NUSIMEP-6: Uranium Isotope Amount Ratios in Uranium Particles

The IRMM Nuclear Signatures Interlaboratory Measurement Evaluation Programme (NUSIMEP) is an external quality control program organised by IRMM with the objective of providing materials for measurements of trace amounts of nuclear materials in environmental matrices. Measurements of the isotopic ratios of the elements uranium and plutonium in small amounts, such as typically found in environmental samples, are required for nuclear safeguards, for the control of environmental contamination and for the detection of nuclear proliferation. Participants in NUSIMEP compare their reported measurement results with independent external certified reference values with demonstrated traceability and uncertainty, as evaluated according to international guidelines. NUSIMEP-6 focused on measurements of Uranium Isotope amount rations in uranium particles aiming to support laboratories involved in uranium particles analysis. It was the first NUSIMEP on particle analysis and particularly also organised for the IAEA network of analytical laboratories of environmental sampling (NWAL) as part of the IRMM activities in the frame of the EC support programme to IAEA. The NUSIMEP test samples were prepared by controlled hydrolysis of well certified uranium hexafluoride in an aerosol deposition chamber at IRMM. Participating laboratories in NUSIMEP-6 received a test sample of uranium particles on a graphite planchet with undisclosed isotope amount ratios values n(234U)/n(238U), n(235U)/n(238U) and n(236U)/n(238U). The uranium isotope amount ratios were to be measured using their routine analytical procedures. Measurement of the major ratio n(235U)/n(238U) was obligatory; measurements of the minor ration n(234U)/n(238U) and n(236U)/n(238U) were optional. 15 Institutes reported measurement results, among those 7 NWAL laboratories. The analytical methods applied were SIMS, (FT)-TIMS, LA-ICP-MS and alpha spectrometry. The participants' measurement results were evaluated against the certified reference values. The results of NUSIMEP-6 confirm the capability of laboratories in measuring the major ratio n(235U)/n(238U) in uranium particles. More difficulties were observed for the minor isotope ratios n(234U)/n(238U) and n(236U)/n(238U). In addition feedback from the participants was collected in view of improvements and optimisation of future NUSIMEP interlaboratory comparisons for uranium isotope amount ratios.

TRUYENS Jan;  AREGBE Yetunde;  KIPS Ruth;  RICHTER Stephan;  STEFANIAK Elzbieta;  KUEHN Heinz;  KRAIEM Monia; 

2009-11-16

ESARDA and the Joint Research Centre of the European Commission

JRC53598

https://publications.jrc.ec.europa.eu/repository/handle/JRC53598,