For years, the U.S. Department of Energy has been storing a witches' brew of radioactive and hazardous materials in underground tanks. To manage this waste, tank operators need safe, cost-effective methods of mixing tank material, transferring tank waste between tanks, and taking samples. The current methods for accomplishing these tasks are expensive, labor-intensive, increase the risks of worker exposure to radiation, and often produce nonrepresentative and unreproducable samples. DOE's Office of Science and Technology (EM-50) and Office of Waste Management (EM-30) are working with AEA Technology, a private technology development and engineering company, to make the job of processing tank waste safer and more economical. They are demonstrating and deploying Power Fluidic devices, a series of maintenance-free pumps, mixers, and samplers. Power Fluidic devices have been used in nuclear installations in the United Kingdom for the past 20 years, and more than 400 systems have been installed with no failures, to date. They offer an alternative to mechanical pumps, which are generally more expensive, produce large volumes of secondary waste, and tend to fail frequently, increasing the risk to maintenance workers. Steam jets require less maintenance but have limited ability to pump solid/liquid mixtures, operate on one fixed flow rate, and heat and dilute tank contents. OST has supported two full-scale demonstrations of three Power Fluidic devices-a sampler, a reverse-flow divertor pump, and a fluidic diode pump-at AEA Technology's facilities in North Carolina and the United Kingdom. The success of these demonstrations has resulted in two additional contracts, jointly funded by EM-50 and EM-30, to deploy these technologies at two DOE sites, Oak Ridge and Savannah River. Mixing it up at Oak Ridge The Bethel Valley Evaporator Storage Tanks at Oak Ridge National Laboratory contain sludges that have been settling for many years. To return these tanks to service, these sludges must first be transferred to other tanks; but thick sludges and limited access to the tanks make installation of a system difficult. There are, however, six sludge jets, which can be used as a basis for a pulse-jet mixer system. This resilient and low-maintenance system mixes and homogenizes the waste and is comparatively easy and cost-effective to install and operate. This same equipment can later be used to mobilize wastes stored in other Bethel Valley tanks to support transuranic waste disposal and at other DOE sites having horizontal tanks, like the Idaho National Engineering and Environmental Laboratory. Taking Samples at Savannah River As part of tank cleanup at SRS, workers will use precipitation to remove high-activity cesium from Tank 48. Filters will then remove the potassium/cesium tetraphenylborate precipitate from Tank 48, and pumps will move the precipitate to a staging tank, Tank 49. After removal of the cesium, Tank 48 will contain a decontaminated salt solution, which can be treated later. Tank 49 will then be ready for treatment of its high-activity cesium. The in-tank precipitation process requires frequent and accurate sampling of Tanks 48 and 49 to characterize contents both during Tank 48's precipitation process and before Tank 49's treatment. Currently, samples are obtained from the tanks by taking dip samples at or near the surface of the liquid. However, this method does not allow sampling from a range of tank depths or provide representative samples as required for in-tank precipitation. Dip sampling also requires more extensive worker protection measures and increases the risk of environmental contamination. In addition, the tank contents are held under an inert nitrogen atmosphere, which must not be removed during the sampling process. This condition limits the possible technologies that can be used. Fluidic samplers are no-maintenance components that are safer to use and produce more representative samples than dip samplers. A fluidic sampler consists of a reverse-flow divertor pump with a specially designed sampling tee installed in the discharge pipework, which delivers a sample of the liquid through a sample needle to a sample bottle. The flow from a fluidic pump is intermittent; i.e., delivery of liquid is followed by a period when the pump is refilling. This process results in a much more representative sample, because it has been collected over a number of pumping cycles. A typical arrangement and mode of operation are illustrated below. Power Fluidic devices offer DOE site operators major benefits in both cost savings and improved safety for a number of mixing, pumping, and sampling operations. The collaboration between EM-50, EM-30, and AEA Technology is taking Power Fluidic equipment demonstrated in a nonactive environment (with EM-50 support) and deploying it in the field at ORNL and SRS (with both EM-30 and EM-50 support). This effort is helping to solve major operational problems which, if not addressed, will have a significant impact on the ability of sites to meet their cleanup deadlines. Laurie Judd, program manager for DOE programs at AEA Technology, said about the project, "The transition from original idea to full-scale deployment has taken about 12 months to achieve and is testimony to the excellent working relationship between OST, site operators, and AEA Technology." For more information, contact Laurie Judd at AEA Consultancy Services, Inc., 8150 Leesburg Pike, Suite 700, Vienna, VA 22182, call (703) 748-4810, fax (703) 748-4811, laurie.judd@aeat.co.uk.