article posted 24 March 2016
Jamie Weaver is a PhD candidate in the division of Analytical, Environmental, and Radiochemistry in the Department of Chemistry at Washington State University, and is a PhD intern at Pacific Northwest National Laboratory. Her current research interests span the fields of nuclear chemistry, analytical methods for solid-state systems, glass science, archaeology, and ancient history. She has a B.A. in Art Conservation from the University of Delaware and a B.S. in Physical Science from Washington State University. Ms. Weaver’s PhD dissertation project investigates the localized chemistry of 99Tc in nuclear waste glasses. In addition to this work she has collaborated on two studies that correlate the alteration of man-made ancient glass analogues to modelling the long-term durability of nuclear waste glasses. In 2015 she was awarded the Golding Family Fellowship for Women in Science at Washington State University for her research on the alteration of ancient glasses.
Chemometric Determination of the Localized Chemistry of 99Tc in Vitrified Nuclear Waste Glasses
Jamie Weaver1,2, Chuck Soderquist2, Nathalie Wall1, and John McCloy3
1. Washington State University, Department of Chemistry, Pullman, WA, USA
2. Pacific Northwest National Laboratory, Richland, WA, USA
3. Washington State University, Department of Architecture and Engineering, Pullman, WA, USA
Understanding the localized chemistry of 99
Tc in nuclear waste glass is important to developing an efficient glass vitrification process for the Low activity waste (LAW)
at Hanford, WA and other international vitrification facilities. In previous studies it has been determined that the two most common oxidation states of Tc in these glasses are Tc(VII)
and Tc(IV). However, further assessment of the localized chemistry of Tc in the glasses has been limited due to a dearth of published data on pure Tc compounds. Through the development,
characterization, and comparison of a series of alkali-Tc-oxide materials, including alkali pertechnetates and higher order alkali technetium (VII) oxides, to Tc bearing glasses it has now become
possible to more accurately probe the chemistry of Tc in waste glasses. Furthermore, application of chemometrics, specifically Linear Combination Fitting and Principal Component Analysis
, to spectroscopic data Tc glasses has provided insight into a possible mechanism for the incorporation and volatilization of Tc into nuclear waste glasses.
Figure 1 –Principal component analysis of XANES spectra from Tc bearing waste glasses of variable concentrations suggest the presence of 2 or 3 independent components in each glass. (Image created in Athena).