Year
1998
Abstract
As part of a recent proposal for decommissioning the K-25 Site at Oak Ridge National Laboratory, studies were conducted using the Variable Box Waste Assay System (VBWAS), a nondestructive assay instrument built by BNFL Instruments Inc. Recycling metal from the Oak Ridge site may be possible if 235U contamination levels are at, or below, free release criteria. Established levels for free release are 5000 dpm/100 cm2 for surface alpha activity. No DOE criterion presently exist for free release disposal based on volumetric evaluation. However, surface level contamination of the Oak Ridge metals converted to volumetric counterparts yield free release levels of 1.68 Bq/g (235U Bq per gram of metal) for the motor and 6.4Bq/g for the scrap metal. By comparison, the Minimum Detection Limit (3s) for the VBWAS system for pure 235U was measured at 0.018 Bq/g for the motor and 0.007 Bq/g for scrap metal. The corresponding Minimum Detection Limits for uranium containing 3% 235U were 0.20 Bq/g and 0.08 Bq/g for the motor and scrap metal measurements, respectively. A factor of 2 or greater cost saving could be realized if the retrieved metal can be free released. This report provides descriptions of the motor and scrap metal measurements using the VBWAS and summarizes results of other waste matrices containing uranium at free release levels. Details of the cost saving calculations are presented in this report.