Current through Register Vol. 46, No. 12, March 20, 2024
(a)
Occupational dose limits for adults.
(1)
Except for planned special exposures pursuant to subdivision (f) of this
section, no person shall transfer, receive, possess or use any radiation source
so as to cause any individual adult to receive an occupational dose from all
sources of radiation that exceeds any of the following limits:
(i) an annual limit, which is the more
limiting of:
(a) a total effective dose
equivalent equal to 0.05 Sv (5 rem); or
(b) the sum of the deep dose equivalent and
the committed dose equivalent to any individual organ or tissue, other than the
lens of the eye, equal to 0.50 Sv (50 rem);
(ii) annual limits to the lens of the eye, to
the skin, and to the extremities which are:
(a) an eye dose equivalent of 0.15 Sv (15
rem); and
(b) a shallow dose
equivalent of 0.50 Sv (50 rem) to the skin or to any extremity.
(2) Doses received in
excess of the annual limits, including doses received during accidents,
emergencies, and planned special exposures must be subtracted from the limits
for planned special exposures that the individual may receive during the
current year and during the individual's lifetime. (See paragraph [f][5] of
this section.)
(3) The assigned
deep dose equivalent and shallow dose equivalent shall be for the portion of
the body receiving the highest exposure. If an individual's monitoring device
was not in the region of highest potential exposure, or the results of
individual monitoring are unavailable, the deep dose equivalent, eye dose
equivalent and shallow dose equivalent may be assessed from surveys or other
radiation measurements for the purpose of demonstrating compliance with the
occupational dose limits.
(4)
Derived air concentration (DAC) and annual limit on intake (ALI) values are
presented in Appendix A-13 of section
38.41 of
this Part (rule), and may be used to determine the individual's dose and to
demonstrate compliance with the occupational dose limits.
(5) Notwithstanding the annual dose limits,
the licensee shall limit the soluble uranium intake by an individual to 10
milligrams in a week. (See footnote 3 of Appendix A-13 of section
38.41 of
this Part [rule].)
(6) The licensee
or registrant shall reduce the dose that an individual may be allowed to
receive in the current year by the amount of occupational dose received while
employed by any other person. (See subdivision [e]of this section.)
(b) Compliance with requirements
for summation of external and internal dose.
(1) Requirements for summation of external
and internal doses. If the licensee or registrant is required to monitor
pursuant to both subdivisions (a) and (b) of section
38.24 of
this Part (rule), the licensee or registrant shall demonstrate compliance with
the dose limits by summing external and internal doses. If the licensee or
registrant is required to monitor only pursuant to section
38.24(a)
or only pursuant to section
38.24(b)
of this Part (rule), then summation is not required in order to demonstrate
compliance with the dose limits. The licensee or registrant may demonstrate
compliance with the requirements for summation of external and internal doses
by meeting one of the conditions specified in paragraph (2) of this
subdivision, and the conditions in paragraphs (3) and (4) of this subdivision.
The dose equivalents for the lens of the eye, the skin, and the extremities are
not to be included in the summation, but are subject to separate
limits.
(2) 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:
(i) the sum of the
fractions of the inhalation ALI for each radionuclide; or
(ii) the total number of derived air
concentrations-hours (DAC-hours) for all radionuclides divided by 2,000;
or
(iii) the sum of the calculated
committed effective dose equivalents to all significantly irradiated organs or
tissues (T) calculated from bioassay data using appropriate biological models
and expressed as a fraction of the annual limit. For 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, W
T, and the committed dose equivalent, H
T,50, per unit intake is greater than 10 percent of the
maximum weighted value of H 50, that is, W
TH T,50 per unit intake for any
organ or tissue.
(3)
Intake by oral ingestion. If the occupationally exposed individual also
receives an intake of radionuclides by oral ingestion greater than 10 percent
of the applicable oral ALI, the licensee or registrant shall account for this
intake and include it in demonstrating compliance with the limits.
(4) Intake through wounds or absorption
through skin. The licensee or registrant shall evaluate and 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 or accounted for pursuant to this paragraph.
(c) Determination of external dose from
airborne radioactive material.
(1) Licensees
shall, when determining the dose from airborne radioactive material, include
the contribution to the deep dose equivalent, eye dose equivalent, and shallow
dose equivalent from external exposure to the radioactive cloud (see footnotes
1 and 2 of Appendix A-13 of section
38.41 of
this Part [rule]).
(2) Airborne
radioactivity measurements and DAC values shall not be used as the primary
means to assess the deep dose equivalent when the airborne radioactive material
includes radionuclides other than noble gases or if the cloud of airborne
radioactive material is not relatively uniform. The determination of the deep
dose equivalent to an individual in these cases shall be based upon
measurements using instruments or individual monitoring devices.
(d) Determination of internal
exposure.
(1) For purposes of assessing dose
used to deter mine compliance with occupational dose equivalent limits, the
licensee shall, when required under section
38.24 of
this Part (rule), take any of the following measurements as may be necessary
for timely and appropriate detection and assessment of intake of radioactivity
by individuals:
(i) concentrations of
radioactive materials in air in work areas;
(ii) quantities of radionuclides in the
body;
(iii) quantities of
radionuclides excreted from the body; or
(iv) combinations of these
measurements.
(2) Unless
respiratory protective equipment is used, as provided in section
38.26
of this Part (rule), 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.
(3) 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:
(i) 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
(ii) separately assess
the contribution of fractional intakes of Class D, W, or Y compounds of a given
radionuclide to the committed effective dose equivalent.
(4) If the licensee chooses to assess intakes
of Class Y material using the measurements listed in subparagraph (1)(ii) or
(iii) of this subdivision, the licensee or registrant may delay the recording
and reporting of the assessments for periods up to seven months, unless
otherwise required by section
38.29(b)(1) and
(2) of this Part (rule). This delay permits
the licensee or registrant to make additional measurements basic to the
assessments.
(5) 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:
(i) the sum of the ratios of the
concentration to the appropriate DAC value, that is, D, W, or Y, from Appendix
A-13, for each radionuclide in the mixture; or
(ii) the ratio of the total concentration for
all radionuclides in the mixture to the most restrictive DAC value for any
radionuclide in the mixture.
(6) 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.
(7) When a mixture of radionuclides in air
exists, a licensee may disregard certain radionuclides in the mixture if:
(i) the licensee uses the total activity of
the mixture in demonstrating compliance with the dose limits in subdivision (a)
of this section and in complying with the monitoring requirements in section
38.24(b)
of this Part (rule);
(ii) the
concentration of any radionuclide disregarded is less than 10 percent of its
DAC; and
(iii) the sum of these
percentages for all of the radionuclides disregarded in the mixture does not
exceed 30 percent.
(8)
When determining the committed effective dose equivalent, the following
information may be considered:
(i) 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 0.05 Sv (5 rem) for
radionuclides that have their ALIs or DACs based on the committed effective
dose equivalent;
(ii) for an ALI
and associated DAC which are based upon the nonstochastic organ dose limit of
0.50 Sv (50 rem), the intake of radionuclides that would result in a committed
effective dose equivalent of 0.05 Sv (5 rem), that is, the stochastic ALI, is
listed in parentheses in Appendix A-13. 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 shall also demonstrate that the
limit in clause (a)(1)(i)(b) of this section is met.
(e) Determination of prior
occupational dose.
(1) For each individual who
may enter the licensee's or registrant's restricted area and is likely to
receive, in a year, an occupational dose requiring monitoring pursuant to
section
38.24 of
this Part (rule), the licensee or registrant shall:
(i) determine the occupational radiation dose
received during the current year; and
(ii) request in writing the records of
lifetime cumulative occupational radiation dose.
(2) Prior to permitting an individual to
participate in a planned special exposure, the licensee or registrant shall
determine:
(i) the internal and external
doses received by the individual from all previous planned special exposures;
and
(ii) all doses in excess of the
limits received during the individual's lifetime, including doses received
during accidents and emergencies.
(3) In complying with the requirements of
paragraph (1) of this subdivision, a licensee or registrant may:
(i) accept, as a record of the occupational
dose that the individual received during the current year, a written signed
statement from the individual, or from the individual's most recent employer
for work involving radiation exposure, that discloses the nature and the amount
of any occupational dose that the individual received during the current
year;
(ii) accept, as the record of
lifetime cumulative radiation dose, a completed and up-to- date department form
for cumulative occupational radiation exposure history, or equivalent, signed
by the individual and countersigned by an appropriate official of the most
recent employer for work involving radiation exposure, or the individual' s
current employer, if the individual is not employed by the licensee or
registrant; and
(iii) obtain
reports of the individual's dose equivalent from the most recent employer for
work involving radiation exposure, or the individual's current employer, if the
individual is not employed by the licensee or registrant, by telephone,
telegram, facsimile, or letter. The licensee or registrant shall request a
written verification of the dose data if the authenticity of the transmitted
report cannot be established.
(4) The licensee or registrant shall record
the exposure history, required by paragraph (1) of this subdivision, on the
department form for cumulative occupational radiation exposure history, or
other clear and legible record and shall include all the information required
on that form.
(i) The form or record shall
show each period in which the individual received occupational exposure to
radiation or radioactive material and shall be signed by the individual who
received the exposure. For each period for which the licensee or registrant
obtains reports, the licensee or registrant shall use the dose shown in the
report in preparing the form or record. For any period for which the licensee
or registrant does not obtain a report, the licensee or registrant shall place
a notation on the form or record indicating the periods of time for which data
are not available.
(ii) Licensees
or registrants are not required to reevaluate the separate external dose
equivalents and internal committed dose equivalents, or intakes of
radionuclides, which were assessed under the regulations in effect before the
effective date of these regulations. Occupational exposure histories obtained
and recorded on the department form for cumulative occupational radiation
exposure history before the effective date of these regulations would not have
included effective dose equivalent, but may be used in the absence of specific
information on the intake of radionuclides by the individual.
(5) If the licensee or registrant
is unable to obtain complete records of an individual's current and previously
accumulated occupational dose, the licensee or registrant shall:
(i) when establishing administrative controls
under paragraph (a)(6) of this section for the current year, assume that the
allowable dose limit for the individual is reduced by 12.5 mSv (1.25 rem) for
each quarter for which records were unavailable and the individual was engaged
in activities that could have resulted in occupational radiation exposure;
and
(ii) not authorize the
individual to receive any planned special exposures.
(6) The licensee or registrant shall retain
the records on the department form for cumulative occupational radiation
exposure history or equivalent, until the commissioner terminates each
pertinent license or registration. The licensee or registrant shall retain
records used in preparing this form or equivalent for three years after the
record is made.
(f)
Planned special exposures. A licensee or registrant may authorize an adult
worker to receive doses which are in addition to, and which are accounted for
separately from, the doses received under the limits specified in subdivision
(a) of this section provided that each of the following conditions is
satisfied:
(1) The licensee or registrant
authorizes the planned special exposure only in an exceptional situation when
alternatives that might avoid the higher exposure are unavailable or
impractical.
(2) The licensee or
registrant, and the employer if the employer is not the licensee or registrant,
specifically authorizes the planned special exposure, in writing, before the
exposure occurs.
(3) Before a
planned special exposure, the licensee or registrant ensures that each worker
involved is:
(i) informed of the purpose of
the planned operation;
(ii)
informed of the estimated doses and associated potential risks and specific
radiation levels or other conditions that might be involved in performing the
task; and
(iii) instructed in the
measures to be taken to keep the dose ALARA considering other risks that may be
present.
(4) Prior to
permitting an individual to participate in a planned special exposure, the
licensee or registrant ascertains prior doses as required by paragraph (e)(2)
of this section.
(5) Subject to
paragraph (a)(2) of this section, the licensee or registrant shall not
authorize a planned special exposure that would cause an individual to receive
a dose from all planned special exposures that would exceed:
(i) the numerical values of any of the dose
limits in paragraph (a)(1) of this section in any year; and
(ii) five times the annual dose limits in
paragraph (a)(1) of this section during the individual's lifetime.
(6) The licensee or registrant
maintains records of the conduct of a planned special exposure in accordance
with section
38.28(e)
of this Part and submits a written report in accordance with section
38.29(d).
(7) The licensee or registrant records the
best estimate of the dose resulting from the planned special exposure in the
individual's record and informs the individual, in writing, of the dose within
30 days from the date of the planned special exposure. The dose from planned
special exposures shall not be considered in controlling future occupational
dose of the individual pursuant to paragraph (a)(1) of this section but shall
be included in evaluations required by paragraphs (4) and (5) of this
subdivision.
(g)
Occupational dose limits for minors. The annual occupational dose limits for
minors are 10 percent of the annual occupational dose limits specified for
adult workers in subdivision (a) of this section.
(h) Dose to an embryo/fetus.
(1) The licensee or registrant shall ensure
that the dose to an embryo/fetus during the entire pregnancy, which results
from occupational exposure of a declared pregnant woman, does not exceed 5 mSv
(0.5 rem). (See section
38.28[f]of
this Part for recordkeeping requirements.)
(2) The licensee or registrant shall review
past exposure history and adjust working conditions so as to avoid a monthly
total effective dose equivalent of more than 50 mrem to the embryo/fetus of a
declared pregnant woman.
(3) The
dose to an embryo/fetus shall be taken as the sum of:
(i) the deep dose equivalent to the declared
pregnant woman during the entire pregnancy period; and
(ii) the dose to the embryo/fetus from
radionuclides in the embryo/fetus and radionuclides in the declared pregnant
woman during the entire pregnancy period.
(4) If by the time the woman declares
pregnancy to the licensee or registrant, the dose to the embryo/fetus exceeded
4.5 mSv (0.45 rem), the licensee or registrant shall be deemed to be in
compliance with paragraph (1) of this subdivision if the additional dose to the
embryo/fetus does not exceed 0.50 mSv (0.05 rem) during the remainder of the
pregnancy.