Neptunium incorporation in the torbernite/meta-torbernite [Cu(UO2)2(PO4)2�nH2O] system has been investigated under both hydrothermal and slow diffusion conditions (at room temperature and 90�C) to study the role played by synthetic conditions on neptunium uptake by uranyl phases. The effects of concentration and length of synthesis have also been investigated. Hydrothermally prepared samples showed much greater neptunium uptake than either set of diffusion reactions and displayed higher incorporation levels at higher concentrations. The neptunium in these samples was determined to be neptunium(VI) although the starting material contained only neptunium(V) and no oxidizing species were present. Decreased levels of neptunium uptake were observed in the slow diffusion samples as the length of the reaction was increased. More neptunium was incorporated in room temperature samples than in high temperature reactions; however, low incorporation levels prevented the determination of the oxidation state of neptunium in either of the slow diffusion reactions.

Synthetic influences on neptunium incorporation in naturally occurring copper uranyl phosphates

245th National Meeting (2013)

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