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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 will develop 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. Characterization of the material will be accomplished through probing the 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 performance 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.
Highlights of Accomplishments:
1) Multiple samples of hydroxyapatite prepared some with surrogates (varying Ca/Zn weight ratios) and some pure samples which have then been analyzed with IR, TGA/DSC and XRD techniques.
2) Fluorapatite samples synthesized using the reflux method and analyzed with SEM, XPS, XRD and single point IR.
3) Experiments conducted with natural fluorapatite and hydroxyl apatite using the precipitation method to determine if procedure to synthesize fluorapatite differs based on samples used. XRD was used to analyze the synthesized samples.
4) Synthesized yttrium and cesium containing FAP samples using the same method that was used for Strontium (explained in last report) and obtained XRD, SEM and DSC data for samples.
Calcium phosphate; Fluorides; Fluorination; Hydroxyapatite; Phosphate minerals; Radioactive wastes — Storage; Separation (Technology); Strontium; Zinc; Zirconium compounds
Radioactive wastes--Storage; Separation (Technology); Zirconium compounds
Chemistry | Oil, Gas, and Energy | Physical Chemistry
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Lindle, D. W.,
Evaluation of Fluorapatite as a Waste-Form Material: First Quarter Report (2004-05), October 1 - December 31, 2004.
Available at: https://digitalscholarship.unlv.edu/hrc_trp_separations/56