Evaluation of thermally converted silicotitanate waste forms

Y. Su, M. L. Balmer, L. Wang, B. C. Bunker, M. Nyman, T. Nenoff, A. Navrotsky

Research output: Contribution to journalConference articlepeer-review

23 Scopus citations

Abstract

Crystalline silicotitanate ion exchangers are highly selective for separating Cs from Na-rich waste streams. However, use of these ion exchangers for removal of Cs from radioactive tank waste will result in large volumes of secondary wastes. Thermal conversion of silicotitanates produces a durable waste form with reduced volumes up to 40%. Leach tests (MCC-1 and PCT) have shown that Cs leach rates of IE-911-Na (heat treated at 900 °C for an hour) are extremely low, ranging from 0.1 to 1wt% Cs loss in Cs fraction release, or 10-1 to 10-8 g/m2 day in normalized Cs mass loss. These are several orders of magnitude lower than that of borosilicate glass. In order to understand the interplay between the structure and high Cs durability, X-ray diffraction, 133Cs NMR, and thermogravimetric analysis have been used to identify phase(s) responsible for trapping Cs in these silicotitanates. Results indicate that Cs is likely to be contained in a crystalline silicate phase.

Original languageEnglish (US)
Pages (from-to)77-84
Number of pages8
JournalMaterials Research Society Symposium - Proceedings
Volume556
DOIs
StatePublished - 1999
Externally publishedYes
EventProceedings of the 1998 MRS Fall Meeting - Symposium 'Scientific Basis for Nuclear Waste Management XXII' - Boston, MA, USA
Duration: Nov 30 1998Dec 4 1998

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering

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