Apatite structure provides a great potential for incorporating long-lived radioactive fission products from nuclear waste streams. Because of its chemical durability, structural and compositional flexibility, and ability to incorporate anions in the structural channel, apatite waste forms can reduce radionuclides reseal rate and minimize the waste volume. This abstract focuses on the development of iodine-apatite waste forms (i.e., Pb-V-I apatite) and its dissolution studies under various solution conditions.Standard leach tests are employed, following the standard test protocols, which use distilled water as the leachate. Leaching studies were performed on sintered pellets and powder samples of selected apatite waste forms (before and after ionizing irradiation) at different leach times following subsequent sampling. Dissolution rate and concentration are analyzed by ICP-MS spectroscopy. The results show that the dissolution rate is comparable with the natural apatite samples. In addition, the apparent activation energy of the dissolution is derived from experiments at different temperatures.  The effect of the pH on the dissolution rate is investigated by experiments of samples carried out at different pH conditions. The results provide improved understanding of the mechanisms and kinetics of dissolutions of different apatite waste forms. This understanding can provide important insights for apatite waste design.

Apatite waste froms for radionuclide incorporation and long term performance

247th National Meeting (2014)

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