ASNT Neutron Radiography 2

Question 1

What is the approximate kinetic energy range for thermal neutrons used in neutron radiography?

Accepted Answer

Below 0.5 eV

Answer

Thermal neutrons have energies approximately equal to room-temperature kinetic energy, typically below 0.5 eV (around 0.025 eV at room temperature), which gives them high interaction cross-sections with many nuclides.

Question 2

In the transfer (indirect) neutron radiography method, what is the purpose of using an activation foil?

Accepted Answer

To become radioactive during exposure and later expose film away from the neutron source

Answer

In the transfer method, a foil (commonly indium or dysprosium) is activated by neutron bombardment alongside the specimen; the foil is then placed against film in a low-background area to produce the radiographic image.

Question 3

What major radiation safety hazard is unique to neutron radiography compared to conventional X-radiography?

Accepted Answer

Induced radioactivity in inspected components and equipment

Answer

Neutron bombardment can induce radioactivity in the specimen and surrounding structural materials through neutron activation, requiring careful handling and decay waiting periods after inspection.

Question 4

Which isotope produces prompt gamma radiation with a large thermal neutron cross-section and is sometimes used in real-time neutron imaging scintillator screens?

Accepted Answer

Boron-10

Answer

Boron-10 has a very large thermal neutron capture cross-section (~3,840 barns) and produces detectable charged particles; boron-loaded scintillators exploit this reaction for real-time neutron imaging.

Question 5

What is the term for the image quality indicator (IQI) used to verify sensitivity and resolution in neutron radiography?

Accepted Answer

Penetrameter

Answer

A penetrameter (also called an image quality indicator or IQI) is placed on the source side of the object to verify that the radiograph meets minimum sensitivity requirements, as described in ASTM E748.

ASNT - American Society for Nondestructive Testing, Inc. Practice Test

ASNT - American Society for Nondestructive Testing, Inc. Practice Test

ASNT Neutron Radiography 2