Preparation and Chemical Stability of Sr0.5Zr2(PO4)3-(Ce,Sm)PO4 Multiphase Ceramic Nuclear Waste Forms
In order to simultaneously immobilize the simulated radionuclides Sr,Ce,and Sm in high-level radioactive wastes,Sr0.5Zr2(PO4)3-(Ce,Sm)PO4 multiphase phosphate ceramic waste forms were successfully prepared in this paper by a one-step microwave sintering process.The phase composition,microstructures and density were investigated by XRD,Raman,SEM-EDS and densitometry,respectively.Meanwhile,the chemical stability was evaluated using the PCT method.The results show good compatibility between the Sr0.5Zr2(PO4)3 phase and the(Ce,Sm)PO4 monazite phase,with no mutual reactions occurring between the two phases.The prepared multiphase ceramic waste forms exhibit small grain size and a relative density exceeding 96％,with no significant impact on microstructure or density observed with changes in the Sm/Ce ratio.PCT test results show that the elemental normalized leaching rates of Sr,Ce and Sm are all low-level,demonstrating superior chemical stability compared to single-phase phosphate ceramic forms.
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