Certification of uranium isotope amount ratios in a suite of uranium ore concentrate certified reference materials

Zhang, R.*; Nadeau, K.*; Gautier, E. A.*; Babay, P. A.*; Ramella, J.*; Virgolici, M.*; Serban, A. E.*; Fugaru, V.*; Kimura, Yoshiki  ; Venchiarutti, C.*; Richter, S.*; Aregbe, Y.*; Varga, Z.*; Wallenius, M.*; Mayer, K.*; Seo, H.*; Choi, J. Y.*; Tobi, C.*; Fayek, M.*; Sharpe, R.*; Samperton, K. M.*; Genetti, V. D.*; Lindvall, R. E.*; Inglis, J. D.*; Denton, J. S.*; Reinhard, A. A.*; Francisco, B.*; Zhao, X.*; Kieser, L.*; He, J.*; Gao, Y.*; Meija, J.*; El-Jaby, A.*; Yang, L.*; Mester, Z.*

In this study, data from thirteen laboratories from around the world are presented for a successful certification of uranium isotope ratios in uranium ore concentrate certified reference materials from the National Research Council Canada. Different mass spectrometric techniques (including SF-ICPMS, q-ICM-MS, TIMS, MC-ICP-MS, SIMS, and AMS) and analytical methods were employed. In general, the reported data from all sources exhibit good consistency, and as expected TIMS and MC-ICP-MS showed superior performances. The three candidate uranium ore concentrate CRMs, UCLO-1, UCHI-1, and UPER-1, have natural uranium isotope ratios with certified values of 0.5304(7)10, 0.5475(2)10, and 0.5361(4)10 for n(U)/n(U) and 0.007 2563(13), 0.007 2563(10), and 0.007 2542(11) for n(U)/n(U), respectively, with expanded uncertainty (k=2) applicable to the last digit of the value given in the parentheses. Information values for n(U)/n(U) in these three CRMs, measured by AMS, are also provided: 1010, 210, and 2210. The uncertainties of the proposed certified values of uranium isotope ratios in uranium ore concentrate CRMs are superior to available reference materials and the values of n(U)/n(U) and n(U)/n(U) show significant variation among the three CRMs.