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Title: Synthesis of garnet/perovskite-based ceramic for the immobilization of Pu-residue wastes

Abstract

The use of garnet/perovskite-based ceramic, with formula type (Y, Gd,{hor{underscore}ellipsis}){sub 3}(Al,Ga,{hor{underscore}ellipsis}){sub 5}O{sub 12}/(Y,Gd,{hor{underscore}ellipsis})(Al,Ga,{hor{underscore}ellipsis})O{sub 3}, was tested for immobilizing plutonium residue wastes. Pu residue wastes originate from nuclear weapons production and can contain more than 50% of impurities including such elements as Am, Al, Mg, Ga, Fe, K, La, Na, Mo, Nd, Si, Ta, Ce, Ba, B, W, Zn, Zr, C and Cl. While for some of these residues, direct conversion to typical glass or ceramic forms may be difficult, ceramic forms based on durable actinide host-phases are preferred for Pu, Am and other actinides immobilization. Garnet/perovskite crystalline host-phases are chemically and mechanically durable and desirable for the incorporation of Pu and most of the impurity elements in the Pu residue wastes in the lattices of host-phases in the form of solid solutions. Experiments on the synthesis of garnet/perovskite ceramic samples were carried out using melting in air at temperatures from 1,300 C (for samples doped with 10 wt.% Pu residue waste simulant) to 2,000 C (for samples doped with 10 wt.% Ce or U). Samples were studied by XRD, SEM and cathodoluminescence techniques. It was found that the garnet phase can incorporate up to 6 wt.% Ce and up tomore » 4.0--5.5 wt.% U, which is correlated with the increase of Ga content and decrease of Al content in the melt. In one of the features of the melt, the perovskite phase formation substitutes for the formation of garnet. The capacity of the perovskite lattice to accommodate Ce and U is higher than the capacity of garnet, reaching about 8 and 7 wt.%, respectively. It was shown that cathodoluminescence can be effectively used to determine the valence state of Ce and U, an important step to optimize the starting precursor preparation. In case of U{sup 4+} in the melt, the charge-compensating elements (Sn{sup 2+}, Ca{sup 2+}{hor{underscore}ellipsis}) are needed to successfully incorporate U in the garnet lattice.« less

Authors:
; ; ; ; ;
Publication Date:
Research Org.:
V.G. Khlopin Radium Inst., St. Petersburg (RU)
OSTI Identifier:
20015741
Resource Type:
Conference
Resource Relation:
Conference: 1998 Materials Research Society Fall Meeting, Boston, MA (US), 11/30/1998--12/04/1998; Other Information: Single article reprints are available from University Microfilms Inc., 300 North Zeeb Road, Ann Arbor, Michigan 48106; PBD: 1999; Related Information: In: Scientific basis for nuclear waste management XXII. Materials Research Society symposium proceedings: Volume 556, by Wronkiewicz, D.J.; Lee, J.H. [eds.], 1355 pages.
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 12 MANAGEMENT OF RADIOACTIVE WASTES, AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES; PLUTONIUM; WASTE FORMS; GARNETS; PEROVSKITE; MATERIALS TESTING; SYNTHESIS; PHASE STUDIES; URANIUM; CERIUM; CATHODOLUMINESCENCE

Citation Formats

Burakov, B E, Anderson, E B, Knecht, D A, Zamoryanskaya, M A, Strykanova, E E, and Yagovkina, M A. Synthesis of garnet/perovskite-based ceramic for the immobilization of Pu-residue wastes. United States: N. p., 1999. Web.
Burakov, B E, Anderson, E B, Knecht, D A, Zamoryanskaya, M A, Strykanova, E E, & Yagovkina, M A. Synthesis of garnet/perovskite-based ceramic for the immobilization of Pu-residue wastes. United States.
Burakov, B E, Anderson, E B, Knecht, D A, Zamoryanskaya, M A, Strykanova, E E, and Yagovkina, M A. Thu . "Synthesis of garnet/perovskite-based ceramic for the immobilization of Pu-residue wastes". United States.
@article{osti_20015741,
title = {Synthesis of garnet/perovskite-based ceramic for the immobilization of Pu-residue wastes},
author = {Burakov, B E and Anderson, E B and Knecht, D A and Zamoryanskaya, M A and Strykanova, E E and Yagovkina, M A},
abstractNote = {The use of garnet/perovskite-based ceramic, with formula type (Y, Gd,{hor{underscore}ellipsis}){sub 3}(Al,Ga,{hor{underscore}ellipsis}){sub 5}O{sub 12}/(Y,Gd,{hor{underscore}ellipsis})(Al,Ga,{hor{underscore}ellipsis})O{sub 3}, was tested for immobilizing plutonium residue wastes. Pu residue wastes originate from nuclear weapons production and can contain more than 50% of impurities including such elements as Am, Al, Mg, Ga, Fe, K, La, Na, Mo, Nd, Si, Ta, Ce, Ba, B, W, Zn, Zr, C and Cl. While for some of these residues, direct conversion to typical glass or ceramic forms may be difficult, ceramic forms based on durable actinide host-phases are preferred for Pu, Am and other actinides immobilization. Garnet/perovskite crystalline host-phases are chemically and mechanically durable and desirable for the incorporation of Pu and most of the impurity elements in the Pu residue wastes in the lattices of host-phases in the form of solid solutions. Experiments on the synthesis of garnet/perovskite ceramic samples were carried out using melting in air at temperatures from 1,300 C (for samples doped with 10 wt.% Pu residue waste simulant) to 2,000 C (for samples doped with 10 wt.% Ce or U). Samples were studied by XRD, SEM and cathodoluminescence techniques. It was found that the garnet phase can incorporate up to 6 wt.% Ce and up to 4.0--5.5 wt.% U, which is correlated with the increase of Ga content and decrease of Al content in the melt. In one of the features of the melt, the perovskite phase formation substitutes for the formation of garnet. The capacity of the perovskite lattice to accommodate Ce and U is higher than the capacity of garnet, reaching about 8 and 7 wt.%, respectively. It was shown that cathodoluminescence can be effectively used to determine the valence state of Ce and U, an important step to optimize the starting precursor preparation. In case of U{sup 4+} in the melt, the charge-compensating elements (Sn{sup 2+}, Ca{sup 2+}{hor{underscore}ellipsis}) are needed to successfully incorporate U in the garnet lattice.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {1999},
month = {7}
}

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