Pilot-scale grout production test with a simulated low-level waste

Abstract

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...

Pilot-scale production of grout with simulated double-shell slurry feed. Final report

“…The equipmentdescribed in this report produces grout at up to 25% of the TGE processingrate. The equipment was used previouslyin a 24-hr processingstudy of PSW grout production (Fow et al 1987).…”

“…The amount of wear was quantifiedby measuringthe increase in the width of the worn tip on the mixer. Prior to this pilot-scaletest the maximum width of the worn sectionwas 0.24 in., which representedthe wear that resulted from the previous pilot-scaleproductionof PSW grout (Fow et al 1987). After the DSSF grout production,the width of this worn…”

Analysis of Tank 241-AN-106 characterization and grout performance criteria

“…A pilot-scalestudy was conductedin July 1986 to evaluate grout properties that will affect processabilityand to provide a preliminaryindication of "larje" scale grout propertiessuch as leachability,compressivestrength, and drainable liqu;ds (Fow et al 1987, Lokken et al 1988. Equal volumes of phosphate and su!fatewastes were used in the study.…”

Characterization of double-shell slurry feed grout produced in a pilot-scale test. Hanford Grout Technology Program

“…Both processes use the same type of dry solids, and the major constituents in the waste solutions are the same (i.e., NAN03, NAN02, NaAI(OH)4 and NaOH). (Lokken et al 1987), radioactive grout leach testing (Serne et al 1987), performance assessments (Sewart et al 1987), and pilot-scale tests (Fow et al 1987). A major pilot-scale test was performed in 1986 with a simulated phosphate/sulfate waste (PSW) to assess the effectiveness of the grouting operations and to characterize the grout produced with pilot-scale equipment and cured in a large mass.…”

“…A major pilot-scale test was performed in 1986 with a simulated phosphate/sulfate waste (PSW) to assess the effectiveness of the grouting operations and to characterize the grout produced with pilot-scale equipment and cured in a large mass. The results of that test are presented in Fow et al (1987), , and Lokken and Mitchell (1988…”