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The Joint Research Centre (JRC) is the European Commission's science and knowledge service which employs scientists to carry out research in order to provide independent scientific advice and support to EU policy.
The new IRMM-3000 series of reference materials is designed to serve as the ideal set of highly enriched uranium material standards needed for calibrating mass spectrometry measurements of nuclear safeguards samples.
The reduced uncertainty of the 235U enrichment for the IRMM-3000 series reference materials allows a significant improvement of precision and accuracy for the analysis of highly enriched nuclear material. This is needed by nuclear safeguards authorities to monitor the use and prevent the proliferation of highly enriched uranium material, commonly utilized in enrichment facilities, nuclear weapons facilities and for the production of medical isotopes, for example 99Mo for 99mTc generators.
The IRMM-3000 series of uranium nitrate solution reference materials includes five materials with different isotopic compositions, covering a range from 20 % to 90 % for the enrichment of 235U. The preparation and certification of the isotopic composition was performed by gravimetrically mixing calcinated and isotopically pure (>99.95%) base materials of 235U and 238U. This strategy has led to an unprecedented level of 0.02 % (95 % confidence level) for the relative uncertainties of the isotope ratios 235U/238U and the 235U enrichment. The verification of the certified 235U/238U isotope ratios and the characterization of the 234U/238U and 236U/238U isotope ratios were performed by taking advantage of the standardized mass spectrometric measurement procedures ASTM C1871-18 and ASTM C1832-21, respectively.
The preparation and certification of the new IRMM-3000 series of reference materials are described in detail in the certification report:
The IRMM-3000 series can be ordered from the certified reference materials online catalogue of the European Commission's Joint Research Centre (JRC).