12 Search Results

Accurate actinide measurements are critical within the field of nuclear science. Traditional methods for actinide quantification require time-consuming sample processing prior to analysis. There is a need for rapid analytical techniques that still maintain a high degree of accuracy. In this work, actinide reactivity was assessed for multiple oxygen-containing reaction gases using quadrupole inductively coupled plasma tandem mass spectrometry (Q-ICP-MS/MS) to evaluate actinide analysis in complex sample matrices without analyte-matrix separation. A novel method was developed to measure ²⁴¹Am/²⁴¹Pu in complex sample matrices using O₂/He reaction gas with no matrix removal or analyte pre-concentration. This inline method reduces matrix-derived polyatomicmore » interferences that complicate traditional ICP-MS analyses by mass-shifting to ²⁴¹Am¹⁶O⁺ and ²⁴¹Pu¹⁶O₂⁺, allowing Am and Pu to be mass separated for simultaneous analysis. While mass shifting is efficient, a small portion of Am⁺ (<1.3%) and Pu⁺ (<1.4%) react to from AmO₂⁺ and PuO⁺, respectively. Therefore, a mass balance approach was used, in combination with reactivity determined from ²⁴²Pu and ²⁴³Am standard solutions, to correct for residual ²⁴¹PuO⁺ and ²⁴¹AmO₂⁺. The method was validated by measuring ²⁴¹Am/²⁴¹Pu in Pu isotope standards CRM-136 and CRM-137 (separated in March/April 1970 and February 2022, respectively) in both neat solutions and complex matrices containing diluted soil (NIST SRM 2711a, >1000 µg·g^-1). Method detection limits of 15.9 and 9.6 fg·g^-1 were determined for ²⁴¹Am and ²⁴¹Pu, respectively, and ²⁴¹Am/²⁴¹Pu ratios were measured with accuracies within <3.5%. In conclusion, this work presents the first direct analysis of ²⁴¹Am/²⁴¹Pu in unseparated complex matrices, advancing capabilities for rapid actinide measurements.« less

Detection of radioactive isotopes of polonium is important for understanding natural processes, management and assessment of radioactive waste, and nuclear forensics applications. Further, the most common methods for preparation of polonium samples for alpha spectrometry are electrodeposition and spontaneous deposition which are time consuming. Here, we compare three approaches utilizing rapid microprecipitation from bismuth phosphate, copper sulfide, or tellurium alongside traditional spontaneous deposition methods. From these experiments, results show that copper sulfide microprecipitation recoveries are similar to spontaneous deposition on silver and less time consuming with an approximate five-fold decrease in preparation time, including in the presence of complex matricesmore » like seawater.« less

During nuclear fuel reprocessing, radioiodine, can be released.

This Review summarizes a range of analytical techniques that can be used to detect, quantify, and/or distinguish between isotopes of iodine (e.g., long-lived ¹²⁹I, short-lived ¹³¹I, stable ¹²⁷I). One reason this is of interest is that understanding potential radioiodine release from nuclear processes is crucial to prevent environmental contamination and to protect human health as it can incorporate into the thyroid leading to cancer. It is also of interest for evaluating iodine retention performances of next-generation iodine off-gas capture materials and long-term waste forms for immobilizing radioiodine for disposal in geologic repositories. Depending upon the form of iodine (e.g., molecules,more » elemental, and ionic) and the matter state (i.e., solid, liquid, and gaseous), the available options can vary. In addition, several other key parameters vary between the methods discussed herein, including the destructive vs nondestructive nature of the measurement process (including in situ vs ex situ measurement options), the analytical data collection times, and the amount of sample required for analysis.« less

Post-detonation nuclear forensics capabilities depend on the ability to rapidly isolate radionuclides to improve measurement quality. In this work an extraction chromatography resin was developed utilizing the extractants thenoyltrifluoroacetone and 1-octanol supported on Eichrom prefilter resin. Here the resin was tested in nitric and hydrochloric acid matrices. In nitric acid matrices the resin is able to extract zirconium, while in hydrochloric acid matrices it is possible to extract iron and gallium. In all acid conditions tested gold is retained but can be removed from the column with a 10% thiourea rinse.

Understanding the reactivity of metal cations with various reaction gases in ICP-MS/MS is important to determine the best gas to use for a given analyte/interference pair. In this study, nitric oxide (NO) was investigated as the reaction gas following previous experimental designs. The reactions with 50 elements were investigated to examine periodic trends in reactivity, validate theoretical modeling of reaction enthalpies as a method to screen reactant gases, and provide a baseline for potential in-line gas separation methods. ICP-MS/MS studies involving actinides are typically limited to Th, U and Pu, with analyses of Np and Am rarely reported in themore » literature. To date, only two previous methods have investigated the use of NO in ICP-MS/MS analyses. To showcase the utility of NO, a method was developed to measure ²³⁹Pu in the presence of environmental matrix constituent and other actinides, like what could be expected from post-detonation debris, with no chemical separation prior to analysis. ²³⁹Pu⁺ was reacted to form ²³⁹Pu¹⁶O⁺, eliminating interferences derived from the sample matrix by measuring ²³⁹Pu⁺ intensity at m/z = 255 (²³⁹Pu¹⁶O⁺). To validate NO for ²³⁸U¹H⁺ interference removal in environmental matrices, standard reference materials were diluted to 1 mg per gram of solution and spiked to 0.05 pg/g of ²³⁹Pu and 1 µg/g ²³⁸U (Pu/U = 5 x 10^-8). Measured ²³⁹Pu concentrations were within 6% of the spiked value. In conclusion, these results demonstrate that reliable ²³⁹Pu measurements can be made at levels relevant to nuclear forensics without the need for extensive chemical matrix separation prior to analysis.« less

A rapid method to separate Ta, Po, Au, Pt, and W from a sample containing mixed fission and activation products was developed using three commercially available extraction chromatography resins stacked in series. When the separation was tested using all the target activation products, even those with short half-lives were measurable. Finally, combining multiple extraction chromatography resin cartridges in tandem allows for multiple short-lived activation products to be separated from one sample addition without the complication of multiple steps.

Gamma detection of select fission products or activation products such as ¹⁵³Sm and ²³⁹Np in a fission sample is difficult due to gamma interferences from radiotellurium and radioiodine. To aid in the detection of these difficult-to-detect nuclides, the radiotellurium and radioiodine were removed using Cu metal turnings. This method is highly effective at the removal of the interfering radionuclides removing > 98% of the radiotellurium and radioiodine. A mechanistic study was conducted. Determining the deposition mechanism, using a number of techniques including XANES and electrochemistry providing an understanding of the electrochemical path for the Te deposition. Initial work focused onmore » the use of stable Te, further expanding into activated TeO₂, and a fresh fission sample. Importantly, this method presents a rapid method for the direct detection of select fission products that could have a significant impact on nuclear related fields including nuclear forensics.« less

The distribution coefficients of 41 elements were determined on Eichrom’s Actinide resin in HCl and HNO₃ solutions of molarities between 0.01 M and 9 M. Herein a separation scheme for these 41 elements was designed utilizing these distribution coefficients that combines the Actinide resin with Eichrom’s TRU resin. Overall, these values improve the ability to create separations targeting specific analytes utilizing Actinide resin.

Understanding molecular-scale factors governing the precipitation of aluminum hydroxides, such as gibbsite, under alkaline conditions is important for the formation of laterite deposits, as well as aluminum processing. However, mechanisms enabling tetrahedral aluminate ions to assemble into octahedral sites of the gibbsite lattice remain unclear. Formation of oligomeric complexes has been hypothesized as a critical intermediate step. Here, we report a study of gibbsite solubility in highly alkaline solutions using deuterium substitution to probe equilibrium and kinetic factors that could affect oligomeric intermediate formation, including the reactivity and the diffusivity of aluminate ions. When substituting sodium hydroxide with sodium deuteroxide,more » solution analysis shows a nearly 40% and 50% increase in gibbsite solubility in 2.4 and 3.3 mol·kg^–1 total sodium solutions, respectively. Raman spectroscopy indicated that monomeric aluminate ions are the predominant species in solution irrespective of deuteration. However, both ²⁷Al and ²³Na nuclear magnetic resonance (NMR) spectroscopy revealed significant differences in chemical shifts in deuterated solutions, and analysis of ¹H, ²³Na, and ²⁷Al diffusion coefficients with pulsed-field gradient, stimulated echo NMR spectroscopy shows a decrease in ion diffusivity with increasing total deuterium in solution, consistent with the notion of increasing strength in the hydrogen/deuterium bonding network. In conclusion, because the relative change in ¹H diffusion coefficients are commensurate with the difference in apparent solubility constants, there is evidence for an oligomeric intermediate whose steady-state concentration is maintained by the collision frequency of aluminate ions.« less