declared pregnant worker: A woman who has voluntarily declared to her employer, in writing, her pregnancy for the
purpose of being subject to the occupational exposure limits to the embryo/fetus as provided in Article 215. This
declaration may be revoked, in writing, at any time by the declared pregnant worker [see 835.2(a)] .
decontamination: Process of removing radioactive contamination from personnel, equipment, or areas.
derived air concentration (DAC): For the radionuclides listed in Appendix A of 10 CFR 835, the airborne
concentration that equals the ALI divided by the volume of air breathed by an average worker for a working year of 2000
hours (assuming a breathing volume of 2400m3). For radionuclides listed in Appendix C of 10 CFR 835, the air
immersion DACs were calculated for a continuous, non-shielded exposure via immersion in a semi-infinite atmospheric
cloud. The values are based upon the derived airborne concentration found in Table 1 of the U. S. Environmental
Protection Agency's Federal Guidance Report No. 11, Limiting Values of Radionuclide Intake and Air Concentration and
Dose Conversion Factors for Inhalation, Submersion, and Ingestion, published September 1988 [see 835.2(a)].
derived air concentration-hour (DAC-hour): The product of the concentration of radioactive material in air
(expressed as a fraction or multiple of the DAC for each radionuclide) and the time of exposure to that radionuclide, in
hours [see 835.2(a)].
disintegration per minute (dpm): The rate of emission by radioactive material as determined by correcting the counts
per minute observed by an appropriate detector for background, efficiency, and geometric factors associated with the
DOE activity: An activity taken for or by the DOE in a DOE operation of facility that has the potential to result in the
occupational exposure of an individual to radiation or radioactive material. The activity may be, but is not limited to,
design, construction, operation, decontamination or decommissioning. To the extent appropriate, the activity may
involve a single DOE facility or operation or a combination of facilities and operations, possibly including an entire site
or multiple DOE sites [see 835.2(a)].
DOELAP: Department of Energy Laboratory Accreditation Program for personnel dosimetry and bioassay programs.
dose: A general term for absorbed dose, dose equivalent, effective dose equivalent, committed dose equivalent,
committed effective dose equivalent, or total effective dose equivalent [see 835.2(b)]. Various technical terms, such as
dose equivalent, effective dose equivalent, and collective dose, are used to describe the amount of radiation an exposed
individual receives. These terms are used to describe the differing interactions of radiation with tissue as well as to assist
in the management of personnel exposure to radiation.
Some types of radiation, such as neutron and alpha, deposit their energy more densely in affected tissue than
gamma radiation, thereby causing more damage to tissue. The term dose equivalent, measured in units of
rem, is used to take into account this difference in tissue damage. Therefore 1 rem from gamma radiation
causes damage equivalent to 1 rem from alpha radiation. However, it takes one-twentieth as much energy
from alpha radiation, as compared with gamma radiation, to produce this 1 rem dose equivalent.