Alpha spectrometric evaluation of SRM-995 as a potential uranium/thorium double tracer system for age-dating uranium materials

作者：Stanley F E^*; Glover S E; Stalcup A M; Spitz H B; Beals Donna

来源：Journal of Radioanalytical and Nuclear Chemistry, 2013, 296(2): 1085-1090.

DOI：10.1007/s10967-012-2094-2

• Age-dating
• Alpha spectrometry
• Nuclear forensics
• Uranium
• SRM-995
• Thorium

Uranium-233 (t(1/2) similar to 1.59E5 years) is an artificial, fissile isotope of uranium that has significant importance in nuclear forensics. The isotope provides a unique signature in determining the origin and provenance of uranium-bearing materials and is valuable as a mass spectrometric tracer. Alpha spectrometry was employed in the critical evaluation of a U-233 standard reference material (SRM-995) as a dual tracer system based on the in-growth of Th-229 (t(1/2) similar to 7.34E3 years) for similar to 35 years following radiochemical purification. Preliminary investigations focused on the isotopic analysis of standards and unmodified fractions of SRM-995; all samples were separated and purified using a multi-column anion-exchange scheme. The Th-229/U-233 atom ratio for SRM-995 was found to be 1.598E-4 (+/-4.50 %) using recovery-corrected radiochemical methods. Using the Bateman equations and relevant half-lives, this ratio reflects a material that was purified similar to 36.8 years prior to this analysis. The calculated age is discussed in contrast with both the date of certification and the recorded date of last purification.

• 出版日期2013-5