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Title: SAVANNAH RIVER SITE TANK 48H WASTE TREATMENT PROJECT TECHNOLOGY READINESS ASSESSMENT

Conference ·
OSTI ID:1028097

One of U.S. Department of Energy's (DOE) primary missions at Savannah River Site (SRS) is to retrieve and treat the high level waste (HLW) remaining in SRS tanks and close the F&H tank farms. At present, a significant impediment to timely completion of this mission is the presence of significant organic chemical contamination in Tank 48H. Tank 48H is a 1.3 million gallon tank with full secondary containment, located and interconnected within the SRS tank system. However, the tank has been isolated from the system and unavailable for use since 1983, because its contents - approximately 250,000 gallons of salt solution containing Cs-137 and other radioisotopes - are contaminated with nearly 22,000 Kg of tetraphenylborate, a material which can release benzene vapor to the tank head space in potentially flammable concentrations. An important element of the DOE SRS mission is to remove, process, and dispose of the contents of Tank 48H, both to eliminate the hazard it presents to the SRS H-Tank Farm and to return Tank 48H to service. Tank 48H must be returned to service to support operation of the Salt Waste Processing Facility, to free up HLW tank space, and to allow orderly tank closures per Federal Facility Agreement commitments. The Washington Savannah River Company (WSRC), the SRS prime contractor, has evaluated alternatives and selected two processes, Wet Air Oxidation (WAO) and Fluidized Steam Bed Reforming (FBSR) as candidates for Tank 48H processing. Over the past year, WSRC has been testing and evaluating these two processes, and DOE is nearing a final technology selection in late 2007. In parallel with WSRC's ongoing work, DOE convened a team of independent qualified experts to conduct a Technology Readiness Assessment (TRA). The purpose of the TRA was to determine the maturity level of the Tank 48H treatment technology candidates - WAO and FBSR. The methodology used for this TRA is based on detailed guidance for conducting TRAs contained in the Department of Defense (DoD), Technology Readiness Assessment Deskbook. The TRA consists of three parts: (1) Determination of the Critical Technology Elements (CTEs) for each of the candidate processes. (2) Evaluation of the Technology Readiness Levels (TRLs) of each CTE for each process. (3) Defining of the technology testing or engineering work necessary to bring immature technologies to the appropriate maturity levels. The TRA methodology assigns a TRL to a technology based on the lowest TRL assigned to any CTE of that technology. Based on the assessment, the overall TRL for WAO was 2 and the TRL for FBSR was 3. WAO was limited by the current lack of definition for the off-gas treatment system (TRL of 2). The FBSR Product Handling had little or no test work and therefore received the lowest score (TRL of 3) for the FBSR CTEs. In summary, both FBSR and WAO appear to be viable technologies for treatment of Tank 48H legacy waste. FBSR has a higher degree of maturity than WAO, but additional technology development will be required for both technologies. However, the Assessment Team believes that sufficient information is available for DOE to select the preferred or primary technology. Limited testing of the backup technology should be conducted as a risk mitigation strategy.

Research Organization:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Sponsoring Organization:
USDOE
DOE Contract Number:
AC05-76RL01830
OSTI ID:
1028097
Report Number(s):
PNNL-SA-58108; 830403000; TRN: US1105322
Resource Relation:
Conference: Waste Management Symposium 2008: Phoenix Rising - Moving Forward in Waste Management: February 24-28, 2008, Phoenix, Arizona., Paper No. 8143
Country of Publication:
United States
Language:
English