StacksVerified U.S. regulatory reference

10 CFR §39.41

Verified against eCFR.gov as of June 20, 2026View official text on eCFR.gov ↗
  1. (a)A licensee may use a sealed source for use in well logging applications if—
    1. (1)The sealed source is doubly encapsulated;
    2. (2)The sealed source contains licensed material whose chemical and physical forms are as insoluble and nondispersible as practical; and
    3. (3)Meets the requirements of paragraph (b), (c), or (d) of this section.
  2. (b)For a sealed source manufactured on or before July 14, 1989, a licensee may use the sealed source, for use in well logging applications if it meets the requirements of USASI N5.10-1968, “Classification of Sealed Radioactive Sources,” or the requirements in paragraph (c) or (d) of this section.
  3. (c)For a sealed source manufactured after July 14, 1989, a licensee may use the sealed source, for use in well logging applications if it meets the oil-well logging requirements of ANSI/HPS N43.6-1997, “Sealed Radioactive Sources—Classification.”
  4. (d)For a sealed source manufactured after July 14, 1989, a licensee may use the sealed source, for use in well logging applications, if—
    1. (1)The sealed source's prototype has been tested and found to maintain its integrity after each of the following tests:
      1. (i)Temperature. The test source must be held at −40 °C for 20 minutes, 600 °C for 1 hour, and then be subject to a thermal shock test with a temperature drop from 600 °C to 20 °C within 15 seconds.
      2. (ii)Impact test. A 5 kg steel hammer, 2.5 cm in diameter, must be dropped from a height of 1 m onto the test source.
      3. (iii)Vibration test. The test source must be subject to a vibration from 25 Hz to 500 Hz at 5 g amplitude for 30 minutes.
      4. (iv)Puncture test. A 1 gram hammer and pin, 0.3 cm pin diameter, must be dropped from a height of 1 m onto the test source.
      5. (v)Pressure test. The test source must be subject to an external pressure of 1.695 × 10 7 pascals [24,600 pounds per square inch absolute].
  5. (e)The requirements in paragraphs (a), (b), (c), and (d) of this section do not apply to sealed sources that contain licensed material in gaseous form.
  6. (f)The requirements in paragraphs (a), (b), (c), and (d) of this section do not apply to energy compensation sources (ECS). ECSs must be registered with the Commission under § 32.210 of this chapter or with an Agreement State.