Energy-dispersive X-ray fluorescence analysis of uranium-contaminated stainless-steel surfaces by eliminating the iron sum peak using a titanium filter

During energy-dispersive X-ray fluorescence (EDXRF) measurements of stainless steel, sum peaks originating from iron are frequently observed. Among these, the Fe Kα + Kβ sum peak overlaps with the U Lα peak, complicating the analysis of uranium contamination on stainless-steel surfaces. While secondary X-ray filters can mitigate such sum peaks, integrating them into commercially available portable EDXRF analyzers poses technical challenges. This study presents a straightforward method for eliminating iron sum peak interference. A titanium foil, placed over the uranium-contaminated area on a stainless-steel surface, attenuates incident X-rays while allowing significantly higher transmission of U Lα X-rays than Fe K X-rays. EDXRF measurements were conducted on uranium-contaminated stainless-steel models using a portable EDXRF spectrometer equipped with a titanium foil of optimized thickness as a filter. In the resulting EDXRF spectrum, the intensity of the U Lα peak showed a direct correlation with the uranium content, enabling accurate detection of uranium levels as low as 61 ng. The proposed method achieves a uranium detection sensitivity approximately 100 times greater than conventional α-survey meter methods.