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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 739 records · Page 41
All sourcesNASA NTRSDOE OSTI
DOE OSTI2013

Distribution of Radioactive Materials in the Absheron Peninsula, Azerbaijan - 13567

The Absheron Peninsula forms the extreme Eastern part of Azerbaijan and juts into the Caspian Sea. The region has a long history of oil and gas exploration, transport, and processing and includes a number of abandoned chemical plants that were used in the separation of iodine from formation waters. As a result of lax environmental standards during the Soviet era, the industrial activity has led to serious contamination from oils residues, heavy metals and naturally occurring radioactive materials (NORM). Radiometric surveys performed over a wide range of the Absheron Peninsula showed generally low NORM concentrations. However, radiation levels two to three orders of magnitude above background levels were detected at two abandoned iodine separation plants near the capital city, Baku. These elevated radiation levels are mainly due to Ra-226 and U-238 with lower contributions from Ra-228 and U-235. (authors)

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2015

Equipment for the continuous measurement and identification of gamma radioactivity on aerosols

Presentation the Equipment for the Continuous Measurement and Identification of Gamma Radioactivity on Aerosols developed by the Nuclear Engineering Research Group (NERG) from the Technical University of Catalonia (UPC) and the Raditel Company. The device is based on a fixed filter of glass fiber (100% borosilicate), this allows determine the concentration of activity of gamma emitters on aerosols in air. A specifically developed Spectrometry Analysis System has been developed. The analysis of the spectra allows the identification of the emitters and determine the concentration of activity. Nowadays four Stations with this equipment are operating on the Environmental Radiological Surveillance Network of the Catalonian Generalitat (Spain): two near the Asco and Vandellos Nuclear Power Plants in the province of Tarragona and one in the city of Barcelona. Soon a fourth monitor will be incorporated at Roses (province of Girona) and a fifth in Puigcerda (province of Barcelona). We present measurements and analysis of the evolution of the emitters identified on different stations of the Network. (authors)

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗
DOE OSTI2016

Apatite Based Ceramic Waste Forms for Immobilization of Radioactive Iodine, An Overview - 16155

Apatite based ceramic waste forms are the most promising candidates for immobilization of radioactive iodine (I-129). While lead-vanadium based apatites have been studied for a long time, significant progress has been made in recent years in the domain of calcium-phosphate based apatites for iodine immobilization. This article is an attempt to present an overview of the progress that has been made in terms of developing novel synthesis and processing routes to contain iodine in apatite based ceramic waste forms. The challenges associated with current state-of-the art waste form synthesis techniques along with novel routes to synthesize these waste forms at low temperatures have also been discussed. (authors)

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

Protecting the Columbia River through Removal and Packaging of Radioactive Sludge in Hanford's K Area - 16572

The Columbia River once provided power and cooling water to operations on the Hanford Site; today, more than a million people downstream from Hanford rely on the river for agriculture, fishing and recreation. The Department of Energy and contractor CH2M HILL Plateau Remediation Company (CH2M) is making significant progress in protecting that vital resource. Eight of nine reactors along the river have been cocooned and soil and groundwater remediation is successfully reducing the concentration of contaminants in groundwater. The 100-K area is the last area where significant work remains to protect the river. CH2M has accomplished much in the past ten years, including demolishing the K East reactor fuel storage basin in 2009. Prior to demolition of the basin, highly radioactive sludge from that basin was transferred into containers located in the nearby K West reactor fuel storage basin. Today, the K East reactor is in interim surveillance mode, and work is underway in the K West basin to remove the sludge, which is a mixture of tiny fuel corrosion particles, fuel rod and metal fragments and soil and sand less than 1/4-inch in diameter. CH2M has designed a sludge removal system that will safely and efficiently remove the sludge from the K West basin and deposit it into specially designed containers which will be relocated to a storage facility on Hanford's Central Plateau. Procurement, fabrication and delivery of the sludge removal system is underway, with extensive testing and training planned for 2016 and 2017 ahead of the goal of removing sludge from the river by September 30, 2018. This project must account for many technical and safety considerations that render the project very challenging. Several safety measures have been incorporated as a result of safety evaluations. This paper will describe the issues facing the project team in developing the safety basis requirements and incorporating them into the design of the process equipment and construction of the facility to house the repackaging operations. This paper will allow CH2M and DOE-RL to share lessons learned and progress to date with other complex and hazardous projects across the DOE complex. (authors)

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

Final Surrender of Radioactive Substances (Environmental) Permits on UK Nuclear Licensed Sites - 16646

This paper is split into three, linked, parts; each part explains work being taken forward by the United Kingdom (UK) Government and/or the nuclear site regulators to apply proportionate regulatory controls before, during and after nuclear site decommissioning and clean-up. Part I of the paper describes work led by UK Government to examine credible options for a step-wise removal of those safety, security and environmental protection regulations that apply to nuclear site decommissioning and clean-up. Any removal of regulations will have to take due account of and be proportionate to the residual risk following cessation of all clean-up works. Part II of the paper describes the approach used by the UK Environment Agencies to regulate final site clean-up of UK nuclear licensed sites. Ultimately, clean-up will result in nuclear sites being released from radioactive substances regulation. Part III of the paper links Parts I and II of the paper together by describing how the UK Environment Agencies will apply proportionate regulation to the clean-up of the 140-acre Dounreay site in Caithness which is the largest nuclear clean-up project in Scotland and the second largest in the UK, after Sellafield. (authors)

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

Methodology for Volume Reduction of Radioactive Metallic Waste - 19491

A decontamination methodology for out-of-core nuclear reactor alloys is being developed to reduce the volume of low- and intermediate-level radioactive metallic wastes. For out-of-core reactor metals contamination is limited to surface oxides. For surface oxide removal a technology based on laser ablation is being explored. This paper presents work performed to identify the key parameters that affect the efficiency of removal of surface oxides from out-of-core reactor metals and alloys. This study examined carbon steel (used for coolant feeder pipes of CANDU{sup R} reactors) as a model reactor material. The morphology and thickness of oxides on a used feeder pipe vary considerably depending on its service life and the location along the pipe. Hence, oxides with different morphologies and thicknesses were first grown by corroding carbon steel coupons under different solution conditions. The oxides formed ranged from thin layers of uniformly distributed mixed Fe{sup II}/Fe{sup III} hydroxides/oxides to dual layers consisting of ferric oxide/oxyhydroxide islands with thickness up to 200 μm on top of the more uniformly distributed mixed Fe{sup II}/Fe{sup III} layer. Removal of these oxides was performed using a 1064 nm pulsed laser. Of the laser parameters tested, the pulse radiance was found to be the most important. Four radiances ranging from 5 to 200 MW/cm{sup 2} were used. At radiances higher than 100 MW/cm{sup 2}, single pulses were sufficient to remove both types of oxides, but also extensively melted the metal substrate. At lower radiances, multiple pulses were required to remove the oxides completely, but caused less damage to the metal substrate. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
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 OSTI2022

Carrier gas attenuation in gamma assay of radioactive xenon samples

Gamma attenuation attributable to xenon and carbon dioxide carrier gas in radioactive xenon assay samples has been calculated using Monte Carlo n-Particle (MCNP) transport code for the 0.65 mL flame sealed ampoule (bean), and 15 mL and 50 mL Schlenk tube geometries. The attenuation was correlated as a % loss per standard mL of carrier gas. In this work, high Purity Ge gamma spectroscopy experiments were performed to measure against the MCNP results. The experimental results from the 133 Xe in xenon carrier gas in a bean geometry showed 0.97 ± 0.4% loss per standard mL xenon, which was in agreement with the MCNP predictions.

98 NUCLEAR DISARMAMENT, SAFEGUARDS, AND PHYSICAL P↗
DOE OSTI2025

Mercury sequestration in alkaline salt low-level radioactive waste

Liquid low-level radioactive waste at the Savannah River Site contains several species of mercury, including inorganic, elemental and methylmercury. This waste is solidified and stabilized in a cementitious waste form referred to as saltstone. Soluble mercury is stabilized as β-cinnabar, HgS as the result of reaction between the mercury and sulfur present in blast furnace slag, one of the cementitious regents. In this investigation, Mersorb®, a commercial granular activated carbon impregnated with sulfur, was evaluated as a pretreatment to remove mercury from the solution prior to cementation. Mersorb® was found to remove more than 96 mass percent of the methylmercury in simulated tank waste solution when the mass ratio of Mersorb® to mercury was above 2.5. Slag sequestered relatively more inorganic mercury than organic mercury in simulated tank waste after 24 hours of contact. This is likely due to the mercury-carbon bond being more covalent than the mercury-oxygen bond and therefore more difficult to break and slower to form HgS.

Cementitious Material↗
DOE OSTI2025

Eddy covariance towers as sentinels of abnormal radioactive material releases

Ensuring accurate detection and attribution of abnormal releases of radioactive material is critical for protecting human health and safety. Most commonly, such detection is accomplished via active monitoring approaches involving the collection of physical samples. Further, this is labor intensive and limits the temporal and spatial resolution of any detected events to a relatively coarse level. As an alternative first step towards passive monitoring, we developed an approach using eddy flux tower data records to identify signals from a known abnormal release and quantify the extent to which that signal also occurs at other times in the data record. Through two case studies, one of which targeted the Fukushima nuclear disaster and the other targeting an abnormal release event at a radioisotope production facility in Fleurus, Belgium, we tested our approach and identified several potential heretofore unidentified abnormal events that were consistent with atmospheric circulation patterns and/or wind direction from known release sites. Because our approach is relatively simple and is resistant to systematic errors in the observational record, it has broad applicability beyond specific constituents and ecosystem types to identify a wide variety of limited-duration anomalies in flux tower data to ensure human health and industrial safety.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2022

Experimental validation of the mechanistic scale-up methodology of gas–solid spouted beds using radioactive particle tracking (RPT)

The very high-temperature reactors (VHTRs) are highly ranked among candidates of Generation IV of nuclear reactors due to their high efficiency, safety, the resistance to proliferation, and reliability. The VHTRs are preferentially fueled by Tristructural-isometric (TRISO) coated fuel particles which has fuel kernels of fissile material coated by four coating layers: a porous buffer pyrolysis carbon layer (buffer PyC), an inner dense pyrolysis carbon layer (IPyC), a silicon carbide layer (SiC) and an outer dense pyrolysis carbon layer (OPyC). The heart of the operation and safety of the VHTRs significantly depends on the reliability of the coating layers of TRISO particles to retain metallic and gaseous fission products within the particles. The technique used for coating TRISO particles are gas-solids spouted beds via chemical vapor deposition (CVD). Fabrication of high-quality low-defect TRISO fuel particles fuel at larger scale spouted beds is required to support the commercialization of the VHTRs. In this work, our new developed mechanistic scale-up methodology of gas-solids spouted beds based on matching the radial profile of gas-holdup has been demonstrated and validated using radioactive particle tracking (RPT). Two spouted beds of small and larger scales were used in the study. Three sets of conditions were carried out which include the conditions of the reference case in the large scale, conditions that provide similar gas holdup radial profile to that of the reference case and conditions that provided dissimilar gas holdup radial in the small-scale spouted beds. The results confirm the validation of the scale-up methodology in terms of the dimensionless values of the spout diameter, cumulative probability distribution of the solids particles penetration into the spout, fraction of cycle time in each region of the bed, the radial profiles of the dimensionless values of the root-mean-square particle velocities and solids eddy diffusivity. Finally, the results further advance the knowledge and understanding of the gas-solids spouted beds provide deeper insight into their solids dynamics and presenting important benchmarking data for validating computational fluid dynamics codes and models. At last, procedures are established for the implementation of the new scale-up methodology.

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗
DOE OSTI2021

Chemical degradation of fly ash blended concrete with the seasonal variation of rainwater in a radioactive waste repository: A thermodynamic modeling approach

Highlights: • The thermodynamic model for the cementitious system was successfully developed. • The chemical degradation of concrete was greatly affected by rainwater types. • Inorganic carbon species in rainwater reduced the chemical resistance of concrete. • The durability of concrete to rainwater decreased with increasing fly ash content. This study presents a long-term degradation behavior of fly ash blended concrete in a vault type low- and intermediate-level radioactive waste (LILW) repository by thermodynamic equilibrium calculations using PHREEQC combined with CEMDATA18 database. Since rainwater plays a predominant role as leachate for the concrete waste container in the repository, the effect of chemical properties of seasonal rainwater on the chemical degradation of concrete was analyzed. In addition, the impact of the blending with fly ash on the chemical degradation was evaluated through a gradual replacement of ordinary Portland cement (OPC) by fly ash. Regardless of the replacement level, autumn rainwater showed the greatest influence on the concrete degradation owing to the presence of inorganic carbon species, which induce the carbonation. The resistance of concrete to chemical degradation by rainwater was persistently reduced due to the decreasing formation of portlandite and calcium silicate hydrate (C-S-H) with increasing replacement level.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Recent seawater intrusion into deep aquifer determined by the radioactive noble-gas isotopes 81 Kr and 39 Ar

Radioactive noble-gas isotopes tracers 81 Kr and 39 Ar are used for the first time to measure the residence times of deep (~1000 m) saline coastal groundwater, and to determine its connection mode with the sea. The average rate of seawater intrusion into the deep aquifer in Israel, located near the Mediterranean Sea, is estimated. 81 Kr-ages of the saline water samples, found to be younger than 40 ka, contradict previously estimated ages of up to several million years based on hydrogeological considerations. The new results imply a stronger and more recent connection between the aquifer and the sea, and indicate that the intrusion occurred during the sea-level rise that began about 20 ka ago. These coastal aquifers need to be managed with caution because lowering of the adjacent fresh water level due to over pumping could accelerate seawater intrusion in a relatively short time. As a result, this study demonstrates the suitability of these two noble-gas tracers for the examination of hydrogeological systems in general and for the study of seawater intrusion in particular.

39Ar↗
DOE OSTI2016

An advanced evaluation of spouted beds scale-up for coating TRISO nuclear fuel particles using Radioactive Particle Tracking (RPT)

A set of dimensionless groups has been proposed in the literature by He et al. (1997) to scale-up gas-solid spouted beds while maintaining their hydrodynamics similarity. The literature reported studies do not provide conclusive assessments about this methodology. Therefore, in this work, we have applied an advanced non-invasive Radioactive Particle Tracking (RPT) technique for the first time to evaluate such scale-up methodology by measuring the local solids velocity, normal and shear stresses and the turbulent kinetic energy. The axial and azimuthal averaged radial profiles of solids velocity, normal stresses, shear stresses, and turbulent kinetic energy illustrate that the similarity of the hydrodynamics has not been attained when the proposed set of dimensionless groups has been matched using two sizes of spouted beds of 0.076 m and 0.152 m and sets of operating conditions. The conclusion is consistent with the recent reported findings by measuring cross sectional distribution and radial profiles of solids and gas holdups along the bed height using gamma-ray computed tomography and by the limited point measurements of solids velocity and holdup using optical fiber probe. It is clear that local measurements of hydrodynamic parameters are essential for detailed assessment of scale-up methodologies. Here, the presented results of our work in terms of the components profiles of the particles radial velocities and turbulent parameters are also valuable for benchmarking computational fluid dynamics codes and models.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2015

Atmospheric plume progression as a function of time and distance from the release point for radioactive isotopes

The International Monitoring System contains up to 80 stations around the world that have aerosol and xenon monitoring systems designed to detect releases of radioactive materials to the atmosphere from nuclear tests. A rule of thumb description of plume concentration and duration versus time and distance from the release point is useful when designing and deploying new sample collection systems. This paper uses plume development from atmospheric transport modeling to provide a power-law rule describing atmospheric dilution factors as a function of distance from the release point.

atmospheric plume progression↗
DOE OSTI2017

Removal of Chalk River unidentified deposit (CRUD) radioactive waste by enhanced electrokinetic process

Decontamination techniques proposed and used to remove Chalk River unidentified deposit (CRUD) in radioactive waste management. In cases of huge volumes of metal or radionuclides contaminated by CRUD, removal of CRUD by mechanical or chemical decontamination is difficult. An advanced electrokinetic process combined with chemical decontamination was applied to remove CRUD and experimentally evaluated. We used oxalic acid for CRUD removal, and cobalt (Co) released from the CRUD was transferred to the cathode in an electrokinetic reactor. Our results indicate that the combined system is efficient for CRUD removal with enhanced, efficiency by use of the cation exchange membrane and zeolite.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2019

The radioactive source calibration system of the PROSPECT reactor antineutrino detector

The Precision Reactor Oscillation and Spectrum (PROSPECT) Experiment is a reactor neutrino experiment created to search for sterile neutrinos with a mass on the order of 1 eV/c 2 and to measure the spectrum of electron antineutrinos from a highly-enriched 235 U nuclear reactor. The PROSPECT detector consists of an 11 by 14 array of optical segments in 6 Li-loaded liquid scintillator at the High Flux Isotope Reactor in Oak Ridge National Laboratory. Antineutrino events are identified via inverse beta decay and read out by photomultiplier tubes located at the ends of each segment. The detector response is characterized using a radioactive source calibration system. Here, we describe the design, operation, and performance of the PROSPECT source calibration system.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2017

An advanced evaluation of the mechanistic scale-up methodology of gas–solid spouted beds using radioactive particle tracking

For this work, we implemented for the first time our radioactive particle tracking as an advanced noninvasive technique to further evaluate and validate our newly developed mechanistic scale-up methodology based on matching the radial profile of the gas holdup. Two spouted beds with diameters of 0.076 and 0.152 m were used. Three sets of conditions were implemented; i.e., conditions of the reference case, conditions that provided a gas-holdup radial profile similar to that of the reference case, and conditions that provided a gas-holdup radial profile dissimilar to that of the reference case. The results confirm the validation of the scale-up methodology in terms of obtaining closer dimensionless values and radial profiles of components of the particle velocity, normal stress, shear stress, and turbulent kinetic energy. The results further advance the understanding of gas–solids spouted beds, provide deeper insight into the solids dynamics of the beds and present important benchmarking data for validating computational fluid dynamics codes and models.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗