The Savannah River Site Accelerated Cleanup Mission: Sludge Retrieval and Immobilization
Approximately 130 million liters of sludge/supernate high-level radioactive waste (HLW) is currently stored in underground carbon steel tanks at the Savannah River Site (SRS) in Aiken, South Carolina. The Defense Waste Processing Facility (DWPF) began immobilizing these wastes in borosilicate glass in 1996. Currently, the radioactive glass is being produced as a sludge-only composition by combining washed high-level sludge with glass frit and melting. The glass is poured into stainless steel canisters for eventual disposal in a permanent geological repository. Recent directives from the U.S. Department of Energy have been focused on accelerated clean-up missions for the various sites around the DOE complex. The Savannah River Site has developed a program to meet this new directive. With respect to the DWPF, a vision case has been developed which reduces the overall immobilization campaign by several years. This reduction is based on several parameters; two of which are increase s in melt rate and waste loading. To support this incentive, the Savannah River Technology Center is focusing on increasing waste loading and/or improving melt rates via strategic glass formulation, changes in acid addition strategies, and reassessing process control models to challenge their extreme conservatism. Glass formulation activities have recently shifted from the strategy of using generic frits developed to process a number of different sludge batches, to the concept of developing a specific frit for each sludge batch in order to obtain higher waste loadings and/or improved melt rates. Increases in waste loading have also been realized by the development of a new liquidus temperature model - a parameter which has typically limited waste loadings in previous processing. Coupling the new liquidus model with strategic glass formulations will result in an increase in overall waste throughput. Assessments are also being made on the potential to minimize the number of sludge w ashing steps to minimize the volume of wash water (ultimately treated by the high-level waste evaporators) without compromising processability, product quality, or waste throughput goals. In order for DWPF to process the waste faster, retrieval of sludge from the waste tanks must be accelerated. Acceleration of sludge retrieval will focus on developing technologies to reduce the time and cost to retrieve the bulk of the sludge waste from tanks, retrieve residual heels, and retrieve waste from the annulus of tanks that have leaked. Much of the cost for the retrieval infrastructure can be attributed to the elaborate support structure that must be built, spanning the tank top, to support the four mixing pumps and the transfer pump. Previous work has shown through testing of a high capacity Advanced Design Mixer Pump (ADMP) that the number of mixer pumps necessary to mobilize the waste could be reduced by half.
- Research Organization:
- Savannah River Site (SRS), Aiken, SC (United States)
- Sponsoring Organization:
- US Department of Energy (US)
- DOE Contract Number:
- AC09-96SR18500
- OSTI ID:
- 808205
- Report Number(s):
- WSRC-MS-2003-00053; TRN: US0301986
- Resource Relation:
- Conference: Waste Management 2003, Tucson, AZ (US), 02/23/2003--02/27/2003; Other Information: PBD: 18 Feb 2003
- Country of Publication:
- United States
- Language:
- English
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