Results of the REIMEP-17 and NUSIMEP-8 Inter-laboratory Comparison

摘要

Confidence in measurement results is established via reference materials, reference measurements and inter-laboratory comparisons. The Institute for Reference Materials and Measurements of the Joint Research Centre of the European Commission (EC-JRC-IRMM) has a long time experience in the development of nuclear isotopic reference materials and in the organisation of inter-laboratory comparisons (ILCs) in compliance with the respective international ISO guides. The Regular European Inter-laboratory measurement Evaluation Programme (REIMEP) was established at IRMM in 1982 for carrying out external quality control of the measurements for the elements characteristic of the nuclear fuel cycle, while the Nuclear Signatures Inter-laboratory Measurement Evaluation Programme (NUSIMEP) aims to provide test samples for the measurement of trace amounts of nuclear material in environmental matrices. Participants in REIMEP/NUSIMEP can benchmark their measurement results against independent and traceable reference values, assessing their measurement capabilities in line with international or national quality goals. The REIMEP-17 and NUSIMEP-8 certified test samples were prepared from dissolution of mixed oxide fuel in nitric acid and addition of natural uranium. In REIMEP-17 laboratories received two test samples with undisclosed values of the U, Pu amount content and U and Pu isotope amount ratios. The certified test sample REIMEP-17A had a concentration typical for undiluted input solution whereas REIMEP- 17B was a diluted fraction thereof. The NUSIMEP-8 certified test sample was prepared by further gravimetrical dilution of REIMEP-17B. Measurement of the n(~(235)U)(~(238)U) and n(~(240)Pu)(~(239)Pu) ratios were obligatory while the measurement of other ratios were optional. Laboratories were asked to apply their routine analytical procedures and report the results with associated measurement uncertainty. The participant results have been evaluated against the independent certified reference value by means of z and zeta scores in compliance with ISO 13528:2005. In general, the REIMEP-17 results were satisfactory and in compliance with the International Target Values for Measurement Uncertainties in Safeguarding Nuclear Materials (ITV2010). The NUSIMEP-8 results were overall satisfactory and met the International Atomic Energy Agency Measurement Quality Goals (IAEA-SGAS-QC) for the analysis of bulk environmental samples.