Take A Free ASNT NDT NR Level 3 Exam Practice Test

Here you can take a free ASNT NDT NR Level 3 Exam Practice Test with latest Neutron Radiographic Testing Method Physical Principles Level III Questions and Answers

A thermal neutron beam is extracted horizontally from a reactor. Neglecting to scatter by air or other materials in its path, what would you expect the beam path over the first 15 m (49 ft) to do?

a. remain horizontal because the neutrons are essentially unaffected by gravity

b. drop by 23 mm

c. drop by 228 mm

d. drop by 15 mm (0.6 in.)

Nature of Penetrating Radiation

Neutrons:

a. Are uncharged particles

b. Have a mass slightly less than a proton

c. Are found in the nuclei of all isotopes

d. Have all of the above properties

Which of the following is true for neutron radiographic conditions?

a. hydrogen in the object will more nearly stop high energy neutrons (well above 0.025 eV) than it will typical thermal neutrons (close to 0.025 eV)

b. epithermal neutrons (of indium resonance energy) will cause more ionization per neutron than thermal neutrons and therefore cause more risk from radiation damage to sensitive materials

c. in neutron radiography of a typical fast reactor fuel pin, each thermal neutron captured normally gives rise to about two fast neutrons and significantly delayed gamma radiation

d. the angle of scatter for fast neutrons will, on average, be greater than that of thermal neutrons and this is one factor contributing to the difficulty of clear fast neutron radiography

Interaction between Penetrating Radiation and Matter

When the mass absorption coefficient for neutrons is plotted as a function of the atomic number of the absorber, it presents a:?

a. regularly increasing curve

b. random curve

c. single peak curve

d. double peak curve

You have to neutron radiograph an object that required visualization of very small hydrogenous details behind 76 mm (3 in.) of steel. The standard technique using a tangential beam on a reactor proves insufficient. What would be the recommended approach?

a. send the object to a high intensity (or flux boosted) Cf-252 system where it could be exposed for very long periods (e.g., over a weekend)

b. send the object to a Van de Graaff neutron radiography system and request fast neutron point source neutron radiography using sulfur activation transfer to avoid any gamma fog

c. send the object to a facility performing cold neutron radiography.

d. send the object to a pulsed reactor and use real-time imaging in conjunction with the time of flight methods

Which of the following statements is incorrect?

a. neutron radiography excels in imaging plastic objects behind metal walls

b. X-radiography is eminently suitable for imaging complicated nonradioactive metal objects that are not too thick (i.e., less than 1 cm [0.4 in.])

c. neutron radiography is suitable for imaging items composed of iron and plastic regardless of the thickness of the plastic provided only that the iron is less than 25 mm (1 in.) thick.

d. indium resonance neutrons are frequently used to enhance the penetration of thick plastic objects

From the following penetrating radiations, which one can best be used to radiograph a cylinder of hydrocarbon plastic that is 50 mm (2 in.) in diameter in which we want to image embedded metal parts?

a. fast neutrons

b. thermal neutrons

c. cold neutrons

d. X-rays Imaging by Film.

Following neutron capture in a gadolinium-foil converter, which of the following is emitted from the foil surface and interacts in the photographic emulsion to produce a high-resolution latent image?

a. X-rays

b. gamma rays

c. alpha particles

d. conversion electrons.

A fact concerning the reciprocity law failure in neutron radiography is that:

a. film density of X-ray films is not proportional to log 10 exposure

b. film density of light-sensitive films is not proportional to the exposure

c. reciprocity law failure of X-ray films is partially alleviated by development at higher temperatures (80 °F)

d. reciprocity law failure of light-sensitive films is partially alleviated by exposure to scintillator converters at low temperatures.

10.

When a neutron-sensitive fluorescent screen is used in conjunction with a photographic film, the film exposure satisfies the Schwarzchild relationship, E=I+p, where p = 0.75. This means that, if a flux, I, gives a satisfactory exposure in 1 minute, a flux 1/10 as great, I₀ /10, will require an exposure time of approximately:

a. 5 minutes

b. 10 minutes

c. 20 minutes.

d. 40 minutes

11.

The photographic latent image may be defined as that radiation-induced change in a grain or crystal that renders the grain readily susceptible to the chemical action of a developer. The material of the latent image itself is typical:

a. silver ions

b. silver atoms.

c. silver oxide

d. silver iodide

12.

Track etch neutron imaging differs from dysprosium transfer imaging in which of the following ways?

a. it provides higher contrast

b. it is unaffected by gamma fogging from the beam or object

c. it provides poorer edge definition

d. it is suitable for use in low-intensity beams where long exposure times are acceptable.

13.

Imaging by Fluorescent Materials

When fluorescent materials are employed for neutron radiographic imaging, reciprocity failure is often encountered. This is due to the fact that:

a. greater energy is deposited in the film grain by light emission from the fluorescent screen to render the grain developable than can be achieved with metal foil conversion screens

b. less energy is deposited in the film grain to render screens developable than with metallic conversion.

c. the fluorescent screen is electrically nonconducting

d. the fluorescent screen does not respond to gamma radiation

14.

Imaging by Electronic Devices

Electron imaging devices invariably provide:

a. amplification of both signal and noise including statistical noise.

b. intimate film to conversion screen contact

c. discrimination against scattered neutrons

d. direct external conversion electrons of varying energies

15.

Substitution of gadolinium-oxysulfide for ZrS-Li°F as the input converter is an electronic imaging device will normally result in:

a. increased discrimination against gamma radiation

b. increased inherent unsharpness

c. the need for increased electronic gain.

d. decreased image retention between frames

16.

Radiometry

The “cadmium ratio” of a neutron refers to:

a. the ratio of thermal neutron flux above cadmium cutoff

b. the ratio of thermal neutron flux to gamma dose rate

c. the ratio of total neutron flux to the neutron flux above about 0.5 eV.

d. the ratio of neutron flux above about 0.5 eV to the thermal neutron flux

17.

SOURCES OF NEUTRONS Neutron Sources-General Reactors

High-quality neutron radiographs are produced by reactor neutron sources because of the:

a. absence of fast neutrons

b. the large physical size of the reactor core

c. strong resonance in the reaction cross section at 120 keV

d. high core flux in the range of 10¹² to 5 x 10¹⁴ n/cm²-s.

18.

Accelerators

Which one of the following generators has a significant neutron yield at the low bombardment energies?

a. Van de Graaf

b. T(d,n).

c. linear accelerator

d. D(d,n)

19.

Isotopic Sources

The neutron-producing reaction of Cf-252 is:

a. spontaneous fission.

b. (α, n) reaction

c. (γ, n) reaction

d. none of the above

20.

Of the isotopic sources employed for neutron radiography, which of the following sources decays by the spontaneous fission process?

a. Sb-124-Be

b. Po-210-Be

c. Cf-252.

d. none of the above

21.

RADIATION DETECTORS Imaging Converter Screens

For fast films, thermal neutron fluxes of about 10⁴4 nV (n/cm²-s) represent the minimum useful intensity for conventional transfer neutron radiography utilizing which one of the following conversion screens?

a. rhodium

b. dysprosium.

c. silver

d. gadolinium

22.

You normally use gadolinium direct exposure methods at your facility. You have available only one gadolinium screen, 36 cm x 43 cm (14 x 17 in.). One day, you wish to neutron radiograph a single very large object (100 cm x 30 cm [39 x 12 in.]) in a single exposure. Obtaining a widely divergent beam is no problem at this facility. Screens, however, are a problem. You are willing to sacrifice some image quality in order to avoid the expense of such a large vapor-deposited screen. To get the best results at the lowest cost you would:

a. use a thick plastic screen as a proton knock-on neutron converter

b. use an aluminum plate coated with gadolinium oxide paint.

c. use “no-screen” type film, with no converter but with approximately treble normal neutron exposures

d. use an europium screen

23.

Film principles, Properties, Use with Neutron Converter Screens

A 20 percent increase in exposure (Δ log E=0.08) for a given film convector combination results in a film density change from 2.3 to 2.7. The gradient of the characteristic curve is:

a. 0.2

b. 0.032

c. 2.0

d. 6.0.

24.

LiF, Zn S(Ag) neutron scintillators, which can be used as a fluoroscopic screen, emit blue light that:

a. is a good match for the spectral response of most films.

b. is a good match for the spectral sensitivity of the human eye

c. creates high screen brightness

d. creates high resolution in the image

25.

Which of the following facts are true concerning the use of a regular X-ray gadolinium₂0₂ S screen as a neutron converter?

a. the film is exposed by a combination of light and electrons generated initially at over 10 different energy levels.

b. the film is exposed mainly by blue light as for a typical LiF-ZnS (Ag) scintillator screen

c. the gamma discrimination is better than would be true for a gadolinium metal foil converter

d. the sharpness of the radiograph will usually be inferior if the rear scintillator face is photographed through a camera rather than imaged with an equal quality film placed adjacent to the rear of the screen

26.

Fluoroscopy-TV and Optical Systems

A practical video neutron-radiographic system could not be based on a:

a. boron converter

b. dysprosium converter.

c. gadolinium converter

d. lithium converter

27.

Gaseous Ionization Detectors

When using a gaseous proportional counter for neutron radiography, the principal ionization event utilizing thermal neutrons is due to which of the following?

a. photoelectric effect with certain gases

b. piezoelectric effect on the electrodes

c. gaseous discharge between the electrodes

d. alpha particles.

28.

Neutron Detectors

Which of the following types of detectors would be least likely to be used for neutron detection?

a.BF₃, proportional counter

b. NaI scintillation counter.

c. plastic scintillation counter

d. lithium-glass scintillation counter

29.

Neutrons may be detected and measured using a foil activation technique. A foil material suitable for detecting thermal neutrons with this technique is:

a. carbon

b. gold.

c. gadolinium

d. boron

30.

A boron trifluoride neutron counter is known as a proportional counter because:

a. the neutron cross section is proportional to the inverse of neutron energy

b. the neutron cross section is proportional to the inverse of neutron velocity

c. the electronic signal is proportional to the voltage applied to the system

d. the quantity of charge collected for a given amount of radiation is larger than, but proportional to, the original amount of ionization.

31.

Instrumentation

The output of most non-imaging neutron detectors is:

a. an electric signal.

b. an acoustic signal

c. a mechanical signal

d. a thermal signal

32.

Gaging and Control Processes

A gaging setup can distinguish 5% changes in the intensity of a transmitted neutron beam. If the average thickness of a sheet being gaged attenuates the neutron-beam intensity by a factor of 20 (~3 mean free paths), how small a change in thickness will be detectable?

a. 0.4%

b. 1.15%

c. 1.7%.

d. 4%

33.

A system of gaging in which the radiation is collimated and projected through a test item and the quantity of unabsorbed radiation is measured is referred to as the:

a. fluoresence method

b. absorption differential method

c. attenuation “build-up” method

d. transmission method.

34.

Generally, the sensitivity and accuracy of thickness gaging by reflection methods are:

a. superior to transmission gaging

b. superior to fluorescence methods

c. inferior to transmission gaging.

d. approximately the same as with transmission gaging

35.

PERSONNEL SAFETY AND RADIATION PROTECTION Exposure Hazards

Where isotopic sources are employed for field neutron radiographic applications, the radiation levels near the biological shield should not exceed:

a. 200 mR/h at the surface and 2 mR/h at 1 m (3.3 ft).

b. 700 mR/h at the surface and 10 mR/h at 1 m (3.3 ft)

c. 1 R/h at the surface and 20 mR/h at 1 m (3.3 ft)

d. none of the above

36.

Specific Neutron Hazards

Which of the following neutron personnel monitoring conditions is incorrect?

a. monitoring of thermal neutrons (<0.5 eV) does not pose a serious problem because the ready availability of a number of suitable detectors, such as the cadmium- or rhodium-covered personnel-monitoring films and LiF-6 thermoluminescent detectors

b. the detector should respond predominantly to the type of radiation that it is meant to monitor and its sensitivity to other types of radiation that may be simultaneously present should be minimal

c. intermediate energy neutron monitoring does not pose a serious problem because the many types of albedo dosimeters now in use are reasonably reliable due to the fairly linear response independent of the neutron spectrum.

d. none of the above

37.

Operation and Emergency Procedures

“Occupational dose” as applied to the exposure of an individual to radiation in a restricted area or in the course of employment in which the individual’s duties involve exposure to radiation shall:

a. not be deemed to include any exposure of an individual to radiation for the purpose of medical diagnosis or medical therapy of such an individual.

b. includes all radiation received by an individual from his work duties, medical diagnosis, dental, or medical therapy

c. includes only that radiation which he deems necessary to report

d. includes only those doses that exceed 5 R in any one year

38.

The rad, as used in USNRC Title 10, Chapter 1 CFR, Part 20, is a measure of the dose of any ionizing radiation to body tissue in terms of the energy absorbed per unit mass of the tissue. One rad is the dose corresponding to the absorption of how many joules (ergs) per gram of tissue.

a. 8.3 μJ (83.6 ergs) of energy

b. 10 μJ (100 ergs) of energy.

c. 9.3 μJ (93 ergs) of energy

d. 7.6 μJ (76.2 ergs) of energy

39.

An unrestricted area means:

a. any area where doctors and medical staff personnel are allowed to pass while on duty

b. any area established to perform radiographic operation usually roped off to 2 mR/h

c. any area used to store radioactive materials or radiation-producing equipment

d. any area to which access is not controlled by the licensee for purposes of protection of individuals from exposure to radiation and radioactive materials, and any area used for residential quarters.

40.

Units of radioactivity are commonly measured in terms of disintegrations per unit of time or in curies. One curie is:

a. 2.2 x 10³ disintegrations per second

b. 3.7 x 10⁶ disintegrations per second

c. 3.7 x 10¹⁰ disintegrations per second.

d. dependent on the type of isotope

41.

What is the maximum dose that a worker can be permitted to receive in a restricted area in any one calendar quarter?

a. 5 rems- whole body, head trunk, active blood-forming organs, lens of the eye, or gonads

b. 4 rads whole body, head trunk, active blood-forming organs, lens of the eye, or gonads

c. 3 rems whole body, head trunk, active blood-forming organs, lens of the eye, or gonads.

d. 1-1/4 rems whole body, head trunk, active blood-forming organs, the lens of the eye, or gonads

42.

THE RADIOGRAPHIC PROCESS Imaging Considerations – Sensitivity

According to the standard ASTM E-545, which of the following is an acceptable level of neutron radiographic sensitivity?

a. S = 10

b. S 15

c. R=5

d. R= 10.

43.

Contrast and Definition

Which of the following parameters do not directly affect radiographic definition?

a. focal spot or source size

b. density.

c. type of screen

d. radiation quality

44.

Film contrast refers to:

a. the density difference in two adjacent regions of the film

b. the steepness (slope) of the characteristic curve.

c. the ratio of X-ray or gamma-ray intensities transmitted by two selected portions of a specimen

d. minimum perceptible density change

45.

In general, the contrast of radiographic films (except those designed for use with fluorescent screens):

a. increases continuously with film density.

b. decreases as the density is increased

c. remains practically unchanged for different density levels

d. is inversely proportional to film density

46.

Specimens with uniform thickness and composition by definition have:

a. high subject contrast

b. good definition

c. high film contrast

d. low subject contrast.

47.

The sharpness of the outline in a radiographic image is referred to as:

a. definition.

b. sensitivity

c. latitude

d. contrast

48.

The poor radiographic definition could be the result of:

a. focal spot size

b. source film distance

c. poor film-screen contact

d. all of the above.

49.

Based on the characteristic curves of the films below, which film provides the highest contrast?

a. Film X

b. Film Y.

c. Film Z

d. cannot be determined from the curves

50.

Geometric Factors

When a given resolution is desired in a radiograph, a compromise must be made between attainable resolution and neutron flux at the image plane because:

a. a greater flux is available at the image plane in high-resolution work

b. the flux available at the image plane is directly proportional to the solid angle subtended by the aperture at that plane.

c. the flux at the image plane is less

d. the flux available at the image plane is inversely proportional to the solid angle subtended by the aperture at that plane

51.

Converter or intensifying screens are utilized in both direct and indirect photographic techniques. Which of the following is arranged from the highest to the lowest cross section for thermal neutrons?

a. gadolinium, dysprosium, indium, cadmium

b. samarium, cadmium, dysprosium, gold.

c. dysprosium, indium, gadolinium, silver

d. boron, samarium, cadmium, lithium-

52.

Converter or intensifying screens are utilized in both direct and indirect photographic techniques. Which of the following is arranged from the highest to the lowest cross section for thermal neutrons?

a. gadolinium, dysprosium, indium, cadmium

b. samarium, cadmium, dysprosium, gold.

c. dysprosium, indium, gadolinium, silver

d. boron, samarium, cadmium, lithium-

53.

Converter or intensifying screens are utilized in both direct and indirect photographic techniques. Which of the following is arranged from the highest to the lowest cross section for thermal neutrons?

a. gadolinium, dysprosium, indium, cadmium

b. samarium, cadmium, dysprosium, gold.

c. dysprosium, indium, gadolinium, silver

d. boron, samarium, cadmium, lithium-

54.

Intensifying Screens

Dy-164 has a cross-section of 2 700 10^-28m². (2 700 barns) for the 1.25-minute half-life activity, and 800 10^-28m² (800 barns) for the 140-minute half-life activity. Considering activation transfer neutron radiography in which there is minimal delay between foil neutron exposure and film contact, and assuming a long transfer period (12 hours), which of the following is true?

a. a greater film density could be obtained from a 20 MW-sec reactor pulse than from the same facility operated at 100 kW for 10⁴ seconds (2.78 hours)

b. the film density obtained from a 2 000 MW reactor pulse is approximately equal to that obtained from an operation of the same facility at 100 kW for 10³seconds (16.6 minutes)

c. if now a cadmium foil filter is put in the incident beam (epithermal neutron radiography instead of thermal) and the long 10⁴-second exposure is used first with dysprosium foil transfer and then with indium foil transfer, the indium transferred activity is greater for dysprosium.

d. none of the above

55.

Scattered Radiation

The problem of scatter in a hydrogenous object being radiographed can be reduced by:

a. increasing the L/D ratio

b. using the transfer technique

c. employing laminographic

d. placing a neutron-absorbing collimating grid between the object and the film.

56.

Source Factors

Given a neutron beam with an L/D of 250, a thermal flux of 10⁶ n/cm²-s, and a 36-43 cm (14-17 in.) exposure area, what is the geometric sharpness for a test object of 6 mm (0.25 in.) thick?

a. 0.01

b. 0.05

c. 0.001.

d. 0.005

57.

Indium-resonance neutrons:

a. are not used in conjunction with an indium converter

b. are never used in transfer radiography

c. are not used for reactor-fuel radiography

d. none of the above.

58.

Detection Media

Which of the following converters cannot be used for transfer neutron radiography?

a. indium

b. dysprosium

c. cadmium.

d. rhodium

59.

Cold neutrons can be detected with high efficiency, for imaging by:

a. ordinary gadolinium converters.

b. radiography film directly

c. special beryllium filters

d. both a and b

60.

The relative n/y ray sensitivity of metal screens that of converters is generally about scintillating-screen converters for direct exposure radiography.

a. two orders of magnitude greater than

b. one order of magnitude greater than

c. the same as

d. one order of magnitude less than.

61.

Exposure Curves

The contrast observed in a radiographic image is greater when:

a. the film density gradient is maximum.

b. the response of the human eye is logarithmic

c. one operates at the lowest portion of the D-Log E curve

d. one operates at the highest portion of the D-Log E curve

62.

Film Processing Darkroom Equipment and Chemicals

Which statement concerning darkroom equipment and chemicals is incorrect?

a. processing rooms should be supplied with filtered air, at a pressure above that of the outside

b. when the exposed film is placed in the developer, the solution penetrates the emulsion and begins to transform the exposed silver halide crystals to

c. vessels used for processing of films should not be metallic silver made from aluminum or tin because they could cause contamination and result in fog in the radiograph

d. the usefulness of a fixer solution is ended when it has lost its basicity.

63.

In automatic processing, over-replenishment of the fixer solution may result in:

a. poor fixation

b. insufficient hardening

c. failure of the film to be transported through the fixer rack

d. none of the above.

64.

Background Lighting

The contrast sensitivity of the human eye is greatest when the surroundings compared to the area of interest on a radiograph are:

a. about the same brightness.

b. of a lower brightness

c. of a higher brightness

d. brightness is not a factor in contrast sensitivity

65.

For best contrast sensitivity, the film viewing room should have lighting:

a. as dark as possible

b. of approximately 38 lumens

c. of approximately 70 lumens

d. as light as the area of interest in the film being reviewed.

66.

When reviewing film, background lighting should:

a. be virtually eliminated

b. not reflect on the film under examinations.

c. be carefully filtered

d. be approximately 20 lumens

67.

Density-Judging Radiographic Quality

Photographic density refers to the quantitative measure of film blackening. When no danger of confusion exists, photographic density is usually spoken of merely as “density.” Density is defined by the equation:

68.

Contrast

Radiographic contrast for neutron radiography is a function of the:

a. size and shape of the neutron source

b. length of the beam collimator

c. L/D ratio

d. gradient of the characteristic curve of the film and the neutron energy.

69.

Radiographic contrast in neutron radiography can sometimes be increased by the proper choice of converter foils. If a gadolinium foil were chosen in place of an indium foil, you might be seeking contrast enhancement from:

a. the increased cross section in the sample for lower energy neutrons.

b. the use of prompt rather than delayed emission of radiation

c. the generally thinner gadolinium foil

d. all of the above

70.

Definition

Standard ASTM E-545 uses a maximum of how many sensitivity indicators?

a. 2

b. 3

c. 4

d. 5

71.

Artifacts

The appearance of colored stains on a processed radiograph could be caused by:

a. neutralization of the acid in the fixer solution.

b. neutralization of the alkaline content in the fixer solution

c. acidification of the fixer solution

d. underdevelopment

72.

Prolonged washing of film in water above 68 °F has a tendency to:

a. crystallize the gelation

b. soften the gelation.

c. cause the yellow stain

d. cause the image to fade

73.

The ASTM beam purity indicator is designed primarily to indicate:

a. contrast.

b. sharpness

c. speed

d. all of the above

74.

The image quality indicator is generally made of:

a. the same material as that of the specimen being radiographed.

b. a more dense material than that of the specimen being radiographed

c. a material having a 10% greater density than the specimen being radiographed into account thickness changes

d. none of the above

75.

Exposure Calculations

You design a divergent collimator NR system on a given beam port such that the exposure area is 10 x 10 cm (4 x 4 in.), and the geometric unharness is 50 μ at 1 cm (0.4 in.) separation between detail and screen. Using the same neutron source beam tube, you now redesign for a 30 x 30 cm (12 x 12 in.) exposure area and a geometric unharness of 100 μ at 1 cm (0.4 in.). The larger aperture and divergence cause a flux depression at the source of a factor of 2 as compared with the first system. The new exposure time required when using gadolinium foil and Kodak SR film on a thin object is 300 seconds. Estimate the original source flux and exposure time.

a. 2 x 10^{11 n}/cm² -sec, 6 000 seconds

b. 2 x 10^12 n /cm² -sec, 600 seconds

c. 2 x 10¹³ ⁿ /cm² -sec, 300 seconds

d. 2x 10¹⁴ⁿ /cm² -sec, 30 seconds

76.

In order to provide the initial evaluation as to the practicality of a particular direct neutron radiograph exposure method, which term is not needed?

a. number of nuclei/cm³ of absorbing material

b. decay constant (0.693/ T_1/2, where T_1/2 is the half-life).

c. total cross-section of material (in cm)

d. material thickness (in cm)

77.

RADIOGRAPHIC TECHNIQUES Blocking and Filtering

A filter material commonly used in a neutron beam to improve the neutron-to-gamma ratio is

a. U-238

b. bismuth.

c. copper

d. lithium

78.

Multifilm Techniques

Which of the following is the most inclusive?

a. M film

b. single emulsion film

c. Class I film.

d. AA film

79.

Enlargement and Projection

With the normal divergent collimator, image magnification occurs as the spacing between the object plane and the detector plane increases. If L is the source-to-object distance, and t is the object-to-image plane distance, then the magnification is:

a. L/t

b. t/L

c. L/L-t

d. (L+t)/L.

80.

Autoradiography

A practical application of autoradiography subsequent to neutron activation is:

a. a study of hydrogen embrittlement of titanium

b. faded photograph restoration.

c. a study of the diffusion of boric acid in concrete samples

d. both b and c

81.

Flash Radiography

High-speed radiography can be best performed by:

a. autoradiography

b. in-motion radiography

c. laminographic

d. flash radiography using a pulsed neutron source.

82.

Fluoroscopy

One of the main disadvantages of a fluoroscopic system is:

a. extensive operator training required

b. high image brightness on the screen

c. flaw image enlargement

d. limited ability to see fine detail.

83.

Fluoroscopy possesses certain advantages over film radiography such as its:

a. attainable resolution is greater than with film

b. sensitivity is far greater than can be obtained with film

c. low cost and high speed.

d. none of the above

84.

Microradiography

Which of the following parameters has minimal or no effect on resolution when making a microradiograph?

a. the angular divergence of the neutron beam

b. the thickness of the object being investigated

c. the type of converter material and the converter screen thickness

d. the latitude of the photographic emulsion.

85.

Laminography (Tomography)

In tomography, the plane of the object that will be in focus is determined by the:

a. distance of the source from the object

b. ratio of the object-film distance to the object-source distance

c. position of the pivot point of the film-source mechanism relative to the object.

d. angle through which the film-source mechanism travels

86.

Gaging

Isotopic sources have certain advantages over radiation generators for gaging in that:

a. an isotopic source yield is stable over the short term, although it does decay with time.

b. these sources require more stringent regulation than accelerators to protect personnel

c. isotopic sources can be switched off with ease

d. none of these

87.

Real-Time Imaging

Which of the following is not associated with real-time neutron imaging?

a. optical coupling

b. television camera

c. intensifier tube

d. dysprosium foil.

88.

Image Analysis Techniques

Assuming 10° electrons associated with a particular feature of an image, the expected variation due to statistical consideration is:

a. 100 electrons

b. 500 electrons

c. 1 000 electrons.

d. 5 000 electrons

89.

Image Analysis Techniques

Assuming 10° electrons associated with a particular feature of an image, the expected variation due to statistical consideration is:

a. 100 electrons

b. 500 electrons

c. 1 000 electrons.

d. 5 000 electrons

90.

RADIOGRAPHIC INTERPRETATION Image-Object Relationships

The best standard for image-object relationship is:

a. a comparison standard.

b. a BPI standard

c. a penetrameter

d. a type A resolution standard

91.

Material Processing as It Affects the Use of Item and Test Results Material Considerations

Radiographic detection of small amounts of explosives in thick steel will give the best contrast if what kind of neutrons are used?

a. cold.

b. thermal

c. epithermal

d. the optimum resonance energy

92.

Compared to thermal neutrons, in crystalline materials, cold neutrons are:

a. scattered more and absorbed less

b. scattered less and absorbed more.

c. scattered less and absorbed less

d. scattered more and absorbed more

93.

Discontinuities: Their Causes and Effects

Particles of foreign material such as sand or slag that are embedded in the cast metal are indicative of the:

a. gas holes

b. buckles

c. rattails

d. inclusions.

94.

One lower limit of detectability of microporosity in materials can be caused by:

a. an L/D ratio that is too small and/or clumping of the grains of the developed film.

b. variation in the neutron source flux at the image plane

c. an excessively high L/D ratio

d. none of the above

95. Codes, Standards, Specifications, and Procedures

As stated in the “Standard Method for Determining Image Quality in Thermal Radiographic Testing,” ASTM E-545-75, which of the following statements are justification for preparing a process control radiograph for Verification of specified exposure and sensitivity requirements?

(1) The part setup does not provide for the location of image quality indicators to give adequate

(2) The part configuration necessitates a film-to-beam orientation which does not provide satisfactory density measurements for the calculation of exposure by collimated thermal neutrons.

(3) The size or setup of parts is such that the background film density variation across the film exceeds 5% (+2.5% variation from the numerical mean of 5 measurements).

(4) The part materials necessitate the use of a conversion screen that responds to neutrons of energies other than thermal in order to give adequate readings.

(5) The size or setup of parts is such that the object-scattered neutron level relative to background density, sensitivity, or facility-scattered neutron exposure requirements is cause for non-conformance.

a. (1), (2), and/or (3)

b. (2), (3), and/or (5)

c. (1), (2), and/or (4)

d. (1), (2), and/or (5)

Question 1 of 95

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A thermal neutron beam is extracted horizontally from a reactor. Neglecting to scatter by air or other materials in its path, what would you expect the beam path over the first 15 m (49 ft) to do?

Nature of Penetrating Radiation

Neutrons:

Which of the following is true for neutron radiographic conditions?

Interaction between Penetrating Radiation and Matter

When the mass absorption coefficient for neutrons is plotted as a function of the atomic number of the absorber, it presents a:?

You have to neutron radiograph an object that required visualization of very small hydrogenous details behind 76 mm (3 in.) of steel. The standard technique using a tangential beam on a reactor proves insufficient. What would be the recommended approach?

Which of the following statements is incorrect?

From the following penetrating radiations, which one can best be used to radiograph a cylinder of hydrocarbon plastic that is 50 mm (2 in.) in diameter in which we want to image embedded metal parts?

Following neutron capture in a gadolinium-foil converter, which of the following is emitted from the foil surface and interacts in the photographic emulsion to produce a high-resolution latent image?

A fact concerning the reciprocity law failure in neutron radiography is that:

The photographic latent image may be defined as that radiation-induced change in a grain or crystal that renders the grain readily susceptible to the chemical action of a developer. The material of the latent image itself is typical:

Track etch neutron imaging differs from dysprosium transfer imaging in which of the following ways?

Imaging by Fluorescent Materials

When fluorescent materials are employed for neutron radiographic imaging, reciprocity failure is often encountered. This is due to the fact that:

Imaging by Electronic Devices

Electron imaging devices invariably provide:

Substitution of gadolinium-oxysulfide for ZrS-Li°F as the input converter is an electronic imaging device will normally result in:

Radiometry

The “cadmium ratio” of a neutron refers to:

SOURCES OF NEUTRONS Neutron Sources-General Reactors

High-quality neutron radiographs are produced by reactor neutron sources because of the:

Accelerators

Which one of the following generators has a significant neutron yield at the low bombardment energies?

Isotopic Sources

The neutron-producing reaction of Cf-252 is:

Of the isotopic sources employed for neutron radiography, which of the following sources decays by the spontaneous fission process?

RADIATION DETECTORS Imaging Converter Screens

For fast films, thermal neutron fluxes of about 1044 nV (n/cm2-s) represent the minimum useful intensity for conventional transfer neutron radiography utilizing which one of the following conversion screens?

Film principles, Properties, Use with Neutron Converter Screens

A 20 percent increase in exposure (Δ log E=0.08) for a given film convector combination results in a film density change from 2.3 to 2.7. The gradient of the characteristic curve is:

LiF, Zn S(Ag) neutron scintillators, which can be used as a fluoroscopic screen, emit blue light that:

Which of the following facts are true concerning the use of a regular X-ray gadolinium202 S screen as a neutron converter?

Fluoroscopy-TV and Optical Systems

A practical video neutron-radiographic system could not be based on a:

Gaseous Ionization Detectors

When using a gaseous proportional counter for neutron radiography, the principal ionization event utilizing thermal neutrons is due to which of the following?

Neutron Detectors

Which of the following types of detectors would be least likely to be used for neutron detection?

Neutrons may be detected and measured using a foil activation technique. A foil material suitable for detecting thermal neutrons with this technique is:

A boron trifluoride neutron counter is known as a proportional counter because:

Instrumentation

The output of most non-imaging neutron detectors is:

Gaging and Control Processes

A gaging setup can distinguish 5% changes in the intensity of a transmitted neutron beam. If the average thickness of a sheet being gaged attenuates the neutron-beam intensity by a factor of 20 (~3 mean free paths), how small a change in thickness will be detectable?

A system of gaging in which the radiation is collimated and projected through a test item and the quantity of unabsorbed radiation is measured is referred to as the:

Generally, the sensitivity and accuracy of thickness gaging by reflection methods are:

PERSONNEL SAFETY AND RADIATION PROTECTION Exposure Hazards

Where isotopic sources are employed for field neutron radiographic applications, the radiation levels near the biological shield should not exceed:

Specific Neutron Hazards

Which of the following neutron personnel monitoring conditions is incorrect?

Operation and Emergency Procedures

“Occupational dose” as applied to the exposure of an individual to radiation in a restricted area or in the course of employment in which the individual’s duties involve exposure to radiation shall:

The rad, as used in USNRC Title 10, Chapter 1 CFR, Part 20, is a measure of the dose of any ionizing radiation to body tissue in terms of the energy absorbed per unit mass of the tissue. One rad is the dose corresponding to the absorption of how many joules (ergs) per gram of tissue.

An unrestricted area means:

Units of radioactivity are commonly measured in terms of disintegrations per unit of time or in curies. One curie is:

What is the maximum dose that a worker can be permitted to receive in a restricted area in any one calendar quarter?

THE RADIOGRAPHIC PROCESS Imaging Considerations – Sensitivity

According to the standard ASTM E-545, which of the following is an acceptable level of neutron radiographic sensitivity?

Contrast and Definition

Which of the following parameters do not directly affect radiographic definition?

Film contrast refers to:

In general, the contrast of radiographic films (except those designed for use with fluorescent screens):

Specimens with uniform thickness and composition by definition have:

The sharpness of the outline in a radiographic image is referred to as:

The poor radiographic definition could be the result of:

Based on the characteristic curves of the films below, which film provides the highest contrast?

Geometric Factors

When a given resolution is desired in a radiograph, a compromise must be made between attainable resolution and neutron flux at the image plane because:

Converter or intensifying screens are utilized in both direct and indirect photographic techniques. Which of the following is arranged from the highest to the lowest cross section for thermal neutrons?

Converter or intensifying screens are utilized in both direct and indirect photographic techniques. Which of the following is arranged from the highest to the lowest cross section for thermal neutrons?

Converter or intensifying screens are utilized in both direct and indirect photographic techniques. Which of the following is arranged from the highest to the lowest cross section for thermal neutrons?

Intensifying Screens

Scattered Radiation

The problem of scatter in a hydrogenous object being radiographed can be reduced by:

Source Factors

Given a neutron beam with an L/D of 250, a thermal flux of 106 n/cm2-s, and a 36-43 cm (14-17 in.) exposure area, what is the geometric sharpness for a test object of 6 mm (0.25 in.) thick?

Indium-resonance neutrons:

Detection Media

Which of the following converters cannot be used for transfer neutron radiography?

For fast films, thermal neutron fluxes of about 10⁴4 nV (n/cm²-s) represent the minimum useful intensity for conventional transfer neutron radiography utilizing which one of the following conversion screens?

Which of the following facts are true concerning the use of a regular X-ray gadolinium₂0₂ S screen as a neutron converter?

Given a neutron beam with an L/D of 250, a thermal flux of 10⁶ n/cm²-s, and a 36-43 cm (14-17 in.) exposure area, what is the geometric sharpness for a test object of 6 mm (0.25 in.) thick?