Uranium Attenuated by a Wetland 50 Years after Release into a Stream

Abstract

 1 background information section entitled, "Waste Generated from the SRS Fuel Fabrication Facility." 1. Figure S1. Historical uranium releases to streams from the Savannah River Site's Fuel Fabrication Facility (data provided in Evans et al. 1992). 2. Figure S2. Expanded map of uranium activity in Tim's Branch, including 291,000 gamma spectra acquisitions (1 second per measurement). 3. Figure S3. Images taken during gamma survey. (Left) Surveyor carrying computer tablet and 7.3 kg backpack equipped with a NaI detector, control module (multi-channel analyzer) and GPS system. (Right) A screenshot of the computer tablet showing the real-time position of the surveyor (black icon), survey transect lines (green lines), satellite image of terrain, and map of total gamma emissions prior of each 1-second acquisition (dots with colors corresponding to intensity of detected gamma emissions). Screenshot taken while surveying the A-14 Delta. 4. Section: Waste Generated from the SRS Fuel Fabrication Facility

Uranium Immobility in Tims Branch Wetland

“…Integrating the gamma mapping data (Figure 1) with the depth profile data (Figure 3) required accounting for gamma shielding by the two types of depth profiles (continuous decreasing and deposition profiles). Details of how this was accomplished is presented in Kaplan et al (2020). Additionally, a first-approximation estimate of the U inventory based entirely on soil cores U depth profiles was calculated (not accounting for shielding) and compared to the gamma spectral estimate.…”

“…These data were used to estimate the mass of background-corrected U remaining in the wetland. Details regarding the gamma measurements and data handling, soil U measurements, and calculations are presented in Kaplan et al (2020).…”

“…Desorption Kd Measurements: Site-specific Kd values were measured using a batch desorption protocol (ASTM, 2010) and the depth-discrete sediment samples retrieved from the cores collected as part of the mapping study described above (Kaplan et al, 2020). A gram of each sample and 15 mL of water were placed in a 15-mL centrifuge tube and the suspension was placed on a shaker for 2 weeks to come to steady state.…”

“…The Tims Branch wetland has been extremely effective for the last 50 years at immobilizing U released to the system. A detailed map including 270,000 gamma spectra of the U distribution in the wetland indicated that 84% of the initial 43,500 kg U introduced in the system remain there after 50 years (Kaplan et al, 2020). The effectiveness of immobilizing U is supported by stream water measurements collected over the last several decades indicating that U concentrations have B. T. Butcher SRNL-STI-2021-00081, Rev.…”

Radionuclides of the Savannah River Site Environment: Recent Data and Monitoring Techniques in Support of WAES TTX#3

“…Figure 3-7 shows the annual releases of uranium from M-Area. It has been shown that about 83 percent (36.2 metric tonnes) still remains in the wetland areas of Tims Branch (Kaplan et al, 2020).…”