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Effect of Radiation from Low-Level Radioactive Waste Leachate on Antioxidant Depletion in HDPE Geo-membrane - 16087

Low-level radioactive waste (LLW) and mixed waste (MW) disposal facilities in the US are required to have a service life in excess of 1000 yr. Understanding the rate of degradation of high-density polyethylene (HDPE) geo-membranes (GMs) used in LLW and MW facilities is necessary to assess their service life when conducting a performance assessment for a disposal facility. In LLW and MW disposal facilities, GMs may be exposed to radionuclides that may accelerate antioxidant depletion and degradation. This paper evaluates how radiation dosage affects antioxidant depletion in HDPE GMs and makes inferences regarding the impact of radiation on GM service life. Specimens of 0.04-mm-, 0.1-mm-, and 2-mm-thick HDPE GMs were exposed to a sealed source of Am-241 to simulate alpha radiation from LLW leachate (e.g., uranium). The specimens were exposed to the sealed source for 1-50 h, followed by oxidative induction time (OIT) testing to determine depletion of antioxidants in response to exposure. Penetration of alpha particles in the HDPE GM exposed to the sealed source was evaluated with the program Geometry And Tracking (GEANT4). The GEANT4 modeling indicates that physical dose deposition for alpha particles largely occurs on the superficial layers and decreased monotonically with depth to a negligible dose (∼ 28 μm). For a 2-mm-thick HDPE GM, there was no change in OIT after exposure, whereas in much thinner GMs (e.g., 0.04 mm), significant antioxidant depletion occurred after exposure, reflecting the shallow penetration of alpha radiation at the surface of HDPE GM. (authors)

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2016 Annual Summary Report for the Area 3 and Area 5 Radioactive Waste Management Sites at the Nevada National Security Site, Nye County, Nevada: Review of the Performance Assessments and Composite Analyses

The Maintenance Plan for the Performance Assessments and Composite Analyses for the Area 3 and Area 5 Radioactive Waste Management Sites at the Nevada Test Site (National Security Technologies, LLC 2007a) requires an annual review to assess the adequacy of the performance assessments (PAs) and composite analyses (CAs), with the results submitted to the U.S. Department of Energy (DOE) Office of Environmental Management. The Disposal Authorization Statements for the Area 3 and Area 5 Radioactive Waste Management Sites (RWMSs) also require that such reviews be made and that secondary or minor unresolved issues be tracked and addressed as part of the maintenance plan.The U.S. Department of Energy, National Nuclear Security Administration Nevada Field Office (NNSA/NFO) performed an annual review of the Area 3 and Area 5 RWMS PAs and CAs for federal fiscal year (FY) 2016. This annual summary report presents results and conclusions of the FY 2016 review, and determines the adequacy of the PAs and CAs. Operational factors (e.g., waste forms and containers, facility design, and waste receipts), closure plans, monitoring results, and research and development (R&D) activities were reviewed to determine the adequacy of the PAs. Likewise, the environmental restoration activities at the Nevada National Security Site (NNSS) relevant to the sources of residual radioactive material that are considered in the CAs, the land-use planning, and the results of the environmental monitoring and R&D activities were reviewed to determine the adequacy of the CAs. Important developments in FY 2016 include the following: Development of a new Area 5 RWMS closure inventory estimate based on disposals through FY 2016, Evaluation of new or revised waste streams by special analysis, and Development and acceptance of version 4.200 of the Area 5 RWMS GoldSim PA/CA model. The Area 3 RWMS has been in inactive status since July 1, 2006, with the last shipment received in April 2006. The FY 2016 review of operations, facility design, closure plans, monitoring results, and R&D results for the Area 3 RWMS indicates no changes that would impact PA validity. The conclusion of the annual review is that all performance objectives can be met and the Area 3 RWMS PA remains valid. There is no need to revise the Area 3 RWMS PA. Review of Area 5 RWMS operations, design, closure plans, monitoring results, and R&D activities indicates that no significant changes have occurred. The FY 2016 PA results, generated with the Area 5 RWMS v4.200 GoldSim PA model, indicate that there continues to be a reasonable expectation of meeting all performance objectives. All results remain less than 50% of their performance objectives. The results and conclusions of the Area 5 RWMS PA are judged valid, and there is no need to the revise the PA. A review of changes potentially impacting the CAs indicates that no significant changes occurred in FY 2016. A new Corrective Action Unit (CAU), CAU 576, with corrective action sites near the Area 3 RWMS and Area 5 RWMS was identified in FY 2016. The sites are currently under investigation and not expected to be important sources for the CA. The continuing adequacy of the CAs was evaluated with the new models, and no significant changes that would alter the CAs’ results or conclusions were found. The revision of the Area 3 RWMS CA, which will include the Yucca Flat Underground Test Area (CAU 97) source, is scheduled for FY 2024, following the completion of the Corrective Action Decision Document/Corrective Action Plan. Inclusion of the Frenchman Flat Underground Test Area (CAU 98) source in the Area 5 RWMS CA is planned pending the completion of the CAU 98 Closure Report in FY 2017. Near-term R&D efforts will focus on continuing development of the PA, CA, and inventory models for the Area 3 and Area 5 RWMSs.

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NCRP Program Area Committee 5: Environmental Radiation and Radioactive Waste Issues

Program Area Committee 5 of the National Council on Radiation Protection and Measurements (NCRP) focuses its activities on environmental radiation and radioactive waste issues. Historically this Committee addressed emerging issues of the nation pertaining to radioactivity or radiation in the environment or radioactive waste issues due either to natural origins or to manmade activities. The Committee continues to identify such issues in the future.

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Conditioning of Pu-containing radioactive waste generated in the Hot-lab: where are we now - 15400

To achieve an optimal strategy for interim storage and final disposal, solid radioactive waste has to be sorted and treated. This strategy is based on the requirement to reduce the volume of waste designated for long term disposal, mainly for economical and safety reasons. In addition, the radiological limitations for shipping of the waste packages to a disposal site have to be taken into account as well as the improved regulatory requirements for material under IAEA control. In case of the operational Pu-contaminated and -containing waste from the PSI-Hot laboratory in Switzerland, the existing and over years practiced conditioning method needed improvement. The existing authorized specifications of the conditioning process had to be revised for an optimization of the interim-storage and the deep geological disposal. This was done by the PSI Section for Dismantling and Waste Management. The improvement focused on technical aspects as well as improvement of the documentation for the certification by final depositor (Nagra) and the safety authority (ENSI). This work started in 2008. In 2012 ENSI issued an authorization to realize the first conditioning according the new specification, formally as a certification test ('Type Test') prior to final approval by the ENSI. But, although a licensed method by the competent authority is available, modifications could be necessary and new tasks come up. In 2013 the PSI has produced 13 waste-packages as a Type Test. To obtain the legal authorization ('Type Approval'), some open issues ought to be answered. Waste is continuously generated and so the question arises: When will the next conditioning be done and applying which method? (authors)

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Tribal Revegetation Project Final Project Report: 92-Acre Area, Area 5 Radioactive Waste Management Complex, Nevada National Security Site, Nevada

Nuwu (Southern Paiute), Newe (Western Shoshone), and Nuumu (Owens Valley Paiute) are linguistically related, Numic-speaking peoples who are part of the broader Uto-Aztecan language group. Numic peoples view the land as a holistic, living, sentient being with feelings and purpose. The land is personified with human characteristics and it needs to be experienced to be understood through “learning by doing.” Numic peoples do not support ground disturbing activities within their ancestral lands, including activities tied to the storage of low-level radioactive waste or classified materials on the NNSS, which they view as culturally inappropriate. These deep-rooted ancestral connections are the impetus for reinforcing Numic responsibility for healing disturbed areas by integrating respect and patience with consistent Tribal interaction. Tribal Ecological Knowledge (TEK) is the science of describing Tribal approaches for understanding natural resources. Numic TEK is embedded in traditional teachings learned incrementally over time though experience and it evolves through lessons learned and responses to environmental changes over millennia. Therefore, TEK can broaden and enhance Western scientific knowledge associated with revegetation, especially in highly disturbed areas. The project blended TEK with Western scientific ecological methods to create a vegetative cover within test plots on the 92-Acre Area located at the Radioactive Waste Management Complex (RWMC) located in Area 5 on the Nevada National Security Site (NNSS). The vegetated test plots were systematically created for the Department of Energy (DOE) in tandem with the existing Federal Facilities Agreement and Consent Order (FFACO) with the Nevada Department of Environmental Protection (NDEP). Three previous contractor-lead attempts at revegetation, one targeting full cover revegetation and two targeting test plot revegetation, did not achieve the anticipated results at this location. When presented to the 16 American Indian Tribal nations and affiliated groups with cultural and historical ties to the NNSS, the group appointed a Tribal Revegetation Committee (TRC) that included six expert Tribal knowledge holders to collaborate with an ethnoecologist/cultural anthropologist and two biologists. Project design, planning, seed and outplant selection, spiritual land preparation, and methodology were guided by the TRC and an ethnoecologist/cultural anthropologist from Portland State University (PSU) and biologists from Desert Research Institute (DRI). Using TEK, the TRC recommended a specific seed mixture that contained nine native plant species and three species of outplants. The revegetation effort included preparing and planting thirty 10 m × 10 m (32.8 ft × 32.8 ft) seeded plots, twelve of which also included outplants; and eight 10 m × 100 m (32.8 ft × 328 ft) plots that only received outplants, all atop a waste cell cover. The TRC and the project team creatively adapted TEK with Western scientific methods so that the planned revegetation efforts could occur within the safety and security parameters of the RWMC. Test plots were subjected to one of five soil treatments with varying combinations of straw or mulch applications, soil amendment, and/or outplant planting and one of two watering treatments (watered or unwatered). Planting was divided into two events: one in the fall season and another during the subsequent spring season based on TEK and a corresponding recommendation from the TRC. Monitoring and spiritual management was conducted by the TRC to evaluate plant progress on a monthly basis (in conjunction with the biologist and anthropologist) during each respective growing season for a period of three years after planting. This approach allowed Tribal members the opportunity to conduct traditional blessings and other culturally appropriate activities to restore balance to the land in accordance with Tribal protocols. Following TEK-guided methods, successful plant establishment from seed stock and outplants was observed in many plots. Overall, plots planted in the spring, as recommended by the TRC, showed higher rates of outplant survival and native seedling emergence than those planted in the fall. This finding is significant because it is contrary to the original guidance and previous approaches provided for planting in this region. The TRC believes the frequent co-occurrence of native seedlings near surviving outplants indicates an important symbiotic relationship understood by Tribal communities and overlooked by others. Watered outplants displayed much higher survivability than unwatered plants, even after watering was reduced after the plants were established. Soil amendments and mulch created higher densities of native plants from seed. Many native seedlings showed significant delays in germination, which is considered a normal adaptation to desert climates. Some native plants did not germinate until the third growing year, whereas others germinated during the first growing year, which demonstrates the complexity of the desert environment. Evidence of native insects, reptiles, mammals, and birds, as well as native plants that were not part of the planted species, were noted and considered culturally significant. Despite the presence of non-native plants, native outplants continued to thrive and the incidence of native plant germination from seed increased over time. These successful revegetation results where previous efforts were unsuccessful reinforce the importance of integrating regionally appropriate, TEK-guided methodology with Western science to achieve positive results and the necessity of integrating Tribal involvement in all stages of the revegetation effort. Expanded approaches coupled with Tribal knowledge and tools from Western science addressed a complex problem tied to revegetating atop a low-level radioactive waste cell. The level of Tribal participation serves as a progressive model for building collaborative relationships and addressing ecological challenges on the NNSS.

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Improvement of Quantification in Non-Destructive Characterization of Radioactive Waste Packages -Introduction to the Ideas of a Currently Started Project - 20197

For the characterization of radioactive waste packages (e.g. 200-L drums) with inhomogeneous activity and density distributions preferably non-destructive methods like segmented gamma scanning and transmission measurements are applied. While the first is used for identification of the radioactive inventory, both are necessary for a reliable activity quantification. Although at nuclear facilities, segmented gamma scanner are state-of-the-art and are mostly equipped with a vertically moveable transmission source the combining of this data and further a-priori information improving accuracy in data estimation giving realistic, reliable and traceable uncertainty estimations are improvable. This challenge is tackled by a R and D project funded by the German Federal Ministry of Education and Research (BMBF). The boundary conditions for this project are (i) taking into account the typical instrumentation available at nuclear facilities, (ii) minimize the overall measurement time and (iii) combining data from emission and transmission measurements by Bayesian methods. For the R and D project, being still in its initial stage, the basic ideas, the data used for evaluation and the result of a preliminary investigation demonstrating the proof of principle are presented. Additionally, some first aspects on spatial resolution in emission and transmission measurements are addressed. (authors)

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Performance Assessment for the E-Area Low Level Radioactive Waste Disposal Facility at the Savannah River Site: Chapter 1

This report documents the revised Performance Assessment (PA) analysis for the E-Area Low-Level Waste Facility (ELLWF) at the United States (U.S.) Department of Energy (DOE) Savannah River Site (SRS). A PA analysis is required for DOE-operated facilities that dispose of low-level radioactive waste. PA analyses simulate (1) the release of radionuclides from the disposal site after facility closure, (2) transport of those contaminants through the environment, and (3) exposure/impacts to potential receptors. The purpose of the PA analysis is to demonstrate that the facility is operated in a manner that ensures long-term environmental protection after facility closure, thereby providing for the protection of public health and safety in limiting doses to a hypothetical member of the public (MOP) or an inadvertent human intruder (IHI). DOE Manual (M) 435.1-1, Chg. 3, Radioactive Waste Management (U.S. DOE, 2021b) establishes quantitative post-closure environmental impact limits and requires a facility-specific PA analysis to demonstrate compliance with these limits for DOE low-level waste (LLW) disposed of after September 26, 1988. These limits are defined in terms of human health (e.g., dose limits) with respect to radioactive constituents in the waste.

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Fiscal Year 2020 Annual Summary Report for the Area 3 and Area 5 Radioactive Waste Management Sites at the Nevada National Security Site, Nye County, Nevada

U.S. Department of Energy Standard DOE-STD-5002-2017, “Disposal Authorization Statement and Tank Closure Documentation,” requires preparation of an Annual Summary Report comparing low-level radioactive waste disposal facilities operations with the Disposal Authorization Statement (DAS) and its supporting technical documents including the performance assessment (PA) and the composite analysis (CA). The fiscal year (FY) 2020 Annual Summary Report for the Area 3 and Area 5 Radioactive Waste Management Sites (RWMSs) was prepared by reviewing planned and discovered changes, waste receipts, monitoring results, research and development (R&D) results, and the status of DAS conditions and issues to assess the validity of the DASs, PAs, and CAs.

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A Study of a Monitoring Program for Intermediate Depth Disposal of Low- Level Radioactive Waste - 20167

This study investigated a monitoring program for intermediate depth disposal of low-level radioactive waste. At first, it extracted monitoring targets, such as the status of cracks in the low diffusion layer after closure of the facility. Secondly, it focused on distributed optical fiber sensors which can minimize the amount of cable, and measurement positions and methods were specifically determined to propose the monitoring method. Finally, conformity to regulatory requirements was verified to clarify key points and issues to be addressed in performing monitoring. (authors)

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Mitigation of Radioactive Waste by Sampling and Analyzing the Affected Area and Efficient Use of Different Detectors - 17139

The paper describes the ways by which the mitigation of the radioactive waste during events like decommissioning of nuclear plants, mines, other nuclear-related facilities and also in event of nuclear disaster is done, so that the rehabilitation process for flora and fauna can begin in a natural manner. There are many parameters that have to be kept in mind during the planning stage of environmental remediation (ER), as there are many hindrances and snags that might occur during environmental remediation and rescue operation. The paper describes the problems faced during ER operations in the developing countries and needs of international committees. The paper emphasizes proper site characterization and suggestions for it, and suggests simultaneous detection of various activity of radionuclides dispersed and the need for proper knowledge and handling in ER operations. It describes how the radioactivity can be an interference in detection and the importance of low-level activity. The paper describes why site characterization should be quick and prior to other important key points during rescue operations. Also, it gives a description of various detectors used widely and their related significance in ER. The paper describes the strategy on how after site surveying the input can be used to map an area, as to provide easy operation and working conditions for personnel, and how it can be helpful in the evaluation of other parameters. The paper also gives suggestions on the use of bio-indicators in above described events and their benefits. (authors)

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Public Preferences Related to Radioactive Waste Management in the United States: Methodology and Response Reference Report for the 2016 Energy and Environment Survey.

This report presents the questions and responses to a nationwide survey taken June 2016 to track preferences of US residents concerning the environment, energy, and radioactive waste management. A focus of the 2016 survey is public perceptions on different options for managing spent nuclear fuel, including on-site storage, interim storage, deep boreholes, general purpose geologic repositories, and geologic repositories for only defense-related waste. Highlights of the survey results include the following: (1) public attention to the 2011 accident and subsequent cleanup at the Fukushima nuclear facility continues to influence the perceived balance of risk and benefit for nuclear energy; (2) the incident at the Waste Isolation Pilot Plant in 2014 could influence future public support for nuclear waste management; (3) public knowledge about US nuclear waste management policies has remined higher than seen prior to the Fukushima nuclear accident and submittal of the Yucca Mountain application; (6) support for a mined disposal facility is higher than for deep borehole disposal, building one more interim storage facilities, or continued on-site storage of spent nuclear fuel; (7) support for a repository that comingles commercial and defense related waste is higher than for a repository for only defense related waste; (8) the public’s level of trust accorded to the National Academies, university scientists, and local emergency responders is the highest and the level trust accorded to advocacy organizations, public utilities, and local/national press is the lowest; and (9) the public is willing to serve on citizens panels but, in general, will only modestly engage in issues related to radioactive waste management.

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Hanford double-shell tank AY-102 radioactive waste leak investigation update - 15302

Tank AY-102 was the first of 28 double-shell radioactive waste storage tanks constructed at the U.S. Department of Energy's Hanford Site, near Richland, WA. The tank was completed in 1970, and entered service in 1971. In August, 2012, an accumulation of material was discovered at two sites on the floor of the annulus that separates the primary tank from the secondary liner. The material was sampled and determined to originate from the primary tank. This paper summarizes the changes in leak behavior that have occurred during the past two years, inspections to determine the capability of the secondary liner to continue safely containing the leakage, and the initial results of testing to determine the leak mechanism. (authors)

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UNREVIEWED DISPOSAL QUESTION EVALUATION: Disposal of the Princeton Plasma Physics Laboratory Torus Cleanup System Molecular Sieve Dryer Bed at the Area 5 Radioactive Waste Management Site, Nevada National Security Site, Nye County, Nevada

This Unreviewed Disposal Question Evaluation (UDQE) assesses whether the Princeton Plasma Physics Laboratory (PPPL) Torus Cleanup System Molecular Sieve Dryer Bed (MSDB), PERM000000043, Revision 0 (Perma-Fix [PERM] 2021), is suitable for shallow land burial (SLB) at the Area 5 Radioactive Waste Management Site (RWMS) on the Nevada National Security Site (NNSS). Disposal of the PPPL Torus Cleanup System MSDB meets all performance objectives of DOE Manual DOE M 435.1-1, Radioactive Waste Management Manual, Chapter IV, Section P (DOE 1999). The PPPL Torus Cleanup System MSDB waste stream is recommended for acceptance without conditions.

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2014 Annual Summary Report for the Area 3 and Area 5 Radioactive Waste Management Sites at the Nevada National Security Site, Nye County, Nevada: Review of the Performance Assessments and Composite Analyses

This report summarizes the results and conclusions of the annual review of the performance assessments (PAs) and composite analyses (CAs) of the Area 3 and Area 5 Radioactive Waste Management Sites (RWMSs). The Area 3 and Area 5 RWMSs were issued Disposal Authorization Statements (DASs) in accordance with U.S. Department of Energy Order DOE O 435.1 “Radioactive Waste Management” (U.S. Department of Energy [DOE] 2001). The Area 3 RWMS and Area 5 RWMS DASs (DOE 1999a, 2000) require preparation of an annual summary report and a determination of the continuing adequacy of the PAs and CAs. The requirement to prepare an annual summary report is implemented in the Maintenance Plan for the PAs and CAs (National Security Technologies, LLC [NSTec] 2007a). The annual summary report is submitted to the DOE Office of Environmental Management for review and approval.

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Ecological risk assessment software for radioactive waste management facilities - 15464

Environmental Risk Assessment (ERA) is a systematic process which can be used to identify, quantify and characterize the risk posed by contaminants and physical stressors in the environment on biological receptors, including human and non-human biota. Human receptors can be addressed through a Human Health Risk Assessment and non-human biota can be addressed through an Ecological Risk Assessment (EcoRA). In 2012 the Canadian Standards Association (CSA) issued a CSA standard N288.6 Environmental Risk Assessment at Class I Nuclear Facilities and Uranium Mines and Mills. The standard applies to radioactive waste management facilities, as well as nuclear power plants. The ERA can also be used retrospectively, to estimate the effect that a contaminant or stressor has already had on the environment; and can be used to assist in determining possible remedial or risk management options to return the quality of the affected environment to a predetermined state. While industry-standard tools for estimating radiological doses to humans are readily available, there is a need for a tool to implement the CSA N288.6 standard for Ecological Risk Assessment. To address this need, AMEC developed a computer code called -Assessment of Impact of Contaminants on Ecological Receptors (AICER)-. The code was developed to be consistent with the CSA standard N288.6, by assessing the impact of radiological contamination on non-human biota for normal operations. The code can also be used to screen for the potential effects of conventional contamination on the environment. In addition, the code is also applicable for abnormal events and accidents with the appropriate modification of some parameters used in the code. The AICER code was qualified in accordance with the requirements of the Canadian quality standard CSA N286.7 -Quality Assurance of Analytical, Scientific, and Design Computer Programs for Nuclear Power Plants-. The functionality of the code is illustrated with screen shots in the paper, following the introduction of the theoretical model for the dose calculation. An inter-comparison with RESRAD-BIOTA and ERICA Assessment tool at the conceptual level was conducted. In addition, the practical application of the code for the assessment of the impacts related to an existing radioactive waste management facility is provided. In particular, analysis was conducted to evaluate radiological doses to non-human biota resulting from a fire accident scenario involving an existing waste storage and processing facility. Analysis included all feasible waterborne and airborne exposure pathways. Doses were evaluated for a range of species representing valued ecological components at various trophic levels and compared with benchmark values for indicator species. (authors)

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Nevada National Security Site 2014 Data Report: Groundwater Monitoring Program Area 5 Radioactive Waste Management Site

This report is a compilation of the groundwater sampling results from the Area 5 Radioactive Waste Management Site (RWMS) at the Nevada National Security Site, Nye County, Nevada. Groundwater samples from the aquifer immediately below the Area 5 RWMS have been collected and analyzed and static water levels have been measured in this aquifer since 1993. This report updates these data to include the 2014 results. Analysis results for leachate contaminants collected from the mixed-waste cell at the Area 5 RWMS (Cell 18) are also included. During 2014, groundwater samples were collected and static water levels were measured at three wells surrounding the Area 5 RWMS. Groundwater samples were collected at wells UE5PW-1, UE5PW-2, and UE5PW-3 on March 11 and August 12, 2014, and static water levels were measured at each of these wells on March 10, June 2, August 11, and October 14, 2014. Groundwater samples were analyzed for the following indicators of contamination: pH, specific conductance, total organic carbon, total organic halides, and tritium. General water chemistry (cations and anions) was also measured. Results from samples collected in 2014 are within the limits established by agreement with the Nevada Division of Environmental Protection for each analyte. The data from the shallow aquifer indicate that there has been no measurable impact to the uppermost aquifer from the Area 5 RWMS, and there were no significant changes in measured groundwater parameters compared to previous years. Leachate from above the primary liner of Cell 18 drains into a sump and is collected in a tank at the ground surface. Cell 18 began receiving waste in January 2011. Samples were collected from the tank when the leachate volume approached the 3,000-gallon tank capacity. Leachate samples have been collected 16 times since January 2011. During 2014, samples were collected on February 25, March 5, May 20, August 12, September 16, November 11, and December 16. Each leachate sample was analyzed for toxicity characteristic contaminants and polychlorinated biphenyls (PCB). Beginning with the sample from July 31, 2013, pH and specific conductance were also measured. Leachate analysis results show no evidence of contamination. Results for toxicity characteristic contaminants are all below regulatory levels and analysis quantification limits. No quantifiable PCB levels were detected in any sample. Results for pH and specific conductance are also within expected ranges. After analysis, leachate was pumped from the collection tank and used in Cell 18 for dust control. The report contains an updated cumulative chronology for the Area 5 RWMS Groundwater Monitoring Program and a brief description of the site hydrogeology.

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Final Closure of the Maxey Flats Low-Level Radioactive Waste Disposal Site - 16088

This paper describes the final closure remedy for the former Maxey Flats Low-Level Radioactive Waste Disposal Site (MFDS), the challenges presented at the site due to the condition of the disposal facility and waste, and their resolution through comprehensive geo-synthetic design. The MFDS is an inactive landfill located in Kentucky on a ridge surrounded by a buffer zone. Historically, waste disposal occurred without reducing voids or without compacting the placed waste. Settlement and water management issues led to releases of radioactive contamination into surrounding waters, resulting in the closure of the facility in 1977. The final closure remedy consists of 1) development and implementation oversight of a sump abandonment design to ensure no direct pathways for infiltrating water to contact the waste and 2) development and implementation oversight of the Final Closure Period (FCP) cap design. Challenges successfully addressed by the FCP scope included: Abandon sumps to minimize storm water migrating into the waste; Address potential existing groundwater waste interaction; Maximum use of on-site cap construction materials; Design cap to fit very restricted site footprint; Assess and address potential isolated differential settlement; Maximize passive storm water management; Provide alternative site access during construction. The FCP remedy and resultant design satisfies these challenges through use of layers of geo-grid-reinforced soil and geo-synthetic materials, contours and slopes that minimize the quantities of construction materials while maximizing the use of available material, probabilistic subsidence modeling, an integrated storm water management system ensuring the slow release of storm water into receiving streams, and a dedicated construction haul road system. (authors)

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Milestones for Selection, Characterization, and Analysis of the Performance of a Repository for Spent Nuclear Fuel and High-Level Radioactive Waste at Yucca Mountain.

This report presents a concise history in tabular form of events leading up to site identification in 1978, site selection in 1987, subsequent characterization, and ongoing analysis through 2009 of the performance of a repository for spent nuclear fuel and high - level radioactive waste at Yucca Mountain in southern Nevada. The tabulated events generally occurred in five periods: (1) commitment to mined geologic disposal and identification of sites; (2) site selection and analysis, based on regional geologic characterization through literature and analogous data; (3) feasibility analysis demonstrating calculation procedures and importance of system components, based on rough measures of performance using surface exploration, waste process knowledge, and general laboratory experiments; (4) suitability analysis demonstrating viability of disposal system, based on environment - specific laboratory experiments, in - situ experiments, and underground disposal system characterization; and (5) compliance analysis, based on completed site - specific characterization . The current sixth period beyond 2010 represents a new effort to set waste management policy in the United States. Because the relationship is important to understanding the evolution of the Yucca Mountain Project , the tabulation also shows the interaction between the policy realm and technical realm using four broad categories of events : (a) Regulatory requirements and related federal policy in laws and court decisions, (c) Presidential and agency directives, (c) technical milestones of implementing institutions, and (d) critiques of the Yucca Mountain Project and pertinent national and world events related to nuclear energy and radioactive waste. Preface The historical progression of technical milestones for the Yucca Mountain Project was originally developed for 10 journal articles in a special issue of Reliability Engineering System Safety on the performance assessment for the Yucca Mountain license application [1-10]. The listing of mile stones, a distinct feature of those articles, has been collected and tabulated here. A lthough a brief description is presented here (based on the summaries in the 10 journal articles), the emphasis remains on the tabulation because of its usefulness in providing a comprehensive but concise history of the Yucca Mountain Project. The tabulation presented here is more elaborate than originally presented in that many of the interactions that occurred between the technical realm and policy realm can be depicted in separate columns. The usefulness of the milestones table is due in part to L.A. Connolly, for editorial and reference support, and S.K. Best, Raytheon, and L. Mays, Sandia National Laboratories (SNL), for illustration support. Reviewers P.N. Swift, SNL, and K. Gupta, University of Oklahoma, helped improve the discussion. The historical perspective presented is that of the author and is not necessarily held by reviewers, Sandia National Laboratories , and the US Department of Energy. As a historic perspective, the author is reporting on the work of others; however, any interpretative error s of the documentation are those of the author alone. The characterization and modeling of the Yucca Mountain disposal system required numerous participants with expertise in many areas of science and technology, as evident from the extensive reference list. Their diligent efforts are generally acknowledged here and through the many references to their impressive work, but the 10 journal articles acknowledge by name many of the numerous participants that contributed to the Yucca Mountain Project .

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