Savannah River Site Disposal Facility for Waste Incidental to Reprocessing
The Savannah River Site (SRS), owned by the U.S. Department of Energy (DOE), occupies an area of approximately 780 km2 (300 mi2) in western South Carolina. Since its establishment in 1951, SRS has produced nuclear material for national defense, research, medical applications, and space programs. As a result of these activities, SRS now has significant quantities of radioactive waste stored onsite in large underground waste storage tanks. Over the years, however, the waste resulting from reprocessing spent nuclear fuel for defense purposes has been commingled with other types of waste resulting from manufacturing targets for nuclear weapons and fabricating materials for space missions.
DOE now intends to remove, stabilize, and dispose of the waste, and close all 49 operational waste storage tanks at SRS. The sludge (insoluble metal hydroxide solids) is currently being stabilized in the Defense Waste Processing Facility (DWPF) through a vitrification process, which immobilizes the waste in a borosilicate glass matrix for eventual disposal in a Federal repository. In order to continue to have adequate tank farm space to support DWPF operations and startup of the Salt Waste Processing Facility (SWPF), however, DOE has indicated that it needs to remove a portion of the salt waste in the near term. For additional detail, see the following topics on this page:
SRS Waste Characterization
SRS currently has a total of 51 underground waste storage tanks, all of which were placed into operation between 1954 and 1986. Of those 51 tanks, only 27 meet the current requirements, established by the U.S. Environmental Protection Agency (EPA), for full secondary containment and leak detection. Another 2 tanks, which did not have secondary containment, have already been closed and grouted. The remaining 22 tanks do not have full secondary containment and do not meet EPA requirements. (Of those 22 tanks without secondary containment, 12 have a history of leakage, but sufficient waste has been removed so that those tanks currently have no active leak sites.) Of the 49 tanks that remain in operation, 29 are in the H-Tank Farm and 20 are in the F-Tank Farm.
The SRS waste storage tanks currently hold approximately 1.34 x 108 liters (L) [3.64 x 107 gallons (gal)] of waste, containing 1.58 x 1019 Becquerels (Bq) [4.26 x 108 Curies (Ci)] of radioactivity. This waste is a mixture of insoluble metal hydroxides (referred to as sludge), and soluble salt supernatant (the liquid above a precipitate or sediment). The volume of supernatant has been reduced by evaporation, which also concentrates the soluble salts to the limits of their solubility. The resultant solution crystallizes as salts, and the resulting solid is referred to as saltcake. The combined saltcake and supernatant, referred to as salt waste, comprise 1.25 x 108 L (3.38 x 107 gal) (93% of the total waste volume), and contributes 8.25 x 1018 Bq (2.23 x 108 Ci) (52% of the total radioactivity). The sludge comprises 9.6 x 106 L (2.6 x 106 gal) (7% of the total waste volume), and contributes 7.51 x 1018 Bq (2.03 x 108 Ci) (48% of the total radioactivity).
In March 2005, DOE submitted a draft waste determination, describing its plan to dispose of the salt waste at SRS. In particular, DOE proposed to remove salt waste from the 49 operational waste tanks at SRS, treat the waste with various processes to remove some of the radionuclides in the waste, and solidify the treated salt waste by mixing it with dry grout ingredients to form a cementitious wasteform called saltstone.
Based on a review of DOE's draft waste determination and supporting documents, the NRC staff concluded that there is reasonable assurance that the salt waste will meet the applicable criteria for designation as waste incidental to reprocessing (WIR), provided that several key assumptions are verified during monitoring. This conclusion and the NRC staff's review are documented in the Technical Evaluation Report for SRS Saltstone Disposal, and the NRC staff issued its related Monitoring Plan in May 2007.
The NRC's performance assessment staff also supported the SRS Saltstone monitoring visits with expertise in engineered barrier performance, environmental monitoring, and other relevant areas. Onsite observation reports are available for the following monitoring visits to the Saltstone site:
SRS F-Tank Farm
On August 25, 2008, the NRC received DOE's Performance Assessment for the SRS F-Tank Farm, and the staff subsequently provided comments on that document. In addition, upon receipt of DOE's waste determination and final performance assessment, the staff will conduct a technical review of the waste determination and complete a technical evaluation report, in accordance with the guidance set forth in NUREG-1854, “NRC Staff Guidance for Activities Related to U.S. Department of Energy Waste Determinations.”