Section 650. Compliance with requirements for summation of external and internal doses

A. If the licensee is required to monitor under subdivisions 1 and 2 of 12VAC5-481-760, the licensee shall demonstrate compliance with the dose limits by summing external and internal doses. If the licensee is required to monitor only under subdivision 1 of 12VAC5-481-760 or only under subdivision 2 of 12VAC5-481-760, then summation is not required to demonstrate compliance with the dose limits. The licensee may demonstrate compliance with the requirements for summation of external and internal doses by meeting one of the conditions specified in subsections B, C, and D of this section. The dose equivalents for the lens of the eye, the skin, and the extremities are not included in the summation, but are subject to separate limits.

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

1. The sum of the fractions of the inhalation ALI for each radionuclide,

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

3. The sum of the calculated 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 requirement, an organ or tissue is deemed to be significantly irradiated if, for that organ or tissue, the product of the weighting factors and the committed dose equivalent per unit intake is greater than 10% of the maximum weighted value of the committed dose equivalent per unit intake of any organ or tissue.

C. Intake by oral ingestion. If the occupationally exposed individual also receives an intake of radionuclides by oral ingestion greater than 10% of the applicable oral ALI, the licensee shall account for this intake and include it in demonstrating compliance with the limits.

D. Intake through wounds or absorption through skin. The licensee shall evaluate and to the extent practical account for intakes through wounds or skin absorption. The intake through intact skin has been included in the calculation of DAC for hydrogen-3 and does not need to be evaluated.

Historical Notes

Derived from Volume 22, Issue 25, eff. September 20, 2006; amended, Virginia Register Volume 24, Issue 18, eff. June 12, 2008; Volume 32, Issue 24, eff. August 25, 2016.

Statutory Authority

§ 32.1-229 of the Code of Virginia.