The Effect of Glass Composition Containing RE Oxide Waste Glass on Liquidus Temperature
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The Effect of Glass Composition Containing RE Oxide Waste Glass on Liquidus Temperature S. Mohd Fadzil1,2 and P. Hrma1,3 1 Division of Advanced Nuclear Engineering, Pohang University of Science and Technology, 790784 Pohang, South Korea 2 School of Applied Physics, Faculty of Science and Technology, The National University of Malaysia, 43650 Bandar Baru Bangi, Selangor, Malaysia 3 Pacific Northwest National Laboratory, P.O. Box 999, Richland, Washington, The United States ABSTRACT The liquidus temperature (TL) of rare earth (RE) was determined for alumino-borosilicate glasses for treating americium and curium that have been studied previously. Their work covers a wide range of glass composition with various crystalline phases as primary phase. Present work is aimed at understanding the effect of glass composition on TL for waste glasses designed for vitrifying RE oxides wastes. In a sufficiently narrow composition region, this effect can be represented by a first-order model fitted measured TL versus composition data. Test glasses were formulated by varying of component fractions one-at-a-time. The glasses contained SiO2, B2O3, and Al2O3 as glass formers and Nd2O3 with CeO2 as simulated RE waste. Twenty glasses were made to investigate crystallization as a function of temperature and glass composition. The primary crystalline phase was Ce-borosilicate (Ce3BSi2O10), secondary phases were Alcontaining crystals (Al2O3 and Al10Si2O19), and crystalline CeO2. A first-order model was fitted to crystal fraction versus glass composition data. Generally, SiO2 and B2O3 tend to suppress crystallization, Al2O3 has little effect, and, as expected, RE components (Nd2O3 and CeO2) promote it. The correlation coefficient, R2, was 0.89 for the primary crystalline phase TL as a linear function of composition. INTRODUCTION Rare earth alumino-borosilicate (LABS) glasses have been developed for treating Am and Cm in the Savannah River Site’s (SRS) F-Canyon [1,2]. Based on excellent waste loading of these glasses for over 40 mass%, a similar glass composition was adapted to accommodate the lanthanide oxides CeO2 and Nd2O3. These lanthanides were representative for mixed lanthanides waste stream that will be generated from reprocessing of spent nuclear fuel using pyroprocess technology. This technology has been tested in pilot scale study since 2012 in Korean Atomic Energy Research Institute (KAERI) [3]. We formulated and produced 20 glass compositions by modifying the baseline glass composition of 19.73 SiO2 – 7.97 B2O3 – 19.30 Al2O3 – 20.24 CeO2 – 32.76 Nd2O3 in mass%. The waste loading ranged from 49.5 to 56.5 mass%. The components varied one at a time while keeping remaining components in equal proportions. A similar approach has been used before to study the component effects on spinel crystals [4]. In this paper, we discussed the effects of composition of these glasses on crystal fractions and the liquidus temperature (TL).
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