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Abstract

A replacement series of IRMM-072 uranium isotopes 233U, 235U and 238U has been prepared and certified. The new series IRMM-074, follows the design of IRMM-072: the isotopic ratio n(235U)/n(238U) was held constant and the ratio n(233U)/n(235U) was varied from 1.0 to approximately 10-6. The isotopically enriched isotopic uranium materials were purified using identical methods involving separation on anion and cation column followed by a precipitation as peroxide. Each of the three materials were treated in separate clean glove-boxes to eliminate cross-contamination. The oxides were sintered to convert them to U3O8 in parallel, in an oven installed in a glove-box that provided a controlled low-humidity environment. The 233U was dissolved to form a separate solution with the same concentration and from this primary solution three dilutions were made by weighing. Weighed amount of the 235U/238U solution and weighed amounts of the original 233U solution were mixed and made up to a concentration of 0.1 mg•g-1. The final solutions were dispensed into individual quartz ampoules that were subsequently flame-sealed. The uncertainties contributing to the final uncertainties of the isotopic ratios are the weighing errors, the measured impurities in each isotopic material, the stoichiometry of the oxides and the isotopic abundances of each. The main uncertainty is expected to be the measurement of the chemical impurities and for this reason a number of measurement techniques are being employed. The methods for the preparation and mixing will be described and the progress towards certification reported.

Additional information

Authors: VERBRUGGEN A, European Commission, Joint Research Centre, Institute for Reference Materials and Measurements, Geel (BE);ALONSO A, European Commission, Joint Research Centre, Institute for Reference Materials and Measurements, Geel (BE);EYKENS R, European Commission, Joint Research Centre, Institute for Reference Materials and Measurements, Geel (BE);HENDRICKX F, European Commission, Joint Research Centre, Institute for Reference Materials and Measurements, Geel (BE);KEHOE F, European Commission, Joint Research Centre, Institute for Reference Materials and Measurements, Geel (BE);KÜHN H, European Commission, Joint Research Centre, Institute for Reference Materials and Measurements, Geel (BE);RICHTER S, European Commission, Joint Research Centre, Institute for Reference Materials and Measurements, Geel (BE);VAN BAELEN G, European Commission, Joint Research Centre, Institute for Reference Materials and Measurements, Geel (BE);WELLUM R, European Commission, Joint Research Centre, Institute for Reference Materials and Measurements, Geel (BE)
Bibliographic Reference: EUR 22270 EN (2006), 38 pp. Free of charge
Availability: http://bookshop.europa.eu/is-bin/INTERSHOP.enfinity/WFS/EU-Bookshop-Site/en_GB/-/EUR/ViewPublication-Start?PublicationKey=LANA22270 (Catalogue Number: LA-NA-22270-EN-C)
ISBN: ISBN: 92-79-02217-2
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