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Detailed Program
Paper Number : GL-O05
Time Frame : 11:58~12:10
Presentation Date : Thurse day, 27, November
Session Name : Glass & Optp-Electonic Materials
Session Chair 1# : Yong Gyu Choi
Session Chair 2# : Atsunobu Masuno
Accumulation of Lanthanide Ions inside the Crystalline Phases in Vitustie Glass-Ceramics Wasteforms
Miae KIM
POSTECH
Pyro-processing is being investigated to recover radioactive uranium and trans-uranium elements from the spent fuels of pressurized water reactors [1-2]. We fabricated glass-ceramics containing sodium cerium(neodymium) phosphate [Na3Ln(PO4)2] crystals as wasteforms for immobilization of lanthanide ion wastes produced by pyro-processing. We investigated the distributions and local environment of rare-earth ions in the glass-ceramics and evaluated the chemical durability of glass-ceramics wasteforms.
The nominal composition (mol %) of the glass prepared was 47SiO2 - 28Na2O - 11B2O3 - 8Li2O - 2CeO2 - 1.6Nd2O3 - 5.4P2O5. As-prepared glasses were heat-treated at 500-800¡ÆC for 3h to precipitate crystals. The crystals formed was identified as vitusite [Na3Ln(PO4)2] based on peaks in the X-ray diffraction (XRD) patterns. Most of the radionuclides appear to reside in the crystalline phases and it was proven by energy dispersive spectroscopy (EDS). In addition, local structure surrounding lanthanide ions were also analyzed by extended X-ray absorption fine structure (EXAFS). All results suggest that glass-ceramics containing sodium phosphate crystals are good candidate wasteforms for immobilization of lanthanide wastes generated by pyro-processing.

Figure 1 SEM image of one vitusite crystal and elemental mappings of Si, P, Ce and Nd obtained from EDS. Brightness increases with concentration.

References:
[1] T. Inque, L. Koch, Nucl. Eng. Technol., 40 (2008) 183
[2] H.S. Lee, J.M. Hur, J.G. Kim, D.H. Ahn, Y.Z. Cho and S.Y Paek, Energy Procedia, 7(2011) p. 391-395
Acknowledgements : This research was supported by Priority Research Center (2009-0094036) and BK21+ Program through the National Research Foundation (NRF) of Korea funded by the Ministry of Education.