ANALYSIS OF SAMPLES FROM TANK 6F CHEMICAL CLEANING
Savannah River Remediation (SRR) is preparing Tank 6F for closure. The first step in preparing the tank for closure is mechanical sludge removal. In mechanical sludge removal, personnel add liquid (e.g., inhibited water or supernate salt solution) to the tank to form a slurry. They mix the liquid and sludge with pumps, and transfer the slurry to another tank for further processing. Mechanical sludge removal effectively removes the bulk of the sludge from a tank, but is not able to remove all of the sludge. In Tank 6F, SRR estimated a sludge heel of 5,984 gallons remained after mechanical sludge removal. To remove this sludge heel, SRR performed chemical cleaning. The chemical cleaning included two oxalic acid strikes, a spray wash, and a water wash. SRR conducted the first oxalic acid strike as follows. Personnel added 110,830 gallons of 8 wt % oxalic acid to Tank 6F and mixed the contents of Tank 6F with two submersible mixer pumps (SMPs) for approximately four days. Following the mixing, they transferred 115,903 gallons of Tank 6F material to Tank 7F. The SMPs were operating when the transfer started and were shut down approximately five hours after the transfer started. SRR collected a sample of the liquid from Tank 6F and submitted it to SRNL for analysis. Mapping of the tank following the transfer indicated that 2,400 gallons of solids remained in the tank. SRR conducted the second oxalic acid strike as follows. Personnel added 28,881 gallons of 8 wt % oxalic acid to Tank 6F. Following the acid addition, they visually inspected the tank and transferred 32,247 gallons of Tank 6F material to Tank 7F. SRR collected a sample of the liquid from Tank 6F and submitted it to SRNL for analysis. Mapping of the tank following the transfer indicated that 3,248 gallons of solids remained in the tank. Following the oxalic acid strikes, SRR performed Spray Washing with oxalic acid to remove waste collected on internal structures, cooling coils, tank top internals, and tank walls. The Acid Spray Wash was followed by a Water Spray Wash to remove oxalic acid from the tank internals. SRR conducted the Spray Wash as follows. Personnel added 4,802 gallons of 8 wt % oxalic acid to Tank 6F through the spray mast installed in Riser 2, added 4,875 gallons of oxalic acid through Riser 7, added 5,000 gallons of deionized water into the tank via Riser 2, and 5,000 gallons of deionized water into the tank via Riser 7. Following the Spray Wash, they visually inspected the tank and transferred 22,430 gallons of Tank 6F material to Tank 7F. SRR collected a sample of the liquid from Tank 6F and submitted it to SRNL for analysis. Following the Spray Wash and transfer, Savannah River Site (SRS) added 113,935 gallons of well water to Tank 6F. They mixed the tank contents with a single SMP and transferred 112,699 gallons from Tank 6F to Tank 7F. SRR collected a sample of the liquid from Tank 6F and submitted to SRNL for analysis. Mapping of the tank following the transfer indicated that 3,488 gallons of solids remained in the tank. Following the Water Wash, SRR personnel collected a solid sample and submitted it to SRNL for analysis to assess the effectiveness of the chemical cleaning and to provide a preliminary indication of the composition of the material remaining in the tank.
- Research Organization:
- Savannah River Site (SRS), Aiken, SC (United States)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- DE-AC09-08SR22470
- OSTI ID:
- 1009567
- Report Number(s):
- SRNL-STI-2009-00493; TRN: US1101555
- Country of Publication:
- United States
- Language:
- English
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