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On 25 June 2018, the U.S. Environmental Protection Agency's (EPA) Office of Radiation and Indoor Air published Federal Guidance Report (FGR) No. 15, External Exposure to Radionuclides in Air, Water, and Soil. FGR 15 tabulates age-specific reference person effective dose-rate coefficients for 1,252 radionuclides based on external exposure to radionuclides distributed in air, water, and soil. The report updates and expands the 1993 FGR 12. Compared to FGR 12, FGR 15 incorporates:

• Six different age groups (FGR 12 had one).
• Updated tissue weighting factors (as recommended in International Commission on Radiological Protection [ICRP] Publication 103).
• Updated radionuclide decay data (as provided in ICRP Publication 107).
• Improved computing power to provide more precise calculations.

FGR 12 is not being rescinded because it will still be required when regulations specify use of external dose coefficients from either ICRP Publication 26 or 30.

FGR 15 was developed in close collaboration with scientists at Oak Ridge National Laboratory's (ORNL) Center for Radiation Protection Knowledge. The full report is available on the EPA website. Additionally, tissue-specific equivalent dose rate coefficients (not included in the report) were tabulated and are available online from ORNL.

As noted, this technical report provides external dose-rate coefficients based on dosimetric weighting factors in ICRP Publication 103 and radionuclide decay data from ICRP Publication 107. However, FGR 12 is still the appropriate guidance to use when regulations specify use of ICRP Publication 26-based methodology.

If you have questions about this FGR 15, please contact Mike Boyd.