Preparation and characterisation of uranium and plutonium quality control samples for isotope dilution mass spectrometry measurements and uncertainty estimation

Abstract

This paper presents the preparation, characterisation and validation of two quality control (QC) samples for the measurement of plutonium and uranium contents by isotope dilution mass spectrometry (IDMS). These two QC samples were then used at the JRC-Geel G.2′s laboratory to monitor the performance of IDMS measurement results in line with the ISO 17025 and ISO 17034. The QC samples were prepared from two certified reference materials, namely the NBL-126 (Pu) and CRM 116-A (U). The values for the 235U and 239Pu amount contents of the QC samples were assigned based on the gravimetric preparation of the solutions and verified by independent IDMS measurements. Their use as part of a broader in-house spike inter-calibration campaign, notably during participations in proficiency tests, is also highlighted. Finally, using these two IDMS QC samples, a detailed approach to the IDMS uncertainty evaluation, according to the Guide to the expression of uncertainty in measurement (GUM, 2008) is presented on various examples.

Atomic spectrometry update: review of advances in the analysis of metals, chemicals and materials

“…The ID-MDG-sNP-ICP-TOF-MS approach was used for the size determination of three different sizes of Pt NPs (50 nm, 63 nm, 70 nm diameter) and the results compared with those obtained using sNP-ICP-TOF-MS and TEM. Aer optimisation of the system such that the measured 194 Pt : 195 Pt isotope ratio was approximately 6 the NP sizes measured with the two approaches were 42 nm AE 1 nm and 62 nm AE 1 nm for the nominally 50 and 70 nm NPs with the difference being ascribed to particle degradation during storage. Subsequently, a well characterised Pt NP of 63 nm diameter was analysed with the results obtained being in statistical agreement at 64 AE 1 nm.…”

“…In another study, U and Pu quality control samples for IDMS were developed from two CRMs at JRC Geel in line with ISO 17025 and ISO 17034. 195 The materials CRM 126 ( 239 Pu) and CRM 116-A ( 235 U) were first cleaned to remove any surface oxide layer and then dissolved in 6 M HCl (for Pu) and 8 M HNO 3 (for U). The materials were then diluted to give a U concentration of 3 mg g −1 and a Pu concentration of between 1.5 and 2 mg g −1 .…”

30 years of IRMM-1027 reference materials for fissile material accountancy and control: development, production and characterisation

“…Isotopic standards (Pu IRMM-290b/A3, U IRMM-074/10) are measured to correct for these mass fractionation effects and to ensure the traceability to the International System of Units (SI). Quality control (QC) samples are measured to check the performance of the mass spectrometer and the IDMS method [55].…”

“…The uncertainties of the 239 Pu measurement results are consistent among the different batches. From the IRMM-1027t batch on, a quality control (QC) sample is measured together with the samples, under the same operating conditions [55]. For the 235 U measurement results, IRMM-1027u has slightly larger uncertainty compared to the IRMM-1027s and IRMM-1027t because of an additional uncertainty component coming from the QC sample.…”

Precise determination of 244Cm by 244Cm/239Pu alpha ratio measurements

“…The vast experience of ID-MS collected in nuclear safeguards analyses of uranium and plutonium materials shows that this method is capable to determine Pu and U content with uncertainties of around 0.12 and 0.08% ( k = 2), respectively. 10…”