Document: 10 CFR Part 20
Document ID: f5e61647-ea86-4e01-9cdd-47437f477e62
Document Type: cfr
Title: Determination of internal exposure.
Source: 10 CFR Part 20
Source URL: https://www.ecfr.gov/current/title-10/part-20/section-20.1204
Revision Date: 
Chapter: 
Section ID: 20.1204
CFR Part: 20
CFR Title: 10

Content:
§ 20.1204 Determination of internal exposure. ( a ) For purposes of assessing dose used to determine compliance with occupational dose equivalent limits, the licensee shall, when required under § 20.1502 , 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 § 20.1703 , 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 or 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; and ( 2 ) Upon prior approval of the Commission, adjust the DAC or ALI values to reflect the actual physical and chemical characteristics of airborne radioactive material (e.g., 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 (see appendix B to part 20) to the committed effective dose equivalent. ( d ) If the licensee chooses to assess intakes of Class Y material using the measurements given in § 20.1204(a)(2) or (3) , the licensee may delay the recording and reporting of the assessments for periods up to 7 months, unless otherwise required by §§ 20.2202 or 20.2203 , in order to permit 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