RT 2 Final NDT Flashcards

Questions and Answers

Stringers would normally appear in:

gas state

solid material

bar product (correct)

liquid form

What is evaluation?

The act of determining if an indication is acceptable or unacceptable in relation to the acceptance standard.

Which of the following is a typical weld discontinuity?

incomplete fusion

crack

slag (correct)

porosity

How does the visibility of a particular penetrameter hole on the radiograph relate to a discontinuity?

The same size may or may not be visible depending on the orientation of the discontinuity. Signup and view all the answers

Geometric unsharpness will decrease when:

A longer source to film distance is used or a smaller source size is used. Signup and view all the answers

What is the purpose of a collimator?

To decrease the radiation in unwanted directions. Signup and view all the answers

What is subject contrast?

The amount of radiation penetration differences between two areas of the same radiographic specimen. Signup and view all the answers

If a plate weld is exposed using a 15" source to film distance for 4.5 minutes, what time should the exposure be shot to maintain the same overall density if the source to film distance is moved to 12"?

2.8 minutes. Signup and view all the answers

What is the advantage of having a source with a high specific activity?

Lower unsharpness. Signup and view all the answers

What will the placement of a thin copper filter across the beam exit point of an x-ray tube serve to do?

Remove low energy x-rays. Signup and view all the answers

X-rays are produced when electrons:

Bend around the nucleus and release energy due to the breaking action. Signup and view all the answers

What would the new exposure time be if the source is moved from 10" to 15" with an initial exposure of 3.5 minutes?

7.9. Signup and view all the answers

The speed of film used in a radiograph will normally depend on:

The part material thickness. Signup and view all the answers

When a bar is drawn from a billet cut from an ingot, what inclusion may cause?

Stinger. Signup and view all the answers

Which of the following weld processes would not produce slag in a weld?

GMAW Signup and view all the answers

When the velocity of the electrons traveling from the cathode to the target increases, what happens?

The energy level of the photons will increase. Signup and view all the answers

Which of the following would be used for determining the spatial resolution of a digital system?

Line pair gauge Signup and view all the answers

Of the following multiple choices, which helps to reduce radiation exposure?

all of the above Signup and view all the answers

If a Se-75 source is used with a 120 day half-life and the source was initially 100 curies, what is the intensity after 600 days?

3.1 Ci. Signup and view all the answers

What are the two processes of photon decay?

Compton scatter and photoelectric effect Signup and view all the answers

Which of the following densities of an IQI would be acceptable for a weld showing a minimum density of 2.21 and a maximum of 3.38? (-15% + 30%)

2.6 Signup and view all the answers

What is the purpose of the developer when developing radiographic film?

Turns the exposed silver bromide crystal to black metallic silver. Signup and view all the answers

How do x-ray tubes vary?

They vary in average energy levels due to the type of voltage such as AC, half wave rectified AC or full wave rectified AC. Signup and view all the answers

Which of the following would offer notice of radiation and help to reduce the radiographer's total exposure dose?

Survey meter Signup and view all the answers

What are the characteristics of high frequency X-ray photons?

They will have short wavelengths and high penetrating characteristics. Signup and view all the answers

Half Value Layer is defined as:

The amount of material needed to reduce the radiation on the source side to one half that on the opposite side. Signup and view all the answers

Where is the density of the IQI taken when using a 'hole' or plaque type IQI?

Next to the applicable hole required for the radiograph. Signup and view all the answers

What is the advantage of a source with a high specific activity?

It will provide a lower unsharpness value than a source with lower specific activity at the same sources to detector distance. Signup and view all the answers

Shrink would normally appear in:

Castings. Signup and view all the answers

What happens to scatter radiation as energy decreases?

It will increase. Signup and view all the answers

What is the minimum number of half value layers of lead needed to reduce a 250 mR intensity to or below 10 mR?

5 half value layers. Signup and view all the answers

What could cause a dark image of the lead letter 'B' on the radiograph?

Scatter from the lead letter B. Signup and view all the answers

Why are lead screens used in film cassettes during radiographic exposure?

To absorb the scattered radiation and increase the film density by intensifying the primary radiation. Signup and view all the answers

What is the lowest level of acute exposure that would be detectable in the blood?

30 Rem. Signup and view all the answers

Lack of penetration will occur in a:

Weld. Signup and view all the answers

One roentgen of x-ray or gamma radiation is equal to:

1 rem exposure. Signup and view all the answers

An example of a false indication would be:

Light strike from a hole in the cassette. Signup and view all the answers

An example of a non-relevant indication would be:

Machined keyway. Signup and view all the answers

If the initial intensity is 175 mR/hr and the intensity needs to be reduced to 2 mR/hr, what thickness of lead would be needed if the HVL is 0.20?

1.29". Signup and view all the answers

How long should an exposure be taken with an Ir-192 source for 5 minutes using a 50-Curie source that is now down to 35 curies?

7.1 minutes. Signup and view all the answers

Which of the following will have an effect on the final geometric unsharpness?

The thickness of the specimen to be examined. Signup and view all the answers

Inadequate source to part distance in the radiographic setup may cause:

Increase the penumbra around the images on the film. Signup and view all the answers

What is pipe found in an ingot considered?

Inherent discontinuity. Signup and view all the answers

If excessive energy is used to expose a part, what will be the result?

Low contrast of the final image. Signup and view all the answers

Of the following sources of radiation, which has the highest energy level?

Co-60 Signup and view all the answers

Lamination would normally appear in:

Plate. Signup and view all the answers

Where will a crater crack appear?

At the stopping point of a weld pass. Signup and view all the answers

The ability to discern the density differences from one area on an x-ray to the adjacent area is called:

Radiographic contrast. Signup and view all the answers

What is interpretation in the context of radiography?

The act of determining what causes an indication. Signup and view all the answers

Which of the following would be used to determine the final evaluation of a single pore of porosity?

Diameter of the porosity Signup and view all the answers

What is the tenth value layer?

Reduce the radiation intensity to 1/10th of the initial value. Signup and view all the answers

How does X-radiation differ from gamma radiation?

By the origin of the radiation. Signup and view all the answers

If the radiographer is in a 250 mR/hr radiation area 35 feet from the source, where will the 2 mR/hr boundary be if two half-value layers are placed between the source and the survey meter?

196 feet. Signup and view all the answers

Fast speed film will:

Have larger silver grains. Signup and view all the answers

What does the inverse square law state?

If the distance from the radiation source is doubled, then intensity is reduced to 1/4 of the original intensity. Signup and view all the answers

What does 2-2T penetrameter sensitivity require?

A penetrameter thickness that is 2% of the part thickness and a hole diameter that is 2 times the penetrameter thickness is clearly discernable on the radiographic image. Signup and view all the answers

When a photon knocks an electron out of orbit and gives its remaining energy to the electron in the form of speed, what is this process called?

Photoelectric effect. Signup and view all the answers

Uneven cooling of a material may cause:

Cracking. Signup and view all the answers

Study Notes

NDT Concepts and Definitions

Stringers are typically found in bar products, indicating specific structural components.
Evaluation involves assessing whether indications meet acceptance standards, crucial for quality control.
Weld Discontinuity often includes slag, which can interfere with the integrity of welds.

Radiography Fundamentals

Penetrameter visibility relates to discontinuities—size alone does not guarantee visibility, orientation matters.
Geometric unsharpness decreases with a longer source-to-film distance or smaller source size.
A collimator minimizes radiation scatter in undesired directions, enhancing image clarity.

Radiation and Film Exposure

Subject Contrast measures radiation penetration differences, essential for evaluating radiographic specimens.
A change in source-to-film distance impacts exposure time needed to maintain consistent density; for a shift from 15" to 12", time adjusts to 2.8 minutes.
High specific activity sources yield lower unsharpness, improving image quality and clarity.

X-ray Production and Safety

X-rays are generated when electrons bend near nuclei, releasing energy; critical for understanding imaging techniques.
Filters like copper remove low-energy X-rays, contributing to clearer radiographic images.
Radiation exposure reduction strategies include optimizing time, distance, and shielding.

Intensity and Half-Life Calculations

For a Se-75 source with a 120-day half-life starting at 100 curies, the intensity after 600 days is approximately 3.1 Ci.
Radiation intensity reduction is quantified by the Half Value Layer (HVL)—material needed to halve the radiation on one side.

Imaging Quality Indicators

Densitometry in IQI (Image Quality Indicators) assesses acceptable density ranges, ensuring the integrity of weld visualizations.
Developer solutions convert exposed silver bromide crystals to black metallic silver, essential for film processing.

X-ray Characteristics and Effects

High frequency X-ray photons feature short wavelengths, which correlate with their high penetration abilities.
Sources with higher energy levels, such as Co-60, have a greater impact on imaging quality and radiation risks.
Scatter radiation trends upward as energy decreases, affecting imaging integrity.

Radiographic Conditions

Weld lack of penetration can critically affect structural integrity, often inspection points.
Inadequate source-to-part distance can increase penumbra, impacting image clarity.
Cracking may result from uneven material cooling, a concern in material integrity assessments.

Evaluation and Interpretation

Interpretation refers to assessing the causes of indications, vital in identifying flaws.
Density differences assessment across radiographic images is known as radiographic contrast.

Special Cases in Radiography

Specific measurements such as the tenth value layer, which reduces intensity to one-tenth, are critical for understanding radiation safety dynamics.
False indications can arise from light strikes or imperfections, complicating readings.
A survey meter assists in monitoring radiation exposure, crucial for ensuring safety during inspections.

Additional Points

Fast speed film offers larger silver grains, enhancing image capture under various conditions.
The inverse square law indicates intensity reduction at doubled distances, fundamental for safety and operational protocols in radiography.

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Description

Test your knowledge on Non-Destructive Testing with these flashcards. This quiz covers terminology and concepts essential for evaluating welds and indications in NDT. Perfect for students and professionals preparing for the RT 2 exam.