DEVELOPMENT AND DEMONSTRATION OF A SYSTEM FOR VITRIFYING HIGH LEVEL RADIOACTIVE WASTE IN HIGH SILICA GLASS

Improved media are needed to package high level radioactive waste for burial. Preliminary testing of a high silica glass process suggested that the requirement could be satisfied by fixing the waste in a high silica core surrounded by a waste-free high silica clad. This dissertation reports the development of the technology to execute the process remotely and the demonstration of the remote process, using simulated high level waste separated into sludge and clarified liquid phases. The radioactivity concentration of the liquid and the composition of the sludge were comparable to the waste at the Savannah River Plant of the U.S. Department of Energy.;The technology developed for remote ion exchange and vitrification is shown to be satisfactory; some improvements are suggested. A short-term test demonstrated the leach rate from the waste form to be less than 10;An ion exchange medium consisting of porous glass matrix glass powder was used in batch mode to achieve liquid phase decontamination factors of approximately 39 for Sr-90, 7 for Co-60 and 5 for Cs-137. Following ion exchange, the decontaminated liquid was decanted; the sludge was added to the spent medium; the stirred mixture was vacuum dried at elevated temperature, and the resultant powder was transferred into a non-radioactive high silica glass tube. Programmed heating and pressure reduction calcined non-oxide components, collapsed the particles of porous glass to physically trap material in the pores, agglomerated the collapsed particles to trap inter-granular sludge particles, and collapsed the clad tube about the core.