Download or read book TSPA Model for the Yucca Mountain Unsaturated Zone written by and published by . This book was released on 2002 with total page 18 pages. Available in PDF, EPUB and Kindle. Book excerpt: Yucca Mountain, Nevada, is being considered as a potential site for a repository for spent nuclear fuel and high-level radioactive waste. Total-system performance-assessment (TSPA) calculations are performed to evaluate the safety of the site. Such calculations require submodels for all important engineered and natural components of the disposal system. There are five submodels related to the unsaturated zone: climate, infiltration, mountain-scale flow of water, seepage into emplacement drifts, and radionuclide transport. For each of these areas, models have been developed and implemented for use in TSPA. The climate model is very simple (a set of climate states have been deduced from paleoclimate data, and the times when climate changes occur in the future have been estimated), but the other four models make use of complex process models involving time-consuming computer runs. An important goal is to evaluate the impact of uncertainties (e.g., incomplete knowledge of the site) on the estimates of potential repository performance, so particular attention is given to the key uncertainties for each area. Uncertainties in climate, infiltration, and mountain-scale flow are represented in TSPA simulations by means of discrete high, medium, and low cases. Uncertainties in seepage and radionuclide transport are represented by means of continuous probability distributions for several key parameters.
Download or read book Recommendations for SZ TSPA Model Uncertainty Analysis Concerning the Yucca Mountain Project written by K. T. Bogen and published by . This book was released on 2003 with total page 19 pages. Available in PDF, EPUB and Kindle. Book excerpt: This report considers the problem of how best to evaluate the stability (i.e., sampling reliability) of Monte Carlo outputs obtained for two Yucca Mountain Project (YMP) modeling components, namely, outputs for the Saturated Zone (SZ) model, and for the Total System Performance Assessment (TSPA) model. One approach considered is the one that has been employed to date, namely, the application of Monte Carlo methods. Also considered in this context are potential improvements that might be obtained by the additional use of a Monte Carlo ''quitting rule'', such as that defined by Woo (1991), to select the number of Monte Carlo sample runs to perform. By the Monte Carlo approach, each output-value sample (realization) is calculated as a function of a sample-value vector of stochastic realizations, each of which in turn corresponds to a value of a corresponding distributed input variable. Abstractions from the SZ model and the Biosphere model are both used as input to the TSPA model. Sets of stochastic realizations required for SZ and TSPA abstractions ''expensive'' to generate, so the practical issue addressed by a ''quitting rule'' is how to determine what number of realizations is ''enough'' for the purpose of characterizing sampling error in the Monte Carlo estimate obtained for a specified model output of concern. In the TSPA context, the model output of concern is generally considered the time evolution of the arithmetic mean value, an estimator of the expected value, of TSPA-generated annual dose D(t) to the defined receptor within 10,000 y after waste-repository closure. Recommendations below specifically address: (1) whether or not a Monte Carlo approach (such as one employing the Woo quitting rule) is an appropriate basis for undertaking SZ- or TSPA-related uncertainty analysis, and (2) what other method might be more appropriate. While the following discussion and recommendations focus particularly on SZ applications, they also apply to other YMP model components including the TSPA. For this reason, some TSPA-specific issues are also addressed.
Download or read book Viability Assessment of a Repository at Yucca Mountain License application plan and costs written by and published by . This book was released on 1998 with total page 234 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book An International Peer Review of the Yucca Mountain Project TSPA SR written by OECD Nuclear Energy Agency and published by . This book was released on 2002 with total page 104 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Viability Assessment of a Repository at Yucca Mountain Volume 3 written by and published by . This book was released on 1998 with total page 525 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume reports the development of TSPA for the VA. This first section defines the general process involved in developing any TSPA, it describes the overall TSPA process as implemented by programs in the US and elsewhere in the world, and discusses the acceptability of TSPA as a process or tool for analyzing a nuclear waste repository system. Section 2 discusses the more specific use of the TSPA process for the TSPA-VA for Yucca Mountain, including goals, approach, and methods. It also includes a very brief synopsis of TSPA-VA results. Section 3 briefly discusses each of the component models that comprise the TSPA-VA. Each TSPA component model represents a discrete set of processes. The TSPA-VA components are: unsaturated zone flow, thermal hydrology, near- field geochemical environment, waste package degradation, waste form alteration and mobilization, unsaturated zone transport, saturated zone flow and transport, and biosphere. For each of these components, this section introduces the conceptualization of each individual process, describes the data sources, and discusses model parameter development and computer methods used to simulate each component. Section 4 explains the mechanics of how the individual TSPA components were combined into a ''base case'' and then provides the ''expected value'' results of a deterministic base case analysis. Section 4 also contains a description of the probabilistic analyses and results that help determine the relative importance of the various TSPA components and the data used to describe the components. Section 5 addresses sensitivity studies run for each of the TSPA components to understand how uncertainty in various parameters within a component change the TSPA results. Section 6 presents the findings of the sensitivity studies run on the various components in Section 5, and prioritizes the findings of the entire set of uncertainty and sensitivity studies of the components relative to each other. Section 6 also discusses the DOE assessment of potential activities to increase the confidence in future TSPAs based on the results of TSPA-VA, gives a synopsis of the insights provided by the TSPA Peer Review Panel, includes a discussion of comments received by DOE from NRC, and closes with concluding remarks.
Download or read book Viability Assessment of a Repository at Yucca Mountain Total system performance assessment written by and published by . This book was released on 1998 with total page 528 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Geotechnical Issues in Total System Performance Assessments of Yucca Mountain written by and published by . This book was released on 1999 with total page 72 pages. Available in PDF, EPUB and Kindle. Book excerpt: A Total System Performance Assessment (TSPA) of Yucca Mountain consists of integrated sub-models and analyses of natural and engineered systems. Examples of subsystem models include unsaturated-zone flow and transport, seepage into drifts, coupled thermal hydrologic processes, transport through the engineered barrier system, and saturated-zone flow and transport. The TSPA evaluates the interaction of important processes among these subsystems, and it determines the impact of these processes on the overall performance measures (e.g., dose rate to humans). This paper summarizes the evaluation, abstraction, and combination of these subsystem models in a TSPA calculation, and it provides background on the individual TSPA subsystem components that are most directly impacted by geotechnical issues. The potential impact that geologic features, events, and processes have on the overall performance is presented, and an evaluation of the sensitivity of TSPA calculations to these issues is also provided.
Download or read book Total system Performance Assessment for Yucca Mountain SNL Second Iteration TSPA 1993 written by and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Sandia National Laboratories has completed the second iteration of the periodic total-system performance assessments (TSPA-93) for the Yucca Mountain Site Characterization Project (YMP). These analyses estimate the future behavior of a potential repository for high-level nuclear waste at the Yucca Mountain, Nevada, site under consideration by the Department of Energy. TSPA-93 builds upon previous efforts by emphasizing YMP concerns relating to site characterization, design, and regulatory compliance. Scenarios describing expected conditions (aqueous and gaseous transport of contaminants) and low-probability events (human-intrusion drilling and volcanic intrusion) are modeled. The hydrologic processes modeled include estimates of the perturbations to ambient conditions caused by heating of the repository resulting from radioactive decay of the waste. Hydrologic parameters and parameter probability distributions have been derived from available site data. Possible future climate changes are modeled by considering two separate groundwater infiltration conditions: [open-quotes]wet[close-quotes] with a mean flux of 10 mm/yr, and [open-quotes]dry[close-quotes] with a mean flux of 0.5 mm/yr. Two alternative waste-package designs and two alternative repository areal thermal power densities are investigated. One waste package is a thin-wall container emplaced in a vertical borehole, and the second is a container designed with corrosion-resistant and corrosion-allowance walls emplaced horizontally in the drift. Thermal power loadings of 57 kW/acre (the loading specified in the original repository conceptual design) and 114 kW/acre (a loading chosen to investigate effects of a [open-quotes]hot repository[close-quotes]) are considered. TSPA-93 incorporates significant new detailed process modeling, including two- and three-dimensional modeling of thermal effects, groundwater flow in the saturated-zone aquifers, and gas flow in the unsaturated zone.
Download or read book Total system Performance Assessment for Yucca Mountain SNL Second Iteration TSPA 1993 Executive Summary written by and published by . This book was released on 1994 with total page 67 pages. Available in PDF, EPUB and Kindle. Book excerpt: Sandia National Laboratories has completed the second iteration of the periodic total-system performance assessments (TSPA-93) for the Yucca Mountain Site Characterization Project (YMP). Scenarios describing expected conditions (aqueous and gaseous transport of contaminants) and low-probability events (human-intrusion drilling and volcanic intrusion) are modeled. The hydrologic processes modeled include estimates of the perturbations to ambient conditions caused by heating of the repository resulting from radioactive decay of the waste. TSPA-93 incorporates significant new detailed process modeling, including two- and three-dimensional modeling of thermal effects, groundwater flow in the saturated-zone aquifers, and gas flow in the unsaturated zone. Probabilistic analyses are performed for aqueous and gaseous flow and transport, human intrusion, and basaltic magmatic activity. Results of the calculations lead to a number of recommendations concerning studies related to site characterization. Primary among these are the recommendations to obtain better information on percolation flux at Yucca Mountain, on the presence or absence of flowing fractures, and on physical and chemical processes influencing gaseous flow. Near-field thermal and chemical processes, and waste-container degradation are also areas where additional investigations may reduce important uncertainties. Recommendations for repository and waste-package design studies are: (1) to evaluate the performance implications of large-size containers, and (2) to investigate in more detail the implications of high repository thermal power output on the adjacent host rock and on the spent fuel.
Download or read book Biosphere Process Model Report written by and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: To evaluate the postclosure performance of a potential monitored geologic repository at Yucca Mountain, a Total System Performance Assessment (TSPA) will be conducted. Nine Process Model Reports (PMRs), including this document, are being developed to summarize the technical basis for each of the process models supporting the TSPA model. These reports cover the following areas: (1) Integrated Site Model; (2) Unsaturated Zone Flow and Transport; (3) Near Field Environment; (4) Engineered Barrier System Degradation, Flow, and Transport; (5) Waste Package Degradation; (6) Waste Form Degradation; (7) Saturated Zone Flow and Transport; (8) Biosphere; and (9) Disruptive Events. Analysis/Model Reports (AMRs) contain the more detailed technical information used to support TSPA and the PMRs. The AMRs consists of data, analyses, models, software, and supporting documentation that will be used to defend the applicability of each process model for evaluating the postclosure performance of the potential Yucca Mountain repository system. This documentation will ensure the traceability of information from its source through its ultimate use in the TSPA-Site Recommendation (SR) and in the National Environmental Policy Act (NEPA) analysis processes. The objective of the Biosphere PMR is to summarize (1) the development of the biosphere model, and (2) the Biosphere Dose Conversion Factors (BDCFs) developed for use in TSPA. The Biosphere PMR does not present or summarize estimates of potential radiation doses to human receptors. Dose calculations are performed as part of TSPA and will be presented in the TSPA documentation. The biosphere model is a component of the process to evaluate postclosure repository performance and regulatory compliance for a potential monitored geologic repository at Yucca Mountain, Nevada. The biosphere model describes those exposure pathways in the biosphere by which radionuclides released from a potential repository could reach a human receptor. Collectively, the potential human receptor and exposure pathways form the biosphere model. More detailed technical information and data about potential human receptor groups and the characteristics of exposure pathways have been developed in a series of AMRs and Calculation Reports.
Download or read book Development and Calibration of the Three Dimensional Site Scale Unsaturated Zone Model of Yucca Mountain Nevada written by and published by . This book was released on 1996 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Unsaturated Zone Flow Patterns and Analysis written by and published by . This book was released on 2001 with total page 211 pages. Available in PDF, EPUB and Kindle. Book excerpt: This Analysis/Model Report (AMR) documents the development of an expected-case model for unsaturated zone (UZ) flow and transport that will be described in terms of the representativeness of models of the natural system. The expected-case model will provide an evaluation of the effectiveness of the natural barriers, assess the impact of conservatism in the Total System Performance Assessment (TSPA), and support the development of further models and analyses for public confidence building. The present models used in ''Total System Performance Assessment for the Site Recommendation'' (Civilian Radioactive Waste Management System Management and Operating Contractor (CRWMS M & O) 2000 [1532461]) underestimate the natural-barrier performance because of conservative assumptions and parameters and do not adequately address uncertainty and alternative models. The development of an expected case model for the UZ natural barrier addresses issues regarding flow-pattern analysis and modeling that had previously been treated conservatively. This is in line with the Repository Safety Strategy (RSS) philosophy of treating conservatively those aspects of the UZ flow and transport system that are not important for achieving regulatory dose (CRWMS M & O 2000 [153246], Section 1.1.1). The development of an expected case model for the UZ also provides defense-in-depth in areas requiring further analysis of uncertainty and alternative models. In general, the value of the conservative case is to provide a more easily defensible TSPA for behavior of UZ flow and transport processes at Yucca Mountain. This AMR has been prepared in accordance with the ''Technical Work Plan for Unsaturated Zone (UZ) Flow and Transport Process Model Report'' (Bechtel SAIC Company (BSC) 2001 [155051], Section 1.3 - Work Package 4301213UMG). The work scope is to examine the data and current models of flow and transport in the Yucca Mountain UZ to identify models and analyses where conservatism may be reduced and uncertainty may be better characterized either through new analyses or development of new, alternative, models. This AMR supports Site Recommendation (SR) activities by documenting analyses and models reported in ''FY01 Supplemental Science and Performance Analyses, Volume 1: Scientific Bases and Analyses'' (BSC 2001 [155950]). However, except for the model results reported in Section 6.4.2, this AMR does not support TSPA as documented in either ''FY01 Supplemental Science and Performance Analyses, Volume 2: Performance Analyses'' (BSC 2001 [1546591]) or ''Total System Performance Assessment for the Site Recommendation'' (CRWMS M & O 2000 [153246]). Furthermore, this AMR represents scoping studies to aid in determining whether work beyond the scope of the models and analyses used to support TSPA-SR (CRWMS M & O 2000 [153246]) is warranted. If the decision is made to use any of these models and analyses for TSPA for License Application, further verification and validation will be required. The model results reported in Section 6.4.2 are used for TSPA sensitivity studies as documented in ''FY01 Supplemental Science and Performance Analyses, Volume 2: Performance Analyses'' (BSC 2001 [154659], Section 3.2.2.3).
Download or read book Yucca Mountain as a Radioactive waste Repository written by Thomas C. Hanks and published by . This book was released on 1999 with total page 32 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Viability Assessment written by and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume reports the development of TSPA for the VA. This first section defines the general process involved in developing any TSPA, it describes the overall TSPA process as implemented by programs in the US and elsewhere in the world, and discusses the acceptability of TSPA as a process or tool for analyzing a nuclear waste repository system. Section 2 discusses the more specific use of the TSPA process for the TSPA-VA for Yucca Mountain, including goals, approach, and methods. It also includes a very brief synopsis of TSPA-VA results. Section 3 briefly discusses each of the component models that comprise the TSPA-VA. Each TSPA component model represents a discrete set of processes. The TSPA-VA components are: unsaturated zone flow, thermal hydrology, near- field geochemical environment, waste package degradation, waste form alteration and mobilization, unsaturated zone transport, saturated zone flow and transport, and biosphere. For each of these components, this section introduces the conceptualization of each individual process, describes the data sources, and discusses model parameter development and computer methods used to simulate each component. Section 4 explains the mechanics of how the individual TSPA components were combined into a ''base case'' and then provides the ''expected value'' results of a deterministic base case analysis. Section 4 also contains a description of the probabilistic analyses and results that help determine the relative importance of the various TSPA components and the data used to describe the components. Section 5 addresses sensitivity studies run for each of the TSPA components to understand how uncertainty in various parameters within a component change the TSPA results. Section 6 presents the findings of the sensitivity studies run on the various components in Section 5, and prioritizes the findings of the entire set of uncertainty and sensitivity studies of the components relative to each other. Section 6 also discusses the DOE assessment of potential activities to increase the confidence in future TSPAs based on the results of TSPA-VA, gives a synopsis of the insights provided by the TSPA Peer Review Panel, includes a discussion of comments received by DOE from NRC, and closes with concluding remarks.
Download or read book Too Hot to Touch written by William M. Alley and published by Cambridge University Press. This book was released on 2013 with total page 385 pages. Available in PDF, EPUB and Kindle. Book excerpt: A fascinating and authoritative account of the controversies and possibilities surrounding nuclear waste disposal, providing expert discussion in down-to-earth language.
Download or read book Biblia magna Biblia cum concordantijs 1525 written by Jacques Mareschal and published by . This book was released on 1525 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt:
