title: Spatially-resolved analyses of aerodynamic fallout from a uranium-fueled nuclear test.
abstract: Five silicate fallout glass spherules produced in a uranium-fueled, near-surface nuclear test were characterized by secondary ion mass spectrometry, electron probe microanalysis, autoradiography, scanning electron microscopy, and energy-dispersive x-ray spectroscopy. Several samples display compositional heterogeneity suggestive of incomplete mixing between major elements and natural U ((238)U/(235)U = 0.00725) and enriched U. Samples exhibit extreme spatial heterogeneity in U isotopic composition with 0.02 < (235)U/(238)U < 11.84 among all five spherules and 0.02 < (235)U/(238)U < 7.41 within a single spherule. In two spherules, the (235)U/(238)U ratio is correlated with changes in major element composition, suggesting the agglomeration of chemically and isotopically distinct molten precursors. Two samples are nearly homogenous with respect to major element and uranium isotopic composition, suggesting extensive mixing possibly due to experiencing higher temperatures or residing longer in the fireball. Linear correlations between (234)U/(238)U, (235)U/(238)U, and (236)U/(238)U ratios are consistent with a two-component mixing model, which is used to illustrate the extent of mixing between natural and enriched U end members.
authors.affiliation: Glenn T. Seaborg Institute, Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, CA 94550, USA; Department of Nuclear Engineering, University of California, Berkeley, 4113 Etcheverry Hall MC 1730, Berkeley, CA 94720, USA. Electronic address: lewis105@llnl.gov.
authors.forename: L A
authors.initials: LA
authors.lastname: Lewis
authors.affiliation: Glenn T. Seaborg Institute, Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, CA 94550, USA.
authors.forename: K B
authors.initials: KB
authors.lastname: Knight
authors.affiliation: Glenn T. Seaborg Institute, Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, CA 94550, USA.
authors.forename: J E
authors.initials: JE
authors.lastname: Matzel
authors.affiliation: Department of Nuclear Engineering, University of California, Berkeley, 4113 Etcheverry Hall MC 1730, Berkeley, CA 94720, USA.
authors.forename: S G
authors.initials: SG
authors.lastname: Prussin
authors.affiliation: Los Alamos National Laboratory, P.O. Box 1663, Los Alamos, NM 87544, USA.
authors.forename: M M
authors.initials: MM
authors.lastname: Zimmer
authors.affiliation: Los Alamos National Laboratory, P.O. Box 1663, Los Alamos, NM 87544, USA.
authors.forename: W S
authors.initials: WS
authors.lastname: Kinman
authors.affiliation: Glenn T. Seaborg Institute, Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, CA 94550, USA.
authors.forename: F J
authors.initials: FJ
authors.lastname: Ryerson
authors.affiliation: Glenn T. Seaborg Institute, Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, CA 94550, USA.
authors.forename: I D
authors.initials: ID
authors.lastname: Hutcheon
mesh_terms: D054043:Nuclear Weapons; D011834:Radiation Monitoring / Q000379:methods*; D011847:Radioactive Fallout / Q000032:analysis*; D012990:Soil Pollutants, Radioactive / Q000032:analysis*; D062206:Spatial Analysis; D014501:Uranium / Q000032:analysis*
chemical_list: D011847:Radioactive Fallout; D012990:Soil Pollutants, Radioactive; D014501:Uranium
keywords: Device debris; Fallout; Nuclear forensics; SIMS; Trinitite