title: Measurement of (233)U/(234)U ratios in contaminated groundwater using alpha spectrometry.
abstract: The uranium isotope (233)U is not usually observed in alpha spectra from environmental samples due to its low natural and fallout abundance. It may be present in samples from sites in the vicinity of nuclear operations such as reactors or fuel reprocessing facilities, radioactive waste disposal sites or sites affected by clandestine nuclear operations. On an alpha spectrum, the two most abundant alpha emissions of (233)U (4.784 MeV, 13.2%; and 4.824 MeV, 84.3%) will overlap with the (234)U doublet peak (4.722 MeV, 28.4%; and 4.775 MeV, 71.4%), if present, resulting in a combined (233+234)U multiplet. A technique for quantifying both (233)U and (234)U from alpha spectra was investigated. A series of groundwater samples were measured both by accelerator mass spectrometry (AMS) to determine (233)U/(234)U atom and activity ratios and by alpha spectrometry in order to establish a reliable (233)U estimation technique using alpha spectra. The Genie™ 2000 Alpha Analysis and Interactive Peak Fitting (IPF) software packages were used and it was found that IPF with identification of three peaks ((234)U minor, combined (234)U major and (233)U minor, and (233)U major) followed by interference correction on the combined peak and a weighted average activity calculation gave satisfactory agreement with the AMS data across the (233)U/(234)U activity ratio range (0.1-20) and (233)U activity range (2-300 mBq) investigated. Correlation between the AMS (233)U and alpha spectrometry (233)U was r(2) = 0.996 (n = 10).
authors.affiliation: Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW 2234, Australia. Electronic address: jjh@ansto.gov.au.
authors.forename: Jennifer J
authors.initials: JJ
authors.lastname: Harrison
authors.affiliation: Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW 2234, Australia.
authors.forename: Timothy E
authors.initials: TE
authors.lastname: Payne
authors.affiliation: Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW 2234, Australia.
authors.forename: Kerry L
authors.initials: KL
authors.lastname: Wilsher
authors.affiliation: Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW 2234, Australia.
authors.forename: Sangeeth
authors.initials: S
authors.lastname: Thiruvoth
authors.affiliation: Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW 2234, Australia.
authors.forename: David P
authors.initials: DP
authors.lastname: Child
authors.affiliation: Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW 2234, Australia.
authors.forename: Mathew P
authors.initials: MP
authors.lastname: Johansen
authors.affiliation: Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW 2234, Australia.
authors.forename: Michael A C
authors.initials: MA
authors.lastname: Hotchkis
mesh_terms: D060587:Groundwater / Q000032:analysis*; D011834:Radiation Monitoring / Q000379:methods*; D013057:Spectrum Analysis; D014501:Uranium / Q000032:analysis*; D014875:Water Pollutants, Radioactive / Q000032:analysis*
chemical_list: D014875:Water Pollutants, Radioactive; D014501:Uranium
keywords: Accelerator mass spectrometry; Alpha spectrometry; Genie™ 2000; Peak deconvolution; Uranium ratio; Uranium-233