THE CHEMICAL HAZARDS ASSESSMENT PRIOR TO DD OF THE PLUTONIUM FINISHING PLANT, HANFORD NUCLEAR RESERVATION

摘要

This report describes the evaluation methods and results of a chemical safety status assessment of the process equipment at the U.S. Department of Energy Hanford Nuclear Reservation Plutonium Finishing Plant. This assessment, designated as the Plutonium Finishing Plant Residual Chemical Hazards Assessment, focused particular emphasis on the idle and inactive plant systems, though certain active areas also were examined to the extent that these were examined during a previous facility vulnerability assessment completed in 1999. The Plutonium Finishing Plant is located in the 200 West Area of the Hanford Nuclear Reservation that is situated in south central Washington State. The Plutonium Finishing Plant, consisting of several large and small buildings, is a former processing complex. Currently, the Plutonium Finishing Plant activities are focused on the stabilization and packaging of plutoniumbearing materials left from plutonium weapons material processing. Decontamination and decommissioning planning recently has been completed and the Plutonium Finishing Plant is slated for decommissioning to slab-ongrade. The assessment effort was initiated to ensure personnel safety, to facilitate safe decommissioning activities, and to satisfy a Hanford Federal Facility Agreement and Consent Order Interim Milestone M-83-21. The Hanford Federal Facility Agreement and Consent Order, signed by the U. S. Environmental Protection Agency, the Washington State Department of Ecology, and the U.S. Department of Energy, is a comprehensive cleanup and compliance agreement for achieving compliance with the Comprehensive Environmental Response Compensation and Liability Act of 1980 remedial action provisions and with the Resource Conservation and Recovery Act of 1976 treatment, storage, and disposal unit regulations and corrective action provisions. The residual chemical hazards assessment focused on evaluating risk associated with Plutonium Finishing Plant process equipment, including tanks, piping, and waste lines that could contain residual chemicals. Relative risk scoring was performed using much the same method as was employed during the previous facility vulnerability assessment. Considerations were given to the potential severity of hazards such as the potential of physical injury to humans, potential exposure to humans, and significance of secondary impact. Another important factor considered was the likelihood of occurrence. The likelihood of occurrence depends on design, operation, containment vessel condition, emergency planning and safety basis, and maintenance and inspection. A mathematical expression was developed to quantify relative risk. The relative risk score was expressed as a numerical product of the two quantities representing the severity and the likelihood of occurrence. No item was found to have a significant risk that required response actions prior to final deactivation. No relative risk score exceeded 15 out of a possible 100 (scores obtained during the previous facility vulnerability assessment reached 56). The final disposition of all residual chemicals residing in inactive process equipment will occur with the decommissioning of the Plutonium Finishing Plant complex.