Vitrification is the primary disposition path for Low Activity Waste (LAW) at the Department of Energy (DOE) Hanford Site. A cementitious waste form is one of the alternatives being considered for the supplemental immobilization of the LAW that will not be treated by the primary vitrification facility. Washington River Protection Solutions (WRPS) has been directed to generate and collect data on cementitious or pozzolanic waste forms such as Cast Stone. This report documents work done to support supplemental immobilization efforts by performing testing on actual salt wastes immobilized in Cast Stone. The actual waste used in testing was a Savannah River Site (SRS) salt solution from Tank 50 H-area Tank Farm that was chemically adjusted with aluminum hydroxide, ammonium phosphate, and ammonium sulfate to represent Hanford salt waste. Radioactive Tc-99 and natural iodide-127 were also added to match previous simulant Tc-99 spike studies and to provide enough iodide for detection in the aqueous leachates. Using a chemically adjusted SRS salt waste avoided sampling, transportation and permitting issues, which would have been required for actual Hanford tank waste, while providing a readily available and representative sample for testing. Chemical adjustment of the SRS Tank 50 sample was verified by analysis showing targeted concentrations were achieved. Duplicate 2" x 4" 'baseline' monoliths were made using the adjusted Tank 50 salt solution and dry blend materials (premix) of ordinary portland cement (OPC), Class F fly ash (FA) and ground, granulated blast furnace slag (GGBFS) for a free water to premix ratio of 0.55. Three other sets of monoliths were made using various getters that included Potassium Metal Sulfide (KMS)-2 (K 2 MgSn 2 S 6), tin apatite (Sn 2 Ca 8 (PO 4) 6 Cl 2) and silver zeolite (Ag 84 Na 2 [(AlO 2) 86 (SiO 2) 106 ]•xH 2 O). The getters replaced mass from the premix, mass for mass, maintaining the effective premix ratio of 0.55. Monoliths were leach tested in reagent water using the Environmental Protection Agency (EPA) Method 1315 which is designed to provide mass transfer rates (release rates) of inorganic analytes contained in monolithic material under diffusion controlled release conditions as a function of leaching time. All initial species monolith concentrations used in the reported leachability index (LI) values are based on asbatched concentrations, i.e., no actual dissolution and characterization was performed on the monolithic cast stone matrix. As-batched species concentrations in the monoliths were based on analyzed adjusted Tank 50 supernate, previous analysis of premix components and calculated getter concentrations that are based on simple getter empirical formulas. Chemical adjustment of the SRS Tank 50 salt solution by the addition of Al, sulfate, phosphate and Tc-99 species, as well as natural iodide, met target levels as determined by chemical and radiochemical analysis. Monolith leach tests indicate no significant differences in the observed diffusivities (D obs) for these tes...
