The series of IRMM-1027 Large-Sized Dried (LSD) spikes is prepared by the JRC to meet the existing requirements for reliable isotope reference materials for the accountancy measurements of uranium and plutonium by isotope dilution mass spectrometry (IDMS) in compliance with the International Target Values for Measurement Uncertainties in Safeguarding Nuclear Materials (ITVs).
The JRC standards for nuclear safety, security and safeguards unit in Geel is accredited by the Belgian Accreditation Body (BELAC) for the standards ISO/IEC 17025:2017, ISO 17034:2016 and SO/IEC 17043:2010 and thus formally recognised for its technical competence. The IRMM-1027v is the most recent batch of LSD spike reference materials (CRMs) and was produced and certified in compliance with ISO 17034:2016, and ISO Guide 35:2017 applying the knowledge and experience of the last 30 years together with the outcome of exploratory research. Each unit is certified for 235U, 238U, 239Pu masses and uranium and plutonium isotope amount ratios as dried nitrates. The certified values of the LSD spikes were assigned using state of the art analytical techniques and metrological tools such as substitution weighing and Isotope Dilution Thermal Ionization Mass Spectrometry (ID-TIMS). The associated uncertainties were estimated according to the bottom-up approach described in the Guide to the Expression of Uncertainty in Measurement (GUM, JCGM 100:2008), which is the widely acknowledged international consensus for the expression of uncertainty in measurement.
Figure 1. The colour codes represent the two different embedding matrices used for the production: red – CAB/DOP, blue – CMC. Error bars show the relative expanded uncertainties (coverage factors are based on the t-distribution for the associated effective degrees of freedom that corresponds to a level of confidence of about 95 %). Red dotted lines show the combined relative expanded uncertainty assigned to the gravimetric value (coverage factor k = 2 that corresponds to a level of confidence of about 95 %).
Recently, a European patent application was filed on an entire portfolio of organic embedding matrices that will further optimise the characteristics of LSD spikes and other actinide CRMs to meet contemporary demands of policy partners and stakeholders. The provision of the IRMM-1027 series responds to the mandate of the European Commission expressed in the EURATOM Treaty, highly appreciated by European and international nuclear safeguards authorities and laboratories as well as by industry.
The preparation and certification of IRMM-1027v is described in detail in the certification report, available together with the certificate in the online Certified reference materials catalogue.
View the certification report: Preparation and Certification of Large-Size Dried (LSD) Spike: IRMM-1027v
- 23 november 2021