Quartz-Crystal Spectrometer for the Analysis of Plutonium K X-Rays

The ability to quickly quantify the Pu content within spent nuclear fuel (SNF) is essential to nuclear forensics. Analysis of the Pu to U ratio can provide information on fuel which could contribute to the attribution of a fuel sample. 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 count time. 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. This provides a high signal with limited background by decreasing the possible Compton interaction in the detector. The crystal design and the experimental geometry that would allow for the study of high energy x-rays required further attention. In addition, a preliminary MCNP simulation of the energy-direction coupled photon source from the quartz crystal was used to calculate the improved signal-to-noise ratio of the Pu x-ray peak above background.