Applications of In-Situ Solution NDA at Y-12 National Security Complex

An extension to the Generalized Geometry Holdup (GGH) assay method was developed by Los Alamos National Laboratory that enabled the Y-12 National Security Complex to measure highly enriched uranium solutions in storage tanks. Utilizing this method allowed Y-12 to complete a physical inventory in the chemical recovery area in November 2000. This was the first physical inventory for the area in over six years, and was accomplished over two years earlier than would have been possible without utilizing the solution NDA measurements. Pending complete restart of operations in the chemical recovery area, Y-12 continues to utilize the LANL developed method for measuring solutions stored in active and static tank systems. Routine re-measurement and limited comparison to destructive analysis data have been ongoing for over two years and confidence in the measurement method has matured. The measurement method has been adapted for other monitoring purposes to verify accountability values with field measurements. However, various limitations have required novel approaches for determining such things as tank fill height, volumes, and attenuation correction factors. The measurements, assumptions, calculations, and comparison to other analyses will be discussed.