Optimization of immobilization of strontium and uranium by the solid matrix
One of the basic physical parameters which defines: (1) the capacity of the solid matrix for the incorporation (sorption) of the impurity and (2) the stability of the solid matrix-impurity system, is the ion-ion interaction potential, representing the main term of the cohesive energy. Using this parameter determined in the frame of the pseudopotential theory and pseudoatomic approximation the authors have investigated the systems HAP-Sr and HAP-UO{sub 2}. In analysis, the hydroxyapatite (HAP, Ca{sub 10}(PO{sub 4}){sub 6}(OH){sub 2}) was selected as a model solid matrix since insoluble phosphates, phosphate ceramic and apatite-like materials are candidates for the immobilization of radionuclides. The substitution of calcium atoms by different impurities in HAP can be presented by the formula: Ca{sub 10{minus}x}M{sub x}(PO{sub 4}){sub 6}(OH){sub 2}, where 0 {le} x {le}10 and M = Sr{sup 2+}, UO{sub 2}{sup 2+}. It has been shown that (1) Sr can be safely immobilized by HAP, natural apatites and phosphate rocks in the whole range of its concentrations, and (2) that HAP is not an appropriate solid-matrix for immobilization of UO{sub 2}{sup 2+} because its incorporation in the low concentration results in a decrease of the matrix stability, stimulating formation of the inhomogeneous structure containing isolated clusters of the UO{sub 2}-apatite solid phase.
- Research Organization:
- VINCA Inst. of Nuclear Sciences, Belgrade (YU)
- OSTI ID:
- 20015752
- 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
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