Abstract
In the 50 years that the Oak Ridge National Laboratory has been conducting energy research, many operations involved the use of hot perchloric acid in laboratory hoods. In the past, some of these operations were conducted in hoods not designed for use with the hot acid. Salts resulting from these operations or from subsequent corrosion, if accumulated in these systems, can possibly lead to flammable and explosive conditions. In 1991, the Laboratory initiated a study to determine whether these hoods and exhaust systems were contaminated with perchlorate salts. A Perchloric Acid Committee was established consisting of industrial hygienists, chemists, engineers, and health physicists, as well as personnel from industrial safety, fire protection, and environmental compliance. The study identified hoods and systems currently and historically used for hot perchloric acid procedures by a questionnaire survey. Evaluation procedures were established and sampling of suspect and confirmed hoods was undertaken. An analysis of the initial sampling results provided a workable decision process to determine what constituted a health and safety risk. The committee concluded that systems in which aqueous samples equaled or exceeded 750 mg/L, or 70 mg/M2 on wiped surface samples, should be considered contaminated. These systems were restricted in use and were scheduled for decontamination. Decontamination procedures were established. A pilot project in which three systems were dismantled, cleaned, and replaced without incident, accident, or environmental contamination proved the procedures adequate and appropriate.