The use of silver as a selective precipitant for 129I in radioactive waste management

M. (Chemistry) Atkins*, A. Kindness, F. P. Glasser, I. Gibson

*Corresponding author for this work

Research output: Contribution to journalArticle

12 Citations (Scopus)

Abstract

129I is one of the more hazardous nuclides occurring in radioactive waste. In the form of I-, its most likely speciation, it is poorly sorbed on most geologic media. Several workers have suggested the use of silver to precipitate I- as the insoluble AgI, in a cemented waste form, or as a "getter". The efficacy of this procedure is examined by experiment, in conjunction with thermodynamic predictions. The addition of AgNO3 to Portland cement leads to coprecipitation with C-S-H, with low Ag solubilities (∼ 10 μmg/L); 2-;3 orders of magnitude lower than predicted (from Ag2O). AgI is stable in these matrices, with low aqueous I concentrations (<2 mg/L). In 85% BFS-15% OPC pastes, AgI is unstable due to redox and complexation reactions, with much I- passing into solution; concentrations up to 900 mg/L were observed. It is shown that repository conditions, on closure, are also likely to induce solubilisation of I- from AgI. It is concluded that the use of Ag is unlikely to significantly improve the immobilisation properties of the near field for radioiodine.

Original languageEnglish
Pages (from-to)303-308
Number of pages6
JournalWaste Management
Volume10
Issue number4
DOIs
Publication statusPublished - 30 Jul 1990

Keywords

  • silver
  • 129l
  • radioactive waste management

ASJC Scopus subject areas

  • Waste Management and Disposal

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