Browsing by Author "Wallenius, M"

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    Application of lead and strontium isotope ratio measurements for the origin assessment of uranium ore concentrates
    (American Chemical Society, 2009-10-15) Varga, Z; Wallenius, M; Mayer, K; Keegan, EA; Millett, S
    Lead and strontium isotope ratios were used for the origin assessment of uranium ore concentrates (yellow cakes) for nuclear forensic purposes. A simple and low-background sample preparation method was developed for the simultaneous separation of the analytes followed by the measurement of the isotope ratios by multicollector inductively coupled plasma mass spectrometry (MC-ICPMS). The lead isotopic composition of the ore concentrates suggests applicability for the verification of the source of the nuclear material and by the use of the radiogenic 207Pb/206Pb ratio the age of the raw ore material can be calculated. However, during data interpretation, the relatively high variation of the lead isotopic composition within the mine site and the generally high contribution of natural lead as technological contamination have to be carefully taken into account. The 87Sr/86Sr isotope ratio is less prone to the variation within one mine site and less affected by the production process, thus it was found to be a more purposeful indicator for the origin assessment and source verification than the lead. The lead and strontium isotope ratios measured and the methodology developed provide information on the initial raw uranium ore used, and thus they can be used for source attribution of the uranium ore concentrates. © 2009, American Chemical Society
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    The application of radiochronometry during the 4th collaborative materials exercise of the nuclear forensics international technical working group (ITWG)
    (Springer Nature, 2018-02-06) Kristo, MJ; Williams, R; Gaffney, AM; Kayzar-Boggs, TM; Schorzman, KC; Lagerkvist, P; Vesterlund, A; Ramebäck, H; Nelwamondo, AN; Kotze, D; Song, K; Lim, SH; Han, SH; Lee, CG; Okubo, A; Maloubier, D; Cardona, D; Samuleev, P; Dimayuga, I; Varga, Z; Wallenius, M; Mayer, K; Loi, E; Keegan, EA; Harrison, JJ; Thiruvoth, S; Stanley, FE; Spencer, KJ; Tandon, L
    In a recent international exercise, 10 international nuclear forensics laboratories successfully performed radiochronometry on three low enriched uranium oxide samples, providing 12 analytical results using three different parent-daughter pairs serving as independent chronometers. The vast majority of the results were consistent with one another and consistent with the known processing history of the materials. In general, for these particular samples, mass spectrometry gave more accurate and more precise analytical results than decay counting measurements. In addition, the concordance of the 235U–231Pa and 234U–230Th chronometers confirmed the validity of the age dating assumptions, increasing confidence in the resulting conclusions. © 2018 U.S. Government