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|See 105 CMR 120.267.|
(E) In addition to the annual dose limits, the licensee shall limit the soluble uranium intake by an individual to ten milligrams in a week in consideration of chemical toxicity. See footnote 3 of 105 CMR 120.296: Appendix B.
(F) 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 during the current year. See 105 CMR 120.265(E).
120.212: Compliance with Requirements for Summation of External and Internal Doses
(A) If the licensee is required to monitor pursuant to both 105 CMR 120.226(A) and (B), the licensee 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 105 CMR 120.226(A) or only pursuant to 105 CMR 120.226(B), 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 pursuant to 105 CMR 120.212(B), (C) and (D). 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 (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, wT, and the committed dose equivalent, HT,50, per unit intake is greater than 10% of the maximum weighted value of HT,50, that is, wTHT,50, per unit intake for any organ or tissue.
(C) Intake by Oral Ingestion. If the occupationally exposed individual 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.
120.213: Determination of External Dose from Airborne Radioactive Material
(A) Licensees shall, when determining the dose from airborne radioactive material, include the contribution to the deep dose equivalent, lens dose equivalent, and shallow dose equivalent from external exposure to the radioactive cloud. See 105 CMR 120.296: Appendix B, footnotes 1 and 2.
(B) 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 shall be based upon measurements using instruments or individual monitoring devices.
120.214: Determination of Internal Exposure
(A) For purposes of assessing dose used to determine compliance with occupational dose equivalent limits, the licensee shall, when required pursuant to 105 CMR 120.226, 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 105 CMR 120.233, or the assessment of intake is based on bioassays, the licensee 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 may:
(1) use that information to calculate the committed effective dose equivalent, and, if used, the licensee shall document that information in the individual's record;
(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. See 105 CMR 120.296: Appendix B.
(D) If the licensee chooses to assess intakes of Class Y material using the measurements given in 105 CMR 120.214(A)(2) or (3), the licensee may delay the recording and reporting of the assessments for periods up to seven months, unless otherwise required by 105 CMR 120.282 or 105 CMR 120.283. This delay permits the licensee 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 105 CMR 120.296: 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 may disregard certain radionuclides in the mixture if:
(1) the licensee uses the total activity of the mixture in demonstrating compliance with the dose limits in 105 CMR 120.211 and in complying with the monitoring requirements in 105 CMR 120.226(B);
(2) the concentration of any radionuclide disregarded is less than 10% of its DAC; and,
(3) the sum of these percentages for all of the radionuclides disregarded in the mixture does not exceed 30%.
(H) When determining the committed effective dose equivalent, the following information may be considered:
(1) In order to calculate the committed effective dose equivalent, the licensee 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 sievert (5 rems) for radionuclides that have their ALIs or DACs based on the committed effective dose equivalent.
(2) For an ALI and the associated DAC determined by the nonstochastic organ dose limit of 0.5 sievert (50 rems), the intake of radionuclides that would result in a committed effective dose equivalent of 0.05 sievert (5 rems), that is, the stochastic ALI, is listed in parentheses in 105 CMR 120.296: Appendix B, Table I. The licensee may, as a simplifying assumption, use the stochastic ALI to determine committed effective dose equivalent. However, if the licensee uses the stochastic ALI, the licensee shall also demonstrate that the limit in 105 CMR 120.211(A)(1)(b) is met.
120.216: Planned Special Exposures
A licensee or registrant may authorize an adult worker to receive doses in addition to and accounted for separately from the doses received under the limits specified in 105 CMR 120.211 provided that each of the following conditions is satisfied:
(A) The licensee or registrant authorizes a planned special exposure only in an exceptional situation when alternatives that might avoid the dose estimated to result from the planned special exposure are unavailable or impractical.
(B) The licensee or registrant, and employer if the employer is not the licensee or registrant, specifically authorizes the planned special exposure, in writing, before the exposure occurs.
(C) Before a planned special exposure, the licensee or registrant ensures that each individual involved is:
(1) informed of the purpose of the planned operation;
(2) 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
(3) instructed in the measures to be taken to keep the dose ALARA considering other risks that may be present.
(D) Prior to permitting an individual to participate in a planned special exposure, the licensee or registrant ascertains prior doses as required by 105 CMR 120.265(B) during the lifetime of the individual for each individual involved.
(E) Subject to 105 CMR 120.211(B), 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 and all doses in excess of the limits to exceed:
(1) the numerical values of any of the dose limits in 105 CMR 120.211(A) in any year; and
(2) five times the annual dose limits in 105 CMR 120.211(A) during the individual's lifetime.
(F) The licensee or registrant maintains records of the conduct of a planned special exposure in accordance with 105 CMR 120.266 and submits a written report to the Agency in accordance with 105 CMR 120.284.
(G) 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 105 CMR 120.211(A) but shall be included in evaluations required by 105 CMR 120.216(D) and (E).
120.217: Occupational Dose Limits for Minors
The annual occupational dose limits for minors are 10% of the annual occupational dose limits specified for adult workers in 105 CMR 120.211.
120.218: Dose Equivalent to an Embryo/Fetus
(A) The licensee or registrant shall ensure that the dose equivalent to an embryo/fetus during the entire pregnancy, due to occupational exposure of a declared pregnant woman, does not exceed five millisieverts (0.5 rems). See 105 CMR 120.267 for recordkeeping requirements.
(B) The licensee or registrant shall make efforts to avoid substantial variation above a uniform monthly exposure rate to a declared pregnant woman so as to satisfy the limit in 105 CMR 120.218(A).
(C) The dose equivalent to the embryo/fetus is the sum of:
(1) the deep dose equivalent to the declared pregnant woman; and
(2) the dose equivalent resulting from radionuclides in the embryo/fetus and radionuclides in the declared pregnant woman.
(D) If the dose equivalent to the embryo/fetus is found to have exceeded 5.0 mSv (0.5 rem), or is within 0.5 mSv (0.05 rem) of this dose, by the time the woman declares the pregnancy to the licensee or registrant, the licensee or registrant shall be deemed to be in compliance with 105 CMR 120.218(A), if the additional dose to the embryo/fetus does not exceed 0.5 millisievert (0.05 rem) during the remainder of the pregnancy.
RADIATION DOSE LIMITS
120.221: Dose Limits for Individual Members of the Public
(A) Each licensee or registrant shall conduct operations so that:
(1) the total effective dose equivalent to individual members of the public from the licensed or registered operation does not exceed one millisievert (0.1 rem) in a year, exclusive of the dose contribution from background radiation, from any medical administration the individual has received, from exposure to individuals administered radioactive material and released in accordance with 105 CMR 120.540, from voluntary participation in medical research programs, and from the licensee's disposal of radioactive material into sanitary sewerage in accordance with 105 CMR 120.253; and
(2) the dose in any unrestricted area from external sources exclusive of the dose contributions from patients administered radioactive material and released in accordance with 105 CMR 120.540, does not exceed 0.02 millisievert (0.002 rem) in any one hour; and
(3) the total effective dose equivalent to individual members of the public from infrequent exposure to radiation from radiation machines does not exceed 5mSv (0.5 rem).
(B) If the licensee or registrant permits members of the public to have access to restricted areas, the limits for members of the public continue to apply to those individuals.
(C) A licensee, registrant, or an applicant for a license or registration may apply for prior Agency authorization to operate up to an annual dose limit for an individual member of the public of five millisieverts (0.5 rem). This application shall include the following information:
(1) demonstration of the need for and the expected duration of operations in excess of the limit in 105 CMR 120.221(A);
(2) the licensee's or registrant's program to assess and control dose within the five millisieverts (0.5 rem) annual limit; and
(3) the procedures to be followed to maintain the dose ALARA.
(D) In addition to the requirements of 105 CMR 120.200, a licensee subject to the provisions of the U.S. Environmental Protection Agency's generally applicable environmental radiation standards in 40 CFR 190 shall comply with those requirements.
(E) The Agency may impose additional restrictions on radiation levels in unrestricted areas and on the total quantity of radionuclides that a licensee may release in effluents in order to restrict the collective dose.
120.222: Compliance with Dose Limits for Individual Members of the Public
(A) The licensee or registrant shall make or cause to be made surveys of radiation levels in unrestricted areas and radioactive materials in effluents released to unrestricted areas to demonstrate compliance with the dose limits for individual members of the public in 105 CMR 120.221.
(B) A licensee or registrant shall show compliance with the annual dose limit in 105 CMR 120.221 by:
(1) demonstrating by measurement or calculation that the total effective dose equivalent to the individual likely to receive the highest dose from the licensed or registered operation does not exceed the annual dose limit; or,
(2) demonstrating that:
(a) the annual average concentrations of radioactive material released in gaseous and liquid effluents at the boundary of the unrestricted area do not exceed the values specified in 105 CMR 120.296:
Врач общей практики, Equipo cesca, Madrid (Spain). Visiting Professor, International Health, National School of Health, Madrid. Honorary...