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5 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2026

Tank 14H Preliminary Cease Waste Removal Sample Analyses

Savannah River Mission Completion Waste Removal and Tank Closure requested that Savannah River National Laboratory perform characterization analyses of Tank 14H in support of closure activities, specifically preliminary cease waste removal. This report provides important characterization of the prepared filtrate and air-dried solids in the January 2026 Tank 14H sample, HTF-14-26-1,2,3,4,5,6, for I-129, Tc-99, Cs-137, and Sr-90. The results reported here were utilized by SRMC to declare preliminary cease waste removal for Tank 14H.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2024

Waste Retrieval Enhancements to Achieve Preliminary Cease Waste Removal in Savannah River Site Liquid Waste Tanks 9H and 10H – 25348

The Liquid Waste (LW) contractor at the Savannah River Site (SRS) is Savannah River Mission Completion (SRMC). The LW Mission is tasked with processing legacy nuclear waste stored in underground waste tanks for final disposition. The Concentration, Storage, and Transfer Facilities (CSTF) contain 43 active waste tanks and 8 closed waste tanks between the two tank farms, F-Area Tank Farm (FTF) and H-Area Tank Farm (HTF). The first steps in the Waste Retrieval and Tank Closure (WRTC) process are the waste removal campaigns, consisting of either salt dissolution or sludge mobilization. Two tanks that are rapidly approaching the final closure determination and have demonstrated considerable success with salt dissolution are Tanks 9 and 10. The closure of these tanks is a high priority for the LW Mission due to the greater environmental risk they pose since both tanks reside within the water table and contain active leak sites from the primary tank to the annulus space. Tanks 9 and 10 have each recently completed their respective salt dissolution campaigns and achieved the Preliminary Cease Waste Removal (PCWR) milestone.

Stetson, Jacqueline G.↗
DOE OSTI2025

Characterization of Tank 15H Sample in Support of Preliminary Cease Waste Removal and Closure Mode Determination

The Savannah River National Laboratory (SRNL) was requested by Savannah River Mission Completion (SRMC) to provide sample preparation and analysis of Tank 15H characterization samples. These samples follow an interest in exploring avenues to condense the extensive sampling of the Tank Closure process. One such pathway would be to collect a sample during an earlier waste removal campaign for analysis to determine comparability to the later residual tank inventory determined through Residual Material sampling and characterization prior to grouting. Six Tank 15H samples (HTF-15-24-9, HTF- HTF-15-24-10, HTF-15-24-11, HTF-15-24-12, HTF15-24-13, and HTF-15-24-14) were delivered to SRNL in May of 2024. These six Tank 15H samples were taken as close as possible to the solids layer of the Tank 15H. These six Tank 15H samples were combined to form one composite sample for characterization due to the lack of sufficient solids fraction.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2026

Tank 11H Low Temperature Aluminum Dissolution and Inhalation Dose Potential Analyses at Savannah River Site – 26018

Currently, there is approximately 34 million gallons of high-level radioactive tank waste in the Tank Farm at the Savannah River Site (SRS). The ultimate goal of operations at the Tank Farm is to remove the high level waste (HLW) from the tanks followed by stabilization of the waste through vitrification of the HLW into glass or grouting the decontaminated waste into saltstone. After bulk removal of the HLW consisting of sludge, saltcake, and supernatant, further efforts are made to reduce the residual waste present in the tank in order to declare preliminary cease waste removal (PCWR) signifying completion of HLW removal. These reduction efforts can include tank washing to remove soluble salts and radioisotopes and dissolution of solids including aluminum. Aluminum in the form of gibbsite and boehmite is relatively insoluble in water. Through addition of aqueous sodium hydroxide, the aluminum can be dissolved at mild temperatures. In order for the waste tank to meet closure mode requirements of the Concentration, Storage, and Transfer Facilities (CSTF), which includes the Tank Farm, Documented Safety Analysis (DSA), a component of the safety basis, the inhalation dose potential (IDP) and the radiolytic hydrogen generation rate of the stored waste must be demonstrated to be lower than their respective designated limits. These parameters are calculated from measured radiochemical analyses of isotopes that emit a high amount of radioactivity including Cs-137, Sr-90, Pu-238, Pu-239, Pu-240, Pu-241, Am-241, and Cm-244. Following the low temperature aluminum dissolution (LTAD) process, Tank 11H slurry samples were pulled from the tank and sent to Savannah River National Laboratory (SRNL) to measure the extent of aluminum dissolution, hydroxide concentration, densities of slurry and supernatant, weight percent solids analyses, and radionuclide activities. The analyses of the composite sample found that approximately 90% of the total aluminum in the slurry was dissolved, indicating successful reduction of the insoluble aluminum in the waste tank. Additionally, the weight percent insoluble solids (slurry basis) measurement of the composite sample was found to be approximately 1%, demonstrating that minimal solids still remain in the tank. Finally, the radiochemical analyses of the composite sample determined that the waste contents of the tank met the IDP and radiolytic hydrogen generation rate requirements of the CSTF DSA. These measurements have shown that the LTAD process in Tank 11H was successful in waste reduction efforts and a positive step towards declaring PCWR and tank closure at SRS.

Dekarske, John [Savannah River National Laboratory↗