Confocal {mu}-XRF, {mu}-XAFS, and {mu}-XRD Studies of Sediment from a Nuclear Waste Disposal Natural Analogue Site and Fractured Granite Following a Radiotracer Migration Experiment

Journal Article · Fri Feb 02 04:00:00 EST 2007 · AIP Conference Proceedings

DOI:https://doi.org/10.1063/1.2644469· OSTI ID:21054589

Denecke, Melissa A; Brendebach, Boris; Rothe, Joerg; Simon, Rolf ^[1]; Janssens, Koen; Nolf, Wout de; Vekemans, Bart ^[2]; Falkenberg, Gerald ^[3]; Somogyi, Andrea ^[4]; Noseck, Ulrich ^[5]

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1. Forschungszentrum Karlsruhe, P.O. Box 3640, D-76021 Karlsruhe (Germany)
2. Department of Chemistry, University of Antwerp, Universiteitsplein 1, B-2610 Antwerp (Belgium)
3. Hamburger Synchrotronstrahlungslabor (HASYLAB) at DESY, Notkestr. 85, D-22603 Hamburg (Germany)
4. Synchrotron Soleil, F-91192 Gif-sur-Yvette Cedex (France)
5. Gesellschaft fuer Anlagen- und Reaktorsicherheit (GRS) mbH, Theodor-Heuss-Strasse 4, D-38122 Braunschweig (Germany)

Combined {mu}-XRF, {mu}-XAFS, and {mu}-XRD investigations of a uranium-rich tertiary sediment, from a nuclear repository natural analogue site, and a fractured granite bore core section after a column tracer experiment using a Np(V) containing cocktail have been performed. Most {mu}-XRF/{mu}-XAFS measurements are recorded in a confocal geometry to provide added depth information. The U-rich sediment results show uranium to be present as a tetravalent phosphate and that U(IV) is associated with As(V). Arsenic present is either As(V) or As(0). The As(0) forms thin coatings on the surface of pyrite nodules. A hypothesis for the mechanism of uranium immobilization is proposed, where arsenopyrite acted as reductant of ground water dissolved U(VI) leading to precipitation of less soluble U(IV) and thereby forming As(V). Results for the granite sample show the immobilized Np to be tetravalent and associated with facture material.

• OSTI ID: 21054589
• Journal Information: AIP Conference Proceedings, Journal Name: AIP Conference Proceedings Journal Issue: 1 Vol. 882; ISSN APCPCS; ISSN 0094-243X
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ABSORPTION SPECTROSCOPY
ARSENIC IONS
FINE STRUCTURE
GRANITES
GROUND WATER
NATURAL ANALOGUE
PHOSPHATES
PRECIPITATION
RADIOACTIVE WASTE DISPOSAL
RADIONUCLIDE MIGRATION
SEDIMENTS
SURFACES
TRACER TECHNIQUES
URANIUM
URANIUM IONS
X-RAY DIFFRACTION
X-RAY FLUORESCENCE ANALYSIS
X-RAY SPECTRA
X-RAY SPECTROSCOPY