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Development Of An Accelerated Leach Tests For Low Level Waste Forms
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Book Synopsis Development of an Accelerated Leach Test(s) for Low-level Waste Forms by :
Download or read book Development of an Accelerated Leach Test(s) for Low-level Waste Forms written by and published by . This book was released on 1985 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: An accelerated leach test(s) is being developed to predict long-term leaching behavior of low-level radioactive waste (LLW) forms in their disposal environments. As necessary background, a literature survey of reported leaching mechanisms, available mathematical models and factors that affect leaching of LLW forms has been compiled. Mechanisms which have been identified include diffusion, dissolution, ion exchange, corrosion and surface effects. A computerized data base of LLW leaching data and mathematical models is being developed. The data is being used for model evaluation by curve fitting and statistical analysis according to standard procedures of statistical quality control. Long-term leach tests on portland cement, bitumen and vinyl ester-styrene (VES) polymer waste forms are underway which are designed to identify and evaluate factors that accelerate leaching without changing the mechanisms. Initial results on the effect of temperature on leachability indicate that the leach rates of cement and VES waste forms increase with increasing temperature, whereas, the leach rate of bitumen is little affected. 10 refs., 5 figs.
Book Synopsis Progress in Development of an Accelerated Leach Test for Low-level Radioactive Waste Forms by :
Download or read book Progress in Development of an Accelerated Leach Test for Low-level Radioactive Waste Forms written by and published by . This book was released on 1987 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Factors that accelerate leaching from solidified low-level radioactive waste are being investigated to develop a short-term leach test that can be used to predict long-term releases. Data from work with portland cement containing radioactive tracers indicate that elevated temperatures can accelerate leaching of Ce-137 by at least a factor of eleven without changing the leaching mechanism. An 18 day leach test at 50°C provided the equivalent of 200 days data taken at 20°C. Portland cement containing 5 wt % Na2SO4 also can be accelerated, but to a lesser degree. Solid phase analysis indicated that pore plugging and increased tortuosity may be the cause of the smaller acceleration. Reduced specimen size was also a useful acceleration factor with inhomogeneities not being a problem in very small specimens. Elevated pH and 100 ppM EDTA in leaching solutions increased Sr-85 releases without altering Cs-137 leaching. 9 refs., 10 figs., 1 tab.
Book Synopsis Progress in Development of an Accelerated Leach Test for Low-level Radioactive Waste Forms by :
Download or read book Progress in Development of an Accelerated Leach Test for Low-level Radioactive Waste Forms written by and published by . This book was released on 1987 with total page 13 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Development of a Computerized Data Base for Low-level Radioactive Waste Leaching Data by :
Download or read book Development of a Computerized Data Base for Low-level Radioactive Waste Leaching Data written by and published by . This book was released on 1986 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This report documents the development of a computerized data base (db) of leaching data for solidified low-level radioactive waste (LLW) forms. Brookhaven National Lab performed this work under contract with the US Department of Energy's Low-Level Waste Management Program as part of an effort to develop an accelerated leach test(s) that can be used to predict leachabilities of LLW forms over long time periods, i.e., hundreds of years. The accelerated leach test(s) is (are) to be developed based on knowledge of leaching mechanisms and factors that affect leaching. Although developed specifically for the Accelerated Leach Test(s) Program, this db may be useful to others concerned with the management of low-level waste. The db is being developed to provide efficient data compilation and analysis capabilities. The data compiled in the db, which include data from the Accelerated Leach Test(s) Program and selected data from the literature, have been selected to elucidate leaching mechanisms and factors that affect leaching and are not meant to be a comprehensive compilation of leaching data. This report presents the data compilation aspect of the db. It does not present the programmatic results obtained from analysis of the data regarding leaching mechanisms and factors that affect leaching, which will be presented in reports from the Accelerated Leach Test(s) Program. 6 refs.
Book Synopsis Development of an Accelerated Leach Test(s) for Low-level Waste Forms by :
Download or read book Development of an Accelerated Leach Test(s) for Low-level Waste Forms written by and published by . This book was released on 1985 with total page 14 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Optimizing Conditions for an Accelerated Leach Test by :
Download or read book Optimizing Conditions for an Accelerated Leach Test written by and published by . This book was released on 1988 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: An accelerated leach test for low-level radioactive waste forms is being developed to provide, in a short time, data that can be extrapolated to long time periods. The approach is to provide experimental conditions that will accelerate leaching without changing the dominant release mechanism. Experimental efforts have focused on combining individual factors that have been observed to accelerate leaching. These include elevated temperature, increased leachant volume, and reduced specimen size. The response of diffusion coefficients to various acceleration factors have been evaluated and provide information on experimental parameters that need to be optimized to increase leach rates. For example, these data show that large volumes of leachant are required when leaching portland cement waste forms at elevated temperatures because of high concentrations of dissolved species. Sr-85 leaching is particularly susceptible to suppression due to concentration effects while Cs-137 leaching is less so. Preliminary modeling using a diffusion mechanism (allowing for depletion) of a finite cylinder geometry indicates that during early portions of experiments (daily sampling intervals), leaching is diffusion controlled and more rapid than later in the same experiments (weekly or greater sampling intervals). For cement waste forms, this reduction in rate may be partially controlled by changes in physical structure and chemistry (sometimes related to environmental influences such as CO2), but it is more likely associated with the duration of the sampling interval. 9 refs., 6 figs.
Book Synopsis Development of a Computerized Data Base for Low-level Waste Leaching Data by :
Download or read book Development of a Computerized Data Base for Low-level Waste Leaching Data written by and published by . This book was released on 1986 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: A computerized data base of low-level waste (LLW) leaching data is being compiled by Brookhaven National Laboratory. Although this data base is being compiled as part of an effort to develop accelerated leach test procedures for LLW forms, others involved in LLW management may find it useful. The data base is implemented on an IBM PC XT and is self-contained in that its data manipulation and analysis programs are not proprietary (i.e., need not be purchased). The data base includes data from the Accelerated Leach Test(s) Program plus selected literature data, which have been selected based on criteria that include completeness of the experimental description and elucidation of leaching mechanisms.
Book Synopsis Optimization of the Factors that Accelerate Leaching by :
Download or read book Optimization of the Factors that Accelerate Leaching written by and published by . This book was released on 1989 with total page 138 pages. Available in PDF, EPUB and Kindle. Book excerpt: The prediction of long-term leachability of low-level radioactive waste forms is an essential element of disposal-site performance assessment. This report describes experiments and modeling techniques used to develop an accelerated leach test that meets this need. The acceleration in leaching rates caused by the combinations of two or more factors were experimentally determined. These factors were identified earlier as being able to individually accelerate leaching. They are: elevated temperature, the size of the waste form, the ratio of the volume of leachant to the surface area of the waste form, and the frequency of replacement of the leachant. The solidification agents employed were ones that are currently used to treat low-level radioactive wastes, namely portland type I cement, bitumen, and vinyl ester-styrene. The simulated wastes, sodium sulfate, sodium tetraborate, and incinerator ash, are simplified representatives of typical low-level waste streams. Experiments determined the leaching behavior of the radionuclides of cesium (Cs-137), strontium (Sr-85), and cobalt (Co-60 or Co-57) from several different formulations of solidification agents and waste types. Leaching results were based upon radiochemical and elemental analyses of aliquots of the leachate, and on its total alkalinity and pH at various times during the experiment (up to 120 days). Solid phase analyses were carried out by Scanning/Electron Microscopy and Energy Dispersive Spectroscopy on the waste forms before and after some leaching experiments. 43 refs., 96 figs., 16 tabs.
Book Synopsis Accelerated Leach Test Development Program by :
Download or read book Accelerated Leach Test Development Program written by and published by . This book was released on 1990 with total page 65 pages. Available in PDF, EPUB and Kindle. Book excerpt: In FY 1989, a draft accelerated leach test for solidified waste was written. Combined test conditions that accelerate leaching were validated through experimental and modeling efforts. A computer program was developed that calculates test results and models leaching mechanisms. This program allows the user to determine if diffusion controls leaching and, if this is the case, to make projections of releases. Leaching mechanisms other than diffusion (diffusion plus source term partitioning and solubility limited leaching) are included in the program is indicators of other processes that may control leaching. Leach test data are presented and modeling results are discussed for laboratory scale waste forms composed of portland cement containing sodium sulfate salt, portland cement containing incinerator ash, and vinyl ester-styrene containing sodium sulfate. 16 refs., 38 figs., 5 tabs.
Book Synopsis Accelerated Leach Test(s) Program. Annual Report by :
Download or read book Accelerated Leach Test(s) Program. Annual Report written by and published by . This book was released on 1985 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This report summarizes the work performed for the Accelerated Leach Test(s) Program at Brookhaven National Laboratory in Fiscal Year 1985 under the sponsorship of the US Department of Energy's Low-Level Waste Management Program (LLWMP). Programmatic activities were concentrated in three areas, as listed and described in the following paragraphs. (1) A literature survey of reported leaching mechanisms, available mathematical models and factors that affect leaching of LLW forms has been compiled. Mechanisms which have been identified include diffusion, dissolution, ion exchange, corrosion and surface effects. Available mathematical models are based on diffusion as the predominant mechanism. Although numerous factors that affect leaching have been identified, they have been conveniently categorized as factors related to the entire leaching system, to the leachant or to the waste form. A report has been published on the results of this literature survey. (2) A computerized data base of LLW leaching data and mathematical models is being developed. The data are being used for model evaluation by curve fitting and statistical analysis according to standard procedures of statistical quality control. (3) Long-term tests on portland cement, bitumen and vinyl ester-styrene (VES) polymer waste forms are underway which are designed to identify and evaluate factors that accelerate leaching without changing the mechanisms. Results on the effect of temperature on leachability indicate that the leach rates of cement and VES waste forms increase with increasing temperature, whereas, the leach rate of bitumen is little affected.
Book Synopsis Users' Guide for the Accelerated Leach Test Computer Program by :
Download or read book Users' Guide for the Accelerated Leach Test Computer Program written by and published by . This book was released on 1990 with total page 165 pages. Available in PDF, EPUB and Kindle. Book excerpt: This report is a step-by-step guide for the Accelerated Leach Test (ALT) Computer Program developed to accompany a new leach test for solidified waste forms. The program is designed to be used as a tool for performing the calculations necessary to analyze leach test data, a modeling program to determine if diffusion is the operating leaching mechanism (and, if not, to indicate other possible mechanisms), and a means to make extrapolations using the diffusion models. The ALT program contains four mathematical models that can be used to represent the data. The leaching mechanisms described by these models are: (1) diffusion through a semi-infinite medium (for low fractional releases), (2) diffusion through a finite cylinder (for high fractional releases), (3) diffusion plus partitioning of the source term, (4) solubility limited leaching. Results are presented as a graph containing the experimental data and the best-fit model curve. Results can also be output as LOTUS 1-2-3 files. 2 refs.
Download or read book Radioactive Waste Management written by and published by . This book was released on 1981 with total page 630 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Strategy and Methodology for Radioactive Waste Characterization by : International Atomic Energy Agency
Download or read book Strategy and Methodology for Radioactive Waste Characterization written by International Atomic Energy Agency and published by IAEA. This book was released on 2007 with total page 188 pages. Available in PDF, EPUB and Kindle. Book excerpt: Over the past decade significant progress has been achieved in the development of waste characterization and control procedures and equipment as a direct response to ever-increasing requirements for quality and reliability of information on waste characteristics. Failure in control procedures at any step can have important, adverse consequences and may result in producing waste packages which are not compliant with the waste acceptance criteria for disposal, thereby adversely impacting the repository. The information and guidance included in this publication corresponds to recent achievements and reflects the optimum approaches, thereby reducing the potential for error and enhancing the quality of the end product. -- Publisher's description.
Download or read book Energy Research Abstracts written by and published by . This book was released on 1993-08 with total page 472 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Waste Forms Technology and Performance by : National Research Council
Download or read book Waste Forms Technology and Performance written by National Research Council and published by National Academies Press. This book was released on 2011-09-05 with total page 308 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Department of Energy's Office of Environmental Management (DOE-EM) is responsible for cleaning up radioactive waste and environmental contamination resulting from five decades of nuclear weapons production and testing. A major focus of this program involves the retrieval, processing, and immobilization of waste into stable, solid waste forms for disposal. Waste Forms Technology and Performance, a report requested by DOE-EM, examines requirements for waste form technology and performance in the cleanup program. The report provides information to DOE-EM to support improvements in methods for processing waste and selecting and fabricating waste forms. Waste Forms Technology and Performance places particular emphasis on processing technologies for high-level radioactive waste, DOE's most expensive and arguably most difficult cleanup challenge. The report's key messages are presented in ten findings and one recommendation.
Book Synopsis The Effects of Temperature on the Leaching Behavior of Cement Waste Forms by :
Download or read book The Effects of Temperature on the Leaching Behavior of Cement Waste Forms written by and published by . This book was released on 1989 with total page 7 pages. Available in PDF, EPUB and Kindle. Book excerpt: The leaching mechanisms of simulated low-level radioactive waste forms are being determined as support for development of an accelerated leach test. Two approaches are being used: (1) comparisons of leaching data with results of a model that describes diffusion from a finite cylinder, and (2) observation of the leaching process at temperatures between 20°C and 65°C. To provide results that can be used for modeling, leaching at elevated temperatures must change neither the leaching mechanism nor the structural controls of leaching such as the porosity. Releases of 137Cs, 85Sr, calcium, sodium and potassium from portland cement containing sodium sulfate, as a simulated evaporator sludge, have been determined under a variety of experimental conditions. Data from the leach tests were compared to model results for diffusion from the finite cylinder. While most leaching appears to be diffusion controlled, notable exceptions occur. For all samples activation energies ranging between 6 and 11 Kcal/mole have been calculated from the relationship of the effective diffusion coefficient to increasing temperature, close to the expected value of 5 Kcal/mole for diffusion. 11 refs., 4 figs., 2 tabs.
Book Synopsis Selected Water Resources Abstracts by :
Download or read book Selected Water Resources Abstracts written by and published by . This book was released on 1988 with total page 1198 pages. Available in PDF, EPUB and Kindle. Book excerpt:
