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Book Description
Energy-dispersive x-ray fluorescence analysis (XRFA) can be used to measure nondestructively pure and mixed U/Pu concentrations in process streams and hold tank solutions. The 122-keV gamma ray from 57Co excites the actinide K x rays which are detected by a HPGe detector. A computer- and disk-based analyzer system provides capability for making on-stream analyses, and the noninvasive measurement is easily adapted directly to appropriate sized pipes used in a chemical reprocessing plant. Measurement times depend on concentration and purpose but vary from 100 to 500s for process control of strong to weak solutions. Accountability measurements require better accuracy thus more time; and for solutions containing plutonium, require a measurement of the solution radioactivity made with an automatic shutter that eclipses the two exciting sources. Plutonium isotopic abundances can also be obtained. Concentrations in single or dual element solutions from less than 1 g/l to over 200 g/l are determined to an accuracy of 0.2% after calibration of the system. For mixed solutions the unknown ratio of U to Pu is linearly related to the net U/Pu K x-ray intensities. Concentration values for ratios different than the calibration ratio require only small corrections to the values derived from a calibration polynomial. Minor fission product contamination does not prevent concentration determinations by XRFA. The computer-based system also allows real-time dynamic concentration measurements to be made.