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At least 883 records · Page 49
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

NEVADA NATIONAL SECURITY SITE 2020 DATA REPORT- GROUNDWATER MONITORING PROGRAM AREA 5 RADIOACTIVE WASTE MANAGEMENT SITE

This report presents groundwater and leachate sample results from the Area 5 Radioactive Waste Management Site (RWMS) at the Nevada National Security Site in Nye County, Nevada. Since 1993, groundwater samples have been collected and static groundwater depths have been measured from the aquifer immediately below the Area 5 RWMS. The data are evaluated for evidence of effects on the aquifer related to the Area 5 RWMS. Leachate from the Cell 18 lined mixed waste cell has been sampled since 2011, and leachate from the Cell 25 lined mixed waste cell was first sampled in 2019 after it began receiving waste in August 2018. Leachate data are analyzed for hazardous contaminants to determine appropriate leachate handling and disposal. This report includes five years of data from 2016 through 2020.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2022

NEVADA NATIONAL SECURITY SITE 2021 WASTE MANAGEMENT MONITORING REPORT AREA 3 AND AREA 5 RADIOACTIVE WASTE MANAGEMENT SITES

Environmental monitoring data are collected at and around the Area 3 and Area 5 Radioactive Waste Management Sites (RWMSs) within the Nevada National Security Site (NNSS). This report summarizes the 2021 environmental data to provide an overall evaluation of RWMS performance and to support environmental compliance and performance assessment (PA) activities.

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

Development and Testing of Techniques for In-Ground Stabilization, Size Reduction and Safe Removal of Radioactive Wastes Stored in Large Containments in Burial Grounds - 13591

Radioactive waste materials, including Transuranic (TRU) wastes from laboratories have been stored below ground in large containments at a number of sites in the US DOE Complex, and at nuclear sites in Europe. These containments are generally referred to as caissons or shafts. The containments are in a range of sizes and depths below grade. The caissons at the DOE's Hanford site are cylindrical, of the order of 2,500 mm in diameter, 3,050 mm in height and are buried about 6,000 mm below grade. One type of caisson is made out of corrugated pipe, whereas others are made of concrete with standard re-bar. However, the larger shafts in the UK are of the order of 4,600 mm in diameter, 53,500 mm deep, and 12,000 below grade. This paper describes the R and D work and testing activities performed to date to evaluate the concept of in-ground size reduction and stabilization of the contents of large containments similar to those at Hanford. In practice, the height of the Test Facility provided for a test cell that was approximately 22' deep. That prevented a 'full scale mockup' test in the sense that the Hanford Caisson configuration would be an identical replication. Therefore, the project was conducted in two phases. The first phase tested a simulated Caisson with surrogate contents, and part of a Chute section, and the second phase tested a full chute section. These tests were performed at VJ Technologies Test Facility located in East Haven, CT, as part of the Proof of Design Concept program for studying the feasibility of an in-situ grout/grind/mix/stabilize technology for the remediation of four caissons at the 618-11 Burial Ground at US Department of Energy Hanford Site. The test site was constructed such that multiple testing areas were provided for the evaluation of various tools, equipment and procedures under conditions that simulated the Hanford site, with representative soils and layout dimensions. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
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 OSTI2012

International Perspective on the Application of Non-Destructive Assay Technology Platforms for Sentencing and Disposal of Radioactive Waste - 12113

Over the past decade, major technology improvements have been introduced in the field of Non-Destructive Assay (NDA) for the management and disposal of radioactive waste in compliance with an evolving regulatory structure. For example in the United States, various NDA technologies have been successfully developed to meet the stringent characterization requirements of the Department of Energy. The use of this instrumentation, combined with the compliant operational processes and expertise levels that have emerged in parallel, have enabled over 75,000 m{sup 3} (or in excess of 145,000 containers) of contact and remote handled transuranic (TRU) waste to be sentenced to date to the Waste Isolation Pilot Plant from 10 different consignor sites. Many of these techniques have applicability that transcends national borders and can be used for common characterization challenges in waste sentencing and disposal on an international basis. Applicable waste streams could include LLW, ILW, TRU and HLW. There are specific design aspects of assay equipment that must be tailored to meet the applicable regulatory requirements for detection and quantification of a set of nuclides of interest to a prescribed limit of detection and measurement uncertainty. Each host nation will have specific challenges in the form of matrix types and processes, availability of historical information, needs for portable versus fixed instruments and the requirement to measure all containers versus assay of a representative sample. Furthermore, the practice of load management (combining smaller packages into a larger package designed to meet the overall waste acceptance criteria for the bulk container) may not have universal acceptability. An evaluation has been performed on a sample of the most successful technologies that have recently emerged to understand their applicability in other countries. Two types of instrumentation 'suite' are considered for measurements on drums and larger boxes / crates: (i) High Efficiency Neutron Coincidence counting combined with gamma isotopic analysis (e.g. the SuperHENC), and (ii) Portable NDA using neutron slab counters and far field high resolution gamma spectroscopy. Target countries (outside the United States) for these applications are: China, Japan, UK, Sweden and Canada. Specific challenges in each country are addressed and the applicability of the technologies as 'universal platforms' is considered. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2012

Radiation and Electromagnetic Induction Data Fusion for Detection of Buried Radioactive Metal Waste - 12282

At the United States Army's test sites, fired penetrators made of Depleted Uranium (DU) have been buried under ground and become hazardous waste. Previously, we developed techniques for detecting buried radioactive targets. We also developed approaches for locating buried paramagnetic metal objects by utilizing the electromagnetic induction (EMI) sensor data. In this paper, we apply data fusion techniques to combine results from both the radiation detection and the EMI detection, so that we can further distinguish among DU penetrators, DU oxide, and non- DU metal debris. We develop a two-step fusion approach for the task, and test it with survey data collected on simulation targets. In this work, we explored radiation and EMI data fusion for detecting DU, oxides, and non-DU metals. We developed a two-step fusion approach based on majority voting and a set of decision rules. With this approach, we fuse results from radiation detection based on the RX algorithm and EMI detection based on a 3-step analysis. Our fusion approach has been tested successfully with data collected on simulation targets. In the future, we will need to further verify the effectiveness of this fusion approach with field data. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
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↗