Effect of Mercury-Noble Metal Interactions on SRAT Processing of SB3 Simulants (U)
Controlling hydrogen generation below the Defense Waste Processing Facility (DWPF) safety basis constrains the range of allowable acid additions in the DWPF Chemical Processing Cell. This range is evaluated in simulant tests at the Savannah River National Laboratory (SRNL). A minimum range of allowable acid additions is needed to provide operational flexibility and to handle typical uncertainties in process and analytical measurements used to set acid additions during processing. The range of allowable acid additions is a function of the composition of the feed to DWPF. Feed changes that lead to a smaller range of allowable acid additions have the potential to impact decisions related to wash endpoint control of DWPF feed composition and to the introduction of secondary waste streams into DWPF. A limited program was initiated in SRNL in 2001 to study the issue of hydrogen generation. The program was reinitiated at the end of fiscal year 2004. The primary motivation for the study is that a real potential exists to reduce the conservatism in the range of allowable acid additions in DWPF. Increasing the allowable range of acid additions can allow decisions on the sludge wash endpoint or the introduction of secondary waste streams to DWPF to be based on other constraints such as glass properties, organic carbon in the melter off-gas, etc. The initial phase of the study consisted of a review of site reports and off-site literature related to catalytic hydrogen generation from formic acid and/or formate salts by noble metals. Many things are already known about hydrogen generation during waste processing. This phase also included the development of an experimental program to improve the understanding of hydrogen generation. This phase is being documented in WSRC-TR-2002-00034. A number of areas were identified where an improved understanding would be beneficial. A phased approach was developed for new experimental studies related to hydrogen generation. The first phase of new experimental work consisted of six simulations of the DWPF Sludge Receipt and Adjustment Tank (SRAT). This phase had four objectives, but the primary focus was on the effect of mercury on hydrogen generation and SRAT processing. These objectives were to: (1) Obtain SRAT processing data at three different mercury concentrations. (2) Obtain comparable data for mercury added as HgO or as Hg(NO{sub 3}){sub 2}. (3) Obtain process data that could lead to more prototypical performance of the experimental equipment. (4) Use data from enhanced gas chromatographs to improve the understanding of acid consumption during processing.
- Research Organization:
- Savannah River Site (SRS), Aiken, SC
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- DE-AC09-96SR18500
- OSTI ID:
- 881515
- Report Number(s):
- WSRC-TR-2004-00548; TRN: US0603116
- Country of Publication:
- United States
- Language:
- English
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