Use of DAC-Hours for Radiation Work Permit Suspension Guides and Validation of Respiratory Equipment Selection at the Savannah River Site


D. J. Hadlock, S. A. Epperson


Historically, the Savannah River Site, like many Department of Energy sites, has used some multiple of the expected Derived Air Concentration (DAC) of a radionuclide as a suspension guide for Radiological Work Permits (RWP) or validation of selected respiratory protection equipment. The term DAC expresses the concentration of a radionuclide in air, typically in microcuries per cubic centimeter. Even though the term DAC is derived from an intake of radioactivity (annual limit on intake) that would result in a defined estimated dose to a worker, knowing only the DAC value does not allow a worker's potential dose to be determined. Recently, the Savannah River Site has converted to the use of DAC-hours (DAC-hr) for RWP suspension guides and respiratory equipment validation. The term DAC-hr takes into account not only the concentration of the radionuclide in air (DAC) but also the time the individual was exposed, allowing an estimate of a worker's dose to be determined. The conversion to DAC-hr resulted in four benefits to the radiation protection program without increasing the risk to workers: (1) consistency with the constant air monitor (CAM) alarm setpoint protocol; (2) consistency with internal dosimetry terminology; (3) an a priori determination of the potential risk to a worker; and (4) reduced complexity/error in field calculations. This paper outlines the justification for the conversion to DAC-hr, the protocols used for field and count room calculations, and the implementation process utilized at the Savannah River Site.


This abstract was presented at the 37th Annual Midyear Meeting, "Air Monitoring and Internal Dosimetry", Air Monitoring Users Group Special Session, Part 1, 2/8/2004 - 2/11/2004, held in Augusta, GA.

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