10 research outputs found
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Comparison of alternative treatment systems for DOE mixed low-level waste
From 1993 to 1996, the Department of Energy, Environmental Management, Office of Science and Technology (OST), has sponsored a series of systems analyses to guide its future research and development (R&D) programs for the treatment of mixed low-level waste (MLLW) stored in the DOE complex. The two original studies were of 20 mature and innovative thermal systems. As a result of a technical review of these thermal system studies, a similar study of five innovative nonthermal systems was conducted in which unit operations are limited to temperatures less than 350{degrees}C to minimize volatilization of heavy metals and radionuclides, and de novo production of dioxins and furans in the offgas. Public involvement in the INTS study was established through a working group of 20 tribal and stakeholder representatives to provide input to the INTS studies and identify principles against which the systems should be designed and evaluated. Pre-conceptual designs were developed for all systems to treat the same waste input (2927 lbs/hr) in a single centralized facility operating 4032 hours per year for 20 years. This inventory consisted of a wide range of combustible and non-combustible materials such as paper, plastics, metals, concrete, soils, sludges, liquids, etc., contaminated with trace quantities of radioactive materials and RCRA regulated wastes. From this inventory, an average waste profile was developed for simulated treatment using ASPEN PLUS{copyright} for mass balance calculations. Seven representative thermal systems were selected for comparison with the five nonthermal systems. This report presents the comparisons against the TSWG principles, of total life cycle cost (TLCC), and of other system performance indicators such as energy requirements, reagent requirements, land use, final waste volume, aqueous and gaseous effluents, etc
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Comparison of costs for alternative mixed low-level waste treatment systems
Total life cycle costs (TLCCs), including disposal costs, of thermal, nonthermal and enhanced nonthermal systems were evaluated to guide future research and development programs for the treatment of mixed low-level waste (MLLW) consisting of RCRA hazardous and low-level radioactive wastes. In these studies, nonthermal systems are defined as those systems that process waste at temperatures less than 350 C. Preconceptual designs and costs were developed for thirty systems with a capacity (2,927 lbs/hr) to treat the DOE MLLW stored inventor y(approximately 236 million pounds) in 20 years in a single, centralized facility. A limited comparison of the studies` results is presented in this paper. Sensitivity of treatment costs with respect to treatment capacity, number of treatment facilities, and system availability were also determined. The major cost element is operations and maintenance (O and M), which is 50 to 60% of the TLCC for both thermal and nonthermal systems. Energy costs constitute a small fraction (< 1%) of the TLCCs. Equipment cost is only 3 to 5% of the treatment cost. Evaluation of subsystem costs demonstrate that receiving and preparation is the highest cost subsystem at about 25 to 30% of the TLCC for both thermal and nonthermal systems. These studies found no cost incentives to use nonthermal or hybrid (combined nonthermal treatment with stabilization by vitrification) systems in place of thermal systems. However, there may be other incentives including fewer air emissions and less local objection to a treatment facility. Building multiple treatment facilities to treat the same total mass of waste as a single facility would increase the total treatment cost significantly, and improved system availability decreases unit treatment costs by 17% to 30%
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Portable treatment systems study
In developing their Site Treatment Plans (STPs), many of the Department of Energy installations identified some form of portable treatment, to facilitate compliant disposition of select mixed low-level wastestreams. The Environmental Management Office of Science and Technology requested that a systems study be performed to better define the potential role of portable treatment with respect to mixed low-level waste, highlight obstacles to implementation, and identify opportunities for future research and development emphasis. The study was performed by first establishing a representative set of mixed waste, then formulating portable treatment system concepts to meet the required processing needs for these wastes. The portable systems that were conceptualized were evaluated and compared to a fixed centralized treatment alternative. The system evaluations include a life-cycle cost analysis and an assessment of regulatory, institutional, and technical issues associated with the potential use of portable systems. The results of this study show that when all costs are included, there are no significant cost differences between portable systems and fixed systems. However, it is also emphasized that many uncertainties exist that could impact the cost of implementing portable treatment systems. Portable treatment could be made more attractive through private sector implementation, although there is little economic incentive for a commercial vendor to develop small, specialized treatment capabilities with limited applicability. Alternatively, there may also be valid reasons why fixed units cannot be used for some problematic wastestreams. In any event, there are some site-specific problems that still need to be addressed, and there may be some opportunity for research and development to make a positive impact in these areas
Analysis of concentrating PV-T systems for the commercial/industrial sector. Volume II. PV-T state-of-the-art survey and site/application pair selection and analysis
As part of a project to develop feasibility assessments, design procedures, and reference designs for total energy systems that could use actively cooled concentrating photovoltaic collectors, a survey was conducted to provide an overview of available photovoltaic-thermal (PV-T) technology. General issues associated with the design and installation of a PV-T system are identified. Electrical and thermal efficiencies for the line-focus Fresnel, the linear parabolic trough, and the point-focus Fresnel collectors are specified as a function of operating temperature, ambient temperature, and insolation. For current PV-T technologies, the line-focus Fresnel collector proved to have the highest thermal and electrical efficiencies, lowest array cost, and lowest land area requirement. But a separate feasibility analysis involving 11 site/application pairs showed that for most applications, the cost of the photovoltaic portion of a PV-T system is not recovered through the displacement of an electrical load, and use of a thermal-only system to displace the thermal load would be a more economical alternative. PV-T systems are not feasible for applications that have a small thermal load, a large steam requirement, or a high load return temperature. SAND82-7157/3 identifies the technical issues involved in designing a photovoltaic-thermal system and provides guidance for resolving such issues. Detailed PV-T system designs for three selected applications and the results of a trade-off study for these applications are presented in SAND82-7157/4. A summary of the major results of this entire study and conclusions concerning PV-T systems and applications is presented in SAND82-7157/1
Analysis of concentrating PV-T systems for the commercial/industrial sector. Volume IV. Design analysis and trade-off study
Detailed reference designs developed for optimally sized photovoltaic-thermal (PV-T) systems are presented for three selected applications. The results of trade-off analyses to determine the effects of load variations, new components, changes in location, and variations in array cost are also discussed
Analysis of concentrating PV-T systems for the commercial/industrial sector. Volume III. Technical issues and design guidance
This report provide appropriate guidance for addressing the major technical issues associated with the design and installation of a photovoltaic-thermal (PV-T) system. Nomographs are presented for developing preliminary sizing and costing, and issues associated with specific components and the overall design of the electrical and mechanical system are discussed. SAND82-7157/2 presents a review of current PV-T technology and operating systems and a study of potential PV-T applications. Detailed PV-T system designs for three selected applications and the results of a trade-off study for these applications are presented in SAND82-7157/4. A summary of the major results of this entire study and conclusions concerning PV-T systems and applications is presented in SAND82-7157/1
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Costs of mixed low-level waste stabilization options
Selection of final waste forms to be used for disposal of DOE`s mixed low-level waste (MLLW) depends on the waste form characteristics and total life cycle cost. In this paper the various cost factors associated with production and disposal of the final waste form are discussed and combined to develop life-cycle costs associated with several waste stabilization options. Cost factors used in this paper are based on a series of treatment system studies in which cost and mass balance analyses were performed for several mixed low-level waste treatment systems and various waste stabilization methods including vitrification, grout, phosphate bonded ceramic and polymer. Major cost elements include waste form production, final waste form volume, unit disposal cost, and system availability. Production of grout costs less than the production of a vitrified waste form if each treatment process has equal operating time (availability) each year; however, because of the lower volume of a high temperature slag, certification and handling costs and disposal costs of the final waste form are less. Both the total treatment cost and life cycle costs are higher for a system producing grout than for a system producing high temperature slag, assuming equal system availability. The treatment costs decrease with increasing availability regardless of the waste form produced. If the availability of a system producing grout is sufficiently greater than a system producing slag, then the cost of treatment for the grout system will be less than the cost for the slag system, and the life cycle cost (including disposal) may be less depending on the unit disposal cost. Treatment and disposal costs will determine the return on investment in improved system availability
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Integrated process analysis of treatment systems for mixed low level waste
Selection of technologies to be developed for treatment of DOE`s mixed low level waste (MLLW) requires knowledge and understanding of the expected costs, schedules, risks, performance, and reliability of the total engineered systems that use these technologies. Thus, an integrated process analysis program was undertaken to identify the characteristics and needs of several thermal and nonthermal systems. For purposes of comparison, all systems were conceptually designed for a single facility processing the same amount of waste at the same rate. Thirty treatment systems were evaluated ranging from standard incineration to innovative thermal systems and innovative nonthermal chemical treatment. Treating 236 million pounds of waste in 20 years through a central treatment was found to be the least costly option with total life cycle cost ranging from 3.9 billion for a nonthermal acid digestion system. Little cost difference exists among nonthermal systems or among thermal systems. Significant cost savings could be achieved by working towards maximum on line treatment time per year; vitrifying the final waste residue; decreasing front end characterization segregation and sizing requirements; using contaminated soil as the vitrifying agent; and delisting the final vitrified waste form from Resource Conservation and Recovery Act (RCRA) Land Disposal Restriction (LDR) requirements
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Evaluation of alternative nonflame technologies for destruction of hazardous organic waste
The US Department of Energy`s Mixed Waste Focus Area (MWFA) commissioned an evaluation of mixed waste treatment technologies that are alternatives to incineration for destruction of hazardous organic wastes. The purpose of this effort is to evaluate technologies that are alternatives to open-flame, free-oxygen combustion (as exemplified by incinerators), and recommend to the Waste Type Managers and the MWFA which technologies should be considered for further development. Alternative technologies were defined as those that have the potential to: destroy organic material without use of open-flame reactions with free gas-phase oxygen as the reaction mechanism; reduce the offgas volume and associated contaminants (metals, radionuclides, and particulates) emitted under normal operating conditions; eliminate or reduce the production of dioxins and furans; and reduce the potential for excursions in the process that can lead to accidental release of harmful levels of chemical or radioactive materials. Twenty-three technologies were identified that have the potential for meeting these requirements. These technologies were rated against the categories of performance, readiness for deployment, and environment safety, and health. The top ten technologies that resulted from this evaluation are Steam Reforming, Electron Beam, UV Photo-Oxidation, Ultrasonics, Eco Logic reduction process, Supercritical Water oxidation, Cerium Mediated Electrochemical Oxidation, DETOX{sup SM}, Direct Chemical Oxidation (peroxydisulfate), and Neutralization/Hydrolysis
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Alternatives to incineration. Technical area status report
Recently, the DOE`s Mixed Waste Integrated Program (MWIP) (superseded by the Mixed Waste Focus Area) initiated an evaluation of alternatives to incineration to identify technologies capable of treating DOE organically contaminated mixed wastes and which may be more easily permitted. These technologies have the potential of alleviating stakeholder concerns by decreasing off-gas volurties and the associated emissions of particulates, volatilized metals and radionuclides, PICs, NO{sub x}, SO{sub x}, and recombination products (dioxins and furans). Ideally, the alternate technology would be easily permitted, relatively omnivorous and effective in treating a variety of wastes with varying constituents, require minimal pretreatment or characterization, and be easy to implement. In addition, it would produce secondary waste stream volumes significantly smaller than the original waste stream, and would minimize the environmental health and safety effects on workers and the public. The purpose of this report is to provide an up-to-date (as of early 1995) compendium of iternative technologies for designers of mixed waste treatment facilities, and to identify Iternate technologies that may merit funding for further development. Various categories of non-thermal and thermal technologies have been evaluated and are summarized in Table ES-1. Brief descriptions of these technologies are provided in Section 1.7 of the Introduction. This report provides a detailed description of approximately 30 alternative technologies in these categories. Included in the report are descriptions of each technology; applicable input waste streams and the characteristics of the secondary, or output, waste streams; the current status of each technology relative to its availability for implementation; performance data; and costs. This information was gleaned from the open literature, governments reports, and discussions with principal investigators and developers