The Idaho National Engineering and Environmental Laboratory (INEEL) is considering several optional processes for disposal of liquid sodium-bearing waste. During fiscal year 2002, immobilization-related research included of grout formulation development for sodium-bearing waste, absorption of the waste on silica gel, and off-gas system mercury collection and breakthrough using activated carbon. Experimental results indicate that sodium-bearing waste can be immobilized in grout at 70 weight percent and onto silica gel at 74 weight percent. Furthermore, a loading of 11 weight percent mercury in sulfur-impregnated activated carbon was achieved with 99.8% off-gas mercury removal efficiency.iv v EXECUTIVE SUMMARYThe Idaho National Engineering and Environmental Laboratory, specifically the Idaho Nuclear Technology and Engineering Center (INTEC) High-Level Waste Program, is to prepare the liquid sodium-bearing waste and calcined solids for eventual disposal. Several alternative treatment processes and disposal paths have been explored for these wastes. This report discusses research conducted on three process options: grouting of sodium-bearing waste following cesium removal, immobilization of sodium-bearing waste on silica gel following cesium removal, and use of activated carbon for mercury removal in the calciner or steam reformer off-gas system.During this fiscal year, the option of grouting sodium-bearing (SBW) waste was revisited to ensure the processes were still viable based on the latest flow sheets and projected SBW compositions. It was determined that the grout formulation for 70 weight percent continued to be satisfactory. New work was started for grouting of nitric acid such as that from the Liquid Effluent Treatment and Disposal Facility. Initial findings showed that 12 molar nitric acid can be grouted at 35 weight percent.Research continued on the absorption of SBW on silica gel. The process provides a simple method of solidifying the SBW for transportation or disposal. If the SBW is placed on silica gel at ambient temperatures, waste loadings of 74 weight percent can be achieved with a single addition. If the SBW and silica gel are heated more moisture and acid are driven off and waste loadings of 90 weight percent were found.If thermal methods are pursued for SBW treatment, it is proposed to use activated carbon to control mercury release in the off-gas systems. The activated carbon bed's mercury removal efficiency and breakthrough loading for the New Waste Calciner Facility were researched this fiscal year. It was found that a breakthrough loading of 11 weight percent and a removal efficiency of up to 99.8% were achievable. vi vii NOMENCLATURE Alkaline GroutA grout formulation where the waste is rendered basic (pH > 12) and mixed with a 9:1 blend of blast furnace slag and portland cement.

The Idaho National Engineering and Environmental Laboratory (INEEL) is considering several optional processes for disposal of liquid sodium-bearing waste. During fiscal year 2003, alternatives were evaluated for grout formulation development and associated mixing for the Sodium-Bearing Waste cesium ion exchange process. The neutralization agents calcium or sodium hydroxide and the solidification agents Portland cement, with or without blast furnace slag were evaluated. A desired uniform formulation was pursued to develop a grout waste form without any bleed liquid and solidify within a reasonable period of about twenty-eight days. This testing evaluates the out-of-drum alternative of mixing the effluent with solidification agents prior to being poured into drums versus the in-drum alternative of mixing them all together after being poured into the drums. Experimental results indicate that sodium-bearing waste can be immobilized in grout using the Autocon continuous mixer within the range of 66 to 72 weight percent. Furthermore, a loading of 30 weight percent NWCF scrubber simulant also produced an acceptable grout waste form. EXECUTIVE SUMMARYThe Idaho National Engineering and Environmental Laboratory, specifically the Idaho Nuclear Technology and Engineering Center (INTEC) High-Level Waste Program, is to prepare the liquid sodium-bearing waste for eventual disposal. Several alternative treatment processes and disposal paths have been explored for these wastes. This report discusses research conducted on one of these process options, which is grouting of sodium-bearing waste following cesium removal.The out-of-drum grout mixer testing has demonstrated that the Autocon continuous mixer is capable of producing an acceptable grout waste form from the WM-180, WM-189, and NWCF scrub simulants. The best grout formulations were made by combining the solids (calcium hydroxide and Portland cement and/or blast furnace slag) then mixing the combined solids with the liquid SBW to both neutralize and solidify the acidic simulant. The Autocon mixer was sized to allow processing of grout batch sizes in the range of one to fifty-five gallons.

In this report, the mechanism and methods of fixation of acidic waste effluents in grout form are explored. From the variations in the pH as a function of total solids addition to acidic waste effluent solutions, the stages of gellation, liquefaction, slurry formation and grout development are quantitatively revealed. Experimental results indicate the completion of these reaction steps to be significant for elimination of bleed liquid and for setting of the grout to a dimensionally stable and hardened solid within a reasonable period of about twenty eight days that is often observed in the cement and concrete industry. The reactions also suggest increases in the waste loading in the direction of decreasing acid molarity. Consequently, 1.0 molar SBW-180 waste is contained in higher quantity than the 2.8 molar SBW-189, given the same grout formulation for both effluents. The variations in the formulations involving components of slag, cement, waste and neutralizing agent are represented in the form of a ternary formulation map. The map in turn graphically reveals the relations among the various formulations and grout properties, and is useful in predicting the potential directions of waste loading in grouts with suitable properties such as slurry viscosity, Vicat hardness, and mechanical strength. A uniform formulation for the fixation of both SBW-180 and SBW-189 has emerged from the development of the formulation map. The boundaries for the processing regime on this map are 100 wt% cement to 50 wt% cement / 50 wt% slag, with waste loadings ranging from 55 wt% to 68 wt%. Within these compositional bounds all the three waste streams SBW-180, SBW-189 and Scrub solution are amenable to solidification. A large cost advantage is envisaged to stem from savings in labor, processing time, and processing methodology by adopting a uniform formulation concept for fixation of compositionally diverse waste streams. The experimental efforts contained in this report constitute the first attempt at developing a uniform methodology. iv v EXECUTIVE SUMMARYThe sodium bearing waste (SBW) is an acidic liquid solution of several nitrate components. In view of its acidic nature, one of the aims of the Idaho Completion Project is to have it removed from the storage tanks at Idaho Nuclear Technology and Engineering Center (INTEC), and have it transformed into a disposable solid. Two types of disposable solids are under consideration: grout and silica gel. Commercially available Portland cement, slag and silica gel have been used in the present project for solidifying the three types of waste streams SBW-180, SBW-189 and NWCF Scrub solutions. A large part of this report concentrates on the investigation of the waste fixation in a grout matrix, while preliminary results of waste adsorption onto silica gel are also presented. Neutralizing the waste solutions to a weaker acid is considered important from the point of inhibiting the corrosive effects on cesium ion exchange silico-titanate resins, and for enhancing the retention of wast...