40 CFR § 61.21 - Definitions.
As used in this subpart, all terms not defined here have the meaning given them in the Clean Air Act or subpart A of part 61. The following terms shall have the following specific meanings:
(a) Active mine means an underground uranium mine which is being ventilated to allow workers to enter the mine for any purpose.
(b) Effective dose equivalent means the sum of the products of the absorbed dose and appropriate effectiveness factors. These factors account for differences in biological effectiveness due to the quality of radiation and its distribution in the body of reference man. The unit of the effective dose equivalent is the rem. The method for calculating effective dose equivalent and the definition of reference man are outlined in the International Commission on Radiological Protection's Publication No. 26.
(c) Underground uranium mine means a man-made underground excavation made for the purpose of removing material containing uranium for the principal purpose of recovering uranium.