Experience Gained and New Correction Techniques Developed based on the Mixed Waste Focus Area NDA System Capability Evaluation Project

Canberra Industries participated in the EM30 sponsored Mixed Waste Focus Area (MWFA) NDA System Capability Evaluation Project in late 1997 and early 1998, providing three NDA trailers for evaluation: Segmented Gamma Scanner (SGS) with isotopics capability, High Efficiency Passive Neutron Counter (HENC), and a multiple germanium detector Gamma NDA and Isotopics System (IQ3). The project evaluated the performance of these three systems as well as NDA systems provided by other commercial vendors and DOE funded facilities. The tests included 11 surrogate drums and 21 real waste drums generated at RFETS and stored at INEEL. These drums represented the range of matrices and gram loadings that INEEL will be required to assay to characterize their waste for WIPP certification. The demonstration project provided an opportunity to assay several difficult matrices and source configurations that challenged the capabilities of each of the NDA systems. The data from this project have provided valuable experience, which is not routinely available to a commercial vendor, in the measurement problems associated with assaying matrices such as sludges and MSE salts, as well as unexpected source configurations and isotopic ratios. This paper covers a discussion on experience gained, validating both the successes and limitations of each of these systems as well as defining the need for test data to evaluate new assay correction and data integration techniques to improve the overall precision and accuracy of the assay results. The results obtained with these instruments demonstrates the need for the integration of results from both the passive neutron and quantitative gamma/isotopics system in order to achieve the best possible characterization data over the range of conditions encountered.