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Journal of Radioanalytical and Nuclear Chemistry
Authors: Songsheng Jiang, Zhiyuan Chang, Min Zhao, Yonggang Zhao, X. L. Zhao, and W. E. Kieser

Summary  

Under an IAEA project for upgrading of reference materials, a new determination of the 129I concentration in the IAEA-375 reference material was performed. A chemical procedure was set up for the preparation of the AgI samples. Measurement of 129I was carried out using the IsoTrace Tandetron AMS facility at University of Toronto. To ensure the accuracy of the calibration, the tuning of the AMS system was iterated using not only the QC (quality control) samples but also all unknown samples. To minimize any possible current-dependent effects between 129I and 127I ions in the injection magnet, low Cs+ sputtering beam intensity (10 μA) was used. The reproducibility in determining the 129I/127I ratio in the IAEA-375 AgI samples was less than 1%. The activity concentration (C A) of 129I in the IAEA-375 reference material was determined to be 1.59±0.08 mBq . kg-1 at 95% confidence level. The present value is about 7% lower than the IAEA recommended value (1.7 mBq . kg-1) listed in 2000 or 20% lower than the recommended value (2 mBq . kg-1) listed in the IAEA AQCS Reference Material Catalogue (2002-2003). Since the IAEA recommended values for IAEA-375 materials was issued about 10 years ago and error range of the recommended values were large, the results we obtained might be useful in upgrading the recommended value.

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Journal of Radioanalytical and Nuclear Chemistry
Authors: Yan Chen, Zhi-yuan Chang, Yong-gang Zhao, Ji-long Zhang, Jing-huai Li, and Fu-jun Shu

Abstract  

An isotope dilution multicollector inductive coupled plasma mass spectrometry (ID-MC-ICP-MS) method for determining age of trace Pu through measuring 241Pu/241Am, 240Pu/236U ratio was established. At the same time, other two methods-α-spectrometry combined with MC-ICP-MS and liquid scintillator combined with α-spectrometry through measuring 241Pu/241Am ratio to determine the age of trace Pu were also studied. The techniques were explored for the age determination of nanogram grade Pu sample on the basis of Pu/Am, Pu/U separation. The ages of two Pu samples—one with known and the other with unknown age—were determined by the three methods. The determined ages by the three methods were all in agreement with the reference value. The established methods for determining the age of trace Pu could be adopted in the verification activities of nuclear safeguards and nuclear arms control.

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