NAC459.3255. Compliance with requirements for summation of external and internal doses.

     1. If a licensee is required to monitor a person pursuant to subsections 1 and 2 of NAC 459.339, the licensee shall demonstrate compliance with the limits set forth in NAC 459.325 by adding external and internal doses. The licensee may demonstrate compliance with the requirements for summation of external and internal doses by meeting one of the conditions specified in subsection 2 and the conditions specified in subsections 3 and 4. The lens dose equivalent and the dose equivalents for the skin and the extremities are not required to be included in the summation, but are subject to separate limits set forth in NAC 459.325. If a licensee or registrant is required to monitor a person pursuant to subsection 1 of NAC 459.339 only or pursuant to subsection 2 of NAC 459.339 only, the summation of the doses is not required.

     2. If the only intake of radionuclides is by inhalation, the limit for the total effective dose equivalent is not exceeded if the deep-dose equivalent divided by the limit for the total effective dose equivalent, and one of the following, does not exceed unity:

     (a) The sum of the fractions of the annual limit on intake by inhalation for each radionuclide.

     (b) The total number of derived air concentration-hours for all radionuclides, divided by 2,000.

     (c) The sum of the committed effective dose equivalents to all significantly irradiated organs or tissues, calculated from bioassay data using appropriate biological models and expressed as a fraction of the annual limit. For the purposes of this subsection, an organ or tissue shall be deemed to be irradiated significantly if, for that organ or tissue, the product of the weighting factors and the committed dose equivalent, per unit intake, is greater than 10 percent of the maximum weighted value of the committed dose equivalent, per unit intake for any organ or tissue.

     3. If a person who receives an occupational exposure also receives an intake of radionuclides by oral ingestion in an amount greater than 10 percent of the applicable annual limit on intake by oral ingestion, the licensee shall account for this intake and include it in demonstrating compliance with the limits set forth in NAC 459.325.

     4. Except as otherwise provided in this subsection, the licensee shall evaluate and, to the extent practical, account for the intake of radiation through wounds or absorption through the skin. Any intake through intact skin is not required to be evaluated or accounted for pursuant to this subsection.

     (Added to NAC by Bd. of Health, eff. 1-18-94; A by Dep’t of Human Resources by R137-01, 5-30-2003)