A major challenge facing nuclear energy is disposal of nuclear waste. In this regard, technetium is particularly problematic due to the stability and environmental mobility of TcO4-. One route to identify potential waste forms is to find durable, naturally occurring minerals that could incorporate technetium. The ionic radius of Tc4+ is similar to that of Ti4+ and Fe3+; therefore, iron and titanium oxides are attractive targets for technetium waste forms. Titanium oxides are extremely durable, but controlling the oxidation state of Tc in titanium oxides is challenging. Like titanium oxides, many iron oxides are highly durable, notably hematite, goethite and spinel ferrites (MFe2O4). As a first step in investigating iron oxides as technetium waste forms, the results from incorporation of Tc4+ into MFe2O4 will be presented, where M is Mg, Mn, Fe, Co, or Ni. The mineral phases were characterized by X-ray diffraction. The local environment of Tc was determined X-ray absorption fine structure spectroscopy to determine the Tc oxidation state and whether or not Tc was incorporated into the spinel lattice. While incorporation of technetium into crystal lattice of these oxides is straightforward, the behavior of technetium is surprising.

Incorporation of technetium into spinel ferrites

247th National Meeting (2014)

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