Determination of the Relative Amount of Fluorine in Uranium Oxyfluoride Particles using Secondary Ion Mass Spectrometry and Optical Spectroscopy
Both nuclear forensics and environmental sampling depend upon laboratory analysis of nuclear material that has often been exposed to the environment after it has been produced. It is therefore important to understand how those environmental conditions might have changed the chemical composition of the material over time, particularly for chemically sensitive compounds. In the specific case of uranium enrichment facilities, uranium-bearing particles stem from small releases of uranium hexafluoride, a highly reactive gas that hydrolyzes upon contact with moisture from the air to form uranium oxyfluoride (UO{sub 2}F{sub 2}) particles. The uranium isotopic composition of those particles is used by the International Atomic Energy Agency (IAEA) to verify whether a facility is compliant with its declarations. The present study, however, aims to demonstrate how knowledge of time-dependent changes in chemical composition, particle morphology and molecular structure can contribute to an even more reliable interpretation of the analytical results. We prepared a set of uranium oxyfluoride particles at the Institute for Reference Materials and Measurements (IRMM, European Commission, Belgium) and followed changes in their composition, morphology and structure with time to see if we could use these properties to place boundaries on the particle exposure time in the environment. Because the rate of change is affected by exposure to UV-light, humidity levels and elevated temperatures, the samples were subjected to varying conditions of those three parameters. The NanoSIMS at LLNL was found to be the optimal tool to measure the relative amount of fluorine in individual uranium oxyfluoride particles. At PNNL, cryogenic laser-induced time-resolved U(VI) fluorescence microspectroscopy (CLIFS) was used to monitor changes in the molecular structure.
- Research Organization:
- Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 966537
- Report Number(s):
- LLNL-PROC-414029; TRN: US0904053
- Resource Relation:
- Conference: Presented at: INMM Annual Meeting, Tucson, AZ, United States, Jul 12 - Jul 16, 2009
- Country of Publication:
- United States
- Language:
- English
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Determination of the Relative Amount of Fluorine in Uranium Oxyfluoride Particles Using Secondary Ion Mass Spectrometry and Optical Spectroscopy
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Related Subjects
SAFEGUARDS AND PHYSICAL PROTECTION
38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEAR CHEMISTRY
CHEMICAL COMPOSITION
CRYOGENICS
FLUORESCENCE
FLUORINE
HUMIDITY
IAEA
ISOTOPE SEPARATION
MASS SPECTROSCOPY
MOISTURE
MOLECULAR STRUCTURE
MONITORS
MORPHOLOGY
OXYFLUORIDES
SAMPLING
SPECTROSCOPY
URANIUM
URANIUM HEXAFLUORIDE