SRAT CHEMISTRY AND ACID CONSUMPTION DURING SIMULATED DWPF MELTER FEED PREPARATION
Due to higher than expected hydrogen generation during the Tank 51-Sludge Batch 4 (SB4) qualification run, DWPF engineering requested the Savannah River National Laboratory (SRNL) to expand the ongoing catalytic hydrogen generation program. The work presented in this Technical Report was identified as part of SRNL/Liquid Waste Organization (LWO) meetings to define potential causes of catalytic hydrogen generation as well as from an external technical review panel commissioned to evaluate SRNL hydrogen related data and programs. New scope included improving the understanding of SRAT/SME process chemistry, particularly as it related to acid consumption and hydrogen generation. The expanded hydrogen program scope was covered under the technical task request (TTR): HLW-DWPF-TTR-2007-0016. A task technical and quality assurance plan (TT&QAP) was issued to cover focus areas raised in meetings with LWO plus a portion of the recommendations made by the review panel. A supporting analytical study plan was issued. It was also noted in the review of catalytic hydrogen generation that control of the DWPF acid stoichiometry was an important element in controlling hydrogen generation. A separate TTR was issued to investigate ways of improving the determination of the acid requirement during processing: HLWDWPF-TTR-0015. A separate TT&QAP was prepared for this task request. This report discusses some progress on this task related to developing alternative acid equations and to performing experimental work to supplement the existing database. Simulant preparation and preliminary flowsheet studies were already documented. The prior work produced a sufficient quantity of simulant for the hydrogen program and melter feed rheology testing. It also defined a suitable acid addition stoichiometry. The results presented in this report come from samples and process data obtained during sixteen 22-L SRAT/SME simulations that were performed in the second half of 2007 to produce eight SME products with frit 418 and a matching set of eight SME products with spherically beaded frit 418. The requirement to produce two 25 gallon batches of melter feed for the melter feed rheology modifier program fell under a separate task plan. One supporting 4-L SRAT simulation was performed with mercury, since the 22-L melter feed preparation runs had no mercury due to melter off-gas constraints. As a result of this work, a timeline of reactions has been developed showing the sequence of major reactions occurring during and shortly after acid addition. The traditional-style simulant used in this testing had fairly well defined speciation which enabled the reactions being observed to be related to acid consumption. The new coprecipitated simulants have somewhat different speciation, and it will be necessary to validate some of the conclusions from this testing using sample data from SRAT simulations with coprecipitated simulant. Noble metal dissolution data on timing and concentration were presented in a separate report discussing hydrogen generation. A few of those results will be brought into this report as part of the description of the SRAT chemistry timeline. The noble metal and mercury concentrations used in the preliminary flowsheet studies are summarized in Table 1 along with the ranges covered in this study.
- Research Organization:
- Savannah River Site (SRS), Aiken, SC (United States)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- DE-AC09-08SR22470
- OSTI ID:
- 945384
- Report Number(s):
- WSRC-STI-2008-00131; TRN: US200903%%212
- Country of Publication:
- United States
- Language:
- English
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