Age Dating of Individual Micrometer-Sized Uranium Particles by Secondary Ion Mass Spectrometry: An Additional Fingerprint for Nuclear Safeguards Purposes

Abstract

A direct and simultaneous analysis of the age and isotopic composition of nuclear material at the particle scale is described in this study. By comparison with other conventional techniques such as inductively-coupled plasma mass spectrometry or thermal-ionization mass spectrometry, secondary ion mass spectrometry enables one to determine the ages of individual particles in a mixture of nuclear materials. Having access to the purification date can give precious information on the history of a nuclear facility or nuclear material for safeguarding purposes. The high sensitivity of this technique combined with its imaging capabilities enables one to detect and to sort out all particles according to their isotopic composition in one analysis. The succession of two microbeam analyses on an individual particle allows the determination of the precise U abundance and the model age. The methodology was successfully applied to a mixture of uranium particles coming from certified reference material with aU abundance ranging from 10% to 97%: the accuracy on the U abundance is greater than 0.5% and the accuracies on theU abundance and the model age are better than 0.5% and 3%, respectively.

Commissioning Plan for the Cameca NanoSIMS 50L

“…For example, particle morphology can be a diagnostic tool in determining particle origin and history (e.g., Bowen et al, 2013). For SIMS analysis in support of nuclear forensics, there have been efforts to use the technique to determine particle bulk composition (e.g., Betti et al 1999;Park et al 2017;Donohue et al 2008), F content (Kips et al 2007;Kips and Kristo 2009;, O isotope composition (Tamborini et al 2002(Tamborini et al , 2002bPajo et al 2001), and particle age (Faure and Dalger 2017;Wallenius et al 2001). It is generally well understood that uranium and plutonium oxide particles collected during environmental sampling campaigns can contain impurities that are readily observable using energy dispersive spectroscopy (EDS) or X-ray diffraction (XRD) (e.g., Ranebo et al 2007;Torok et al 2004).…”

“…There will likely be further investigation into these issues. In contrast, several studies (Wallenius et al 2001;Faure and Dalger 2017;Tamborini et al 2002b) report on successful attempts to combine particle radiometric age-dating with actinide isotope fingerprinting during SIMS analysis. Age dating of actinide microparticles relies on accurate determination of the 230 Th/ 234 U, 238 Pu/ 234 U, 239 Pu/ 235 U, 240 Pu/ 236 U, 241 Pu/ 241 Am, and 242 Pu/ 238 U ratios (e.g., Tamborini et al 2002b), with the most reliable age constraints arising out of determining ages using multiple parent-daughter systems to identify situations where the primary assumptions needed to reliably interpret the calculated ages (e.g., closed-system behavior, initial amount of daughter product, etc.)…”

“…Another relatively common method of transferring material from environmental swipe samples onto the SIMS analytical substrate is vacuum impaction (e.g., Faure et al 2014;Hedberg et al 2011;Esaka et al 2007Esaka et al & 2009Faure and Dalger 2017;Faure et al 2014;Park et al 2017;Ranebo et al 2010). Vacuum impaction is sometimes known to result in low particle recovery efficiency because many of the particles removed from the swipe may not remain electrostatically adhered to the analytical substrate (typically a carbon planchet).…”

“…Vacuum impaction is sometimes known to result in low particle recovery efficiency because many of the particles removed from the swipe may not remain electrostatically adhered to the analytical substrate (typically a carbon planchet). Therefore, some researchers have adopted the approach of coating the substrate with an adhesive substance (e.g., Faure et al 2014;Faure and Dalger 2017) or grease (Esaka et al 2004(Esaka et al & 2007bPark et al 2017) or transferring the particles onto an adhesive medium (e.g., carbon tape; Ranebo et al 2010) by vacuum impaction. Esaka et al (2004) performed a series of experiments to determine the effect of grease coating on the transfer of particles by vacuum impaction from swipe samples onto a silicon wafer for SIMS analysis.…”

Measurement of production date (age) of nanogram amount of uranium

“…due to the higher contribution from the background. Age dating of U particles by secondary ion mass spectrometry (SIMS) would require relatively large particles (micrometer-sized) of an old material [13].…”