Understanding Neutron Radiography Reading III Rev.1A

1. Understanding Neutron R adiography R eading III R ev.1 My ASNT Level III, Pre-Exam Preparatory Self Study Notes 3 July 2015 Charlie Chong/ Fion Zhang

2. Nuclear Source- Plasma Fusion Charlie Chong/ Fion Zhang http://homework55.com/apphysicsb/ap5-28-08/

3. Nuclear Source- Plasma Fusion Charlie Chong/ Fion Zhang

4. Nuclear Source- Plasma Fusion 中国合肥核聚反应堆 Charlie Chong/ Fion Zhang http://iterchina.cn/

5. Nuclear Source- Plasma Fusion 中国合肥核聚反应堆 Charlie Chong/ Fion Zhang http://iterchina.cn/

6. Nuclear Source-Reactors Charlie Chong/ Fion Zhang http://iterchina.cn/

7. Nuclear Source-Reactors Charlie Chong/ Fion Zhang

8. Nuclear Source-Reactors Charlie Chong/ Fion Zhang http://homework55.com/apphysicsb/ap5-28-08/

9. The Magical Book of Neutron Radiography Charlie Chong/ Fion Zhang

10. 数字签名者：Fion Zhang DN：cn=Fion Zhang, o=Technical, ou=Academic, email=fion_zhang@ qq.com, c=CN 日期：2016.08.07 16:19:02 +08'00' Charlie Chong/ Fion Zhang

11. ASNT Certification Guide NDT Level III / PdM Level III NR - Neutron Radiographic Testing Length: 4 hours Questions: 135 1. Principles/Theory • Nature of penetrating radiation • Interaction between penetrating radiation and matter • Neutron radiography imaging • Radiometry 2. Equipment/Materials • Sources of neutrons • Radiation detectors • Non-imaging devices Charlie Chong/ Fion Zhang

12. 3. Techniques/Calibrations • Electron emission radiography • Blocking and filtering • Micro-radiography • Multifilm technique • Laminography (tomography) • Enlargement and projection • Control of diffraction effects • Stereoradiography • Panoramic exposures • Triangulation methods • Gaging • Autoradiography • Real time imaging • Flash Radiography • Image analysis techniques • In-motion radiography • Fluoroscopy Charlie Chong/ Fion Zhang

13. 4. Interpretation/Evaluation • Image-object relationships • Material considerations • Codes, standards, and specifications 5. Procedures • Imaging considerations • Film processing • Viewing of radiographs • Judging radiographic quality 6. Safety and Health • Exposure hazards • Methods of controlling radiation exposure • Operation and emergency procedures Reference Catalog Number NDT Handbook, Third Edition: Volume 4, Radiographic Testing 144 ASM Handbook Vol. 17, NDE and QC 105 Charlie Chong/ Fion Zhang

14. Charlie Chong/ Fion Zhang

15. Fion Zhang at Shanghai 3th July 2015 http://meilishouxihu.blog.163.com/ Charlie Chong/ Fion Zhang

16. Greek Alphabet Charlie Chong/ Fion Zhang

17. Charlie Chong/ Fion Zhang http://greekhouseoffonts.com/

18. Charlie Chong/ Fion Zhang

19. Why Neutron Radiography? "finding lead in a paraffin block (or a needle in a haystack) would work for x rays while looking for paraffin in a lead block or a straw in a needle-stack would work for neutrons." Charlie Chong/ Fion Zhang

20. Why Neutron Radiography? "finding lead in a paraffin block (or a needle in a haystack) would work for x rays while looking for paraffin in a lead block or a straw in a needle-stack would work for neutrons." Charlie Chong/ Fion Zhang

21. Why Neutron Radiography? "finding lead in a paraffin block (or a needle in a haystack) would work for x rays while looking for paraffin in a lead block or a straw in a needle-stack would work for neutrons." Charlie Chong/ Fion Zhang

22. ■ http://minerals.usgs.gov/minerals/pubs/commodity/ Charlie Chong/ Fion Zhang

23. Neutron Cross Section of the elements ■ http://periodictable.com/Properties/A/NeutronCrossSection.html Charlie Chong/ Fion Zhang

24. Screen Types-1 1. Transfer screen-indium or dysprosium, In, Dy, Gold, Silver, Rhodium, Europium, Samarium. 2. Thermal neutron filter using Cadmium for epithermal neutron radiography, Cd. Lithium resonance direct screen. 3. Converter screen uses gadolinium which emit beta particles, γ, conversion electron. 4. the beta particles are caught by a fluorescing zinc sulfide material 5. Scintillator screen: Zinc sulfide, Lithium carbonate, plastid scintillator, Gadolinium oxysulfide. 6. Accelerator (H+, 2H+)Target material: Beryllium, Be or lithium Li. 7. Boron used for neutron shields. Charlie Chong/ Fion Zhang

25. Screen Types-2 1. Beam filter, Beryllium thermalized thermal neutron further and pass only cold neutron. 2. Cadmium remove thermal & cold neutrons and pass epithermal neutrons. 3. Fast neutron direct radiography used Tantalum or transfer radiography with Holmium. 4. Gadolinium Gd, conversion screens emit- (1) gamma rays and (2) conversion electronn 5. Dysprosium (165m66Dy) conversion screens emit: (1) high-energy betas β, (2) low-energy gamma γ, and (3) internal-conversion electrons e-. Charlie Chong/ Fion Zhang

26. TABLE 6. Properties of Some Thermal Neutron Radiography Conversion Materials Material Useful Reactions Cross Section for Thermal Neutrons (barns) Life 6Li(n,α) 3H Lithium 910 prompt 10B(n,α) 7Li Boron 3,830 prompt 103Rh(n)104mRh Rhodium 11 45 min 103Rh(n)104Rh 139 42 s 107Ag(n)108Ag Silver 35 2.3 min 109Ag (n)110Ag 91 24 s 113Cd((n,γ)114Cd Cadmium 20,000 prompt 115In(n)116n Indium 157 54 min 115 In(n)116mln 42 14 s 149Sm(n,γ) 150Sm Samarium 41,000 prompt I52 Sm(n)153Sm 210 47 h 151Eu(n)152Eu Europium 3,000 9.2 h 155 Gd(n,γ) I56Gd Gadolinium 61,000 prompt 157 Gd(n,γ)158Gd 254,000 prompt 164 Dy(n)165mDy Dyprosium 2,200 1.25 min 164 Dy(n)165Dy 800 140 min 197Au(n)198Au Gold 99 2.7 days Charlie Chong/ Fion Zhang

27. The letter m is sometimes appended after the mass number to indicate a nuclear isomer, a metastable or energetically-excited nuclear state (as opposed to the lowest-energy ground state), for example 165mDy https://en.wikipedia.org/wiki/Isotope Charlie Chong/ Fion Zhang http://crete.homeip.net/show_nuclide/660465/

28. TABLE 6. Properties of Some Thermal Neutron Radiography Conversion Materials Charlie Chong/ Fion Zhang

29. IVONA TTS Capable. Charlie Chong/ Fion Zhang http://www.naturalreaders.com/

30. Reading III Content  Reading One: ASNTHBVol4Chapter16  Reading Two: Assorted  Reading Three: Neutron Radiography State of Art Report - NTIAC-SR-98-01  Reading Four: Charlie Chong/ Fion Zhang

31. Reading-1 ASNTHBVol4Chapter16 Charlie Chong/ Fion Zhang

32. PART 1. Applications of Neutron Radiography Neutron radiation is similar to X-radiation. The radiation can originate from an effective point source or can be collimated to shine through an object in a coherent beam. The pattern of penetrating radiation can then be studied to reveal clues about the internals of the object. The information conveyed can be very different from that obtainable with X-rays. Whereas X-rays are attenuated by dense metals more than by hydrocarbons, neutrons are attenuated more by hydrocarbons than by most metals. The difference can mean much more than the reversal of a positive image to a negative image. Neutrons, for example, can reveal details within high density surroundings that cannot be revealed by other means. A typical application for neutron radiography is shown in the images of a pyrotechnic device (Fig. 1), where the small explosive charge is encased in metal. Other applications include inspection of explosive cords used in pilot ejector mechanisms; inspection of gaskets, seals and O-rings inside metallic valves; confirmation that coolant channels in jet engine turbine blades are free of blockage; studies of coking in jet engine fuel nozzles; and screening of aircraft panels to detect low level moisture or early stage corrosion in aluminum honeycomb (Fig. 2). Charlie Chong/ Fion Zhang

33. FIGURE 1. Electric bridge wire squid: (a) drawing and (b) neutron radiograph of part as aid to interpretation; (c) helium-3 gaseous penetrant applied to serviceable unit; (d) penetrant applied to dysfunctional unit. Charlie Chong/ Fion Zhang

34. FIGURE 1. Electric bridge wire squid: (a) drawing and (b) neutron radiograph of part as aid to interpretation; (c) helium-3 gaseous penetrant applied to serviceable unit; (d) penetrant applied to dysfunctional unit. (b) Charlie Chong/ Fion Zhang

35. FIGURE 1. Electric bridge wire squid: (a) drawing and (b) neutron radiograph of part as aid to interpretation; (c) helium-3 gaseous penetrant applied to serviceable unit; (d) penetrant applied to dysfunctional unit. (c) Charlie Chong/ Fion Zhang

36. FIGURE 1. Electric bridge wire squid: (a) drawing and (b) neutron radiograph of part as aid to interpretation; (c) helium-3 gaseous penetrant applied to serviceable unit; (d) penetrant applied to dysfunctional unit. (d) Charlie Chong/ Fion Zhang

37. FIGURE 2. Comparison of neutron radiographs of moisture globules in aluminum honeycomb panel, later dried: (a) before processing; (b) after processing. (a) Charlie Chong/ Fion Zhang

38. FIGURE 2. Comparison of neutron radiographs of moisture globules in aluminum honeycomb panel, later dried: (a) before processing; (b) after processing. (b) Charlie Chong/ Fion Zhang

39. User’s Guide Unlike many other forms of nondestructive testing, neutron radiography is not a do-it-yourself technique. There have been neutron radiography service centers in the United States since 1968. To try out neutron radiography on an object of interest, it is simply necessary to locate the services currently available and, if agreed, mail your item to them. Typically, the neutron radiograph and your item will be mailed back within a day or two. The cost could be less than 1 or 2 h of an engineer’s time. If assistance is required to interpret the findings, this too may be requested on a service basis, as may referrals to more specialized neutron radiographic techniques. The providers of neutron radiography services use equipment and expertise that is highly specialized. Even though one or more neutron radiography service centers have been operating successfully for over 30 years, there has been no in- house neutron radiography available at any general service, commercial nondestructive testing center. Charlie Chong/ Fion Zhang

40. The interested user is therefore advised to seek a supplier of neutron radiographic services using leads such as society directories or the published literature. Because neutrons are fundamentally different from X-rays, any object that is a candidate for inspection by X- adiography could also be a candidate for neutron radiography. If X-rays cannot give sufficient information, then trials with neutron techniques may be prudent. The most frequently successful complement to X-radiography is static radiography with thermal neutrons. This approach is reviewed next. Then more specialized neutron radiology techniques are reviewed, such as neutron (1) computed tomography, (2) dynamic neutron imaging, (3) high frame rate neutron imaging, (4) neutron induced autoradiography and (5) neutron gaging. For each of the neutron radiology techniques different neutron energies may be selected. The user should be aware that many of the specialized services are only available at one or two centers worldwide. It is therefore important to shop in the global market and to take advantage of the excellent communications existing between neutron radiography centers in various countries. Charlie Chong/ Fion Zhang

41. PART 2. Static Radiography with Thermal Neutrons 2.1 Neutron Energy Thermal energy neutrons are those that have collided repeatedly with a moderator material, typically graphite or water (plastid, paraffin, graphite) , such that they reach an equilibrium energy with the thermal energy of the moderator nuclei. The attenuation coefficients for thermal neutrons differ from material to material in a way that is different from X-rays as shown in Table 1. As a consequence, a high degree of contrast between the elements in an object is possible. In addition, thermal neutrons are relatively easy to obtain and easy to detect. Keywords: Thermal Neutron: they reach an equilibrium energy with the thermal energy of the moderator nuclei. Charlie Chong/ Fion Zhang

42. TABLE 1. Comparison of X-ray and thermal neutron attenuation. a. Other materials relatively transparent to thermal neutrons include gold, silver, platinum, titanium, silicon, tin and zinc. b. Other materials relatively opaque to thermal neutrons include hydrogenous oils, plastics, rubbers, explosives and light elements boron and lithium. Charlie Chong/ Fion Zhang

43. TABLE 6. Properties of Some Thermal Neutron Radiography Conversion Materials Material Useful Reactions Cross Section for Thermal Neutrons (barns) Life 6Li(n,α) 3H Lithium 910 prompt 10B(n,α) 7Li Boron 3,830 prompt 103Rh(n)104mRh Rhodium 11 45 min 103Rh(n)104Rh 139 42 s 107Ag(n)108Ag Silver 35 2.3 min 109Ag (n)110Ag 91 24 s 113Cd((n,γ)114Cd Cadmium 20,000 prompt 115In(n)116n Indium 157 54 min 115 In(n)116mln 42 14 s 149Sm(n,γ) 150Sm Samarium 41,000 prompt I52 Sm(n)153Sm 210 47 h 151Eu(n)152Eu Europium 3,000 9.2 h 155 Gd(n,γ) I56Gd Gadolinium 61,000 prompt 157 Gd(n,γ)158Gd 254,000 prompt 164 Dy(n)165mDy Dyprosium 2,200 1.25 min 164 Dy(n)165Dy 800 140 min 197Au(n)198Au Gold 99 2.7 days Charlie Chong/ Fion Zhang

44. 2.2 Neutron Collimation Because the source of thermal neutrons is a dispersed moderator volume, rather than a point source, it is necessary to use a collimator between the source and the object. In preference to a (1) single tube parallel sided collimator or a (2) multiple slit (channels) collimator, the most frequently used design uses (3) divergent beam geometry. The collimator may be used to extract a beam in any one of a variety of different geometries including horizontal or vertical, radial or tangential to the source. A collimator that is tangential to the source can provide a thermal neutron beam relatively free of fast neutron and gamma ray contamination. An incidental consequence of the divergent collimator principal is that even very large objects can be radiographed using an array of side-by-side films (Fig. 3). Charlie Chong/ Fion Zhang

45. FIGURE 3. Radiographs of full size motorcycle: (a) neutron radiograph; (b) x- radiograph. Charlie Chong/ Fion Zhang

46. The source of thermal neutrons is a dispersed moderator volume, rather than a point source Charlie Chong/ Fion Zhang ASMV17 Neutron Radiography

47. Charlie Chong/ Fion Zhang ASMV17 Neutron Radiography

48. Parallel & Divergent Collimator - Fig. 2 Thermalization and collimation of beam in neutron radiography. Neutron collimators can be of the parallel-wall (a) or divergent (b) type. The transformation of fast neutrons to slow neutrons is achieved by moderator materials such as paraffin, water, graphite, heavy water, or beryllium. Boron is a typically used neutron-absorbing layer. The L/D ratio, where L is the total length from the inlet aperture to the detector (conversion screen) and D is the effective dimension of the inlet of the collimator, is a significant geometric factor that determines the angular divergence of the beam and the neutron intensity at the inspection plane Ug=D∙ t/L I = Ф/16∙(L/D)2 I = Ioe–μnt μn= N’σ N’ = nuclei/cm2 N’ = ρN/A N = Avogadro's number μn= N’σ = [ρN/A]∙σ Charlie Chong/ Fion Zhang ASMV17 Neutron Radiography

49. For photons: I = Ioe–μx t For Neutron I = Ioe–Nσt= Ioe–μn t Eq.1 Eq.2 Where:  I is the transmitted beam;  Iois the incident beam;  μxis the linear attenuation coefficient for photons;  t is the thickness of specimen in the beam path;  N is the number of atoms per cubic centimeter;  σ is the neutron cross section of the particular material or isotope (a probability or effective area); and,  μnis the linear attenuation coefficient for neutrons (μn= Nσ). Charlie Chong/ Fion Zhang

50. 5.1 Neutron cross sections Neutron cross sections are defined in Part 1 of this Section. Values for thermal neutrons for many materials (elements) are given in Table 9 (see Bibliography item 8 for a more extensive compilation). Generally, neutron cross sections decrease with increasing neutron energy; exceptions include resonances, as mentioned earlier. Cross section values can be used to calculate the attenuation coefficients and the neutron transmission as shown in eqs. 1 and 2. For compound inspection materials, the method for calculating the linear attenuation coeffici ent is shown following Table 9. If the material under inspection contains only one element, then the linear attenuation coefficient is: μ = ρ∙Nσ/ A Eq.7 (where ρ∙N/A is the number of nuclei/cm2) Where: μ -is the linear attenuation coefficient of specific neutron (cm-1) ; ρ is the material density (g/cm3); N is Avogadro's number (6.023 X 1023atoms/gram-molecular weight) ; σ is the total cross section in barns (cm2) ; and A is the gram atomic weight of material. Charlie Chong/ Fion Zhang