Verification Strategies and Results for the New Synthetic Uranium Isotopic Mixtures at IRMM

Several new sets of synthetic isotope reference materials for instrument calibration have been developed at IRMM based on proven methods of purifying and mixing highly enriched oxides. For an absolute calibration of 235U/238U ratio measurements two types of synthetic mixtures were prepared. First the IRMM-3020-3090 set of primary isotopic mixes with 20%, 35%, 50%, 75% and 90% 235U enrichment was made. Secondly also a much awaited double spike IRMM-3636 with a 233U/236U ratio of 1:1 was prepared which allows internal mass fractionation correction for 235U/238U ratio measurements. For all synthetic isotope mixtures certification is done based on weights, purity and isotopic enrichment of the starting materials. However, a careful verification e.g. by mass spectrometry is necessary. This paper describes the strategy and results for the verification measurement program performed at IRMM based on high precision thermal ionization mass spectrometry.

RICHTER Stephan;  ALONSO MUNOZ Adolfo;  EYKENS Roger;  JAKOBSSON Ulf;  KUEHN Heinz;  VERBRUGGEN Andre;  WELLUM Roger;  KEEGAN Elizabeth; 

2007-12-21

Institute of Nuclear Materials Management

JRC41805