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Rt practice questions

38 questions from the nondestructive testing (level ii) practice test.

Rt practice test

10 questions, graded as you go, with the reason for every answer. No sign-up.

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Sample questions

What is the approximate half-life of iridium-192?

  1. 30 days
  2. 120 days
  3. 74 days
  4. 5.3 years
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C. 74 days

Ir-192 has a half-life of about 74 days, so a source loses half its activity roughly every two and a half months and exposure times must be recalculated often. A half-life of 5.3 years belongs to cobalt-60 and about 120 days to selenium-75.

Reference: ASNT Level II RT study topic: isotope characteristics

Why is cobalt-60 chosen instead of iridium-192 for radiographing very thick steel sections?

  1. Its half-life is much shorter
  2. Its source capsule is very much smaller
  3. Its gamma rays have much higher energy
  4. Its radiation needs no shielding
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C. Its gamma rays have much higher energy

Co-60 emits gamma rays of about 1.17 and 1.33 MeV, far more penetrating than the lower-energy Ir-192 spectrum, so it suits steel several inches thick. The same high energy means Co-60 needs much heavier shielding, not less.

Reference: ASNT Level II RT study topic: isotope selection

The IQI cannot be placed on the source side of a pipe weld, so it is placed on the film side. How must this be shown on the radiograph under ASME Section V?

  1. A lead letter B beside the IQI
  2. Two IQIs placed side by side
  3. A note on the report only
  4. A lead letter F beside the IQI
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D. A lead letter F beside the IQI

A film-side IQI is identified by a lead letter F placed next to it, so the interpreter knows the IQI was in the less demanding position. The lead letter B is something different: it goes on the back of the cassette to check for backscatter.

Reference: ASME BPVC Section V, Article 2, IQI placement

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