Current through September 17, 2024
Licensees must determine the internal dose as follows.
008.01
TIMELY
MEASUREMENTS. For purposes of assessing dose used to determine
compliance with occupational dose equivalent limits, the licensee must, when
required under 180 NAC
4-022 take suitable and timely
measurements of:
(A) Concentrations of
radioactive materials in air in work areas; or
(B) Quantities of radionuclides in the body;
or
(C) Quantities of radionuclides
excreted from the body; or
(D)
Combinations of these measurements.
008.02
INHALATION
CONCENTRATION. Unless respiratory protective equipment is used, as
provided in 180 NAC
4-028 or the assessment of intake is
based on bioassays, the licensee must assume that an individual inhales
radioactive material at the airborne concentration in which the individual is
present.
008.03
ADDITIONAL CONSIDERATIONS. When specific information
on the physical and biochemical properties of the radionuclides taken into the
body or the behavior or the material in an individual is known, the licensee
may:
(A) Use that information to calculate
the committed effective dose equivalent, and, if used, the licensee must
document that information in the individual's record; and
(B) Upon prior approval of the Department,
adjust the derived air concentration (DAC) or annual limit on intake (ALI)
values to reflect the actual physical and chemical characteristics of airborne
radioactive material, for example, aerosol size distribution or density;
and
(C) Separately assess the
contribution of fractional intakes of Class D, W, or Y compounds of a given
radionuclide to the committed effective dose equivalent. See Appendix 4-B of
180 NAC 4.
008.04
CLASSY MATERIAL INTAKE ASSESSMENT. If the licensee
chooses to assess intakes of Class Y material using the measurements given in
180 NAC 4-008.01(B) or (C), the licensee may delay the recording and reporting
of the assessments for periods up to seven months, unless otherwise required by
180 NAC
4-058 or
4-059. This delay permits the licensee
to make additional measurements basic to the assessments.
008.05
KNOWN NUCLIDES AND
CONCENTRATION. If the identity and concentration of each
radionuclide in a mixture are known, the fraction of the derived air
concentration (DAC) applicable to the mixture for use in calculating derived
air concentration (DAC)-hours must be either:
(A) The sum of the ratios of the
concentration to the appropriate derived air concentration (DAC) value, D, W,
or Y, from Appendix 4-B of 180 NAC 4 for each radionuclide in the mixture;
or
(B) The ratio of the total
concentration for all radionuclides in the mixture to the most restrictive
derived air concentration (DAC) value for any radionuclide in the
mixture.
008.06
KNOWN NUCLIDES. 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 derived air concentration (DAC)
for the mixture must be the most restrictive derived air concentration (DAC) of
any radionuclide in the mixture.
008.07
MIXTURE OF
NUCLIDES. When a mixture of radionuclides in air exists, a
licensee may disregard certain radionuclides in the mixture if:
(A) The licensee uses the total activity of
the mixture in demonstrating compliance with the dose limits in 180 NAC
4-005 and in complying with the
monitoring requirements in 180 NAC
4-022;
(B) The concentration of any radionuclide
disregarded is less than 10% of its derived air concentration (DAC);
and
(C) The sum of these
percentages for all of the radionuclides disregarded in the mixture does not
exceed 30%.
008.08
DETERMINING COMMITTED EFFECTIVE DOSE EQUIVALENT.
Committed effective dose equivalent must be determined as follows:
(A) In order to calculate the committed
effective dose equivalent, the licensee may assume that the inhalation of one
annual limit on intake (ALI), or an exposure of 2,000 derived air concentration
(DAC)-hours, results in a committed effective dose equivalent of 0.05 Sv (5
rem) for radionuclides that have their annual limit on intake (ALI)s or derived
air concentration (DAC)s based on the committed effective dose equivalent;
and
(B) For an annual limit on
intake (ALI), and the associated derived air concentration (DAC) determined by
the nonstochastic organ dose limit of 0.5 Sv (50 rem), the intake of
radionuclides that would result in a committed effective dose equivalent of
0.05 Sv (5 rem), the stochastic annual limit on intake (ALI) is listed in
parentheses in Table I of Appendix 4-B of 180 NAC 4. The licensee may, as a
simplifying assumption, use the stochastic annual limit on intake (ALI) to
determine committed effective dose equivalent. However, if the licensee uses
the stochastic annual limit on intake (ALI), the licensee must also demonstrate
that the limit in 180 NAC 4-005.01(A)(ii) is met.
