Current through 2024-38, September 18, 2024
A. For purposes
of assessing dose used to determine compliance with occupational dose
equivalent limits, the licensee or registrant shall, when required pursuant to
D.1502, take suitable and timely measurements of:
(1) Concentrations of radioactive materials
in air in work areas; or
(2)
Quantities of radionuclides in the body; or
(3) Quantities of radionuclides excreted from
the body; or
(4) Combinations of
these measurements.
B.
Unless respiratory protective equipment is used, as provided in D.1703, or the
assessment of intake is based on bioassays, the licensee or registrant shall
assume that an individual inhales radioactive material at the airborne
concentration in which the individual is present.
C. When specific information on the physical
and biochemical properties of the radionuclides taken into the body or the
behavior of the material in an individual is known, the licensee or registrant
may:
(1) Use that information to calculate the
committed effective dose equivalent, and, if used, the licensee or registrant
shall document that information in the individual's record; and
(2) Upon prior approval of the Agency, adjust
the DAC or ALI values to reflect the actual physical and chemical
characteristics of airborne radioactive material, for example, aerosol size
distribution or density; and
(3)
Separately assess the contribution of fractional intakes of Class D, W, or Y
compounds of a given radionuclide to the committed effective dose equivalent
(CEDE). See Appendix B.
D. If the licensee or registrant chooses to
assess intakes of Class Y material using the measurements given in D.1204.A(2)
or (3), the licensee or registrant may delay the recording and reporting of the
assessments for periods up to seven months, unless otherwise required by D.2202
or D.2203. This delay permits the licensee or registrant to make additional
measurements basic to the assessments.
E. If the identity and concentration of each
radionuclide in a mixture are known, the fraction of the DAC applicable to the
mixture for use in calculating DAC-hours shall be either:
(1) The sum of the ratios of the
concentration to the appropriate DAC value, that is, D, W, or Y, from Appendix
B for each radionuclide in the mixture; or
(2) The ratio of the total concentration for
all radionuclides in the mixture to the most restrictive DAC value for any
radionuclide in the mixture.
F. If the identity of each radionuclide in a
mixture is known, but the concentration of one or more of the radionuclides in
the mixture is not known, the DAC for the mixture shall be the most restrictive
DAC of any radionuclide in the mixture.
G. When a mixture of radionuclides in air
exists, a licensee or registrant may disregard certain radionuclides in the
mixture if:
(1) The licensee or registrant
uses the total activity of the mixture in demonstrating compliance with the
dose limits in D.6 and in complying with the monitoring requirements in
D.1502.B, and
(2) The concentration
of any radionuclide disregarded is fewer than 10 percent of its DAC,
and
(3) The sum of these
percentages for all of the radionuclides disregarded in the mixture does not
exceed 30 percent.
H.
(1) In order to calculate the committed
effective dose equivalent, the licensee or registrant may assume that the
inhalation of one ALI, or an exposure of 2,000 DAC-hours, results in a
committed effective dose equivalent of 5 rem (0.05 Sv) for radionuclides that
have their ALIs or DACs based on the committed effective dose
equivalent.
(2) When the ALI (and
the associated DAC) is determined by the non-stochastic organ dose limit of 50
rem (0.5 Sv), the intake of radionuclides that would result in a committed
effective dose equivalent of 5 rem (0.05 Sv), (the stochastic ALI) is listed in
parentheses in Table I of Appendix B to Part D. In this case, the licensee or
registrant may, as a simplifying assumption, use the stochastic ALIs to
determine committed effective dose equivalent. However, if the licensee or
registrant uses the stochastic ALIs, the licensee or registrant must also
demonstrate that the limit in D.1201.A(1)(b) is met.
