Update on Isotope Reference Materials and Measurements for Nuclear Safeguards at IRMM

The European Commission's Institute for Reference Materials and Measurements is tasked for providing isotope reference materials and reference measurements not only to the EU member states but even to the entire international safeguards community. This does not only include various types of specific and tailor-made reference materials but also the development of new reference measurement methods and their implementation at various safeguards laboratories, e.g. to the IAEA using the EC/IAEA support program, to NBL (New Brunswick Laboratory), LLNL (Lawrence Livermore National Laboratory, both U.S.DOE) and CEA using the respective so-called \"action sheets\" and also to ITU (Institute for Transuranium Elements) within the Joint Research Centre (JRC). This paper gives an overview about the presently available nuclear isotope reference materials and their applications as well as about ongoing projects for new materials and plans for the future. Secondly an overview about mass spectrometric reference methods developed and utilized at IRMM will be given. This includes, e.g., the double standard method for isotope measurements using UF6 gas, for which a new mass spectrometer will be installed in 2010, furthermore the total evaporation and modified total evaporation methods for TIMS, the filament carburization technique for low-level TIMS (Thermal Ionization Mass Spectrometry), single uranium particle measurements, etc. As an example the joint development and implementation of the modified total evaporation method will be reviewed. This method is implemented within the nuclear safeguards community through a collaboration of some \"key nuclear safeguards laboratories\", namely NBL, IAEA/SGAS, ITU and IRMM with Thermo Fisher Scientific (manufacturer of the TRITON TIMS), with IRMM taking the initiative and the leading role.