http://wateriso.utah.edu/waterisotopes/media/isomaps/jpegs/o_global/oma_global.jpg S13: State of the Art Environmental Sample Analysis NOVEL MASS SPECTROMETRIC TECHNIQUES FOR THE RAPID CHARACTERIZATION AND FINGERPRINTING OF NUCLEAR FUEL MATERIALS John Cliff* 1, John Denman 2, Laure Martin 1, Matt Kilburn 1, Thippatai Tanpraphan 3 Goals Results Future Methods Conclusions 1 University of Western Australia 2 University of South Australia 3 International Atomic Energy Agency
http://wateriso.utah.edu/waterisotopes/media/isomaps/jpegs/o_global/oma_global.jpg S13: State of the Art Environmental Sample Analysis GOALS Our primary goal was to explore the novel use of SIMS for elemental, polymer, and oxygen isotope characterization of uranium-bearing environmental particles. Elemental fingerprinting, polymer characterization, and O- isotope analyses may help elucidate provenance, history, and manufacturing processes. Being able to perform these analyses at the micron-scale mitigates the need for radiological controls.
TOF-SIMS fingerprinting: METHODS Oxygen isotope analyses: We used TOF-SIMS elemental analyses of single U-bearing particles combined with principle component analysis (PCA) to differentiate classes of particles. Elemental fingerprinting can help establish particle composition and trace contamination. We also used TOF-SIMS to explore the composition of morphologically distinct particles present in a swipe sample. We used multicollector LG-SIMS to locate and perform 18 O/ 16 O analyses on single U-bearing particles. We used a single U 3 O 8 standard as a reference material (CRM U010) against which the O-isotope ratio of other particles was compared. Oxygen isotope analysis can help determine the location of production because O-isotope values vary worldwide. They may also help us determine means of production. simsworkshop.org
SIMS uses a high-energy primary ion beam to ablate material for introduction into a mass spectrometer. It is one of the most surface-sensitive techniques available and thus can be used to analyze single particles. SIMS For elemental fingerprinting and polymer characterization we used a time of flight SIMS. TOF-SIMS produces a spectrum characteristic of the sample. For O-isotope ratios, we used a largegeometry magnetic sector SIMS. LG- SIMS instruments are optimized for high precision analyses that are necessary to obtain meaningful isotope ratio data. Touch the image on the right to start movie BACK Anal. Chem. 2003, 75, 4402-4407
LOCATION OF PARTICLES Prior to both TOF-SIMS and LG-SIMS particle analyses we were able to locate U-bearing particles using 238 U 16 O (+/-) ion images. Below is an example of results from an automated particle search using LG-SIMS. Each coloured pixel on the left hand image represents a 500 µm 500 µm area where U-bearing particles were found. In the right-hand image, spatially resolved, U-bearing particles are evident in a single 500 µm 500 µm imaged area. BACK
CONCLUSIONS TOF-SIMS fingerprinting and 18 O/ 16 O analysis show promise for revealing forensically useful information from U-bearing particles in environmental samples. Both types of analysis are limited by particle size, however, the advantage of the greatly reduced need for radiological control may make these technologies worth serious development. simsworkshop.org http://wateriso.utah.edu/waterisotopes/media/isomaps/jpegs/o_global/oma_global.jpg
RESULTS Left: TOF-SIMS spectrum of a single U-bearing particle. Characteristic elemental and molecular peaks including U+ UO+ and UO 2 + are apparent. Right: PCA clearly discriminates particle types based on multi-elemental composition. Particles with similar chemical composition are not well separated based on chemical makeup. NEXT
18 O of U020a monodispersed particles relative to U010. Uncertainties are 2 sigma of block to block variability of a single measurement. S13: State of the Art Environmental Sample Analysis RESULTS Right: High-resolution TOF- SIMS analysis reveals that the carrier of the uranium signal in these particles is likely to be a polymer in the nylon family. Peaks in the analysis spectrum (centre-right) not present in the reference spectrum (bottom-right) can be attributed to common contaminants and the primary Ga + beam used to acquire the reference spectrum. NEXT
18 O of U020a monodispersed particles relative to U010. Uncertainties are 2 sigma of block to block variability of a single measurement. S13: State of the Art Environmental Sample Analysis RESULTS Right: 18 O/ 16 O analysis results for single particles. *δ notation refers to deviation of the sample particle 18 O/ 16 O relative to the standard (CRM U010) in parts per thousand ( ). *2 is derived from internal precision of an individual analysis. Although 1 micron particles (U020a mono) are required for 1 external precision, there exists enough variation in δ 18 O to glean information from even smaller particles. Particle δ 18 O* 2 ** 1SD ext U020a mono -20.2 2.6 U020a mono -21.6 2.6 U020a mono -22.2 2.7 U020a mono -20.5 2.7 U020a mono -21.5 2.6 U020a mono -23.4 2.6 U020a mono -23.2 2.7 U020a mono -22.4 2.5 U020a mono -21.4 2.5 U020a mono -22.6 2.7 U020a mono -21.6 2.5 U020a mono -21.7 2.6 1.0
Although these results are intriguing, there is considerable work to be done to validate these techniques. Among these works are: Optimization of analysis protocols Identification of optimum standards Standardization of δ 18 O values to VSMOW Establishment of particle size ranges from which useful data may be gleaned Development of relevant databases to streamline forensic investigations FUTURE simsworkshop.org http://wateriso.utah.edu/waterisotopes/media/isomaps/jpegs/o_global/oma_global.jpg
WORLD MAP OF O-ISOTOPE RATIOS IN PRECIPITATION RELATIVE TO VIENNA STANDARD MEAN OCEAN WATER Oxygen isotopes vary world-wide as a function of temperature and precipitation patterns. Thus, O-isotopes may be useful in establishing provenance of U-oxide samples. Unknown are the effects of production processes and exchange reactions on the O- isotope signatures. BACK http://wateriso.utah.edu/waterisotopes/media/isomaps/jpegs/o_global/oma_global.jpg