Level III baseline risk evaluation for Building 3505 at Oak Ridge National Laboratory, Oak Ridge, Tennessee

摘要

The Level III Baseline Risk Evaluation (BRE) for Building 3505, the ORNL Metal Recovery Facility, provides an analysis of the potential for adverse health effects, current or future, associated with the presence of hazardous substances in the building. The Metal Recovery Facility was used from 1952 through 1960 to process large quantities of radioactive material using the PUREX process for the recovery of uranium-238, plutonium-239, neptunium-237, and americium-241. The facility consists of seven process cells (A through G), a canal, a dissolver room, a dissolver pit, an office, locker room, storage area, control room, electrical gallery, shop, and makeup area. The cells were used to house the nuclear fuel reprocessing equipment, and the canal was constructed to be used as a water-shielded transfer canal. Currently, there are no known releases of radioactive contaminants from Building 3505. To perform the BRE, historical radiological survey data were used to estimate the concentration of alpha- and beta/gamma emitting radionuclides in the various cells, rooms, and other areas in Building 3505. Data from smear surveys were used to estimate the amount of transferable contamination (to which receptors can be exposed via inhalation and ingestion), and data from probe surveys were used to estimate the amount of both fixed and transferable contamination (from which receptors can receive external exposure). Two land use scenarios, current and future, and their subsequent exposure scenarios were explored in the BRE. Under the current land use scenario, two exposure scenarios were evaluated. The first was a worst-case industrial exposure scenario in which the receptor is a maintenance worker who works 8 hours/day, 350 days/year in the building for 25 years. In the second, more realistic exposure scenario, the receptor is a surveillance and maintenance (S&M) worker who spends two 8-hour days/year in the building for 25 years.