Critical need for plutonium and uranium isotopic standards with lower uncertainties

Abstract

Schematic of a Thermal Ionization Mass Spectrometer (TIMS) Instrument.

Atomic spectrometry update – a review of advances in environmental analysis

“…on 26 Mg/24 Mg isotope ratios in matrix-rich natural waters was achieved with an analysis time of 18 minutes per replicate, comparable to the precision obtainable with off-line matrix separation methods. The use of DGT samplers, typically used to obtain time-weighted average concentration in bodies of water, was tested 145 under controlled conditions in a clean room to ascertain whether accurate Pb and Zn isotope ratios could be obtained.…”

“…Both materials are now available as NIST SRM 2786 (fine atmospheric particulate matter (mean particle diameter <10 µm) and NIST SRM 2787 (fine atmospheric particulate matter (mean particle diameter <2.5µm). The status of Pu and U isotopic particulate standards available from NBL was reviewed 24 and suggestions made for future requirements. Such CRMs are a prerequisite for ensuring the quality of measurements in key areas such as nuclear forensics, safeguarding and nonproliferation operations, but improvements in accuracy and precision now attainable with modern MC-ICP-MS cannot be fully exploited because of the large uncertainties associated with some existing NBL materials.…”

Recent Advances in Nuclear Forensic Chemistry

“…There is a growing need within the nuclear forensic community for particulate uranium- and plutonium-based CRMs with a known isotopic composition, as most current CRMs for nuclear forensic applications are only available as bulk materials. ,− Without microanalytical control measurements on independently verified and standardized particulate materials, forensic analysis of seized nuclear materials could potentially be deemed inadmissible in certain courts. , Production of these standard materials relies upon the development of controllable synthetic routes, which are in turn dependent upon a mechanistic understanding of the formation processes. Within the past few years, a relatively large amount of progress in this realm has led to the discovery of new or substantially improved processes to synthesize these nanomaterials − and has also resulted in significant improvements for their characterization.…”

High-Precision Measurement of the 238Pu/239Pu Isotope Ratio by TIMS

“…14−19 In the 1970s, the National Bureau of Standards (NBS) certified isotopic standards using this method with state-of-the-art instruments available at that period. 20 However, advancements in instrumentation now yield within-run precision lower than certified uncertainties. In addition, there is better understanding of the uncertainty budget estimation of the adopted analytical methodology prescribed by the JCGM (Joint Committee for Guides in Metrology) GUM (Guide to the Expression of Uncertainty in Measurement)-6:2020, and due to the exhaustion of the prepared isotopic standard, the practice of recertification of the isotopic standards is often being followed.…”