Understanding Neutron Radiography Reading IV-Part1

Understanding Neutron RadiographyReading IV-Level1,2&3•ExerciseMy ASNT Level III, Pre-Exam Preparatory Self Study Notes 7 July 2015

Charlie Chong/ Fion Zhang

Nuclear Source-Reactors



Neutron Source-Reactor

http://opasnajazona.blogspot.com/2012/02/visiting-nuclear-research-reactor.html






http://opasnajazona.blogspot.com/2012/02/visiting-nuclear-research-reactor.htmlhttp://radiationcenter.oregonstate.edu/content/oregon-state-triga-reactor-0?quicktabs_1=2


Neu

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Neutron moderator


■ https://www.youtube.com/embed/kss2aaQKLSo?feature=player_detailpage


Nuclear Reactor - Understanding how it works | Physics Elearning


■ https://www.youtube.com/watch?v=1U6Nzcv9Vws

The Magical Book of Neutron Radiography




ASNT Certification GuideNDT Level III / PdM Level IIINR - Neutron Radiographic TestingLength: 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


• Electron emission radiography• Micro-radiography• Laminography (tomography)• Control of diffraction effects• Panoramic exposures• Gaging• Real time imaging• Image analysis techniques

3. Techniques/Calibrations• Blocking and filtering• Multifilm technique• Enlargement and projection• Stereoradiography• Triangulation methods• Autoradiography• Flash Radiography• In-motion radiography• Fluoroscopy


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 NumberNDT Handbook, Third Edition: Volume 4,Radiographic Testing 144ASM Handbook Vol. 17, NDE and QC 105


Fion Zhang at Shanghai7th July 2015

http://meilishouxihu.blog.163.com/


Greek Alphabet


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



■ http://minerals.usgs.gov/minerals/pubs/commodity/


Neutron Cross Section of the elements

■ http://periodictable.com/Properties/A/NeutronCrossSection.html


Neutron Cross Section of the elements

■ http://www.ncnr.nist.gov/resources/n-lengths/


Mass Attenuation Coefficient Against Atomic Number.


FIG. X1.1 Approximate Mass Attenuation Coefficients as a Function of Atomic Number

Atomic Number

Designation: E 748 – 02


Screen Types-11. Transfer screen-indium or dysprosium, In, Dy.2. Thermal neutron filter using Cadmium for epithermal neutron radiography,

Cd.3. Converter screen uses gadolinium which emit beta particles, Gd.4. the beta particles are caught by a fluorescing zinc sulfide material5. Scintillator screen: Zinc sulfide, Lithium carbonate, plastid scintillator6. Neutron Accelerator Target material: Beryllium, Be.7. Boron used for neutron shields.8. Transfer screen-indium or dysprosium, In, Dy.9. Thermal neutron filter using Cadmium for epithermal neutron radiography,

Cd.


Screen Types-28. Converter screen uses gadolinium which emit beta particles (conversion

electron or β particle?), Gd.9. the beta particles are caught by a fluorescing zinc sulfide material10. Scintillator screen: Zinc sulfide, Lithium carbonate, plastid scintillator

(cellulose nitrate film)11. Neutron Accelerator Target material: Beryllium, Be.12. Beam filter, Beryllium thermalized thermal neutron further and pass only

cold neutron.13. Cadmium remove thermal & cold neutrons and pass epithermal neutrons.14. Fast neutron direct radiography used Tantalum or transfer radiography

with Holmium.15. Gadolinium Gd, conversion screens emit- (1) gamma rays and (2)

conversion electronn16. Dysprosium (161

66Dy) conversion screens emit: (1) high-energy betas β, (2) low-energy gammas γ, and (3) internal-conversion electrons e.


TABLE 7.4. The characteristics of some possible neutron radiography converter materials

Practical.NR Table 7.4

Charlie Chong/ Fion Zhang Practical.NR Table 7.4


Internal-conversion Electrons


IVONA TTS Capable.

http://www.naturalreaders.com/


Reading IVContent Reading One: ASNTNRTMQ123 Reading Two: Reading Three: Reading Four:


Reading-One atASNTNRTMQA123Level-I

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Level 1 QuestionsNeutron Radiographic Testing Method


Level 1 AnswersNeutron Radiographic Testing Method


Level 1 AnswersNeutron Radiographic Testing Method


Q1. Neutron penetration is greatest in which of the following materials?a. hydrogenous materialb. waterc. leadd. boron carbide

Q2. In general, by increasing the neutron energy from a neutron radiographic source:a. greater neutron penetration is achievedb. greater neutron radiographic contrast can be obtainedc. radiographic exposure time can be reducedd. resolution can be increased

Q3. The time required for one-half of the atoms in a particular sample of radioactive material to disintegrate is called:a. the inverse square lawb. a curiec. a half-lifed. the exposure time


Q4. Generally, the attenuation of neutrons by a given material is:a. reported to the Atomic Energy Commissionb. greater for fast neutrons than thermal neutronsc. an indication of the quality of the X-radiographic techniqued. appreciably greater for thermal and epithermal neutrons than for fast neutrons

Q5. The mass absorption coefficients for thermal neutrons when plotted against regularly increasing atomic numbers of periodic elements presents a:a. blurred pictureb. regularly increasing picturec. random pictured. dark picture


Q6. Many of the absorption differences between neutrons and X-rays indicate clearly that the two techniques:a. cause radiation problemsb. complement each otherc. increase exposure speedd. fog radiographic film

Q7. The neutron cross section is the term normally used to denote:a. the danger in handling radioactive materialb. the absorbing power of a material for neutronsc. the atomic number of neutron reactor materiald. radiation detection equipment

Q8. The sharpness of the outline in the image of the radiograph is a measure of:a. subject contrastb. radiographic definitionc. radiographic contrastd. film contrast


Q9. The highest quality direct neutron radiographs obtainable today use:a. imaging screens using lithium-zinc sulfide as the imaging materialsb. high-speed radiographic filmsc. dysprosium as an imaging screend. gadolinium as an imaging screen (?)

Q10. When doing neutron radiography on radioactive materials, the materials are best handled:a. directly by personnel equipped with special protective clothingb. by remote handling equipmentc. directly by personnel with special protective clothing except when radiographs are being maded. by the same methods used for nonradioactive materials


Q11. Gadolinium conversion screens are usually mounted in rigid holders called: (direct radiography?)a. film racksb. cassettesc. emulsifiersd. diaphragms

Q12. The best high-intensity source of thermal neutrons is:a. a Cf-252 sourceb. an acceleratorc. a nuclear reactord. a Cf-252 source plus a multiplier

Q13. Scattered radiation caused by any material, such as a wall or floor, on the film side of the specimen is referred to as:a. primary scatteringb. undercutc. reflected scatteringd. back-scattered radiation


Q14. What has the highest thermal neutron absorption cross section?a. goldb. Indiumc. gadoliniumd. dysprosium

Q15. Conversion screens are used in neutron radiography:a. to convert neutron energy into ionizing radiationb. to increase the exposure timec. both a and b are reasons for using conversion screensd. neither a nor b is a reason for using conversion screens

Q16. A curie is the equivalent of:a. 0.001 mCib. 1000 mCic. 1000 MCid. 100 MCi


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.


FIG. X1.1 Approximate Mass Attenuation Coefficients as a Function of Atomic Number

Atomic Number

Designation: E 748 – 02


Q17. Short wavelength electromagnetic radiation produced during the disintegration of nuclei of radioactive substances is called:a. X-radiationb. gamma radiationc. scatter radiationd. back-scattered radiation

Q18. A photographic record produced by the passage of neutrons through a specimen onto a film is called:a. a fluoroscopic imageb. a radiographc. an isotopic reproductiond. none of the above

Q19. Possible reactions that can occur when a fast neutron strikes a nucleus are:a. scattering and radiative captureb. microshrinkage and static charges caused by frictionc. sudden temperature change and film contrastd. uniform thickness and filtered radiation


Q20. For inspection of radioactive objects or those that emit gamma radiation when bombarded with neutrons, a preferable detection method is the:a. direct exposure methodb. transfer methodc. isotopic reproduction methodd. electrostatic-belt generator method


Q21. Materials that are exposed to thermal neutron beams:a. must not be handled for at least 3 minutes after exposure has ceasedb. must be stored in a lead-lined roomc. may be radioactive after exposure to neutrons has ceasedd. should be monitored by means of a neutron counter

Q22. Hydrogenous material has a:a. high macroscopic scattering cross section (?)b. high absorption cross sectionc. high microscopic absorption cross sectiond. low microscopic scattering cross section

Q23. The penetrating ability of a thermal neutron beam is governed by:a. attenuation characteristics of the material being penetratedb. timec. source-to-film distance I=Ioe-μnt

d. all of the above


Q24. A graph showing the relationship between film optical density and exposure is called:a. a bar chartb. a characteristic curvec. an exposure chartd. a logarithmic chart

Q25. The three main steps in processing a radiograph are:a. developing, frilling, and fixationb. developing, fixation, and washingc. exposure, developing, and fixationd. developing, reticulation, and fixation

Q26. Radiographic contrast in a neutron radiograph is least affected by:a. developer temperatureb. radiographic exposure timec. radiographic beam collimationd. radiographic film fog

Ug?


Q27. Higher resolution can be achieved in direct neutron radiography by:a. placing lead intensifying screen between a gadolinium screen and filmb. increasing the L/D ratio of the collimation systemc. increasing the exposure timed. increasing the distance between the object and the film cassette

Q28. The main reason for using neutron radiography in place of X-radiography is:a. lower costb. higher resolution in all casesc. the ability to image objects and materials not possible with X -raysd. simpler radiographic procedure required than X -radiography

Q29. The best material for mounting specimens for neutron radiographic inspection is:a. cardboardb. plasticc. steeld. aluminum


Q30. Which of the following materials is best for making identification labels when using the neutron radiographic process?a. aluminumb. brassc. cadmium or gadoliniumd. lead


Q31. As a check on the adequacy of the neutron radiographic technique, it is customary to place a standard test piece on the source side of the cassette.This standard test piece is called:a. a reference plateb. a lead screenc. a penetrameterd. an image quality detector

Q32. A densitometer is:a. a meter used to measure neutron intensityb. an instrument used to measure film densityc. a meter used to measure the density of a materiald. a meter used to measure gamma content

Q33. The ability to detect a small discontinuity or flaw is called:a. radiographic contrastb. radiographic sensitivity.c. radiographic densityd. radiographic resolution

will


Q34. Movement, geometry, and screen contact are three factors that affect radiographic:a. contrastb. unsharpnessc. reticulationd. density

Q35. The difference between the densities of two areas of a radiographic film is called:a. radiographic contrastb. subject contrastc. film contrastd. definition


Q36. The selection of the proper type of film to be used for neutron adiographic examination of a particular part depends on the:a. thickness of the partb. material of the specimenc. neutron energyd. none of the above (all the above?)

Q37. When radiographing a part that contains a large crack, the crack will appear on the radiograph as:a. a dark, intermittent, or continuous lineb. a light irregular linec. either a dark or light lined. a fogged area on the radiograph

Q38. Radiographic sensitivity, in the context of defining the minimum detectable flaw, depends on:a. the graininess of the filmb. the unsharpness of the flaw image in the filmc. the contrast of the flaw image on the filmd. all of the above


Q39. An Image Quality Indicator is used to measure the:a. size of discontinuities in a partb. density of the filmc. amount of film contrastd. quality of the radiographic technique

Q40. Unwanted inclusions in a part will appear on a radiograph as:a. a dark spotb. a light spotc. a generalized gray area of varying contrastd. either a dark or a light spot or area depending on the relative absorption ratio of the part material and the inclusion material

Q41. A sheet of cadmium with an opening cut in the shape of the part to be radiographed may be used to decrease the effect of scattered neutrons, which undercuts the specimens. Such a device is called a:a. maskb. filterc. back-scatter absorberd. lead-foil screen

Q42. The accidental movement of the specimen or film during exposure or the use of a source-film distance that is too small will:a. produce a radiograph with poor contrast .b. make it impossible to detect large discontinuitiesc. result in unsharpness of the radiographd. result in a fogged radiograph

Q43. Dysprosium (16166Dy) conversion screens emit:

a. low-energy betas and gammasb. high-energy betas β, low-energy gammas γ, and internal-conversion electrons e (more reading!)c. beta particles onlyd. low-energy gamma rays only

Q44. Materials in common usage for moderation of fast neutron sources include:a. aluminum, magnesium, and tinb. water, plastic, paraffin, and graphitec. neon, argon, and xenond. tungsten, cesium, antimony, and columbium



TABLE 6. Properties of Some Thermal Neutron Radiography Conversion Materials








Q45. In the converter screen technique, the neutron image is produced by alpha, beta, or gamma radiation and it is thereby:a. used to measure neutron beam divergenceb. externally cooled during the processc. photographically more detectable than the unconverted neutron imaged. an important factor for determining Young's modulus of the material

Q46. Converter screen material characterized by lithium, boron, and gadolinium has little tendency to become radioactive but does:a. protect the radiographic film from excessive pressureb. recharge the focal point size of the neutron sourcec. filter and collimate the excess neutronsd. emit radiation immediately upon the absorption of a neutron

Q47. Gadolinium is frequently employed as a neutron absorber because of its:a. extremely low costb. high neutron absorption for a given thicknessc. ability to absorb gamma raysd. ability to diffract alpha particles






Q48. An excellent radiograph is obtained under given exposure conditions with a thermal neutron flux of 2 x 106 n/cm2∙s for 10 minutes. If other conditions are not changed, what exposure time would be required if the neutron flux was lowered to 1 x 106 n/cm2∙s?a. 5 minutesb. 10 minutesc. 20 minutesd. 30 minutes

Q49. Neutron converter screens should be inspected forflaws or dirt:a. dailyb. each time they are usedc. occasionallyd. when flaws are detected on the radiograph


Q50. The primary advantage of using a Cf-252 source for neutron radiography is its:a. portabilityb. low cost per unit neutron flux compared to other neutron radiographic sourcesc. high resolutiond. long useful life without source quality degradation


Q51. Neutron beams used in nondestructive testing normally contain:a. alpha particlesb. positronsc. gamma rays and neutronsd. X-rays

Q52. In neutron radiography, LID refers to the:a. limiting neutron energy divided by the neutron densityb. largest neutron flux in the system divided by the beam diameterc. distance from the neutron source to the object divided by the source diameterd. distance from the neutron source to the picture divided by the beam diameter

Q53. A type of neutron beam collimator is a:a. mean free path diaphragmb. divergent beam collimatorc. polycellular field generatord. neutron beam catcher


Q54. Commonly used converter screens are:a. gadolinium, dysprosium, and indiumb. neodymium, plutonium, and technetiumc. gadolinium, lead, and indiumd. gold. silver, and cadmium

Q55. In order to decrease geometric unsharpness:a. neutrons should proceed from as small a source as other considerations will allow (D)b. neutrons should proceed from as large a source as other considerations will allow (D)c. the film should be as far as possible from the object being radiographed (t!)d. the distance from the source to the material examined should be as small as practical (L)

Ug = Dt/(L-t)


Q56. High-resolution gadolinium conversion screens are produced by:a. flame spray techniquesb. being grown in large flat crystalsc. vacuum vapor depositiond. large brazing systems


Q57. In order to increase the neutron beam intensity:a. the LID could be loweredb. the neutron energy must be increasedc. the test specimen should be moved further from the filmd. a smaller source size could be used

Q58. Neutron exposure may be due to:a. the direct beam from the neutron sourceb. scatter radiation arising from objeCts in the direct beamc. both a and bd. neither a nor b

Q59. Gadolinium conversion screens emit:a. gamma rays and conversion electronsb. beta particles onlyc. alpha particles and positronsd. gamma rays only

Charlie Chong/ Fion Zhang Practical.NR Chapter 7


Q60. Which elements are commonly used in the indirect transfer method?a. gadolinium and cadmiumb. rhodium and samariumc. dysprosium and indiumd. cadmium and dysprosium


Q61. Which element is commonly used for direct neutron radiography?a. cadmiumb. indiumc. dysprosiumd. gadolinium

Q62. Neutron sensitive scintillators provide:a. high quality radiographs with long exposuresb. low quality radiographs with long exposuresc. low quality radiographs with short exposuresd. none of the above



Q63. Lead is:a. a good neutron shieldb. easily activated by neutronsc. a poor neutron absorberd. an efficient conversion screen

Q64. Neutron energy; exposure time, and film type are three important neutron radiographic parameters that can be controlled. What other parameter can be controlled?a. L/Db. conversion efficiencyc. type of conversion screend. both a and c

Q65. The purpose of vacuum cassettes is to:a. eliminate scattered radiationb. block unwanted gamma radiationc. assure intimate film-to-foil contactd. protect parts from the radiation emitted by the conversion screen


66. In making a californium isotope exposure in an unshielded area, you find the dose rate 1.9 m (6ft) from the source is 1200 mR/h. What would be thedose rate at 7.3 m (24ft)?a. 75 mR/hb. 100 mR/hc. 200 mR/hd. 300 mR/h

67. In developing film by hand technique without agitation:a. the radiograph will not show proper contrastb. it will be impossible to fix the radiographc. there will be a greater fogging of the filmd. there will be a tendency for each area of the film to affect the development of the area immediately below it

68. Film developed by automatic processors:a. will have improved detail of the imageb. will have a general increase in the film densityc. takes longer to develop than when processing manuallyd. will create less fog on the film


69. The emulsion side of a single-coated photographic X-ray-type film usedfor neutron radiography can be detected in the darkroom using standard safelights as the:a. printed identifying marks on the emulsion sideb. darker of the two sidesc. duller and lighter color of the two sidesd. printed identifying marks on the non-emulsion side

70. The purpose of film containers is to:a. protect the film from lightb. protect the film from scratchesc. neither a nor bd. both a and b

71. The two most common causes for excessively high density radiographs are:a. insufficient washing and overdevelopingb. contaminated fixer and insufficient washingc. overexposure and contaminated fixerd. overexposure and overdevelopment


Q72. Single-emulsion high-resolution X-ray film is very good for neutron radiography because:a. it has a very thin emulsionb. it is sensitive to low-energy radiation and insensitive to high-energy radiationc. it is faster than other filmsd. both a and b

Q73. Which of the following materials is suited for construction of vessels or pails used to mix processing solutions?a. stainless steelb. aluminumc. galvanized irond. tin

Q74. Excessive exposure of film to light prior to development of the film will most likely result in:a. a foggy filmb. poor definitionc. streaksd. a yellow stain


Q72. Single-emulsion high-resolution X-ray film is very good for neutron radiography because:a. it has a very thin emulsionb. it is sensitive to low-energy radiation and insensitive to high-energy radiationc. it is faster than other filmsd. both a and b


Q75. White crescent-shaped marks on an exposed X-ray film are most likely caused by:a. crimping film after exposureb. crimping film before exposurec. sudden extreme temperature change while processingd. a warm or exhausted fixer

Q76. Reticulation resulting in a puckered or netlike film surface is probably caused by:a. crimping film after exposureb. sudden extreme temperature change while processmgc. water or developer on unprocessed filmd. excessive object-film distance


Q77. Frilling 皱边,脱模 or loosening of the emulsion from the base of the film is most likely caused by:a. water or developer on unprocessed filmb. the low temperature of processing solutionsc. developer solution contaminationd. a warm or exhausted fixer solution

Q78. When the minute silver grains, on which the X-ray film image is formed, group together in relatively large masses, they produce a visual impression called:a. air bellsb. graininessc. reticulationd. frilling


Q79. Static marks, which are black tree-like or circular marks on a radiograph,are often caused by:a. the film being bent when inserted in a cassette or holderb. foreign material or dirt embedded in screensc. scratches on lead foil screensd. improper film handling techniques

Q80. The purpose of agitating an X-ray film during development is to:a. protect the film from excessive pressureb. renew the developer at the surface of the filmc. disperse unexposed silver grains on the film surfaced. prevent reticulation


Q81. When manually processing films, the purpose of tapping the hangerssharply two or three times after the films have been lowered into thedeveloper is to:a. disperse unexposed silver grains on the film surfaceb. prevent frillingc. dislodge any air bubbles clinging to the emulsiond. all of the above

Q82. The decrease in activity of the developer solution is compensated by:a. constant agitationb. maintaining processing solutions within the recommended temperature rangec. avoiding contamination from the wash bathd. adding replenisher


Q83. The purpose of fixation is to;a. remove all the undeveloped silver salts of the emulsionb. leave the developed silver as a permanent imagec. harden the gelatind. all of the above

Q84. For the best results when manually processing film, solutions should be maintained within the temperature range of:a. 65 °F and 75 °Fb. 65 °C and 75 °Cc. 75 °F and 85 °Fd. 75 °C and 85 °C


Q85. Water spots on films can be minimized by:a. the rapid drying of wet filmb. immersing wet film for 1 or 2 minutes in a wetting agent solutionc. using a fresh fixer solutiond. cascading water during the rinse cycle

Q86. The most suitable films for producing neutron radiography are:a. red sensitive filmsb. PolaroidTM filmsc. industrial X-ray filmsd. medical X-ray films


Q87. The normal development time for manually processing X-ray film is:a. 12 to 18 minutes in processing solutions at 75 °Fb. 3 to 8 minutes in processing solutions at 75 °Fc. 12 to 18 minutes in processing solutions at 68 °Cd. 5 to 8 minutes in processing solutions at 68 °F

Q88. A properly exposed radiograph that is developed in a solution at a temperature of 58 °F will be:a. overdevelopedb. underdevelopedc. foggedd. damaged by frilling


Q89. An advantage of the fountain-pen type of ionization chamber used to monitor radiation received by personnel is that:a. it provides a permanent record of accumulated dosageb. it provides an imediate indication of dosagec. it is the most sensitive detector availabled. all ofthe above

Q90. What radiation dose would be dangerous, if not fatal, if applied to the entire body in a short period of time?a. 1.5 to 15 R (rem)b. 25 to 70 R (rem)c. 200 to 800 R (rem)d. all of the above doses would most likely be fatal


Too much to remember?


91. The average thermal neutron flux that gives a dose of 100 mrem in 40 hours is:a. 700 n/cm2•sb. 70 n/cm2∙sc. 7 n/cm2∙sd. 0.7 n/cm2∙s

92. When working with a neutron radiography facility, the radiation expected is:a. gammab. betac. neutrond. all of the above

93. The intensity of neutron radiation is usually measured m:a. roentgensb. ergsc. neutrons/cm-sd. neutrons/cm


94. What does the term (R/h) refer to when speaking of intensity?a. radiation limits for humansb. roentgens per hourc. X -rays per hourd. radiation in hydrogen

95. Small amounts of exposure to neutrons or gamma rays:a. may have a cumulative effect that must be considered when monitoring for maximum permissible doseb. will be beneficial since they build up an immunity to radiation poisoning.c. will have no effect on human beingsd. will have only a short-term effect on human tissues


96. Overexposure to neutron or gamma rays may cause damage to human:a. blood and skinb. skinc. internal organsd. all of the above

97. A general rule used-to define an excessive amount of radiation exposure is:a. anything above 0.4 R (rem) per week, although small amounts of radiation (0.4 R [rem] per week or less) are beneficial since they build up immunity to these raysb. any dose over 5 R (rem) per weekc. any dose that causes a mid-range reading on a Geiger counterd. any unnecessary exposure to radiation


98. A primary disadvantage of the fountain-pen type of ionization chamber used to measure the amount received by personnel is the:a. delay necessary before the results of a measurement are knownb. inaccuracy of such devices in measuring scatter radiationc. inability of such a device to provide a pennanent record of exposured. cost of recharging such devices

99. The exposure of personnel to X- and gamma radiation can be determined by means of:a. film badgesb. dosimetersc. radiation metersd. all of the above


100. The intensity of gamma rays is measured in:a. roentgensb. ergsc. roentgens per unit of timed. H & D units

101. Divergent neutron beams:a. do not obey the Inverse Square Law of distanceb. obey the Inverse Square Law of distancec. use lead for shieldingd. none of the above

102. A radioactive source used for neutron radiography is:a. PU-239b. Co-60c. Cs-137d. Cf-252


103. The half-life of Cf-252 is:a. 9 yearsb. 2.6 yearsc. 6 monthsd. 47.5 years

104. Cf-252 is:a. a spontaneous fission sourceb. a fissile sourcec. both a and bd. neither a nor b

105. A normally desirable feature of a thermal neutronbeam for neutron radiography is:a. low gamma radiation intensityb. relatively low, fast neutron intensityc. low, angular divergence (so resolution capabilities for thicker objects can be good)d. all of the above

http://www.chemicalelements.com/elements/cf.html


Q106. To achieve uniformity in neutron radiographs, it is recommended that:a. manual processing be usedb. automatic processing be usedc. it does not matter which process to used. the Shockly process be used

Q107. The approximate energy of a thermal neutron is:a. 1 MeVb. 0.026 eV (0.01~0.3ev)c. 12 KeVd. 114eV

Q108. The material that slows down neutrons is called:a. a moderatorb. an accumulatorc. a limitord. none of the above



TABLE 6. Properties of Some Thermal Neutron Radiography Conversion Materials


109. A good moderating material is:a. waterb. iron.c. leadd. all of the above

110. If the temperature decreases, the energy of a thermalneutron will:a. increaseb. decreasec. stay the samed. none of the above


111. A main disadvantage of gadolinium screens is:a. that they are expensiveb. that they are magneticc. that they have poor sensitivity to neutronsd. both a and b

112. The main advantage of a divergent beam collimator is:a. that no dividing slats are used which could possibly cause lines on a radiographb. that there is a minimal neutron reflection if the sides of the collimator are made of a neutron absorbing materialc. that it is relatively simple to manufactured. all of the above


Q113. The main disadvantage of a divergent beam collimator is:a. that less resolution is possible than with a parallel beam collimator of the same lengthb. the large physical size of the collimator to achieve L/D ratios that are necessary for good resolutionc. that the small end of the collimator near the effective thermal neutron source is small, therefore minimizing the displacement of the moderatord. all of the above

Q114. The definition of a neutron is:a. the uncharged particle having a mass slightly greater than that of the protonb. the uncharged particle having a mass slightly less than that of a protonc. the positive charged particle having a mass slightly less than that of the protond. none of the above


115. To an Operational Health Physicist, the abbreviation, RBE means:a. Rapid Biological Energyb. Roentgen Background Embrittlementc. Relative Biological Effectivenessd. both a and b

116. The cross section is expressed in area units, the most common being the one that is equal to 10-24 cm2 This is the:a. femtob. teroc. barnd. watt


Q117. The transfer exposure method is used because:a. it is not sensitive to gamma radiationb. it has greater radiographic sensitivity than the direct exposure method using gadoliniumc. it is faster than the direct exposure methodd. the screens used in this method emit only internal conversion electrons of about 70 ke V

Q118. Which of the following elements has the largest mass absorption coefficient for thermal neutrons?a. boronb. leadc. gadoliniumd. copper


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.


Q119. The term “ macroscopic cross section (Σ) " is synonymous with the:a. linear attenuation coefficient (μ) for neutronsb. microscopic cross section (σ) for neutronsc. mass attenuation coefficient (σ/ρ) for neutronsd. cadmium ratio for neutrons

Comments:μ = ρ∙N/A∙σ, σ = microscopic cross section, Σ= ρ∙σ = macroscopic cross section

MACROSCOPIC SCATTERING CROSS SECTIONSThe distinction between macroscopic and microscopic cross-section is that the former is a property of a specific lump of material (with its density), while the latter is an intrinsic property of a type of nuclei.https://en.wikipedia.org/wiki/Nuclear_cross_section


Reading-One atASNTNRTMQA123Level-II



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Level 2 Answers Neutron Radiographic Testing Method


Q1. A nuclear reactor produces neutrons that have energies distributed fromless than 0.01 eV to greater than 20 MeV. For most neutron radiography, thethermal energy group is used. This group has energies:a. below 0.01 e Vb. 0 to 0.3eVc. 0.3 to 10 000 eVd. 10 keV to 20 MeVe. >20 MeV

Q2. The primary radiation mechanism for darkening X-ray film when the directradiography process is used employing gadolinium screens is:a. alpha particlesb. electronsc. gamma raysd. light emission



3. Neutron radiography is an excellent tool for determining:a. the coating thickness of aluminum oxide on anodized aluminumb. voids in thick steel castingsc. the integrity of thin plastic material within a lead housingd. voids in thick plastic sections

4. Which of the following materials is the greatest attenuator of thermal neutrons?a. aluminumb. copperc. lithiumd. Iron


Q5. Thermal neutrons that are relatively free from higher energy componentsare obtained by allowing neutrons from the source (reactor, radioactivesource, accelerator) to pass through moderating material. This material maybe:a. waterb. paraffinc. graphited. all of the above

Q6. The sample part may become radioactive as the result of neutron activation during the neutron exposure. As a general rule, the level of radioactivity will be:a. highb. very lowc. dangerously highd. none of the above


Q7. The absorption of neutrons in an object depends upon:a. the neutron cross sectionb. the nuclides in the object I=Ioe –μnt, μn = [ρN/A]∙σc. the object thickness N= Avogadro Number, A= mass atomic weight

d. all of the above ρ = density g/cm2, σ=neutron cross section cm2

Q8. The energy of the neutrons in a neutron beam:a. is the same for all neutron beamsb. does not affect the radiographic parametersc. has no bearing on neutron absorption in the material to be radiographedd. directly influences the choice of usable conversion screens

Avogadro’s Number = 6.02214129x 1023 mol-1https://en.wikipedia.org/wiki/Avogadro_constant


Q9. Gadolinium and cadmium have:a. a flat neutron cross section across all energiesb. a cross section which peaks at thermal energiesc. a high thermal neutron cross section which drops off rapidly at higher energiesd. their highest neutron cross section at 1.4 eV (resonance?)

Q10. Which of the following conversion screens has the longest half-life?a. Dysprosium (2.3 hours)b. Indium (54 min)c. Cadmium (stable)d. Gadolinium (stable)






11. The unique and important properties of the neutron in neutronradiography come primarily from the fact that it is a nuclear particle that iselectrically neutral. The lack of electric charge means that its electrostaticinteraction with the atom's electrons is:a. almost completeb. scatteredc. almost completely negligibled. such that the electrons and neutrons combine with each other

12. The rare earths are frequently used in neutron radiography. An interestingfeature of this family of elements is:a. that they have nearly identical chemical properties and are, therefore, difficult to tell apartb. that they make up about one-sixth of all naturally occurring elements, but the entire group occupies only one position in the Periodic Tablec. that they have large absorption cross sections for neutronsd. all of the above


13. A thin sheet of gadolinium foil, in intimate contact with photographic filmduring neutron exposure, will increase film density because:a. it fluoresces and emits visible light, which helps expose the filmb. it emits electrons that darken the filmc. it absorbs the scattered radiationd. it prevents back-scattered radiation from fogging the film

14. For direct neutron radiography, precaution has to be taken to reduce thegamma ray background of most sources as this tends to obscure the neutronradiograph. This may be done by:a. using filtration of gamma rays (Bi, Pb)b. increasing the source-to-film distancec. both a and bd. neither a nor b


Q15. The transfer exposure technique, sometimes called the indirect technique, uses neutron converters that have a reasonably long radioactive half-life. Which of the following would be a good candidate?a. Indium (54min)b. Dysprosium (2.3hrs)c. both a and bd. neither a nor b

Q16. Which of the following neutron radiography converter foils cannot be used for transfer or indirect radiography?a. dysprosiumb. indiumc. Gadolinium (stable)d. Gold (2.7d)


Q17. The quality of the results from a neutron radiographic facility is best determined by:a. reference standardsb. image-quality indicatorsc. neutron flux measurementd. densitometer readings

Q18. Flaws in the imaging screens can be separated from actual flaws in a part being radiographed by:a. performing a photographic copy of the original neutron radiograph using X -ray duplicating filmb. comparing a neutron radiograph of the parts to a blank neutron radiograph of the same imaging screen with no parts in placec. increasing the exposure time of the radiographd. decreasing the temperature of the developer solution


19. The best method for determining how resolution affects the ability tointerpret the radiograph of parts is by:a. radiographing parts that have known measured defectsb. using a penetrameterc. using a penetrameter containing cadmium Wedgesd. using a penetrameter containing plastic wedges

20. The slope of a straight line joining two points of specified density on the characteristic curve of a film is known as the:a. speed of the curveb. latitudec. average gradientd. density


21. The range of densities which are satisfactory for interpretation is a measure of the:a. subject contrast of a radiographb. sensitivity of a radiographc. latitude of a radiographd. definition of a radiograph

22. The transmission of neutrons by a material varies:a. directly with the square of the distance from the sourceb. directly with the thickness of the materialc. inversely with the amount of scattering in the materiald. exponentially with the thickness of the material


23. Which of the following is not a factor in determining subject contrast?a. the nature of the specimenb. the neutron energyc. the type of film usedd. the intensity and distribution of the scattered radiation

24. When viewing a radiograph, an image of the back ofthe cassette superimposed on the image of thespecimen is noted. This is most likely due to:a. undercutb. overexposurec. neutron intensity being too highd. back scatter


25. A qualitative term often used to indicate the size of the smallest detail which can be seen in a radiograph is:a. radiographic sensitivityb. radiographic definitionc. radiographic contrastd. subject contrast


Q26. The quantitative measure of film blackening is referred to as:a. definitionb. photographic densityc. film contrastd. radiographic contrast

Q27.A curve that relates density to the logarithm of exposure or of relative exposure is called:a. a sensitivity curveb. a density-exposure curvec. a characteristic curved. an X -ray intensity curve


28. Subject contrast is affected by:a. thickness differences in the specimenb. neutron energyc. scattered radiationd. all of the above

29. Contrast enhancement of a neutron radiograph can be achieved by:a. using photographic techniques with X-ray duplicating filmb. increasing the radiography system resolutionc. varying the object-to-film distanced. increasing the gamma radiation reaching the film from the source


Q30. The uniformity of a neutron radiograph is best determined by measuring the density of a:a. neutron radiograph at several locations with many parts in placeb. neutron radiograph at several locations with no parts in placec. photographic copy of a neutron radiograph with many parts in placed. photographic copy of a neutron radiograph with no parts in place

Q31. The density measurement in a neutron radiograph that is of most interest in determining part flaws is the density measurement:a. at the center of the filmb. at the comer of the filmc. at the edge of the filmd. in the area of interest within the parts being radiographed


32. A neutron radiograph beam from a reactor was measured to have a thermal neutron flux of 3.4 x 106 n∙cm-2∙ s-1 and a gamma rate of 26 R/h. Which of the following would be the neutron to gamma ratio in units of n∙cm-2

∙mR-1?a. 4.7 x 102

b. 4.7 X 105 3.4 x 106 / [(26/60x60) x 103] C. 2.1 X 105

d. 2.1 X 102

Q33. In direct neutron radiography using gadolinium, cleanliness is essential when handling film cassettes because:a. dust or lint between the film and the gadolinium shows as a flaw in the radiographb. dust on the outside of the film cassette is always visible in the neutron radiographc. dust is highly absorbent to neutronsd. dust greatly affects the development of X-ray film


34. A dysprosium conversion screen is exposed in a thermal neutron beam. After decay time of 6.9 hours: (3 half-life)a. 3/4 of the original activation will remainb. 1/2 of the original activation will remainc. 1/8 of the original activation will remain (1/2)3

d. there will be no change from original activation levels

35. When sharp, black, bird-foot shaped marks appear on the film in areas where there are no possible discontinuities, they are probably caused by:a. prolonged development in an old developerb. exposure of the film by natufal cosmic radiationc. static charges caused by frictiond. inadequate rinsing after fixing


36. Images of discontinuities close to the source side of the specimen become less clearly defined as the:

a. source-to-object distance increasesb. thickness of the specimen increasesc. size· of the neutron source decreasesd. thickness of the specimen decreases

37. The amount of unsharpness of a radiograph is:a. directly proportional to the object-to-film distance and inversely

proportional to the size of the sourceb. directly proportional to the size of the source and inversely

proportional to the source-to-object distancec. inversely proportional to the object-to-film distance and directly

proportional to the source-to object distanced. inversely proportional to the size of the source and the object-to-film

distance


38. The most commonly used converter material is:a. copperb. tungstenc. goldd. gadolinium

39. As the effective energy of the radiation from the conversion screen increases:a. film graininess increasesb. film graininess decreasesc. radiographic definition decreasesd. film speed decreases


40. A general rule governing the application of the geometric principles of shadow formation states that the:

a. neutrons should proceed from as large a source area as other considerations will allow

b. distance between the source and material should be as small as practicalc. film should be as far as possible from the object being radiographedd. axis of the beam should be as nearly perpendicular to the film as

possible, to preserve spatial relationships

41. A neutron radiograph made with an exposure of 12 minutes has a density of 0.8 in the region of maximum interest. It is desired to increase the density

in this area to 2.0. By reference to a characteristic curve of the film, it is found that the difference in between a density of 0.8 and 2.0 is 0.76. The antilogarithm of 0.76 is 5.8. What must be the new exposure time to produce a radiograph of density 2.0?

a. 30 minutesb. 21.12 minutesc. 69.6 minutesd. 16 minutes


42. Which of the following factors will not materially influence the image density of a neutron radiograph?a. the type of film usedb. the size of the filmc. the type of conversion screen usedd. the exposure time

43. X-ray films with large grain size:a. will produce radiographs with better definition than film with small grain sizeb. have slower speeds than those with a relatively small grain sizec. have higher speeds than those with a relatively small grain sized. will take longer to expose properly than film with a relatively small grain size


44. The uneven distribution of developed grains within the emulsion of a processed X-ray film causes the subjective impression of:a. graininessb. Streaks 条纹c. spotsd. white scum

45. An X-ray type film used for neutron radiography having wide latitude also has, by definition:a. poor definitionb. low contrastc. high speedd. none of the above


46. The gradient of a characteristic curve for a photographic film for neutron radiography is the greatest as a density of:a. <0.5b. 0.5c. 1.0d. >1.0

47. For practical purposes, the shape of the characteristiccurve of an X -ray film is:a. independent of the type of film usedb. independent of the energy of the neutron beamc. drastically changed when neutron energy is changedd. primarily determined by the subject contrast

48. The interval between the time a film is placed in a fixer solution and the time when the original diffuse, yellow milkiness disappears is known as the:a. clearing timeb. fixing timec. hardening timed. oxidation time

49. Improper geometric factors, poor contact between film and conversion screen, and graininess of film are possible causes of:a. high film densityb. poor definitionc. fogged filmd. increased contrast



50. It is known that the density of a film increases with increasing exposure up to a maximum value. Increasing the exposure beyond this point results inan actual decrease of density. This phenomena is referred to as:a. density-intensity turnaboutb. subject contrast inversionc. film contrast inversiond. reversal


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51. The activity of the fixer diminishes after being used for a period of time because:a. the active ingredients evaporateb. the active ingredients are absorbed by the radiographc. the fixer solution accumulates soluble silver saltsd. the active ingredients settle to the bottom of the tank

52. Developer solution should be discarded when the quantity of replenisher added equals:a. the original quantity of developerb. 2 to 3 times the original quantity of developerc. 5 to 6 times the original quantity of developerd. 10 times the original quantity of developer


53. Agitation of the X-ray film during the development process by means of mechanical stirrers or circulating pumps may:a. speed the developing cycleb. help replenish the developerc. cause undesirable preferential flow of developer along certain pathsd. cause reticulation

54. In processing radiographs, the hourly flow of water in the wash tank should be:a. 2 to 3 times the volume of the tankb. 4 to 8 times the volume of the tankc. at least 151 L (40 gal) per hourd. varied continuously in proportion to the number of radiographs being developed


55. The slope (steepness) of a characteristic curve is a measure of the:a. subject contrastb. radiographic definitionc. radiographic contrastd. film contrast

56. As the development time increases:a. the characteristic curve grows steeper and moves to the leftb. the characteristic curve grows steeper and moves to the rightc. the characteristic curve remains the same in shape but moves to the leftd. there is little effect on the characteristic curve


57. Which of the following instruments would most likely by used to detect small leaks in a radiation barrier?a. a film badgeb. a fountain pen type of ionization chamberc. a Geiger counterd. a dosimeter

58. The quantity of neutron radiation upon an area of film for an exposure:a. is the product of the neutron flux and timeb. is the neutron fluxc. varies exponentially with timed. varies inversely proportional with time


59. The energy of the neutron is expressed by which of the following units of measurement?a. curieb. roentgenc. half-lifed. electron volts

60. Neutrons for fast-neutron radiography are obtainable from:a. acceleratorsb. radioactive sourcesc. reactorsd. all of the above


61. "Macroscopic cross section" as applied to neutrons is analogous to for γrays:a. cross sectionb. mean free pathc. attenuation coefficientd. wavelength

62. For high quality radiographs, a 25-micrometer thick gadolinium screen combined with fine-grain X-ray film requires an exposure of about:a. 3 x 103 n/cm2

b. 3 x 105 n/cm2

c. 3 x 107 n/cm2

d. any of the above


63. Neutron monitoring outside a radiography exposure area may be done with:a. a Geiger counterb. a "cutie-pie" (ionization chamber)c. a BF3 proportional counterd. all of the above

64. Special neutron-sensitive film dosimeters:a. should be worn by neutron radiographersb. employ a film-screen combination principal similar to radiographyc. also give a measure of γ dosed. all of the above


65. For the same beam intensity, which of the following will give the largest biological dose?a. fast neutronsb. thermal neutronsc. gamma raysd. all are equal by definition

66. For fast-neutron monitoring, a thermal-neutron sensitive radiation counter may be used in conjunction with:a. a moderatorb. an ionization chamberc. a conversion foild. a collimator


67. If the biological dose rate at 1.5 m (5 ft) from a point source of radiation is10 mrem/h, then the minimum permissible distance at which a worker mayremain for continuous (full work week) exposure is about: (Assume maximumexposure of 100 mrem/week)a. 3m (10ft)b. 6 m (20ft)c. 15.2 m (50ft)d. 30.5 m (100ft)

68. In a radiation area where the dose rate is established to be 25 mrem/h, aworker during a work week may spend no more than: (assume minimumexposure of 100 mrem/week)a. 6 minutesb. 1 hourc. 4 hoursd. 8 hours


69. Upon exiting from a radiation zone, you begin a G-M survey of an object. The needle begins to rise and then suddenly drops to zero. You should assume that the:a. G-M tube has rupturedb. G-M jammed because of too much radiationc. G-M probe has become grossly contaminatedd. rubbers are not contaminated

70. The G-M cannot be used to establish dose rates because:a. the G-M is not reliable and tends to driftb. the beta shield is too thick on the G-Mc. the G-M does not account for the degree of ionization or energy absorption of ionizing particles or photonsd. the G-M is designed to detect only alpha contamination on scintillators


71. A direct reading pocket dosimeter may be sensitive to what radiation?a. βb. γc. γ, nd. either a or b

72. A film dosimeter useful for neutron radiographers will be sensitive to what radiation?a. α, β, γ, nb. α, β, γc. β, γ, d. β, γ, n


73. Thermal-neutron-sensitive radiation counters usually contain:a. gadoliniumb. cadmiumc. borond. lead

74. If 2 mm (0.08 in.) of plastic attenuates a thermal neutron beam by a factor of 2, then 20 mm (0.8 in.) will attenuate it by approximately a factor of:a. 10b. 100c. 1000d. 10000


75. The high attenuation of thermal neutrons by plastics is due primarily to:a. scatteringb. absorptionc. both a and bd. none of the above


76. Photographic density is a quantitative measure of:a. film thicknessb. film weightc. film blackeningd. object opacity


77. Film exposed to a density of 2 will transmit what percentage of the light incident upon it?a. 50%b. 25%c. 2%d. 1%

78. An image-quality indicator is:a. a scanning densitometerb. a chemical stainc. a penetrameterd. all of the above


79. Radiography using the transfer method implies that the imaging screen:a. is placed behind the filmb. is placed in front of the filmc. is very thind. becomes radioactive

80. In the list below, the best filter material for making an epithermal neutron beam is:a. cadmiumb. waterc. borond. lead


81. Fast neutron attenuation:a. increases significantly with increasing atomic massb. decreases significantly with increasing atomic massc. has significant random variations with atomic massd. is similar for most materials

82. Which of the following is most widely used in the detector for imaging fast neutrons?a. hydrogenous materialb. goldc. aluminumd. lithium


83. The linear attenuation coefficient for neutrons is described in the following equation: μ = Nσt, Which of the following statements is true?a. N = number of nuclei per cm3 of attenuating materialb. σt =total cross section (cm2 ), equal to the sum of absorption and scattering cross sections (σs + σa )c. σa = absorption cross sectiond. all the above

84. Real-time imaging of thermal neutron radiography can be performed with which of the followingdetectors? a. gadoliniumb. dysprosiumc. zinc sulfide + lithium fluorided. europium


85. A neutron beam undergoes which of the following interactions when penetrating matter?a. scatterb. pair productionc. Thompson effectd. compton scattering

86. A Geiger-Muller instrument is a:a. pocket sized dosimeterb. scintillation counterc. hand-held survey meterd. proportional counter


87. The thermalization factor is the:a. ratio between the total 4π fast neutron yield and the peak thermal

neutron fluxb. dose of ionizing radiation that can be absorbed per unit volumec. mean square distance while slowing downd. mean time spent diffusing in a test object before being captured in a

detector


88. Energy classification places epithermal neutrons in the range:a. below 0.01 eVb. from 0.3 eV to 100 keVc. from 0.3 to 10 000 eV (0.3ev ~ 10kev)d. from 10 keV to 20 MeV


89. A shutter for turning the neutron beam ON and OFF at a nuclear reactor can be accomplished by:a. the electronic circuitryb. a small mechanical camera shutterc. boron shuttersd. aluminuin shutters

90. Gadolinium screens have been shown to resolve high contrast images separated by distances as small as:a. 2.5 mm (0.1 in.)b. 1 mm (0.04 in.)c. 0.1 mm (0.004 in.)d. 0.01mm (0.0004 in.)


91. The best radiographic resolution and contrast capability for direct exposure radiography has been obtained with:a. gadolinium screensb. indiumc. silverd. cadmium

92. Radiography requiring utmost speed and no more than 0.05 mm (0.002 in.) resolution would require which of the following detectors?a. gadolinium screensb. scintillator screensc. dysprosium screensd. silver screens


93. In which of the following neutron beams does the intensity follow the inverse square law?a. divergent beamb. soller slit beamc. neutron spectrometer beamd. monochromatizing crystal beam

94. Neutron radiography:a. complements X-radiographyb. can discriminate between neighboring elements such as boron and carbonc. can inspect large thicknesses of heavy metalsd. all of the above


95. Neutron radiography extends radiographic capability for detecting cracks in small:a. aluminum pinsb. iron pinsc. magnesium pinsd. plutonium pins

96. Film fogging during radiography of radioactive materials (5000 R/h at 31 cm [1ft]) is minimized by using:a. direct X-radiographic methodsb. pinhole autoradiographyc. transfer method with dysprosium screensd. photography


97. What radiography technique should be used for obtaining improved penetration of 20% Pu, U-235 enriched fuel pellets, ~ 6 mm diameter?a. thermal neutron with gadolinium screenb. epithermal neutron and indium screenc. epithermal neutron and dysprosiumd. autoradiography

98. Neutron radiography can be used for inspecting which of the following applications?a. presence of explosive in a metal deviceb. presence of foreign material such as oilc. lubricants in metal systemsd. hydrogen content in metalse. all of the above


99. Disadvantages of the transfer technique include that it:a. is time consumingb. requires many imaging foilsc. provides lesser resolution than the gadolinium direct methodd. costs more to use dysprosium foils than gadolinium foilse. all of the above


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Level 3 Answers Neutron Radiographic Testing Method


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End Of Reading 1


8. Converter screen uses gadolinium which emit beta particles (!), Gd.

Β particle or conversion electron?





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Understanding Neutron Radiography Reading IV-Part1