The Grout Treatment Facility (GTF) at Hanford, Washingtonwill process the low-level fraction of selected double-shelltank (DST) wastes into a cementitiouswaste form. This facility,which is operated by Westinghouse • Hanford Company (WHC), mixes liquid waste with cementitiousmaterials to produce a waste form that immobilizeshazardous constituentsthrough chemical • reactions and/or microencapsulation. Over 1,000,000 gal of Phosphate/Sulfate Waste were solidified in the first production campaign

more »

... th this facility. The next tank scheduled for treatment is I06-AN. After conducting laboratorystudies to select the grout formulation,part of the normal formulationverificationprocess is to conduct tests using the I/4-scale pilot facilitiesat the Pacific Northwest Laboratory (PNL). (a) The major objectives of these pilot-scaletests were to determine if the proposed grout formulation could be processed in the pilot-scaleequipment and to collect thermal information to help determine the best way to manage the grout hydration heat. Two molds were constructedto accomplishthese goals. The first mold was designed to produce a temperaturegradient in the grout, as it cured, in order to determine the effects of curing temperature on the final properties of the grout. The second mold was designed to simulate pouring grout in 2-ft lifts. The main grout production run filled the first mold and the first of four lifts in the second mold. Over 2000 gal of grout were processed during 3.5 hours of productiontime during the main pour. Three additional lift pours, each consistingof 350 gal, were conducted at l-week intervals to complete the second mold. The grout in the main run and the second and third lift pours was produced by mixing simulated I06-AN tank waste with dry-blend consisting of 14 wtr attapulgiteclay, 20 wtr cement, and 66 wtr class F fly ash at a mix ratio of 8.7 Ib per gal (Ib/gal). A dry-blend compositionof 11 wt% attapulgite,20.7 wtr cement, and 68.3 wtr class F fly ash with a mix ratio of 8.4 Ib/gal was used for the fourth lift. (a) PNL is operated for the U.S.