Plutonium and neptunium incorporation in zirconolite

Conference · Tue Dec 30 23:00:00 EST 1997

OSTI ID:572075

Begg, B D; Vance, E R; Day, R A; Hambley, M ^[1]; Conradson, S D ^[2]

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1. ANSTO, Menai, New South Wales (Australia). Materials Div.
2. Los Alamos National Lab., NM (United States)

The incorporation of Pu and Np in zirconolite (CaZrTi{sub 2}O{sub 7}) has been investigated over a range of redox conditions. Zirconolite formulations designed to favor either trivalent or tetravalent Pu and Np were prepared by limiting the amount of charge compensating additives available to maintain electroneutrality. From near-edge X-ray absorption spectroscopy the Pu valence state was found to vary with the processing atmosphere, from completely tetravalent when fired in air, and located on either the Ca or Zr sites, to trivalent, when substituted on the Ca site after annealing in 3.5% H{sub 2}/N{sub 2}. Np was predominantly tetravalent over the range of redox conditions examined and was readily incorporated on either of zirconolite`s Ca or Zr sites. The charge compensation mechanisms at work in different zirconolites are also discussed.

• OSTI ID: 572075
• Report Number(s): CONF-961202--
• Country of Publication: United States
• Language: English

Related Subjects

05 NUCLEAR FUELS
CRYSTAL STRUCTURE
ION EXCHANGE
NEPTUNIUM
PHASE STUDIES
PLUTONIUM
SORPTIVE PROPERTIES
SYNROC PROCESS
WASTE FORMS
ZIRCONOLITE