutron Radiographs of Hi
Page 67 and 68: Fast Neutrons “Fast neutrons prov
Page 69 and 70: Moderators A complete description o
Page 71 and 72: TABLE 2. Slowing Down Properties of
Page 73 and 74: TABLE 3. Some Thermallzatlon Factor
Page 75 and 76: 2.4 Neutron Collimation Beam extrac
Page 77 and 78: FIGURE 4. Neutron Collimators: (a)
Page 79 and 80: Divergent Collimators The primary a
Page 81 and 82: As in X- radiography, the geometric
Page 83 and 84: Geometric Unsharpness (neutron radi
Page 85 and 86: I ≈ Ф 16(L/D) 2 for my ASNT exam
Page 87 and 88: Backscatter It is good practice to
Page 89 and 90: TABLE 4. Average Characteristics of
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Nuclear Reactor The majority of pra
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Accelerators Numerous nuclear react
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(d.T) Source A reaction that has re
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Nuclear physicist at the Idaho Nati
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The gas pressure in the ion source
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(X.n) Sources Electron accelerators
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The threshold energy for photoneutr
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Bremsstrahlung , from bremsen "to b
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Characteristic x-rays are emitted f
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The frequencies of the characterist
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"Bremsstrahlung" means "braking rad
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Bohr’s Model Charlie Chong/ Fion
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Bohr’s Model Charlie Chong/ Fion
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Electron Orbital Charlie Chong/ Fio
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Plasma Sources Radiography with fas
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TABLE 5. Some Radloaalve Sources fo
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TABLE 5. Some Radloaalve Sources fo
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■ (γ,n) Sources The (γ,n) react
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■ Cf-252 On the basis of technica
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Subcritical Flux Boosters By defint
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Neutron Intensity Very few, if any,
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Beam Tailoring A neutron beam extra
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Foil Filters Some materials have sp
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■ Window Filters For some element
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Fig.14-5 The neutron yield strongly
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■ Time of Flight It is possible t
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2.7 Neutron Image Detectors All the
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FIGURE 5. Diagrams for Neutron Radi
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TABLE 6. Properties of Some Thermal
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■ Transfer Method In the transfer
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Transfer Method Examples Transfer r
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■ Exposures, Contrast, Resolution
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■ Reciprocity-Law Failure Scintil
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■ Neutron-Gamma Response One impo
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■ Real-Time Neutron Image Detecti
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■ Other Detectors for Thermal Neu
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■ Track-Etch Results The track-et
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1) Epithermal Neutrons Work with ne
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3) Fast Neutrons The other energy r
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As an example, copper screens are o
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■ Detector Discussion Image detec
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3.1 General General applications fo
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FIGURE 6. Radiographs of Explosive
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FIGURE 7. Thermal Neutron Radiograp
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3.8 Nuclear Industry Nuclear applic
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PART 4 NEUTRON RADIOGRAPHY STANDARD
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4.2 System Performance Standards St
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Those sources of radiation subject
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■ Personnel Protection All NRC li
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5.1 Neutron cross sections Neutron
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TABLE 9. Thermal Neutron Linear Att
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As an example, consider the calcula
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FIGURE 10. Half-Value Layers of Sel
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FIGURE 11. Tenth-Value Layers of Se
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5.3 Tenth-Value Layers There will b
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End Of Reading Charlie Chong/ Fion
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Source of Neutrons Charlie Chong/ F
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Radioactive Decay Interactive http:
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Charlie Chong/ Fion Zhang
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Source of Neutrons-Beta Decay Decay
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Source of Neutrons 236 U 92 ? Charl
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Charlie Chong/ Fion Zhang
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Radioactive Decay Charlie Chong/ Fi
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http://periodictable.com/Isotopes/0
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Neutron Energy & Detectability Slow
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Neutron Energy & Detectability Slow
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■ωσμ∙Ωπ∆º≠δ≤>ηθ
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Good Luck Charlie Chong/ Fion Zhang
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Understanding Neutron Radiography

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