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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 1,693 records · Page 94
All sourcesNASA NTRSDOE OSTI
DOE OSTI2016

Advancements in the H-Canyon Exhaust Ventilation System Inspections at the Savannah River Site - 16030

A facility safety envelope requires management of activities to ensure no unacceptable radiological or chemical hazards to the public, site worker and environment occur. While appropriate design and construction methods ensure an initial physical plant configuration, what actions must an operating Facility take to ensure the physical plant continues to meet a safety configuration throughout Facility life? While a physical walk down of the plant is a tried and true method to confirm conditions, what other methods must be used when a walk down is not possible? What inspection methods are used when balancing budget pressures against obtaining inspection data? The periodic inspections of the H-Canyon Exhaust Tunnel are performed remotely. The 2015 remote Tunnel inspection has been the most successful inspection to date. This presentation highlights the continued lessons learned with the most recent 2015 remote Tunnel inspection. These lessons learned are applicable to Facilities considering or performing remote inspections. The Recovery Crawler Project was tasked with determining if the 2014 Inspection Crawler could be retrieved, perform the retrieval if feasible and complete the inspection of the remaining sections of the exhaust tunnel that were not previously performed. The objectives for the project were met, the Inspection Crawler was deemed unusable and left in place and the Recovery Crawler performed the complete 143 meters (470 feet) of tunnel inspection and an additional 55 meters (180 feet) of exhaust tunnel inspection not previously completed. The remote inspection of a 60+ year operating Canyon Exhaust tunnel is a complex endeavor requiring close coordination of multiple organizations, adherence to Conduct of Operations, Radiological Safety, Worker Safety, etc. principles as well as alignment with Facility Safety Basis requirements. This paper discusses the challenges, actions required getting ready for the 2015 recovery and continued inspection and the hazards encountered performing the actual recovery/inspection. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2018

Discovering Challenges and Opportunities During Sludge Removal in Savannah River Site's Tank 15 - 18415

Tank 15 is one of 43 active underground waste storage tanks in the Liquid Waste System at SRS. After receiving and storing waste containing insoluble solids (sludge), receipts stopped, and the free supernate evaporated beginning in the 1980's. Tank 15 remained a dry sludge tank for almost 30 years. In 2015, the Tank 15 sludge was rehydrated as the first step of waste removal. Submersible Mixer Pumps (SMPs) were then installed in four risers, as well as other equipment upgrades, to facilitate sludge solids removal. SMPs were successfully used in prior waste removal campaigns, but this was the first deployment of four in a tank. Automated controls were also added to better monitor and protect the SMPs during operation in the more challenging H-area sludge. Waste removal plans consisted of multiple campaigns where sludge was suspended, transferred to Tank 13 and supernate decanted back to Tank 15 for reuse after allowing solids to settle. During the first campaign, sludge solids did not settle at an adequate rate to support the operating plan, and flammability evaluations were impacted. The SMPs also experienced operational challenges. New control logic for the SMPs was useful for early identification of issues; however, some equipment failures still occurred. These challenges were overcome using a combination of additional analyses, operating plan and procedure changes, and tank mapping techniques resulting in the successful removal of the bulk of the sludge from Tank 15. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2018

Integrated Salt Waste Processing at the Savannah River Site - 18549

An intricate shoring system to provide protection to the workers and to critical components in the area was designed and installed. Designing and installing shoring systems is commonplace around the world, but installing it adjacent to high-level radioactive waste transfer lines nearly twenty feet in depth with tolerances within one-one thousandths of an inch required a more robust design. Upon completion, approximately 671 square meters (or 7,225 square feet) of sheet piling was installed without issue. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2019

Investigation of Thermolytic Production of Hydrogen Applicable to Savannah River Site High Level Waste - 19443

Several experiments have been performed to measure the generation rates of hydrogen gas due to reaction (thermolysis) of organic compounds in both simulated and radioactive waste. Initial measurements of hydrogen generation rates at 100 deg. C were made to downselect molecules and functional groups that produce significant amounts of hydrogen for subsequent kinetic determination. A statistically-designed test matrix was employed to quantitatively determine chemical conditions of highest reactivity at 100 deg. C. Additional experiments were performed at 100 deg. C to determine the impact of specific chemical components on hydrogen generation rates for relevant organic compounds. A semi-empirical model for thermolytic hydrogen generation rate from glycolate at 100 deg. C was developed and compared to results from radioactive waste and literature reports. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2020

Amplicon Sequencing Assessment to Measure Microbial Community Response from Heavy Metal Contaminated Soils in Savannah River site, Tims Branch watershed

Long-term presence of heavy metal contamination in soils is correlated with changes in microbial community structures and can lead to the reduction of indigenous species. Tolerance to soil heavy metal toxicity varies among different microbial communities. It remains unclear whether long term effects caused by metal perturbations are associated with soil microbial community dysregulation in Tims Branch watershed. Research Questions: Does heavy metal contamination in Tims Branch soils decrease microbial species diversity significantly compared to non-contaminated soils? Does the species richness decrease in contaminated samples? between samples? Is diversity in low, mid and high contamination soils significantly different compared to control samples? Hypothesis: The relative abundance and diversity of species are significantly altered in soils which are contaminated with heavy metals in the Tims Branch watershed. Objectives: Use amplicon sequencing technology along with bioinformatics to compare bacterial communities between four sites in Tims Branch watershed. Evaluate the percent relative abundance and diversity across the site. Conclusions: All bacterial communities exposed to different heavy metal concentrations were dominated by four major groups (Proteobacteria, Acidobacteria, Chloroflexi and Verrucomicrobia). The dominant phyla Proteobacteria, Acidobacteria and Chloroflexi accounted for 61 % of the relative abundance. Soil bacterial α-diversity, expressed as observed species richness metric and Shannon's diversity index, was the highest in sample location four (high contamination). The lowest observed was at the control location. Species richness increased when concentrations of heavy metals were localized, inferring that the metals can alter microbial community structure. PERMANOVA analysis between contaminated groups tested significant using the Adonis (F (4,29) =1.9712; p < 0.001). There is a 20 percent variation explained between groups (R2 = 0.214). This analysis proves to be beneficial in detecting microbial communities altered by contaminated soils. Moreover, certain concentrations of heavy metals can alter microbial community structures.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2020

Panel Session 55: US DOE Savannah River Operations Office: Liquid Waste Progress

This panel provided an overview of the SRS HLW Liquid Waste Program (history, challenges, opportunities, and future) including discussions of the Defense Waste Processing Facility (DWPF), Tank Closures, Actinide Removal Process/Modular Caustic Side Solvent Extraction Unit, Tank Closure Cesium Removal, and the Salt Waste Processing Facility (SWPF). Panelists with presentations: SRS Liquid Waste Program (James Folk); SRS Liquid Waste Progress (Mark Schmitz); Salt Waste Processing Facility (Frank Sheppard)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2025

Inspection and Mapping of Savannah River Site (SRS) Waste Tanks via Unmanned Aircraft System (UAS) – 25351

The CSTF at SRS contain 51 waste tanks with 8 closed waste tanks between FTF and HTF. SRMC is the LW contractor. The LW mission includes removing legacy nuclear waste from these tanks and treating it for final disposition. Once the bulk of the waste has been removed from a tank, it will undergo inspection and sampling to characterize the remaining waste in the tank prior to it being operationally closed. There are multiple points in the tank closure process where an inspection is performed, and there are multiple parts of a tank that get inspected. Waste tanks have a primary containment vessel (referred to as the “Primary”) and a secondary containment vessel (referred to as the “Annulus”) that surrounds the primary. Both of these sections of a tank receive multiple inspections throughout the closure process.

Murphy, Lucas D. [Savannah River Mission Completio↗
DOE OSTI2022

Respiration regimes in rivers: Partitioning source–specific respiration from metabolism time series

Respiration in streams is controlled by the timing, magnitude, and quality of organic matter (OM) inputs from internal primary production and external fluxes. Here, we estimated the contribution of different OM sources to seasonal, annual, and event-driven characteristics of whole-stream ecosystem respiration (ER) using an inverse modeling framework that accounts for possible time-lags between OM inputs and respiration. We modeled site-specific, dynamic OM stocks contributing to ER: autochthonous OM from gross primary production (GPP); allochthonous OM delivered during flow events; and seasonal pulses of leaf litter. OM stored in the sediment and dissolved organic matter (DOM) transported during baseflow were modeled as a stable stock contributing to baseline respiration. We applied this modeling framework to five streams with different catchment size, climate, and canopy cover, where multi-year time series of ER and environmental variables were available. Overall, the model explained between 53% and 74% of observed ER dynamics. Respiration of autochthonous OM tracked seasonal peaks in GPP in spring or summer. Increases in ER were often associated with high-flow events. Respiration associated with litter inputs was larger in smaller streams. Time lags between leaf inputs and respiration were longer than for other OM sources, likely due to lower biological reactivity. Model estimates of source-specific ER and OM stocks compared well with existing measures of OM stocks, inputs, and respiration or decomposition. Our modeling approach has the potential to expand the scale of comparative analyses of OM dynamics within and among freshwater ecosystems.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2025

Factors influencing water quality in surface water and alluvial groundwaters downgradient of a reclaimed surface coal mine in the Powder River Basin of southeastern Montana, USA

Abstract Coal mining and reclamation can have a profound influence on hydrogeologic systems, with clear consequences for groundwater quality, yet their long-term influence on downgradient water quality over time following reclamation is less well documented. Geochemical trends were evaluated in water quality downgradient of a fully reclaimed landscape at the former Big Sky Mine in the Rosebud Creek watershed (southeastern Montana, USA), over a 3-year period (2020–2022), including bond release in 2022. Within 6 km downgradient from the reclaimed area, sulfate concentrations decreased from approximately 3500 to 1800 mg l −1 within the Miller Coulee alluvial aquifer. Major ions, δ 34 S SO4 values, and residence time tracers suggest that the observed decreases in sulfate concentration result from a combination of dilution by mixed-age inflows and incomplete transit of the high salinity plume from the mine boundary. Both bedrock and alluvial aquifers of the Rosebud Creek corridor contained contributions of millennia-old regional groundwater, which may serve to mitigate mine-derived high salinity waters. Rosebud Creek, which traverses the outflow zone of Miller Coulee in the study area, exhibited high sulfate concentrations during low flows and consistent downgradient increases in sulfate concentration. The possibility of plume dynamics in Miller Coulee suggests that the greatest water quality impacts may not yet have reached Rosebud Creek.

Keeshin, Skye I. (ORCID:0009000986449872)↗
DOE OSTI2021

Comparison of Observations and Predictions of Daytime Planetary-Boundary-Layer Heights and Surface Meteorological Variables in the Columbia River Gorge and Basin During the Second Wind Forecast Improvement Project

The second Wind Forecast Improvement Project (WFIP2) is an 18-month field campaign in the Pacific Northwest U.S.A., whose goal is to improve the accuracy of numerical-weather-prediction forecasts in complex terrain. The WFIP2 campaign involved the deployment of a large suite of in situ and remote sensing instrumentation, including eight 915-MHz wind-profiling radars, and surface meteorological stations. The evolution and annual variability of the daytime convective planetary-boundary-layer (PBL) height is investigated using the wind-profiling radars. Three models with different horizontal grid spacing are evaluated: the Rapid Refresh, the High-Resolution Rapid Refresh, and its nested version. The results are used to assess errors in the prediction of PBL height within the experimental and control versions of the models, with the experimental versions including changes and additions to the model parametrizations developed during the field campaign, and the control version using the parametrizations present in the National Oceanic and Atmospheric Administration/National Centers for Environmental Prediction operational version of the models at the start of the project. Results show that the high-resolution models outperform the low-resolution versions, the experimental versions perform better compared with the control versions, model PBL height estimations are more accurate on cloud-free days, and model estimates of the PBL height growth rate are more accurate than model estimates of the rate of decay. Finally, using surface sensors, we assess surface meteorological variables, finding improved surface irradiance and, to a lesser extent, improved 2-m temperature in the experimental version of the model.

54 ENVIRONMENTAL SCIENCES↗