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Dependence in probabilistic modeling, Dempster-Shafer theory, and probability bounds analysis.

Description: This report summarizes methods to incorporate information (or lack of information) about inter-variable dependence into risk assessments that use Dempster-Shafer theory or probability bounds analysis to address epistemic and aleatory uncertainty. The report reviews techniques for simulating correlated variates for a given correlation measure and dependence model, computation of bounds on distribution functions under a specified dependence model, formulation of parametric and empirical dependence models, and bounding approaches that can be used when information about the intervariable dependence is incomplete. The report also reviews several of the most pervasive and dangerous myths among risk analysts about dependence in probabilistic models.
Date: October 1, 2004
Creator: Oberkampf, William Louis; Tucker, W. Troy (Applied Biomathematics, Setauket, NY); Zhang, Jianzhong (Iowa State University, Ames, IA); Ginzburg, Lev (Applied Biomathematics, Setauket, NY); Berleant, Daniel J. (Iowa State University, Ames, IA); Ferson, Scott (Applied Biomathematics, Setauket, NY) et al.
Partner: UNT Libraries Government Documents Department
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A classification scheme for risk assessment methods.

Description: This report presents a classification scheme for risk assessment methods. This scheme, like all classification schemes, provides meaning by imposing a structure that identifies relationships. Our scheme is based on two orthogonal aspects--level of detail, and approach. The resulting structure is shown in Table 1 and is explained in the body of the report. Each cell in the Table represent a different arrangement of strengths and weaknesses. Those arrangements shift gradually as one moves through the table, each cell optimal for a particular situation. The intention of this report is to enable informed use of the methods so that a method chosen is optimal for a situation given. This report imposes structure on the set of risk assessment methods in order to reveal their relationships and thus optimize their usage.We present a two-dimensional structure in the form of a matrix, using three abstraction levels for the rows and three approaches for the columns. For each of the nine cells in the matrix we identify the method type by name and example. The matrix helps the user understand: (1) what to expect from a given method, (2) how it relates to other methods, and (3) how best to use it. Each cell in the matrix represent a different arrangement of strengths and weaknesses. Those arrangements shift gradually as one moves through the table, each cell optimal for a particular situation. The intention of this report is to enable informed use of the methods so that a method chosen is optimal for a situation given. The matrix, with type names in the cells, is introduced in Table 2 on page 13 below. Unless otherwise stated we use the word 'method' in this report to refer to a 'risk assessment method', though often times we use the full phrase. The use of the …
Date: August 1, 2004
Creator: Stamp, Jason Edwin & Campbell, Philip LaRoche
Partner: UNT Libraries Government Documents Department
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Environmental analysis of endocrine disrupting effects from hydrocarbon contaminants in the ecosystem. 1998 annual progress report

Description: 'The objective of this project is to determine how environmental contaminants, namely hydrocarbons, can act as hormones or anti-hormones (i.e., environmental hormones) in different species present in aquatic ecosystems. Species of particular focus are those which can serve as sentinel species (e.g., amphibians) and, thus, provide early warning signals for more widespread impacts on an ecosystem and its wildlife and human inhabitants. This reports the progress of 1.5 years of a three-year grant awarded to the Tulane/Xavier Center for Bioenvironmental Research (CBR). A growing body of evidence suggests that chemicals in the environment can disrupt the endocrine system of animals (i.e., wildlife and humans) and adversely impact the development of these species. Because of the multitude of known endocrine-disrupting chemicals and the numerous industrial and government sectors producing these chemicals, almost every federal agency has initiated research on the endocrine effects of chemicals relevant to their operations. This study represents the Department of Energy (DOE) Basic Energy Sciences'' only research on the impacts of endocrine-disrupting chemicals. The activities employed by this project to determine these impacts include development of biotechnology screens (in vitro), animal screens (in vivo), and other analyses of aquatic ecosystem biomarkers of exposure. The results from this study can elucidate how chemicals in the environment, including those from DOE activities, can signal (and alter) the development of a number of species in aquatic ecosystems. These signals can have detrimental impacts not only on an organismal level, but also on community, population, and entire ecosystem levels, including humans.'
Date: June 1, 1998
Creator: McLachlan, J.
Partner: UNT Libraries Government Documents Department
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Mechanism involved in trichloroethylene-induced liver cancer: Importance to environmental cleanup. 1997 annual progress report

Description: 'The Pacific Northwest National Lab. was awarded ten (10) Environmental Management Science Program (EMSP) research grants in Fiscal Year 1996. This section gives a summary of how each grant is addressing significant DOE cleanup issues, including those at the Hanford Site. The technical progress made to date in each of these research projects is addressed in more detail in the individual progress reports contained in this document. This research is primarily focused in three areas-Tank Waste Remediation, Soil and Groundwater Cleanup, and Health Effects.'
Date: June 1, 1997
Creator: Bull, R.J.
Partner: UNT Libraries Government Documents Department
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Environmentally-induced malignancies: An in vivo model to evaluate the health impact of chemicals in mixed waste. 1998 annual progress report

Description: 'Increased risk of malignancy following exposure to genotoxic agents in the environment is a major public concern. Exposure to radiation, benzene, and organic solvents is associated with an increased risk of leukemia; however the mechanism of leukemogenesis is unknown. The authors postulate that chemical(s) that increase the rate of genomic instability and induce hematotoxicity will promote accumulation of genetically-damaged hematopoietic stem cells (hsc), and thus contribute towards development of environmentally-induced hematologic malignancy. They will use molecular and cellular approaches to establish the relationship between hematoxicity, genomic instability and production of genetically aberrant hsc and progeny in mice exposed to radiation, benzene and trichloroethylene (TCE). The goals of this project are to (1) determine whether recruitment of hsc into cycle by agents that induce hematotoxicity (i.e., pancytopenia, anemia) facilitates fixation of genetic damage in hsc exposed to environmental genotoxins in vivo. (2) Determine whether environmental genotoxins with leukemogenic potential disrupt hsc genomic integrity by inactivating cell cycle checkpoints. (3) Determine whether low dose exposures to agents that induce chronic pancytopenia/anemia and/or cyclic hemopoiesis increase fixation of genetic damage in hsc. Increased understanding of the relationship between genotoxicity, hematotoxicity and genomic instability will (a) lend insight into mechanisms underlying environmental-induction of leukemic progression, (b) facilitate development of a rationale to identify chemical combinations which synergize to increase or decrease leukemogenic potential, and (c) provide opportunities to optimize approaches for biomonitoring and risk assessment. This report summarizes work after 1.5 year of a 3 year project. Accomplishments to-date include demonstration that the cycling status of hemopoietic stem cells at the time of genotoxin exposure alters the frequency and persistence of genetically damaged hemopoietic stem cells and associated progeny (Aim 1), development of assays to measure genomic instability in hemopoietic stem cells and associated progenitors (Aim 2) and quantification of genomically aberrant hsc and …
Date: June 1, 1998
Creator: Pallavicini, M.
Partner: UNT Libraries Government Documents Department
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Environmental analysis of endocrine disrupting effects from hydrocarbon contaminants in the ecosystem. 1997 annual progress report

Description: 'The overall objective of the basic research grant is to characterize the potential of common hydrocarbon contaminants in ecosystems to act as endocrine disruptors. The three major lines of research include (1) a biotechnology based screening system to identify potential hormone mimics and antagonists; (2) an animal screening system to identify biomarkers of endocrine effects. and (3) a literature review to identify compounds at a variety of DOE sites that need to be examined for endocrine disrupting effects. By relating results obtained from this research project to contamination problems at various DOE sites. CBR will provide data and information on endocrine disrupting contaminants to DOE for consideration in risk analyses for determining clean-up levels and priorities needed at the sites.'
Date: January 1, 1997
Partner: UNT Libraries Government Documents Department
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Environmentally-induced malignancies: An in vivo model to evaluate the health impact of chemicals in mixed waste. 1997 annual progress report

Description: 'Occupational or environmental exposure to organic ligands, solvents, fuel hydrocarbons, and polychlorinated biphenyls is linked to increased risk of developing leukemia, a blood cancer. The long term health effects of exposure to complex mixtures of chemicals and radionuclides are of particular concern because their biologic effects may synergize to increase risk of malignancy. Increased understanding of steps in the progression pathway of a normal cell to a cancer cell is important for biomonitoring, risk assessment and intervention in exposed individuals. Leukemias are characterized by multiple genetic aberrations. Accumulation of multiple genomic changes may reflect genomic instability in the affected ceils. Thus agents that induce DNA damage or genomic instability may increase accumulation of genomic alterations, thereby predisposing cells to transformation. However, not all DNA damaging agents predispose to transformation. Other factors such as genetic susceptibility, cell and tissue response to genotoxicity and cytotoxicity, DNA repair, etc. will impact malignant progression. The author proposed a progression model (Figure 1) of environmentally-induced leukemia that can be evaluated using mouse models.'
Date: January 1, 1997
Creator: Pallavicini, M.
Partner: UNT Libraries Government Documents Department
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Mechanism involved in trichloroethylene-induced liver cancer: Importance to environmental cleanup. 1998 annual progress report

Description: 'The objective of this project is to develop critical data for changing risk-based clean-up standards for trichloroethylene (TCE). The project is organized around two interrelated tasks: Task 1 addresses the tumorigenic and dosimetry issues for the metabolites of TCE that produce liver cancer in mice, dichloroacetate (DCA) and trichloroacetate (TCA). Early work had suggested that TCA was primarily responsible for TCE-induced liver tumors, but several, more mechanistic observations suggest that DCA may play a prominent role. This task is aimed at determining the basis for the selection hypothesis and seeks to prove that this mode of action is responsible for TCE-induced tumors. This project will supply the basic dose-response data from which low-dose extrapolations would be made. Task 2 seeks specific evidence that TCA and DCA are capable of promoting the growth of spontaneously initiated cells from mouse liver, in vitro. The data provide the clearest evidence that both metabolites act by a mechanism of selection rather than mutation. These data are necessary to select between a linear (i.e. no threshold) and non-linear low-dose extrapolation model. As of May of 1998, this research has identified two plausible modes of action by which TCE produces liver tumors in mice. These modes of action do not require the compounds to be mutagenic. The bulk of the experimental evidence suggests that neither TCE nor the two hepatocarcinogenic metabolites of TCE are mutagenic. The results from the colony formation assay clearly establish that both of these metabolites cause colony growth from initiated cells that occur spontaneously in the liver of B 6 C 3 F 1 mice, although the phenotypes of the colonies differ in the same manner as tumors differ, in vivo. In the case of DCA, a second mechanism may occur at a lower dose involving the release of insulin. This observation …
Date: June 1, 1998
Creator: Bull, R.J.; Thrall, B.D.; Sasser, L.B.; Miller, J.H. & Schultz, I.R.
Partner: UNT Libraries Government Documents Department
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Improved risk estimates for carbon tetrachloride. 1998 annual progress report

Description: 'The overall purpose of these studies is to improve the scientific basis for assessing the cancer risk associated with human exposure to carbon tetrachloride. Specifically, the toxicokinetics of inhaled carbon tetrachloride is being determined in rats, mice and hamsters. Species differences in the metabolism of carbon tetrachloride by rats, mice and hamsters is being determined in vivo and in vitro using tissues and microsomes from these rodent species and man. Dose-response relationships will be determined in all studies. The information will be used to improve the current physiologically based pharmacokinetic model for carbon tetrachloride. The authors will also determine whether carbon tetrachloride is a hepatocarcinogen only when exposure results in cell damage, cell killing, and regenerative cell proliferation. In combination, the results of these studies will provide the types of information needed to enable a refined risk estimate for carbon tetrachloride under EPA''s new guidelines for cancer risk assessment.'
Date: June 1, 1998
Creator: Benson, Janet M.; Springer, David L. & Thrall, Karla D.
Partner: UNT Libraries Government Documents Department
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An overview of the evolution of human reliability analysis in the context of probabilistic risk assessment.

Description: Since the Reactor Safety Study in the early 1970's, human reliability analysis (HRA) has been evolving towards a better ability to account for the factors and conditions that can lead humans to take unsafe actions and thereby provide better estimates of the likelihood of human error for probabilistic risk assessments (PRAs). The purpose of this paper is to provide an overview of recent reviews of operational events and advances in the behavioral sciences that have impacted the evolution of HRA methods and contributed to improvements. The paper discusses the importance of human errors in complex human-technical systems, examines why humans contribute to accidents and unsafe conditions, and discusses how lessons learned over the years have changed the perspective and approach for modeling human behavior in PRAs of complicated domains such as nuclear power plants. It is argued that it has become increasingly more important to understand and model the more cognitive aspects of human performance and to address the broader range of factors that have been shown to influence human performance in complex domains. The paper concludes by addressing the current ability of HRA to adequately predict human failure events and their likelihood.
Date: January 1, 2009
Creator: Bley, Dennis C. (Buttonwood Consulting Inc., Oakton, VA); Lois, Erasmia (U.S. Nuclear Regulatory Commission, Washington, DC); Kolaczkowski, Alan M. (Science Applications International Corporation, Eugene, OR); Forester, John Alan; Wreathall, John (John Wreathall and Co., Dublin, OH) & Cooper, Susan E. (U.S. Nuclear Regulatory Commission, Washington, DC)
Partner: UNT Libraries Government Documents Department
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Uncertainty Quantification in CO{sub 2} Sequestration Using Surrogate Models from Polynomial Chaos Expansion

Description: In this paper, surrogate models are iteratively built using polynomial chaos expansion (PCE) and detailed numerical simulations of a carbon sequestration system. Output variables from a numerical simulator are approximated as polynomial functions of uncertain parameters. Once generated, PCE representations can be used in place of the numerical simulator and often decrease simulation times by several orders of magnitude. However, PCE models are expensive to derive unless the number of terms in the expansion is moderate, which requires a relatively small number of uncertain variables and a low degree of expansion. To cope with this limitation, instead of using a classical full expansion at each step of an iterative PCE construction method, we introduce a mixed-integer programming (MIP) formulation to identify the best subset of basis terms in the expansion. This approach makes it possible to keep the number of terms small in the expansion. Monte Carlo (MC) simulation is then performed by substituting the values of the uncertain parameters into the closed-form polynomial functions. Based on the results of MC simulation, the uncertainties of injecting CO{sub 2} underground are quantified for a saline aquifer. Moreover, based on the PCE model, we formulate an optimization problem to determine the optimal CO{sub 2} injection rate so as to maximize the gas saturation (residual trapping) during injection, and thereby minimize the chance of leakage.
Date: April 6, 2013
Creator: Zhang, Yan & Sahinidis, Nikolaos V.
Partner: UNT Libraries Government Documents Department
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Abrupt Climate Change: Summary and Findings

Description: This report summary outlines brief answers to four questions about climate change. Will there be an abrupt change in sea level? Will there be an abrupt change in the hydrologic cycle? Will there be an abrupt change in the atlantic Meridional Overturning Circulation (AMOC)? Will there be abrupt change in atmospheric methane?
Date: 2008
Creator: Climate Change Science Program (U.S.)
Partner: UNT Libraries Government Documents Department
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Comparison of the bioavailability of elemental waste laden soils using in vivo and in vitro analytical methodology and refinement of exposure/dose models. 1998 annual progress report

Description: 'The authors hypotheses are: (1) the more closely the synthetic, in vitro, extractant mimics the extraction properties of the human digestive bio-fluids, the more accurate will be the estimate of an internal dose; (2) performance can be evaluated by in vivo studies with a rat model and quantitative examination of a mass balance, calculation and dose estimates from model simulations for the in vitro and in vivo system; and (3) the concentration of the elements Pb, Cd, Cr and selected Radionuclides present in the bioavailable fraction obtained with a synthetic extraction system will be a better indicator of contaminant ingestion from a contaminated soil because it represents the portion of the mass which can yield exposure, uptake and then the internal dose to an individual. As of April 15, 1998, they have made significant progress in the development of a unified approach to the examination of bioavailability and bioaccessibility of elemental contamination of soils for the ingestion route of exposure. This includes the initial characterization of the soil, in vitro measurements of bioaccessibility, and in vivo measurements of bioavailability. They have identified the basic chemical and microbiological characteristics of waste laden soils. These have been used to prioritize the soils for potential mobility of the trace elements present in the soil. Subsequently they have employed a mass balance technique, which for the first time tracked the movement and distribution of elements through an in vitro or in vivo experimental protocol to define the bioaccessible and the bioavailable fractions of digested soil. The basic mass balance equation for the in vitro system is: MT = MSGJ + MIJ + MR. where MT is the total mass extractable by a specific method, MSGJ, is the mass extracted by the saliva and the gastric juices, MIJ is the mass extracted by the intestinal …
Date: June 1, 1998
Creator: Lioy, P.J.; Gallo, M.; Georgopoulos, P.; Tate, R. & Buckley, B.
Partner: UNT Libraries Government Documents Department
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Development and application of the dynamic system doctor to nuclear reactor probabilistic risk assessments.

Description: This LDRD project has produced a tool that makes probabilistic risk assessments (PRAs) of nuclear reactors - analyses which are very resource intensive - more efficient. PRAs of nuclear reactors are being increasingly relied on by the United States Nuclear Regulatory Commission (U.S.N.R.C.) for licensing decisions for current and advanced reactors. Yet, PRAs are produced much as they were 20 years ago. The work here applied a modern systems analysis technique to the accident progression analysis portion of the PRA; the technique was a system-independent multi-task computer driver routine. Initially, the objective of the work was to fuse the accident progression event tree (APET) portion of a PRA to the dynamic system doctor (DSD) created by Ohio State University. Instead, during the initial efforts, it was found that the DSD could be linked directly to a detailed accident progression phenomenological simulation code - the type on which APET construction and analysis relies, albeit indirectly - and thereby directly create and analyze the APET. The expanded DSD computational architecture and infrastructure that was created during this effort is called ADAPT (Analysis of Dynamic Accident Progression Trees). ADAPT is a system software infrastructure that supports execution and analysis of multiple dynamic event-tree simulations on distributed environments. A simulator abstraction layer was developed, and a generic driver was implemented for executing simulators on a distributed environment. As a demonstration of the use of the methodological tool, ADAPT was applied to quantify the likelihood of competing accident progression pathways occurring for a particular accident scenario in a particular reactor type using MELCOR, an integrated severe accident analysis code developed at Sandia. (ADAPT was intentionally created with flexibility, however, and is not limited to interacting with only one code. With minor coding changes to input files, ADAPT can be linked to other such codes.) The …
Date: May 1, 2008
Creator: Kunsman, David Marvin; Aldemir, Tunc (Ohio State University); Rutt, Benjamin (Ohio State University); Metzroth, Kyle (Ohio State University); Catalyurek, Umit (Ohio State University); Denning, Richard (Ohio State University) et al.
Partner: UNT Libraries Government Documents Department
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The effects of emotional states and traits on risky decision-making.

Description: Understanding the role of emotional states is critical for predicting the kind of decisions people will make in risky situations. Currently, there is little understanding as to how emotion influences decision-making in situations such as terrorist attacks, natural disasters, pandemics, and combat. To help address this, we used behavioral and neuroimaging methods to examine how emotion states and traits influence decisions. Specifically, this study used a wheel of fortune behavioral task and functional magnetic resonance imaging (fMRI) to examine the effects of emotional states and traits on decision-making pertaining to the degree of risk people are willing to make in specific situations. The behavioral results are reported here. The neural data requires additional time to analyze and will be reported at a future date. Biases caused by emotion states and traits were found regarding the likelihood of making risky decisions. The behavioral results will help provide a solid empirical foundation for modeling the effects of emotion on decision in risky situations.
Date: December 1, 2006
Creator: Bernard, Michael Lewis & Smith, Bruce W., 1959- (,University of New Mexico, Albuquerque, NM-)
Partner: UNT Libraries Government Documents Department
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Development of Simplified Probabilistic Risk Assessment Model for Seismic Initiating Event

Description: ABSTRACT This paper discusses a simplified method to evaluate seismic risk using a methodology built on dividing the seismic intensity spectrum into multiple discrete bins. The seismic probabilistic risk assessment model uses Nuclear Regulatory Commission’s (NRC’s) full power Standardized Plant Analysis Risk (SPAR) model as the starting point for development. The seismic PRA models are integrated with their respective internal events at-power SPAR model. This is accomplished by combining the modified system fault trees from the full power SPAR model with seismic event tree logic. The peak ground acceleration is divided into five bins. The g-value for each bin is estimated using the geometric mean of lower and upper values of that particular bin and the associated frequency for each bin is estimated by taking the difference between upper and lower values of that bin. The component’s fragilities are calculated for each bin using the plant data, if available, or generic values of median peak ground acceleration and uncertainty values for the components. For human reliability analysis (HRA), the SPAR HRA (SPAR-H) method is used which requires the analysts to complete relatively straight forward worksheets that include the performance shaping factors (PSFs). The results are then used to estimate human error probabilities (HEPs) of interest. This work is expected to improve the NRC’s ability to include seismic hazards in risk assessments for operational events in support of the reactor oversight program (e.g., significance determination process).
Date: June 1, 2012
Creator: Khericha, S.; Buell, R.; Sancaktar, S.; Gonzalez, M. & Ferrante, F.
Partner: UNT Libraries Government Documents Department
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A novel biomarker for beryllium sensitization in humans. 1998 annual progress report

Description: 'Beryllium reactive T-lymphocytes can be used as an indicator of sensitization. Traditionally, their presence is detected by an in vitro proliferation assay. However, this test is capricious (results varying from day to day in the same laboratory) and insensitive (rarely positive before clinical symptoms ). The objective of this project is to obtain and characterize beryllium reactive T-cells from peripheral blood using the hprt T-cell mutation assay. T-cells are selected on the basis of their mutation of the hprt gene which renders them insensitive to 6-thioguanine in culture. Such mutant populations are expected to be enriched for cells which are proliferating in vivo as a result of the sensitizing process. This hypothesis has been verified in a number of studies. The seven specific aims of this study will: (i) identify the in vivo proliferating T-cell clones in sensitized individuals by selecting for hprt mutants, (ii) determine T-cell receptor (TCR) gene usages and commonalities among these clones, (iii) demonstrate reactivity to beryllium of these clones, (iv) generate beryllium sensitized T-cells in vitro from peripheral blood of the same individual, (v) determine TCR gene usages and commonalities for these in vitro derived cells, (vi) compare TCR gene patterns between the in vivo and in vitro derived clones, and (vii) develop a quantitative PCR (qPCR) method for amplifying the common (and therefore relevant) TCR genes directly from peripheral blood. The last of these is the novel biomarker of early beryllium sensitization. This report summarizes studies of the first 20 months of this project.'
Date: June 1, 1998
Creator: Albertini, R.J.
Partner: UNT Libraries Government Documents Department
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A novel biomarker for beryllium sensitization in humans. 1997 annual progress report

Description: 'Overall, this project is designed to identify the beryllium reactive T-cell clones that are proliferating in vivo in individuals sensitized to beryllium. The basic method for identifying such clones is the hprt T-cell mutation assay. The rationale is that in vivo proliferating T-lymphocytes are more likely to undergo hprt mutations and/or be included in hprt mutant fractions of T-cells isolated from peripheral blood. T-lymphocytes isolated as hprt mutants from beryllium sensitized individuals are propagated in vitro and characterized for T-cell receptor (TCR)/3 gene usage patterns and antigen reactivity. Results will be compared with similar characteristics determined for T-cell clones from the same individuals that were developed in vitro from peripheral blood lymphocytes by beryllium stimulation. This research project has several specific aims. Progress for the year 10/1/96 to 9/30/97 is given.'
Date: January 1, 1997
Creator: Albertini, R.J.
Partner: UNT Libraries Government Documents Department
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Risk-assessment methodology for fast breeder reactors

Description: The methods applied or proposed for risk assessment of nuclear reactors are reviewed, particularly with respect to their applicability for risk assessment of future commercial fast breeder reactors. All methods are based on the calculation of accident consequences for relatively few accident scenarios. The role and general impact of uncertainties in fast-reactor accident analysis are discussed. The discussion shows the need for improvement of the methodology. A generalized and improved risk-assessment methodology is outlined and proposed (accident-spectra-progression approach). The generalization consists primarily of an explicit treatment of uncertainties throughout the accident progression. The results of this method are obtained in form of consequence distributions. The width and shape of the distributions depend in part on the superposition of the uncertainties. The first moment of the consequence distribution gives an improved prediction of the ''average'' consequence. The higher-consequence moments can be used for consideration of risk aversion. The assessment of the risk of one or a certain number of nuclear reactors can only provide an ''isolated'' risk assessment. The general problem of safety risk assessment and its relation to public acceptance of certain modes of power production is a much broader problem area, which is also discussed.
Date: April 1976
Creator: Ott, Karl O.
Partner: UNT Libraries Government Documents Department
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Chemical analyses of soil samples collected from the vicinity of the thermal test complex at Sandia National Laboratories, New Mexico environs, 2006.

Description: In the summer of 2006, the Environmental Programs and Assurance Department of Sandia National Laboratories in Albuquerque, New Mexico (SNL/NM), collected surface soil samples at 37 locations within one mile of the vicinity of the newly constructed Thermal Test Complex (TTC) for the purpose of determining baseline conditions against which potential future impacts to the environs from operations at the facility could be assessed. These samples were submitted to an offsite analytical laboratory for metal-in-soil analyses. This work provided the SNL Environmental Programs and Assurance Department with a sound baseline data reference set against which to assess potential future operational impacts at the TTC. In addition, it demonstrates the commitment that the Laboratories have to go beyond mere compliance to achieve excellence in its operations. This data are presented in graphical format with narrative commentaries on particular items of interest.
Date: January 1, 2007
Creator: Miller, Mark Laverne & Nieto, Danielle M.
Partner: UNT Libraries Government Documents Department
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Probability of loss of assured safety in temperature dependent systems with multiple weak and strong links.

Description: Relationships to determine the probability that a weak link (WL)/strong link (SL) safety system will fail to function as intended in a fire environment are investigated. In the systems under study, failure of the WL system before failure of the SL system is intended to render the overall system inoperational and thus prevent the possible occurrence of accidents with potentially serious consequences. Formal developments of the probability that the WL system fails to deactivate the overall system before failure of the SL system (i.e., the probability of loss of assured safety, PLOAS) are presented for several WWSL configurations: (i) one WL, one SL, (ii) multiple WLs, multiple SLs with failure of any SL before any WL constituting failure of the safety system, (iii) multiple WLs, multiple SLs with failure of all SLs before any WL constituting failure of the safety system, and (iv) multiple WLs, multiple SLs and multiple sublinks in each SL with failure of any sublink constituting failure of the associated SL and failure of all SLs before failure of any WL constituting failure of the safety system. The indicated probabilities derive from time-dependent temperatures in the WL/SL system and variability (i.e., aleatory uncertainty) in the temperatures at which the individual components of this system fail and are formally defined as multidimensional integrals. Numerical procedures based on quadrature (i.e., trapezoidal rule, Simpson's rule) and also on Monte Carlo techniques (i.e., simple random sampling, importance sampling) are described and illustrated for the evaluation of these integrals. Example uncertainty and sensitivity analyses for PLOAS involving the representation of uncertainty (i.e., epistemic uncertainty) with probability theory and also with evidence theory are presented.
Date: December 1, 2004
Creator: Johnson, Jay Dean (ProStat, Mesa, AZ); Oberkampf, William Louis & Helton, Jon Craig (Arizona State University, Tempe, AZ)
Partner: UNT Libraries Government Documents Department
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Cancer Risk Assessment: Should New Science be Applied? Workgroup summary

Description: OAK-B135 A symposium discussing the implications of certain phenomena observed in radiation biology for cancer risk assessment in general. In July of 2002 a workshop was convened that explored some of the intercellular phenomena that appear to condition responses to carcinogen exposure. Effects that result from communication between cells that appear to either increase the sphere of damage or to modify the sensitivity of cells to further damage were of particular interest. Much of the discussion focused on the effects of ionizing radiation that were transmitted from cells directly hit to cells not receiving direct exposure to radiation (bystander cells). In cell culture, increased rates of mutation, chromosomal aberration, apoptosis, genomic instability, and decreased clonogenic survival have all been observed in cells that have experienced no direct radiation. In addition, there is evidence that low doses of radiation or certain chemicals give rise to adaptive responses in which the treated cells develop resistance to the effects of high doses given in subsequent exposures. Data were presented at the workshop indicating that low dose exposure of animals to radiation and some chemicals frequently reduces the spontaneous rate of mutation in vitro and tumor responses in vivo. Finally, it was concluded that considerable improvement in understanding of how genetic variation may modify the impact of these phenomena is necessary before the risk implications can be fully appreciated. The workshop participants discussed the substantive challenge that these data present with respect to simple linear methodologies that are currently used in cancer risk assessment and attempted to identify broad strategies by which these phenomena may start to be used to refine cancer risk assessment methods in the future.
Date: December 15, 2002
Creator: Bull, Richard J. & Brooks, Antone L.
Partner: UNT Libraries Government Documents Department
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Behavior of Irradiated Metallic Fuel Elements Exposed to Nuclear Excursion in TREAT

Description: In fast reactor safety studies, it is imperative to know the effects of temperature excursions on the fuel elements. Previous controlled out-of-pile experiments on the behavior of uranium fuel elements under meltdown or near-meltdown conditions have been performed using direct electrical resistance heating or furnace heating. As a step toward obtaining more complete information on reactivity effects accompanying fuel meltdown, the behavior of irradiated EBR II and Fermi A samples under transient nuclear heating in TREAT has been studied. The experiment results obtained indicate that effects of prior irradiation can produce significant effects upon reactivity changes produced by meltdown of metallic fast reactor fuel pins.
Date: November 1963
Creator: Monaweck, J. H.; Dickerman, Charles Edward, 1932- & Sowa, E. S.
Partner: UNT Libraries Government Documents Department
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