[en] The US Department of Energy (DOE), in DOE Order 5400.5 (1990), directs operators of DOE facilities to apply the Best Available Technology (BAT) to control radiological liquid effluents from these facilities when specific conditions are present. DOE has published interim guidance to assist facility operators in knowing when a BAT analysis is needed and how such an analysis should be performed and documented. The purpose of the guidance is to provide a uniform basis in determining BAT throughout DOE and to assist in evaluating BAT determinations during programmatic audits. The BAT analysis process involves characterizing the effluent source; identifying and selecting candidate control technologies; evaluating the potential environmental, operational, resource, and economic impacts of the control technologies; developing an evaluation matrix for comparing the technologies; selecting the BAT; and documenting the evaluation process. The BAT analysis process provides a basis for consistent evaluation of liquid effluent releases, yet allows an individual site or facility the flexibility to address site-specific issues or concerns in the most appropriate manner