Structure and Properties of Iron Phosphate Based-Glasses for Immobilization of Demonstration Ferrocyanide Sludge

The immobilization of barium strontium sulfate and potassium cesium nickel ferrocyanide sludge produced during the treatment of radioactive water at the Fukushima Daiichi nuclear power plant was investigated employing multi-component iron phosphate glass. The study examined glass formation, thermal properties, melt viscosity, and water durability as functions of demonstration sludge concentration. The presence of crystalline and non-crystalline phases was determined via X-ray diffraction. Microstructures and composition distributions of the glass samples were evaluated via scanning electron microscopy (SEM) and field-emission SEM coupled with energy dispersive spectroscopy. Water durability was evaluated using materials characterization center (MCC)-2 static leaching tests at high temperatures. The melt viscosity was evaluated employing rotation cylinder method within the temperature range 1000-1200 ° C. Differential thermal analysis was performed to evaluate the characteristic temperatures and thermal stability with respect to crystallization. The glass network structure of the PO 4 tetrahedra, evaluated via Raman spectroscopy, was correlated with the thermal properties, melt viscosity, and water durability. Furthermore, the applicability of iron phosphate glasses for sludge immobilization is discussed as a case study of waste treatment arising from accidents for sustainable nuclear power generation.