Separation, sequestration and storage of the long-lived anionic fission products 99Tc and 129I are problematic due to their environmental mobility (i.e., anionic species) and redox sensitive speciation (e.g., Tc(IV)O2 insoluble versus Tc(VII)O4- aqueous).  Consequently, the separation and sequestration of these two fission products tend to drive waste processing and waste disposal design.  One potential risk mitigation strategy for these fission products is to minimize their release by using sequestration agents. In this work we explored the use of a nanoscale �test-tube and cap� sorbent-based system for the separation and sequestration of anionic fission products in process and environmental waste streams (i.e., nanophase extractors). The nano test-tubes were fabricated using a well-developed silica nano-templating method along with silver solid solution and redox chemistries. Experimentally, the interior of the Si-nanotubes were functionalized with silver (Ag) moieties that are known to be selective for I- and TCO4- removal. Batch sorption studies were then conducted to characterize the sorption behavior of a non-radioactive I- isotope within the functionalized nanotubes. We have also shown that after I- sorption the nanotubes can be capped with latex particles. These capped structures could potentially serve as stable waste forms for the long lived anionic fission products. Preliminary evaluation data will be presented on the separation, sequestration (i.e., secondary waste leaching) and storage behavior of these structures.

Nanophase extractors for selective fission product sequestration

245th National Meeting (2013)

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