CHARACTERIZATION OF CONSISTENT NDA STANDARDS

By combining calorimetry and traditional analytical methods five sets of unique NDA standards were characterized for the Savannah River Plant (SRP) of E. I. duPont deNemours, Inc. The calorimetry measurements made it possible to nondestructively verify the homogeneity of the plutonia stock and to assure that the analytical aliquots were representative of the parent material. Two assay values were determined by calorimetric assay. When the isotopic composition was determined by mass spectroscopy and alpha pulse height analysis, the agreement between Pu content by calorimetry and controlled potential coulometry was within 0.06% for all five isotopic compositions. When nondestructive, gamma-ray isotopic techniques were used to assay the 1500 gram standards the agreement was within 0.1% for all five materials. The new half-lives and specific power recommended in the latest revision of ANSI N15.22-1987, Calibration Techniques for the Calorimetric Assay of Plutonium Bearing Solids were used for all computations. The standards were certified for plutonium content, isotopic composition, and thermal power. The mass of the standards varied from 20 to 1500 grams with 240 Pu compositions ranging from 3 to 15 percent.