Leaching characteristics of glassy waste forms containing two different incineration ashes

Several glassy waste forms are fabricated from two different incineration a shes, respectively, at different mixing ratios of ashes to base glass. Inci neration ashes used in the experiments are hazardous waste (HW) incineratio n ash from a paint factory and simulated radioactive waste (RW) incineratio n ash from a nuclear power plant. To assess the chemical durability, which is known to be the most important factor in the waste form integrity, of gl assy waste forms, long-term leaching tests such as MCC-4S (for HW glassy wa ste form) and ISO (for RW glassy waste form) methods were conducted at 70 d egrees C for over 500 days. By observing the initial leach ratio of glass c omponents, it was found that silicon and calcium uniformly leached out afte r the early leaching of sodium and boron. For sodium and boron, diffusion i s a dominant leaching mechanism, while dissolution associated with diffusio n affects the leaching of silicon and calcium. Like glass constituents, lea ching characteristics of hazardous metals and surrogate nuclides are also d ependent upon solubility. (C) 2000 Elsevier Science Ltd. All rights reserve d.