Application of SYNROC to high-level defense wastes

• Main Authors: Tewhey, J.D., Hoenig, C.L., Newkirk, H.W., Rozsa, R.B., Coles, D.G., Ryerson, F.J.
• Language: unknown
• Published: 2009
• Subjects: 12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES; HIGH-LEVEL RADIOACTIVE WASTES; LEACHING; RADIOACTIVE WASTE PROCESSING; SOLIDIFICATION; SYNROC PROCESS; CERAMICS; ELECTRON MICROPROBE ANALYSIS; HOT PRESSING; MINERALOGY; PEROVSKITE; SCANNING ELECTRON MICROSCOPY; SPINELS; TITANATES; UREA; VERY HIGH TEMPERATURE; X-RAY DIFFRACTION; ALKALINE EARTH METAL COMPOUNDS; ALUMINIUM COMPOUNDS; ALUMINIUM OXIDES; AMIDES; CALCIUM COMPOUNDS; CALCIUM OXIDES; CARBONIC ACID DERIVATIVES; CHALCOGENIDES; CHEMICAL ANALYSIS; COHERENT SCATTERING; DIFFRACTION; DISSOLUTION; ELECTRON MICROSCOPY; FABRICATION; MAGNESIUM COMPOUNDS; MAGNESIUM OXIDES; MANAGEMENT; MATERIALS; MATERIALS WORKING; MICROANALYSIS; MICROSCOPY; MINERALS; ORGANIC COMPOUNDS; ORGANIC NITROGEN COMPOUNDS; OXIDES; OXYGEN COMPOUNDS; PEROVSKITES; PHASE TRANSFORMATIONS; POLLUTANTS; PRESSING; PROCESSING; RADIOACTIVE MATERIALS; RADIOACTIVE WASTES; Carbonic acid
• Online Access: http://www.osti.gov/servlets/purl/6579627; https://www.osti.gov/biblio/6579627

The SYNROC method for immobilization of high-level nuclear reactor wastes is currently being applied to US defense wastes in tank storage at Savannah River, South Carolina. The minerals zirconolite, perovskite, and hollandite are used in SYNROC D formulations to immobilize fission products and actinides that comprise up to 10% of defense waste sludges and coexisting solutions. Additional phases in SYNROC D are nepheline, the host phase for sodium; and spinel, the host for excess aluminum and iron. Up to 70 wt % of calcined sludge can be incorporated with 30 wt % of SYNROC additives to produce a waste form consisting of 10% nepheline, 30% spinel, and approximately 20% each of the radioactive waste-bearing phases. Urea coprecipitation and spray drying/calcining methods have been used in the laboratory to produce homogeneous, reactive ceramic powders. Hot pressing and sintering at temperatures from 1000 to 1100/sup 0/C result in waste form products with greater than 97% of theoretical density. Hot isostatic pressing has recently been implemented as a processing alternative. Characterization of waste-form mineralogy has been done by means of XRD, SEM, and electron microprobe. Leaching of SYNROC D samples is currently being carried out. Assessment of radiation damage effects and physical properties of SYNROC D will commence in FY 81.