Crystal Chemistry of Immobilization of tetravalent Ce and Se in ceramic matrix of sodium zirconium phosphates

The safe and effective management of radioactive waste has been given utmost importance from the very inception of nuclear industry in India and it covers the entire range of activities from handling, treatment, conditioning, transport, storage and finally disposal. Radioactive waste is generated at various stages of the nuclear fuel cycle, which includes the mining and milling of uranium ore, fuel fabrication, reactor operation and spent fuel reprocessing Sodium zirconium phosphate (here after NZP) is a typical host material capable of converting the intermediate level waste resulting from light water reactor (LWR) fuel reprocessing in to a single-phase material with good stability, high integrity and long durability. The crystal chemistry of NaZr1.9Ce0.1P3O12 and NaZr1.9Se0.1P3O12 phases has been investigated using general structure analysis system programming. The Se/CeNZP phases crystallize in the space group R-3c and Z = 6. Powder diffraction data have been subjected to rietveld refinement to arrive at a satisfactory structural convergence of R-factors. The PO4 stretching and bending vibrations in the infrared (IR) region have been assigned. SEM and EDAX analysis provide evidence of Ce and Se in the matrix.