NUSIMEP-4: Measurement of Uranium Isotopic Abundances in a Simulated Urine Solution

The previous NUSIMEP (‘Nuclear Signatures Inter-laboratory Measurement Evaluation Programme’) campaigns were designed for the measurement of uranium isotopic ratios: in a simple nitrate matrix (NUSIMEP 2) and in a saline solution (NUSIMEP 3). For NUSIMEP 4 it was decided to prepare the uranium in a more realistic matrix, a simulated urine solution. As for the previous campaigns, the uranium samples were prepared by mixing UF6 in the gas phase and measuring n(235U)/n(238U ) in a gas-source mass-spectrometer. Following this the minor isotopic ratios were measured by TIMS calibrated internally by the certified ratio n(235U)/n(238U ). The matrix solution was prepared from a mixture of salts to produce a 2 % saline solution. This was chemically purified from uranium and the remaining trace quantity of this element was measured by ICP-MS. The (natural) uranium in a sample of urea was also measured. The concentrated uranium solutions prepared by hydrolysing the UF6 samples were diluted in cleaned quartz flasks with 1 M HNO3 prepared from sub-boiled nitric acid and mixed with the saline solution and urea to make two solutions with approximately 5 ng Uwg-1 solution. The uranium isotopic vector was certified from the measurements as UF6 and by TIMS, and taking into account the small contribution from blanks from matrix and equipment. The solutions were transported to the participants’ laboratories in cleaned polypropylene bottles. Each laboratory was requested to measure the ratios n(234U)/n(238U), n(235U)/n(238U), n(236U)/n(238U) and to report the measured values with an uncertainty preferably following the ISO/GUM guides. The collected results show a picture of the present status of measurements of uranium isotopes on this level of uranium. A parallel campaign conducted by the CCQM, P-48, will collect measurement results from selected laboratories for similar materials and these results will subsequently be compared with the NUSIMEP 4 results.

STOLARZ Anna;  MOENS Andre;  ALONSO MUNOZ Adolfo;  KUEHN Heinz;  VERBRUGGEN Andre;  EYKENS Roger;  QUETEL Christophe;  PONZEVERA Emmanuel;  WELLUM Roger; 

2006-11-09

EC JRC Ispra (ESARDA)

JRC34136