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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 1,063 records · Page 59
All sourcesNASA NTRSDOE OSTI
DOE OSTI2013

Performance Impact of Fast Flow Paths Through Grout Monoliths Used for Radioactive Waste Disposal - 13224

Empty HLW handling and storage tanks at SRS and INL contain residual radioactivity; these tanks are being stabilized with cementitious grout during closure operations. The US NRC directed the Center for Nuclear Waste Regulatory Analyses (CNWRA{sup R}) to develop physical analogs of cementitious grout monoliths to investigate their potential to form fast flow pathways such as macro-cracks, separations between grout lifts, and annuli around pipes, supports, and along tank walls. CNWRA developed and tested 15 55-gal-drum-scale specimens and 2 larger specimens of tank-filling cementitious grout, and 9 specimens of pipe-filling grout. These experiments demonstrated that the size of fast flow pathways that develop and the peak temperatures attained during hydration are proportional to the scale of the specimen, and that annular apertures and bulk grout permeability generally increased with time post-placement. Cracks developed overnight following placement of each grout lift in the largest specimen, but developed more slowly in smaller specimens, perhaps due to a ∼20 deg. C difference in peak temperatures, which influence the thermal gradients that can induce cracking. Plastic and drying shrinkage commonly led to poor grout-to-metal and grout-to-grout bonding. Cracks, annular gaps, and grout flow lobe seams transmitted fluids during injection testing. Macro-scale flow pathways such as these are not readily observed in bench-scale specimens of cementitious tank grout. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2013

Long-term Performance of Engineered Barrier Systems (PEBS) - An International EURATOM Project on the Study and Testing of Engineered Barriers for the Final Disposal of HAW Using PEBS as an Example - 13299

The main aim of the PEBS project is to evaluate the sealing and barrier performance of the EBS over time, through development of a comprehensive approach involving experiments, model development, and consideration of the potential impacts on long-term safety functions. The experiments and models cover the full range of conditions, from initial emplacement of wastes (high heat generation and EBS re-saturation) through to later stage establishment of near steady state conditions, i.e. full re-saturation and thermal equilibrium with the host rock. These aspects will be integrated in a manner that will lead to greater certainty and thus greater confidence regarding the development from the initial transient state of the EBS to its long-term state, which provides the required isolation of the wastes. The work proposed within the project builds on existing knowledge and experience generated during recent years and supported by ongoing national and EC research programs. The project aims to provide a more complete description of the THM and THMC (thermo-hydro-mechanical- chemical) evolution of the EBS system, a more quantitative basis for relating the evolutionary behavior to the safety functions of the system, and a further clarification of the significance of residual uncertainties for long-term performance assessment. The importance of uncertainties arising from potential disagreement between the process models and the laboratory and in-situ experiments to be performed within PEBS, and their implications for an extrapolation of the results, will be reviewed, with particular emphasis on possible impacts on safety functions. In addition to the scientific-technical aims, the consortium will disseminate the basic findings to the broad scientific community within the EU, China and Japan, use expertise gained for public information purposes, and promote knowledge and technology transfer through training. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2015

Experience in environmental remediation of radioactively contaminated site in waste disposal area in Istanbul - 15011

In this paper specific environmental remediation examples of method applications are given. Radiological contaminated site was created by non-nuclear industry in Turkey. This is designated as a contaminated site and can ultimately lead to undesired health effects for residents. Appropriate actions have been taken to protect human and environment from contaminated site. As every site has its own characteristics, contaminated area was examined by sampling and surveying works. Before taken into action, remediation actions need to be justified and optimized. Radiation levels and homogeneity of contamination was investigated. Remediation program was established and taken into action in parallel two main works. First one covers all actions to the contamination itself. The site was isolated properly and all equipment was deployed. Working methods for segregation of contaminated material from the soil were determined. Besides, risk evaluation was carried out. Pathways between the contaminated soil and people were taken into account. Groundwater samples were taken and analyzed. According to these results, evacuation, area isolation or changing land use options were evaluated. Isolation of the site and removal of radioactive materials were determined as appropriate actions. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2015

How Web-based GIS was used in waste disposal option discussions to develop a better recommendation - 15421

Arriving at a consensus from individuals or parties who look at the world from varying perspectives often involves compromises. For the Paducah Gaseous Diffusion (PGDP) site, the need to compromise has become readily apparent when trying to look at the big picture from the viewpoint of a project engineer, Department of Energy (DOE) official, politician, public citizen, economic development official, or environmental regulator to name a few. Each interested party has its own wishes and desires as it pertains to a particular outcome for a project, area, or the overall site end-state vision. The Paducah Citizens Advisory Board (CAB) is using Geographic Information Systems (GIS) as a tool to help illustrate the intricacies of the PGDP site. This picture allows all parties the opportunity see how DOE Environmental Management (EM) cleanup decisions will affect the greater community by defining the spatial context of the issue in which all parties are interested. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2016

Migration Rates of Some Cations in Unsaturated Layer around the Near-Surface Disposal Facilities of Radioactive Wastes - 16116

In the porous layer around the near-surface underground, the intermittent recharge process of rainwater forms a layer perfectly not saturated with liquid phase. Here, such a layer is simply called 'unsaturated layer'. In this study, the retardation effects of radionuclide migration were examined under an unsaturated condition by using a column packed with silica sand particles. As tracer ions, sodium (Na), europium (Eu) and cesium (Cs) were selected for estimating the retardation effects under both the saturated and unsaturated condition. Particularly, Cs is one of the key elements included in the contaminated soil due to Fukushima Daiichi Nuclear Power Plant Accident. These tracer ions were injected into column with the condition of constant flow rate or constant pressure flow. To quantify the influence of the unsaturated condition on the migration of radionuclides, retardation coefficient (R{sub d}) and Peclet number (P{sub e}) were estimated by applying advection diffusion equation to the experimental results. As a result, the conflicting effects on the retardation effect in the unsaturated layer were suggested; one is the decrease in the retardation effect by interrupting the sorption of ions with gas phase, the other is the increase in the retardation effect by the clogging with gas phase in flow paths. For the assessment of the radionuclide migration in the unsaturated layer, it is important to clarify such complicated behaviors with considering key parameters related to the migration of ions. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2016

Applicability of Wireless Power Transfer for Monitoring Technology of Radioactive Waste Geological Disposal - 16156

To assure the engineered barrier of a high-level radioactive waste repository functions correctly, long-term monitoring inside the backfilled deposition holes and tunnels is planned. Cables are used to power monitoring equipment and send signals however complete isolation will not be possible. Previously developed monitoring systems send information wirelessly and used batteries. Due to the limited battery life, these systems cannot be used for long-term monitoring. In this paper a wireless power transfer method based on magnetic resonant coupling is presented. The necessary transmitter and receiver coils have been developed. The performance of the individual coils has been tested. The performance of the system of transmitter and receiver with both air and bentonite as medium was tested. The results showed that the system with bentonite performed similarly well as the system with air. Wireless power transfer based on magnetic resonant coupling is therefore a feasible method for high-level radioactive waste repository monitoring applications which could in principle work for a period of 100 year or longer. (authors)

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

Geomechanical risk assessment for subsurface fluid disposal operations

Numerical models are commonly used to estimate the state of stress in the subsurface for various engineering applications. These estimates are subject to considerable uncertainty, and yet, the estimates are almost always deterministic, yielding no information about the certainty of the prediction. For some applications, unquantified uncertainties in stress are often acceptable, because the risks related to geomechanics may be of low relative importance compared to other risks (e.g. recoverable resource volume), for which uncertainties are often quantified. Furthermore, many geomechanics-related risks in the petroleum industry are relatively short lived (e.g. well bore stability), and decrease in importance with time. In contrast, for waste water injection or geologic carbon sequestration (GCS), geomechanics-related risks (e.g. seal integrity, induced seismicity) are on par with resource-related risks and are of long-term concern, with the risk generally increasing in importance for a significant period of time. For these reasons, the deterministic stress estimation and risk analysis approaches generally applied in the petroleum industry are insufficient for GCS applications. This paper describes a Bayesian approach to geomechanical uncertainty quantification and risk assessment. The method is demonstrated using data from an active enhanced oil recover/geologic carbon sequestration field as a case study

Burghardt, Jeffrey A.↗
DOE OSTI2025

Coupled Thermo-Hydrological-Mechanical-Chemical Behavior of Anisotropic Granite for Geologic Disposal of High-Level Radioactive Waste: A Core-Scale Laboratory Investigation

The coupled thermo-hydrological-mechanical-chemical (THMC) behavior of rock within an Excavation Damaged Zone (EDZ) is critical for the safety and long-term performance of a geological repository for high-level radioactive wastes. While many laboratory experiments have been conducted to investigate EDZ rocks, the flow and deformation characteristics resulting from anisotropic rock textures and microcrack distribution under triaxial loading and elevated temperatures remain poorly understood. Particularly, cracks at various scales serve as fast paths for fluid flow and solute transport and present as focal points of mechanical weakness, which complicate the coupled THMC processes in anisotropic EDZ rocks and challenge modeling predictions. Here, in this study, a series of core-scale experiments was conducted on three granite samples under repository-relevant conditions. These rock samples were obtained from the Grimsel Underground Research Laboratory (URL), featured by anisotropic minerals (represented by bedding layers) and microcrack distributions and coarse cm-scale grain sizes. During the experiments, samples were subjected to an elevated temperature at 90 °C and different triaxial loading conditions either by radial (normal to bedding layers) or axial (parallel to bedding layers) compaction. Water was injected into the samples, and the rock permeability evolutions and effluent water chemistry were monitored closely. For intact samples, thermal expansion of minerals at 90 °C resulted in a large, 75% irreversible permeability reduction and rock strengthening under radial compaction, while thermal impact was limited to a 15% permeability reduction under axial compaction. In contrast, for a sample containing open cracks, the growth of fractures during the experiment resulted in an abrupt permeability increase and fast failure at 90 °C. The effluent water chemistry indicates much more considerable mineral dissolution from large shear sliding than that in rocks dominated by mechanical compaction. These results helped better understand the coupled THMC processes in anisotropic rocks containing cracks, evaluate the behaviors of EDZ rocks, and predict the long-term evolution of EDZ for the performance of the repositories.

Coupled THMC processes↗
DOE OSTI2017

Radwaste Self-Disposal in Geological Formations by Direct γ-Ray Heating of Rock

The mechanism of direct heating of rock by radiation in order to transfer energy to the surrounding rock in penetration setups that use the heat released in radioactive decay is examined. The spatial distribution of the energy release owing to absorption of {sup 60}Co gamma rays in a layer of soil, salt, and ice is obtained. The temperature distribution and penetration rate are estimated for a {sup 60}Co based setup.

07 ISOTOPE AND RADIATION SOURCES↗