SummaryThe Hanford Site in southeast Washington State has 56 million gallons of radioactive and chemically hazardous wastes stored in 177 underground tanks (DOE 2010). The U.S. Department of Energy Office of River Protection, through its contractors, is constructing the Hanford Tank Waste Treatment and Immobilization Plant (WTP) to convert the radioactive and hazardous wastes into stable glass waste forms for disposal. Within the WTP, the pretreatment facility will receive the retrieved waste from the tank farms and separate it into two treated process streams. These waste streams will be vitrified, and the resulting waste canisters will be sent to offsite (high-level waste) and onsite (immobilized low-activity waste) repositories. As part of the pretreatment and immobilized low-activity waste processing, liquid secondary wastes will be generated that will be transferred to the Effluent Treatment Facility on the Hanford Site for further treatment. These liquid secondary wastes will be converted to stable solid waste forms that will be disposed of in the Integrated Disposal Facility.To support the selection of a waste form for the liquid secondary wastes from the WTP, Washington River Protection Solutions has initiated secondary waste form testing work at Pacific Northwest National Laboratory. In anticipation of a down-selection process for a waste form for the Solidification Treatment Unit to be added to the Effluent Treatment Facility, Pacific Northwest National Laboratory is developing data packages to support that down-selection. The objective of the data packages is to identify, evaluate, and summarize the existing information on the four waste forms being considered for stabilizing and solidifying the liquid secondary wastes. This data package developed for the DuraLith waste form includes information available in the open literature and from data obtained from testing currently underway.DuraLith is an alkali-activated geopolymer waste form developed by the Vitreous State Laboratory at The Catholic University of America (VSL-CUA) for encapsulating liquid radioactive waste. A DuraLith waste form developed for treating Hanford secondary waste liquids is prepared by alkali-activation of a mixture of ground blast furnace slag and metakaolin with sand used as a filler material.Based on optimization tests, solid waste loading of ~7.5% and ~14.7% has been achieved using the Hanford secondary waste S1 and S4 simulants, respectively. The Na loading in both cases is equivalent to ~6 M. Some of the critical parameters for the DuraLith process include hydrogen generation and heat evolution during activator solution preparation using the waste simulant, heat evolution during and after mixing the activator solution with the dry ingredients, and a working window of ~20 minutes to complete the pouring of the DuraLith mixture into molds. Results of the most recent testing indicated that the working window can be extended to ~30 minutes if 75 wt% of the binder components, namely, blast furnace slag and metakaolin are replace...
