Net concentration means the difference between the concentration of a given substance in a sample taken of the discharge and the concentration of the same substances in a sample taken at the intake which supplies water to the given process. For the purpose of this definition, samples that are taken to determine the net concentration shall always be 24-hour composite samples made up of at least six increments taken at regular intervals throughout the plant day.
Derived air concentration (DAC) means the concentration of a given radionuclide in air which, if breathed by the reference man for a working year of 2,000 hours under conditions of light work, results in an intake of one ALI. For purposes of these regulations, the condition of light work is an inhalation rate of 1.2 cubic meters of air per hour for 2,000 hours in a year. DAC values are given in Table I, Column 3, of Appendix B.
U.S.-flag air carrier means an air carrier holding a certificate under 49 U.S.C. Chapter 411.
Foreign flag vessel means any vessel that is not a U.S.-flag vessel.
Tier 2 Wire Centers are those Embarq Wire Centers that are not Tier 1 Wire Centers but contain at least three (3) Fiber-based Collocators, at least 24,000 Business Lines, or both. Once a Wire Center is determined to be a Tier 2 Wire Center, that Wire Center is not subject to later reclassification as a Tier 3 Wire Center.