Evaluation of Exposure to Technologically Enhanced Naturally Occurring Radioactive Materials (TENORM) in the Phosphate Industry
The overall objective of this investigation was to provide information to the state of Florida regarding the radiation exposures to workers in the phosphate industry due to technologically enhanced naturally occurring radioactive materials (TENORM) and to provide recommended methods for reducing those exposures. This objective was met by collecting existing radiological data specific to Florida and the phosphate industry, and generating new data from sampling activities. The sampling effort involved phosphate mines, chemical plants, and outside contractors. External exposures were monitored using scintillation (micro-R) meters, ion chambers, lithium fluoride thermoluminescent dosimeters, and aluminum oxide dosimeters in conjunction with time and motion studies. Internal routes of exposure (mainly inhalation) were studied using air sampling, gross alpha and beta counting, and deposition sample analysis. The mean annual total effective dose equivalent (TEDE) to a phosphate industry worker was computed using Latin Hypercube sampling on measured parameters for each of five generalized areas. The areas and results (TEDE average, 99th percentile) in mrem, and rounded to the nearest whole number, are: mining area (12,20), rock handling area (30, 60), phosphoric acid production area (34, 45), dry products (granular) area (38, 55), shipping area (112, 350), and contracted service worker (8, 11).