"Properties and Structure of Vitrified Iron Phosphate Nuclear Wasteform" by G. K. Marasinghe, Mevlüt Karabulut et al.
 

Properties and Structure of Vitrified Iron Phosphate Nuclear Wasteforms

Abstract

The structure of vitreous iron phosphates containing up to 35 wt% of one or more common nuclear waste components such as Na2O, Cs2O, SrO, UO2 or Bi2O3 have been investigated using Fe-57 Mössbauer, X-ray absorption, X-ray photoelectron and Raman spectroscopies and high energy X-ray and neutron diffraction techniques. The glass samples investigated were prepared by melting appropriate chemicals in air at approximately 1200°C for 2 h in alumina crucibles. The chemical durability of the glasses was investigated by measuring their dissolution rates in distilled water at 90°C using the product consistency test (PCT) methodology. The chemical durability of these glasses is characterized by dissolution rates of 10−10-10−11 g/cm2/min. The Mössbauer spectra indicate the presence of both Fe(II) and Fe(III). However, the maximum Fe(II) fraction, Fe(II)/[Fe(II) + Fe(III)], was 0.34. X-ray absorption data show that, on average, both species of iron ions are coordinated with approximately 5 near neighbor oxygens and that the iron-oxygen coordination is only slightly (<10%) influenced by the type or the concentration of the waste elements. Iron ions are also coordinated with 4-6 phosphorous ions in the second shell. Only a minority of the oxygen ions, about 22%, take part in bridging -P-O-P- bonds. Raman spectra show that the phosphorous-oxygen network, which is dominated by (P2O7)4− dimer units, in different samples are similar.

Department(s)

Materials Science and Engineering

Sponsor(s)

United States. Department of Energy

Keywords and Phrases

P150; R110; S440; X120; X130

International Standard Serial Number (ISSN)

0022-3093; 1873-4812

Document Type

Article - Journal

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 2000 Elsevier, All rights reserved.

Publication Date

01 Mar 2000

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