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Plans are underway at the Hanford Site near Richland, Washington, to convert the low-level fraction of radioactive liquid wastes to a grout form for permanent disposal. Grout is a mixture of liquid waste and grout formers, including portland cement, fly ash, and clays. In the plan, the grout slurry is pumped to subsurface concrete vaults on the Hanford Site, where the grout will solidify into large monoliths, thereby immobilizing the waste. A similar disposal concept is being planned at the Savannah River Laboratory site. The underground disposal of grout was conducted at Oak Ridge National Laboratory between 1966 and 1984 (Dole 1985). Design and construction of grout processing and disposal facilities are underway. The Transportable Grout Facility (TGF), operated by Rockwell Hanford Operations (Rockwell) for the Department of Energy (DOE), is scheduled to yrout Phosphate/Sulfate N Reactor Operations Waste (PSW) in FY 1988. Phosphate/ Sulfate Waste is a blend of two low-level waste streams yenerated at Hanford's N Reactor. (The N Reactor produces special nuclear materials, and its byproduct steam is used to generate electricity.) Other wastes are scheduled to be grouted in subsequent years. Pacific Northwest Laboratory (PNL) is verifying that Hanford grouts can be safely and efficiently processed. To meet this objective, pilot-scale grout process equipment was installed. The pilot-scale process equipment can produce grout at a rate of up to 25% of the maximum rate planned for the TGF. On July 29 and 30, 1986, PNL conducted a pilot-scale grout production test for Rockwell. During the test, 16,000 gallons of simulated nonradioactive PSW were mixed with grout formers to produce 22,000 gallons of PSW grout. The grout was pumped at a nominal rate of 15 gpm (""'2~% of the nominal production rate planned for the TGF) to a lined and covered trench with a capacity of 30,000 gallons. Emplacement of grout in the trench will permit subsequent evaluation of homogeneity of grout in a large monolith. The production of a i i i 22,000-yal monolith in a trench also permitted determination of curing characteristics, reabsorption of separated liquid, degree of cracking, and temperature rise expected with monolithic disposal. The principal process components-the grout mixer and the grout pump-are very similar to those planned for the Transportable Grout Facility Equipment (TGE). The pilot-scale test permitted evaluation of the performance of the mixer and pump, their flush requirements, and their reliability. In addition, representatives of the engineering firm commissioned to design and construct the processing equipment modules of the TGF observed the test to gain experience with processing grout. The test was very successful; major conclusions follow: • The continuous grout mixer and grout pump performed reliably, producing grout with acceptable properties. • The adiabatic grout temperature rise was at least 37°C, and probably higher. • The flow angle of grout in the trench averaged 1.5°. A similar flow angle can be expected in th...

Operations (Rockwell). Oak Ridge National laboratory (ORNL) has provided a grout formulation for Phosphate/Sulfate N-Reactor Waste, the first waste stream scheduled for grouting beginning in late 1987. The formulation includes a blend of portland cement, fly ash, attapulgite clay, and an illitic clay. Grout will be produced by mixing the blend with Phosphate/Sulfate N-Reactor Waste. These wastes result from decontaminatiOn and ion-exchange regeneration activities at Hanford 1 s N-Reactor. Pacific Northwest Laboratory (PNL) is conducting studies on grouted Phosphate/Sulfate N-Reactor Waste to verify that the grout can be successfully processed and, when hardened, that it will meet all performance and regulatory requirements.