Self-Propagating High-Temperature Synthesis of Simulated ⁹⁰SrO-Contained Radioactive Graphite in N₂ Atmosphere

Abstract:

In order to evaluate the performance of the self-propagating high-temperature synthesis (SHS) to treat ⁹⁰SrO-contained radioactive graphite in N₂ atmosphere, waste forms were prepared with the self-developed SHS reactor according to the waste forms formulation designed with a solid-soluted content of 010 wt% (calibrated in mass, hereinafter the same). The waste forms were made with the exothermic reaction (3C + 4Al + 3TiO₂ = 2Al₂O₃ + 3TiC + Q), where, ⁸⁸SrO (a stable Sr isotope)-containing ⁸⁸SrO was used to simulate ⁹⁰SrO. And the raw materials for the waste forms were the powdery materials of graphite (C), aluminum (Al) and titanium dioxide (TiO₂). Then, X-ray diffractometer (XRD) and scanning electron microscope (SEM) were used to test and analyze the phase composition and morphology of the prepared waste forms. According to the results in dealing with the treatment with the given exothermic reaction of the ⁹⁰SrOcontaining radioactive graphite in N₂ atmosphere, the SrO solid solubility could be up to 8 wt%. Besides, with a SrO content of 0~2 wt%, the major composition of the waste forms was including: alumina (Al₂O₃) in diamond scheme, titanium carbide (TiC) in cubic phase, graphite (C), anatase titanium dioxide (TiO₂) and aluminum nitride (AlN) in cubic phase. Comparatively, with a SrO content of 3~8 wt%%, the major composition of the waste forms was including: alumina (Al₂O₃) in diamond scheme, titanium carbide (TiC) in cubic phase, graphite (C), anatase titanium dioxide (TiO₂), aluminum nitride (AlN) in cubic phase and rhomboid aluminum titanate (Al₂TiO₅). Furthermore, diffractive peaks of unidentified phase occurred at 2θ = 7.7°, 15.6°, 19.8° and 24.1° position, whose intensities were increased with the increasing additional SrO content. The grain sizes of the prepared waste forms are mainly within 515μm, majorly exist in pieces.

• Periodical: Applied Mechanics and Materials (Volume 525)
• Pages: 45-52
• DOI: https://doi.org/10.4028/www.scientific.net/AMM.525.45
• Online since: February 2014
• Authors: Xi Rui Lu, Si Jin Su, Meng Jun Chen
• Keywords: ⁹⁰SrO, Radioactive Graphite, SHS, Solidsolubility, Waste Forms

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