Analysis of nuclear materials by energy dispersive X-ray fluorescence and spectral effects of alpha decay

Energy dispersive X-ray fluorescence (EDXRF) spectra collected from alpha emitters are complicated by artifacts inherent to the alpha decay process, particularly when using portable instruments. For example, ²³⁹Pu EDXRF spectra exhibit a prominent uranium L X-ray emission peak series due to sample alpha decay rather than source-induced X-ray fluorescence. A portable EDXRF instrument was used to collect qualitative spectra from plutonium and americium, and metal alloy identification was performed on a Pu-contaminated steel sample. Significant alpha decay-induced X-ray fluorescence peaks were observed in spectra obtained from the plutonium and americium samples due to the ²³⁵U and ²³⁷Np daughters, respectively. The plutonium sample was also analyzed by wavelength dispersive XRF (WDXRF) to demonstrate that alpha decay-induced X-ray emission has a negligible effect on WDXRF spectra.