Document Type

Grant

Publication Date

2004

First page number:

1

Last page number:

14

Abstract

Fluorapatite, fluorinated calcium phosphate, has been identified as a potential matrix for the entombment of the zirconium fluoride fission product waste stream from the proposed FLEX process. If the efficacy of fluorapatite based waste-storage can be demonstrated, then new and potentially more-efficient options for handling and separating high-level wastes, based on fluoride-salt extraction, will become feasible. This proposal is for renewal of the UNLV portion of a dual-path research project to develop a process to fabricate a synthetic fluorapatite waste form for the ZrF4, FP waste stream, characterize the waste form, examine its performance under environmental conditions, and correlate the behavior of the waste form with natural analogs. At UNLV, characterization of the material will be accomplished by probing molecular-scale electronic and geometric structure of the materials in order to relate them to macroscopic properties, with the goal of developing techniques to evaluate and predict the performances of different waste-form materials. Time and funding permitting, other waste forms for the zirconium fluoride, fission product salt waste stream will be examined and benchmarked against the fluorapatite matrix baseline.

The work in the third year of the project will continue to progress along two parallel paths: Fabrication and Natural-Analog Characterization. The Fabrication path, led by the KRI team, will evaluate various techniques for the fabrication of synthetic fluorapatite, will synthesize fluorapatite, and will begin the examination of waste loading and fabrication process factors on the synthetic fluorapatite. The Characterization path, led by the UNLV team, has been performing baseline spectroscopic studies of natural and pristine (no artificially added impurities) apatite materials and is beginning to apply the same techniques to more-complex fluorapatite-based waste forms made by the KRI Fabrication team. The ultimate goal is to use these techniques to achieve a molecular-level understanding of natural fluorapatite and other fluorine-bearing phases as natural analogs for waste-form materials. These techniques will also be used to examine changes in surface chemistry caused by environmental degradation.

Keywords

Calcium phosphate; Fluorides; Fluorination; Radioactive wastes — Storage; Separation (Technology); Zirconium compounds

Controlled Subject

Radioactive wastes--Storage; Separation (Technology); Zirconium compounds

Disciplines

Chemistry | Oil, Gas, and Energy | Physical Chemistry

File Format

pdf

File Size

1100 KB

Language

English

Rights

COPYRIGHT UNDETERMINED. For more information about this rights statement, please visit http://rightsstatements.org/vocab/UND/1.0/

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