2014 GSA Annual Meeting in Vancouver, British Columbia (19–22 October 2014)

Paper No. 33-3
Presentation Time: 9:30 AM

SEPARATION OF GLASS PHASES WITHIN TRINITITE USING NF3: DEVELOPING METHODOLOGIES FOR SOURCE ATTRIBUTION


KOEMAN, Elizabeth C.1, MCNAMARA, Bruce K.2, SMITH, Frances N.2, MANA, Sara3, DONOHUE, Patrick4, SIMONETTI, Antonio4 and BURNS, Peter C.3, (1)Department of Civil and Environmental Engineering and Earth Sciences, University of Notre Dame, 156 Fitzpatrick Hall, Notre Dame, IN 46556, (2)Pacific Northwest National Laboratory, PO Box 999, Richland, WA 99352, (3)Civil and Environmental Engineering and Earth Sciences, University of Notre Dame, 301 Stinson Remick Hall, Notre Dame, IN 46556, (4)Civil and Environmental Engineering and Earth Sciences, University of Notre Dame, 156 Fitzpatrick Hall, Notre Dame, IN 46556

Trinitite is post-detonation material produced from the world’s first nuclear bomb explosion on July 16, 1945 at White Sands Missile Range, New Mexico. The plutonium implosion device was detonated atop a 30 m steel tower over the sandy desert at ground zero. The heat from the explosion melted the arkosic sand along with bomb components and the infrastructure present at the site. When re-solidified, an extremely heterogeneous melt glass was produced that is silica-rich due to the melting of the predominant minerals of quartz and feldspars present within the desert sand. Trinitite glass also contains anthropogenic material, such as metals from the steel tower (Fe, Co, Cr), device components (U, Pb), and wiring (Cu) as well as remnants of the Pu fuel.

This study focuses on the separation of solid components (i.e., glass, remnant minerals, and anthropogenic materials) of Trinitite using a nitrogen trifluoride (NF3)-based thermal treatment. Prior to the latter, samples were characterized fully for their major and trace elemental abundances. Subsequent to the NF3 treatment, samples were imaged by scanning electron microscopy in order to document changes in grain size and morphology, and energy dispersive spectroscopy was performed to determine changes in major element abundances. Preliminary results demonstrate that mass loss occurs at different rates for each sample, but each sample experienced an expected large decrease in Si content (resulting from volatilization of SiF4). Within the residual material, the concentration of metals increases due to the background matrix (Si) being volatilized. Fluorinated samples will be further analyzed for trace element abundances and isotopic (U, Pu) compositions via solution mode ICP-MS, and these results will be compared to their pre-fluorinated counterparts. The ultimate goal of our investigation is to develop a relatively rapid method for the effective separation of bomb components from complex matrices resulting from a nuclear explosion. This methodology will result in enhanced source attribution capabilities and increased nuclear security at the global scale.