Understanding Neutron Radiography

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Charlie Chong/ Fion Zhang
Radioactive Objects An additional advantage of neutron radiography is its ability to radiograph specimens that are intense sources of photons (radioactive specimens). 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. Atomic nuclei in the metal screen absorb neutrons to produce short-lived radioactive isotopes. After removal from the neutron beam, the decay of radioisotopes in the screen exposes a film, giving an autoradiograph of the specimen. 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 37: Charlie Chong/ Fion Zhang
Page 41 and 42: lmaging Neutron radiographs usually
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
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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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Source of Neutrons-Beta Decay Decay
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Source of Neutrons 236 U 92 ? Charl
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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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