2,522 research outputs found

    Mixed Low-Level Radioactive and Hazardous Waste Disposal Facilities

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    Candidate sites for disposal of USDOE’s Mixed Wastes (MW), must be judged according to their hydrogeology over an appropriate time frame: up to 10,000 years. US Department of Energy (USDOE) has identified three options for disposal of vast quantities of Mixed Waste. Those three options include the Hanford Nuclear Reservation (alongside the Columbia River in Washington), Nevada Test Site (NTS) and at a private facility in Clive, Utah run by Envirocare of Utah (whose parent company was recently renamed “EnviroSolutions”). The quantities of wastes that might be added to the soils at these sites are enormous.1 All three are currently disposing of Mixed Waste or in the process of permitting for this purpose. In this report, for the first time, the alternative sites for disposal of Mixed Waste are independently compared in regard to their fundamental geologic and hyrodologic conditions, design, standards utilized, and actual monitoring. A fundamental conclusion of the report by John Brodeur, L.G.E, P.E., is that the hydrogeologic landscape determines the fundamental scale of impacts to the environment and human health – regardless of MLL Radioactive & Hazardous Waste Facilities 6 engineering efforts. In sum, the site matters. In addition to the site, the design and actual operation are shown to matter a great deal, and we find tremendous differences exist between alternative sites. This publication is a compilation of research and work products undertaken during the duration of a CitizensMonitoring and Technical Assistance Fund grant from 2004 through March 2006, to create a Cross-Site Review of Mixed Waste Disposal Facilities, and review Hanford specific landfill related documents and decisions. While comparing the three major alternative disposal sites (Hanford, NTS and Envirocare), four specific burial grounds were considered at the Hanford Nuclear Reservation: Environmental Restoration Disposal Facility (ERDF); Integrated Disposal Facility (IDF); US Ecology Commercial Low-Level Waste landfill; and, USDOE’s Hanford Low-Level Burial Grounds (LLGB). This research was completed money allocated during Round 5 of the Citizens’ Monitoring and Technical Assessment Fund (MTA Fund). Clark University was named conservator of these works. If you have any questions or concerns please contact us at [email protected]://commons.clarku.edu/heartofam/1005/thumbnail.jp

    A Review and Comparison of Low-Level Radioactive Waste Disposal Facilities

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    In 2002, the Department of Energy (DOE) released the draft Hanford Solid Waste Environmental Impact Statement (DOE 2002). That draft called for the disposal of over 12 million cubic feet of low-level radioactive waste (LLRW) at Hanford in unlined near-surface disposal trenches. The draft EIS was withdrawn by USDOE following public comment, as urged by numerous official agency, advisory board and public commentators. In April, 2003, USDOE issued the Revised Draft Hanford Solid Waste EIS, which forecast that USDOE would dispose of up to 12.3 million cubic feet of LLRW in near-surface burial trenches.1 Sixty three percent (63%) of this LLRW would be imported to Hanford for burial. At an undefined future date, the Revised Draft EIS proposed that LLRW would be buried together in new trenches with up to 5 million cubic feet of Mixed Low-Level Waste, which is Low-Level Radioactive Waste mixed with hazardous chemical wastes.2 To develop a technical position on the proposal for use of Hanford newr- surface burial for Low-Level Wastes, Heart of America NW wanted to know if the Low-Level Radioactive Waste Burial Grounds meet the basic engineering requirements for such facilities and how they compare with other similar facilities and alternative potential disposal sites available to USDOE for these wastes. As such, this report represents the first independent, publicly available Cross-Site Comparison of USDOE Low-Level Radioactive Waste Burial Ground Alternatives. Performing a complete engineering review of multiple facilities was clearly beyond the potential budget capacity so a proposal was proffered to limit the investigation to the geotechnical aspects of representative LLRW disposal facilities. This type of focused review was accomplished by visiting the sites and reviewing documentation on the sites. Performance standards and review criteria were identified and the disposal facilities were evaluated to determine how well they meet the performance standards. This is the basis for a comparison of the facilities. This report presents the results of this study. This research was completed money allocated during Round 3 of the Citizens’ Monitoring and Technical Assessment Fund (MTA Fund). Clark University was named conservator of these works. If you have any questions or concerns please contact us at [email protected]://commons.clarku.edu/heartofam/1000/thumbnail.jp

    Expressing Measurement Uncertainty in OCL/UML Datatypes

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    Uncertainty is an inherent property of any measure or estimation performed in any physical setting, and therefore it needs to be considered when modeling systems that manage real data. Although several modeling languages permit the representation of measurement uncertainty for describing certain system attributes, these aspects are not normally incorporated into their type systems. Thus, operating with uncertain values and propagating uncertainty are normally cumbersome processes, di cult to achieve at the model level. This paper proposes an extension of OCL and UML datatypes to incorporate data uncertainty coming from physical measurements or user estimations into the models, along with the set of operations de ned for the values of these types.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

    Direct and indirect costs of nephrolithiasis in an employed population: Opportunity for disease management?

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    Direct and indirect costs of nephrolithiasis in an employed population: Opportunity for disease management?BackgroundMore than 5% of the United States population has been diagnosed with nephrolithiasis and about one half of (first-time) stone formers will have a recurrence within 5 years. The prevalence of nephrolithiasis is concentrated among working age adults, yet little prior work has examined the economic burden of the disease on employers and their employees. We sought to estimate the direct and indirect costs of nephrolithiasis for working age adults (18-64) with employer-provided insurance.MethodsThis was an observational study using retrospective claims data. Detailed medical and pharmacy claims from 25 large employers and absentee data from a subset of firms were used to estimate the direct and indirect costs associated with nephrolithiasis in a privately insured, nonelderly population. Multivariate regression models were used to predict health care expenditures for persons with and without the condition, controlling for differences in patient (health status) and plan characteristics.ResultsMore than 1% of working-age adults were treated for nephrolithiasis in 2000. Prevalence was considerably higher among men and employees age 55 to 64. About one third of employees treated for nephrolithiasis in 2000 missed work due to the condition, with an average work loss for the entire treated population of 19 hours per person. Conditional on receiving treatment, the incremental costs of nephrolithiasis were $3,494 per person in 2000.ConclusionThe direct and indirect costs of nephrolithiaisis are substantial among working-age adults. Interventions that prevent recurrence among known stone formers may be a cost-effective component of disease management programs

    What Determines Adult Cognitive Skills? Impacts of Pre-Schooling, Schooling and Post-Schooling Experiences in Guatemala

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    Most investigations of the importance of and the determinants of adult cognitive skills assume that (a) they are produced primarily by schooling and (b) schooling is statistically predetermined. But these assumptions may lead to misleading inferences about impacts of schooling and of pre-schooling and post-schooling experiences on adult cognitive skills. This study uses an unusually rich longitudinal data set collected over 35 years in Guatemala to investigate production functions for adult (i) reading-comprehension and (ii) nonverbal cognitive skills as dependent on behaviorally-determined pre-schooling, schooling and post-schooling experiences. Major results are: (1) Schooling has significant and substantial impact on adult reading comprehension (but not on adult nonverbal cognitive skills)—but estimates of this impact are biased upwards substantially if there are no controls for behavioral determinants of schooling in the presence of persistent unobserved factors such as genetic endowments and/or if family background factors that appear to be correlated with genetic endowments are included among the first-stage instruments. (2) Both pre-schooling and post-schooling experiences have substantial significant impacts on one or both of the adult cognitive skill measures that tend to be underestimated if these pre- and post-schooling experiences are treated as statistically predetermined—in contrast to the upward bias for schooling, which suggests that the underlying physical and job-related components of genetic endowments are negatively correlated with those for cognitive skills. (3) The failure in most studies to incorporate pre- and post-schooling experiences in the analysis of adult cognitive skills or outcomes affected by adult cognitive skills is likely to lead to misleading over-emphasis on schooling relative to these pre-and post-schooling experiences. (4) Gender differences in the coefficients of the adult cognitive skills production functions are not significant, suggesting that most of the fairly substantial differences in adult cognitive skills favoring males on average originate from gender differences in schooling attainment and in experience in skilled jobs favoring males. These four sets of findings are of substantial interest in themselves. But they also have important implications for broader literatures, reinforcing the importance of early life investments in disadvantaged children in determining adult skills and options, pointing to limitations in the cross-country growth literature of using schooling of adults to represent human capital, supporting hypotheses about the importance of childhood nutrition and work complexity in explaining the “Flynn effect” of substantial increases in measured cognitive skills over time, and questioning the interpretation of studies that report productivity impacts of cognitive skills without controlling for the endogeneity of such skills.

    Parallel Evaluation of Multi-join Queries

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    A number of execution strategies for parallel evaluation of multi-join queries have been proposed in the literature. In this paper we give a comparative performance evaluation of four execution strategies by implementing all of them on the same parallel database system, PRISMA/DB. Experiments have been done up to 80 processors. These strategies, coming from the literature, are named: Sequential Parallel, Synchronous Execution, Segmented Right-Deep, and Full Parallel. Based on the experiments clear guidelines are given when to use which strategy. This is an extended abstract; the full paper appeared in Proc. ACM SIGMOD'94, Minneapolis, Minnesota, May 24–27, 199
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