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Structural Changes Around Uranium at the Surface of Waste Glasses Caused by Leaching

Published online by Cambridge University Press:  28 February 2011

N.T. Barrett ,
G.M. Antonini ,
F.R. Thornley ,
G.N. Greaves  and
A. Manara
N.T. Barrett
Affiliation:
Physics Division, Joint Research Centre, 21020 Ispra (Va) -, Italy
G.M. Antonini
Affiliation:
GNSM and Dipartimento di Fisica, Universitã di Modena, 41100 Modena -, Italy
F.R. Thornley
Affiliation:
Department of Physics and Applied Physics, University of Strathclyde, Glasgow G4 ONG, United Kingdom
G.N. Greaves
Affiliation:
SERC, Daresbury Laboratory, Warrington WA4 4AD, United Kingdom
A. Manara
Affiliation:
Physics Division, Joint Research Centre, 21020 Ispra (Va) -, Italy
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Abstract

Structural changes occurring at the surface of leached borosilicate glasses containing 3%wt of uranium have been investigated using fluores- cence EXAFS spectroscopy at grazing incidence. X-ray penetration depths between 30 Å and above 1000 Å are possible by varying the incidence angle of the X-ray monochromatic radiation in the vicinity of the critical angle for total external reflection, øc. This enables the surface and bulk structure to be compared. It is found that a local increase in uranium concentration takes place near the surface of the glass during the first 30 minutes of leaching time. Uranium is coordinated with oxygen and other uranium atoms. The local distribution can be modelled by a square planar island structure comprised of uranyl-type units. This structure changes with corrosion time. After 30 minutes of leaching there is evidence of partial removal of the surface layer.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 84: Symposium L – Scientific Basis for Nuclear Waste Management X , 1986 , 571
Copyright
Copyright © Materials Research Society 1987

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References

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