Frederic Poineau

Ph. D. Radiochemistry
Laboratory Subatech, Nantes France

Post-doctoral researcher, UNLV Radiochemistry Program

Fundamental technetium chemistry in dimer systems and waste forms

My research focuses on the synthesis and characterization of technetium polymer, with a special interest in compounds with a Tc-Tc  quadruple bond. We have synthesized and studied the dimers Tc₂X₈^2-( X = Cl, Br) . For the first time, these compounds were studied by XAFS and the Tc-Tc distance in Tc₂Br₈^2- was measured. Using  these species as precursors, we plan to synthesize new Tc polymers. The complexation of the octahalogeno-ditechnetate compounds with ligand such as cyanide, phosphine and amine is envisaged. The analysis of these compounds by XRD, UV-Vis, IR, NMR and XAFS spectroscopy will provide new element to better understand the chemistry of Technetium.

The applied research relates to waste forms for ⁹⁹Tc. The isotope ⁹⁹Tc (b^- emitter, T_1/2= 2x10⁵ years) represent one of the most abundant fission product. In the context of a repository, different technetium waste forms are considered and our research will examine the development of Tc alloys.  This research is performed in collaboration with Los Alamos National Laboratory and is supported by the DOE Advanced Fuel Cycle Initiative

Ph. D. Chemistry
University of California, Irvine

Post-doctoral researcher, UNLV Radiochemistry Program

Cynthia Gong

Ph.D. Chemistry, University of California, Berkeley

B.S. Chemistry, California Institute of Technology

Actinide Separations:  Fundamental actinide-organic ligand interactions

The Actinide Group focuses on understanding the fundamental chemistry of the radioactive elements; the Separations subgroup concentrates on the speciation and behavior of actinides in the fuel cycle.  We have developed small-scale, high-throughput techniques for the study of third phase formation in the extraction step of fuel reprocessing.  Representative samples have been studied with FT-IR, XAFS, and UV-vis spectroscopies and analyzed chemically.  Lately I have focused on the speciation of uranyl with acetohydroxamic acid (AHA), an organic reductant used in the fuel cycle that complexes with uranyl in solution and in the solid phase.  These complexes have been extensively studied as a function of pH and AHA concentration using UV-vis in the solution phase as well as XAFS, UV-vis, and FT-IR in the solid phase.  We are developing capabilities to further elucidate the solution-phase speciation using NMR, laser fluorescence, and Raman spectroscopies, and the solid structure using XRD.  As part of the mission of the Advanced Fuel Cycle Initiative, I work with students to develop their radiochemistry and laboratory skills, and teach classes in chemistry.