Alert

Due to a lapse in appropriations, the NRC has ceased normal operations. However, excepted and exempted activities necessary to maintain critical health and safety functions—as well as essential progress on designated critical activities, including those specified in Executive Order 14300—will continue, consistent with the OMB-Approved NRC Lapse Plan.

Health Physics Questions and Answers - Question 146

Question 146: The term "not present," which is defined in paragraph 5 of the Note (concerning mixtures of radionuclides) following Appendix B of the old Part 20, is not defined in the corresponding "Note" in the revised Part 20. Does this definition from the old Part 20, which indicates when a radionuclide may be considered as not present in a mixture, continue to apply in the revised Part 20?

Answer: No. Nothing in the old Part 20 (§§20.1-20.601) applies in the revised Part 20 (§§20.1001-20.2401). This definition of "not present" is not included in the revised Part 20; however, 10 CFR 20.1204 (g) stipulates the conditions under which licensees may disregard certain radionuclides in a mixture when determining internal dose. See the answer to the related Question 121 for clarification of 10 CFR 20.1204 (g).

(References: Appendix B, 10 CFR 20.1204)

Page Last Reviewed/Updated Tuesday, November 07, 2017