Executive Summary EM-21 is the Waste Processing Division of the Office of Engineering and Technology within the U.S. Department of Energy's (DOE) Office of Environmental Management (EM). In August 2008, EM-21began an initiative to develop a Retrieval Knowledge Center (RKC) to provide DOE, its high level waste retrieval operators, and technology developers with a focused effort to share knowledge and expertise for addressing retrieval challenges across the DOE complex. The RKC is also designed to facilitate information sharing across the DOE waste site complex through workshops and through the development of a searchable database of waste retrieval technology information. The database may be used to research effective technology approaches for specific retrieval tasks and to take advantage of the lessons learned from previous operations. It is also expected to be effective for remaining current with the state of the art in retrieval technologies and with ongoing technology development within the DOE complex. To encourage collaboration between DOE sites in solving waste retrieval issues, the RKC team is co-led by Savannah River National Laboratory (SRNL) and Pacific Northwest National Laboratory (PNNL).Two RKC workshops were held in Fall 2008. The purpose of these workshops was to define toplevel waste retrieval functional areas, exchange lessons learned, and develop a path forward to support a strategic business plan focused on technology needs for retrieval. The primary participants involved in these workshops included retrieval personnel and national laboratory staff associated with Hanford and the Savannah River Site, since the majority of remaining DOE waste tanks are located there. This report summarizes and documents the results of the initial RKC workshops. Technology challenges identified from these workshops and presented in this report are expected to set the direction for future RKCdirected tasks and facilitate tank waste retrieval solutions. v Acronyms and Abbreviations IntroductionThis document describes top-level waste retrieval functions and identifies areas of technical deficiencies related to future waste retrieval operations at U.S. Department of Energy (DOE) sites. Current and past waste retrieval work at DOE's Hanford and Savannah River Sites was assessed through two technical exchange workshops. This assessment also builds on past work performed by the Tanks Focus Area. The following appendices are provided as supplemental information related to previous workshops and retrieval activities: This information serves as the foundational basis for the Retrieval Knowledge Center (RKC) as defined in the background section below. Retrieval technology deficiencies identified in this document will be evaluated, prioritized, and then investigated as part of RKC's effort to facilitate DOE complexwide collaboration and waste retrieval solutions.Five primary waste retrieval functions are discussed in this report: Characterize Waste, Access Waste, Dislodge/Mobilize Waste, Convey Waste and Transport Waste....

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The transport properties of solid-liquid slurries having the same well-defined particle size distribution but different median particle sizes have been studied in a 22-mm I.D. horizontal pipeline flow loop. The solid-liquid slurries were glass beads-water mixtures. The particle size distribution of solids was Rosin-Rammler with median diameters of 50 mm and 250 mm. The relationship between the pressure drop in the straight horizontal sections of the flow loop and the mean slurry velocity was determined for different solids volume concentrations varying from 4.5 to 25% and mean slurry velocity ranging from 0.5 to 2.5 m/s. Critical deposition velocity was measured from visual observations. An existing empirical model of Wasp et al. that predicts the pressure gradient for a single-species slurry flow in a horizontal pipeline was used to describe the pressure drop data. The Oroskar-Turian correlation for critical velocity was used for comparison with the measured critical velocities.

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In the course of the U.S. Department of Energy’s (DOE) tank waste retrieval, immobilization, and disposal activities, high-level waste transfer lines have the potential to become plugged. In response to DOE’s needs, Florida International University’s Hemispheric Center for Environmental Technology (FIU-HCET) is studying the mechanism and behavior of pipeline plugging to determine the pipeline operating conditions for safe slurry transport. Transport behavior of multi-species slurry has been studied in a 1-in O.D. pipeline flow loop. The slurry was a five-species mixture of Fe2O3, Al2O3, MnO2, Ni2O3, and SiO2, which simulated actual waste at the Savannah River DOE site. The relationship between the pressure drop in the straight horizontal sections of the flow loop and the mean slurry flow velocity was determined for two solids volume concentrations of 5.2 and 7.8%. Critical deposition velocity was measured from visual observations. An existing empirical model that predicts the pressure gradient for a single-species slurry flow in a horizontal pipeline was used to describe the pressure drop data.