W. Charlton, A. Goodsell, “Bent-Crystal Spectrometer Analyzing Plutonium K X-Rays for Applications in Nuclear Forensics”, Proceedings of the INMM 52nd Annual Meeting, Palm Desert, CA, July 17-21, 2011.
The ability to quickly quantify the Pu content within used nuclear fuel is essential to nuclear forensics. Analysis of the Pu to U ratio can provide information on fuel and reactor history, including age, burnup and reactor type. Plutonium concentration data can be acquired through non-destructive analysis (NDA) by detecting self-induced x-ray fluorescence (XRF) from Pu in the fuel. However, during conventional spectroscopy, the characteristic Pu x-ray peak of interest lies beneath background and requires an extended exposure time. Bent-crystal spectrometers allow x-rays of selected energies, obeying Bragg’s law for coherent scattering of incident photons, to be focused directly onto a detector, thus providing a high signal with limited background by decreasing the possible Compton interaction in the detector. Determining a useable crystal and experimental geometry that allows for the study of high energy x-rays requires additional attention. While previous experiments investigating wavelength dispersive bent-crystals have been performed, they were primarily concerned with lower x-ray energies (< 60 keV). The fluorescent x-rays of interest are from the plutonium K-series, ranging from 99.55 to 120.70 keV.