Uncertainty Quantification in the Reliability and Risk Assessment of Generation IV Reactors: Final Scientific/Technical Report

International Nuclear Information System (INIS)

Vierow, Karen; Aldemir, Tunc

2009-01-01

The project entitled, 'Uncertainty Quantification in the Reliability and Risk Assessment of Generation IV Reactors', was conducted as a DOE NERI project collaboration between Texas A and M University and The Ohio State University between March 2006 and June 2009. The overall goal of the proposed project was to develop practical approaches and tools by which dynamic reliability and risk assessment techniques can be used to augment the uncertainty quantification process in probabilistic risk assessment (PRA) methods and PRA applications for Generation IV reactors. This report is the Final Scientific/Technical Report summarizing the project.

Uncertainty Quantification in the Reliability and Risk Assessment of Generation IV Reactors: Final Scientific/Technical Report

Energy Technology Data Exchange (ETDEWEB)

Vierow, Karen; Aldemir, Tunc

2009-09-10

The project entitled, “Uncertainty Quantification in the Reliability and Risk Assessment of Generation IV Reactors”, was conducted as a DOE NERI project collaboration between Texas A&M University and The Ohio State University between March 2006 and June 2009. The overall goal of the proposed project was to develop practical approaches and tools by which dynamic reliability and risk assessment techniques can be used to augment the uncertainty quantification process in probabilistic risk assessment (PRA) methods and PRA applications for Generation IV reactors. This report is the Final Scientific/Technical Report summarizing the project.

Effect of standardized training on the reliability of the Cochrane risk of bias assessment tool: a prospective study.

Science.gov (United States)

da Costa, Bruno R; Beckett, Brooke; Diaz, Alison; Resta, Nina M; Johnston, Bradley C; Egger, Matthias; Jüni, Peter; Armijo-Olivo, Susan

2017-03-03

The Cochrane risk of bias tool is commonly criticized for having a low reliability. We aimed to investigate whether training of raters, with objective and standardized instructions on how to assess risk of bias, can improve the reliability of the Cochrane risk of bias tool. In this pilot study, four raters inexperienced in risk of bias assessment were randomly allocated to minimal or intensive standardized training for risk of bias assessment of randomized trials of physical therapy treatments for patients with knee osteoarthritis pain. Two raters were experienced risk of bias assessors who served as reference. The primary outcome of our study was between-group reliability, defined as the agreement of the risk of bias assessments of inexperienced raters with the reference assessments of experienced raters. Consensus-based assessments were used for this purpose. The secondary outcome was within-group reliability, defined as the agreement of assessments within pairs of inexperienced raters. We calculated the chance-corrected weighted Kappa to quantify agreement within and between groups of raters for each of the domains of the risk of bias tool. A total of 56 trials were included in our analysis. The Kappa for the agreement of inexperienced raters with reference across items of the risk of bias tool ranged from 0.10 to 0.81 for the minimal training group and from 0.41 to 0.90 for the standardized training group. The Kappa values for the agreement within pairs of inexperienced raters across the items of the risk of bias tool ranged from 0 to 0.38 for the minimal training group and from 0.93 to 1 for the standardized training group. Between-group differences in Kappa for the agreement of inexperienced raters with reference always favored the standardized training group and was most pronounced for incomplete outcome data (difference in Kappa 0.52, p training on risk of bias assessment may significantly improve the reliability of the Cochrane risk of bias tool.

Systems reliability in high risk situations

International Nuclear Information System (INIS)

Hunns, D.M.

1974-12-01

A summary is given of five papers and the discussion of a seminar promoted by the newly-formed National Centre of Systems Reliability. The topics covered include hazard analysis, reliability assessment, and risk assessment in both nuclear and non-nuclear industries. (U.K.)

Methodology for allocating reliability and risk

International Nuclear Information System (INIS)

Cho, N.Z.; Papazoglou, I.A.; Bari, R.A.

1986-05-01

This report describes a methodology for reliability and risk allocation in nuclear power plants. The work investigates the technical feasibility of allocating reliability and risk, which are expressed in a set of global safety criteria and which may not necessarily be rigid, to various reactor systems, subsystems, components, operations, and structures in a consistent manner. The report also provides general discussions on the problem of reliability and risk allocation. The problem is formulated as a multiattribute decision analysis paradigm. The work mainly addresses the first two steps of a typical decision analysis, i.e., (1) identifying alternatives, and (2) generating information on outcomes of the alternatives, by performing a multiobjective optimization on a PRA model and reliability cost functions. The multiobjective optimization serves as the guiding principle to reliability and risk allocation. The concept of ''noninferiority'' is used in the multiobjective optimization problem. Finding the noninferior solution set is the main theme of the current approach. The final step of decision analysis, i.e., assessment of the decision maker's preferences could then be performed more easily on the noninferior solution set. Some results of the methodology applications to a nontrivial risk model are provided, and several outstanding issues such as generic allocation, preference assessment, and uncertainty are discussed. 29 refs., 44 figs., 39 tabs

Effect of standardized training on the reliability of the Cochrane risk of bias assessment tool: a study protocol.

Science.gov (United States)

da Costa, Bruno R; Resta, Nina M; Beckett, Brooke; Israel-Stahre, Nicholas; Diaz, Alison; Johnston, Bradley C; Egger, Matthias; Jüni, Peter; Armijo-Olivo, Susan

2014-12-13

The Cochrane risk of bias (RoB) tool has been widely embraced by the systematic review community, but several studies have reported that its reliability is low. We aim to investigate whether training of raters, including objective and standardized instructions on how to assess risk of bias, can improve the reliability of this tool. We describe the methods that will be used in this investigation and present an intensive standardized training package for risk of bias assessment that could be used by contributors to the Cochrane Collaboration and other reviewers. This is a pilot study. We will first perform a systematic literature review to identify randomized clinical trials (RCTs) that will be used for risk of bias assessment. Using the identified RCTs, we will then do a randomized experiment, where raters will be allocated to two different training schemes: minimal training and intensive standardized training. We will calculate the chance-corrected weighted Kappa with 95% confidence intervals to quantify within- and between-group Kappa agreement for each of the domains of the risk of bias tool. To calculate between-group Kappa agreement, we will use risk of bias assessments from pairs of raters after resolution of disagreements. Between-group Kappa agreement will quantify the agreement between the risk of bias assessment of raters in the training groups and the risk of bias assessment of experienced raters. To compare agreement of raters under different training conditions, we will calculate differences between Kappa values with 95% confidence intervals. This study will investigate whether the reliability of the risk of bias tool can be improved by training raters using standardized instructions for risk of bias assessment. One group of inexperienced raters will receive intensive training on risk of bias assessment and the other will receive minimal training. By including a control group with minimal training, we will attempt to mimic what many review authors

Structural reliability assessment capability in NESSUS

Science.gov (United States)

Millwater, H.; Wu, Y.-T.

1992-07-01

The principal capabilities of NESSUS (Numerical Evaluation of Stochastic Structures Under Stress), an advanced computer code developed for probabilistic structural response analysis, are reviewed, and its structural reliability assessed. The code combines flexible structural modeling tools with advanced probabilistic algorithms in order to compute probabilistic structural response and resistance, component reliability and risk, and system reliability and risk. An illustrative numerical example is presented.

Analysis of dependent failures in risk assessment and reliability evaluation

International Nuclear Information System (INIS)

Fleming, K.N.; Mosleh, A.; Kelley, A.P. Jr.; Gas-Cooled Reactors Associates, La Jolla, CA)

1983-01-01

The ability to estimate the risk of potential reactor accidents is largely determined by the ability to analyze statistically dependent multiple failures. The importance of dependent failures has been indicated in recent probabilistic risk assessment (PRA) studies as well as in reports of reactor operating experiences. This article highlights the importance of several different types of dependent failures from the perspective of the risk and reliability analyst and provides references to the methods and data available for their analysis. In addition to describing the current state of the art, some recent advances, pitfalls, misconceptions, and limitations of some approaches to dependent failure analysis are addressed. A summary is included of the discourse on this subject, which is presented in the Institute of Electrical and Electronics Engineers/American Nuclear Society PRA Procedures Guide

Investigating the reliability and validity of the waterlow risk assessment scale: a literature review.

LENUS (Irish Health Repository)

Walsh, Breda

2012-02-01

The aim of this review was to examine health literature on the reliability and validity of the Waterlow pressure sore assessment scale. A systematic review of published studies relating to the topic was conducted and literature was examined for its relevancy to the topic under investigation. Findings suggest that despite the availability of over 40 assessment tools, the Waterlow assessment scale is the most frequently used by health care staff. Research suggests that the Waterlow Scale is an unreliable method of assessing individuals at risk of pressure sore development with all studies indicating a poor interrater reliability status. Its validity has also been criticized because of its high-sensitivity but low-specificity levels.

Investigating the reliability and validity of the waterlow risk assessment scale: a literature review.

LENUS (Irish Health Repository)

Walsh, Breda

2011-05-01

The aim of this review was to examine health literature on the reliability and validity of the Waterlow pressure sore assessment scale. A systematic review of published studies relating to the topic was conducted and literature was examined for its relevancy to the topic under investigation. Findings suggest that despite the availability of over 40 assessment tools, the Waterlow assessment scale is the most frequently used by health care staff. Research suggests that the Waterlow Scale is an unreliable method of assessing individuals at risk of pressure sore development with all studies indicating a poor interrater reliability status. Its validity has also been criticized because of its high-sensitivity but low-specificity levels.

Methodology for risk assessment and reliability applied for pipeline engineering design and industrial valves operation

Energy Technology Data Exchange (ETDEWEB)

Silveira, Dierci [Universidade Federal Fluminense (UFF), Volta Redonda, RJ (Brazil). Escola de Engenharia Industrial e Metalurgia. Lab. de Sistemas de Producao e Petroleo e Gas], e-mail: dsilveira@metal.eeimvr.uff.br; Batista, Fabiano [CICERO, Rio das Ostras, RJ (Brazil)

2009-07-01

Two kinds of situations may be distinguished for estimating the operating reliability when maneuvering industrial valves and the probability of undesired events in pipelines and industrial plants: situations in which the risk is identified in repetitive cycles of operations and situations in which there is a permanent hazard due to project configurations introduced by decisions during the engineering design definition stage. The estimation of reliability based on the influence of design options requires the choice of a numerical index, which may include a composite of human operating parameters based on biomechanics and ergonomics data. We first consider the design conditions under which the plant or pipeline operator reliability concepts can be applied when operating industrial valves, and then describe in details the ergonomics and biomechanics risks that would lend itself to engineering design database development and human reliability modeling and assessment. This engineering design database development and reliability modeling is based on a group of engineering design and biomechanics parameters likely to lead to over-exertion forces and working postures, which are themselves associated with the functioning of a particular plant or pipeline. This approach to construct based on ergonomics and biomechanics for a more common industrial valve positioning in the plant layout is proposed through the development of a methodology to assess physical efforts and operator reach, combining various elementary operations situations. These procedures can be combined with the genetic algorithm modeling and four elements of the man-machine systems: the individual, the task, the machinery and the environment. The proposed methodology should be viewed not as competing to traditional reliability and risk assessment bur rather as complementary, since it provides parameters related to physical efforts values for valves operation and workspace design and usability. (author)

A shortened version of the THERP/Handbook approach to human reliability analysis for probabilistic risk assessment

International Nuclear Information System (INIS)

Swain, A.D.

1986-01-01

The approach to human reliability analysis (HRA) known as THERP/Handbook has been applied to several probabilistic risk assessments (PRAs) of nuclear power plants (NPPs) and other complex systems. The approach is based on a thorough task analysis of the man-machine interfaces, including the interactions among the people, involved in the operations being assessed. The idea is to assess fully the underlying performance shaping factors (PSFs) and dependence effects which result either in reliable or unreliable human performance

A Closed-Form Technique for the Reliability and Risk Assessment of Wind Turbine Systems

Directory of Open Access Journals (Sweden)

Leonardo Dueñas-Osorio

2012-06-01

Full Text Available This paper proposes a closed-form method to evaluate wind turbine system reliability and associated failure consequences. Monte Carlo simulation, a widely used approach for system reliability assessment, usually requires large numbers of computational experiments, while existing analytical methods are limited to simple system event configurations with a focus on average values of reliability metrics. By analyzing a wind turbine system and its components in a combinatorial yet computationally efficient form, the proposed approach provides an entire probability distribution of system failure that contains all possible configurations of component failure and survival events. The approach is also capable of handling unique component attributes such as downtime and repair cost needed for risk estimations, and enables sensitivity analysis for quantifying the criticality of individual components to wind turbine system reliability. Applications of the technique are illustrated by assessing the reliability of a 12-subassembly turbine system. In addition, component downtimes and repair costs of components are embedded in the formulation to compute expected annual wind turbine unavailability and repair cost probabilities, and component importance metrics useful for maintenance planning and research prioritization. Furthermore, this paper introduces a recursive solution to closed-form method and applies this to a 45-component turbine system. The proposed approach proves to be computationally efficient and yields vital reliability information that could be readily used by wind farm stakeholders for decision making and risk management.

Bayesian Inference for NASA Probabilistic Risk and Reliability Analysis

Science.gov (United States)

Dezfuli, Homayoon; Kelly, Dana; Smith, Curtis; Vedros, Kurt; Galyean, William

2009-01-01

This document, Bayesian Inference for NASA Probabilistic Risk and Reliability Analysis, is intended to provide guidelines for the collection and evaluation of risk and reliability-related data. It is aimed at scientists and engineers familiar with risk and reliability methods and provides a hands-on approach to the investigation and application of a variety of risk and reliability data assessment methods, tools, and techniques. This document provides both: A broad perspective on data analysis collection and evaluation issues. A narrow focus on the methods to implement a comprehensive information repository. The topics addressed herein cover the fundamentals of how data and information are to be used in risk and reliability analysis models and their potential role in decision making. Understanding these topics is essential to attaining a risk informed decision making environment that is being sought by NASA requirements and procedures such as 8000.4 (Agency Risk Management Procedural Requirements), NPR 8705.05 (Probabilistic Risk Assessment Procedures for NASA Programs and Projects), and the System Safety requirements of NPR 8715.3 (NASA General Safety Program Requirements).

Assessments and applications to enhance human reliability and reduce risk during less-than-full-power operations

International Nuclear Information System (INIS)

Hannaman, G.W.; Singh, A.

1992-01-01

Study of events, interviews with plant personnel, and applications of risk studies indicate that the risk of a potential accident during less-than-full-power (LTFP) operation is becoming a greater fraction of the risk as improvements are made to the full-power operations. Industry efforts have been increased to reduce risk and the cost of shutdown operations. These efforts consider the development and application of advanced tools to help utilities proactively identify issues and develop contingencies and interventions to enhance reliability and reduce risk of low-power operations at nuclear power plants. The role for human reliability assessments is to help improve utility outage planning to better achieve schedule and risk control objectives. Improvements are expected to include intervention tools to identify and reduce human error, definition of new instructional modules, and prioritization of risk reduction issues for operators. The Electric Power Research Institute is sponsoring a project to address the identification and quantification of factors that affect human reliability during LTFP operation of nuclear power plants. The results of this project are expected to promote the development of proactively applied interventions and contingencies for enhanced human reliability during shutdown operations

Inter-rater reliability of the German version of the Nurses' Global Assessment of Suicide Risk scale.

Science.gov (United States)

Kozel, Bernd; Grieser, Manuela; Abderhalden, Christoph; Cutcliffe, John R

2016-10-01

In comparison to the general population, the suicide rates of psychiatric inpatient populations in Germany and Switzerland are very high. An important preventive contribution to the lowering of the suicide rates in mental health care is to ensure that the risk of suicide of psychiatric inpatients is assessed as accurately as possible. While risk-assessment instruments can serve an important function in determining such risk, very few have been translated to German. Therefore, in the present study, we reported on the German version of Nurses' Global Assessment of Suicide Risk (NGASR) scale. After translating the original instrument into German and pretesting the German version, we tested the inter-rater reliability of the instrument. Twelve video case studies were evaluated by 13 raters with the NGASR scale in a 'laboratory' trial. In each case, the observer's agreement was calculated for the single items, the overall scale, the risk levels, and the sum scores. The statistical data analysis was conducted with kappa and AC1 statistics for dichotomous (items, scale) scales. A high-to-very high observers' agreement (AC1: 0.62-1.00, kappa: 0.00-1.00) was determined for 16 items of the German version of the NGASR scale. We conclude that the German version of the NGASR scale is a reliable instrument for evaluating risk factors for suicide. A reliable application in the clinical practise appears to be enhanced by training in the use of the instrument and the right implementation instructions. © 2016 Australian College of Mental Health Nurses Inc.

A framework for reliability and risk centered maintenance

International Nuclear Information System (INIS)

Selvik, J.T.; Aven, T.

2011-01-01

Reliability centered maintenance (RCM) is a well-established analysis method for preventive maintenance planning. As its name indicates, reliability is the main point of reference for the planning, but consequences of failures are also assessed. However, uncertainties and risk are to a limited extent addressed by the RCM method, and in this paper we suggest an extension of the RCM to reliability and risk centered maintenance (RRCM) by also considering risk as the reference for the analysis in addition to reliability. A broad perspective on risk is adopted where uncertainties are the main component of risk in addition to possible events and associated consequences. A case from the offshore oil and gas industry is presented to illustrate and discuss the suggested approach.

Quantified Risk Ranking Model for Condition-Based Risk and Reliability Centered Maintenance

Science.gov (United States)

Chattopadhyaya, Pradip Kumar; Basu, Sushil Kumar; Majumdar, Manik Chandra

2017-06-01

In the recent past, risk and reliability centered maintenance (RRCM) framework is introduced with a shift in the methodological focus from reliability and probabilities (expected values) to reliability, uncertainty and risk. In this paper authors explain a novel methodology for risk quantification and ranking the critical items for prioritizing the maintenance actions on the basis of condition-based risk and reliability centered maintenance (CBRRCM). The critical items are identified through criticality analysis of RPN values of items of a system and the maintenance significant precipitating factors (MSPF) of items are evaluated. The criticality of risk is assessed using three risk coefficients. The likelihood risk coefficient treats the probability as a fuzzy number. The abstract risk coefficient deduces risk influenced by uncertainty, sensitivity besides other factors. The third risk coefficient is called hazardous risk coefficient, which is due to anticipated hazards which may occur in the future and the risk is deduced from criteria of consequences on safety, environment, maintenance and economic risks with corresponding cost for consequences. The characteristic values of all the three risk coefficients are obtained with a particular test. With few more tests on the system, the values may change significantly within controlling range of each coefficient, hence `random number simulation' is resorted to obtain one distinctive value for each coefficient. The risk coefficients are statistically added to obtain final risk coefficient of each critical item and then the final rankings of critical items are estimated. The prioritization in ranking of critical items using the developed mathematical model for risk assessment shall be useful in optimization of financial losses and timing of maintenance actions.

Validity and Reliability of Persian Version of Johns Hopkins Fall Risk Assessment Tool among Aged People

Directory of Open Access Journals (Sweden)

hadi hojati

2018-04-01

Full Text Available Background & Aim: It is crucial to identify aged patients in risk of falls in clinical settings. Johns Hopkins Fall Risk Assessment Tool (JHFRAT is one of most applied international instrument to assess elderly patients for the risk of falls. The aim of this study was to evaluate reliability and internal consistency of the JHFRAT. Methods & Materials: In this cross-sectional study for validity assessment of the tool, WHO’s standard protocol was applied for translation-back translation of the tool. Face and content validity of the tool was confirmed by ten person of expert faculty members for its applicability in clinical setting. In this pilot study, the inclusion criteria were being 60 or more years old, hospitalized in the last 8 hours prior to assessment and in proper cognitive condition assessed by MMSE. Subjects of the study were (n=70 elderly patients who were newly hospitalized in Shahroud Emam Hossein Hospital. Data were analyzed using SPSS software- version 16. Internal consistency of the tool was calculated by Cronbach’s alpha. Results: According to the results of the study Persian version of JHFRAT was a valid tool for application on clinical setting. The Persian version of the tool had Cronbach’s alpha equal to 0/733. Conclusion: Based on the findings of the current study, it can be concluded that Persian version of the JHFRAT is a valid and reliable tool to be applied for assessment of elderly senior citizens on admission in any clinical settings.

Complex method to calculate objective assessments of information systems protection to improve expert assessments reliability

Science.gov (United States)

Abdenov, A. Zh; Trushin, V. A.; Abdenova, G. A.

2018-01-01

The paper considers the questions of filling the relevant SIEM nodes based on calculations of objective assessments in order to improve the reliability of subjective expert assessments. The proposed methodology is necessary for the most accurate security risk assessment of information systems. This technique is also intended for the purpose of establishing real-time operational information protection in the enterprise information systems. Risk calculations are based on objective estimates of the adverse events implementation probabilities, predictions of the damage magnitude from information security violations. Calculations of objective assessments are necessary to increase the reliability of the proposed expert assessments.

Results of a Demonstration Assessment of Passive System Reliability Utilizing the Reliability Method for Passive Systems (RMPS)

Energy Technology Data Exchange (ETDEWEB)

Bucknor, Matthew; Grabaskas, David; Brunett, Acacia; Grelle, Austin

2015-04-26

Advanced small modular reactor designs include many advantageous design features such as passively driven safety systems that are arguably more reliable and cost effective relative to conventional active systems. Despite their attractiveness, a reliability assessment of passive systems can be difficult using conventional reliability methods due to the nature of passive systems. Simple deviations in boundary conditions can induce functional failures in a passive system, and intermediate or unexpected operating modes can also occur. As part of an ongoing project, Argonne National Laboratory is investigating various methodologies to address passive system reliability. The Reliability Method for Passive Systems (RMPS), a systematic approach for examining reliability, is one technique chosen for this analysis. This methodology is combined with the Risk-Informed Safety Margin Characterization (RISMC) approach to assess the reliability of a passive system and the impact of its associated uncertainties. For this demonstration problem, an integrated plant model of an advanced small modular pool-type sodium fast reactor with a passive reactor cavity cooling system is subjected to a station blackout using RELAP5-3D. This paper discusses important aspects of the reliability assessment, including deployment of the methodology, the uncertainty identification and quantification process, and identification of key risk metrics.

Parts and Components Reliability Assessment: A Cost Effective Approach

Science.gov (United States)

Lee, Lydia

2009-01-01

System reliability assessment is a methodology which incorporates reliability analyses performed at parts and components level such as Reliability Prediction, Failure Modes and Effects Analysis (FMEA) and Fault Tree Analysis (FTA) to assess risks, perform design tradeoffs, and therefore, to ensure effective productivity and/or mission success. The system reliability is used to optimize the product design to accommodate today?s mandated budget, manpower, and schedule constraints. Stand ard based reliability assessment is an effective approach consisting of reliability predictions together with other reliability analyses for electronic, electrical, and electro-mechanical (EEE) complex parts and components of large systems based on failure rate estimates published by the United States (U.S.) military or commercial standards and handbooks. Many of these standards are globally accepted and recognized. The reliability assessment is especially useful during the initial stages when the system design is still in the development and hard failure data is not yet available or manufacturers are not contractually obliged by their customers to publish the reliability estimates/predictions for their parts and components. This paper presents a methodology to assess system reliability using parts and components reliability estimates to ensure effective productivity and/or mission success in an efficient manner, low cost, and tight schedule.

Modeling and Quantification of Team Performance in Human Reliability Analysis for Probabilistic Risk Assessment

Energy Technology Data Exchange (ETDEWEB)

Jeffrey C. JOe; Ronald L. Boring

2014-06-01

Probabilistic Risk Assessment (PRA) and Human Reliability Assessment (HRA) are important technical contributors to the United States (U.S.) Nuclear Regulatory Commission’s (NRC) risk-informed and performance based approach to regulating U.S. commercial nuclear activities. Furthermore, all currently operating commercial NPPs in the U.S. are required by federal regulation to be staffed with crews of operators. Yet, aspects of team performance are underspecified in most HRA methods that are widely used in the nuclear industry. There are a variety of "emergent" team cognition and teamwork errors (e.g., communication errors) that are 1) distinct from individual human errors, and 2) important to understand from a PRA perspective. The lack of robust models or quantification of team performance is an issue that affects the accuracy and validity of HRA methods and models, leading to significant uncertainty in estimating HEPs. This paper describes research that has the objective to model and quantify team dynamics and teamwork within NPP control room crews for risk informed applications, thereby improving the technical basis of HRA, which improves the risk-informed approach the NRC uses to regulate the U.S. commercial nuclear industry.

External hazards in reliability and risk assessment of nuclear power plants

International Nuclear Information System (INIS)

Stevenson, J.D.

1977-01-01

It is current practice in the design of nuclear power generating stations to protect against the effects of significant natural and man-made external hazards which can occur at the plant site in excess of those hazards normally considered for conventional facilities. This paper is meant to identify those postulated external hazards typically considered in nuclear facility design. The paper also attempts to fulfill the following four objectives: (1) Define the current state of the art in applying reliability and risk analysis to determine external hazard design requirements. (2) Provide a ready source of literature references applicable to probabilistic design for extreme loads. (3) Provide some quantitative probability assessment estimates of external hazards. (4) Develop exclusion criteria by which postulated external hazards can be eliminated as a design basis. Rigorous evaluation of the design requirements for nuclear power plant facilities based on principles of probability and risk analysis is just beginning. It is hoped these techniques will be used more extensively in the future to provide a more rational basis for developing design requirements. (orig.) [de

Safety and reliability assessment

International Nuclear Information System (INIS)

1979-01-01

This report contains the papers delivered at the course on safety and reliability assessment held at the CSIR Conference Centre, Scientia, Pretoria. The following topics were discussed: safety standards; licensing; biological effects of radiation; what is a PWR; safety principles in the design of a nuclear reactor; radio-release analysis; quality assurance; the staffing, organisation and training for a nuclear power plant project; event trees, fault trees and probability; Automatic Protective Systems; sources of failure-rate data; interpretation of failure data; synthesis and reliability; quantification of human error in man-machine systems; dispersion of noxious substances through the atmosphere; criticality aspects of enrichment and recovery plants; and risk and hazard analysis. Extensive examples are given as well as case studies

The Reliability and Predictive Validity of the Stalking Risk Profile.

Science.gov (United States)

McEwan, Troy E; Shea, Daniel E; Daffern, Michael; MacKenzie, Rachel D; Ogloff, James R P; Mullen, Paul E

2018-03-01

This study assessed the reliability and validity of the Stalking Risk Profile (SRP), a structured measure for assessing stalking risks. The SRP was administered at the point of assessment or retrospectively from file review for 241 adult stalkers (91% male) referred to a community-based forensic mental health service. Interrater reliability was high for stalker type, and moderate-to-substantial for risk judgments and domain scores. Evidence for predictive validity and discrimination between stalking recidivists and nonrecidivists for risk judgments depended on follow-up duration. Discrimination was moderate (area under the curve = 0.66-0.68) and positive and negative predictive values good over the full follow-up period ( Mdn = 170.43 weeks). At 6 months, discrimination was better than chance only for judgments related to stalking of new victims (area under the curve = 0.75); however, high-risk stalkers still reoffended against their original victim(s) 2 to 4 times as often as low-risk stalkers. Implications for the clinical utility and refinement of the SRP are discussed.

A reliability-risk modelling of nuclear rad-waste facilities

International Nuclear Information System (INIS)

Lehmann, P.H.; El-Bassioni, A.A.

1975-01-01

Rad-waste disposal systems of nuclear power sites are designed and operated to collect, delay, contain, and concentrate radioactive wastes from reactor plant processes such that on-site and off-site exposures to radiation are well below permissible limits. To assist the designer in achieving minimum release/exposure goals, a computerized reliability-risk model has been developed to simulate the rad-waste system. The objectives of the model are to furnish a practical tool for quantifying the effects of changes in system configuration, operation, and equipment, and for the identification of weak segments in the system design. Primarily, the model comprises a marriage of system analysis, reliability analysis, and release-risk assessment. Provisions have been included in the model to permit the optimization of the system design subject to constraints on cost and rad-releases. The system analysis phase involves the preparation of a physical and functional description of the rad-waste facility accompanied by the formation of a system tree diagram. The reliability analysis phase embodies the formulation of appropriate reliability models and the collection of model parameters. Release-risk assessment constitutes the analytical basis whereupon further system and reliability analyses may be warranted. Release-risk represents the potential for release of radioactivity and is defined as the product of an element's unreliability at time, t, and the radioactivity available for release in time interval, Δt. A computer code (RARISK) has been written to simulate the tree diagram of the rad-waste system. Reliability and release-risk results have been generated for cases which examined the process flow paths of typical rad-waste systems, the effects of repair and standby, the variations of equipment failure and repair rates, and changes in system configurations. The essential feature of this model is that a complex system like the rad-waste facility can be easily decomposed into its

Integration of human reliability analysis into the probabilistic risk assessment process: Phase 1

International Nuclear Information System (INIS)

Bell, B.J.; Vickroy, S.C.

1984-10-01

A research program was initiated to develop a testable set of analytical procedures for integrating human reliability analysis (HRA) into the probabilistic risk assessment (PRA) process to more adequately assess the overall impact of human performance on risk. In this three-phase program, stand-alone HRA/PRA analytic procedures will be developed and field evaluated to provide improved methods, techniques, and models for applying quantitative and qualitative human error data which systematically integrate HRA principles, techniques, and analyses throughout the entire PRA process. Phase 1 of the program involved analysis of state-of-the-art PRAs to define the structures and processes currently in use in the industry. Phase 2 research will involve developing a new or revised PRA methodology which will enable more efficient regulation of the industry using quantitative or qualitative results of the PRA. Finally, Phase 3 will be to field test those procedures to assure that the results generated by the new methodologies will be usable and acceptable to the NRC. This paper briefly describes the first phase of the program and outlines the second

Deterministic quantitative risk assessment development

Energy Technology Data Exchange (ETDEWEB)

Dawson, Jane; Colquhoun, Iain [PII Pipeline Solutions Business of GE Oil and Gas, Cramlington Northumberland (United Kingdom)

2009-07-01

Current risk assessment practice in pipeline integrity management is to use a semi-quantitative index-based or model based methodology. This approach has been found to be very flexible and provide useful results for identifying high risk areas and for prioritizing physical integrity assessments. However, as pipeline operators progressively adopt an operating strategy of continual risk reduction with a view to minimizing total expenditures within safety, environmental, and reliability constraints, the need for quantitative assessments of risk levels is becoming evident. Whereas reliability based quantitative risk assessments can be and are routinely carried out on a site-specific basis, they require significant amounts of quantitative data for the results to be meaningful. This need for detailed and reliable data tends to make these methods unwieldy for system-wide risk k assessment applications. This paper describes methods for estimating risk quantitatively through the calibration of semi-quantitative estimates to failure rates for peer pipeline systems. The methods involve the analysis of the failure rate distribution, and techniques for mapping the rate to the distribution of likelihoods available from currently available semi-quantitative programs. By applying point value probabilities to the failure rates, deterministic quantitative risk assessment (QRA) provides greater rigor and objectivity than can usually be achieved through the implementation of semi-quantitative risk assessment results. The method permits a fully quantitative approach or a mixture of QRA and semi-QRA to suit the operator's data availability and quality, and analysis needs. For example, consequence analysis can be quantitative or can address qualitative ranges for consequence categories. Likewise, failure likelihoods can be output as classical probabilities or as expected failure frequencies as required. (author)

Sequential decision reliability concept and failure rate assessment

International Nuclear Information System (INIS)

Ciftcioglu, O.

1990-11-01

Conventionally, a reliability concept is considered together with both each basic unit and their integration in a complicated large scale system such as a nuclear power plant (NPP). Basically, as the plant's operational status is determined by the information obtained from various sensors, the plant's reliability and the risk assessment is closely related to the reliability of the sensory information and hence the sensor components. However, considering the relevant information-processing systems, e.g. fault detection processors, there exists a further question about the reliability of such systems, specifically the reliability of the systems' decision-based outcomes by means of which the further actions are performed. To this end, a general sequential decision reliability concept and the failure rate assessment methodology is introduced. The implications of the methodology are investigated and the importance of the decision reliability concept in system operation is demonstrated by means of sensory signals in real-time from the Borssele NPP in the Netherlands. (author). 21 refs.; 8 figs

On risk assessment of energy production

International Nuclear Information System (INIS)

Kunii, Katsuhiko

2005-07-01

Today we cannot ignore the risk of health and/or environment by energy production such as power generation since the risk has been made large enough. In this report an information survey has been done in order to know the outline and points of risk assessment. Based on the information of reports and literature about risk assessment, have been surveyed mainly the external cost assessment of power generation (in which quantification of health and/or environment risk has been done), in addition, risks of disasters, accidents, investments, finance etc. and impacts of those risks on social activities. The remarks obtained by the survey are as follows: 1) Some of external cost assessment of power generation show different results even if the assessment conditions of technology, site, etc. are mostly the same. It is necessary to remark on the information such as basic data, model, background, application limit of assessment considering the reliability. 2) Especially it is considered that the reliability of risk assessment is not enough at present because of the lack of basic data. (author)

Risk assessment

International Nuclear Information System (INIS)

Kinchin, G.H.

1983-01-01

After defining risk and introducing the concept of individual and societal risk, the author considers each of these, restricting considerations to risk of death. Some probabilities of death arising from various causes are quoted, and attention drawn to the care necessary in making comparisons between sets of data and to the distinction between voluntary and involuntary categories and between early and delayed deaths. The presentation of information on societal risk is discussed and examples given. The history of quantified risk assessment is outlined, particularly related to the nuclear industry, the process of assessing risk discussed: identification of hazard causes, the development of accident chains and the use of event trees, the evaluation of probability through the collection of data and their use with fault trees, and the assessment of consequences of hazards in terms of fatalities. Reference is made to the human element and common-made failures, and to studies supporting the development of reliability assessment techniques. Acceptance criteria are discussed for individual and societal risk in the nuclear field, and it is shown that proposed criteria lead to risks conservative by comparison with risks from day-to-day accidents and other potentially hazardous industries. (U.K.)

Operator reliability assessment system (OPERAS)

International Nuclear Information System (INIS)

Singh, A.; Spurgin, A.J.; Martin, T.; Welsch, J.; Hallam, J.W.

1991-01-01

OPERAS is a personal-computer (PC) based software to collect and process simulator data on control-room operators responses during requalification training scenarios. The data collection scheme is based upon approach developed earlier during the EPRI Operator Reliability Experiments project. The software allows automated data collection from simulator, thus minimizing simulator staff time and resources to collect, maintain and process data which can be useful in monitoring, assessing and enhancing the progress of crew reliability and effectiveness. The system is designed to provide the data and output information in the form of user-friendly charts, tables and figures for use by plant staff. OPERAS prototype software has been implemented at the Diablo Canyon (PWR) and Millstone (BWR) plants and is currently being used to collect operator response data. Data collected from similator include plant-state variables such as reactor pressure and temperature, malfunction, times at which annunciators are activated, operator actions and observations of crew behavior by training staff. The data and systematic analytical results provided by the OPERAS system can contribute to increase objectivity by the utility probabilistic risk analysis (PRA) and training staff in monitoring and assessing reliability of their crews

[Evaluation of Suicide Risk Levels in Hospitals: Validity and Reliability Tests].

Science.gov (United States)

Macagnino, Sandro; Steinert, Tilman; Uhlmann, Carmen

2018-05-01

Examination of in-hospital suicide risk levels concerning their validity and their reliability. The internal suicide risk levels were evaluated in a cross sectional study of in 163 inpatients. A reliability check was performed via determining interrater-reliability of senior physician, therapist and the responsible nurse. Within the scope of the validity check, we conducted analyses of criterion validity and construct validity. For the total sample an "acceptable" to "good" interrater-reliability (Kendalls W = .77) of suicide risk levels were obtained. Schizophrenic disorders showed the lowest values, for personality disorders we found the highest level of interrater-reliability. When examining the criterion validity, Item-9 of the BDI-II is substantial correlated to our suicide risk levels (ρ m  = .54, p validity check, affective disorders showed the highest correlation (ρ = .77), compatible also with "convergent validity". They differed with schizophrenic disorders which showed the least concordance (ρ = .43). In-hospital suicide risk levels may represent an important contribution to the assessment of suicidal behavior of inpatients experiencing psychiatric treatment due to their overall good validity and reliability. © Georg Thieme Verlag KG Stuttgart · New York.

Integration of human reliability analysis into the probabilistic risk assessment process: phase 1

International Nuclear Information System (INIS)

Bell, B.J.; Vickroy, S.C.

1985-01-01

The US Nuclear Regulatory Commission and Pacific Northwest Laboratory initiated a research program in 1984 to develop a testable set of analytical procedures for integrating human reliability analysis (HRA) into the probabilistic risk assessment (PRA) process to more adequately assess the overall impact of human performance on risk. In this three phase program, stand-alone HRA/PRA analytic procedures will be developed and field evaluated to provide improved methods, techniques, and models for applying quantitative and qualitative human error data which systematically integrate HRA principles, techniques, and analyses throughout the entire PRA process. Phase 1 of the program involved analysis of state-of-the-art PRAs to define the structures and processes currently in use in the industry. Phase 2 research will involve developing a new or revised PRA methodology which will enable more efficient regulation of the industry using quantitative or qualitative results of the PRA. Finally, Phase 3 will be to field test those procedures to assure that the results generated by the new methodologies will be usable and acceptable to the NRC. This paper briefly describes the first phase of the program and outlines the second

Procedures for controlling the risks of reliability, safety, and availability of technical systems

International Nuclear Information System (INIS)

1987-01-01

The reference book covers four sections. Apart from the fundamental aspects of the reliability problem, of risk and safety and the relevant criteria with regard to reliability, the material presented explains reliability in terms of maintenance, logistics and availability, and presents procedures for reliability assessment and determination of factors influencing the reliability, together with suggestions for systems technical integration. The reliability assessment consists of diagnostic and prognostic analyses. The section on factors influencing reliability discusses aspects of organisational structures, programme planning and control, and critical activities. (DG) [de

Reliability and validity of a treatment fidelity assessment for motivational interviewing targeting sexual risk behaviors in people living with HIV/AIDS.

Science.gov (United States)

Seng, Elizabeth K; Lovejoy, Travis I

2013-12-01

This study psychometrically evaluates the Motivational Interviewing Treatment Integrity Code (MITI) to assess fidelity to motivational interviewing to reduce sexual risk behaviors in people living with HIV/AIDS. 74 sessions from a pilot randomized controlled trial of motivational interviewing to reduce sexual risk behaviors in people living with HIV were coded with the MITI. Participants reported sexual behavior at baseline, 3-month, and 6-months. Regarding reliability, excellent inter-rater reliability was achieved for measures of behavior frequency across the 12 sessions coded by both coders; global scales demonstrated poor intraclass correlations, but adequate percent agreement. Regarding validity, principle components analyses indicated that a two-factor model accounted for an adequate amount of variance in the data. These factors were associated with decreases in sexual risk behaviors after treatment. The MITI is a reliable and valid measurement of treatment fidelity for motivational interviewing targeting sexual risk behaviors in people living with HIV/AIDS.

Decision-theoretic methodology for reliability and risk allocation in nuclear power plants

International Nuclear Information System (INIS)

Cho, N.Z.; Papazoglou, I.A.; Bari, R.A.; El-Bassioni, A.

1985-01-01

This paper describes a methodology for allocating reliability and risk to various reactor systems, subsystems, components, operations, and structures in a consistent manner, based on a set of global safety criteria which are not rigid. The problem is formulated as a multiattribute decision analysis paradigm; the multiobjective optimization, which is performed on a PRA model and reliability cost functions, serves as the guiding principle for reliability and risk allocation. The concept of noninferiority is used in the multiobjective optimization problem. Finding the noninferior solution set is the main theme of the current approach. The assessment of the decision maker's preferences could then be performed more easily on the noninferior solution set. Some results of the methodology applications to a nontrivial risk model are provided and several outstanding issues such as generic allocation and preference assessment are discussed

Testing the reliability of the Fall Risk Screening Tool in an elderly ambulatory population.

Science.gov (United States)

Fielding, Susan J; McKay, Michael; Hyrkas, Kristiina

2013-11-01

To identify and test the reliability of a fall risk screening tool in an ambulatory outpatient clinic. The Fall Risk Screening Tool (Albert Lea Medical Center, MN, USA) was scripted for an interview format. Two interviewers separately screened a convenience sample of 111 patients (age ≥ 65 years) in an ambulatory outpatient clinic in a northeastern US city. The interviewers' scoring of fall risk categories was similar. There was good internal consistency (Cronbach's α = 0.834-0.889) and inter-rater reliability [intra-class correlation coefficients (ICC) = 0.824-0.881] for total, Risk Factor and Client's Health Status subscales. The Physical Environment scores indicated acceptable internal consistency (Cronbach's α = 0.742) and adequate reliability (ICC = 0.688). Two Physical Environment items (furniture and medical equipment condition) had low reliabilities [Kappa (K) = 0.323, P = 0.08; K = -0.078, P = 0.648), respectively. The scripted Fall Risk Screening Tool demonstrated good reliability in this sample. Rewording two Physical Environment items will be considered. A reliable instrument such as the scripted Fall Risk Screening Tool provides a standardised assessment for identifying high fall risk patients. This tool is especially useful because it assesses personal, behavioural and environmental factors specific to community-dwelling patients; the interview format also facilitates patient-provider interaction. © 2013 John Wiley & Sons Ltd.

Systamatic approach to integration of a human reliability analysis into a NPP probabalistic risk assessment

International Nuclear Information System (INIS)

Fragola, J.R.

1984-01-01

This chapter describes the human reliability analysis tasks which were employed in the evaluation of the overall probability of an internal flood sequence and its consequences in terms of disabling vulnerable risk significant equipment. Topics considered include the problem familiarization process, the identification and classification of key human interactions, a human interaction review of potential initiators, a maintenance and operations review, human interaction identification, quantification model selection, the definition of operator-induced sequences, the quantification of specific human interactions, skill- and rule-based interactions, knowledge-based interactions, and the incorporation of human interaction-related events into the event tree structure. It is concluded that an integrated approach to the analysis of human interaction within the context of a Probabilistic Risk Assessment (PRA) is feasible

OSS reliability measurement and assessment

CERN Document Server

Yamada, Shigeru

2016-01-01

This book analyses quantitative open source software (OSS) reliability assessment and its applications, focusing on three major topic areas: the Fundamentals of OSS Quality/Reliability Measurement and Assessment; the Practical Applications of OSS Reliability Modelling; and Recent Developments in OSS Reliability Modelling. Offering an ideal reference guide for graduate students and researchers in reliability for open source software (OSS) and modelling, the book introduces several methods of reliability assessment for OSS including component-oriented reliability analysis based on analytic hierarchy process (AHP), analytic network process (ANP), and non-homogeneous Poisson process (NHPP) models, the stochastic differential equation models and hazard rate models. These measurement and management technologies are essential to producing and maintaining quality/reliable systems using OSS.

Assessing the relative and absolute reliability of the Falls Efficacy Scale-International questionnaire in elderly individuals with increased fall risk and the questionnaire's convergent validity in elderly women with osteoporosis.

Science.gov (United States)

Halvarsson, A; Franzén, E; Ståhle, A

2013-06-01

The Falls Efficacy Scale-International (FES-I) is a highly reliable questionnaire for assessing fear of falling in elderly individuals with increased fall risk and has low or no convergent validity with balance performance tests and health-related quality of life (HRQL) among elderly women with osteoporosis, which indicates that both measurements should be included as they are measuring different components. Fear of falling is increased in elderly individuals with osteoporosis and FES-I is a widely used questionnaire to assess fear of falling. There is limited evidence of the reliability and convergent validity in elderly with increased risk of falling and osteoporosis. Reliability and validity study of the FES-I. Community-dwelling elderly with increased fall risk, 59 subjects, were recruited to the reliability assessment, and 81 women with osteoporosis, in the validity assessment. For the reliability assessment, two postal surveys were used. For the validity assessment, we used baseline data from an on-going study in women with osteoporosis. The FES-I was correlated to a single-item question regarding fear of falling, self-reported history of falls, balance performance tests and health-related quality of life. The FES-I had very good relative reliability (intra-class correlation 0.88) and internal consistency reliability (Cronbach's alpha 0.94). The value for absolute reliability was a standard error of measure 2.9 (10.6 %), smallest real difference 7.9 (29 %). There was "little if any" to "low" correlation between the FES-I and the single-item question regarding fear of falling and self-reported history of falls, HRQL and balance performance tests. The FES-I seems to be a highly reliable questionnaire for assessing fear of falling in elderly with increased fall risk but has low relation to/convergent validity with balance performance and HRQL among elderly women with osteoporosis.

Influence of the human reliability in the assessment of the impact on the risk of changes of CLO

International Nuclear Information System (INIS)

Martorell, P.; Martorell, S.; Marton, I.; Saiz, M.

2014-01-01

Treatment and study of epistemic uncertainties is of special importance in the application of the analysis of probabilistic security to informed decision-making in risk, as points out the guide regulatory 1,174 [1] (Regulatory Guide 1,174, RG1.174). Specifically, the RG 1.177 [2] details of the impact on risk assessment concerning changes in the technical operating specifications (ETF). Based on the framework defined by such regulatory guides, will be assessed the effect of uncertainties epistemic associated with the analysis of human reliability in the context of the limit conditions of operation. As an example of application, will be held a sensitivity study of the time of inoperability Completion Time, the Residual heat removal system. (Author)

The reliability of the Hendrich Fall Risk Model in a geriatric hospital.

Science.gov (United States)

Heinze, Cornelia; Halfens, Ruud; Dassen, Theo

2008-12-01

Aims and objectives.  The purpose of this study was to test the interrater reliability of the Hendrich Fall Risk Model, an instrument to identify patients in a hospital setting with a high risk of falling. Background.  Falls are a serious problem in older patients. Valid and reliable fall risk assessment tools are required to identify high-risk patients and to take adequate preventive measures. Methods.  Seventy older patients were independently and simultaneously assessed by six pairs of raters made up of nursing staff members. Consensus estimates were calculated using simple percentage agreement and consistency estimates using Spearman's rho and intra class coefficient. Results.  Percentage agreement ranged from 0.70 to 0.92 between the six pairs of raters. Spearman's rho coefficients were between 0.54 and 0.80 and the intra class coefficients were between 0.46 and 0.92. Conclusions.  Whereas some pairs of raters obtained considerable interobserver agreement and internal consistency, the others did not. Therefore, it is concluded that the Hendrich Fall Risk Model is not a reliable instrument. The use of more unambiguous operationalized items is preferred. Relevance to clinical practice.  In practice, well operationalized fall risk assessment tools are necessary. Observer agreement should always be investigated after introducing a standardized measurement tool. © 2008 The Authors. Journal compilation © 2008 Blackwell Publishing Ltd.

Interrater reliability of Violence Risk Appraisal Guide scores provided in Canadian criminal proceedings.

Science.gov (United States)

Edens, John F; Penson, Brittany N; Ruchensky, Jared R; Cox, Jennifer; Smith, Shannon Toney

2016-12-01

Published research suggests that most violence risk assessment tools have relatively high levels of interrater reliability, but recent evidence of inconsistent scores among forensic examiners in adversarial settings raises concerns about the "field reliability" of such measures. This study specifically examined the reliability of Violence Risk Appraisal Guide (VRAG) scores in Canadian criminal cases identified in the legal database, LexisNexis. Over 250 reported cases were located that made mention of the VRAG, with 42 of these cases containing 2 or more scores that could be submitted to interrater reliability analyses. Overall, scores were skewed toward higher risk categories. The intraclass correlation (ICCA1) was .66, with pairs of forensic examiners placing defendants into the same VRAG risk "bin" in 68% of the cases. For categorical risk statements (i.e., low, moderate, high), examiners provided converging assessment results in most instances (86%). In terms of potential predictors of rater disagreement, there was no evidence for adversarial allegiance in our sample. Rater disagreement in the scoring of 1 VRAG item (Psychopathy Checklist-Revised; Hare, 2003), however, strongly predicted rater disagreement in the scoring of the VRAG (r = .58). (PsycINFO Database Record (c) 2016 APA, all rights reserved).

Probabilistic risk assessment for a loss of coolant accident in McMaster Nuclear Reactor and application of reliability physics model for modeling human reliability

Science.gov (United States)

Ha, Taesung

A probabilistic risk assessment (PRA) was conducted for a loss of coolant accident, (LOCA) in the McMaster Nuclear Reactor (MNR). A level 1 PRA was completed including event sequence modeling, system modeling, and quantification. To support the quantification of the accident sequence identified, data analysis using the Bayesian method and human reliability analysis (HRA) using the accident sequence evaluation procedure (ASEP) approach were performed. Since human performance in research reactors is significantly different from that in power reactors, a time-oriented HRA model (reliability physics model) was applied for the human error probability (HEP) estimation of the core relocation. This model is based on two competing random variables: phenomenological time and performance time. The response surface and direct Monte Carlo simulation with Latin Hypercube sampling were applied for estimating the phenomenological time, whereas the performance time was obtained from interviews with operators. An appropriate probability distribution for the phenomenological time was assigned by statistical goodness-of-fit tests. The human error probability (HEP) for the core relocation was estimated from these two competing quantities: phenomenological time and operators' performance time. The sensitivity of each probability distribution in human reliability estimation was investigated. In order to quantify the uncertainty in the predicted HEPs, a Bayesian approach was selected due to its capability of incorporating uncertainties in model itself and the parameters in that model. The HEP from the current time-oriented model was compared with that from the ASEP approach. Both results were used to evaluate the sensitivity of alternative huinan reliability modeling for the manual core relocation in the LOCA risk model. This exercise demonstrated the applicability of a reliability physics model supplemented with a. Bayesian approach for modeling human reliability and its potential

Human reliability in probabilistic safety assessments

International Nuclear Information System (INIS)

Nunez Mendez, J.

1989-01-01

Nowadays a growing interest in medioambiental aspects is detected in our country. It implies an assessment of the risk involved in the industrial processess and installations in order to determine if those are into the acceptable limits. In these safety assessments, among which PSA (Probabilistic Safety Assessments), can be pointed out the role played by the human being in the system is one of the more relevant subjects. (This relevance has been demostrated in the accidents happenned). However in Spain there aren't manuals specifically dedicated to asses the human contribution to risk in the frame of PSAs. This report aims to improve this situation providing: a) a theoretical background to help the reader in the understanding of the nature of the human error, b) a guide to carry out a Human Reliability Analysis and c) a selected overwiev of the techniques and methodologies currently applied in this area. (Author)

Application of structural reliability and risk assessment to life prediction and life extension decision making

International Nuclear Information System (INIS)

Meyer, T.A.; Balkey, K.R.; Bishop, B.A.

1987-01-01

There can be numerous uncertainties involved in performing component life assessments. In addition, sufficient data may be unavailable to make a useful life prediction. Structural Reliability and Risk Assessment (SRRA) is primarily an analytical methodology or tool that quantifies the impact of uncertainties on the structural life of plant components and can address the lack of data in component life prediction. As a prelude to discussing the technical aspects of SRRA, a brief review of general component life prediction methods is first made so as to better develop an understanding of the role of SRRA in such evaluations. SRRA is then presented as it is applied in component life evaluations with example applications being discussed for both nuclear and non-nuclear components

Risk and reliability allocation to risk control

International Nuclear Information System (INIS)

Vojnovic, D.; Kozuh, M.

1992-01-01

The risk allocation procedure is used as an analytical model to support the optimal decision making for reliability/availability improvement planning. Both levels of decision criteria, the plant risk measures and plant performance indices, are used in risk allocation procedure. Decision support system uses the multi objective decision making concept. (author) [sl

Human Reliability in Probabilistic Safety Assessments

International Nuclear Information System (INIS)

Nunez Mendez, J.

1989-01-01

Nowadays a growing interest in environmental aspects is detected in our country. It implies an assessment of the risk involved in the industrial processes and installations in order to determine if those are into the acceptable limits. In these safety assessments, among which PSA (Probabilistic Safety Assessments), can be pointed out the role played by the human being in the system is one of the more relevant subjects (This relevance has been demonstrated in the accidents happened) . However, in Spain there aren't manuals specifically dedicated to asses the human contribution to risk in the frame of PSAs. This report aims to improve this situation providing: a) a theoretical background to help the reader in the understanding of the nature of the human error, b) a quid to carry out a Human Reliability Analysis and c) a selected overview of the techniques and methodologies currently applied in this area. (Author) 20 refs

Reliability of blood pressure measurement and cardiovascular risk prediction

NARCIS (Netherlands)

van der Hoeven, N.V.

2016-01-01

High blood pressure is one of the leading risk factors for cardiovascular disease, but difficult to reliably assess because there are many factors which can influence blood pressure including stress, exercise or illness. The first part of this thesis focuses on possible ways to improve the

Predicting risk and human reliability: a new approach

International Nuclear Information System (INIS)

Duffey, R.; Ha, T.-S.

2009-01-01

Learning from experience describes human reliability and skill acquisition, and the resulting theory has been validated by comparison against millions of outcome data from multiple industries and technologies worldwide. The resulting predictions were used to benchmark the classic first generation human reliability methods adopted in probabilistic risk assessments. The learning rate, probabilities and response times are also consistent with the existing psychological models for human learning and error correction. The new approach also implies a finite lower bound probability that is not predicted by empirical statistical distributions that ignore the known and fundamental learning effects. (author)

Developments in Levee Reliability and Flood Risk Analysis in the Netherlands

NARCIS (Netherlands)

Jonkman, S.N.; Schweckendiek, T.

2015-01-01

This paper presents and overview of advances in flood risk and levee reliability analysis in the Netherlands. It is described how new safety standards – in the form of a target failure probability – have been derived on the basis of nationwide flood risk assessments which taken into account both

Risk and reliability analysis theory and applications : in honor of Prof. Armen Der Kiureghian

CERN Document Server

2017-01-01

This book presents a unique collection of contributions from some of the foremost scholars in the field of risk and reliability analysis. Combining the most advanced analysis techniques with practical applications, it is one of the most comprehensive and up-to-date books available on risk-based engineering. All the fundamental concepts needed to conduct risk and reliability assessments are covered in detail, providing readers with a sound understanding of the field and making the book a powerful tool for students and researchers alike. This book was prepared in honor of Professor Armen Der Kiureghian, one of the fathers of modern risk and reliability analysis.

The Validity and Reliability of the Turkish Version of the Neonatal Skin Risk Assessment Scale.

Science.gov (United States)

Sari, Çiğdem; Altay, Naime

2017-03-01

The study created a Turkish translation of the Neonatal Skin Risk Assessment Scale (NSRAS) that was developed by Huffines and Longsdon in 1997. Study authors used a cross-sectional survey design in order to determine the validity and reliability of the Turkish translation. The study was conducted at the neonatal intensive care unit of a university hospital in Ankara between March 15 and June 30, 2014. The research sample included 130 neonatal assessments from 17 patients. Data were collected by questionnaire regarding the characteristics of the participating neonates, 7 nurse observers, and the NSRAS and its subarticles. After translation and back-translation were performed to assess language validity of the scale, necessary corrections were made in line with expert suggestions, and content validity was ensured. Internal consistency of the scale was assessed by its homogeneity, Cronbach's α, and subarticle-general scale grade correlation. Cronbach's α for the scale overall was .88, and Cronbach's α values for the subarticles were between .83 and .90. Results showed a positive relationship among all the subarticles and the overall NSRAS scale grade (P Kaiser-Meyer-Olkin analysis was applied for sample sufficiency, and Bartlett test analysis was applied in order to assess the factor analysis of the sample. The Kaiser-Meyer-Olkin coefficient was 0.73, and the χ value found according to the Bartlett test was statistically significant at an advanced level (P < .05). In the 6 subarticles of the scale and in the general scale total grade, a high, positive, and significant relationship among the grades given by the researcher and the nurse observers was found (P < .05). The Turkish NSRAS is reliable and valid.

Screening for Psychosocial Risk in Dutch Families of a Child With Cancer: Reliability, Validity, and Usability of the Psychosocial Assessment Tool

NARCIS (Netherlands)

Sint Nicolaas, Simone M.; Schepers, Sasja A.; Hoogerbrugge, Peter M.; Caron, Huib N.; Kaspers, Gertjan J. L.; van den Heuvel-Eibrink, Marry M.; Grootenhuis, Martha A.; Verhaak, Chris M.

2016-01-01

The Psychosocial Assessment Tool (PAT) was developed to screen for psychosocial risk in families of a child diagnosed with cancer. The current study is the first describing the cross-cultural adaptation, reliability, validity, and usability of the PAT in an European country (Dutch translation).   A

Commentary: Risk Management and Reliability Design for Buildings

Energy Technology Data Exchange (ETDEWEB)

Berry, Dennis L.; Cranwell, Robert M.; Hunter, Regina L.

1999-05-28

Where there is a significant actuarial basis for decision making (e.g., the occurrence of fires in single-family dwellings), there is little incentive for formal risk management. Formal risk assessments are most useful in those cases where the value of the structure is high, many people may be affected, the societal perception of risk is high, consequences of a mishap would be severe, and the actuarial uncertainty is large. For these cases, there is little opportunity to obtain the necessary experiential data to make informed decisions, and the consequences in terms of money, lives, and societal confidence are severe enough to warrant a formal risk assessment. Other important factors include the symbolic value of the structure and vulnerability to single point failures. It is unlikely that formal risk management and assessment practices will or should replace the proven institutions of building codes and engineering practices. Nevertheless, formal risk assessment can provide valuable insights into the hazards threatening high-value and high-risk (perceived or actual) buildings and structures, which can in turn be translated into improved public health, safety, and security. The key is to choose and apply the right assessment tool to match the structure in question. Design-for-reliability concepts can be applied to buildings, bridges, transportation sys- tems, dams, and other structures. The use of these concepts could have the dual benefits of lowering life-cycle costs by reducing the necessity for maintenance and repair and of enhancing the saiiety and security of the structure's users.

Reliability and validity of risk analysis

International Nuclear Information System (INIS)

Aven, Terje; Heide, Bjornar

2009-01-01

In this paper we investigate to what extent risk analysis meets the scientific quality requirements of reliability and validity. We distinguish between two types of approaches within risk analysis, relative frequency-based approaches and Bayesian approaches. The former category includes both traditional statistical inference methods and the so-called probability of frequency approach. Depending on the risk analysis approach, the aim of the analysis is different, the results are presented in different ways and consequently the meaning of the concepts reliability and validity are not the same.

Reliability of risk-adjusted outcomes for profiling hospital surgical quality.

Science.gov (United States)

Krell, Robert W; Hozain, Ahmed; Kao, Lillian S; Dimick, Justin B

2014-05-01

Quality improvement platforms commonly use risk-adjusted morbidity and mortality to profile hospital performance. However, given small hospital caseloads and low event rates for some procedures, it is unclear whether these outcomes reliably reflect hospital performance. To determine the reliability of risk-adjusted morbidity and mortality for hospital performance profiling using clinical registry data. A retrospective cohort study was conducted using data from the American College of Surgeons National Surgical Quality Improvement Program, 2009. Participants included all patients (N = 55,466) who underwent colon resection, pancreatic resection, laparoscopic gastric bypass, ventral hernia repair, abdominal aortic aneurysm repair, and lower extremity bypass. Outcomes included risk-adjusted overall morbidity, severe morbidity, and mortality. We assessed reliability (0-1 scale: 0, completely unreliable; and 1, perfectly reliable) for all 3 outcomes. We also quantified the number of hospitals meeting minimum acceptable reliability thresholds (>0.70, good reliability; and >0.50, fair reliability) for each outcome. For overall morbidity, the most common outcome studied, the mean reliability depended on sample size (ie, how high the hospital caseload was) and the event rate (ie, how frequently the outcome occurred). For example, mean reliability for overall morbidity was low for abdominal aortic aneurysm repair (reliability, 0.29; sample size, 25 cases per year; and event rate, 18.3%). In contrast, mean reliability for overall morbidity was higher for colon resection (reliability, 0.61; sample size, 114 cases per year; and event rate, 26.8%). Colon resection (37.7% of hospitals), pancreatic resection (7.1% of hospitals), and laparoscopic gastric bypass (11.5% of hospitals) were the only procedures for which any hospitals met a reliability threshold of 0.70 for overall morbidity. Because severe morbidity and mortality are less frequent outcomes, their mean

Risk and reliability analyses (LURI) and expert judgement techniques

International Nuclear Information System (INIS)

Pyy, P.; Pulkkinen, U.

1998-01-01

Probabilistic safety analysis (PSA) is currently used as a regulatory licensing tool in risk informed and plant performance based regulation. More often also utility safety improvements are based on PSA calculations as one criterion. PSA attempts to comprehensively identify all important risk contributors, compare them with each other, assess the safety level and suggest improvements based on its findings. The strength of PSA is that it is capable to provide decision makers with numerical estimates of risks. This makes decision making easier than the comparison of purely qualitative results. PSA is the only comprehensive tool that compactly attempts to include all the important risk contributors in its scope. Despite the demonstrated strengths of PSA, there are some features that have reduced its uses. For example, the PSA scope has been limited to the power operation and process internal events (transients and LOCAs). Only lately, areas such as shutdown, external events and severe accidents have been included in PSA models in many countries. Problems related to modelling are, e.g., that rather static fault and event tree models are commonly used in PSA to model dynamic event sequences. Even if a valid model may be generated, there may not be any other data sources to be used than expert judgement. Furthermore, there are a variety of different techniques for human reliability assessment (HRA) giving varying results. In the project Reliability and Risk Analyses (LURI) these limitations and shortcomings have been studied. In the decision making area, case studies on the application of decision analysis and a doctoral thesis have been published. Further, practical aid has been given to utilities and regulatory decision making. Model uncertainty effect on PSA results has been demonstrated by two case studies. Human reliability has been studied both in the integrated safety analysis study and in the study of maintenance originated NPP component faults based on the

Reliability assessments in qualitative health promotion research.

Science.gov (United States)

Cook, Kay E

2012-03-01

This article contributes to the debate about the use of reliability assessments in qualitative research in general, and health promotion research in particular. In this article, I examine the use of reliability assessments in qualitative health promotion research in response to health promotion researchers' commonly held misconception that reliability assessments improve the rigor of qualitative research. All qualitative articles published in the journal Health Promotion International from 2003 to 2009 employing reliability assessments were examined. In total, 31.3% (20/64) articles employed some form of reliability assessment. The use of reliability assessments increased over the study period, ranging from qualitative articles decreased. The articles were then classified into four types of reliability assessments, including the verification of thematic codes, the use of inter-rater reliability statistics, congruence in team coding and congruence in coding across sites. The merits of each type were discussed, with the subsequent discussion focusing on the deductive nature of reliable thematic coding, the limited depth of immediately verifiable data and the usefulness of such studies to health promotion and the advancement of the qualitative paradigm.

Approach to reliability assessment

International Nuclear Information System (INIS)

Green, A.E.; Bourne, A.J.

1975-01-01

Experience has shown that reliability assessments can play an important role in the early design and subsequent operation of technological systems where reliability is at a premium. The approaches to and techniques for such assessments, which have been outlined in the paper, have been successfully applied in variety of applications ranging from individual equipments to large and complex systems. The general approach involves the logical and systematic establishment of the purpose, performance requirements and reliability criteria of systems. This is followed by an appraisal of likely system achievment based on the understanding of different types of variational behavior. A fundamental reliability model emerges from the correlation between the appropriate Q and H functions for performance requirement and achievement. This model may cover the complete spectrum of performance behavior in all the system dimensions

Building better environmental risk assessments

Directory of Open Access Journals (Sweden)

Raymond eLayton

2015-08-01

Full Text Available Risk assessment is a reasoned, structured approach to address uncertainty based on scientific and technical evidence. It forms the foundation for regulatory decision making, which is bound by legislative and policy requirements, as well as the need for making timely decisions using available resources. In order to be most useful, environmental risk assessments (ERA for genetically modified (GM crops should provide consistent, reliable, and transparent results across all types of GM crops, traits, and environments. The assessments must also separate essential information from scientific or agronomic data of marginal relevance or value for evaluating risk and complete the assessment in a timely fashion. Challenges in conducting ERAs differ across regulatory systems – examples are presented from Canada, Malaysia, and Argentina. One challenge faced across the globe is the conduct of risk assessments with limited resources. This challenge can be overcome by clarifying risk concepts, placing greater emphasis on data critical to assess environmental risk (for example, phenotypic and plant performance data rather than molecular data, and adapting advances in risk analysis from other relevant disciplines.

Building Better Environmental Risk Assessments

Science.gov (United States)

Layton, Raymond; Smith, Joe; Macdonald, Phil; Letchumanan, Ramatha; Keese, Paul; Lema, Martin

2015-01-01

Risk assessment is a reasoned, structured approach to address uncertainty based on scientific and technical evidence. It forms the foundation for regulatory decision-making, which is bound by legislative and policy requirements, as well as the need for making timely decisions using available resources. In order to be most useful, environmental risk assessments (ERAs) for genetically modified (GM) crops should provide consistent, reliable, and transparent results across all types of GM crops, traits, and environments. The assessments must also separate essential information from scientific or agronomic data of marginal relevance or value for evaluating risk and complete the assessment in a timely fashion. Challenges in conducting ERAs differ across regulatory systems – examples are presented from Canada, Malaysia, and Argentina. One challenge faced across the globe is the conduct of risk assessments with limited resources. This challenge can be overcome by clarifying risk concepts, placing greater emphasis on data critical to assess environmental risk (for example, phenotypic and plant performance data rather than molecular data), and adapting advances in risk analysis from other relevant disciplines. PMID:26301217

Building Better Environmental Risk Assessments.

Science.gov (United States)

Layton, Raymond; Smith, Joe; Macdonald, Phil; Letchumanan, Ramatha; Keese, Paul; Lema, Martin

2015-01-01

Risk assessment is a reasoned, structured approach to address uncertainty based on scientific and technical evidence. It forms the foundation for regulatory decision-making, which is bound by legislative and policy requirements, as well as the need for making timely decisions using available resources. In order to be most useful, environmental risk assessments (ERAs) for genetically modified (GM) crops should provide consistent, reliable, and transparent results across all types of GM crops, traits, and environments. The assessments must also separate essential information from scientific or agronomic data of marginal relevance or value for evaluating risk and complete the assessment in a timely fashion. Challenges in conducting ERAs differ across regulatory systems - examples are presented from Canada, Malaysia, and Argentina. One challenge faced across the globe is the conduct of risk assessments with limited resources. This challenge can be overcome by clarifying risk concepts, placing greater emphasis on data critical to assess environmental risk (for example, phenotypic and plant performance data rather than molecular data), and adapting advances in risk analysis from other relevant disciplines.

Reliability assessment of competing risks with generalized mixed shock models

International Nuclear Information System (INIS)

Rafiee, Koosha; Feng, Qianmei; Coit, David W.

2017-01-01

This paper investigates reliability modeling for systems subject to dependent competing risks considering the impact from a new generalized mixed shock model. Two dependent competing risks are soft failure due to a degradation process, and hard failure due to random shocks. The shock process contains fatal shocks that can cause hard failure instantaneously, and nonfatal shocks that impact the system in three different ways: 1) damaging the unit by immediately increasing the degradation level, 2) speeding up the deterioration by accelerating the degradation rate, and 3) weakening the unit strength by reducing the hard failure threshold. While the first impact from nonfatal shocks comes from each individual shock, the other two impacts are realized when the condition for a new generalized mixed shock model is satisfied. Unlike most existing mixed shock models that consider a combination of two shock patterns, our new generalized mixed shock model includes three classic shock patterns. According to the proposed generalized mixed shock model, the degradation rate and the hard failure threshold can simultaneously shift multiple times, whenever the condition for one of these three shock patterns is satisfied. An example using micro-electro-mechanical systems devices illustrates the effectiveness of the proposed approach with sensitivity analysis. - Highlights: • A rich reliability model for systems subject to dependent failures is proposed. • The degradation rate and the hard failure threshold can shift simultaneously. • The shift is triggered by a new generalized mixed shock model. • The shift can occur multiple times under the generalized mixed shock model.

Preventive risk assessment in forensic child and youth care

NARCIS (Netherlands)

Assink, M.

2017-01-01

Risk assessment is central to the work of forensic mental health professionals, since it serves as a guide for prevention and intervention strategies. For effective risk assessment, knowledge on risk factors and their effects as well as the availability of valid and reliable instruments for risk

A prospective study assessing agreement and reliability of a geriatric evaluation.

Science.gov (United States)

Locatelli, Isabella; Monod, Stéfanie; Cornuz, Jacques; Büla, Christophe J; Senn, Nicolas

2017-07-19

The present study takes place within a geriatric program, aiming at improving the diagnosis and management of geriatric syndromes in primary care. Within this program it was of prime importance to be able to rely on a robust and reproducible geriatric consultation to use as a gold standard for evaluating a primary care brief assessment tool. The specific objective of the present study was thus assessing the agreement and reliability of a comprehensive geriatric consultation. The study was conducted at the outpatient clinic of the Service of Geriatric Medicine, University of Lausanne, Switzerland. All community-dwelling older persons aged 70 years and above were eligible. Patients were excluded if they hadn't a primary care physician, they were unable to speak French, or they were already assessed by a geriatrician within the last 12 months. A set of 9 geriatricians evaluated 20 patients. Each patient was assessed twice within a 2-month delay. Geriatric consultations were based on a structured evaluation process, leading to rating the following geriatric conditions: functional, cognitive, visual, and hearing impairment, mood disorders, risk of fall, osteoporosis, malnutrition, and urinary incontinence. Reliability and agreement estimates on each of these items were obtained using a three-way Intraclass Correlation and a three-way Observed Disagreement index. The latter allowed a decomposition of overall disagreement into disagreements due to each source of error variability (visit, rater and random). Agreement ranged between 0.62 and 0.85. For most domains, geriatrician-related error variability explained an important proportion of disagreement. Reliability ranged between 0 and 0.8. It was poor/moderate for visual impairment, malnutrition and risk of fall, and good/excellent for functional/cognitive/hearing impairment, osteoporosis, incontinence and mood disorders. Six out of nine items of the geriatric consultation described in this study (functional

Reliability Assessment Of Wind Turbines

DEFF Research Database (Denmark)

Sørensen, John Dalsgaard

2014-01-01

Reduction of cost of energy for wind turbines are very important in order to make wind energy competitive compared to other energy sources. Therefore the turbine components should be designed to have sufficient reliability but also not be too costly (and safe). This paper presents models...... for uncertainty modeling and reliability assessment of especially the structural components such as tower, blades, substructure and foundation. But since the function of a wind turbine is highly dependent on many electrical and mechanical components as well as a control system also reliability aspects...... of these components are discussed and it is described how there reliability influences the reliability of the structural components. Two illustrative examples are presented considering uncertainty modeling, reliability assessment and calibration of partial safety factors for structural wind turbine components exposed...

[Reliability and validity of the Braden Scale for predicting pressure sore risk].

Science.gov (United States)

Boes, C

2000-12-01

For more accurate and objective pressure sore risk assessment various risk assessment tools were developed mainly in the USA and Great Britain. The Braden Scale for Predicting Pressure Sore Risk is one such example. By means of a literature analysis of German and English texts referring to the Braden Scale the scientific control criteria reliability and validity will be traced and consequences for application of the scale in Germany will be demonstrated. Analysis of 4 reliability studies shows an exclusive focus on interrater reliability. Further, even though examination of 19 validity studies occurs in many different settings, such examination is limited to the criteria sensitivity and specificity (accuracy). The range of sensitivity and specificity level is 35-100%. The recommended cut off points rank in the field of 10 to 19 points. The studies prove to be not comparable with each other. Furthermore, distortions in these studies can be found which affect accuracy of the scale. The results of the here presented analysis show an insufficient proof for reliability and validity in the American studies. In Germany, the Braden scale has not yet been tested under scientific criteria. Such testing is needed before using the scale in different German settings. During the course of such testing, construction and study procedures of the American studies can be used as a basis as can the problems be identified in the analysis presented below.

Evaluation of piping reliability and failure data for use in risk-based inspections of nuclear power plants

International Nuclear Information System (INIS)

Vasconcelos, V. de; Soares, W.A.; Costa, A.C.L. da; Rabello, E.G.; Marques, R.O.

2016-01-01

During operation of industrial facilities, components and systems can deteriorate over time, thus increasing the possibility of accidents. Risk-Based Inspection (RBI) involves inspection planning based on information about risks, through assessing of probability and consequence of failures. In-service inspections are used in nuclear power plants, in order to ensure reliable and safe operation. Traditional deterministic inspection approaches investigate generic degradation mechanisms on all systems. However, operating experience indicates that degradation occurs where there are favorable conditions for developing a specific mechanism. Inspections should be prioritized at these places. Risk-Informed In-service Inspections (RI-ISI) are types of RBI that use Probabilistic Safety Assessment results, increasing reliability and plant safety, and reducing radiation exposure. These assessments use both available generic reliability and failure data, as well as plant specific information. This paper proposes a method for evaluating piping reliability and failure data important for RI-ISI programs, as well as the techniques involved. (author)

Evaluation of piping reliability and failure data for use in risk-based inspections of nuclear power plants

Energy Technology Data Exchange (ETDEWEB)

Vasconcelos, V. de; Soares, W.A.; Costa, A.C.L. da; Rabello, E.G.; Marques, R.O., E-mail: vasconv@cdtn.br [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil)

2016-07-01

During operation of industrial facilities, components and systems can deteriorate over time, thus increasing the possibility of accidents. Risk-Based Inspection (RBI) involves inspection planning based on information about risks, through assessing of probability and consequence of failures. In-service inspections are used in nuclear power plants, in order to ensure reliable and safe operation. Traditional deterministic inspection approaches investigate generic degradation mechanisms on all systems. However, operating experience indicates that degradation occurs where there are favorable conditions for developing a specific mechanism. Inspections should be prioritized at these places. Risk-Informed In-service Inspections (RI-ISI) are types of RBI that use Probabilistic Safety Assessment results, increasing reliability and plant safety, and reducing radiation exposure. These assessments use both available generic reliability and failure data, as well as plant specific information. This paper proposes a method for evaluating piping reliability and failure data important for RI-ISI programs, as well as the techniques involved. (author)

Quantitative evaluation of the impact of human reliability in risk assessment for nuclear power plants

International Nuclear Information System (INIS)

Samanta, P.K.

1981-01-01

The role of human beings in the safe operation of a nuclear power plant has been a matter of concern. This study describes methods for the quantitative description of that role and its impact on the risk from nuclear power plants. The impact of human errors was calculated by observing the changes in risk parameters, such as core melt probability, release category probabilities, accident sequence probabilities and system unavailabilities due to changes in the contribution to unavailablity of human errors, within the framework of risk assessment methodology. It was found that for operational pressurized water reactors the opportunity for reduction in core melt probability by reducing the human error rates without simultaneous reduction of hardware failures is limited, but that core melt probability would significantly increase as human error rates increased. More importantly, most of the dominant accident sequences showed a significant increase in their probabilities with an increase in human error rates. Release categories resulting in high consequences showed a much larger sensitivity to human errors than categories resulting in low consequences. A combination of structural importance and reliability importance measure was used to describe the importance of individual errors

Interactive reliability assessment using an integrated reliability data bank

International Nuclear Information System (INIS)

Allan, R.N.; Whitehead, A.M.

1986-01-01

The logical structure, techniques and practical application of a computer-aided technique based on a microcomputer using floppy disc Random Access Files is described. This interactive computational technique is efficient if the reliability prediction program is coupled directly to a relevant source of data to create an integrated reliability assessment/reliability data bank system. (DG)

The possibilities of applying a risk-oriented approach to the NPP reliability and safety enhancement problem

Science.gov (United States)

Komarov, Yu. A.

2014-10-01

An analysis and some generalizations of approaches to risk assessments are presented. Interconnection between different interpretations of the "risk" notion is shown, and the possibility of applying the fuzzy set theory to risk assessments is demonstrated. A generalized formulation of the risk assessment notion is proposed in applying risk-oriented approaches to the problem of enhancing reliability and safety in nuclear power engineering. The solution of problems using the developed risk-oriented approaches aimed at achieving more reliable and safe operation of NPPs is described. The results of studies aimed at determining the need (advisability) to modernize/replace NPP elements and systems are presented together with the results obtained from elaborating the methodical principles of introducing the repair concept based on the equipment technical state. The possibility of reducing the scope of tests and altering the NPP systems maintenance strategy is substantiated using the risk-oriented approach. A probabilistic model for estimating the validity of boric acid concentration measurements is developed.

Experiences in Germany with reliability data assessment, results and current problems

International Nuclear Information System (INIS)

Homke, P.; Kutsch, W.; Lindauer, E.

1982-01-01

This paper gives a survey on reliability data assessment in the FRG. The activities, which were carried out for the German Risk Assessment Study are presented together with selected results. A systematic data collection in a nuclear power plant is described and the experiences are discussed, which were gained in this project

Risk assessment for construction projects of transport infrastructure objects

Science.gov (United States)

Titarenko, Boris

2017-10-01

The paper analyzes and compares different methods of risk assessment for construction projects of transport objects. The management of such type of projects demands application of special probabilistic methods due to large level of uncertainty of their implementation. Risk management in the projects requires the use of probabilistic and statistical methods. The aim of the work is to develop a methodology for using traditional methods in combination with robust methods that allow obtaining reliable risk assessments in projects. The robust approach is based on the principle of maximum likelihood and in assessing the risk allows the researcher to obtain reliable results in situations of great uncertainty. The application of robust procedures allows to carry out a quantitative assessment of the main risk indicators of projects when solving the tasks of managing innovation-investment projects. Calculation of damage from the onset of a risky event is possible by any competent specialist. And an assessment of the probability of occurrence of a risky event requires the involvement of special probabilistic methods based on the proposed robust approaches. Practice shows the effectiveness and reliability of results. The methodology developed in the article can be used to create information technologies and their application in automated control systems for complex projects.

Systems Analysis Programs for Hands-on Integrated Reliability Evaluations (SAPHIRE), Version 5.0. Volume 5, Systems Analysis and Risk Assessment (SARA) tutorial manual

International Nuclear Information System (INIS)

Sattison, M.B.; Russell, K.D.; Skinner, N.L.

1994-07-01

The Systems Analysis Programs for Hands-on Integrated Reliability Evaluations (SAPHIRE) refers to a set of several microcomputer programs that were developed to create and analyze probabilistic risk assessments (PRAs) primarily for nuclear power plants. This volume is the tutorial manual for the Systems Analysis and Risk Assessment (SARA) System Version 5.0, a microcomputer-based system used to analyze the safety issues of a open-quotes familyclose quotes [i.e., a power plant, a manufacturing facility, any facility on which a probabilistic risk assessment (PRA) might be performed]. A series of lessons is provided that guides the user through some basic steps common to most analyses performed with SARA. The example problems presented in the lessons build on one another, and in combination, lead the user through all aspects of SARA sensitivity analysis capabilities

Dynamical systems probabilistic risk assessment

Energy Technology Data Exchange (ETDEWEB)

Denman, Matthew R. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Ames, Arlo Leroy [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

2014-03-01

Probabilistic Risk Assessment (PRA) is the primary tool used to risk-inform nuclear power regulatory and licensing activities. Risk-informed regulations are intended to reduce inherent conservatism in regulatory metrics (e.g., allowable operating conditions and technical specifications) which are built into the regulatory framework by quantifying both the total risk profile as well as the change in the risk profile caused by an event or action (e.g., in-service inspection procedures or power uprates). Dynamical Systems (DS) analysis has been used to understand unintended time-dependent feedbacks in both industrial and organizational settings. In dynamical systems analysis, feedback loops can be characterized and studied as a function of time to describe the changes to the reliability of plant Structures, Systems and Components (SSCs). While DS has been used in many subject areas, some even within the PRA community, it has not been applied toward creating long-time horizon, dynamic PRAs (with time scales ranging between days and decades depending upon the analysis). Understanding slowly developing dynamic effects, such as wear-out, on SSC reliabilities may be instrumental in ensuring a safely and reliably operating nuclear fleet. Improving the estimation of a plant's continuously changing risk profile will allow for more meaningful risk insights, greater stakeholder confidence in risk insights, and increased operational flexibility.

Assessing the reliability of dose coefficients for exposure to radioiodine by members of the public, accounting for dosimetric and risk model uncertainties.

Science.gov (United States)

Puncher, M; Zhang, W; Harrison, J D; Wakeford, R

2017-06-26

Assessments of risk to a specific population group resulting from internal exposure to a particular radionuclide can be used to assess the reliability of the appropriate International Commission on Radiological Protection (ICRP) dose coefficients used as a radiation protection device for the specified exposure pathway. An estimate of the uncertainty on the associated risk is important for informing judgments on reliability; a derived uncertainty factor, UF, is an estimate of the 95% probable geometric difference between the best risk estimate and the nominal risk and is a useful tool for making this assessment. This paper describes the application of parameter uncertainty analysis to quantify uncertainties resulting from internal exposures to radioiodine by members of the public, specifically 1, 10 and 20-year old females from the population of England and Wales. Best estimates of thyroid cancer incidence risk (lifetime attributable risk) are calculated for ingestion or inhalation of 129 I and 131 I, accounting for uncertainties in biokinetic model and cancer risk model parameter values. These estimates are compared with the equivalent ICRP derived nominal age-, sex- and population-averaged estimates of excess thyroid cancer incidence to obtain UFs. Derived UF values for ingestion or inhalation of 131 I for 1 year, 10-year and 20-year olds are around 28, 12 and 6, respectively, when compared with ICRP Publication 103 nominal values, and 9, 7 and 14, respectively, when compared with ICRP Publication 60 values. Broadly similar results were obtained for 129 I. The uncertainties on risk estimates are largely determined by uncertainties on risk model parameters rather than uncertainties on biokinetic model parameters. An examination of the sensitivity of the results to the risk models and populations used in the calculations show variations in the central estimates of risk of a factor of around 2-3. It is assumed that the direct proportionality of excess thyroid cancer

Competing risk theory and radiation risk assessment

International Nuclear Information System (INIS)

Groer, P.G.

1980-01-01

New statistical procedures are applied to estimate cumulative distribution functions (c.d.f.), force of mortality, and latent period for radiation-induced malignancies. It is demonstrated that correction for competing risks influences the shape of dose response curves, estimates of the latent period, and of the risk from ionizing radiations. The equivalence of the following concepts is demonstrated: force of mortality, hazard rate, and age or time specific incidence. This equivalence makes it possible to use procedures from reliability analysis and demography for radiation risk assessment. Two methods used by reliability analysts - hazard plotting and total time on test plots - are discussed in some detail and applied to characterize the hazard rate in radiation carcinogenesis. C.d.f.'s with increasing, decreasing, or constant hazard rate have different shapes and are shown to yield different dose-response curves for continuous irradiation. Absolute risk is shown to be a sound estimator only if the force of mortality is constant for the exposed and the control group. Dose-response relationships that use the absolute risk as a measure for the effect turn out to be special cases of dose-response relationships that measure the effect with cumulative incidence. (H.K.)

Evaluation of thermal risk assessment

International Nuclear Information System (INIS)

Loos, J.J.; Perry, E.S.

1993-01-01

Risk assessment was done in 1983 to estimate the ecological hazard of increasing the generating load and thermal output of an electric generating station. Subsequently, long-term monitoring in the vicinity of the station allowed verification of the predictions made in the risk assessment. This presentation will review the efficacy of early risk assessment methods in producing useful predictions from a resource management point of view. In 1984, the Chalk Point Generating facility of the Potomac Electric Power Company increased it's median generating load by 100%. Prior to this operational change, the Academy of Natural Sciences of Philadelphia synthesized site specific data, model predictions, and results from literature to assess the risk of additional waste heat to the Patuxent River subestuary of Chesapeake Bay. Risk was expressed as the number of days per year that various species of fish and the blue crab would be expected to avoid the discharge vicinity. Accuracy of these predictions is assessed by comparing observed fish and crab distributions and their observed frequencies of avoidance to those predicted. It is concluded that the predictions of this early risk assessment were sufficiently accurate to produce a reliable resource management decision

Integrated system reliability analysis

DEFF Research Database (Denmark)

Gintautas, Tomas; Sørensen, John Dalsgaard

Specific targets: 1) The report shall describe the state of the art of reliability and risk-based assessment of wind turbine components. 2) Development of methodology for reliability and risk-based assessment of the wind turbine at system level. 3) Describe quantitative and qualitative measures...

Assessing the reliability, predictive and construct validity of historical, clinical and risk management-20 (HCR-20) in Mexican psychiatric inpatients.

Science.gov (United States)

Sada, Andrea; Robles-García, Rebeca; Martínez-López, Nicolás; Hernández-Ramírez, Rafael; Tovilla-Zarate, Carlos-Alfonso; López-Munguía, Fernando; Suárez-Alvarez, Enrique; Ayala, Xochitl; Fresán, Ana

2016-08-01

Assessing dangerousness to gauge the likelihood of future violent behaviour has become an integral part of clinical mental health practice in forensic and non-forensic psychiatric settings, one of the most effective instruments for this being the Historical, Clinical and Risk Management-20 (HCR-20). To examine the HCR-20 factor structure in Mexican psychiatric inpatients and to obtain its predictive validity and reliability for use in this population. In total, 225 patients diagnosed with psychotic, affective or personality disorders were included. The HCR-20 was applied at hospital admission and violent behaviours were assessed during psychiatric hospitalization using the Overt Aggression Scale (OAS). Construct validity, predictive validity and internal consistency were determined. Violent behaviour remains more severe in patients classified in the high-risk group during hospitalization. Fifteen items displayed adequate communalities in the original designated domains of the HCR-20 and internal consistency of the instruments was high. The HCR-20 is a suitable instrument for predicting violence risk in Mexican psychiatric inpatients.

Reliability and maintainability assessment factors for reliable fault-tolerant systems

Science.gov (United States)

Bavuso, S. J.

1984-01-01

A long term goal of the NASA Langley Research Center is the development of a reliability assessment methodology of sufficient power to enable the credible comparison of the stochastic attributes of one ultrareliable system design against others. This methodology, developed over a 10 year period, is a combined analytic and simulative technique. An analytic component is the Computer Aided Reliability Estimation capability, third generation, or simply CARE III. A simulative component is the Gate Logic Software Simulator capability, or GLOSS. The numerous factors that potentially have a degrading effect on system reliability and the ways in which these factors that are peculiar to highly reliable fault tolerant systems are accounted for in credible reliability assessments. Also presented are the modeling difficulties that result from their inclusion and the ways in which CARE III and GLOSS mitigate the intractability of the heretofore unworkable mathematics.

Risk-based methods for reliability investments in electric power distribution systems

Energy Technology Data Exchange (ETDEWEB)

Alvehag, Karin

2011-07-01

Society relies more and more on a continuous supply of electricity. However, while under investments in reliability lead to an unacceptable number of power interruptions, over investments result in too high costs for society. To give incentives for a socio economically optimal level of reliability, quality regulations have been adopted in many European countries. These quality regulations imply new financial risks for the distribution system operator (DSO) since poor reliability can reduce the allowed revenue for the DSO and compensation may have to be paid to affected customers. This thesis develops a method for evaluating the incentives for reliability investments implied by different quality regulation designs. The method can be used to investigate whether socio economically beneficial projects are also beneficial for a profit-maximizing DSO subject to a particular quality regulation design. To investigate which reinvestment projects are preferable for society and a DSO, risk-based methods are developed. With these methods, the probability of power interruptions and the consequences of these can be simulated. The consequences of interruptions for the DSO will to a large extent depend on the quality regulation. The consequences for the customers, and hence also society, will depend on factors such as the interruption duration and time of occurrence. The proposed risk-based methods consider extreme outage events in the risk assessments by incorporating the impact of severe weather, estimating the full probability distribution of the total reliability cost, and formulating a risk-averse strategy. Results from case studies performed show that quality regulation design has a significant impact on reinvestment project profitability for a DSO. In order to adequately capture the financial risk that the DSO is exposed to, detailed riskbased methods, such as the ones developed in this thesis, are needed. Furthermore, when making investment decisions, a risk

Nuclear Computerized Library for Assessing Reactor Reliability (NUCLARR)

International Nuclear Information System (INIS)

Gilbert, B.G.; Reece, W.J.; Gertman, D.I.; Gilmore, W.E.; Galyean, W.J.

1990-12-01

The Nuclear Computerized Library for Assessing Reactor Reliability (NUCLARR) is an automated data base management system for processing and storing human error probability and hardware component failure data. The NUCLARR system software resides on an IBM (or compatible) personal computer. NUCLARR can furnish the end user with data inputs for both human and hardware reliability analysis in support of a variety of risk assessment activities. The NUCLARR system is documented in a five-volume series of reports. Volume 5: Data Manual provides a hard-copy representation of all data and related information available within the NUCLARR system software. This document is organized in three sections. Part 1 is the summary description, which presents an overview of the NUCLARR system and data processing procedures. Part 2 contains all data and information relevant to the human error probability (HEP) data side of NUCLARR. Data and information for the hardware component failure data (HCFD) side are presented in Part 3. 7 refs

Inter-rater reliability of an observation-based ergonomics assessment checklist for office workers.

Science.gov (United States)

Pereira, Michelle Jessica; Straker, Leon Melville; Comans, Tracy Anne; Johnston, Venerina

2016-12-01

To establish the inter-rater reliability of an observation-based ergonomics assessment checklist for computer workers. A 37-item (38-item if a laptop was part of the workstation) comprehensive observational ergonomics assessment checklist comparable to government guidelines and up to date with empirical evidence was developed. Two trained practitioners assessed full-time office workers performing their usual computer-based work and evaluated the suitability of workstations used. Practitioners assessed each participant consecutively. The order of assessors was randomised, and the second assessor was blinded to the findings of the first. Unadjusted kappa coefficients between the raters were obtained for the overall checklist and subsections that were formed from question-items relevant to specific workstation equipment. Twenty-seven office workers were recruited. The inter-rater reliability between two trained practitioners achieved moderate to good reliability for all except one checklist component. This checklist has mostly moderate to good reliability between two trained practitioners. Practitioner Summary: This reliable ergonomics assessment checklist for computer workers was designed using accessible government guidelines and supplemented with up-to-date evidence. Employers in Queensland (Australia) can fulfil legislative requirements by using this reliable checklist to identify and subsequently address potential risk factors for work-related injury to provide a safe working environment.

An approach for assessing ALWR passive safety system reliability

International Nuclear Information System (INIS)

Hake, T.M.

1991-01-01

Many of the advanced light water reactor (ALWR) concepts proposed for the next generation of nuclear power plants rely on passive rather than active systems to perform safety functions. Despite the reduced redundancy of the passive systems as compared to active systems in current plants, the assertion is that the overall safety of the plant is enhanced due to the much higher expected reliability of the passive systems. In order to investigate this assertion, a study is being conducted at Sandia National Laboratories to evaluate the reliability of ALWR passive safety features in the context of probabilistic risk assessment (PRA). The purpose of this paper is to provide a brief overview of the approach to this study. The quantification of passive system reliability is not as straightforward as for active systems, due to the lack of operating experience, and to the greater uncertainty in the governing physical phenomena. Thus, the adequacy of current methods for evaluating system reliability must be assessed, and alternatives proposed if necessary. For this study, the Westinghouse Advanced Passive 600 MWe reactor (AP600) was chosen as the advanced reactor for analysis, because of the availability of AP600 design information. This study compares the reliability of AP600 emergency cooling system with that of corresponding systems in a current generation reactor

Johnson Space Center's Risk and Reliability Analysis Group 2008 Annual Report

Science.gov (United States)

Valentine, Mark; Boyer, Roger; Cross, Bob; Hamlin, Teri; Roelant, Henk; Stewart, Mike; Bigler, Mark; Winter, Scott; Reistle, Bruce; Heydorn,Dick

2009-01-01

The Johnson Space Center (JSC) Safety & Mission Assurance (S&MA) Directorate s Risk and Reliability Analysis Group provides both mathematical and engineering analysis expertise in the areas of Probabilistic Risk Assessment (PRA), Reliability and Maintainability (R&M) analysis, and data collection and analysis. The fundamental goal of this group is to provide National Aeronautics and Space Administration (NASA) decisionmakers with the necessary information to make informed decisions when evaluating personnel, flight hardware, and public safety concerns associated with current operating systems as well as with any future systems. The Analysis Group includes a staff of statistical and reliability experts with valuable backgrounds in the statistical, reliability, and engineering fields. This group includes JSC S&MA Analysis Branch personnel as well as S&MA support services contractors, such as Science Applications International Corporation (SAIC) and SoHaR. The Analysis Group s experience base includes nuclear power (both commercial and navy), manufacturing, Department of Defense, chemical, and shipping industries, as well as significant aerospace experience specifically in the Shuttle, International Space Station (ISS), and Constellation Programs. The Analysis Group partners with project and program offices, other NASA centers, NASA contractors, and universities to provide additional resources or information to the group when performing various analysis tasks. The JSC S&MA Analysis Group is recognized as a leader in risk and reliability analysis within the NASA community. Therefore, the Analysis Group is in high demand to help the Space Shuttle Program (SSP) continue to fly safely, assist in designing the next generation spacecraft for the Constellation Program (CxP), and promote advanced analytical techniques. The Analysis Section s tasks include teaching classes and instituting personnel qualification processes to enhance the professional abilities of our analysts

Validity and inter-observer reliability of subjective hand-arm vibration assessments

NARCIS (Netherlands)

Coenen, P.; Formanoy, M.; Douwes, M.; Bosch, T.; Kraker, H. de

2014-01-01

Exposure to mechanical vibrations at work (e.g., due to handling powered tools) is a potential occupational risk as it may cause upper extremity complaints. However, reliable and valid assessment methods for vibration exposure at work are lacking. Measuring hand-arm vibration objectively is often

A heuristic-based approach for reliability importance assessment of energy producers

International Nuclear Information System (INIS)

Akhavein, A.; Fotuhi Firuzabad, M.

2011-01-01

Reliability of energy supply is one of the most important issues of service quality. On one hand, customers usually have different expectations for service reliability and price. On the other hand, providing different level of reliability at load points is a challenge for system operators. In order to take reasonable decisions and obviate reliability implementation difficulties, market players need to know impacts of their assets on system and load-point reliabilities. One tool to specify reliability impacts of assets is the criticality or reliability importance measure by which system components can be ranked based on their effect on reliability. Conventional methods for determination of reliability importance are essentially on the basis of risk sensitivity analysis and hence, impose prohibitive calculation burden in large power systems. An approach is proposed in this paper to determine reliability importance of energy producers from perspective of consumers or distribution companies in a composite generation and transmission system. In the presented method, while avoiding immense computational burden, the energy producers are ranked based on their rating, unavailability and impact on power flows in the lines connecting to the considered load points. Study results on the IEEE reliability test system show successful application of the proposed method. - Research highlights: → Required reliability level at load points is a concern in modern power systems. → It is important to assess reliability importance of energy producers or generators. → Generators can be ranked based on their impacts on power flow to a selected area. → Ranking of generators is an efficient tool to assess their reliability importance.

Human reliability

International Nuclear Information System (INIS)

Embrey, D.E.

1987-01-01

Concepts and techniques of human reliability have been developed and are used mostly in probabilistic risk assessment. For this, the major application of human reliability assessment has been to identify the human errors which have a significant effect on the overall safety of the system and to quantify the probability of their occurrence. Some of the major issues within human reliability studies are reviewed and it is shown how these are applied to the assessment of human failures in systems. This is done under the following headings; models of human performance used in human reliability assessment, the nature of human error, classification of errors in man-machine systems, practical aspects, human reliability modelling in complex situations, quantification and examination of human reliability, judgement based approaches, holistic techniques and decision analytic approaches. (UK)

Cumulative trauma disorders in the upper extremities: reliability of the postural and repetitive risk-factors index.

Science.gov (United States)

James, C P; Harburn, K L; Kramer, J F

1997-08-01

This study addresses test-retest reliability of the Postural and Repetitive Risk-Factors Index (PRRI) for work-related upper body injuries. This assessment was developed by the present authors. A repeated measures design was used to assess the test-retest reliability of a videotaped work-site assessment of subjects' movements. Ten heavy users of video display terminals (VDTs) from a local banking industry participated in the study. The 10 subjects' movements were videotaped for 2 hours on each of 2 separate days, while working on-site at their VDTs. The videotaped assessment, which utilized known postural risk factors for developing musculoskeletal disorder, pain, and discomfort in heavy VDT users (ie, repetitiveness, awkward and static postures, and contraction time), was called the PRRI. The videotaped movement assessments were subsequently analyzed in 15-minute sessions (five sessions per 2-hour videotape, which produced a total of 10 sessions over the 2 testing days), and each session was chosen randomly from the videotape. The subjects' movements were given a postural risk score according to the criteria in the PRRI. Each subject was therefore tested a total of 10 times (ie, 10 sessions), over two days. The maximum PRRI score for both sides of the body was 216 points. Reliability coefficients (RCs) for the PRRI scores were calculated, and the reliability of any one session met the minimum criterion for excellent reliability, which was .75. A two-way analysis of variance (ANOVA) confirmed that there was no statistically significant difference between sessions (p < .05). Calculations using the standard error of measurement (SEM) indicated that an individual tested once, on one day and with a PRRI score of 25, required a change of at least 8 points in order to be confident that a true change in score had occurred. The significant results from the reliability tests indicated that the PRRI was a reliable measurement tool that could be used by occupational health

A Mechanistic Reliability Assessment of RVACS and Metal Fuel Inherent Reactivity Feedbacks

Energy Technology Data Exchange (ETDEWEB)

Grabaskas, David; Brunett, Acacia J.; Passerini, Stefano; Grelle, Austin

2017-09-24

GE Hitachi Nuclear Energy (GEH) and Argonne National Laboratory (Argonne) participated in a two year collaboration to modernize and update the probabilistic risk assessment (PRA) for the PRISM sodium fast reactor. At a high level, the primary outcome of the project was the development of a next-generation PRA that is intended to enable risk-informed prioritization of safety- and reliability-focused research and development. A central Argonne task during this project was a reliability assessment of passive safety systems, which included the Reactor Vessel Auxiliary Cooling System (RVACS) and the inherent reactivity feedbacks of the metal fuel core. Both systems were examined utilizing a methodology derived from the Reliability Method for Passive Safety Functions (RMPS), with an emphasis on developing success criteria based on mechanistic system modeling while also maintaining consistency with the Fuel Damage Categories (FDCs) of the mechanistic source term assessment. This paper provides an overview of the reliability analyses of both systems, including highlights of the FMEAs, the construction of best-estimate models, uncertain parameter screening and propagation, and the quantification of system failure probability. In particular, special focus is given to the methodologies to perform the analysis of uncertainty propagation and the determination of the likelihood of violating FDC limits. Additionally, important lessons learned are also reviewed, such as optimal sampling methodologies for the discovery of low likelihood failure events and strategies for the combined treatment of aleatory and epistemic uncertainties.

The risk of bias in systematic reviews tool showed fair reliability and good construct validity.

Science.gov (United States)

Bühn, Stefanie; Mathes, Tim; Prengel, Peggy; Wegewitz, Uta; Ostermann, Thomas; Robens, Sibylle; Pieper, Dawid

2017-11-01

There is a movement from generic quality checklists toward a more domain-based approach in critical appraisal tools. This study aimed to report on a first experience with the newly developed risk of bias in systematic reviews (ROBIS) tool and compare it with A Measurement Tool to Assess Systematic Reviews (AMSTAR), that is, the most common used tool to assess methodological quality of systematic reviews while assessing validity, reliability, and applicability. Validation study with four reviewers based on 16 systematic reviews in the field of occupational health. Interrater reliability (IRR) of all four raters was highest for domain 2 (Fleiss' kappa κ = 0.56) and lowest for domain 4 (κ = 0.04). For ROBIS, median IRR was κ = 0.52 (range 0.13-0.88) for the experienced pair of raters compared to κ = 0.32 (range 0.12-0.76) for the less experienced pair of raters. The percentage of "yes" scores of each review of ROBIS ratings was strongly correlated with the AMSTAR ratings (r s  = 0.76; P = 0.01). ROBIS has fair reliability and good construct validity to assess the risk of bias in systematic reviews. More validation studies are needed to investigate reliability and applicability, in particular. Copyright © 2017 Elsevier Inc. All rights reserved.

Quantitative risk assessment of digitalized safety systems

Energy Technology Data Exchange (ETDEWEB)

Shin, Sung Min; Lee, Sang Hun; Kang, Hym Gook [KAIST, Daejeon (Korea, Republic of); Lee, Seung Jun [UNIST, Ulasn (Korea, Republic of)

2016-05-15

A report published by the U.S. National Research Council indicates that appropriate methods for assessing reliability are key to establishing the acceptability of digital instrumentation and control (I and C) systems in safety-critical plants such as NPPs. Since the release of this issue, the methodology for the probabilistic safety assessment (PSA) of digital I and C systems has been studied. However, there is still no widely accepted method. Kang and Sung found three critical factors for safety assessment of digital systems: detection coverage of fault-tolerant techniques, software reliability quantification, and network communication risk. In reality the various factors composing digitalized I and C systems are not independent of each other but rather closely connected. Thus, from a macro point of view, a method that can integrate risk factors with different characteristics needs to be considered together with the micro approaches to address the challenges facing each factor.

Reliability and risk-based planning of operation and maintenance of offshore wind turbines

DEFF Research Database (Denmark)

Sørensen, John Dalsgaard; Florian, Mihai; Berzonskis, Arvydas

2016-01-01

costly (and safe), and it is important to include in the reliability assessment the information obtained during operation (from condition monitoring and inspections) and the maintenance performed (incl. repairs and replacements). The paper presents a risk-based approach for optimal planning of Operation...

Risk and reliability assessment for telecommunications networks

Energy Technology Data Exchange (ETDEWEB)

Wyss, G.D.; Schriner, H.K.; Gaylor, T.R.

1996-08-01

Sandia National Laboratories has assembled an interdisciplinary team to explore the applicability of probabilistic logic modeling (PLM) techniques to model network reliability for a wide variety of communications network architectures. The authors have found that the reliability and failure modes of current generation network technologies can be effectively modeled using fault tree PLM techniques. They have developed a ``plug-and-play`` fault tree analysis methodology that can be used to model connectivity and the provision of network services in a wide variety of current generation network architectures. They have also developed an efficient search algorithm that can be used to determine the minimal cut sets of an arbitrarily-interconnected (non-hierarchical) network without the construction of a fault tree model. This paper provides an overview of these modeling techniques and describes how they are applied to networks that exhibit hybrid network structures (i.e., a network in which some areas are hierarchical and some areas are not hierarchical).

Structural reliability analysis and seismic risk assessment

International Nuclear Information System (INIS)

Hwang, H.; Reich, M.; Shinozuka, M.

1984-01-01

This paper presents a reliability analysis method for safety evaluation of nuclear structures. By utilizing this method, it is possible to estimate the limit state probability in the lifetime of structures and to generate analytically the fragility curves for PRA studies. The earthquake ground acceleration, in this approach, is represented by a segment of stationary Gaussian process with a zero mean and a Kanai-Tajimi Spectrum. All possible seismic hazard at a site represented by a hazard curve is also taken into consideration. Furthermore, the limit state of a structure is analytically defined and the corresponding limit state surface is then established. Finally, the fragility curve is generated and the limit state probability is evaluated. In this paper, using a realistic reinforced concrete containment as an example, results of the reliability analysis of the containment subjected to dead load, live load and ground earthquake acceleration are presented and a fragility curve for PRA studies is also constructed

Reliability and risk analysis methods research plan

International Nuclear Information System (INIS)

1984-10-01

This document presents a plan for reliability and risk analysis methods research to be performed mainly by the Reactor Risk Branch (RRB), Division of Risk Analysis and Operations (DRAO), Office of Nuclear Regulatory Research. It includes those activities of other DRAO branches which are very closely related to those of the RRB. Related or interfacing programs of other divisions, offices and organizations are merely indicated. The primary use of this document is envisioned as an NRC working document, covering about a 3-year period, to foster better coordination in reliability and risk analysis methods development between the offices of Nuclear Regulatory Research and Nuclear Reactor Regulation. It will also serve as an information source for contractors and others to more clearly understand the objectives, needs, programmatic activities and interfaces together with the overall logical structure of the program

Ecotoxicological hazard and risk assessment of endocrine active substances.

Science.gov (United States)

Leopold, Annegaaike; Roberts, Mike; Matthiessen, Peter

2017-03-01

This collection of papers provides state-of-the-art science on a complex topic that has been challenging for scientists and regulators for a long time. The papers emanated from the Society of Environmental Toxicology and Chemistry (SETAC) Pellston Workshop ® Environmental Hazard and Risk Assessment Approaches for Endocrine-Active Substances (EHRA). Forty-eight international experts met in early February 2016 to discuss whether the environmental risks posed by endocrine-disrupting substances (EDS) can be reliably assessed. The primary conclusion of the workshop was that if data on environmental exposure, effects on sensitive species and life-stages, delayed effects, and effects at low concentrations are robust, initiating environmental risk assessment of EDS is scientifically sound and reliable. Integr Environ Assess Manag 2017;13:264-266. © 2016 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals, Inc. on behalf of Society of Environmental Toxicology & Chemistry (SETAC). © 2016 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals, Inc. on behalf of Society of Environmental Toxicology & Chemistry (SETAC).

Reliability of Instruments Measuring At-Risk and Problem Gambling Among Young Individuals

DEFF Research Database (Denmark)

Edgren, Robert; Castrén, Sari; Mäkelä, Marjukka

2016-01-01

This review aims to clarify which instruments measuring at-risk and problem gambling (ARPG) among youth are reliable and valid in light of reported estimates of internal consistency, classification accuracy, and psychometric properties. A systematic search was conducted in PubMed, Medline, and Psyc......Info covering the years 2009–2015. In total, 50 original research articles fulfilled the inclusion criteria: target age under 29 years, using an instrument designed for youth, and reporting a reliability estimate. Articles were evaluated with the revised Quality Assessment of Diagnostic Accuracy Studies tool....... Reliability estimates were reported for five ARPG instruments. Most studies (66%) evaluated the South Oaks Gambling Screen Revised for Adolescents. The Gambling Addictive Behavior Scale for Adolescents was the only novel instrument. In general, the evaluation of instrument reliability was superficial. Despite...

Software reliability assessment

International Nuclear Information System (INIS)

Barnes, M.; Bradley, P.A.; Brewer, M.A.

1994-01-01

The increased usage and sophistication of computers applied to real time safety-related systems in the United Kingdom has spurred on the desire to provide a standard framework within which to assess dependable computing systems. Recent accidents and ensuing legislation have acted as a catalyst in this area. One particular aspect of dependable computing systems is that of software, which is usually designed to reduce risk at the system level, but which can increase risk if it is unreliable. Various organizations have recognized the problem of assessing the risk imposed to the system by unreliable software, and have taken initial steps to develop and use such assessment frameworks. This paper relates the approach of Consultancy Services of AEA Technology in developing a framework to assess the risk imposed by unreliable software. In addition, the paper discusses the experiences gained by Consultancy Services in applying the assessment framework to commercial and research projects. The framework is applicable to software used in safety applications, including proprietary software. Although the paper is written with Nuclear Reactor Safety applications in mind, the principles discussed can be applied to safety applications in all industries

Critical Assessment of the Foundations of Power Transmission and Distribution Reliability Metrics and Standards.

Science.gov (United States)

Nateghi, Roshanak; Guikema, Seth D; Wu, Yue Grace; Bruss, C Bayan

2016-01-01

The U.S. federal government regulates the reliability of bulk power systems, while the reliability of power distribution systems is regulated at a state level. In this article, we review the history of regulating electric service reliability and study the existing reliability metrics, indices, and standards for power transmission and distribution networks. We assess the foundations of the reliability standards and metrics, discuss how they are applied to outages caused by large exogenous disturbances such as natural disasters, and investigate whether the standards adequately internalize the impacts of these events. Our reflections shed light on how existing standards conceptualize reliability, question the basis for treating large-scale hazard-induced outages differently from normal daily outages, and discuss whether this conceptualization maps well onto customer expectations. We show that the risk indices for transmission systems used in regulating power system reliability do not adequately capture the risks that transmission systems are prone to, particularly when it comes to low-probability high-impact events. We also point out several shortcomings associated with the way in which regulators require utilities to calculate and report distribution system reliability indices. We offer several recommendations for improving the conceptualization of reliability metrics and standards. We conclude that while the approaches taken in reliability standards have made considerable advances in enhancing the reliability of power systems and may be logical from a utility perspective during normal operation, existing standards do not provide a sufficient incentive structure for the utilities to adequately ensure high levels of reliability for end-users, particularly during large-scale events. © 2015 Society for Risk Analysis.

Structural reliability analysis applied to pipeline risk analysis

Energy Technology Data Exchange (ETDEWEB)

Gardiner, M. [GL Industrial Services, Loughborough (United Kingdom); Mendes, Renato F.; Donato, Guilherme V.P. [PETROBRAS S.A., Rio de Janeiro, RJ (Brazil)

2009-07-01

Quantitative Risk Assessment (QRA) of pipelines requires two main components to be provided. These are models of the consequences that follow from some loss of containment incident, and models for the likelihood of such incidents occurring. This paper describes how PETROBRAS have used Structural Reliability Analysis for the second of these, to provide pipeline- and location-specific predictions of failure frequency for a number of pipeline assets. This paper presents an approach to estimating failure rates for liquid and gas pipelines, using Structural Reliability Analysis (SRA) to analyze the credible basic mechanisms of failure such as corrosion and mechanical damage. SRA is a probabilistic limit state method: for a given failure mechanism it quantifies the uncertainty in parameters to mathematical models of the load-resistance state of a structure and then evaluates the probability of load exceeding resistance. SRA can be used to benefit the pipeline risk management process by optimizing in-line inspection schedules, and as part of the design process for new construction in pipeline rights of way that already contain multiple lines. A case study is presented to show how the SRA approach has recently been used on PETROBRAS pipelines and the benefits obtained from it. (author)

Integrated Reliability and Risk Analysis System (IRRAS)

International Nuclear Information System (INIS)

Russell, K.D.; McKay, M.K.; Sattison, M.B.; Skinner, N.L.; Wood, S.T.; Rasmuson, D.M.

1992-01-01

The Integrated Reliability and Risk Analysis System (IRRAS) is a state-of-the-art, microcomputer-based probabilistic risk assessment (PRA) model development and analysis tool to address key nuclear plant safety issues. IRRAS is an integrated software tool that gives the user the ability to create and analyze fault trees and accident sequences using a microcomputer. This program provides functions that range from graphical fault tree construction to cut set generation and quantification. Version 1.0 of the IRRAS program was released in February of 1987. Since that time, many user comments and enhancements have been incorporated into the program providing a much more powerful and user-friendly system. This version has been designated IRRAS 4.0 and is the subject of this Reference Manual. Version 4.0 of IRRAS provides the same capabilities as Version 1.0 and adds a relational data base facility for managing the data, improved functionality, and improved algorithm performance

Probabilistic assessment of pressure vessel and piping reliability

International Nuclear Information System (INIS)

Sundararajan, C.

1986-01-01

The paper presents a critical review of the state-of-the-art in probabilistic assessment of pressure vessel and piping reliability. First the differences in assessing the reliability directly from historical failure data and indirectly by a probabilistic analysis of the failure phenomenon are discussed and the advantages and disadvantages are pointed out. The rest of the paper deals with the latter approach of reliability assessment. Methods of probabilistic reliability assessment are described and major projects where these methods are applied for pressure vessel and piping problems are discussed. An extensive list of references is provided at the end of the paper

Nuclear Computerized Library for Assessing Reactor Reliability (NUCLARR): Summary description

International Nuclear Information System (INIS)

Gertman, D.I.; Gilmore, W.E.; Galyean, W.J.; Groh, M.R.; Gentillon, C.D.; Gilbert, B.G.; Reece, W.J.

1990-05-01

The Nuclear Computerized Library for Assessing Reactor Reliability (NUCLARR) is an automate data base management system for storing and processing human error probability and hardware component failure rate data. The NUCLARR system software resides on an IBM (or compatible) personal microcomputer. NUCLARR can be accessed by the end user to furnish data suitable for input in human and/or hardware reliability analysis to support a variety of risk assessment activities. The NUCLARR system is documented in a five-volume series of reports. This document Volume 1, of this series is the Summary Description, which presents an overview of the data management system, including a description of data collection, data qualification, data structure, and taxonomies. Programming activities, procedures for processing data, a user's guide, and hard copy data manual are presented in Volumes 2 through 5, NUREG/CR-4639

Assessing personality risks using the Surps for alcohol and other ...

African Journals Online (AJOL)

Assessing personality risks using the Surps for alcohol and other drug problems in Cape Town, South Africa. ... African Journal of Drug and Alcohol Studies ... In this crosssectional study, the Substance Use Risk Profile Scale (SURPS) was applied to measure these traits and assess the questionnaire's reliability from a ...

Developing safety performance functions incorporating reliability-based risk measures.

Science.gov (United States)

Ibrahim, Shewkar El-Bassiouni; Sayed, Tarek

2011-11-01

Current geometric design guides provide deterministic standards where the safety margin of the design output is generally unknown and there is little knowledge of the safety implications of deviating from these standards. Several studies have advocated probabilistic geometric design where reliability analysis can be used to account for the uncertainty in the design parameters and to provide a risk measure of the implication of deviation from design standards. However, there is currently no link between measures of design reliability and the quantification of safety using collision frequency. The analysis presented in this paper attempts to bridge this gap by incorporating a reliability-based quantitative risk measure such as the probability of non-compliance (P(nc)) in safety performance functions (SPFs). Establishing this link will allow admitting reliability-based design into traditional benefit-cost analysis and should lead to a wider application of the reliability technique in road design. The present application is concerned with the design of horizontal curves, where the limit state function is defined in terms of the available (supply) and stopping (demand) sight distances. A comprehensive collision and geometric design database of two-lane rural highways is used to investigate the effect of the probability of non-compliance on safety. The reliability analysis was carried out using the First Order Reliability Method (FORM). Two Negative Binomial (NB) SPFs were developed to compare models with and without the reliability-based risk measures. It was found that models incorporating the P(nc) provided a better fit to the data set than the traditional (without risk) NB SPFs for total, injury and fatality (I+F) and property damage only (PDO) collisions. Copyright © 2011 Elsevier Ltd. All rights reserved.

Reliability Assessment for Low-cost Unmanned Aerial Vehicles

Science.gov (United States)

Freeman, Paul Michael

Existing low-cost unmanned aerospace systems are unreliable, and engineers must blend reliability analysis with fault-tolerant control in novel ways. This dissertation introduces the University of Minnesota unmanned aerial vehicle flight research platform, a comprehensive simulation and flight test facility for reliability and fault-tolerance research. An industry-standard reliability assessment technique, the failure modes and effects analysis, is performed for an unmanned aircraft. Particular attention is afforded to the control surface and servo-actuation subsystem. Maintaining effector health is essential for safe flight; failures may lead to loss of control incidents. Failure likelihood, severity, and risk are qualitatively assessed for several effector failure modes. Design changes are recommended to improve aircraft reliability based on this analysis. Most notably, the control surfaces are split, providing independent actuation and dual-redundancy. The simulation models for control surface aerodynamic effects are updated to reflect the split surfaces using a first-principles geometric analysis. The failure modes and effects analysis is extended by using a high-fidelity nonlinear aircraft simulation. A trim state discovery is performed to identify the achievable steady, wings-level flight envelope of the healthy and damaged vehicle. Tolerance of elevator actuator failures is studied using familiar tools from linear systems analysis. This analysis reveals significant inherent performance limitations for candidate adaptive/reconfigurable control algorithms used for the vehicle. Moreover, it demonstrates how these tools can be applied in a design feedback loop to make safety-critical unmanned systems more reliable. Control surface impairments that do occur must be quickly and accurately detected. This dissertation also considers fault detection and identification for an unmanned aerial vehicle using model-based and model-free approaches and applies those

Reliability and safety engineering

CERN Document Server

Verma, Ajit Kumar; Karanki, Durga Rao

2016-01-01

Reliability and safety are core issues that must be addressed throughout the life cycle of engineering systems. Reliability and Safety Engineering presents an overview of the basic concepts, together with simple and practical illustrations. The authors present reliability terminology in various engineering fields, viz.,electronics engineering, software engineering, mechanical engineering, structural engineering and power systems engineering. The book describes the latest applications in the area of probabilistic safety assessment, such as technical specification optimization, risk monitoring and risk informed in-service inspection. Reliability and safety studies must, inevitably, deal with uncertainty, so the book includes uncertainty propagation methods: Monte Carlo simulation, fuzzy arithmetic, Dempster-Shafer theory and probability bounds. Reliability and Safety Engineering also highlights advances in system reliability and safety assessment including dynamic system modeling and uncertainty management. Cas...

Assessing the reliability of skilled performance

International Nuclear Information System (INIS)

Dougherty, E.M.; Collins, E.P.

1996-01-01

In some high-hazard military tasks, precision of motor skills is crucial to avoid a risk-sensitive drop or other mishap. Sparse data supports a basic level of reliability for this activity seemingly much lower than typical, individual action, slip-mode errors would yield. A typical occurrence failure rate seems to be of the order of 1 x 10 -5 per opportunity. A speculation is tendered that this represents a difference in kind; that the reliability of skills is a different taxon than previously called out in the typical scheme of human reliability

Reliability assessment of serviceability performance of braced retaining walls using a neural network approach

Science.gov (United States)

Goh, A. T. C.; Kulhawy, F. H.

2005-05-01

In urban environments, one major concern with deep excavations in soft clay is the potentially large ground deformations in and around the excavation. Excessive movements can damage adjacent buildings and utilities. There are many uncertainties associated with the calculation of the ultimate or serviceability performance of a braced excavation system. These include the variabilities of the loadings, geotechnical soil properties, and engineering and geometrical properties of the wall. A risk-based approach to serviceability performance failure is necessary to incorporate systematically the uncertainties associated with the various design parameters. This paper demonstrates the use of an integrated neural network-reliability method to assess the risk of serviceability failure through the calculation of the reliability index. By first performing a series of parametric studies using the finite element method and then approximating the non-linear limit state surface (the boundary separating the safe and failure domains) through a neural network model, the reliability index can be determined with the aid of a spreadsheet. Two illustrative examples are presented to show how the serviceability performance for braced excavation problems can be assessed using the reliability index.

Reliability assessment of aging structures subjected to gradual and shock deteriorations

International Nuclear Information System (INIS)

Wang, Cao; Zhang, Hao; Li, Quanwang

2017-01-01

Civil structures and infrastructure facilities are susceptible to deterioration posed by the effects of natural hazards and aggressive environmental conditions. These factors may increase the risk of service interruption of infrastructures, and should be taken into account when assessing the structural reliability during an infrastructure's service life. Modeling the resistance deterioration process reasonably is the basis for structural reliability analysis. In this paper, a novel model is developed for describing the deterioration of aging structures. The deterioration is a combination of two stochastic processes: the gradual deterioration posed by environmental effects and the shock deterioration caused by severe load attacks. The dependency of the deterioration magnitude on the load intensity is considered. The Gaussian copula function is employed to help construct the joint distribution of correlated random variables. Semi-analytical methods are developed to assess the structural failure time and the number of significant load events (shocks) to failure. Illustrative examples are presented to demonstrate the applicability of the proposed model in structural reliability analysis. Parametric studies are performed to investigate the role of deterioration-load correlation in structural reliability. - Highlights: • A new resistance deterioration model for aging structures is proposed. • Time-dependent reliability analysis methods incorporating the proposed deterioration model are developed. • Parametric studies are performed to investigate the role of deterioration-load correlation in structural reliability.

Ecological Risk Assessment of Genetically Modified Higher Plants (GMHP)

DEFF Research Database (Denmark)

Kjær, C.; Damgaard, C.; Kjellsson, G.

Preface This publication is a first version of a manual identifying the data needs for ecological risk assessment of genetically modified higher plants (GMHP). It is the intention of the authors to stimulate further discussion of what data are needed in order to conduct a proper ecological risk...... of the project Biotechnology: elements in environmental risk assessment of genetically modified plants. December 1999 Christian Kjær Introduction In ecological risk assessment of transgenic plants, information on a wide range of subjects is needed for an effective and reliable assessment procedure...... in the amendment to the directive. This report suggests a structured way to identify the type of data needed to perform a sound ecological risk assessment for genetically modified higher plants (GMHP). The identified data types are intended to support the evaluation of the following risks: risk of invasion...

A methodology for assessment seismic risk in PSAs

International Nuclear Information System (INIS)

Jae, Moo Sung

2001-01-01

This paper suggested a new framework for assessing seismic risk in PSAs. The framework used the concepts of requirement and achievement in the reliability physics. The quantified correlation which is a function of the requirement variable (hazard curve) and the achievement variable (fragility curve) results in a quantity, the unconditional frequency of exceeding a damage lelvel. This framework can be applied to any other external safety assessment, such as Fire and Flood Risk in PSAs

New Approaches to Reliability Assessment

DEFF Research Database (Denmark)

Ma, Ke; Wang, Huai; Blaabjerg, Frede

2016-01-01

of energy. New approaches for reliability assessment are being taken in the design phase of power electronics systems based on the physics-of-failure in components. In this approach, many new methods, such as multidisciplinary simulation tools, strength testing of components, translation of mission profiles......, and statistical analysis, are involved to enable better prediction and design of reliability for products. This article gives an overview of the new design flow in the reliability engineering of power electronics from the system-level point of view and discusses some of the emerging needs for the technology...

Assessing risk of bias in studies that evaluate health care interventions

DEFF Research Database (Denmark)

Page, Matthew J.; Boutron, Isabelle; Hansen, Camilla

2018-01-01

Methods to assess risk of bias in a way that is reliable, reproducible and transparent to readers, have evolved over time. Viswanathan et al. recently provided updated recommendations for assessing risk of bias in systematic reviews of health care interventions. We comment on their recommendations...

INSTRUMENTS OF HIGH RISK SEXUAL BEHAVIOR ASSESSMENT: A SYSTEMATIC REVIEW.

Science.gov (United States)

Mirzaei, Mojtaba; Ahmadi, Khodabakhsh; Saadat, Seyed-Hassan; Ramezani, Mohammad Arash

2016-02-01

Sexual behavior is a complex activity affecting all aspects of human's life. Risky sexual behaviors impose negative outcomes on family, relationships and health. Unsafe sex is the second most leading cause of disability adjusted life years worldwide. Valid and reliable tools for assessment of risky sexual behaviors are necessary for implementing preventive measures. we searched Medline and the Cochrane Library of Systematic Reviews, with the keywords of "risky sexual behavior assessment", "sexual risk assessment", "high risk sexual behavior", "sexual risk taking". By reviewing references of the articles, some complementary studies were added. Assessment can be performed by questionnaire or non-questionnaire instruments. Questionnaires vary depending on their target population, evaluation of risky sexual behavior as a whole or focusing on an associated risk factor. In order to avoid usual biases in self reports, objective biomarker assessment of unprotected sex are employed. These markers include prostate specific antigen, chromosome Y DNA and Seminogelin. Risky sexual behavior can be assessed by various subjective and objective methods. While self-reports are more feasible, objective methods offer a higher degree of reliability. Further studies for finding more feasible methods of using biomarkers are recommended.

Probabilistic risk assessment course documentation. Volume 3. System reliability and analysis techniques, Session A - reliability

International Nuclear Information System (INIS)

Lofgren, E.V.

1985-08-01

This course in System Reliability and Analysis Techniques focuses on the quantitative estimation of reliability at the systems level. Various methods are reviewed, but the structure provided by the fault tree method is used as the basis for system reliability estimates. The principles of fault tree analysis are briefly reviewed. Contributors to system unreliability and unavailability are reviewed, models are given for quantitative evaluation, and the requirements for both generic and plant-specific data are discussed. Also covered are issues of quantifying component faults that relate to the systems context in which the components are embedded. All reliability terms are carefully defined. 44 figs., 22 tabs

The reliability-quality relationship for quality systems and quality risk management.

Science.gov (United States)

Claycamp, H Gregg; Rahaman, Faiad; Urban, Jason M

2012-01-01

Engineering reliability typically refers to the probability that a system, or any of its components, will perform a required function for a stated period of time and under specified operating conditions. As such, reliability is inextricably linked with time-dependent quality concepts, such as maintaining a state of control and predicting the chances of losses from failures for quality risk management. Two popular current good manufacturing practice (cGMP) and quality risk management tools, failure mode and effects analysis (FMEA) and root cause analysis (RCA) are examples of engineering reliability evaluations that link reliability with quality and risk. Current concepts in pharmaceutical quality and quality management systems call for more predictive systems for maintaining quality; yet, the current pharmaceutical manufacturing literature and guidelines are curiously silent on engineering quality. This commentary discusses the meaning of engineering reliability while linking the concept to quality systems and quality risk management. The essay also discusses the difference between engineering reliability and statistical (assay) reliability. The assurance of quality in a pharmaceutical product is no longer measured only "after the fact" of manufacturing. Rather, concepts of quality systems and quality risk management call for designing quality assurance into all stages of the pharmaceutical product life cycle. Interestingly, most assays for quality are essentially static and inform product quality over the life cycle only by being repeated over time. Engineering process reliability is the fundamental concept that is meant to anticipate quality failures over the life cycle of the product. Reliability is a well-developed theory and practice for other types of manufactured products and manufacturing processes. Thus, it is well known to be an appropriate index of manufactured product quality. This essay discusses the meaning of reliability and its linkages with quality

Enabling More than Moore: Accelerated Reliability Testing and Risk Analysis for Advanced Electronics Packaging

Science.gov (United States)

Ghaffarian, Reza; Evans, John W.

2014-01-01

For five decades, the semiconductor industry has distinguished itself by the rapid pace of improvement in miniaturization of electronics products-Moore's Law. Now, scaling hits a brick wall, a paradigm shift. The industry roadmaps recognized the scaling limitation and project that packaging technologies will meet further miniaturization needs or ak.a "More than Moore". This paper presents packaging technology trends and accelerated reliability testing methods currently being practiced. Then, it presents industry status on key advanced electronic packages, factors affecting accelerated solder joint reliability of area array packages, and IPC/JEDEC/Mil specifications for characterizations of assemblies under accelerated thermal and mechanical loading. Finally, it presents an examples demonstrating how Accelerated Testing and Analysis have been effectively employed in the development of complex spacecraft thereby reducing risk. Quantitative assessments necessarily involve the mathematics of probability and statistics. In addition, accelerated tests need to be designed which consider the desired risk posture and schedule for particular project. Such assessments relieve risks without imposing additional costs. and constraints that are not value added for a particular mission. Furthermore, in the course of development of complex systems, variances and defects will inevitably present themselves and require a decision concerning their disposition, necessitating quantitative assessments. In summary, this paper presents a comprehensive view point, from technology to systems, including the benefits and impact of accelerated testing in offsetting risk.

ASSESSMENT OF RELIABILITY AND RISK DEGREE FOR ACCIDENT INITIATION AT SLIME STORAGES OF 4th MINING ADMINISTRATION, JSC “BELARUSKALI”

Directory of Open Access Journals (Sweden)

P. M. Bohaslauchyk

2016-01-01

Full Text Available Definition of reliability for dams of slime storage embankment is given on the basis of reliability theory and characteristics of reliability and their analysis are presented in the paper. The paper specifies qualitative indices for earth dams which are subdivided in two groups: applicability factors and structural reliability factors. A short analysis of all possible causes for accident initiation at earth dams has been made and the analysis has permitted to pinpoint eleven main objects for diagnosis for slime storage dams. In order to assess risk degree of accident initiation at JSC “Belaruskali” slime storages all possible causes of emergency cases and their probability of occurrence have been analyzed in the paper. The paper acknowledges the fact that dam malfunction is possible, as a rule, due to violation of operational rules and regulations. Main parameters of slime storage state which are to be controlled regularly in the process of its operation have been noted in the paper. Observation results over slime storages, calculations of dam slope stability for normal operation (a principal calculation case and operating irregularities in water seals (a special calculation case. As a stability margin factor is close to 1.0 for a special calculation case, an extreme position of depression curve has been determined for all design sections. It has been recommended to carry out a constant control over its position, and in the case when it reaches its peak value it is necessary to undertake appropriate measures in order to reduce its value. Final expert estimations on probability of accident initiation at the investigated slime storage dams of the 4th Mining Administration, JSC “Belaruskali” have been prepared on the basis of the analysis comprising all the required factors. A conclusion has been made about low risk degree of their destruction.

Technologies for Assessing Behavioral and Cognitive Markers of Suicide Risk

Science.gov (United States)

2017-10-01

assessing behavioral and cognitive markers of risk for suicide among U.S. Army National Guard personnel. Journal of Environmental Research and Public Policy...effective ways to prevent injury and death from suicide • No reliable method for predicting suicide risk in military personnel • Behavioral (e.g...AWARD NUMBER: W81XWH-15-1-0632 TITLE: Technologies for Assessing Behavioral and Cognitive Markers of Suicide Risk PRINCIPAL INVESTIGATOR: Brian

Mercury emissions from flooded soils and sediments in Germany are an underestimated problem: challenges for reliable risk assessments and management strategies

Directory of Open Access Journals (Sweden)

Rinklebe J.

2013-04-01

Full Text Available Environmental pollution by mercury is a world-wide problem. Particularly floodplain ecosystems are frequently affected. One example is the Elbe River in Germany and its catchment areas; large amounts of Hg from a range of anthropogenic and geogenic sources have been accumulated in the soils of these floodplains. They serve as sink for Hg originating from the surface water of adjacent river. Today, the vastly elevated Hg contents of the floodplain soils at the Elbe River often exceed even the action values of the German Soil Conservation Law. This is especially important as Hg polluted areas at the Elbe River achieve several hundred square kilometres. Thus, authorities are coerced by law to conduct an appropriate risk assessment and to implement practical actions to eliminate or reduce environmental problems. A reliable risk assessment particularly with view to organisms (vegetation as green fodder and hay production, grazing and wild animals to avoid the transfer of Hg into the human food chain, requires an authentic determination of Hg fluxes and their dynamics since gaseous emissions from soil to atmosphere are an important pathway of Hg. However, reliable estimates of Hg fluxes from the highly polluted floodplain soils at the Elbe River and its tributaries, and its influencing factors are scarce. For this purpose, we have developed a new method to determine mercury emissions from soils at various sites. Our objectives were i to quantify seasonal variations of total gaseous mercury (TGM fluxes for floodplain soils at the Elbe River, ii to provide insights into physico-chemical processes regulating these TGM fluxes, and iii to quantify the impacts of the controlling factors soil temperature and soil water content on Hg volatilization from a typical contaminated floodplain soil within soil microcosm experiments under various controlled temperature and moisture conditions. Our study provides insight into TGM emissions from highly Hg

Assessing reliability in energy supply systems

International Nuclear Information System (INIS)

McCarthy, Ryan W.; Ogden, Joan M.; Sperling, Daniel

2007-01-01

Reliability has always been a concern in the energy sector, but concerns are escalating as energy demand increases and the political stability of many energy supply regions becomes more questionable. But how does one define and measure reliability? We introduce a method to assess reliability in energy supply systems in terms of adequacy and security. It derives from reliability assessment frameworks developed for the electricity sector, which are extended to include qualitative considerations and to be applicable to new energy systems by incorporating decision-making processes based on expert opinion and multi-attribute utility theory. The method presented here is flexible and can be applied to any energy system. To illustrate its use, we apply the method to two hydrogen pathways: (1) centralized steam reforming of imported liquefied natural gas with pipeline distribution of hydrogen, and (2) on-site electrolysis of water using renewable electricity produced independently from the electricity grid

Psychometric properties of the Blood-borne Virus Transmission Risk Assessment Questionnaire (BBV-TRAQ).

Science.gov (United States)

Fry, Craig L; Lintzeris, Nick

2003-02-01

To develop a standard measure of blood-borne virus transmission risk behaviour, and examine the underlying psychometric properties. The Blood-borne Virus Transmission Risk Assessment Questionnaire (BBV-TRAQ) was developed over three consecutive phases of the original BBV-TRAQ study in adherence to classical scale development procedures, culminating in the recruitment of a development sample of current injecting drug users via convenience and snowball sampling. Needle and syringe programmes (NSPs), medical clinics, alcohol/drug agencies, peer-based and outreach organizations across inner and outer metropolitan Melbourne. Two hundred and nine current injecting drug users. The mean age was 27 years, 68% were male, 65% unemployed, 36% with prison history and 25% in methadone maintenance. BBV-TRAQ items cover specific injecting, sexual and skin penetration risk practices. BBV-TRAQ characteristics were assessed via measures of internal and test-retest reliability; collateral validation; and principal components analyses. The BBV-TRAQ has satisfactory psychometric properties. Internal (a=0.87), test-retest (r=0.84) and inter-observer reliability results were high, suggesting that the instrument provides a reliable measure of BBV risk behaviour and is reliable over time and across interviewers. A principal components analysis with varimax rotation produced a parsimonious factor solution despite modest communality, and indicated that three factors (injecting, sex and skin penetration/hygiene risks) are required to describe BBV risk behaviour. The BBV-TRAQ is reliable and represents the first risk assessment tool to incorporate sufficient coverage of injecting, sex and other skin penetration risk practices to be considered truly content valid. The questionnaire is indicated for use in addictions research, clinical, peer education and BBV risk behaviour surveillance settings.

Risk assessment techniques for industrial installations

International Nuclear Information System (INIS)

Croitoru, C.; Dumitrescu, M.; Preda, I.; Stefanescu, I.; Titescu, G.

1995-01-01

This paper presents a risk analysis which concerns the following stages: identification of the initiation events, evaluation of the occurrence frequency of different accident sequences, assessment of human, economical, and environmental consequences, risk assessment and management. The study of the accident sequences subsequent to an initiation event was achieved by the event tree method. Also, there were developed methods based on mathematical models of installations which take into account reliability data, data concerning the exploitation history, and data referring to the human factor effects in the installation operation. These methods were used for the determination of occurrence frequencies of hydrogen sulfide emission accidents in the heavy water production installations

Evolutionary leap in large-scale flood risk assessment needed

OpenAIRE

Vorogushyn, Sergiy; Bates, Paul D.; de Bruijn, Karin; Castellarin, Attilio; Kreibich, Heidi; Priest, Sally J.; Schröter, Kai; Bagli, Stefano; Blöschl, Günter; Domeneghetti, Alessio; Gouldby, Ben; Klijn, Frans; Lammersen, Rita; Neal, Jeffrey C.; Ridder, Nina

2018-01-01

Current approaches for assessing large-scale flood risks contravene the fundamental principles of the flood risk system functioning because they largely ignore basic interactions and feedbacks between atmosphere, catchments, river-floodplain systems and socio-economic processes. As a consequence, risk analyses are uncertain and might be biased. However, reliable risk estimates are required for prioritizing national investments in flood risk mitigation or for appraisal and management of insura...

Assessment of physical server reliability in multi cloud computing system

Science.gov (United States)

Kalyani, B. J. D.; Rao, Kolasani Ramchand H.

2018-04-01

Business organizations nowadays functioning with more than one cloud provider. By spreading cloud deployment across multiple service providers, it creates space for competitive prices that minimize the burden on enterprises spending budget. To assess the software reliability of multi cloud application layered software reliability assessment paradigm is considered with three levels of abstractions application layer, virtualization layer, and server layer. The reliability of each layer is assessed separately and is combined to get the reliability of multi-cloud computing application. In this paper, we focused on how to assess the reliability of server layer with required algorithms and explore the steps in the assessment of server reliability.

A model for assessing human cognitive reliability in PRA studies

International Nuclear Information System (INIS)

Hannaman, G.W.; Spurgin, A.J.; Lukic, Y.

1985-01-01

This paper summarizes the status of a research project sponsored by EPRI as part of the Probabilistic Risk Assessment (PRA) technology improvement program and conducted by NUS Corporation to develop a model of Human Cognitive Reliability (HCR). The model was synthesized from features identified in a review of existing models. The model development was based on the hypothesis that the key factors affecting crew response times are separable. The inputs to the model consist of key parameters the values of which can be determined by PRA analysts for each accident situation being assessed. The output is a set of curves which represent the probability of control room crew non-response as a function of time for different conditions affecting their performance. The non-response probability is then a contributor to the overall non-success of operating crews to achieve a functional objective identified in the PRA study. Simulator data and some small scale tests were utilized to illustrate the calibration of interim HCR model coefficients for different types of cognitive processing since the data were sparse. The model can potentially help PRA analysts make human reliability assessments more explicit. The model incorporates concepts from psychological models of human cognitive behavior, information from current collections of human reliability data sources and crew response time data from simulator training exercises

How simulation of failure risk can improve structural reliability - application to pressurized components and pipes

OpenAIRE

Cioclov, Dimitru Dragos

2013-01-01

Probabilistic methods for failure risk assessment are introduced, with reference to load carrying structures, such as pressure vessels (PV) and components of pipes systems. The definition of the failure risk associated with structural integrity is made in the context of the general approach to structural reliability. Sources of risk are summarily outlined with emphasis on variability and uncertainties (V&U) which might be encountered in the analysis. To highlight the problem, in its practical...

Reliability of a Skin Diagnostic Device in Assessing Hydration and Erythema.

Science.gov (United States)

Huimin, Koh; Rowledge, Alexandra M; Borzdynski, Caroline J; Miller, Charne; Frescos, Nicoletta; McKenzie, Gayle; Perry, Elizabeth; McGuiness, William

2017-10-01

To examine the reliability of a skin diagnostic device, the SD202 (Courage+Khazaka GmBH, Cologne, Germany), in assessing hydration and erythema of periwound skin and pressure injury-prone areas. Intrarater reliabilities from 3 cross-sectional and prospective studies are reported. Patients attending an outpatient, nurse-led wound dressing clinic (n = 16), a podiatrist-led high-risk foot clinic (n = 17), and residents (n = 38) at a single residential aged-care facility. Skin hydration and erythema levels assessed using the SD202. High internal consistency was maintained for consecutive skin hydration and erythema measures at a single point on the venous leg ulcer periwound (α > .996 and α > .970 for hydration and erythema, respectively) and for the pressure-prone areas of the sacrum (α > .916), right (α > .994) and left (α > .967) ischium, right (α > .989) and left (α > .916) trochanter, right (α > .985) and left (α > .992) calcaneus, and right (α > .991) and left (α > .990) lateral malleolus. High consistency was also found for the measures obtained at 4 different locations around the periwound for the venous leg ulcer (α > .935 and α > .870 for hydration and erythema, respectively). In diabetic foot ulcer assessment, acceptable internal consistency of hydration measures around the periwound was observed (α > .634). Internal consistency of erythema measures was variable, ranging from low to high reliability, particularly among predebridement measures. Using the protocols outlined in this study, the SD202 demonstrates high reliability for assessing skin hydration and erythema levels. It is possible that the SD202 can be used in clinical practice as an appropriate tool for skin hydration and erythema assessment.

Establishing the Appropriate Attributes in Current Human Reliability Assessment Techniques for Nuclear Safety

International Nuclear Information System (INIS)

Bowie, Jane; Munley, Gary; Dang, Vinh; Wreathall, John; Bye, Andreas; Cooper, Susan; Marble, Julie; Peters, Sean; Xing, Jing; Fauchille, Veronique; Fiset, Jean Yves; Haage, Monica; Johanson, Gunnar; Jung, Won Dae; Kim, Jaewhan; Lee, Seung Jung; Kubicek, Jan; Le Bot, Pierre; Pesme, Helene; Preischl, Wolfgang; Salway, Alice; Amri, Abdallah; Lamarre, Greg; White, Andrew; )

2015-03-01

This report presents the results of a joint task of the Working Groups on Risk Assessment (WGRISK) and on Human and Organisational Factors (WGHOF) of the OECD/NEA CSNI, to identify desirable attributes of Human Reliability Assessment (HRA) methods, and to evaluate a range of HRA methods used in OECD member countries against those attributes. The purpose of this project is to provide information that will support regulators and operators of nuclear facilities when making judgements about the appropriateness of HRA methods for conducting assessments in support of Probabilistic Safety Assessments (PSA). The task was performed by an international team of Human Factors, HRA and PSA experts from a broad range of OECD member countries. As in other reviews of HRA methods, the study did not set out to recommend or promote the use of any particular HRA method. Rather the study aims to identify the strengths and limitations of commonly used and developing methods to aid those responsible for production of HRAs in selecting appropriate tools for specific HRA applications. The study also aims to assist regulators when making judgements on the appropriateness of the application of an HRA technique within nuclear-related probabilistic safety assessments. The report is aimed at practitioners in the field of human reliability assessment, human factors, and risk assessment more generally

Nuclear Computerized Library for Assessing Reactor Reliability (NUCLARR): Data manual

International Nuclear Information System (INIS)

Gilbert, B.G.; Reece, W.J.; Gertman, D.I.; Gilmore, W.E.; Galyean, W.J.

1990-12-01

The Nuclear Computerized Library for Assessing Reactor Reliability (NUCLARR) is an automated data base management system for processing and storing human error probability and hardware component failure data. The NUCLARR system software resides on an IBM (or compatible) personal computer. NUCLARR can furnish the end user with data inputs for both human and hardware reliability analysis in support of a variety of risk assessment activities. The NUCLARR system is documented is a five-volume series of reports. Volume V: Data Manual provides a hard-copy representation of all data and related information available within the NUCLARR system software. This document is organized in three sections. Part 1 is the summary description, which presents an overview of the NUCLARR system and data processing procedures. Part 2 contains all data and information relevant to the human error probability (HEP) data side of NUCLARR. Data and information for the hardware component failure data (HCFD) side are presented in Part 3. 7 refs

Nuclear Computerized Library for Assessing Reactor Reliability (NUCLARR): Data manual

International Nuclear Information System (INIS)

Gilbert, B.G.; Reece, W.J.; Gertman, D.I.; Gilmore, W.E.; Galyean, W.J.

1990-12-01

The Nuclear Computerized Library for Assessing Reactor Reliability (NUCLARR) is an automated data base management system for processing and storing human error probability and hardware component failure data. The NUCLARR system software resides on an IBM (or compatible) personal computer. NUCLARR can furnish the end user with data inputs for both human and hardware reliability analysis in support of a variety of risk assessment activities. The NUCLARR system is documented in a five-volume series of reports. Volume V: Data Manual provides a hard-copy representation of all data and related information available within the NUCLARR system software. This document is organized in three sections. Part 1 is the summary description, which presents an overview of the NUCLARR system and data processing procedures. Part 2 contains all data and information relevant to the human error probability (HEP) side of NUCLARR. Data and information for the hardware component failure data (HCFD) side are presented in Part 3. 7 refs., 1 fig

Dynamic reliability and risk assessment of the accident localization system of the Ignalina NPP RBMK-1500 reactor

International Nuclear Information System (INIS)

Kopustinskas, V.; Augutis, J.; Rimkevicius, S.

2005-01-01

The paper presents reliability and risk analysis of the RBMK-1500 reactor accident localization system (ALS) (confinement), which prevents radioactive releases to the environment. Reliability of the system was estimated and compared by two methods: the conventional fault tree method and an innovative dynamic reliability model, based on stochastic differential equations. Frequency of radioactive release through ALS was also estimated. The results of the study indicate that conventional fault tree modeling techniques in this case apply high degree of conservatism in the system reliability estimates. One of the purposes of the ALS reliability study was to demonstrate advantages of the dynamic reliability analysis against the conventional fault/event tree methods. The Markovian framework to deal with dynamic aspects of system behavior is presented. Although not analyzed in detail, the framework is also capable of accounting for non-constant component failure rates. Computational methods are proposed to solve stochastic differential equations, including analytical solution, which is possible only for relatively small and simple systems. Other numerical methods, like Monte Carlo and numerical schemes of differential equations are analyzed and compared. The study is finalized with concluding remarks regarding both the studied system reliability and computational methods used

Development, reliability, and validity testing of Toddler NutriSTEP: a nutrition risk screening questionnaire for children 18-35 months of age.

Science.gov (United States)

Randall Simpson, Janis; Gumbley, Jillian; Whyte, Kylie; Lac, Jane; Morra, Crystal; Rysdale, Lee; Turfryer, Mary; McGibbon, Kim; Beyers, Joanne; Keller, Heather

2015-09-01

Nutrition is vital for optimal growth and development of young children. Nutrition risk screening can facilitate early intervention when followed by nutritional assessment and treatment. NutriSTEP (Nutrition Screening Tool for Every Preschooler) is a valid and reliable nutrition risk screening questionnaire for preschoolers (aged 3-5 years). A need was identified for a similar questionnaire for toddlers (aged 18-35 months). The purpose was to develop a reliable and valid Toddler NutriSTEP. Toddler NutriSTEP was developed in 4 phases. Content and face validity were determined with a literature review, parent focus groups (n = 6; 48 participants), and experts (n = 13) (phase A). A draft questionnaire was refined with key intercept interviews of 107 parents/caregivers (phase B). Test-retest reliability (phase C), based on intra-class correlations (ICC), Kappa (κ) statistics, and Wilcoxon tests was assessed with 133 parents/caregivers. Criterion validity (phase D) was assessed using Receiver Operating Characteristic (ROC) curves by comparing scores on the Toddler NutriSTEP to a comprehensive nutritional assessment of 200 toddlers with a registered dietitian (RD). The Toddler NutriSTEP was reliable between 2 administrations (ICC = 0.951, F = 20.53, p Toddler NutriSTEP were correlated (r = 0.67, p Toddler NutriSTEP questionnaire is both reliable and valid for screening for nutritional risk in toddlers.

Psychometric validation of the Chinese version of the Johns Hopkins Fall Risk Assessment Tool for older Chinese inpatients.

Science.gov (United States)

Zhang, Junhong; Wang, Min; Liu, Yu

2016-10-01

To culturally adapt and evaluate the reliability and validity of the Chinese version of the Johns Hopkins Fall Risk Assessment Tool among older inpatients in the mainland of China. Patient falls are an important safety consideration within hospitals among older inpatients. Nurses need specific risk assessment tools for older inpatients to reliably identify at-risk populations and guide interventions that highlight fixable risk factors for falls and consequent injuries. In China, a few tools have been developed to measure fall risk. However, they lack the solid psychometric development necessary to establish their validity and reliability, and they are not widely used for elderly inpatients. A cross-sectional study. A convenient sampling was used to recruit 201 older inpatients from two tertiary-level hospitals in Beijing and Xiamen, China. The Johns Hopkins Fall Risk Assessment Tool was translated using forward and backward translation procedures and was administered to these 201 older inpatients. Reliability of the tool was calculated by inter-rater reliability and Cronbach's alpha. Validity was analysed through content validity index and construct validity. The Inter-rater reliability of Chinese version of Johns Hopkins Fall Risk Assessment Tool was 97·14% agreement with Cohen's Kappa of 0·903. Cronbach's α was 0·703. Content of Validity Index was 0·833. Two factors represented intrinsic and extrinsic risk factors were explored that together explained 58·89% of the variance. This study provided evidence that Johns Hopkins Fall Risk Assessment Tool is an acceptable, valid and reliable tool to identify older inpatients at risk of falls and falls with injury. Further psychometric testing on criterion validity and evaluation of its advanced utility in geriatric clinical settings are warranted. The Chinese version of Johns Hopkins Fall Risk Assessment Tool may be useful for health care personnel to identify older Chinese inpatients at risk of falls and falls

Systems reliability analysis: applications of the SPARCS System-Reliability Assessment Computer Program

International Nuclear Information System (INIS)

Locks, M.O.

1978-01-01

SPARCS-2 (Simulation Program for Assessing the Reliabilities of Complex Systems, Version 2) is a PL/1 computer program for assessing (establishing interval estimates for) the reliability and the MTBF of a large and complex s-coherent system of any modular configuration. The system can consist of a complex logical assembly of independently failing attribute (binomial-Bernoulli) and time-to-failure (Poisson-exponential) components, without regard to their placement. Alternatively, it can be a configuration of independently failing modules, where each module has either or both attribute and time-to-failure components. SPARCS-2 also has an improved super modularity feature. Modules with minimal-cut unreliabiliy calculations can be mixed with those having minimal-path reliability calculations. All output has been standardized to system reliability or probability of success, regardless of the form in which the input data is presented, and whatever the configuration of modules or elements within modules

Reliability risks during the transition to competitive electricity markets

International Nuclear Information System (INIS)

Hughes, J.P.

2005-01-01

The Electricity Consumers Resource Council (ELCON) is a U.S. association representing industrial consumers of electricity, and is a long-standing advocate of competition in the electric power industry. However, because a reliable grid is necessary to support competitive wholesale markets, ELCON believes that the transmission system is an essential facility that must remain regulated. The initiatives discussed in this white paper represent significant steps that the National Electric Reliability Council (NERC) and the industry have taken to improve reliability in a competitive and restructured electric industry. Strategic manoeuvres of incumbent utilities to maintain market share were evaluated, as well as discrimination against potential competitors. It was suggested that, occasionally, indecisive federal policies have been taken advantage of by utilities. The unintended consequences of state restructuring policies that allow utilities to over-earn their revenue requirements were reviewed. NERC reliability standards will remain unenforceable until a new Electricity Reliability Organization has been certified. Flawed market designs and inadequate market power mitigation, as well as the financial distress of merchant generators, pose considerable risks. It was suggested that these risks could trigger transmission loading relief incidents, local outages or widespread outages. In the absence of mandatory reliability standards with penalties, and complementary market rules for mitigating generation and transmission market power, economic incentives will encourage other forms of opportunistic behavior that may be the root cause of other outages. Public concern regarding these risks to grid reliability may result in lost public support for competitive electricity markets. Proposed solutions include the certification of a new Electric Reliability Organization to establish and enforce mandatory reliability standards, and granting the Federal Energy Regulatory Commission

A Hierarchal Risk Assessment Model Using the Evidential Reasoning Rule

Directory of Open Access Journals (Sweden)

Xiaoxiao Ji

2017-02-01

Full Text Available This paper aims to develop a hierarchical risk assessment model using the newly-developed evidential reasoning (ER rule, which constitutes a generic conjunctive probabilistic reasoning process. In this paper, we first provide a brief introduction to the basics of the ER rule and emphasize the strengths for representing and aggregating uncertain information from multiple experts and sources. Further, we discuss the key steps of developing the hierarchical risk assessment framework systematically, including (1 formulation of risk assessment hierarchy; (2 representation of both qualitative and quantitative information; (3 elicitation of attribute weights and information reliabilities; (4 aggregation of assessment information using the ER rule and (5 quantification and ranking of risks using utility-based transformation. The proposed hierarchical risk assessment framework can potentially be implemented to various complex and uncertain systems. A case study on the fire/explosion risk assessment of marine vessels demonstrates the applicability of the proposed risk assessment model.

Preliminary investigation on reliability assessment of passive safety system

International Nuclear Information System (INIS)

Huang Changfan; Kuang Bo

2012-01-01

The reliability evaluation of passive safety system plays an important part in probabilistic safety assessment (PSA) of nuclear power plant applying passive safety design, which depends quantitatively on reliabilities of passive safety system. According to the object of reliability assessment of passive safety system, relevant parameters are identified. Then passive system behavior during accident scenarios are studied. A practical example of this method is given for the case of reliability assessment of AP1000 passive heat removal system in loss of normal feedwater accident. Key and design parameters of PRHRS are identified and functional failure criteria are established. Parameter combinations acquired by Latin hyper~ cube sampling (LHS) in possible parametric ranges are input and calculations of uncertainty propagation through RELAP5/MOD3 code are carried out. Based on the calculations, sensitivity assessment on PRHRS functional criteria and reliability evaluation of the system are presented, which might provide further PSA with PRHR system reliability. (authors)

Evidential analytic hierarchy process dependence assessment methodology in human reliability analysis

International Nuclear Information System (INIS)

Chen, Lu Yuan; Zhou, Xinyi; Xiao, Fuyuan; Deng, Yong; Mahadevan, Sankaran

2017-01-01

In human reliability analysis, dependence assessment is an important issue in risky large complex systems, such as operation of a nuclear power plant. Many existing methods depend on an expert's judgment, which contributes to the subjectivity and restrictions of results. Recently, a computational method, based on the Dempster-Shafer evidence theory and analytic hierarchy process, has been proposed to handle the dependence in human reliability analysis. The model can deal with uncertainty in an analyst's judgment and reduce the subjectivity in the evaluation process. However, the computation is heavy and complicated to some degree. The most important issue is that the existing method is in a positive aspect, which may cause an underestimation of the risk. In this study, a new evidential analytic hierarchy process dependence assessment methodology, based on the improvement of existing methods, has been proposed, which is expected to be easier and more effective

Evidential Analytic Hierarchy Process Dependence Assessment Methodology in Human Reliability Analysis

Directory of Open Access Journals (Sweden)

Luyuan Chen

2017-02-01

Full Text Available In human reliability analysis, dependence assessment is an important issue in risky large complex systems, such as operation of a nuclear power plant. Many existing methods depend on an expert's judgment, which contributes to the subjectivity and restrictions of results. Recently, a computational method, based on the Dempster–Shafer evidence theory and analytic hierarchy process, has been proposed to handle the dependence in human reliability analysis. The model can deal with uncertainty in an analyst's judgment and reduce the subjectivity in the evaluation process. However, the computation is heavy and complicated to some degree. The most important issue is that the existing method is in a positive aspect, which may cause an underestimation of the risk. In this study, a new evidential analytic hierarchy process dependence assessment methodology, based on the improvement of existing methods, has been proposed, which is expected to be easier and more effective.

Evidential analytic hierarchy process dependence assessment methodology in human reliability analysis

Energy Technology Data Exchange (ETDEWEB)

Chen, Lu Yuan; Zhou, Xinyi; Xiao, Fuyuan; Deng, Yong [School of Computer and Information Science, Southwest University, Chongqing (China); Mahadevan, Sankaran [School of Engineering, Vanderbilt University, Nashville (United States)

2017-02-15

In human reliability analysis, dependence assessment is an important issue in risky large complex systems, such as operation of a nuclear power plant. Many existing methods depend on an expert's judgment, which contributes to the subjectivity and restrictions of results. Recently, a computational method, based on the Dempster-Shafer evidence theory and analytic hierarchy process, has been proposed to handle the dependence in human reliability analysis. The model can deal with uncertainty in an analyst's judgment and reduce the subjectivity in the evaluation process. However, the computation is heavy and complicated to some degree. The most important issue is that the existing method is in a positive aspect, which may cause an underestimation of the risk. In this study, a new evidential analytic hierarchy process dependence assessment methodology, based on the improvement of existing methods, has been proposed, which is expected to be easier and more effective.

Current issues and perspectives in food safety and risk assessment.

Science.gov (United States)

Eisenbrand, G

2015-12-01

In this review, current issues and opportunities in food safety assessment are discussed. Food safety is considered an essential element inherent in global food security. Hazard characterization is pivotal within the continuum of risk assessment, but it may be conceived only within a very limited frame as a true alternative to risk assessment. Elucidation of the mode of action underlying a given hazard is vital to create a plausible basis for human toxicology evaluation. Risk assessment, to convey meaningful risk communication, must be based on appropriate and reliable consideration of both exposure and mode of action. New perspectives, provided by monitoring human exogenous and endogenous exposure biomarkers, are considered of great promise to support classical risk extrapolation from animal toxicology. © The Author(s) 2015.

Failure Modes Taxonomy for Reliability Assessment of Digital Instrumentation and Control Systems for Probabilistic Risk Analysis - Failure modes taxonomy for reliability assessment of digital I and C systems for PRA

International Nuclear Information System (INIS)

Amri, A.; Blundell, N.; ); Authen, S.; Betancourt, L.; Coyne, K.; Halverson, D.; Li, M.; Taylor, G.; Bjoerkman, K.; Brinkman, H.; Postma, W.; Bruneliere, H.; Chirila, M.; Gheorge, R.; Chu, L.; Yue, M.; Delache, J.; Georgescu, G.; Deleuze, G.; Quatrain, R.; Thuy, N.; Holmberg, J.-E.; Kim, M.C.; Kondo, K.; Mancini, F.; Piljugin, E.; Stiller, J.; Sedlak, J.; Smidts, C.; Sopira, V.

2015-01-01

Digital protection and control systems appear as upgrades in older nuclear power plants (NPP), and are commonplace in new NPPs. To assess the risk of NPP operation and to determine the risk impact of digital systems, there is a need to quantitatively assess the reliability of the digital systems in a justifiable manner. Due to the many unique attributes of digital systems (e.g., functions are implemented by software, units of the system interact in a communication network, faults can be identified and handled online), a number of modelling and data collection challenges exist, and international consensus on the reliability modelling has not yet been reached. The objective of the task group called DIGREL has been to develop a taxonomy of failure modes of digital components for the purposes of probabilistic risk analysis (PRA). An activity focused on the development of a common taxonomy of failure modes is seen as an important step towards standardised digital instrumentation and control (I and C) reliability assessment techniques for PRA. Needs from PRA has guided the work, meaning, e.g., that the I and C system and its failures are studied from the point of view of their functional significance point of view. The taxonomy will be the basis of future modelling and quantification efforts. It will also help to define a structure for data collection and to review PRA studies. The proposed failure modes taxonomy has been developed by first collecting examples of taxonomies provided by the task group organisations. This material showed some variety in the handling of I and C hardware failure modes, depending on the context where the failure modes have been defined. Regarding the software part of I and C, failure modes defined in NPP PRAs have been simple - typically a software CCF failing identical processing units. The DIGREL task group has defined a new failure modes taxonomy based on a hierarchical definition of five levels of abstraction: 1. system level (complete

Reliability and comparison of acromion assessment techniques on x-ray and magnetic resonance imaging (reliability of acromion assessment techniques)

International Nuclear Information System (INIS)

Viskontas, D.G.; MacDermid, J.C.; Drosdowech, D.S.; Garvin, G.J.; Romano, W.M.; Faber, K.J.

2005-01-01

To determine the reliability and correlation of plain radiography and magnetic resonance imaging (MRI) in the assessment of acromion morphology. Materials and Methods: Acromion morphology was assessed using the lateral acromion angle (LAA) and the acromion-humeral interval (AHI). Thirty patients who had x-rays and MRI for impingement syndrome were included. Six blinded observers assessed the acromion morphology subjectively and objectively. Results: Neither acromion assessment technique demonstrated a positive correlation (kappa and intraclass coefficient 0.55) when measured objectively by experienced observers. Conclusion: The LAA and the AHI are both reliable acromion assessment techniques on X-ray and MRI when measured objectively and by experienced observers. (author)

Risk assessment of complex accident scenarios

International Nuclear Information System (INIS)

Kluegel, Jens-Uwe

2012-01-01

The use of methods of risk assessment in accidents in nuclear plants is based on an old tradition. The first consistent systematic study is considered to be the Rasmussen Study of the U.S. Nuclear Regulatory Commission, NRC, WASH-1400. Above and beyond the realm of nuclear technology, there is an extensive range of accident, risk and reliability research into technical-administrative systems. In the past, it has been this area of research which has led to the development of concepts of safety precautions of the type also introduced into nuclear technology (barrier concept, defense in depth, single-failure criterion), where they are now taken for granted as trivial concepts. Also for risk analysis, nuclear technology made use of methods (such as event and fault tree analyses) whose origins were outside the nuclear field. One area in which the use of traditional methods of probabilistic safety analysis is encountering practical problems is risk assessment of complex accident scenarios in nuclear technology. A definition is offered of the term 'complex accident scenarios' in nuclear technology. A number of problems are addressed which arise in the use of traditional PSA procedures in risk assessment of complex accident scenarios. Cases of complex accident scenarios are presented to demonstrate methods of risk assessment which allow robust results to be obtained even when traditional techniques of risk analysis are maintained as a matter of principle. These methods are based on the use of conditional risk metrics. (orig.)

Interaction of CREDO [Centralized Reliability Data Organization] with the EBR-II [Experimental Breeder Reactor II] PRA [probabilistic risk assessment] development

International Nuclear Information System (INIS)

Smith, M.S.; Ragland, W.A.

1989-01-01

The National Academy of Sciences review of US Department of Energy (DOE) class 1 reactors recommended that the Experimental Breeder Reactor II (EBR-II), operated by Argonne National Laboratory (ANL), develop a level 1 probabilistic risk assessment (PRA) and make provisions for level 2 and level 3 PRAs based on the results of the level 1 PRA. The PRA analysis group at ANL will utilize the Centralized Reliability Data Organization (CREDO) at Oak Ridge National Laboratory to support the PRA data needs. CREDO contains many years of empirical liquid-metal reactor component data from EBR-II. CREDO is a mutual data- and cost-sharing system sponsored by DOE and the Power Reactor and Nuclear Fuels Development Corporation of Japan. CREDO is a component based data system; data are collected on components that are liquid-metal specific, associated with a liquid-metal environment, contained in systems that interface with liquid-metal environments, or are safety related for use in reliability/availability/maintainability (RAM) analyses of advanced reactors. The links between the EBR-II PRA development effort and the CREDO data collection at EBR-II extend beyond the sharing of data. The PRA provides a measure of the relative contribution to risk of the various components. This information can be used to prioritize future CREDO data collection activities at EBR-II and other sites

Reliability assessment using Bayesian networks. Case study on quantative reliability estimation of a software-based motor protection relay

International Nuclear Information System (INIS)

Helminen, A.; Pulkkinen, U.

2003-06-01

In this report a quantitative reliability assessment of motor protection relay SPAM 150 C has been carried out. The assessment focuses to the methodological analysis of the quantitative reliability assessment using the software-based motor protection relay as a case study. The assessment method is based on Bayesian networks and tries to take the full advantage of the previous work done in a project called Programmable Automation System Safety Integrity assessment (PASSI). From the results and experiences achieved during the work it is justified to claim that the assessment method presented in the work enables a flexible use of qualitative and quantitative elements of reliability related evidence in a single reliability assessment. At the same time the assessment method is a concurrent way of reasoning one's beliefs and references about the reliability of the system. Full advantage of the assessment method is taken when using the method as a way to cultivate the information related to the reliability of software-based systems. The method can also be used as a communicational instrument in a licensing process of software-based systems. (orig.)

Measuring time and risk preferences: Reliability, stability, domain specificity

NARCIS (Netherlands)

Wölbert, E.M.; Riedl, A.M.

2013-01-01

To accurately predict behavior economists need reliable measures of individual time preferences and attitudes toward risk and typically need to assume stability of these characteristics over time and across decision domains. We test the reliability of two choice tasks for eliciting discount rates,

Reliability assessment based on subjective inferences

International Nuclear Information System (INIS)

Ma Zhibo; Zhu Jianshi; Xu Naixin

2003-01-01

The reliability information which comes from subjective analysis is often incomplete prior. This information can be generally assumed to exist in the form of either a stated prior mean of R (reliability) or a stated prior credibility interval on R. An efficient approach is developed to determine a complete beta prior distribution from the subjective information according to the principle of maximum entropy, and the the reliability of survival/failure product is assessed via Bayes theorem. Numerical examples are presented to illustrate the methods

Validity and reliability of a questionnaire on knowledge of cardiovascular risk factors for use in Brazil

Directory of Open Access Journals (Sweden)

Marco Aurelio Lumertz Saffi

2013-10-01

Full Text Available Using a sample of patients with coronary artery disease, this methodological study aimed to conduct a cross-cultural adaptation and validation of a questionnaire on knowledge of cardiovascular risk factors (Q-FARCS, lifestyle changes, and treatment adherence for use in Brazil. The questionnaire has three scales: general knowledge of risk factors (RFs; specific knowledge of these RFs; and lifestyle changes achieved. Cross-cultural adaptation included translation, synthesis, back-translation, expert committee review, and pretesting. Face and content validity, reliability, and construct validity were measured. Cronbach’s alpha for the total sample (n = 240 was 0.75. Assessment of psychometric properties revealed adequate face and content validity, and the construct revealed seven components. It was concluded that the Brazilian version of Q-FARCS had adequate reliability and validity for the assessment of knowledge of cardiovascular RFs.

Risk assessments for dating violence in mid to late adolescence and early adulthood.

Science.gov (United States)

Tapp, James; Moore, Estelle

2016-10-01

The objective of this paper is to review risk instruments that have been used in the assessment of the potential for violence within the dating relationships of young people. A review of the dating violence literature was conducted to identify risk assessment approaches that have been used to predict harmful behaviour within the dating relationships of people aged between 15 and 30 years. Risk assessments were evaluated on recommended quality criteria: predictive validity, accuracy (sensitivity and specificity) and inter-rater reliability. Only five studies describing assessments that focused specifically on dating violence risk factors were selected for review. Three assessments encompassed dating behaviours by victims that have been associated with an increased risk of further victimisation. Drawing on this evidence, we conclude that young people appear to be at greater risk of encountering dating violence if they have experienced violence in earlier attachment relationships; if their skills for coping with conflict and responding to coercion are limited and if the presence of peer influences reinforces offence supportive attitudes. The reliability and validity of existing intimate partner violence risk assessments that conceptually overlap with elements of dating violence risk warrant investigation to inform risk assessment developments in this field and, building on this, possible interventions to minimise future harm. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

Systems reliability analyses and risk analyses for the licencing procedure under atomic law

International Nuclear Information System (INIS)

Berning, A.; Spindler, H.

1983-01-01

For the licencing procedure under atomic law in accordance with Article 7 AtG, the nuclear power plant as a whole needs to be assessed, plus the reliability of systems and plant components that are essential to safety are to be determined with probabilistic methods. This requirement is the consequence of safety criteria for nuclear power plants issued by the Home Department (BMI). Systems reliability studies and risk analyses used in licencing procedures under atomic law are identified. The stress is on licencing decisions, mainly for PWR-type reactors. Reactor Safety Commission (RSK) guidelines, examples of reasoning in legal proceedings and arguments put forth by objectors are also dealt with. Correlations are shown between reliability analyses made by experts and licencing decisions by means of examples. (orig./HP) [de

Reliability Assessment of Concrete Bridges

DEFF Research Database (Denmark)

Thoft-Christensen, Palle; Middleton, C. R.

This paper is partly based on research performed for the Highways Agency, London, UK under the project DPU/9/44 "Revision of Bridge Assessment Rules Based on Whole Life Performance: concrete bridges". It contains the details of a methodology which can be used to generate Whole Life (WL) reliability...... profiles. These WL reliability profiles may be used to establish revised rules for concrete bridges. This paper is to some extend based on Thoft-Christensen et. al. [1996], Thoft-Christensen [1996] et. al. and Thoft-Christensen [1996]....

Automated reliability assessment for spectroscopic redshift measurements

Science.gov (United States)

Jamal, S.; Le Brun, V.; Le Fèvre, O.; Vibert, D.; Schmitt, A.; Surace, C.; Copin, Y.; Garilli, B.; Moresco, M.; Pozzetti, L.

2018-03-01

Context. Future large-scale surveys, such as the ESA Euclid mission, will produce a large set of galaxy redshifts (≥106) that will require fully automated data-processing pipelines to analyze the data, extract crucial information and ensure that all requirements are met. A fundamental element in these pipelines is to associate to each galaxy redshift measurement a quality, or reliability, estimate. Aim. In this work, we introduce a new approach to automate the spectroscopic redshift reliability assessment based on machine learning (ML) and characteristics of the redshift probability density function. Methods: We propose to rephrase the spectroscopic redshift estimation into a Bayesian framework, in order to incorporate all sources of information and uncertainties related to the redshift estimation process and produce a redshift posterior probability density function (PDF). To automate the assessment of a reliability flag, we exploit key features in the redshift posterior PDF and machine learning algorithms. Results: As a working example, public data from the VIMOS VLT Deep Survey is exploited to present and test this new methodology. We first tried to reproduce the existing reliability flags using supervised classification in order to describe different types of redshift PDFs, but due to the subjective definition of these flags (classification accuracy 58%), we soon opted for a new homogeneous partitioning of the data into distinct clusters via unsupervised classification. After assessing the accuracy of the new clusters via resubstitution and test predictions (classification accuracy 98%), we projected unlabeled data from preliminary mock simulations for the Euclid space mission into this mapping to predict their redshift reliability labels. Conclusions: Through the development of a methodology in which a system can build its own experience to assess the quality of a parameter, we are able to set a preliminary basis of an automated reliability assessment for

Different Reliability Assessment Approaches for Wave Energy Converters

DEFF Research Database (Denmark)

Ambühl, Simon; Kramer, Morten Mejlhede; Sørensen, John Dalsgaard

2015-01-01

Reliability assessments are of importance for wave energy converters (WECs) due to the fact that accessibility might be limited in case of failure and maintenance. These failure rates can be adapted by reliability considerations. There are two different approaches to how reliability can...

A clinical assessment tool used for physiotherapy students--is it reliable?

Science.gov (United States)

Lewis, Lucy K; Stiller, Kathy; Hardy, Frances

2008-01-01

Educational institutions providing professional programs such as physiotherapy must provide high-quality student assessment procedures. To ensure that assessment is consistent, assessment tools should have an acceptable level of reliability. There is a paucity of research evaluating the reliability of clinical assessment tools used for physiotherapy students. This study evaluated the inter- and intrarater reliability of an assessment tool used for physiotherapy students during a clinical placement. Five clinical educators and one academic participated in the study. Each rater independently marked 22 student written assessments that had been completed by students after viewing a videotaped patient physiotherapy assessment. The raters repeated the marking process 7 weeks later, with the assessments provided in a randomised order. The interrater reliability (Intraclass Correlation Coefficient) for the total scores was 0.32, representing a poor level of reliability. A high level of intrarater reliability (percentage agreement) was found for the clinical educators, with a difference in section scores of one mark or less on 93.4% of occasions. Further research should be undertaken to reevaluate the reliability of this clinical assessment tool following training. The reliability of clinical assessment tools used in other areas of physiotherapy education should be formally measured rather than assumed.

An approach for assessing human decision reliability

International Nuclear Information System (INIS)

Pyy, P.

2000-01-01

This paper presents a method to study human reliability in decision situations related to nuclear power plant disturbances. Decisions often play a significant role in handling of emergency situations. The method may be applied to probabilistic safety assessments (PSAs) in cases where decision making is an important dimension of an accident sequence. Such situations are frequent e.g. in accident management. In this paper, a modelling approach for decision reliability studies is first proposed. Then, a case study with two decision situations with relatively different characteristics is presented. Qualitative and quantitative findings of the study are discussed. In very simple decision cases with time pressure, time reliability correlation proved out to be a feasible reliability modelling method. In all other decision situations, more advanced probabilistic decision models have to be used. Finally, decision probability assessment by using simulator run results and expert judgement is presented

Generation reliability assessment in oligopoly power market using Monte Carlo simulation

International Nuclear Information System (INIS)

Haroonabadi, H.; Haghifam, M.R.

2007-01-01

This paper addressed issues regarding power generation reliability assessment (HLI) in deregulated power pool markets. Most HLI reliability evaluation methods are based on the loss of load (LOLE) approach which is among the most suitable indices to describe the level of generation reliability. LOLE refers to the time in which load is greater than the amount of available generation. While most reliability assessments deal only with power system constraints, this study considered HLI reliability assessment in an oligopoly power market using Monte Carlo simulation (MCS). It evaluated the sensitivity of the reliability index to different reserve margins and future margins. The reliability index was determined by intersecting the offer and demand curves of power plants and comparing them to other parameters. The paper described the fundamentals of an oligopoly power pool market and proposed an algorithm for HLI reliability assessment for such a market. The proposed method was assessed on the IEEE-Reliability Test System with satisfactory results. In all cases, generation reliability indices were evaluated with different reserve margins and various load levels. 19 refs., 7 figs., 1 appendix

Challenges in Risk Assessment: Quantitative Risk Assessment

OpenAIRE

Jacxsens, Liesbeth; Uyttendaele, Mieke; De Meulenaer, Bruno

2016-01-01

The process of risk analysis consists out of three components, risk assessment, risk management and risk communication. These components are internationally well spread by Codex Alimentarius Commission as being the basis for setting science based standards, criteria on food safety hazards, e.g. setting maximum limits of mycotoxins in foodstuffs. However, the technical component risk assessment is hard to elaborate and to understand. Key in a risk assessment is the translation of biological or...

A comparative evaluation of five human reliability assessment techniques

International Nuclear Information System (INIS)

Kirwan, B.

1988-01-01

A field experiment was undertaken to evaluate the accuracy, usefulness, and resources requirements of five human reliability quantification techniques (Techniques for Human Error Rate Prediction (THERP); Paired Comparisons, Human Error Assessment and Reduction Technique (HEART), Success Liklihood Index Method (SLIM)-Multi Attribute Utility Decomposition (MAUD), and Absolute Probability Judgement). This was achieved by assessing technique predictions against a set of known human error probabilities, and by comparing their predictions on a set of five realistic Probabilisitc Risk Assessment (PRA) human error. On a combined measure of accuracy THERP and Absolute Probability Judgement performed best, whilst HEART showed indications of accuracy and was lower in resources usage than other techniques. HEART and THERP both appear to benefit from using trained assessors in order to obtain the best results. SLIM and Paired Comparisons require further research on achieving a robust calibration relationship between their scale values and absolute probabilities. (author)

Review on pen-and-paper-based observational methods for assessing ergonomic risk factors of computer work.

Science.gov (United States)

Rahman, Mohd Nasrull Abdol; Mohamad, Siti Shafika

2017-01-01

Computer works are associated with Musculoskeletal Disorders (MSDs). There are several methods have been developed to assess computer work risk factor related to MSDs. This review aims to give an overview of current techniques available for pen-and-paper-based observational methods in assessing ergonomic risk factors of computer work. We searched an electronic database for materials from 1992 until 2015. The selected methods were focused on computer work, pen-and-paper observational methods, office risk factors and musculoskeletal disorders. This review was developed to assess the risk factors, reliability and validity of pen-and-paper observational method associated with computer work. Two evaluators independently carried out this review. Seven observational methods used to assess exposure to office risk factor for work-related musculoskeletal disorders were identified. The risk factors involved in current techniques of pen and paper based observational tools were postures, office components, force and repetition. From the seven methods, only five methods had been tested for reliability. They were proven to be reliable and were rated as moderate to good. For the validity testing, from seven methods only four methods were tested and the results are moderate. Many observational tools already exist, but no single tool appears to cover all of the risk factors including working posture, office component, force, repetition and office environment at office workstations and computer work. Although the most important factor in developing tool is proper validation of exposure assessment techniques, the existing observational method did not test reliability and validity. Futhermore, this review could provide the researchers with ways on how to improve the pen-and-paper-based observational method for assessing ergonomic risk factors of computer work.

Analysis and assessment of water treatment plant reliability

Directory of Open Access Journals (Sweden)

Szpak Dawid

2017-03-01

Full Text Available The subject of the publication is the analysis and assessment of the reliability of the surface water treatment plant (WTP. In the study the one parameter method of reliability assessment was used. Based on the flow sheet derived from the water company the reliability scheme of the analysed WTP was prepared. On the basis of the daily WTP work report the availability index Kg for the individual elements included in the WTP, was determined. Then, based on the developed reliability scheme showing the interrelationships between elements, the availability index Kg for the whole WTP was determined. The obtained value of the availability index Kg was compared with the criteria values.

Probabilistic Risk Assessment (PRA): A Practical and Cost Effective Approach

Science.gov (United States)

Lee, Lydia L.; Ingegneri, Antonino J.; Djam, Melody

2006-01-01

The Lunar Reconnaissance Orbiter (LRO) is the first mission of the Robotic Lunar Exploration Program (RLEP), a space exploration venture to the Moon, Mars and beyond. The LRO mission includes spacecraft developed by NASA Goddard Space Flight Center (GSFC) and seven instruments built by GSFC, Russia, and contractors across the nation. LRO is defined as a measurement mission, not a science mission. It emphasizes the overall objectives of obtaining data to facilitate returning mankind safely to the Moon in preparation for an eventual manned mission to Mars. As the first mission in response to the President's commitment of the journey of exploring the solar system and beyond: returning to the Moon in the next decade, then venturing further into the solar system, ultimately sending humans to Mars and beyond, LRO has high-visibility to the public but limited resources and a tight schedule. This paper demonstrates how NASA's Lunar Reconnaissance Orbiter Mission project office incorporated reliability analyses in assessing risks and performing design tradeoffs to ensure mission success. Risk assessment is performed using NASA Procedural Requirements (NPR) 8705.5 - Probabilistic Risk Assessment (PRA) Procedures for NASA Programs and Projects to formulate probabilistic risk assessment (PRA). As required, a limited scope PRA is being performed for the LRO project. The PRA is used to optimize the mission design within mandated budget, manpower, and schedule constraints. The technique that LRO project office uses to perform PRA relies on the application of a component failure database to quantify the potential mission success risks. To ensure mission success in an efficient manner, low cost and tight schedule, the traditional reliability analyses, such as reliability predictions, Failure Modes and Effects Analysis (FMEA), and Fault Tree Analysis (FTA), are used to perform PRA for the large system of LRO with more than 14,000 piece parts and over 120 purchased or contractor

[Reliability theory based on quality risk network analysis for Chinese medicine injection].

Science.gov (United States)

Li, Zheng; Kang, Li-Yuan; Fan, Xiao-Hui

2014-08-01

A new risk analysis method based upon reliability theory was introduced in this paper for the quality risk management of Chinese medicine injection manufacturing plants. The risk events including both cause and effect ones were derived in the framework as nodes with a Bayesian network analysis approach. It thus transforms the risk analysis results from failure mode and effect analysis (FMEA) into a Bayesian network platform. With its structure and parameters determined, the network can be used to evaluate the system reliability quantitatively with probabilistic analytical appraoches. Using network analysis tools such as GeNie and AgenaRisk, we are able to find the nodes that are most critical to influence the system reliability. The importance of each node to the system can be quantitatively evaluated by calculating the effect of the node on the overall risk, and minimization plan can be determined accordingly to reduce their influences and improve the system reliability. Using the Shengmai injection manufacturing plant of SZYY Ltd as a user case, we analyzed the quality risk with both static FMEA analysis and dynamic Bayesian Network analysis. The potential risk factors for the quality of Shengmai injection manufacturing were identified with the network analysis platform. Quality assurance actions were further defined to reduce the risk and improve the product quality.

Plant and control system reliability and risk model

International Nuclear Information System (INIS)

Niemelae, I.M.

1986-01-01

A new reliability modelling technique for control systems and plants is demonstrated. It is based on modified boolean algebra and it has been automated into an efficient computer code called RELVEC. The code is useful for getting an overall view of the reliability parameters or for an in-depth reliability analysis, which is essential in risk analysis, where the model must be capable of answering to specific questions like: 'What is the probability of this temperature limiter to provide a false alarm', or 'what is the probability of air pressure in this subsystem to drop below lower limit'. (orig./DG)

Human reliability analysis

International Nuclear Information System (INIS)

Dougherty, E.M.; Fragola, J.R.

1988-01-01

The authors present a treatment of human reliability analysis incorporating an introduction to probabilistic risk assessment for nuclear power generating stations. They treat the subject according to the framework established for general systems theory. Draws upon reliability analysis, psychology, human factors engineering, and statistics, integrating elements of these fields within a systems framework. Provides a history of human reliability analysis, and includes examples of the application of the systems approach

Engineering Risk Assessment of Space Thruster Challenge Problem

Science.gov (United States)

Mathias, Donovan L.; Mattenberger, Christopher J.; Go, Susie

2014-01-01

The Engineering Risk Assessment (ERA) team at NASA Ames Research Center utilizes dynamic models with linked physics-of-failure analyses to produce quantitative risk assessments of space exploration missions. This paper applies the ERA approach to the baseline and extended versions of the PSAM Space Thruster Challenge Problem, which investigates mission risk for a deep space ion propulsion system with time-varying thruster requirements and operations schedules. The dynamic mission is modeled using a combination of discrete and continuous-time reliability elements within the commercially available GoldSim software. Loss-of-mission (LOM) probability results are generated via Monte Carlo sampling performed by the integrated model. Model convergence studies are presented to illustrate the sensitivity of integrated LOM results to the number of Monte Carlo trials. A deterministic risk model was also built for the three baseline and extended missions using the Ames Reliability Tool (ART), and results are compared to the simulation results to evaluate the relative importance of mission dynamics. The ART model did a reasonable job of matching the simulation models for the baseline case, while a hybrid approach using offline dynamic models was required for the extended missions. This study highlighted that state-of-the-art techniques can adequately adapt to a range of dynamic problems.

New approaches for improving cardiovascular risk assessment.

Science.gov (United States)

Paredes, Simão; Rocha, Teresa; Mendes, Diana; Carvalho, Paulo; Henriques, Jorge; Morais, João; Ferreira, Jorge; Mendes, Miguel

2016-01-01

Clinical guidelines recommend the use of cardiovascular risk assessment tools (risk scores) to predict the risk of events such as cardiovascular death, since these scores can aid clinical decision-making and thereby reduce the social and economic costs of cardiovascular disease (CVD). However, despite their importance, risk scores present important weaknesses that can diminish their reliability in clinical contexts. This study presents a new framework, based on current risk assessment tools, that aims to minimize these limitations. Appropriate application and combination of existing knowledge is the main focus of this work. Two different methodologies are applied: (i) a combination scheme that enables data to be extracted and processed from various sources of information, including current risk assessment tools and the contributions of the physician; and (ii) a personalization scheme based on the creation of patient groups with the purpose of identifying the most suitable risk assessment tool to assess the risk of a specific patient. Validation was performed based on a real patient dataset of 460 patients at Santa Cruz Hospital, Lisbon, Portugal, diagnosed with non-ST-segment elevation acute coronary syndrome. Promising results were obtained with both approaches, which achieved sensitivity, specificity and geometric mean of 78.79%, 73.07% and 75.87%, and 75.69%, 69.79% and 72.71%, respectively. The proposed approaches present better performances than current CVD risk scores; however, additional datasets are required to back up these findings. Copyright © 2015 Sociedade Portuguesa de Cardiologia. Published by Elsevier España. All rights reserved.

A method to assign failure rates for piping reliability assessments

International Nuclear Information System (INIS)

Gamble, R.M.; Tagart, S.W. Jr.

1991-01-01

This paper reports on a simplified method that has been developed to assign failure rates that can be used in reliability and risk studies of piping. The method can be applied on a line-by-line basis by identifying line and location specific attributes that can lead to piping unreliability from in-service degradation mechanisms and random events. A survey of service experience for nuclear piping reliability also was performed. The data from this survey provides a basis for identifying in-service failure attributes and assigning failure rates for risk and reliability studies

Reliability Assessment and Reliability-Based Inspection and Maintenance of Offshore Wind Turbines

DEFF Research Database (Denmark)

Ramírez, José G. Rangel; Sørensen, John Dalsgaard

2009-01-01

Probabilistic methodologies represent an important tool to identify the suitable strategy to inspect and deal with the deterioration in structures such as offshore wind turbines (OWT). Reliability based methods such as Risk Based Inspection (RBI) planning may represent a proper methodology to opt...

Reliability and Probabilistic Risk Assessment - How They Play Together

Science.gov (United States)

Safie, Fayssal M.; Stutts, Richard; Huang, Zhaofeng

2015-01-01

The objective of this presentation is to discuss the PRA process and the reliability engineering discipline, their differences and similarities, and how they are used as complimentary analyses to support design and flight decisions.

A perspective of PC-based probabilistic risk assessment

International Nuclear Information System (INIS)

Sattison, M.B.; Rasmuson, D.M.; Robinson, R.C.; Russell, K.D.; Van Siclen, V.S.

1987-01-01

Probabilistic risk assessment (PRA) information has been under-utilized in the past due to the large effort required to input the PRA data and the large expense of the computers needed to run PRA codes. The microcomputer-based Integrated Reliability and Risk Analysis System (IRRAS) and the System Analysis and Risk Assessment (SARA) System, under development at the Idaho National Engineering Laboratory, have greatly enhanced the ability of managers to use PRA techniques in their decision-making. IRRAS is a tool that allows an analyst to create, modify, update, and reanalyze a plant PRA to keep the risk assessment current with the plant's configuration and operation. The SARA system is used to perform sensitivity studies on the results of a PRA. This type of analysis can be used to evaluate proposed changes to a plant or its operation. The success of these two software projects demonstrate that risk information can be made readily available to those that need it. This is the first step in the development of a true risk management capability

Health effects of low-level ionising radiation: biological basis for risk assessment

International Nuclear Information System (INIS)

Upton, A.C.

1987-01-01

The biological basis for risk assessment is discussed. The risks of carcinogenic effects, teratogenic effects, and genetic (heritable) effects are estimated to vary in proportion with the dose of radiation in the low-dose domain; however, the risks also appear to vary with the LET of the radiation, age at the time of irradiation, and other variables. Although the data suffice to place the risks in perspective with other hazards of modern life, further research to refine the reliability of the risk assessment is called for. (author)

A reliability assessment methodology for the VHTR passive safety system

International Nuclear Information System (INIS)

Lee, Hyungsuk; Jae, Moosung

2014-01-01

The passive safety system of a VHTR (Very High Temperature Reactor), which has recently attracted worldwide attention, is currently being considered for the design of safety improvements for the next generation of nuclear power plants in Korea. The functionality of the passive system does not rely on an external source of an electrical support system, but on the intelligent use of natural phenomena. Its function involves an ultimate heat sink for a passive secondary auxiliary cooling system, especially during a station blackout such as the case of the Fukushima Daiichi reactor accidents. However, it is not easy to quantitatively evaluate the reliability of passive safety for the purpose of risk analysis, considering the existing active system failure since the classical reliability assessment method cannot be applied. Therefore, we present a new methodology to quantify the reliability based on reliability physics models. This evaluation framework is then applied to of the conceptually designed VHTR in Korea. The Response Surface Method (RSM) is also utilized for evaluating the uncertainty of the maximum temperature of nuclear fuel. The proposed method could contribute to evaluating accident sequence frequency and designing new innovative nuclear systems, such as the reactor cavity cooling system (RCCS) in VHTR to be designed and constructed in Korea.

Uncertainty characterization approaches for risk assessment of DBPs in drinking water: a review.

Science.gov (United States)

Chowdhury, Shakhawat; Champagne, Pascale; McLellan, P James

2009-04-01

The management of risk from disinfection by-products (DBPs) in drinking water has become a critical issue over the last three decades. The areas of concern for risk management studies include (i) human health risk from DBPs, (ii) disinfection performance, (iii) technical feasibility (maintenance, management and operation) of treatment and disinfection approaches, and (iv) cost. Human health risk assessment is typically considered to be the most important phase of the risk-based decision-making or risk management studies. The factors associated with health risk assessment and other attributes are generally prone to considerable uncertainty. Probabilistic and non-probabilistic approaches have both been employed to characterize uncertainties associated with risk assessment. The probabilistic approaches include sampling-based methods (typically Monte Carlo simulation and stratified sampling) and asymptotic (approximate) reliability analysis (first- and second-order reliability methods). Non-probabilistic approaches include interval analysis, fuzzy set theory and possibility theory. However, it is generally accepted that no single method is suitable for the entire spectrum of problems encountered in uncertainty analyses for risk assessment. Each method has its own set of advantages and limitations. In this paper, the feasibility and limitations of different uncertainty analysis approaches are outlined for risk management studies of drinking water supply systems. The findings assist in the selection of suitable approaches for uncertainty analysis in risk management studies associated with DBPs and human health risk.

Reliability assessment of Wind turbines

DEFF Research Database (Denmark)

Sørensen, John Dalsgaard

2015-01-01

Wind turbines can be considered as structures that are in between civil engineering structures and machines since they consist of structural components and many electrical and machine components together with a control system. Further, a wind turbine is not a one-of-a-kind structure...... but manufactured in series production based on many component tests, some prototype tests and zeroseries wind turbines. These characteristics influence the reliability assessment where focus in this paper is on the structural components. Levelized Cost Of Energy is very important for wind energy, especially when...... comparing to other energy sources. Therefore much focus is on cost reductions and improved reliability both for offshore and onshore wind turbines. The wind turbine components should be designed to have sufficient reliability level with respect to both extreme and fatigue loads but also not be too costly...

Inter-rater reliability of PATH observations for assessment of ergonomic risk factors in hospital work.

Science.gov (United States)

Park, Jung-Keun; Boyer, Jon; Tessler, Jamie; Casey, Jeffrey; Schemm, Linda; Gore, Rebecca; Punnett, Laura

2009-07-01

This study examined the inter-rater reliability of expert observations of ergonomic risk factors by four analysts. Ten jobs were observed at a hospital using a newly expanded version of the PATH method (Buchholz et al. 1996), to which selected upper extremity exposures had been added. Two of the four raters simultaneously observed each worker onsite for a total of 443 observation pairs containing 18 categorical exposure items each. For most exposure items, kappa coefficients were 0.4 or higher. For some items, agreement was higher both for the jobs with less rapid hand activity and for the analysts with a higher level of ergonomic job analysis experience. These upper extremity exposures could be characterised reliably with real-time observation, given adequate experience and training of the observers. The revised version of PATH is applicable to the analysis of jobs where upper extremity musculoskeletal strain is of concern.

Assessment of Technogenic Accident Risk of Industrial Building Structures

Science.gov (United States)

Baiburin, D. A.; Baiburin, A. Kh

2017-11-01

A methodology for assessing the risk of an industrial building accident was developed taking into account the damage caused by various localization of collapse. Before the beginning of the survey of a facility technical condition, groups including the same type of building structures are selected. Further, assessment is made for the reduction in their load-carrying capacity from the strength and stability conditions taking into account defects. The characteristics of the influence of defects and structural damage on a building safety is the degree of compliance with the standards expressed by the reliability level. Reliability levels assignment is carried out on the basis of calculations, operating experience and inspection of a particular type of structure according to the formalized rules. The risk of collapse according to a separate scenario is calculated for structures that are capable and incapable of causing a progressive ossification. The results of the technique application are based on the analysis of the accident risk at the welding shop “Vysota (Height) 239” of the Chelyabinsk Pipe Rolling Plant.

Risk assessment in the European Community (EC); perspective as partial contributor in decision making

International Nuclear Information System (INIS)

Vinck, W.

1981-01-01

This paper is oriented towards the use of nuclear power for electricity production. The subject is discussed under the following headings: preamble; survey of practice and trends in reliability analyses and risk assessment:general (the risk concept; the types of reliability and risk analysis; the present state and trends of a probabilistic approach in safety analysis); risk analysis, partial contributor in the acceptability-problem (the political scene; technological society; cost effectiveness of risk reduction, cost-risk-benefit balancing; risk perception and acceptance; comparison of energy systems); need for and limitations of quantified safety objectives. (U.K.)

An approach for assessing ALWR passive safety system reliability

International Nuclear Information System (INIS)

Hake, T.M.

1991-01-01

Many advanced light water reactor designs incorporate passive rather than active safety features for front-line accident response. A method for evaluating the reliability of these passive systems in the context of probabilistic risk assessment has been developed at Sandia National Laboratories. This method addresses both the component (e.g. valve) failure aspect of passive system failure, and uncertainties in system success criteria arising from uncertainties in the system's underlying physical processes. These processes provide the system's driving force; examples are natural circulation and gravity-induced injection. This paper describes the method, and provides some preliminary results of application of the approach to the Westinghouse AP600 design

Assessment of the reliability of ultrasonic inspection methods

International Nuclear Information System (INIS)

Haines, N.F.; Langston, D.B.; Green, A.J.; Wilson, R.

1982-01-01

The reliability of NDT techniques has remained an open question for many years. A reliable technique may be defined as one that, when rigorously applied by a number of inspection teams, consistently finds then correctly sizes all defects of concern. In this paper we report an assessment of the reliability of defect detection by manual ultrasonic methods applied to the inspection of thick section pressure vessel weldments. Initially we consider the available data relating to the inherent physical capabilities of ultrasonic techniques to detect cracks in weldment and then, independently, we assess the likely variability in team to team performance when several teams are asked to follow the same specified test procedure. The two aspects of 'capability' and 'variability' are brought together to provide quantitative estimates of the overall reliability of ultrasonic inspection of thick section pressure vessel weldments based on currently existing data. The final section of the paper considers current research programmes on reliability and presents a view on how these will help to further improve NDT reliability. (author)

Historical relationship between performance assessment for radioactive waste disposal and other types of risk assessment

International Nuclear Information System (INIS)

Rechard, R.P.

1999-01-01

This article describes the evolution of the process for assessing the hazards of a geologic disposal system for radioactive waste and, similarly, nuclear power reactors, and the relationship of this process with other assessments of risk, particularly assessments of hazards from manufactured carcinogenic chemicals during use and disposal. This perspective reviews the common history of scientific concepts for risk assessment developed until the 1950s. Computational tools and techniques developed in the late 1950s and early 1960s to analyze the reliability of nuclear weapon delivery systems were adopted in the early 1970s for probabilistic risk assessment of nuclear power reactors, a technology for which behavior was unknown. In turn, these analyses became an important foundation for performance assessment of nuclear waste disposal in the late 1970s. The evaluation of risk to human health and the environment from chemical hazards is built on methods for assessing the dose response of radionuclides in the 1950s. Despite a shared background, however, societal events, often in the form of legislation, have affected the development path for risk assessment for human health, producing dissimilarities between these risk assessments and those for nuclear facilities. An important difference is the regulator's interest in accounting for uncertainty

A study on a reliability assessment methodology for the VHTR safety systems

International Nuclear Information System (INIS)

Lee, Hyung Sok

2012-02-01

The passive safety system of a 300MWt VHTR (Very High Temperature Reactor)which has attracted worldwide attention recently is actively considered for designing the improvement in the safety of the next generation nuclear power plant. The passive system functionality does not rely on an external source of the electrical support system,but on an intelligent use of the natural phenomena, such as convection, conduction, radiation, and gravity. It is not easy to evaluate quantitatively the reliability of the passive safety for the risk analysis considering the existing active system failure since the classical reliability assessment method could not be applicable. Therefore a new reliability methodology needs to be developed and applied for evaluating the reliability of the conceptual designed VHTR in this study. The preliminary evaluation and conceptualization are performed using the concept of the load and capacity theory related to the reliability physics model. The method of response surface method (RSM) is also utilized for evaluating the maximum temperature of nuclear fuel in this study. The significant variables and their correlation are considered for utilizing the GAMMA+ code. The proposed method might contribute to designing the new passive system of the VHTR

Proceedings of the SRESA national conference on reliability and safety engineering

International Nuclear Information System (INIS)

Varde, P.V.; Vaishnavi, P.; Sujatha, S.; Valarmathi, A.

2014-01-01

The objective of this conference was to provide a forum for technical discussions on recent developments in the area of risk based approach and Prognostic Health Management of critical systems in decision making. The reliability and safety engineering methods are concerned with the way which the product fails, and the effects of failure is to understand how a product works and assures acceptable levels of safety. The reliability engineering addresses all the anticipated and possibly unanticipated causes of failure to ensure the occurrence of failure is prevented or minimized. The topics discussed in the conference were: Reliability in Engineering Design, Safety Assessment and Management, Reliability analysis and Assessment , Stochastic Petri nets for reliability Modeling, Dynamic Reliability, Reliability Prediction, Hardware Reliability, Software Reliability in Safety Critical Issues, Probabilistic Safety Assessment, Risk Informed Approach, Dynamic Models for Reliability Analysis, Reliability based Design and Analysis, Prognostics and Health Management, Remaining Useful Life (RUL), Human Reliability Modeling, Risk Based Applications, Hazard and Operability Study (HAZOP), Reliability in Network Security and Quality Assurance and Management etc. The papers relevant to INIS are indexed separately

Risk assessment in man and mouse.

Science.gov (United States)

Balci, Fuat; Freestone, David; Gallistel, Charles R

2009-02-17

Human and mouse subjects tried to anticipate at which of 2 locations a reward would appear. On a randomly scheduled fraction of the trials, it appeared with a short latency at one location; on the complementary fraction, it appeared after a longer latency at the other location. Subjects of both species accurately assessed the exogenous uncertainty (the probability of a short versus a long trial) and the endogenous uncertainty (from the scalar variability in their estimates of an elapsed duration) to compute the optimal target latency for a switch from the short- to the long-latency location. The optimal latency was arrived at so rapidly that there was no reliably discernible improvement over trials. Under these nonverbal conditions, humans and mice accurately assess risks and behave nearly optimally. That this capacity is well-developed in the mouse opens up the possibility of a genetic approach to the neurobiological mechanisms underlying risk assessment.

Adaptation, translation and reliability of the Australian 'Juniors Enjoying Cricket Safely' injury risk perception questionnaire for Sri Lanka.

Science.gov (United States)

Gamage, Prasanna J; Fortington, Lauren V; Finch, Caroline F

2018-01-01

Cricket is a very popular sport in Sri Lanka. In this setting there has been limited research; specifically, there is little knowledge of cricket injuries. To support future research possibilities, the aim of this study was to cross-culturally adapt, translate and test the reliability of an Australian-developed questionnaire for the Sri Lankan context. The Australian 'Juniors Enjoying Cricket Safely' (JECS-Aus) injury risk perception questionnaire was cross-culturally adapted to suit the Sri Lankan context and subsequently translated into the two main languages (Sinhala and Tamil) based on standard forward-back translation. The translated questionnaires were examined for content validity by two language schoolteachers. The questionnaires were completed twice, 2 weeks apart, by two groups of school cricketers (males) aged 11-15 years (Sinhala (n=24), Tamil (n=30)) to assess reliability. Test-retest scores were evaluated for agreement. Where responses were statistics were calculated. Questions with moderate-to-poor test-retest reliability (κAus questionnaire for use in a different population, providing an outcome measure for assessing injury risk perceptions in Sri Lankan junior cricketers.

Quantitative reliability assessment for safety critical system software

International Nuclear Information System (INIS)

Chung, Dae Won; Kwon, Soon Man

2005-01-01

An essential issue in the replacement of the old analogue I and C to computer-based digital systems in nuclear power plants is the quantitative software reliability assessment. Software reliability models have been successfully applied to many industrial applications, but have the unfortunate drawback of requiring data from which one can formulate a model. Software which is developed for safety critical applications is frequently unable to produce such data for at least two reasons. First, the software is frequently one-of-a-kind, and second, it rarely fails. Safety critical software is normally expected to pass every unit test producing precious little failure data. The basic premise of the rare events approach is that well-tested software does not fail under normal routine and input signals, which means that failures must be triggered by unusual input data and computer states. The failure data found under the reasonable testing cases and testing time for these conditions should be considered for the quantitative reliability assessment. We will present the quantitative reliability assessment methodology of safety critical software for rare failure cases in this paper

Online application of a risk management system for risk assessment and monitoring at NPPs

Energy Technology Data Exchange (ETDEWEB)

Yang, Jun, E-mail: youngjun51@hotmail.com [Key Laboratory of Fundamental Science on Nuclear Safety and Simulation Technology, Harbin Engineering University (China); Yang, Ming, E-mail: yangming@hrbeu.edu.cn [Key Laboratory of Fundamental Science on Nuclear Safety and Simulation Technology, Harbin Engineering University (China); Wang, Wenlin, E-mail: wlwang0618@126.com [Key Laboratory of Fundamental Science on Nuclear Safety and Simulation Technology, Harbin Engineering University (China); Li, Fengjun, E-mail: leefengjun@163.com [China Nuclear Power Engineering Co. Ltd (China)

2016-08-15

Highlights: • A generic GO-FLOW modeling structure is proposed for easily Living PSA development and analysis. • Hierarchical and modularized scheme is applied in the development of Living PSA models and database. • A risk management system is developed by GO-FLOW method. • Functional testing is conducted on the risk management system for performance evaluation. • The fast solution time derived from Living PSA application is supportive in plant safety management. - Abstract: The paper presents a risk management system on the basis of Living PSA models which are developed under a proposed generic GO-FLOW modeling method with a hierarchical and modular structure. The design of the risk management system is aiming at assisting plant personnel to manage maintenance plan and system configuration, and conduct system reliability monitoring, risk monitoring and risk management quickly and conveniently through graphical user interfaces without going deep into the details of building, updating and analyzing reliability and risk models. The performance of the proposed risk management system was tested on a full-scale simulator of PWR nuclear power plant and demonstrated that the fast solution time derived from utilization of hierarchical and modularized Living PSA models is strongly supportive for instantaneous risk assessment as well as for daily risk management at NPPs.

Cut set-based risk and reliability analysis for arbitrarily interconnected networks

Science.gov (United States)

Wyss, Gregory D.

2000-01-01

Method for computing all-terminal reliability for arbitrarily interconnected networks such as the United States public switched telephone network. The method includes an efficient search algorithm to generate minimal cut sets for nonhierarchical networks directly from the network connectivity diagram. Efficiency of the search algorithm stems in part from its basis on only link failures. The method also includes a novel quantification scheme that likewise reduces computational effort associated with assessing network reliability based on traditional risk importance measures. Vast reductions in computational effort are realized since combinatorial expansion and subsequent Boolean reduction steps are eliminated through analysis of network segmentations using a technique of assuming node failures to occur on only one side of a break in the network, and repeating the technique for all minimal cut sets generated with the search algorithm. The method functions equally well for planar and non-planar networks.

Interrater and test-retest reliability and validity of the Norwegian version of the BESTest and mini-BESTest in people with increased risk of falling.

Science.gov (United States)

Hamre, Charlotta; Botolfsen, Pernille; Tangen, Gro Gujord; Helbostad, Jorunn L

2017-04-20

The Balance Evaluation Systems Test (BESTest) was developed to assess underlying systems for balance control in order to be able to individually tailor rehabilitation interventions to people with balance disorders. A short form, the Mini-BESTest, was developed as a screening test. The study aimed to assess interrater and test-retest reliability of the Norwegian version of the BESTest and the Mini-BESTest in community-dwelling people with increased risk of falling and to assess concurrent validity with the Fall Efficacy Scale-International (FES-I), and it was an observational study with a cross-sectional design. Forty-two persons with increased risk of falling (elderly over 65 years of age, persons with a history of stroke or Multiple Sclerosis) were assessed twice by two raters. Relative reliability was analysed with Intraclass Correlation Coefficient (ICC), and absolute reliability with standard error of measurement (SEM) and smallest detectable change (SDC). Concurrent validity was assessed against the FES-I using Spearman's rho. The BESTest showed very good interrater reliability (ICC = 0.98, SEM = 1.79, SDC 95  = 5.0) and test-retest reliability (rater A/rater B = ICC = 0.89/0.89, SEM = 3.9/4.3, SDC 95  = 10.8/11.8). The Mini-BESTest also showed very good interrater reliability (ICC = 0.95, SEM = 1.19, SDC 95  = 3.3) and test-retest reliability (rater A/rater B = ICC = 0.85/0.84, SEM = 1.8/1.9, SDC 95  = 4.9/5.2). The correlations were moderate between the FES-I and both the BESTest and the Mini-BESTest (Spearman's rho -0.51 and-0.50, p test-retest reliability when assessed in a heterogeneous sample of people with increased risk of falling. The concurrent validity measured against the FES-I showed moderate correlation. The results are comparable with earlier studies and indicate that the Norwegian versions can be used in daily clinic and in research.

Development of integrated parameter database for risk assessment at the Rokkasho Reprocessing Plant

International Nuclear Information System (INIS)

Tamauchi, Yoshikazu

2011-01-01

A study to develop a parameter database for Probabilistic Safety Assessment (PSA) for the application of risk information on plant operation and maintenance activity is important because the transparency, consistency, and traceability of parameters are needed to explanation adequacy of the evaluation to third parties. Application of risk information for the plant operation and maintenance activity, equipment reliability data, human error rate, and 5 factors of 'five-factor formula' for estimation of the amount of radioactive material discharge (source term) are key inputs. As a part of the infrastructure development for the risk information application, we developed the integrated parameter database, 'R-POD' (Rokkasho reprocessing Plant Omnibus parameter Database) on the trial basis for the PSA of the Rokkasho Reprocessing Plant. This database consists primarily of the following 3 parts, 1) an equipment reliability database, 2) a five-factor formula database, and 3) a human reliability database. The underpinning for explaining the validity of the risk assessment can be improved by developing this database. Furthermore, this database is an important tool for the application of risk information, because it provides updated data by incorporating the accumulated operation experiences of the Rokkasho reprocessing plant. (author)

Reliability of histologic assessment in patients with eosinophilic oesophagitis.

Science.gov (United States)

Warners, M J; Ambarus, C A; Bredenoord, A J; Verheij, J; Lauwers, G Y; Walsh, J C; Katzka, D A; Nelson, S; van Viegen, T; Furuta, G T; Gupta, S K; Stitt, L; Zou, G; Parker, C E; Shackelton, L M; D Haens, G R; Sandborn, W J; Dellon, E S; Feagan, B G; Collins, M H; Jairath, V; Pai, R K

2018-04-01

The validity of the eosinophilic oesophagitis (EoE) histologic scoring system (EoEHSS) has been demonstrated, but only preliminary reliability data exist. Formally assess the reliability of the EoEHSS and additional histologic features. Four expert gastrointestinal pathologists independently reviewed slides from adult patients with EoE (N = 45) twice, in random order, using standardised training materials and scoring conventions for the EoEHSS and additional histologic features agreed upon during a modified Delphi process. Intra- and inter-rater reliability for scoring the EoEHSS, a visual analogue scale (VAS) of overall histopathologic disease severity, and additional histologic features were assessed using intra-class correlation coefficients (ICCs). Almost perfect intra-rater reliability was observed for the composite EoEHSS scores and the VAS. Inter-rater reliability was also almost perfect for the composite EoEHSS scores and substantial for the VAS. Of the EoEHSS items, eosinophilic inflammation was associated with the highest ICC estimates and consistent with almost perfect intra- and inter-rater reliability. With the exception of dyskeratotic epithelial cells and surface epithelial alteration, ICC estimates for the remaining EoEHSS items were above the benchmarks for substantial intra-rater, and moderate inter-rater reliability. Estimation of peak eosinophil count and number of lamina propria eosinophils were associated with the highest ICC estimates among the exploratory items. The composite EoEHSS and most component items are associated with substantial reliability when assessed by central pathologists. Future studies should assess responsiveness of the score to change after a therapeutic intervention to facilitate its use in clinical trials. © 2018 John Wiley & Sons Ltd.

Adaptation of the ToxRTool to Assess the Reliability of Toxicology Studies Conducted with Genetically Modified Crops and Implications for Future Safety Testing.

Science.gov (United States)

Koch, Michael S; DeSesso, John M; Williams, Amy Lavin; Michalek, Suzanne; Hammond, Bruce

2016-01-01

To determine the reliability of food safety studies carried out in rodents with genetically modified (GM) crops, a Food Safety Study Reliability Tool (FSSRTool) was adapted from the European Centre for the Validation of Alternative Methods' (ECVAM) ToxRTool. Reliability was defined as the inherent quality of the study with regard to use of standardized testing methodology, full documentation of experimental procedures and results, and the plausibility of the findings. Codex guidelines for GM crop safety evaluations indicate toxicology studies are not needed when comparability of the GM crop to its conventional counterpart has been demonstrated. This guidance notwithstanding, animal feeding studies have routinely been conducted with GM crops, but their conclusions on safety are not always consistent. To accurately evaluate potential risks from GM crops, risk assessors need clearly interpretable results from reliable studies. The development of the FSSRTool, which provides the user with a means of assessing the reliability of a toxicology study to inform risk assessment, is discussed. Its application to the body of literature on GM crop food safety studies demonstrates that reliable studies report no toxicologically relevant differences between rodents fed GM crops or their non-GM comparators.

Systems Analysis Programs for Hands-on Integrated Reliability Evaluations (SAPHIRE), Version 5.0: Integrated Reliability and Risk Analysis System (IRRAS) reference manual. Volume 2

International Nuclear Information System (INIS)

Russell, K.D.; Kvarfordt, K.J.; Skinner, N.L.; Wood, S.T.; Rasmuson, D.M.

1994-07-01

The Systems Analysis Programs for Hands-on Integrated Reliability Evaluations (SAPHIRE) refers to a set of several microcomputer programs that were developed to create and analyze probabilistic risk assessments (PRAs), primarily for nuclear power plants. The Integrated Reliability and Risk Analysis System (IRRAS) is a state-of-the-art, microcomputer-based probabilistic risk assessment (PRA) model development and analysis tool to address key nuclear plant safety issues. IRRAS is an integrated software tool that gives the use the ability to create and analyze fault trees and accident sequences using a microcomputer. This program provides functions that range from graphical fault tree construction to cut set generation and quantification to report generation. Version 1.0 of the IRRAS program was released in February of 1987. Since then, many user comments and enhancements have been incorporated into the program providing a much more powerful and user-friendly system. This version has been designated IRRAS 5.0 and is the subject of this Reference Manual. Version 5.0 of IRRAS provides the same capabilities as earlier versions and ads the ability to perform location transformations, seismic analysis, and provides enhancements to the user interface as well as improved algorithm performance. Additionally, version 5.0 contains new alphanumeric fault tree and event used for event tree rules, recovery rules, and end state partitioning

Nuclear Computerized Library for Assessing Reactor Reliability (NUCLARR): Volume 1, Summary description

International Nuclear Information System (INIS)

Gertman, D.I.; Gilmore, W.E.; Galyean, W.J.; Groh, M.R.; Gentillon, C.D.; Gilbert, B.G.

1988-02-01

A data management system has been implemented which supports a variety of risk-related analyses and provides a repository of hardware component failure and human error probability data to the risk analyst. The Nuclear Computerized Library for Assessing Reactor Reliability, NUCLARR, is an interactive, graphically oriented system which resides on a personal computer (PC) or PC-compatible environment. An overview of the data management system, including a description of data collection, specification, data structure, and taxonomies, is presented in Volume I of this report. Programming activities, procedures for processing data, user's guide, and hard copy data manual are presented in Volumes II through V

Risk assessment of nickel carcinogenicity and occupational lung cancer.

OpenAIRE

Shen, H M; Zhang, Q F

1994-01-01

Recent progress in risk assessment of nickel carcinogenicity and its correlation with occupational lung cancer in nickel-exposed workers is reviewed. Epidemiological investigations provide reliable data indicating the close relation between nickel exposure and high lung cancer risk, especially in nickel refineries. The nickel species-specific effects and the dose-response relationship between nickel exposure and lung cancer are among the main questions that are explored extensively. It is als...

Assessment of structural reliability of precast concrete buildings

Directory of Open Access Journals (Sweden)

Koyankin Alexandr

2018-01-01

Full Text Available Precast housing construction is currently being under rapid development, however, reliability of building structures made from precast reinforced concrete cannot be assessed rationally due to insufficient research data on that subject. In this regard, experimental and numerical studies were conducted to assess structural reliability of precast buildings as described in the given paper. Experimental studies of full-scale and model samples were conducted; numerical studies were held based on finite element models using “Lira” software. The objects under study included fragment of flooring of a building under construction, full-size fragment of flooring, full-scale models of precast cross-beams-to-columns joints and joints between hollow-core floor slabs and precast and cast-in-place cross-beams. Conducted research enabled to perform an objective assessment of structural reliability of precast buildings.

Optimal Bi-Objective Redundancy Allocation for Systems Reliability and Risk Management

DEFF Research Database (Denmark)

Govindan, Kannan; Jafarian, Ahmad; Azbari, Mostafa E.

2016-01-01

In the big data era, systems reliability is critical to effective systems risk management. In this paper, a novel multiobjective approach, with hybridization of a known algorithm called NSGA-II and an adaptive population-based simulated annealing (APBSA) method is developed to solve the systems...... of domination; and 4) data envelopment analysis. The computational studies have shown that the proposed algorithm is an effective approach for systems reliability and risk management....

An overview of the evolution of human reliability analysis in the context of probabilistic risk assessment

International Nuclear Information System (INIS)

Bley, Dennis C.; Lois, Erasmia; Kolaczkowski, Alan M.; Forester, John Alan; Wreathall, John; Cooper, Susan E.

2009-01-01

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

An overview of the evolution of human reliability analysis in the context of probabilistic risk assessment.

Energy Technology Data Exchange (ETDEWEB)

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)

2009-01-01

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.

Hypsarrhythmia assessment exhibits poor interrater reliability: a threat to clinical trial validity.

Science.gov (United States)

Hussain, Shaun A; Kwong, Grace; Millichap, John J; Mytinger, John R; Ryan, Nicole; Matsumoto, Joyce H; Wu, Joyce Y; Lerner, Jason T; Sankar, Raman

2015-01-01

Hypsarrhythmia is the classic interictal electroencephalographic pattern associated with infantile spasms, and characterized by high voltage, disorganization, and multifocal independent epileptiform discharges. Given this seemingly simple definition, one might expect excellent interrater reliability (IRR) in the identification of this pattern. Alternatively, it may be argued that assessments of voltage and disorganization are fairly subjective, and thus quite challenging in borderline cases. We sought to test the IRR of hypsarrhythmia assessment in a systematic fashion. Six blinded pediatric electroencephalographers from four centers reviewed 22 electroencephalography (EEG) samples from patients with infantile spasms. Each sample was 5 min in duration and included only wakefulness. Raters determined if each EEG was abnormal and if hypsarrhythmia was present/absent, and characterized relevant features: voltage, organization, epileptiform discharges, slowing, interictal attenuations, symmetry, and synchrony. In addition, raters indicated their level of confidence for each assessment. Multirater kappa statistics (κ) were calculated for the assessment of hypsarrhythmia and each feature. Although IRR was favorable in determining whether a study was normal or abnormal (κ=0.89), reliability was unfavorable for assessment of hypsarrhythmia (κ=0.40), modified hypsarrhythmia (κ=0.47), high voltage (κ=0.37), disorganization (κ=0.22), multifocal epileptiform discharges (κ=0.68), interictal voltage attenuations (κ=0.21), slowing (κ=0.20), asymmetry (κ=0.26), and asynchrony (κ=0.08). Despite generally unsatisfactory interrater agreement, raters consistently reported high confidence in assessments. This study contradicts the view that hypsarrhythmia assessment is straightforward. Even small variability in the identification of hypsarrhythmia has potentially deleterious consequences for clinical care, as its presence or absence impacts decisions to pursue high-risk and

A new measurement of workload in Web application reliability assessment

Directory of Open Access Journals (Sweden)

CUI Xia

2015-02-01

Full Text Available Web application has been popular in various fields of social life.It becomes more and more important to study the reliability of Web application.In this paper the definition of Web application failure is firstly brought out,and then the definition of Web application reliability.By analyzing data in the IIS server logs and selecting corresponding usage and information delivery failure data,the paper study the feasibility of Web application reliability assessment from the perspective of Web software system based on IIS server logs.Because the usage for a Web site often has certain regularity,a new measurement of workload in Web application reliability assessment is raised.In this method,the unit is removed by weighted average technique;and the weights are assessed by setting objective function and optimization.Finally an experiment was raised for validation.The experiment result shows the assessment of Web application reliability base on the new workload is better.

Sequential optimization and reliability assessment method for metal forming processes

International Nuclear Information System (INIS)

Sahai, Atul; Schramm, Uwe; Buranathiti, Thaweepat; Chen Wei; Cao Jian; Xia, Cedric Z.

2004-01-01

Uncertainty is inevitable in any design process. The uncertainty could be due to the variations in geometry of the part, material properties or due to the lack of knowledge about the phenomena being modeled itself. Deterministic design optimization does not take uncertainty into account and worst case scenario assumptions lead to vastly over conservative design. Probabilistic design, such as reliability-based design and robust design, offers tools for making robust and reliable decisions under the presence of uncertainty in the design process. Probabilistic design optimization often involves double-loop procedure for optimization and iterative probabilistic assessment. This results in high computational demand. The high computational demand can be reduced by replacing computationally intensive simulation models with less costly surrogate models and by employing Sequential Optimization and reliability assessment (SORA) method. The SORA method uses a single-loop strategy with a series of cycles of deterministic optimization and reliability assessment. The deterministic optimization and reliability assessment is decoupled in each cycle. This leads to quick improvement of design from one cycle to other and increase in computational efficiency. This paper demonstrates the effectiveness of Sequential Optimization and Reliability Assessment (SORA) method when applied to designing a sheet metal flanging process. Surrogate models are used as less costly approximations to the computationally expensive Finite Element simulations

Integrated probabilistic risk assessment for nanoparticles: the case of nanosilica in food.

Science.gov (United States)

Jacobs, Rianne; van der Voet, Hilko; Ter Braak, Cajo J F

Insight into risks of nanotechnology and the use of nanoparticles is an essential condition for the social acceptance and safe use of nanotechnology. One of the problems with which the risk assessment of nanoparticles is faced is the lack of data, resulting in uncertainty in the risk assessment. We attempt to quantify some of this uncertainty by expanding a previous deterministic study on nanosilica (5-200 nm) in food into a fully integrated probabilistic risk assessment. We use the integrated probabilistic risk assessment method in which statistical distributions and bootstrap methods are used to quantify uncertainty and variability in the risk assessment. Due to the large amount of uncertainty present, this probabilistic method, which separates variability from uncertainty, contributed to a better understandable risk assessment. We found that quantifying the uncertainties did not increase the perceived risk relative to the outcome of the deterministic study. We pinpointed particular aspects of the hazard characterization that contributed most to the total uncertainty in the risk assessment, suggesting that further research would benefit most from obtaining more reliable data on those aspects.

Integrated probabilistic risk assessment for nanoparticles: the case of nanosilica in food

International Nuclear Information System (INIS)

Jacobs, Rianne; Voet, Hilko van der; Braak, Cajo J. F. ter

2015-01-01

Insight into risks of nanotechnology and the use of nanoparticles is an essential condition for the social acceptance and safe use of nanotechnology. One of the problems with which the risk assessment of nanoparticles is faced is the lack of data, resulting in uncertainty in the risk assessment. We attempt to quantify some of this uncertainty by expanding a previous deterministic study on nanosilica (5–200 nm) in food into a fully integrated probabilistic risk assessment. We use the integrated probabilistic risk assessment method in which statistical distributions and bootstrap methods are used to quantify uncertainty and variability in the risk assessment. Due to the large amount of uncertainty present, this probabilistic method, which separates variability from uncertainty, contributed to a better understandable risk assessment. We found that quantifying the uncertainties did not increase the perceived risk relative to the outcome of the deterministic study. We pinpointed particular aspects of the hazard characterization that contributed most to the total uncertainty in the risk assessment, suggesting that further research would benefit most from obtaining more reliable data on those aspects

Integrated probabilistic risk assessment for nanoparticles: the case of nanosilica in food

Energy Technology Data Exchange (ETDEWEB)

Jacobs, Rianne, E-mail: rianne.jacobs@wur.nl; Voet, Hilko van der; Braak, Cajo J. F. ter [Wageningen University and Research Centre, Biometris (Netherlands)

2015-06-15

Insight into risks of nanotechnology and the use of nanoparticles is an essential condition for the social acceptance and safe use of nanotechnology. One of the problems with which the risk assessment of nanoparticles is faced is the lack of data, resulting in uncertainty in the risk assessment. We attempt to quantify some of this uncertainty by expanding a previous deterministic study on nanosilica (5–200 nm) in food into a fully integrated probabilistic risk assessment. We use the integrated probabilistic risk assessment method in which statistical distributions and bootstrap methods are used to quantify uncertainty and variability in the risk assessment. Due to the large amount of uncertainty present, this probabilistic method, which separates variability from uncertainty, contributed to a better understandable risk assessment. We found that quantifying the uncertainties did not increase the perceived risk relative to the outcome of the deterministic study. We pinpointed particular aspects of the hazard characterization that contributed most to the total uncertainty in the risk assessment, suggesting that further research would benefit most from obtaining more reliable data on those aspects.

Data banks for risk assessment at the Savannah River Site

International Nuclear Information System (INIS)

Durant, W.S.; Townsend, C.S.; Baughman, D.F.; Hang, P.

1992-01-01

One of the lessons learned from many years of risk assessment experience is that mistakes of the past are soon forgotten if no method is available to retrieve and review these events. Savannah River Site has maintained a computerized data bank system for recording, retrieving and reviewing its incident history. The system is based on a series of compilations developed primarily for risk assessment but has been found to be invaluable for many other uses such as equipment reliability, project justification, and incident investigations

Quantification of human reliability in probabilistic safety assessment

International Nuclear Information System (INIS)

Hirschberg, S.; Dankg, Vinh N.

1996-01-01

Human performance may substantially influence the reliability and safety of complex technical systems. For this reason, Human Reliability Analysis (HRA) constitutes an important part of Probabilistic Safety Assessment (PSAs) or Quantitative Risk Analyses (QRAs). The results of these studies as well as analyses of past accidents and incidents clearly demonstrate the importance of human interactions. The contribution of human errors to the core damage frequency (CDF), as estimated in the Swedish nuclear PSAs, are between 15 and 88%. A survey of the FRAs in the Swiss PSAs shows that also for the Swiss nuclear power plants the estimated HE contributions are substantial (49% of the CDF due to internal events in the case of Beznau and 70% in the case of Muehleberg; for the total CDF, including external events, 25% respectively 20%). Similar results can be extracted from the PSAs carried out for French, German, and US plants. In PSAs or QRAs, the adequate treatment of the human interactions with the system is a key to the understanding of accident sequences and their relative importance to overall risk. The main objectives of HRA are: first, to ensure that the key human interactions are systematically identified and incorporated into the safety analysis in a traceable manner, and second, to quantify the probabilities of their success and failure. Adopting a structured and systematic approach to the assessment of human performance makes it possible to provide greater confidence that the safety and availability of human-machine systems is not unduly jeopardized by human performance problems. Section 2 discusses the different types of human interactions analysed in PSAs. More generally, the section presents how HRA fits in the overall safety analysis, that is, how the human interactions to be quantified are identified. Section 3 addresses the methods for quantification. Section 4 concludes the paper by presenting some recommendations and pointing out the limitations of the

Portfolio assessment during medical internships: How to obtain a reliable and feasible assessment procedure?

Science.gov (United States)

Michels, Nele R M; Driessen, Erik W; Muijtjens, Arno M M; Van Gaal, Luc F; Bossaert, Leo L; De Winter, Benedicte Y

2009-12-01

A portfolio is used to mentor and assess students' clinical performance at the workplace. However, students and raters often perceive the portfolio as a time-consuming instrument. In this study, we investigated whether assessment during medical internship by a portfolio can combine reliability and feasibility. The domain-oriented reliability of 61 double-rated portfolios was measured, using a generalisability analysis with portfolio tasks and raters as sources of variation in measuring the performance of a student. We obtained reliability (Phi coefficient) of 0.87 with this internship portfolio containing 15 double-rated tasks. The generalisability analysis showed that an acceptable level of reliability (Phi = 0.80) was maintained when the amount of portfolio tasks was decreased to 13 or 9 using one and two raters, respectively. Our study shows that a portfolio can be a reliable method for the assessment of workplace learning. The possibility of reducing the amount of tasks or raters while maintaining a sufficient level of reliability suggests an increase in feasibility of portfolio use for both students and raters.

Reliability assessment of Port Harcourt 33/11kv Distribution System ...

African Journals Online (AJOL)

This makes reliability studies an important task besides all the other analyses required for assessing the system performance. The paper presents an analytical approach in the reliability assessment of the Port Harcourt 33/11kV power distribution system. The assessment was performed with the 2009 power outage data ...

Reliability of sonographic assessment of tendinopathy in tennis elbow.

Science.gov (United States)

Poltawski, Leon; Ali, Syed; Jayaram, Vijay; Watson, Tim

2012-01-01

To assess the reliability and compute the minimum detectable change using sonographic scales to quantify the extent of pathology and hyperaemia in the common extensor tendon in people with tennis elbow. The lateral elbows of 19 people with tennis elbow were assessed sonographically twice, 1-2 weeks apart. Greyscale and power Doppler images were recorded for subsequent rating of abnormalities. Tendon thickening, hypoechogenicity, fibrillar disruption and calcification were each rated on four-point scales, and scores were summed to provide an overall rating of structural abnormality; hyperaemia was scored on a five point scale. Inter-rater reliability was established using the intraclass correlation coefficient (ICC) to compare scores assigned independently to the same set of images by a radiologist and a physiotherapist with training in musculoskeletal imaging. Test-retest reliability was assessed by comparing scores assigned by the physiotherapist to images recorded at the two sessions. The minimum detectable change (MDC) was calculated from the test-retest reliability data. ICC values for inter-rater reliability ranged from 0.35 (95% CI: 0.05, 0.60) for fibrillar disruption to 0.77 (0.55, 0.88) for overall greyscale score, and 0.89 (0.79, 0.95) for hyperaemia. Test-retest reliability ranged from 0.70 (0.48, 0.84) for tendon thickening to 0.82 (0.66, 0.90) for overall greyscale score and 0.86 (0.73, 0.93) for calcification. The MDC for the greyscale total score was 2.0/12 and for the hyperaemia score was 1.1/5. The sonographic scoring system used in this study may be used reliably to quantify tendon abnormalities and change over time. A relatively inexperienced imager can conduct the assessment and use the rating scales reliably.

Method for assessing reliability of a network considering probabilistic safety assessment

International Nuclear Information System (INIS)

Cepin, M.

2005-01-01

A method for assessment of reliability of the network is developed, which uses the features of the fault tree analysis. The method is developed in a way that the increase of the network under consideration does not require significant increase of the model. The method is applied to small examples of network consisting of a small number of nodes and a small number of their connections. The results give the network reliability. They identify equipment, which is to be carefully maintained in order that the network reliability is not reduced, and equipment, which is a candidate for redundancy, as this would improve network reliability significantly. (author)

Risk and dose assessment methods in gamma knife QA

International Nuclear Information System (INIS)

Banks, W.W.; Jones, E.D.; Rathbun, P.

1992-10-01

Traditional methods used in assessing risk in nuclear power plants may be inappropriate to use in assessing medical radiation risks. The typical philosophy used in assessing nuclear reactor risks is machine dominated with only secondary attention paid to the human component, and only after critical machine failure events have been identified. In assessing the risk of a misadministrative radiation dose to patients, the primary source of failures seems to stem overwhelmingly, from the actions of people and only secondarily from machine mode failures. In essence, certain medical misadministrations are dominated by human events not machine failures. Radiological medical devices such as the Leksell Gamma Knife are very simple in design, have few moving parts, and are relatively free from the risks of wear when compared with a nuclear power plant. Since there are major technical differences between a gamma knife and a nuclear power plant, one must select a particular risk assessment method which is sensitive to these system differences and tailored to the unique medical aspects of the phenomena under study. These differences also generate major shifts in the philosophy and assumptions which drive the risk assessment (Machine-centered vs Person-centered) method. We were prompted by these basic differences to develop a person-centered approach to risk assessment which would reflect these basic philosophical and technological differences, have the necessary resolution in its metrics, and be highly reliable (repeatable). The risk approach chosen by the Livermore investigative team has been called the ''Relative Risk Profile Method'' and has been described in detail by Banks and Paramore, (1983)

Quantum chemistry in environmental pesticide risk assessment.

Science.gov (United States)

Villaverde, Juan J; López-Goti, Carmen; Alcamí, Manuel; Lamsabhi, Al Mokhtar; Alonso-Prados, José L; Sandín-España, Pilar

2017-11-01

The scientific community and regulatory bodies worldwide, currently promote the development of non-experimental tests that produce reliable data for pesticide risk assessment. The use of standard quantum chemistry methods could allow the development of tools to perform a first screening of compounds to be considered for the experimental studies, improving the risk assessment. This fact results in a better distribution of resources and in better planning, allowing a more exhaustive study of the pesticides and their metabolic products. The current paper explores the potential of quantum chemistry in modelling toxicity and environmental behaviour of pesticides and their by-products by using electronic descriptors obtained computationally. Quantum chemistry has potential to estimate the physico-chemical properties of pesticides, including certain chemical reaction mechanisms and their degradation pathways, allowing modelling of the environmental behaviour of both pesticides and their by-products. In this sense, theoretical methods can contribute to performing a more focused risk assessment of pesticides used in the market, and may lead to higher quality and safer agricultural products. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

Above, Beyond, and Over the Side rails: Evaluating the New Memorial Emergency Department Fall-Risk-Assessment Tool.

Science.gov (United States)

Scott, Robin A; Oman, Kathleen S; Flarity, Kathleen; Comer, Jennifer L

2018-03-06

Patient falls are a significant issue in hospitalized patients and financially costly to hospitals. The Joint Commission requires that patients be assessed for fall risk and interventions in place to mitigate the risk of falls. It is imperative to have a patient population/setting specific fall risk assessment tool to identify patients at risk for falling. The purpose of this study was to evaluate the reliability and validity of the 2013 Memorial ED Fall Risk Assessment tool (MEDFRAT) specifically designed for the ED population. A two-phase prospective design was used for this study. Phase one determined the interrater reliability of the MEDFRAT. Phase two assessed the validity of the MEDFRAT in an emergency department (ED) within a 600-bed academic/teaching institution; Level II Trauma Center with >100,000 annual patient visits. The Memorial ED Fall Risk Assessment Tool was validated in this ED setting. The tool demonstrated positive interrater reliability (k=0.701) and when implemented with a falls prevention strategy and staff education demonstrated a 48% decrease in ED fall rate (0.57 falls/1000 patient visits) post implementation during the study period. The MEDFRAT, an evidenced based ED-specific fall risk tool was implemented on the basis of the risk factors consistently identified in the literature: prior fall history, impaired mobility, altered mental status, altered elimination, and the use of sedative medication. The Memorial ED Fall Risk Assessment Tool demonstrated to be a valid tool for this hospital system. Copyright © 2018 Emergency Nurses Association. Published by Elsevier Inc. All rights reserved.

Reliability assessment of complex electromechanical systems under epistemic uncertainty

International Nuclear Information System (INIS)

Mi, Jinhua; Li, Yan-Feng; Yang, Yuan-Jian; Peng, Weiwen; Huang, Hong-Zhong

2016-01-01

The appearance of macro-engineering and mega-project have led to the increasing complexity of modern electromechanical systems (EMSs). The complexity of the system structure and failure mechanism makes it more difficult for reliability assessment of these systems. Uncertainty, dynamic and nonlinearity characteristics always exist in engineering systems due to the complexity introduced by the changing environments, lack of data and random interference. This paper presents a comprehensive study on the reliability assessment of complex systems. In view of the dynamic characteristics within the system, it makes use of the advantages of the dynamic fault tree (DFT) for characterizing system behaviors. The lifetime of system units can be expressed as bounded closed intervals by incorporating field failures, test data and design expertize. Then the coefficient of variation (COV) method is employed to estimate the parameters of life distributions. An extended probability-box (P-Box) is proposed to convey the present of epistemic uncertainty induced by the incomplete information about the data. By mapping the DFT into an equivalent Bayesian network (BN), relevant reliability parameters and indexes have been calculated. Furthermore, the Monte Carlo (MC) simulation method is utilized to compute the DFT model with consideration of system replacement policy. The results show that this integrated approach is more flexible and effective for assessing the reliability of complex dynamic systems. - Highlights: • A comprehensive study on the reliability assessment of complex system is presented. • An extended probability-box is proposed to convey the present of epistemic uncertainty. • The dynamic fault tree model is built. • Bayesian network and Monte Carlo simulation methods are used. • The reliability assessment of a complex electromechanical system is performed.

Reliability and Failure in NASA Missions: Blunders, Normal Accidents, High Reliability, Bad Luck

Science.gov (United States)

Jones, Harry W.

2015-01-01

NASA emphasizes crew safety and system reliability but several unfortunate failures have occurred. The Apollo 1 fire was mistakenly unanticipated. After that tragedy, the Apollo program gave much more attention to safety. The Challenger accident revealed that NASA had neglected safety and that management underestimated the high risk of shuttle. Probabilistic Risk Assessment was adopted to provide more accurate failure probabilities for shuttle and other missions. NASA's "faster, better, cheaper" initiative and government procurement reform led to deliberately dismantling traditional reliability engineering. The Columbia tragedy and Mars mission failures followed. Failures can be attributed to blunders, normal accidents, or bad luck. Achieving high reliability is difficult but possible.

Student Precision and Reliability of the Team Sport Assessment in ...

African Journals Online (AJOL)

TSAP) and formative assessment of invasion sport. The specific objectives were to determine the degree of agreement among expert observers, inter-observer reliability (internal consistency), and intra observer reliability (temporal reliability).

Reliability of the ECHOWS Tool for Assessment of Patient Interviewing Skills.

Science.gov (United States)

Boissonnault, Jill S; Evans, Kerrie; Tuttle, Neil; Hetzel, Scott J; Boissonnault, William G

2016-04-01

History taking is an important component of patient/client management. Assessment of student history-taking competency can be achieved via a standardized tool. The ECHOWS tool has been shown to be valid with modest intrarater reliability in a previous study but did not demonstrate sufficient power to definitively prove its stability. The purposes of this study were: (1) to assess the reliability of the ECHOWS tool for student assessment of patient interviewing skills and (2) to determine whether the tool discerns between novice and experienced skill levels. A reliability and construct validity assessment was conducted. Three faculty members from the United States and Australia scored videotaped histories from standardized patients taken by students and experienced clinicians from each of these countries. The tapes were scored twice, 3 to 6 weeks apart. Reliability was assessed using interclass correlation coefficients (ICCs) and repeated measures. Analysis of variance models assessed the ability of the tool to discern between novice and experienced skill levels. The ECHOWS tool showed excellent intrarater reliability (ICC [3,1]=.74-.89) and good interrater reliability (ICC [2,1]=.55) as a whole. The summary of performance (S) section showed poor interrater reliability (ICC [2,1]=.27). There was no statistical difference in performance on the tool between novice and experienced clinicians. A possible ceiling effect may occur when standardized patients are not coached to provide complex and obtuse responses to interviewer questions. Variation in familiarity with the ECHOWS tool and in use of the online training may have influenced scoring of the S section. The ECHOWS tool demonstrates excellent intrarater reliability and moderate interrater reliability. Sufficient training with the tool prior to student assessment is recommended. The S section must evolve in order to provide a more discerning measure of interviewing skills. © 2016 American Physical Therapy

Cost Model for Risk Assessment of Company Operation in Audit

Directory of Open Access Journals (Sweden)

S. V.

2017-12-01

Full Text Available This article explores the approach to assessing the risk of company activities termination by building a cost model. This model gives auditors information on managers’ understanding of factors influencing change in the value of assets and liabilities, and the methods to identify it in more effective and reliable ways. Based on this information, the auditor can assess the adequacy of use of the assumption on continuity of company operation by management personnel when preparing financial statements. Financial uncertainty entails real manifestations of factors creating risks of the occurrence of costs, revenue losses due their manifestations, which in the long run can be a reason for termination of company operation, and, therefore, need to be foreseen in the auditor’s assessment of the adequacy of use of the continuity assumption when preparing financial statements by company management. The purpose of the study is to explore and develop a methodology for use of cost models to assess the risk of termination of company operation in audit. The issue of methodology for assessing the audit risk through analyzing methods for company valuation has not been dealt with. The review of methodologies for assessing the risks of termination of company operation in course of audit gives grounds for the conclusion that use of cost models can be an effective methodology for identification and assessment of such risks. The analysis of the above methods gives understanding of the existing system for company valuation, integrated into the management system, and the consequences of its use, i. e. comparison of the asset price data with the accounting data and the market value of the asset data. Overvalued or undervalued company assets may be a sign of future sale or liquidation of a company, which may signal on high probability of termination of company operation. A wrong choice or application of valuation methods can be indicative of the risk of non-reliable

Exploring the interactions between forecast accuracy, risk perception and perceived forecast reliability in reservoir operator's decision to use forecast

Science.gov (United States)

Shafiee-Jood, M.; Cai, X.

2017-12-01

Advances in streamflow forecasts at different time scales offer a promise for proactive flood management and improved risk management. Despite the huge potential, previous studies have found that water resources managers are often not willing to incorporate streamflow forecasts information in decisions making, particularly in risky situations. While low accuracy of forecasts information is often cited as the main reason, some studies have found that implementation of streamflow forecasts sometimes is impeded by institutional obstacles and behavioral factors (e.g., risk perception). In fact, a seminal study by O'Connor et al. (2005) found that risk perception is the strongest determinant of forecast use while managers' perception about forecast reliability is not significant. In this study, we aim to address this issue again. However, instead of using survey data and regression analysis, we develop a theoretical framework to assess the user-perceived value of streamflow forecasts. The framework includes a novel behavioral component which incorporates both risk perception and perceived forecast reliability. The framework is then used in a hypothetical problem where reservoir operator should react to probabilistic flood forecasts with different reliabilities. The framework will allow us to explore the interactions among risk perception and perceived forecast reliability, and among the behavioral components and information accuracy. The findings will provide insights to improve the usability of flood forecasts information through better communication and education.

Rapid Response Risk Assessment in New Project Development

Science.gov (United States)

Graber, Robert R.

2010-01-01

A capability for rapidly performing quantitative risk assessments has been developed by JSC Safety and Mission Assurance for use on project design trade studies early in the project life cycle, i.e., concept development through preliminary design phases. A risk assessment tool set has been developed consisting of interactive and integrated software modules that allow a user/project designer to assess the impact of alternative design or programmatic options on the probability of mission success or other risk metrics. The risk and design trade space includes interactive options for selecting parameters and/or metrics for numerous design characteristics including component reliability characteristics, functional redundancy levels, item or system technology readiness levels, and mission event characteristics. This capability is intended for use on any project or system development with a defined mission, and an example project will used for demonstration and descriptive purposes, e.g., landing a robot on the moon. The effects of various alternative design considerations and their impact of these decisions on mission success (or failure) can be measured in real time on a personal computer. This capability provides a high degree of efficiency for quickly providing information in NASA s evolving risk-based decision environment

Suprahyoid Muscle Complex: A Reliable Neural Assessment Tool For Dysphagia?

DEFF Research Database (Denmark)

Kothari, Mohit; Stubbs, Peter William; Pedersen, Asger Roer

be a non-invasive reliable neural assessment tool for patients with dysphagia. Objective: To investigate the possibility of using the suprahyoid muscle complex (SMC) using surface electromyography (sEMG) to assess changes to neural pathways by determining the reliability of measurements in healthy...

Assessment and Improving Methods of Reliability Indices in Bakhtar Regional Electricity Company

Directory of Open Access Journals (Sweden)

Saeed Shahrezaei

2013-04-01

Full Text Available Reliability of a system is the ability of a system to do prospected duties in future and the probability of desirable operation for doing predetermined duties. Power system elements failures data are the main data of reliability assessment in the network. Determining antiseptic parameters is the goal of reliability assessment by using system history data. These parameters help to recognize week points of the system. In other words, the goal of reliability assessment is operation improving and decreasing of the failures and power outages. This paper is developed to assess reliability indices of Bakhtar Regional Electricity Company up to 1393 and the improving methods and their effects on the reliability indices in this network. DIgSILENT Power Factory software is employed for simulation. Simulation results show the positive effect of improving methods in reliability indices of Bakhtar Regional Electricity Company.

Human reliability analysis methods for probabilistic safety assessment

International Nuclear Information System (INIS)

Pyy, P.

2000-11-01

Human reliability analysis (HRA) of a probabilistic safety assessment (PSA) includes identifying human actions from safety point of view, modelling the most important of them in PSA models, and assessing their probabilities. As manifested by many incidents and studies, human actions may have both positive and negative effect on safety and economy. Human reliability analysis is one of the areas of probabilistic safety assessment (PSA) that has direct applications outside the nuclear industry. The thesis focuses upon developments in human reliability analysis methods and data. The aim is to support PSA by extending the applicability of HRA. The thesis consists of six publications and a summary. The summary includes general considerations and a discussion about human actions in the nuclear power plant (NPP) environment. A condensed discussion about the results of the attached publications is then given, including new development in methods and data. At the end of the summary part, the contribution of the publications to good practice in HRA is presented. In the publications, studies based on the collection of data on maintenance-related failures, simulator runs and expert judgement are presented in order to extend the human reliability analysis database. Furthermore, methodological frameworks are presented to perform a comprehensive HRA, including shutdown conditions, to study reliability of decision making, and to study the effects of wrong human actions. In the last publication, an interdisciplinary approach to analysing human decision making is presented. The publications also include practical applications of the presented methodological frameworks. (orig.)

Reliability-based assessment of flow assurance of hot waxy crude pipelines

Energy Technology Data Exchange (ETDEWEB)

Jinjun, Zhang; Wenke, Zhang; Jianlin, Ding; Bo, Yu [China University of Petroleum - Beijing (CUPB), Beijing (China)

2009-07-01

Waxy crude is characterized by its high pour point. Pipeline blockage may occur after prolonged shutdown of a pipeline due to crude oil gelation. Another flow assurance problem is the instable operation at a flow rate below the lowest allowable operation flow rate which is dependent on heat transfer of the pipeline and the viscosity vs. temperature relation of the crude pumped. Besides, for pipelines with thick wax deposition layer, massive depletion of wax deposit in some cases such as pipeline restart at high expelling pressure may also result in blockage of the pipeline, and the pig may be jammed during pigging as a result of thick wax deposition. Conventionally, assessment of these risks has been made by using the deterministic approach. However, many related physical quantities are subject to uncertainty and contribute to reliability of flow assurance. Therefore, the probabilistic approach is suggested and a framework of reliability based assessment of flow assurance of waxy crude pipelines is proposed in this paper. Discussions are also made on the limit state functions and target safety level. In the future study, development of an efficient and robust stochastic-numerical method is crucial. (author)

Reliability Assessment and Reliability-Based Inspection and Maintenance of Offshore Wind Turbines

DEFF Research Database (Denmark)

Ramirez, José Rangel

actions are the most relevant and effective means of control of deterioration. The risk-based inspection planning methodology, based on Bayesian decision theory, represents an important tool to identify the suitable strategy to inspect and control the deterioration in structures such as offshore wind...... performance during the life cycle. The deterioration processes, such as fatigue and corrosion, are typically affecting offshore structural systems. This damage decreases the system performance and increases the risk of failure, thus not fulfilling the established safety criteria. Inspection and maintenance...... to their offshore location, no pollution risks and low human risks since they are unmanned. This allows the allocation of lower reliability level compared to e.g. oil & gas installations. With the incursion to water depths between 20 and 50 meters, the use of jacket and tripod structures represents a feasible...

Psychometrics of the Iowa and Berlin Gambling Tasks: Unresolved Issues With Reliability and Validity for Risk Taking.

Science.gov (United States)

Schmitz, Florian; Kunina-Habenicht, Olga; Hildebrandt, Andrea; Oberauer, Klaus; Wilhelm, Oliver

2018-01-01

The Iowa Gambling Task (IGT) is one of the most prominent paradigms employed for the assessment of risk taking in the laboratory, and it was shown to distinguish between various patient groups and controls. The present study was conducted to test the psychometric characteristics of the original IGT and of a new gambling task variant for assessing individual differences. Two studies were conducted with adults of the general population ( n = 220) and with adolescents ( n = 389). Participants were also tested on multiple measures of working memory capacity, fluid intelligence, personality traits associated with risk-taking behavior, and self-reported risk taking in various domains. Both gambling tasks had only moderate retest reliability within the same session. Moderate relations were obtained with cognitive ability. However, card selections in the gambling tasks were not correlated with personality or risk taking. These findings point to limitations of IGT type gambling tasks for the assessment of individual differences in risky decision making.

Reliability of assessment of adherence to an antimicrobial treatment guideline

NARCIS (Netherlands)

Mol, PGM; Gans, ROB; Panday, PVN; Degener, JE; Laseur, M; Haaijer-Ruskamp, FM

Assessment procedures for adherence to a guideline must be reliable and credible. The aim of this study was to explore the reliability of assessment of adherence, taking account of the professional backgrounds of the observers. A secondary analysis explored the impact of case characteristics on

Environmental Risk Assessment Strategy for Nanomaterials

Directory of Open Access Journals (Sweden)

Janeck J. Scott‐Fordsmand

2017-10-01

Full Text Available An Environmental Risk Assessment (ERA for nanomaterials (NMs is outlined in this paper. Contrary to other recent papers on the subject, the main data requirements, models and advancement within each of the four risk assessment domains are described, i.e., in the: (i materials, (ii release, fate and exposure, (iii hazard and (iv risk characterisation domains. The material, which is obviously the foundation for any risk assessment, should be described according to the legislatively required characterisation data. Characterisation data will also be used at various levels within the ERA, e.g., exposure modelling. The release, fate and exposure data and models cover the input for environmental distribution models in order to identify the potential (PES and relevant exposure scenarios (RES and, subsequently, the possible release routes, both with regard to which compartment(s NMs are distributed in line with the factors determining the fate within environmental compartment. The initial outcome in the risk characterisation will be a generic Predicted Environmental Concentration (PEC, but a refined PEC can be obtained by applying specific exposure models for relevant media. The hazard information covers a variety of representative, relevant and reliable organisms and/or functions, relevant for the RES and enabling a hazard characterisation. The initial outcome will be hazard characterisation in test systems allowing estimating a Predicted No-Effect concentration (PNEC, either based on uncertainty factors or on a NM adapted version of the Species Sensitivity Distributions approach. The risk characterisation will either be based on a deterministic risk ratio approach (i.e., PEC/PNEC or an overlay of probability distributions, i.e., exposure and hazard distributions, using the nano relevant models.

Environmental Risk Assessment Strategy for Nanomaterials.

Science.gov (United States)

Scott-Fordsmand, Janeck J; Peijnenburg, Willie J G M; Semenzin, Elena; Nowack, Bernd; Hunt, Neil; Hristozov, Danail; Marcomini, Antonio; Irfan, Muhammad-Adeel; Jiménez, Araceli Sánchez; Landsiedel, Robert; Tran, Lang; Oomen, Agnes G; Bos, Peter M J; Hund-Rinke, Kerstin

2017-10-19

An Environmental Risk Assessment (ERA) for nanomaterials (NMs) is outlined in this paper. Contrary to other recent papers on the subject, the main data requirements, models and advancement within each of the four risk assessment domains are described, i.e., in the: (i) materials, (ii) release, fate and exposure, (iii) hazard and (iv) risk characterisation domains. The material, which is obviously the foundation for any risk assessment, should be described according to the legislatively required characterisation data. Characterisation data will also be used at various levels within the ERA, e.g., exposure modelling. The release, fate and exposure data and models cover the input for environmental distribution models in order to identify the potential (PES) and relevant exposure scenarios (RES) and, subsequently, the possible release routes, both with regard to which compartment(s) NMs are distributed in line with the factors determining the fate within environmental compartment. The initial outcome in the risk characterisation will be a generic Predicted Environmental Concentration (PEC), but a refined PEC can be obtained by applying specific exposure models for relevant media. The hazard information covers a variety of representative, relevant and reliable organisms and/or functions, relevant for the RES and enabling a hazard characterisation. The initial outcome will be hazard characterisation in test systems allowing estimating a Predicted No-Effect concentration (PNEC), either based on uncertainty factors or on a NM adapted version of the Species Sensitivity Distributions approach. The risk characterisation will either be based on a deterministic risk ratio approach (i.e., PEC/PNEC) or an overlay of probability distributions, i.e., exposure and hazard distributions, using the nano relevant models.

Statistical reliability assessment of software-based systems

International Nuclear Information System (INIS)

Korhonen, J.; Pulkkinen, U.; Haapanen, P.

1997-01-01

Plant vendors nowadays propose software-based systems even for the most critical safety functions. The reliability estimation of safety critical software-based systems is difficult since the conventional modeling techniques do not necessarily apply to the analysis of these systems, and the quantification seems to be impossible. Due to lack of operational experience and due to the nature of software faults, the conventional reliability estimation methods can not be applied. New methods are therefore needed for the safety assessment of software-based systems. In the research project Programmable automation systems in nuclear power plants (OHA), financed together by the Finnish Centre for Radiation and Nuclear Safety (STUK), the Ministry of Trade and Industry and the Technical Research Centre of Finland (VTT), various safety assessment methods and tools for software based systems are developed and evaluated. This volume in the OHA-report series deals with the statistical reliability assessment of software based systems on the basis of dynamic test results and qualitative evidence from the system design process. Other reports to be published later on in OHA-report series will handle the diversity requirements in safety critical software-based systems, generation of test data from operational profiles and handling of programmable automation in plant PSA-studies. (orig.) (25 refs.)

Reliable and valid assessment of performance in thoracoscopy

DEFF Research Database (Denmark)

Konge, Lars; Lehnert, Per; Hansen, Henrik Jessen

2012-01-01

BACKGROUND: As we move toward competency-based education in medicine, we have lagged in developing competency-based evaluation methods. In the era of minimally invasive surgery, there is a need for a reliable and valid tool dedicated to measure competence in video-assisted thoracoscopic surgery....... The purpose of this study is to create such an assessment tool, and to explore its reliability and validity. METHODS: An expert group of physicians created an assessment tool consisting of 10 items rated on a five-point rating scale. The following factors were included: economy and confidence of movement...

Reliability and risk evaluation of a port oil pipeline transportation system in variable operation conditions

Energy Technology Data Exchange (ETDEWEB)

Soszynska, Joanna, E-mail: joannas@am.gdynia.p [Department of Mathematics, Gdynia Maritime University, ul. Morska 83, 81-225 Gdynia (Poland)

2010-02-15

The semi-Markov model of the system operation processes is proposed and its selected characteristics are determined. A system composed on multi-state components is considered and its reliability and risk characteristics are found. Next, the joint model of the system operation process and the system multi-state reliability is applied to the reliability and risk evaluation of the port oil pipeline transportation system. The pipeline system is described and its operation process unknown parameters are identified on the basis of real statistical data. The mean values of the pipeline system operation process unconditional sojourn times in particular operation states are found and applied to determining this process transient probabilities in these states. The piping different reliability structures in various its operation states are fixed and their conditional reliability functions on the basis of data coming from experts are approximately determined. Finally, after applying earlier estimated transient probabilities and system conditional reliability functions in particular operation states the unconditional reliability function, the mean values and standard deviations of the pipeline lifetimes in particular reliability states, risk function and the moment when the risk exceeds a critical value are found.

Reliability and risk evaluation of a port oil pipeline transportation system in variable operation conditions

International Nuclear Information System (INIS)

Soszynska, Joanna

2010-01-01

The semi-Markov model of the system operation processes is proposed and its selected characteristics are determined. A system composed on multi-state components is considered and its reliability and risk characteristics are found. Next, the joint model of the system operation process and the system multi-state reliability is applied to the reliability and risk evaluation of the port oil pipeline transportation system. The pipeline system is described and its operation process unknown parameters are identified on the basis of real statistical data. The mean values of the pipeline system operation process unconditional sojourn times in particular operation states are found and applied to determining this process transient probabilities in these states. The piping different reliability structures in various its operation states are fixed and their conditional reliability functions on the basis of data coming from experts are approximately determined. Finally, after applying earlier estimated transient probabilities and system conditional reliability functions in particular operation states the unconditional reliability function, the mean values and standard deviations of the pipeline lifetimes in particular reliability states, risk function and the moment when the risk exceeds a critical value are found.

Reliability and validity of the Farsi version of the standardized assessment of personality-abbreviated scale

Directory of Open Access Journals (Sweden)

Maryam Sepehri

2017-06-01

Full Text Available Introduction: A short screening tool for high-risk individuals with personality disorder (PD is useful both for clinicians and researchers. The aim of this study was to assess the validity and reliability of the Farsi version of the Standardized Assessment of Personality-Abbreviated Scale (SAPAS. Methods: The original English version of the SAPAS questionnaire was translated into Farsi, and then, translated back into English by two professionals. A survey was then conducted using the questionnaire on 150 clients of primary health care centers in Tabriz, Iran. A total of 235 medical students were also studied for the reliability assessment of the questionnaire. The SAPAS was compared to the short form of Minnesota Multiphasic Personality Inventory (MMPI. The data analysis was performed using receiver operating characteristic (ROC curve technique, operating characteristic for diagnostic efficacy, Cronbach's alpha, and test-retest for reliability evaluation. Results: We found an area under the curve (AUC of 0.566 [95% confidence intervals (CI: 0.455-0.677]; sensitivity of 0.89 and specificity of 0.26 at the cut-off score of 2 and higher. The total Cronbach's alpha coefficient was 0.38 and Cohen's kappa ranged between 0.5 and 0.8. Conclusion: The current study showed that the Farsi version of the SAPAS was relatively less efficient, in term of validity and reliability, in the screening of PD in the population.

Development of a Standardized Kalamazoo Communication Skills Assessment Tool for Radiologists: Validation, Multisource Reliability, and Lessons Learned.

Science.gov (United States)

Brown, Stephen D; Rider, Elizabeth A; Jamieson, Katherine; Meyer, Elaine C; Callahan, Michael J; DeBenedectis, Carolynn M; Bixby, Sarah D; Walters, Michele; Forman, Sara F; Varrin, Pamela H; Forbes, Peter; Roussin, Christopher J

2017-08-01

The purpose of this study was to develop and test a standardized communication skills assessment instrument for radiology. The Delphi method was used to validate the Kalamazoo Communication Skills Assessment instrument for radiology by revising and achieving consensus on the 43 items of the preexisting instrument among an interdisciplinary team of experts consisting of five radiologists and four nonradiologists (two men, seven women). Reviewers assessed the applicability of the instrument to evaluation of conversations between radiology trainees and trained actors portraying concerned parents in enactments about bad news, radiation risks, and diagnostic errors that were video recorded during a communication workshop. Interrater reliability was assessed by use of the revised instrument to rate a series of enactments between trainees and actors video recorded in a hospital-based simulator center. Eight raters evaluated each of seven different video-recorded interactions between physicians and parent-actors. The final instrument contained 43 items. After three review rounds, 42 of 43 (98%) items had an average rating of relevant or very relevant for bad news conversations. All items were rated as relevant or very relevant for conversations about error disclosure and radiation risk. Reliability and rater agreement measures were moderate. The intraclass correlation coefficient range was 0.07-0.58; mean, 0.30; SD, 0.13; and median, 0.30. The range of weighted kappa values was 0.03-0.47; mean, 0.23; SD, 0.12; and median, 0.22. Ratings varied significantly among conversations (χ 2 6 = 1186; p communication skills assessment instrument is highly relevant for radiology, having moderate interrater reliability. These findings have important implications for assessing the relational competencies of radiology trainees.

Life cycle reliability assessment of new products—A Bayesian model updating approach

International Nuclear Information System (INIS)

Peng, Weiwen; Huang, Hong-Zhong; Li, Yanfeng; Zuo, Ming J.; Xie, Min

2013-01-01

The rapidly increasing pace and continuously evolving reliability requirements of new products have made life cycle reliability assessment of new products an imperative yet difficult work. While much work has been done to separately estimate reliability of new products in specific stages, a gap exists in carrying out life cycle reliability assessment throughout all life cycle stages. We present a Bayesian model updating approach (BMUA) for life cycle reliability assessment of new products. Novel features of this approach are the development of Bayesian information toolkits by separately including “reliability improvement factor” and “information fusion factor”, which allow the integration of subjective information in a specific life cycle stage and the transition of integrated information between adjacent life cycle stages. They lead to the unique characteristics of the BMUA in which information generated throughout life cycle stages are integrated coherently. To illustrate the approach, an application to the life cycle reliability assessment of a newly developed Gantry Machining Center is shown

Reliability and risk treatment centered maintenance

International Nuclear Information System (INIS)

Pexa, Martin; Hladik, Tomas; Ales, Zdenek; Legat, Vaclav; Muller, Miroslav; Valasek, Petr; Havlu, Vit

2014-01-01

We propose a new methodology for application of well-known tools - RCM, RBI and SIF pro - with the aim to treat risks by means of suitable maintenance. The basis of the new methodology is the complex application of all three methods at the same time and not separately as is typical today. The proposed methodology suggests having just one managing team for reliability and risk treatment centred maintenance (RRTCM), employing existing RCM, RBI, and SIFpro tools concurrently. This approach allows for significant reduction of engineering activities' duration. In the proposed methodology these activities are staged into five phases and structured to eliminate all duplication resulting from separate application of the three tools. The newly proposed methodology saves 45% to 50% of the engineering workload and dequate significant financial savings.

Reliability and risk treatment centered maintenance

Energy Technology Data Exchange (ETDEWEB)

Pexa, Martin; Hladik, Tomas; Ales, Zdenek; Legat, Vaclav; Muller, Miroslav; Valasek, Petr [Czech University of Life Sciences Prague, Kamycka (Czech Republic); Havlu, Vit [Unipetrol A. S, Prague (Czech Republic)

2014-10-15

We propose a new methodology for application of well-known tools - RCM, RBI and SIF pro - with the aim to treat risks by means of suitable maintenance. The basis of the new methodology is the complex application of all three methods at the same time and not separately as is typical today. The proposed methodology suggests having just one managing team for reliability and risk treatment centred maintenance (RRTCM), employing existing RCM, RBI, and SIFpro tools concurrently. This approach allows for significant reduction of engineering activities' duration. In the proposed methodology these activities are staged into five phases and structured to eliminate all duplication resulting from separate application of the three tools. The newly proposed methodology saves 45% to 50% of the engineering workload and dequate significant financial savings.

Clinical assessment of dysphagia in neurodegeneration (CADN): development, validity and reliability of a bedside tool for dysphagia assessment.

Science.gov (United States)

Vogel, Adam P; Rommel, Natalie; Sauer, Carina; Horger, Marius; Krumm, Patrick; Himmelbach, Marc; Synofzik, Matthis

2017-06-01

Screening assessments for dysphagia are essential in neurodegenerative disease. Yet there are no purpose-built tools to quantify swallowing deficits at bedside or in clinical trials. A quantifiable, brief, easy to administer assessment that measures the impact of dysphagia and predicts the presence or absence of aspiration is needed. The Clinical Assessment of Dysphagia in Neurodegeneration (CADN) was designed by a multidisciplinary team (neurology, neuropsychology, speech pathology) validated against strict methodological criteria in two neurodegenerative diseases, Parkinson's disease (PD) and degenerative ataxia (DA). CADN comprises two parts, an anamnesis (part one) and consumption (part two). Two-thirds of patients were assessed using reference tests, the SWAL-QOL symptoms subscale (part one) and videofluoroscopic assessment of swallowing (part two). CADN has 11 items and can be administered and scored in an average of 7 min. Test-retest reliability was established using correlation and Bland-Altman plots. 125 patients with a neurodegenerative disease were recruited; 60 PD and 65 DA. Validity was established using ROC graphs and correlations. CADN has sensitivity of 79 and 84% and specificity 71 and 69% for parts one and two, respectively. Significant correlations with disease severity were also observed (p dysphagia symptomatology and risk of aspiration. The CADN is a reliable, valid, brief, quantifiable, and easily deployed assessment of swallowing in neurodegenerative disease. It is thus ideally suited for both clinical bedside assessment and future multicentre clinical trials in neurodegenerative disease.

ASSESSING AND COMBINING RELIABILITY OF PROTEIN INTERACTION SOURCES

Science.gov (United States)

LEACH, SONIA; GABOW, AARON; HUNTER, LAWRENCE; GOLDBERG, DEBRA S.

2008-01-01

Integrating diverse sources of interaction information to create protein networks requires strategies sensitive to differences in accuracy and coverage of each source. Previous integration approaches calculate reliabilities of protein interaction information sources based on congruity to a designated ‘gold standard.’ In this paper, we provide a comparison of the two most popular existing approaches and propose a novel alternative for assessing reliabilities which does not require a gold standard. We identify a new method for combining the resultant reliabilities and compare it against an existing method. Further, we propose an extrinsic approach to evaluation of reliability estimates, considering their influence on the downstream tasks of inferring protein function and learning regulatory networks from expression data. Results using this evaluation method show 1) our method for reliability estimation is an attractive alternative to those requiring a gold standard and 2) the new method for combining reliabilities is less sensitive to noise in reliability assignments than the similar existing technique. PMID:17990508

Reliability and validity of selected measures associated with increased fall risk in females over the age of 45 years with distal radius fracture - A pilot study.

Science.gov (United States)

Mehta, Saurabh P; MacDermid, Joy C; Richardson, Julie; MacIntyre, Norma J; Grewal, Ruby

2015-01-01

Clinical measurement. This study examined test-retest reliability and convergent/divergent construct validity of selected tests and measures that assess balance impairment, fear of falling (FOF), impaired physical activity (PA), and lower extremity muscle strength (LEMS) in females >45 years of age after the distal radius fracture (DRF) population. Twenty one female participants with DRF were assessed on two occasions. Timed Up and Go, Functional Reach, and One Leg Standing tests assessed balance impairment. Shortened Falls Efficacy Scale, Activity-specific Balance Confidence scale, and Fall Risk Perception Questionnaire assessed FOF. International Physical Activity Questionnaire and Rapid Assessment of Physical Activity were administered to assess PA level. Chair stand test and isometric muscle strength testing for hip and knee assessed LEMS. Intraclass correlation coefficients (ICC) examined the test-retest reliability of the measures. Pearson correlation coefficients (r) examined concurrent relationships between the measures. The results demonstrated fair to excellent test-retest reliability (ICC between 0.50 and 0.96) and low to moderate concordance between the measures (low if r ≤ 0.4; moderate if r = 0.4-0.7). The results provide preliminary estimates of test-retest reliability and convergent/divergent construct validity of selected measures associated with increased risk for falling in the females >45 years of age after DRF. Further research directions to advance knowledge regarding fall risk assessment in DRF population have been identified. Copyright © 2015 Hanley & Belfus. Published by Elsevier Inc. All rights reserved.

Prediction of Maintenance Period of Equipment Through Risk Assessment of Thermal Power Plants

Energy Technology Data Exchange (ETDEWEB)

Song, Gee Wook; Kim, Bum Shin; Choi, Woo Song; Park, Myung Soo [KEPCO Research Institute, Daejeon (Korea, Republic of)

2013-10-15

Risk-based inspection (RBI) is a well-known method that is used to optimize inspection activities based on risk analysis in order to identify the high-risk components of major facilities such as power plants. RBI, when implemented and maintained properly, improves plant reliability and safety while reducing unplanned outages and repair costs. Risk is given by the product of the probability of failure (Pof) and the consequence of failure (COF). A semi-quantitative method is generally used for risk assessment. Semi-quantitative risk assessment complements the low accuracy of qualitative risk assessment and the high expense and long calculation time of quantitative risk assessment. The first step of RB I is to identify important failure modes and causes in the equipment. Once these are defined, the Pof and COF can be assessed for each failure. During Pof and COF assessment, an effective inspection method and range can be easily found. In this paper, the calculation of the Pof is improved for accurate risk assessment. A modified semi-quantitative risk assessment was carried out for boiler facilities of thermal power plants, and the next maintenance schedules for the equipment were decided.

Prediction of Maintenance Period of Equipment Through Risk Assessment of Thermal Power Plants

International Nuclear Information System (INIS)

Song, Gee Wook; Kim, Bum Shin; Choi, Woo Song; Park, Myung Soo

2013-01-01

Risk-based inspection (RBI) is a well-known method that is used to optimize inspection activities based on risk analysis in order to identify the high-risk components of major facilities such as power plants. RBI, when implemented and maintained properly, improves plant reliability and safety while reducing unplanned outages and repair costs. Risk is given by the product of the probability of failure (Pof) and the consequence of failure (COF). A semi-quantitative method is generally used for risk assessment. Semi-quantitative risk assessment complements the low accuracy of qualitative risk assessment and the high expense and long calculation time of quantitative risk assessment. The first step of RB I is to identify important failure modes and causes in the equipment. Once these are defined, the Pof and COF can be assessed for each failure. During Pof and COF assessment, an effective inspection method and range can be easily found. In this paper, the calculation of the Pof is improved for accurate risk assessment. A modified semi-quantitative risk assessment was carried out for boiler facilities of thermal power plants, and the next maintenance schedules for the equipment were decided

Taking the Risk Out of Risk Assessment

Science.gov (United States)

2005-01-01

The ability to understand risks and have the right strategies in place when risky events occur is essential in the workplace. More and more organizations are being confronted with concerns over how to measure their risks or what kind of risks they can take when certain events transpire that could have a negative impact. NASA is one organization that faces these challenges on a daily basis, as effective risk management is critical to the success of its missions especially the Space Shuttle missions. On July 29, 1996, former NASA Administrator Daniel Goldin charged NASA s Office of Safety and Mission Assurance with developing a probabilistic risk assessment (PRA) tool to support decisions on the funding of Space Shuttle upgrades. When issuing the directive, Goldin said, "Since I came to NASA [in 1992], we've spent billions of dollars on Shuttle upgrades without knowing how much they improve safety. I want a tool to help base upgrade decisions on risk." Work on the PRA tool began immediately. The resulting prototype, the Quantitative Risk Assessment System (QRAS) Version 1.0, was jointly developed by NASA s Marshall Space Flight Center, its Office of Safety and Mission Assurance, and researchers at the University of Maryland. QRAS software automatically expands the reliability logic models of systems to evaluate the probability of highly detrimental outcomes occurring in complex systems that are subject to potential accident scenarios. Even in its earliest forms, QRAS was used to begin PRA modeling of the Space Shuttle. In parallel, the development of QRAS continued, with the goal of making it a world-class tool, one that was especially suited to NASA s unique needs. From the beginning, an important conceptual goal in the development of QRAS was for it to help bridge the gap between the professional risk analyst and the design engineer. In the past, only the professional risk analyst could perform, modify, use, and perhaps even adequately understand PRA. NASA wanted

Human Reliability Assessments: Using the Past (Shuttle) to Predict the Future (Orion)

Science.gov (United States)

DeMott, Diana L.; Bigler, Mark A.

2017-01-01

NASA (National Aeronautics and Space Administration) Johnson Space Center (JSC) Safety and Mission Assurance (S&MA) uses two human reliability analysis (HRA) methodologies. The first is a simplified method which is based on how much time is available to complete the action, with consideration included for environmental and personal factors that could influence the human's reliability. This method is expected to provide a conservative value or placeholder as a preliminary estimate. This preliminary estimate or screening value is used to determine which placeholder needs a more detailed assessment. The second methodology is used to develop a more detailed human reliability assessment on the performance of critical human actions. This assessment needs to consider more than the time available, this would include factors such as: the importance of the action, the context, environmental factors, potential human stresses, previous experience, training, physical design interfaces, available procedures/checklists and internal human stresses. The more detailed assessment is expected to be more realistic than that based primarily on time available. When performing an HRA on a system or process that has an operational history, we have information specific to the task based on this history and experience. In the case of a Probabilistic Risk Assessment (PRA) that is based on a new design and has no operational history, providing a "reasonable" assessment of potential crew actions becomes more challenging. To determine what is expected of future operational parameters, the experience from individuals who had relevant experience and were familiar with the system and process previously implemented by NASA was used to provide the "best" available data. Personnel from Flight Operations, Flight Directors, Launch Test Directors, Control Room Console Operators, and Astronauts were all interviewed to provide a comprehensive picture of previous NASA operations. Verification of the

Development of a methodology for conducting an integrated HRA/PRA --. Task 1, An assessment of human reliability influences during LP&S conditions PWRs

Energy Technology Data Exchange (ETDEWEB)

Luckas, W.J.; Barriere, M.T.; Brown, W.S. [Brookhaven National Lab., Upton, NY (United States); Wreathall, J. [Wreathall (John) and Co., Dublin, OH (United States); Cooper, S.E. [Science Applications International Corp., McLean, VA (United States)

1993-06-01

During Low Power and Shutdown (LP&S) conditions in a nuclear power plant (i.e., when the reactor is subcritical or at less than 10--15% power), human interactions with the plant`s systems will be more frequent and more direct. Control is typically not mediated by automation, and there are fewer protective systems available. Therefore, an assessment of LP&S related risk should include a greater emphasis on human reliability than such an assessment made for power operation conditions. In order to properly account for the increase in human interaction and thus be able to perform a probabilistic risk assessment (PRA) applicable to operations during LP&S, it is important that a comprehensive human reliability assessment (HRA) methodology be developed and integrated into the LP&S PRA. The tasks comprising the comprehensive HRA methodology development are as follows: (1) identification of the human reliability related influences and associated human actions during LP&S, (2) identification of potentially important LP&S related human actions and appropriate HRA framework and quantification methods, and (3) incorporation and coordination of methodology development with other integrated PRA/HRA efforts. This paper describes the first task, i.e., the assessment of human reliability influences and any associated human actions during LP&S conditions for a pressurized water reactor (PWR).

Interrater reliability of videotaped observational gait-analysis assessments.

Science.gov (United States)

Eastlack, M E; Arvidson, J; Snyder-Mackler, L; Danoff, J V; McGarvey, C L

1991-06-01

The purpose of this study was to determine the interrater reliability of videotaped observational gait-analysis (VOGA) assessments. Fifty-four licensed physical therapists with varying amounts of clinical experience served as raters. Three patients with rheumatoid arthritis who demonstrated an abnormal gait pattern served as subjects for the videotape. The raters analyzed each patient's most severely involved knee during the four subphases of stance for the kinematic variables of knee flexion and genu valgum. Raters were asked to determine whether these variables were inadequate, normal, or excessive. The temporospatial variables analyzed throughout the entire gait cycle were cadence, step length, stride length, stance time, and step width. Generalized kappa coefficients ranged from .11 to .52. Intraclass correlation coefficients (2,1) and (3,1) were slightly higher. Our results indicate that physical therapists' VOGA assessments are only slightly to moderately reliable and that improved interrater reliability of the assessments of physical therapists utilizing this technique is needed. Our data suggest that there is a need for greater standardization of gait-analysis training.

Money laundering: correlation between risk assessment and suspicious transactions

Directory of Open Access Journals (Sweden)

Sonja Cindori

2013-06-01

Full Text Available The risk assessment system was introduced in the Republic of Croatia in 2009, as a result of harmonization with international standards, especially the Directive 2005/60/EC on the prevention of the use of the financial system for the purpose of money laundering and terrorist financing. Risk assessment is an extensive concept which requires not only a legislative framework, but also the application of numerous criteria for its effective implementation in practice. Among these criteria are suspicious transactions, closely related to the assessment of the customer, transaction, product or service.The undeniable contribution of suspicious transactions to the quality of the risk assessment system will be confirmed by a statistical analysis of a number of West and East European countries. A combination of strict, but sufficiently flexible legal provisions governing the system for prevention of money laundering and terrorist financing and a statistical analysis of reported suspicious transactions will lead to conclusions that either support or represent criticism of the efficiency of application of the risk assessment system in practice.The aforementioned statistical analysis will show whether suspicious transactions are a reliable criterion for the risk assessment analysis, and whether they can be considered the only such criterion. There is a possibility that the findings of the analysis will be contradictory to those of some international studies.

A comprehensive approach to benefit-risk assessment in drug development

DEFF Research Database (Denmark)

Sarac, Sinan B; Rasmussen, Christian H; Rasmussen, Morten A.

2012-01-01

Major regulatory agencies, for example, FDA and EMA, have started to request comprehensive benefit-risk analyses of pharmaceutical products prior to approval or labelling expansion. The purpose of this study is to develop a generally applicable and reliable data-driven benefit-risk assessment......) discussion and formulation of an overall conclusion. To reduce the impact of subjective judgements, scores are assigned to each criterion on the basis of objective information (data) wherever possible. The proposed benefit-risk evaluation approach offers comprehensive, data-driven assessments that can...... method, where two or more drugs/doses can be compared. Our aim is to formulate an approach that is simple to apply, allows direct comparison of different types of risks and benefits, and is tailored for application in different disease areas both during clinical development and in the marketing approval...

Fast Reliability Assessing Method for Distribution Network with Distributed Renewable Energy Generation

Science.gov (United States)

Chen, Fan; Huang, Shaoxiong; Ding, Jinjin; Ding, Jinjin; Gao, Bo; Xie, Yuguang; Wang, Xiaoming

2018-01-01

This paper proposes a fast reliability assessing method for distribution grid with distributed renewable energy generation. First, the Weibull distribution and the Beta distribution are used to describe the probability distribution characteristics of wind speed and solar irradiance respectively, and the models of wind farm, solar park and local load are built for reliability assessment. Then based on power system production cost simulation probability discretization and linearization power flow, a optimal power flow objected with minimum cost of conventional power generation is to be resolved. Thus a reliability assessment for distribution grid is implemented fast and accurately. The Loss Of Load Probability (LOLP) and Expected Energy Not Supplied (EENS) are selected as the reliability index, a simulation for IEEE RBTS BUS6 system in MATLAB indicates that the fast reliability assessing method calculates the reliability index much faster with the accuracy ensured when compared with Monte Carlo method.

Folate status in women of reproductive age as basis of neural tube defect risk assessment.

Science.gov (United States)

Bailey, Lynn B; Hausman, Dorothy B

2018-02-01

Reliable folate status data for women of reproductive age (WRA) to assess global risk for neural tube defects (NTDs) are needed. We focus on a recent recommendation by the World Health Organization that a specific "optimal" red blood cell (RBC) folate concentration be used as the sole indicator of NTD risk within a population and discuss how to best apply this guidance to reach the goal of assessing NTD risk globally. We also emphasize the importance of using the microbiologic assay (MBA) as the most reliable assay for obtaining comparable results for RBC folate concentration across time and countries, the need for harmonization of the MBA through use of consistent key reagents and procedures within laboratories, and the requirement to apply assay-matched cutoffs for folate deficiency and insufficiency. To estimate NTD risk globally, the ideal scenario would be to have country-specific population-based surveys of RBC folate in WRA determined utilizing a harmonized MBA, as was done in recent studies in Guatemala and Belize. We conclude with guidance on next steps to best navigate the road map toward the goal of generating reliable folate status data on which to assess NTD risk in WRA in low- and middle-income countries. © 2017 The Authors. Annals of the New York Academy of Sciences published by Wiley Periodicals, Inc. on behalf of New York Academy of Sciences.

Nuclear Computerized Library for Assessing Reactor Reliability (NUCLARR): Data manual. Part 3: Hardware component failure data; Volume 5, Revision 4

International Nuclear Information System (INIS)

Reece, W.J.; Gilbert, B.G.; Richards, R.E.

1994-09-01

This data manual contains a hard copy of the information in the Nuclear Computerized Library for Assessing Reactor Reliability (NUCLARR) Version 3.5 database, which is sponsored by the US Nuclear Regulatory Commission. NUCLARR was designed as a tool for risk analysis. Many of the nuclear reactors in the US and several outside the US are represented in the NUCLARR database. NUCLARR includes both human error probability estimates for workers at the plants and hardware failure data for nuclear reactor equipment. Aggregations of these data yield valuable reliability estimates for probabilistic risk assessments and human reliability analyses. The data manual is organized to permit manual searches of the information if the computerized version is not available. Originally, the manual was published in three parts. In this revision the introductory material located in the original Part 1 has been incorporated into the text of Parts 2 and 3. The user can now find introductory material either in the original Part 1, or in Parts 2 and 3 as revised. Part 2 contains the human error probability data, and Part 3, the hardware component reliability data

Reliable and valid assessment of Lichtenstein hernia repair skills

DEFF Research Database (Denmark)

Carlsen, C G; Lindorff Larsen, Karen; Funch-Jensen, P

2014-01-01

PURPOSE: Lichtenstein hernia repair is a common surgical procedure and one of the first procedures performed by a surgical trainee. However, formal assessment tools developed for this procedure are few and sparsely validated. The aim of this study was to determine the reliability and validity...... of an assessment tool designed to measure surgical skills in Lichtenstein hernia repair. METHODS: Key issues were identified through a focus group interview. On this basis, an assessment tool with eight items was designed. Ten surgeons and surgical trainees were video recorded while performing Lichtenstein hernia...... a significant difference between the three groups which indicates construct validity, p skills can be assessed blindly by a single rater in a reliable and valid fashion with the new procedure-specific assessment tool. We recommend this tool for future assessment...

Transcriptomic resources for environmental risk assessment: a case study in the Venice lagoon

International Nuclear Information System (INIS)

Milan, M.; Pauletto, M.; Boffo, L.; Carrer, C.; Sorrentino, F.; Ferrari, G.; Pavan, L.; Patarnello, T.; Bargelloni, L.

2015-01-01

The development of new resources to evaluate the environmental status is becoming increasingly important representing a key challenge for ocean and coastal management. Recently, the employment of transcriptomics in aquatic toxicology has led to increasing initiatives proposing to integrate eco-toxicogenomics in the evaluation of marine ecosystem health. However, several technical issues need to be addressed before introducing genomics as a reliable tool in regulatory ecotoxicology. The Venice lagoon constitutes an excellent case, in which the assessment of environmental risks derived from the nearby industrial activities represents a crucial task. In this context, the potential role of genomics to assist environmental monitoring was investigated through the definition of reliable gene expression markers associated to chemical contamination in Manila clams, and their subsequent employment for the classification of Venice lagoon areas. Overall, the present study addresses key issues to evaluate the future outlooks of genomics in the environmental monitoring and risk assessment. - Highlights: • Growing need to develop new resources for the evaluation of the environmental status. • Identification of gene expression markers associated to chemical contamination. • Employment of genomics to evaluate the environmental status of Venice lagoon areas. • Hurdles and future outlooks of genomic tools in environmental risk assessment. - Genomics in risk assessment of Venice lagoon

RELIABILITY ASSESSMENT OF ENTROPY METHOD FOR SYSTEM CONSISTED OF IDENTICAL EXPONENTIAL UNITS

Institute of Scientific and Technical Information of China (English)

Sun Youchao; Shi Jun

2004-01-01

The reliability assessment of unit-system near two levels is the most important content in the reliability multi-level synthesis of complex systems. Introducing the information theory into system reliability assessment, using the addible characteristic of information quantity and the principle of equivalence of information quantity, an entropy method of data information conversion is presented for the system consisted of identical exponential units. The basic conversion formulae of entropy method of unit test data are derived based on the principle of information quantity equivalence. The general models of entropy method synthesis assessment for system reliability approximate lower limits are established according to the fundamental principle of the unit reliability assessment. The applications of the entropy method are discussed by way of practical examples. Compared with the traditional methods, the entropy method is found to be valid and practicable and the assessment results are very satisfactory.

Methodology for reliability based condition assessment

International Nuclear Information System (INIS)

Mori, Y.; Ellingwood, B.

1993-08-01

Structures in nuclear power plants may be exposed to aggressive environmental effects that cause their strength to decrease over an extended period of service. A major concern in evaluating the continued service for such structures is to ensure that in their current condition they are able to withstand future extreme load events during the intended service life with a level of reliability sufficient for public safety. This report describes a methodology to facilitate quantitative assessments of current and future structural reliability and performance of structures in nuclear power plants. This methodology takes into account the nature of past and future loads, and randomness in strength and in degradation resulting from environmental factors. An adaptive Monte Carlo simulation procedure is used to evaluate time-dependent system reliability. The time-dependent reliability is sensitive to the time-varying load characteristics and to the choice of initial strength and strength degradation models but not to correlation in component strengths within a system. Inspection/maintenance strategies are identified that minimize the expected future costs of keeping the failure probability of a structure at or below an established target failure probability during its anticipated service period

A task analysis-linked approach for integrating the human factor in reliability assessments of nuclear power plants

International Nuclear Information System (INIS)

Ryan, T.G.

1988-01-01

This paper describes an emerging Task Analysis-Linked Evaluation Technique (TALENT) for assessing the contributions of human error to nuclear power plant systems unreliability and risk. Techniques such as TALENT are emerging as a recognition that human error is a primary contributor to plant safety, however, it has been a peripheral consideration to data in plant reliability evaluations. TALENT also recognizes that involvement of persons with behavioral science expertise is required to support plant reliability and risk analyses. A number of state-of-knowledge human reliability analysis tools are also discussed which support the TALENT process. The core of TALENT is comprised of task, timeline and interface analysis data which provide the technology base for event and fault tree development, serve as criteria for selecting and evaluating performance shaping factors, and which provide a basis for auditing TALENT results. Finally, programs and case studies used to refine the TALENT process are described along with future research needs in the area. (author)

Tutorial on use of intraclass correlation coefficients for assessing intertest reliability and its application in functional near-infrared spectroscopy-based brain imaging.

Science.gov (United States)

Li, Lin; Zeng, Li; Lin, Zi-Jing; Cazzell, Mary; Liu, Hanli

2015-05-01

Test-retest reliability of neuroimaging measurements is an important concern in the investigation of cognitive functions in the human brain. To date, intraclass correlation coefficients (ICCs), originally used in interrater reliability studies in behavioral sciences, have become commonly used metrics in reliability studies on neuroimaging and functional near-infrared spectroscopy (fNIRS). However, as there are six popular forms of ICC, the adequateness of the comprehensive understanding of ICCs will affect how one may appropriately select, use, and interpret ICCs toward a reliability study. We first offer a brief review and tutorial on the statistical rationale of ICCs, including their underlying analysis of variance models and technical definitions, in the context of assessment on intertest reliability. Second, we provide general guidelines on the selection and interpretation of ICCs. Third, we illustrate the proposed approach by using an actual research study to assess interest reliability of fNIRS-based, volumetric diffuse optical tomography of brain activities stimulated by a risk decision-making protocol. Last, special issues that may arise in reliability assessment using ICCs are discussed and solutions are suggested.

Tutorial on use of intraclass correlation coefficients for assessing intertest reliability and its application in functional near-infrared spectroscopy-based brain imaging

Science.gov (United States)

Li, Lin; Zeng, Li; Lin, Zi-Jing; Cazzell, Mary; Liu, Hanli

2015-05-01

Test-retest reliability of neuroimaging measurements is an important concern in the investigation of cognitive functions in the human brain. To date, intraclass correlation coefficients (ICCs), originally used in inter-rater reliability studies in behavioral sciences, have become commonly used metrics in reliability studies on neuroimaging and functional near-infrared spectroscopy (fNIRS). However, as there are six popular forms of ICC, the adequateness of the comprehensive understanding of ICCs will affect how one may appropriately select, use, and interpret ICCs toward a reliability study. We first offer a brief review and tutorial on the statistical rationale of ICCs, including their underlying analysis of variance models and technical definitions, in the context of assessment on intertest reliability. Second, we provide general guidelines on the selection and interpretation of ICCs. Third, we illustrate the proposed approach by using an actual research study to assess intertest reliability of fNIRS-based, volumetric diffuse optical tomography of brain activities stimulated by a risk decision-making protocol. Last, special issues that may arise in reliability assessment using ICCs are discussed and solutions are suggested.

A computational Bayesian approach to dependency assessment in system reliability

International Nuclear Information System (INIS)

Yontay, Petek; Pan, Rong

2016-01-01

Due to the increasing complexity of engineered products, it is of great importance to develop a tool to assess reliability dependencies among components and systems under the uncertainty of system reliability structure. In this paper, a Bayesian network approach is proposed for evaluating the conditional probability of failure within a complex system, using a multilevel system configuration. Coupling with Bayesian inference, the posterior distributions of these conditional probabilities can be estimated by combining failure information and expert opinions at both system and component levels. Three data scenarios are considered in this study, and they demonstrate that, with the quantification of the stochastic relationship of reliability within a system, the dependency structure in system reliability can be gradually revealed by the data collected at different system levels. - Highlights: • A Bayesian network representation of system reliability is presented. • Bayesian inference methods for assessing dependencies in system reliability are developed. • Complete and incomplete data scenarios are discussed. • The proposed approach is able to integrate reliability information from multiple sources at multiple levels of the system.

Nuclear computerized library for assessing reactor reliability (NUCLARR): User's guide: Part 3, NUCLARR system description

International Nuclear Information System (INIS)

Gilmore, W.E.; Gentillon, C.D.; Gertman, D.I.; Beers, G.H.; Galyean, W.J.; Gilbert, B.G.

1988-06-01

The Nuclear Computerized Library for Assessing Reactor Reliability (NUCLARR) is an automated data base management system for processing and storing human error probability and hardware component failure data. The NUCLARR system software resides on an IBM (or compatible) personal micro-computer. NUCLARR can be used by the end user to furnish data inputs for both human and hardware reliability analysis in support of a variety of risk assessment activities. The NUCLARR system is documented in a five-volume series of reports. Volume IV of this series is the User's Guide for operating the NUCLARR software and is presented in three parts. This document, Part 3: NUCLARR System Description, provides an in-depth discussion of the design characteristics and special features of the NUCLARR software. Part 3 also presents the organization of the data base structures and techniques used to manipulate the data

Nuclear computerized library for assessing reactor reliability (NUCLARR): Part 2, Guide to operations: User's guide

International Nuclear Information System (INIS)

Gilmore, W.E.; Gentillon, C.D.; Gertman, D.I.; Beers, G.H.; Galyean, W.J.; Gilbert, B.G.

1988-06-01

The Nuclear Computerized Library for Assessing Reactor Reliability (NUCLARR) is an automated data base management system for processing and storing human error probability and hardware component failure data. The NUCLARR system software resides on an IBM (or compatible) personal micro-computer. NUCLARR can be used by the end user to furnish data inputs for both human and hardware reliability analysis in support of a variety of risk assessment activities. The NUCLARR system is documented in a five-volume series of reports. Volume IV of this series is the User's Guide for operating the NUCLARR software and is presented in three parts. This volume, Part 2: Guide to Operations, contains the instructions and basic procedures for using the NUCLARR software. Part 2 provides guidance and information for getting started, performing the desired functions, and making the most efficient use of the system's features

Reliable and valid assessment of Lichtenstein hernia repair skills.

Science.gov (United States)

Carlsen, C G; Lindorff-Larsen, K; Funch-Jensen, P; Lund, L; Charles, P; Konge, L

2014-08-01

Lichtenstein hernia repair is a common surgical procedure and one of the first procedures performed by a surgical trainee. However, formal assessment tools developed for this procedure are few and sparsely validated. The aim of this study was to determine the reliability and validity of an assessment tool designed to measure surgical skills in Lichtenstein hernia repair. Key issues were identified through a focus group interview. On this basis, an assessment tool with eight items was designed. Ten surgeons and surgical trainees were video recorded while performing Lichtenstein hernia repair, (four experts, three intermediates, and three novices). The videos were blindly and individually assessed by three raters (surgical consultants) using the assessment tool. Based on these assessments, validity and reliability were explored. The internal consistency of the items was high (Cronbach's alpha = 0.97). The inter-rater reliability was very good with an intra-class correlation coefficient (ICC) = 0.93. Generalizability analysis showed a coefficient above 0.8 even with one rater. The coefficient improved to 0.92 if three raters were used. One-way analysis of variance found a significant difference between the three groups which indicates construct validity, p fashion with the new procedure-specific assessment tool. We recommend this tool for future assessment of trainees performing Lichtenstein hernia repair to ensure that the objectives of competency-based surgical training are met.

The effect of introducing increased-reliability-risk electronic components into 3rd generation telecommunications systems

International Nuclear Information System (INIS)

Salmela, Olli

2005-01-01

In this paper, the dependability of 3rd generation telecommunications network systems is studied. Special attention is paid to a case where increased-reliability-risk electronic components are introduced to the system. The paper consists of three parts: First, the reliability data of four electronic components is considered. This includes statistical analysis of the reliability test data, thermo-mechanical finite element analysis of the printed wiring board structures, and based on those, a field reliability estimate of the components is constructed. Second, the component level reliability data is introduced into the network element reliability analysis. This is accomplished by using a reliability block diagram technique and Monte Carlo simulation of the network element. The end result of the second part is a reliability estimate of the network element with and without the high-risk component. Third, the whole 3rd generation network having multiple network elements is analyzed. In this part, the criticality of introducing high-risk electronic components into a 3rd generation telecommunications network is considered

The effect of introducing increased-reliability-risk electronic components into 3rd generation telecommunications systems

Energy Technology Data Exchange (ETDEWEB)

Salmela, Olli [Nokia Networks, P.O. Box 301, 00045 Nokia Group (Finland)]. E-mail: olli.salmela@nokia.com

2005-08-01

In this paper, the dependability of 3rd generation telecommunications network systems is studied. Special attention is paid to a case where increased-reliability-risk electronic components are introduced to the system. The paper consists of three parts: First, the reliability data of four electronic components is considered. This includes statistical analysis of the reliability test data, thermo-mechanical finite element analysis of the printed wiring board structures, and based on those, a field reliability estimate of the components is constructed. Second, the component level reliability data is introduced into the network element reliability analysis. This is accomplished by using a reliability block diagram technique and Monte Carlo simulation of the network element. The end result of the second part is a reliability estimate of the network element with and without the high-risk component. Third, the whole 3rd generation network having multiple network elements is analyzed. In this part, the criticality of introducing high-risk electronic components into a 3rd generation telecommunications network is considered.

Reliability of a semi-quantitative method for dermal exposure assessment (DREAM)

NARCIS (Netherlands)

Wendel de Joode, B. van; Hemmen, J.J. van; Meijster, T.; Major, V.; London, L.; Kromhout, H.

2005-01-01

Valid and reliable semi-quantitative dermal exposure assessment methods for epidemiological research and for occupational hygiene practice, applicable for different chemical agents, are practically nonexistent. The aim of this study was to assess the reliability of a recently developed

Reporting and evaluation criteria as means towards a transparent use of ecotoxicity data for environmental risk assessment of pharmaceuticals

International Nuclear Information System (INIS)

Agerstrand, M.; Kuester, A.; Bachmann, J.; Breitholtz, M.; Ebert, I.; Rechenberg, B.; Ruden, C.

2011-01-01

Ecotoxicity data with high reliability and relevance are needed to guarantee the scientific quality of environmental risk assessments of pharmaceuticals. The main advantages of a more structured approach to data evaluation include increased transparency and predictability of the risk assessment process, and the possibility to use non-standard data. In this collaboration, between the research project MistraPharma and the German Federal Environment Agency, a new set of reporting and evaluation criteria is presented and discussed. The new criteria are based on the approaches in the literature and the OECD reporting requirements, and have been further developed to include both reliability and relevance of test data. Intended users are risk assessors and researchers performing ecotoxicological experiments, but the criteria can also be used for education purposes and in the peer-review process for scientific papers. This approach intends to bridge the gap between the regulator and the scientist's needs and way of work. - Highlights: → A structured approach to data evaluation increases the transparency and predictability of the risk assessment process. → A structured approach to data reporting opens up for use of data from the open scientific literature in risk assessments. → Both relevance and reliability aspects are included in the reporting and evaluation criteria. → The criteria can be used by risk assessors, by researchers, for education purposes and in the peer-review process. - The need for reporting and evaluation criteria towards a transparent and reliable use of ecotoxicity data.

A systematic review of balance and fall risk assessments with mobile phone technology.

Science.gov (United States)

Roeing, Kathleen L; Hsieh, Katherine L; Sosnoff, Jacob J

2017-11-01

Falls are a major health concern for older adults. Preventative measures can help reduce the incidence and severity of falls. Methods for assessing balance and fall risk factors are necessary to effectively implement preventative measures. Research groups are currently developing mobile applications to enable seniors, caregivers, and clinicians to monitor balance and fall risk. The following systematic review assesses the current state of mobile health apps for testing balance as a fall risk factor. Thirteen studies were identified and included in the review and analyzed based on study design, population, sample size, measures of balance, main outcome measures, and evaluation of validity and reliability. All studies successfully tested their applications, but only 38% evaluated the validity, and 23% evaluated the reliability of their applications. Of those, all applications were found to accurately and reliably measure balance on select variables. Four of the 13 studies included special populations groups. Out of the 13 studies, 12 reported clinicians as their intended user and seven reported seniors as their intended user. Further research should examine the validity of mobile health applications as well as report on the application's usability. Copyright © 2017 Elsevier B.V. All rights reserved.

Human Reliability in Probabilistic Safety Assessments; Fiabilidad Humana en los Analisis Probabilisticos de Seguridad

Energy Technology Data Exchange (ETDEWEB)

Nunez Mendez, J

1989-07-01

Nowadays a growing interest in environmental aspects is detected in our country. It implies an assessment of the risk involved in the industrial processes and installations in order to determine if those are into the acceptable limits. In these safety assessments, among which PSA (Probabilistic Safety Assessments), can be pointed out the role played by the human being in the system is one of the more relevant subjects (This relevance has been demonstrated in the accidents happened) . However, in Spain there aren't manuals specifically dedicated to asses the human contribution to risk in the frame of PSAs. This report aims to improve this situation providing: a) a theoretical background to help the reader in the understanding of the nature of the human error, b) a quid to carry out a Human Reliability Analysis and c) a selected overview of the techniques and methodologies currently applied in this area. (Author) 20 refs.

Human Reliability in Probabilistic Safety Assessments; Fiabilidad Humana en los Analisis Probabilisticos de Seguridad

Energy Technology Data Exchange (ETDEWEB)

Nunez Mendez, J.

1989-07-01

Nowadays a growing interest in environmental aspects is detected in our country. It implies an assessment of the risk involved in the industrial processes and installations in order to determine if those are into the acceptable limits. In these safety assessments, among which PSA (Probabilistic Safety Assessments), can be pointed out the role played by the human being in the system is one of the more relevant subjects (This relevance has been demonstrated in the accidents happened) . However, in Spain there aren't manuals specifically dedicated to asses the human contribution to risk in the frame of PSAs. This report aims to improve this situation providing: a) a theoretical background to help the reader in the understanding of the nature of the human error, b) a quid to carry out a Human Reliability Analysis and c) a selected overview of the techniques and methodologies currently applied in this area. (Author) 20 refs.

Assessment of modern methods of human factor reliability analysis in PSA studies

International Nuclear Information System (INIS)

Holy, J.

2001-12-01

The report is structured as follows: Classical terms and objects (Probabilistic safety assessment as a framework for human reliability assessment; Human failure within the PSA model; Basic types of operator failure modelled in a PSA study and analyzed by HRA methods; Qualitative analysis of human reliability; Quantitative analysis of human reliability used; Process of analysis of nuclear reactor operator reliability in a PSA study); New terms and objects (Analysis of dependences; Errors of omission; Errors of commission; Error forcing context); and Overview and brief assessment of human reliability analysis (Basic characteristics of the methods; Assets and drawbacks of the use of each of HRA method; History and prospects of the use of the methods). (P.A.)

Overview of DOE-NE Proliferation and Terrorism Risk Assessment

International Nuclear Information System (INIS)

Sadasivan, Pratap

2012-01-01

Research objectives are: (1) Develop technologies and other solutions that can improve the reliability, sustain the safety, and extend the life of current reactors; (2) Develop improvements in the affordability of new reactors to enable nuclear energy; (3) Develop Sustainable Nuclear Fuel Cycles; and (4) Understand and minimize the risks of nuclear proliferation and terrorism. The goal is to enable the use of risk information to inform NE R and D program planning. The PTRA program supports DOE-NE's goal of using risk information to inform R and D program planning. The FY12 PTRA program is focused on terrorism risk. The program includes a mix of innovative methods that support the general practice of risk assessments, and selected applications.

Feasibility and reliability of a newly developed antenatal risk score card in routine care

NARCIS (Netherlands)

E. Birnie; E.A.P. Steegers; Drs. H.W. Torij; M.J. Veen; J. Poeran; G.J. Bonsel

2015-01-01

A population-based cross-sectional study (feasibility) and a cohort study (inter-rater reliability) to study in routine care the feasibility and inter-rater reliability of the Rotterdam Reproductive Risk Reduction risk score card (R4U), a new semi-quantitative score card for use during the antenatal

Risk Assessment Overview

Science.gov (United States)

Prassinos, Peter G.; Lyver, John W., IV; Bui, Chinh T.

2011-01-01

Risk assessment is used in many industries to identify and manage risks. Initially developed for use on aeronautical and nuclear systems, risk assessment has been applied to transportation, chemical, computer, financial, and security systems among others. It is used to gain an understanding of the weaknesses or vulnerabilities in a system so modification can be made to increase operability, efficiency, and safety and to reduce failure and down-time. Risk assessment results are primary inputs to risk-informed decision making; where risk information including uncertainty is used along with other pertinent information to assist management in the decision-making process. Therefore, to be useful, a risk assessment must be directed at specific objectives. As the world embraces the globalization of trade and manufacturing, understanding the associated risk become important to decision making. Applying risk assessment techniques to a global system of development, manufacturing, and transportation can provide insight into how the system can fail, the likelihood of system failure and the consequences of system failure. The risk assessment can identify those elements that contribute most to risk and identify measures to prevent and mitigate failures, disruptions, and damaging outcomes. In addition, risk associated with public and environment impact can be identified. The risk insights gained can be applied to making decisions concerning suitable development and manufacturing locations, supply chains, and transportation strategies. While risk assessment has been mostly applied to mechanical and electrical systems, the concepts and techniques can be applied across other systems and activities. This paper provides a basic overview of the development of a risk assessment.

Introduction to risk assessment

International Nuclear Information System (INIS)

Raina, V.M.

2002-01-01

This paper gives an introduction to risk assessment. It discusses the basic concepts of risk assessment, nuclear risk assessment process and products, the role of risk assessment products in nuclear safety assurance, the relationship between risk assessment and other safety analysis and risk assessment and safe operating envelope

Uncertainty propagation and sensitivity analysis in system reliability assessment via unscented transformation

International Nuclear Information System (INIS)

Rocco Sanseverino, Claudio M.; Ramirez-Marquez, José Emmanuel

2014-01-01

The reliability of a system, notwithstanding it intended function, can be significantly affected by the uncertainty in the reliability estimate of the components that define the system. This paper implements the Unscented Transformation to quantify the effects of the uncertainty of component reliability through two approaches. The first approach is based on the concept of uncertainty propagation, which is the assessment of the effect that the variability of the component reliabilities produces on the variance of the system reliability. This assessment based on UT has been previously considered in the literature but only for system represented through series/parallel configuration. In this paper the assessment is extended to systems whose reliability cannot be represented through analytical expressions and require, for example, Monte Carlo Simulation. The second approach consists on the evaluation of the importance of components, i.e., the evaluation of the components that most contribute to the variance of the system reliability. An extension of the UT is proposed to evaluate the so called “main effects” of each component, as well to assess high order component interaction. Several examples with excellent results illustrate the proposed approach. - Highlights: • Simulation based approach for computing reliability estimates. • Computation of reliability variance via 2n+1 points. • Immediate computation of component importance. • Application to network systems

Simulation Approach to Mission Risk and Reliability Analysis, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — It is proposed to develop and demonstrate an integrated total-system risk and reliability analysis approach that is based on dynamic, probabilistic simulation. This...

Plant lifetime reliability and risk: Addressing today's strategies for making tomorrow's decisions

International Nuclear Information System (INIS)

Boccio, J.L.

1986-01-01

This paper presents an overview of some of the research projects, conducted for the US Nuclear Regulatory Commission (NRC) that deal with the question: How can an acceptable level of risk of a nuclear power plant be maintained throughout its design life? With a viewpoint that life extension planning for a plant can be viewed as a long-range, strategic maintenance program, the products of this research are discussed from the perspective of being elements that can tie day-to-day, plant operational tactical decisions on component/system reliability with long-range strategic maintenance goals. A common factor in addressing issues associated with design life and life extension is the issue of component aging and the reliability implications of aging. A time-dependent reliability model is described which contains some of the requisite ingredients and is built on a framework from which the component aging/component reliability issue can be addressed. By way of select examples, the additional work needed to further address plant lifetime reliability and risk is indicated

Cumulative Risk Assessment (CRA): transforming the way we assess health risks.

Science.gov (United States)

Williams, Pamela R D; Dotson, G Scott; Maier, Andrew

2012-10-16

Human health risk assessments continue to evolve and now focus on the need for cumulative risk assessment (CRA). CRA involves assessing the combined risk from coexposure to multiple chemical and nonchemical stressors for varying health effects. CRAs are broader in scope than traditional chemical risk assessments because they allow for a more comprehensive evaluation of the interaction between different stressors and their combined impact on human health. Future directions of CRA include greater emphasis on local-level community-based assessments; integrating environmental, occupational, community, and individual risk factors; and identifying and implementing common frameworks and risk metrics for incorporating multiple stressors.

Review of Reliability Assessment of Westinghouse SSPS Using SPC by WEC

International Nuclear Information System (INIS)

Kang, H. T.; Chung, H. Y.

2007-01-01

Westinghouse Electric Company (WEC) has accomplished the reliability assessment of Westinghouse Solid State Protection System (SSPS) in KORI no. 2, 3, 4, and YGN no. 1, 2. In their studies, it is reported that creating a cost-effective plan for improving the reliability of the SSPS and at KORI no. 2, 3 and 4, and YGN no. 1, 2 should be needed while reducing their maintenance cost. In this paper, we reviewed the reliability assessment of Westinghouse SSPS analyzed in two performance standards, availability, and the maintenance expense using Statistic Process Control (SPC). As a result, it is concluded all plants have several failures reported but no effect on the system's availability, and the maintenance expense analysis did not reduce the current maintenance expense by 30%. Therefore, overall review for the reliability assessment is that a new strategy for cost-effective plan and/or upgrade approach for improving the reliability of the aging Westinghouse SSPS should be needed

Translation, reliability, and clinical utility of the Melbourne Assessment 2.

Science.gov (United States)

Gerber, Corinna N; Plebani, Anael; Labruyère, Rob

2017-10-12

The aims were to (i) provide a German translation of the Melbourne Assessment 2 (MA2), a quantitative test to measure unilateral upper limb function in children with neurological disabilities and (ii) to evaluate its reliability and aspects of clinical utility. After its translation into German and approval of the back translation by the original authors, the MA2 was performed and videotaped twice with 30 children with neuromotor disorders. For each participant, two raters scored the video of the first test for inter-rater reliability. To determine test-retest reliability, one rater additionally scored the video of the second test while the other rater repeated the scoring of the first video to evaluate intra-rater reliability. Time needed for rater training, test administration, and scoring was recorded. The four subscale scores showed excellent intra-, inter-rater, and test-retest reliability with intraclass correlation coefficients of 0.90-1.00 (95%-confidence intervals 0.78-1.00). Score items revealed substantial to almost perfect intra-rater reliability (weighted kappa k w  = 0.66-1.00) for the more affected side. Score item inter-rater and test-retest reliability of the same extremity were, with one exception, moderate to almost perfect (k w  = 0.42-0.97; k w  = 0.40-0.89). Furthermore, the MA2 was feasible and acceptable for patients and clinicians. The MA2 showed excellent subscale and moderate to almost perfect score item reliability. Implications for Rehabilitation There is a lack of high-quality studies about psychometric properties of upper limb measurement tools in the neuropediatric population. The Melbourne Assessment 2 is a promising tool for reliable measurement of unilateral upper limb movement quality in the neuropediatric population. The Melbourne Assessment 2 is acceptable and practicable to therapists and patients for routine use in clinical care.

Space Shuttle Probabilistic Risk Assessment (SPRA) Iteration 3.2

Science.gov (United States)

Boyer, Roger L.

2010-01-01

The Shuttle is a very reliable vehicle in comparison with other launch systems. Much of the risk posed by Shuttle operations is related to fundamental aspects of the spacecraft design and the environments in which it operates. It is unlikely that significant design improvements can be implemented to address these risks prior to the end of the Shuttle program. The model will continue to be used to identify possible emerging risk drivers and allow management to make risk-informed decisions on future missions. Potential uses of the SPRA in the future include: - Calculate risk impact of various mission contingencies (e.g. late inspection, crew rescue, etc.). - Assessing the risk impact of various trade studies (e.g. flow control valves). - Support risk analysis on mission specific events, such as in flight anomalies. - Serve as a guiding star and data source for future NASA programs.

Nuclear Computerized Library for Assessing Reactor Reliability (NUCLARR): Data manual. Part 2: Human error probability (HEP) data; Volume 5, Revision 4

Energy Technology Data Exchange (ETDEWEB)

Reece, W.J.; Gilbert, B.G.; Richards, R.E. [EG and G Idaho, Inc., Idaho Falls, ID (United States)

1994-09-01

This data manual contains a hard copy of the information in the Nuclear Computerized Library for Assessing Reactor Reliability (NUCLARR) Version 3.5 database, which is sponsored by the US Nuclear Regulatory Commission. NUCLARR was designed as a tool for risk analysis. Many of the nuclear reactors in the US and several outside the US are represented in the NUCLARR database. NUCLARR includes both human error probability estimates for workers at the plants and hardware failure data for nuclear reactor equipment. Aggregations of these data yield valuable reliability estimates for probabilistic risk assessments and human reliability analyses. The data manual is organized to permit manual searches of the information if the computerized version is not available. Originally, the manual was published in three parts. In this revision the introductory material located in the original Part 1 has been incorporated into the text of Parts 2 and 3. The user can now find introductory material either in the original Part 1, or in Parts 2 and 3 as revised. Part 2 contains the human error probability data, and Part 3, the hardware component reliability data.

Nuclear Computerized Library for Assessing Reactor Reliability (NUCLARR): Data manual. Part 2: Human error probability (HEP) data; Volume 5, Revision 4

International Nuclear Information System (INIS)

Reece, W.J.; Gilbert, B.G.; Richards, R.E.

1994-09-01

This data manual contains a hard copy of the information in the Nuclear Computerized Library for Assessing Reactor Reliability (NUCLARR) Version 3.5 database, which is sponsored by the US Nuclear Regulatory Commission. NUCLARR was designed as a tool for risk analysis. Many of the nuclear reactors in the US and several outside the US are represented in the NUCLARR database. NUCLARR includes both human error probability estimates for workers at the plants and hardware failure data for nuclear reactor equipment. Aggregations of these data yield valuable reliability estimates for probabilistic risk assessments and human reliability analyses. The data manual is organized to permit manual searches of the information if the computerized version is not available. Originally, the manual was published in three parts. In this revision the introductory material located in the original Part 1 has been incorporated into the text of Parts 2 and 3. The user can now find introductory material either in the original Part 1, or in Parts 2 and 3 as revised. Part 2 contains the human error probability data, and Part 3, the hardware component reliability data

Nuclear Computerized Library for Assessing Reactor Reliability (NUCLARR): Data manual, Part 2: Human Error Probability (HEP) Data. Volume 5, Revision 4

International Nuclear Information System (INIS)

Reece, W.J.; Gilbert, B.G.; Richards, R.E.

1994-09-01

This data manual contains a hard copy of the information in the Nuclear Computerized Library for Assessing Reactor Reliability (NUCLARR) Version 3.5 database, which is sponsored by the US Nuclear Regulatory Commission. NUCLARR was designed as a tool for risk analysis. Many of the nuclear reactors in the US and several outside the US are represented in the NUCLARR database. NUCLARR includes both human error probability estimates for workers at the plants and hardware failure data for nuclear reactor equipment. Aggregations of these data yield valuable reliability estimates for probabilistic risk assessments and human reliability analyses. The data manual is organized to permit manual searches of the information if the computerized version is not available. Originally, the manual was published in three parts. In this revision the introductory material located in the original Part 1 has been incorporated into the text of Parts 2 and 3. The user can now find introductory material either in the original Part 1, or in Parts 2 and 3 as revised. Part 2 contains the human error probability data, and Part 3, the hardware component reliability data

Assessment of the Reliability of Concrete Bridges

DEFF Research Database (Denmark)

Middleton, C. R.; Thoft-Christensen, Palle

Although there has been a considerable amount of research into different aspects of concrete bridge reliability, it has still not been widely adopted in professional practice other than in the development and calibration of codes. This situation appears to be changing as there has been a signific......Although there has been a considerable amount of research into different aspects of concrete bridge reliability, it has still not been widely adopted in professional practice other than in the development and calibration of codes. This situation appears to be changing as there has been...... adopted to assist in achieving this goal. Rather than review the specific research on this subject this paper examines a number of key issues related to the practical application of reliability analysis to the assessment of concrete bridges....

Clinical assessment of scapular positioning in musicians: an intertester reliability study.

Science.gov (United States)

Struyf, Filip; Nijs, Jo; De Coninck, Kris; Giunta, Marco; Mottram, Sarah; Meeusen, Romain

2009-01-01

The reliability of the measurement of the distance between the posterior border of the acromion and the wall and the reliability of the modified lateral scapular slide test have not been studied. Overall, the reliability of the clinical tools used to assess scapular positioning has not been studied in musicians. To examine the intertester reliability of scapular observation and 2 clinical tests for the assessment of scapular positioning in musicians. Intertester reliability study. University research laboratory. Thirty healthy student musicians at a single university. Two assessors performed a standardized observation protocol, the measurement of the distance between the posterior border of the acromion and the wall, and the modified lateral scapular slide test. Each assessor was blinded to the other's findings. The intertester reliability coefficients (kappa) for the observation in relaxed position, during unloaded movement, and during loaded movement were 0.41, 0.63, and 0.36, respectively. The kappa values for the observation of tilting and winging at rest were 0.48 and 0.42, respectively; during unloaded movement, the kappa values were 0.52 and 0.78, respectively; and with a 1-kg load, the kappa values were 0.24 and 0.50, respectively. The intraclass correlation coefficient (ICC) of the measurement of the acromial distance was 0.72 in relaxed position and 0.75 with the participant actively retracting both shoulders. The ICCs for the modified lateral scapular slide test varied between 0.63 and 0.58. Our results demonstrated that the modified lateral scapular slide test was not a reliable tool to assess scapular positioning in these participants. Our data indicated that scapular observation in the relaxed position and during unloaded abduction in the frontal plane was a reliable assessment tool. The reliability of the measurement of the distance between the posterior border of the acromion and the wall in healthy musicians was moderate.

Historical Relationship Between Performance Assessment for Radioactive Waste Disposal and Other Types of Risk Assessment in the United States

Energy Technology Data Exchange (ETDEWEB)

RECHARD,ROBERT P.

2000-07-14

This paper describes the evolution of the process for assessing the hazards of a geologic disposal system for radioactive waste and, similarly, nuclear power reactors, and the relationship of this process with other assessments of risk, particularly assessments of hazards from manufactured carcinogenic chemicals during use and disposal. This perspective reviews the common history of scientific concepts for risk assessment developed to the 1950s. Computational tools and techniques developed in the late 1950s and early 1960s to analyze the reliability of nuclear weapon delivery systems were adopted in the early 1970s for probabilistic risk assessment of nuclear power reactors, a technology for which behavior was unknown. In turn, these analyses became an important foundation for performance assessment of nuclear waste disposal in the late 1970s. The evaluation of risk to human health and the environment from chemical hazards is built upon methods for assessing the dose response of radionuclides in the 1950s. Despite a shared background, however, societal events, often in the form of legislation, have affected the development path for risk assessment for human health, producing dissimilarities between these risk assessments and those for nuclear facilities. An important difference is the regulator's interest in accounting for uncertainty and the tools used to evaluate it.

Historical Relationship Between Performance Assessment for Radioactive Waste Disposal and Other Types of Risk Assessment in the United States

International Nuclear Information System (INIS)

Rechard, Robert P.

2000-01-01

This paper describes the evolution of the process for assessing the hazards of a geologic disposal system for radioactive waste and, similarly, nuclear power reactors, and the relationship of this process with other assessments of risk, particularly assessments of hazards from manufactured carcinogenic chemicals during use and disposal. This perspective reviews the common history of scientific concepts for risk assessment developed to the 1950s. Computational tools and techniques developed in the late 1950s and early 1960s to analyze the reliability of nuclear weapon delivery systems were adopted in the early 1970s for probabilistic risk assessment of nuclear power reactors, a technology for which behavior was unknown. In turn, these analyses became an important foundation for performance assessment of nuclear waste disposal in the late 1970s. The evaluation of risk to human health and the environment from chemical hazards is built upon methods for assessing the dose response of radionuclides in the 1950s. Despite a shared background, however, societal events, often in the form of legislation, have affected the development path for risk assessment for human health, producing dissimilarities between these risk assessments and those for nuclear facilities. An important difference is the regulator's interest in accounting for uncertainty and the tools used to evaluate it

Estimation of Uncertainty in Risk Assessment of Hydrogen Applications

DEFF Research Database (Denmark)

Markert, Frank; Krymsky, V.; Kozine, Igor

2011-01-01

Hydrogen technologies such as hydrogen fuelled vehicles and refuelling stations are being tested in practice in a number of projects (e.g. HyFleet-Cute and Whistler project) giving valuable information on the reliability and maintenance requirements. In order to establish refuelling stations the ...... probability and the NUSAP concept to quantify uncertainties of new not fully qualified hydrogen technologies and implications to risk management.......Hydrogen technologies such as hydrogen fuelled vehicles and refuelling stations are being tested in practice in a number of projects (e.g. HyFleet-Cute and Whistler project) giving valuable information on the reliability and maintenance requirements. In order to establish refuelling stations...... the permitting authorities request qualitative and quantitative risk assessments (QRA) to show the safety and acceptability in terms of failure frequencies and respective consequences. For new technologies not all statistical data might be established or are available in good quality causing assumptions...

Reliable and Valid Assessment of Point-of-care Ultrasonography

DEFF Research Database (Denmark)

Todsen, Tobias; Tolsgaard, Martin Grønnebæk; Olsen, Beth Härstedt

2015-01-01

physicians' OSAUS scores with diagnostic accuracy. RESULTS: The generalizability coefficient was high (0.81) and a D-study demonstrated that 1 assessor and 5 cases would result in similar reliability. The construct validity of the OSAUS scale was supported by a significant difference in the mean scores......OBJECTIVE: To explore the reliability and validity of the Objective Structured Assessment of Ultrasound Skills (OSAUS) scale for point-of-care ultrasonography (POC US) performance. BACKGROUND: POC US is increasingly used by clinicians and is an essential part of the management of acute surgical...... conditions. However, the quality of performance is highly operator-dependent. Therefore, reliable and valid assessment of trainees' ultrasonography competence is needed to ensure patient safety. METHODS: Twenty-four physicians, representing novices, intermediates, and experts in POC US, scanned 4 different...

Feasibility assessment of a risk-based approach to technical specifications

International Nuclear Information System (INIS)

Atefi, B.; Gallagher, D.W.

1991-05-01

To assess the potential use of risk and reliability techniques for improving the effectiveness of the technical specifications to control plant operational risk, the Technical Specifications Branch of the Nuclear Regulatory Commission initiated an effort to identify and evaluate alternative risk-based approaches that could bring greater risk perspective to these requirements. In the first phase four alternative approaches were identified and their characteristics were analyzed. Among these, the risk-based approach to technical specifications is the most promising approach for controlling plant operational risk using technical specifications. The second phase of the study concentrated on detailed characteristics of the real time risk-based approach. It is concluded that a real time risk-based approach to technical specifications has the potential to improve both plant safety and availability. 33 figs., 5 figs., 6 tabs

Validity and reliability of self-reported diabetes in the Atherosclerosis Risk in Communities Study.

Science.gov (United States)

Schneider, Andrea L C; Pankow, James S; Heiss, Gerardo; Selvin, Elizabeth

2012-10-15

The objective of this study was to assess the validity of prevalent and incident self-reported diabetes compared with multiple reference definitions and to assess the reliability (repeatability) of a self-reported diagnosis of diabetes. Data from 10,321 participants in the Atherosclerosis Risk in Communities (ARIC) Study who attended visit 4 (1996-1998) were analyzed. Prevalent self-reported diabetes was compared with reference definitions defined by fasting glucose and medication use obtained at visit 4. Incident self-reported diabetes was assessed during annual follow-up telephone calls and was compared with reference definitions defined by fasting glucose, hemoglobin A1c, and medication use obtained during an in-person visit attended by a subsample of participants (n = 1,738) in 2004-2005. The sensitivity of prevalent self-reported diabetes ranged from 58.5% to 70.8%, and specificity ranged from 95.6% to 96.8%, depending on the reference definition. Similarly, the sensitivity of incident self-reported diabetes ranged from 55.9% to 80.4%, and specificity ranged from 84.5% to 90.6%. Percent positive agreement of self-reported diabetes during 9 years of repeat assessments ranged from 92.7% to 95.4%. Both prevalent self-reported diabetes and incident self-reported diabetes were 84%-97% specific and 55%-80% sensitive as compared with reference definitions using glucose and medication criteria. Self-reported diabetes was >92% reliable over time.

Risk assessment of storm surge disaster based on numerical models and remote sensing

Science.gov (United States)

Liu, Qingrong; Ruan, Chengqing; Zhong, Shan; Li, Jian; Yin, Zhonghui; Lian, Xihu

2018-06-01

Storm surge is one of the most serious ocean disasters in the world. Risk assessment of storm surge disaster for coastal areas has important implications for planning economic development and reducing disaster losses. Based on risk assessment theory, this paper uses coastal hydrological observations, a numerical storm surge model and multi-source remote sensing data, proposes methods for valuing hazard and vulnerability for storm surge and builds a storm surge risk assessment model. Storm surges in different recurrence periods are simulated in numerical models and the flooding areas and depth are calculated, which are used for assessing the hazard of storm surge; remote sensing data and GIS technology are used for extraction of coastal key objects and classification of coastal land use are identified, which is used for vulnerability assessment of storm surge disaster. The storm surge risk assessment model is applied for a typical coastal city, and the result shows the reliability and validity of the risk assessment model. The building and application of storm surge risk assessment model provides some basis reference for the city development plan and strengthens disaster prevention and mitigation.

How reliable are Functional Movement Screening scores? A systematic review of rater reliability.

Science.gov (United States)

Moran, Robert W; Schneiders, Anthony G; Major, Katherine M; Sullivan, S John

2016-05-01

Several physical assessment protocols to identify intrinsic risk factors for injury aetiology related to movement quality have been described. The Functional Movement Screen (FMS) is a standardised, field-expedient test battery intended to assess movement quality and has been used clinically in preparticipation screening and in sports injury research. To critically appraise and summarise research investigating the reliability of scores obtained using the FMS battery. Systematic literature review. Systematic search of Google Scholar, Scopus (including ScienceDirect and PubMed), EBSCO (including Academic Search Complete, AMED, CINAHL, Health Source: Nursing/Academic Edition), MEDLINE and SPORTDiscus. Studies meeting eligibility criteria were assessed by 2 reviewers for risk of bias using the Quality Appraisal of Reliability Studies checklist. Overall quality of evidence was determined using van Tulder's levels of evidence approach. 12 studies were appraised. Overall, there was a 'moderate' level of evidence in favour of 'acceptable' (intraclass correlation coefficient ≥0.6) inter-rater and intra-rater reliability for composite scores derived from live scoring. For inter-rater reliability of composite scores derived from video recordings there was 'conflicting' evidence, and 'limited' evidence for intra-rater reliability. For inter-rater reliability based on live scoring of individual subtests there was 'moderate' evidence of 'acceptable' reliability (κ≥0.4) for 4 subtests (Deep Squat, Shoulder Mobility, Active Straight-leg Raise, Trunk Stability Push-up) and 'conflicting' evidence for the remaining 3 (Hurdle Step, In-line Lunge, Rotary Stability). This review found 'moderate' evidence that raters can achieve acceptable levels of inter-rater and intra-rater reliability of composite FMS scores when using live ratings. Overall, there were few high-quality studies, and the quality of several studies was impacted by poor study reporting particularly in relation to

Assessing the Impact of Imperfect Diagnosis on Service Reliability

DEFF Research Database (Denmark)

Grønbæk, Lars Jesper; Schwefel, Hans-Peter; Kjærgaard, Jens Kristian

2010-01-01

, representative diagnosis performance metrics have been defined and their closed-form solutions obtained for the Markov model. These equations enable model parameterization from traces of implemented diagnosis components. The diagnosis model has been integrated in a reliability model assessing the impact...... of the diagnosis functions for the studied reliability problem. In a simulation study we finally analyze trade-off properties of diagnosis heuristics from literature, map them to the analytic Markov model, and investigate its suitability for service reliability optimization....

Uses of human reliability analysis probabilistic risk assessment results to resolve personnel performance issues that could affect safety

International Nuclear Information System (INIS)

O'Brien, J.N.; Spettell, C.M.

1985-10-01

This report is the first in a series which documents research aimed at improving the usefulness of Probabilistic Risk Assessment (PRA) results in addressing human risk issues. This first report describes the results of an assessment of how well currently available PRA data addresses human risk issues of current concern to NRC. Findings indicate that PRA data could be far more useful in addressing human risk issues with modification of the development process and documentation structure of PRAs. In addition, information from non-PRA sources could be integrated with PRA data to address many other issues. 12 tabs

Operational risk assessment.

Science.gov (United States)

McKim, Vicky L

2017-06-01

In the world of risk management, which encompasses the business continuity disciplines, many types of risk require evaluation. Financial risk is most often the primary focus, followed by product and market risks. Another critical area, which typically lacks a thorough review or may be overlooked, is operational risk. This category encompasses many risk exposure types including those around building structures and systems, environmental issues, nature, neighbours, clients, regulatory compliance, network, data security and so on. At times, insurance carriers will assess internal hazards, but seldom do these assessments include more than a cursory look at other types of operational risk. In heavily regulated environments, risk assessments are required but may not always include thorough assessments of operational exposures. Vulnerabilities may linger or go unnoticed, only to become the catalyst for a business disruption at a later time, some of which are so severe that business recovery becomes nearly impossible. Businesses may suffer loss of clients as the result of a prolonged disruption of services. Comprehensive operational risk assessments can assist in identifying such vulnerabilities, exposures and threats so that the risk can be minimised or removed. This paper lays out how an assessment of this type can be successfully conducted.

Bayesian methods in reliability

Science.gov (United States)

Sander, P.; Badoux, R.

1991-11-01

The present proceedings from a course on Bayesian methods in reliability encompasses Bayesian statistical methods and their computational implementation, models for analyzing censored data from nonrepairable systems, the traits of repairable systems and growth models, the use of expert judgment, and a review of the problem of forecasting software reliability. Specific issues addressed include the use of Bayesian methods to estimate the leak rate of a gas pipeline, approximate analyses under great prior uncertainty, reliability estimation techniques, and a nonhomogeneous Poisson process. Also addressed are the calibration sets and seed variables of expert judgment systems for risk assessment, experimental illustrations of the use of expert judgment for reliability testing, and analyses of the predictive quality of software-reliability growth models such as the Weibull order statistics.

Translation, cross-cultural adaptation to Brazilian- Portuguese and reliability analysis of the instrument Rapid Entire Body Assessment-REBA

Directory of Open Access Journals (Sweden)

Andressa M. Lamarão

2014-06-01

Full Text Available Background: Observational instruments, such as the Rapid Entire Body Assessment, quickly assess biomechanical risks present in the workplace. However, in order to use these instruments, it is necessary to conduct the translational/cross-cultural adaptation of the instrument and test its measurement properties. Objectives: To perform the translation and the cross-cultural adaptation to Brazilian-Portuguese and test the reliability of the REBA instrument. Method: The procedures of translation and cross-cultural adaptation to Brazilian-Portuguese were conducted following proposed guidelines that involved translation, synthesis of translations, back translation, committee review and testing of the pre-final version. In addition, reliability and the intra- and inter-rater percent agreement were obtained with the Linear Weighted Kappa Coefficient that was associated with the 95% Confidence Interval and the cross tabulation 2×2. Results : The procedures for translation and adaptation were adequate and the necessary adjustments were conducted on the instrument. The intra- and inter-rater reliability showed values of 0.104 to 0.504, respectively, ranging from very poor to moderate. The percentage agreement values ranged from 5.66% to 69.81%. The percentage agreement was closer to 100% at the item 'upper arm' (69.81% for the Intra-rater 1 and at the items 'legs' and 'upper arm' for the Intra-rater 2 (62.26%. Conclusions: The processes of translation and cross-cultural adaptation were conducted on the REBA instrument and the Brazilian version of the instrument was obtained. However, despite the reliability of the tests used to correct the translated and adapted version, the reliability values are unacceptable according to the guidelines standard, indicating that the reliability must be re-evaluated. Therefore, caution in the interpretation of the biomechanical risks measured by this instrument should be taken.

Translation, cross-cultural adaptation to Brazilian- Portuguese and reliability analysis of the instrument Rapid Entire Body Assessment-REBA

Science.gov (United States)

Lamarão, Andressa M.; Costa, Lucíola C. M.; Comper, Maria L. C.; Padula, Rosimeire S.

2014-01-01

Background: Observational instruments, such as the Rapid Entire Body Assessment, quickly assess biomechanical risks present in the workplace. However, in order to use these instruments, it is necessary to conduct the translational/cross-cultural adaptation of the instrument and test its measurement properties. Objectives: To perform the translation and the cross-cultural adaptation to Brazilian-Portuguese and test the reliability of the REBA instrument. Method: The procedures of translation and cross-cultural adaptation to Brazilian-Portuguese were conducted following proposed guidelines that involved translation, synthesis of translations, back translation, committee review and testing of the pre-final version. In addition, reliability and the intra- and inter-rater percent agreement were obtained with the Linear Weighted Kappa Coefficient that was associated with the 95% Confidence Interval and the cross tabulation 2×2. Results : The procedures for translation and adaptation were adequate and the necessary adjustments were conducted on the instrument. The intra- and inter-rater reliability showed values of 0.104 to 0.504, respectively, ranging from very poor to moderate. The percentage agreement values ranged from 5.66% to 69.81%. The percentage agreement was closer to 100% at the item 'upper arm' (69.81%) for the Intra-rater 1 and at the items 'legs' and 'upper arm' for the Intra-rater 2 (62.26%). Conclusions: The processes of translation and cross-cultural adaptation were conducted on the REBA instrument and the Brazilian version of the instrument was obtained. However, despite the reliability of the tests used to correct the translated and adapted version, the reliability values are unacceptable according to the guidelines standard, indicating that the reliability must be re-evaluated. Therefore, caution in the interpretation of the biomechanical risks measured by this instrument should be taken. PMID:25003273

Optimal Bi-Objective Redundancy Allocation for Systems Reliability and Risk Management.

Science.gov (United States)

Govindan, Kannan; Jafarian, Ahmad; Azbari, Mostafa E; Choi, Tsan-Ming

2016-08-01

In the big data era, systems reliability is critical to effective systems risk management. In this paper, a novel multiobjective approach, with hybridization of a known algorithm called NSGA-II and an adaptive population-based simulated annealing (APBSA) method is developed to solve the systems reliability optimization problems. In the first step, to create a good algorithm, we use a coevolutionary strategy. Since the proposed algorithm is very sensitive to parameter values, the response surface method is employed to estimate the appropriate parameters of the algorithm. Moreover, to examine the performance of our proposed approach, several test problems are generated, and the proposed hybrid algorithm and other commonly known approaches (i.e., MOGA, NRGA, and NSGA-II) are compared with respect to four performance measures: 1) mean ideal distance; 2) diversification metric; 3) percentage of domination; and 4) data envelopment analysis. The computational studies have shown that the proposed algorithm is an effective approach for systems reliability and risk management.

The Monte Carlo Simulation Method for System Reliability and Risk Analysis

CERN Document Server

Zio, Enrico

2013-01-01

Monte Carlo simulation is one of the best tools for performing realistic analysis of complex systems as it allows most of the limiting assumptions on system behavior to be relaxed. The Monte Carlo Simulation Method for System Reliability and Risk Analysis comprehensively illustrates the Monte Carlo simulation method and its application to reliability and system engineering. Readers are given a sound understanding of the fundamentals of Monte Carlo sampling and simulation and its application for realistic system modeling.   Whilst many of the topics rely on a high-level understanding of calculus, probability and statistics, simple academic examples will be provided in support to the explanation of the theoretical foundations to facilitate comprehension of the subject matter. Case studies will be introduced to provide the practical value of the most advanced techniques.   This detailed approach makes The Monte Carlo Simulation Method for System Reliability and Risk Analysis a key reference for senior undergra...

Probabilistic risk assessment methodology

International Nuclear Information System (INIS)

Shinaishin, M.A.

1988-06-01

The objective of this work is to provide the tools necessary for clear identification of: the purpose of a Probabilistic Risk Study, the bounds and depth of the study, the proper modeling techniques to be used, the failure modes contributing to the analysis, the classical and baysian approaches for manipulating data necessary for quantification, ways for treating uncertainties, and available computer codes that may be used in performing such probabilistic analysis. In addition, it provides the means for measuring the importance of a safety feature to maintaining a level of risk at a Nuclear Power Plant and the worth of optimizing a safety system in risk reduction. In applying these techniques so that they accommodate our national resources and needs it was felt that emphasis should be put on the system reliability analysis level of PRA. Objectives of such studies could include: comparing systems' designs of the various vendors in the bedding stage, and performing grid reliability and human performance analysis using national specific data. (author)

Probabilistic risk assessment methodology

Energy Technology Data Exchange (ETDEWEB)

Shinaishin, M A

1988-06-15

The objective of this work is to provide the tools necessary for clear identification of: the purpose of a Probabilistic Risk Study, the bounds and depth of the study, the proper modeling techniques to be used, the failure modes contributing to the analysis, the classical and baysian approaches for manipulating data necessary for quantification, ways for treating uncertainties, and available computer codes that may be used in performing such probabilistic analysis. In addition, it provides the means for measuring the importance of a safety feature to maintaining a level of risk at a Nuclear Power Plant and the worth of optimizing a safety system in risk reduction. In applying these techniques so that they accommodate our national resources and needs it was felt that emphasis should be put on the system reliability analysis level of PRA. Objectives of such studies could include: comparing systems' designs of the various vendors in the bedding stage, and performing grid reliability and human performance analysis using national specific data. (author)

A Bayesian belief nets based quantitative software reliability assessment for PSA: COTS case study

International Nuclear Information System (INIS)

Eom, H. S.; Sung, T. Y.; Jeong, H. S.; Park, J. H.; Kang, H. G.; Lee, K. Y.; Park, J. K

2002-03-01

Current reliability assessments of safety critical software embedded in the digital systems in nuclear power plants are based on the rule-based qualitative assessment methods. Then recently practical needs require the quantitative features of software reliability for Probabilistic Safety Assessment (PSA) that is one of important methods being used in assessing the whole safety of nuclear power plant. But conventional quantitative software reliability assessment methods are not enough to get the necessary results in assessing the safety critical software used in nuclear power plants. Thus, current reliability assessment methods for these digital systems exclude the software part or use arbitrary values for the software reliability in the assessment. This reports discusses a Bayesian Belief Nets (BBN) based quantification method that models current qualitative software assessment in formal way and produces quantitative results required for PSA. Commercial Off-The-Shelf (COTS) software dedication process that KAERI developed was applied to the discussed BBN based method for evaluating the plausibility of the proposed method in PSA

Tailoring a Human Reliability Analysis to Your Industry Needs

Science.gov (United States)

DeMott, D. L.

2016-01-01

Companies at risk of accidents caused by human error that result in catastrophic consequences include: airline industry mishaps, medical malpractice, medication mistakes, aerospace failures, major oil spills, transportation mishaps, power production failures and manufacturing facility incidents. Human Reliability Assessment (HRA) is used to analyze the inherent risk of human behavior or actions introducing errors into the operation of a system or process. These assessments can be used to identify where errors are most likely to arise and the potential risks involved if they do occur. Using the basic concepts of HRA, an evolving group of methodologies are used to meet various industry needs. Determining which methodology or combination of techniques will provide a quality human reliability assessment is a key element to developing effective strategies for understanding and dealing with risks caused by human errors. There are a number of concerns and difficulties in "tailoring" a Human Reliability Assessment (HRA) for different industries. Although a variety of HRA methodologies are available to analyze human error events, determining the most appropriate tools to provide the most useful results can depend on industry specific cultures and requirements. Methodology selection may be based on a variety of factors that include: 1) how people act and react in different industries, 2) expectations based on industry standards, 3) factors that influence how the human errors could occur such as tasks, tools, environment, workplace, support, training and procedure, 4) type and availability of data, 5) how the industry views risk & reliability, and 6) types of emergencies, contingencies and routine tasks. Other considerations for methodology selection should be based on what information is needed from the assessment. If the principal concern is determination of the primary risk factors contributing to the potential human error, a more detailed analysis method may be employed

Reliability and Availability of Cloud Computing

CERN Document Server

Bauer, Eric

2012-01-01

A holistic approach to service reliability and availability of cloud computing Reliability and Availability of Cloud Computing provides IS/IT system and solution architects, developers, and engineers with the knowledge needed to assess the impact of virtualization and cloud computing on service reliability and availability. It reveals how to select the most appropriate design for reliability diligence to assure that user expectations are met. Organized in three parts (basics, risk analysis, and recommendations), this resource is accessible to readers of diverse backgrounds and experience le

A Valid and Reliable Tool to Assess Nursing Students` Clinical Performance

OpenAIRE

Mehrnoosh Pazargadi; Tahereh Ashktorab; Sharareh Khosravi; Hamid Alavi majd

2013-01-01

Background: The necessity of a valid and reliable assessment tool is one of the most repeated issues in nursing students` clinical evaluation. But it is believed that present tools are not mostly valid and can not assess students` performance properly.Objectives: This study was conducted to design a valid and reliable assessment tool for evaluating nursing students` performance in clinical education.Methods: In this methodological study considering nursing students` performance definition; th...

Reliability and Validity of the Greek Migraine Disability Assessment (MIDAS) Questionnaire.

Science.gov (United States)

Oikonomidi, Theodora; Vikelis, Michail; Artemiadis, Artemios; Chrousos, George P; Darviri, Christina

2018-03-01

The Migraine Disability Assessment (MIDAS) Questionnaire is a reliable and valid instrument for migraine-related disability. Such a tool is needed to quantify migraine-related disability in the Greek population. This validation study aims to assess the test-retest reliability, internal consistency, item discriminant and convergent validity of the Greek translation of the MIDAS. Adults diagnosed with migraine completed the MIDAS Questionnaire on two occasions 3 weeks apart to assess reliability, and completed the RAND-36 to assess validity. Participants (n = 152) had a median MIDAS score of 24 and mostly severe disability (58% were grade IV). The test-retest reliability analysis (N = 59) revealed excellent reliability for the total score. Internal consistency was α = 0.71 for initial and α = 0.82 for retest completion. For item discriminant validity, the correlations between each question and the total score were significant, with high correlations for questions 2-5 (range 0.67 ≤ r ≤ 0.79; p MIDAS score tended to have better wellbeing. Psychometric properties are comparable with those of other published validation studies of the MIDAS and the original. Findings on question 1 show that missing work/school days may be closely related with increased affect issues. The Greek version of the MIDAS Questionnaire has good reliability and validity. This study allowed for cross-cultural comparability of research findings.

Approaches of data combining for reliability assessments with taking into account the priority of data application

International Nuclear Information System (INIS)

Zelenyj, O.V.; Pecheritsa, A.V.

2004-01-01

Based upon the available experience on assessments of risk from Ukrainian NPP's operational events as well as on results of State review of PSA studies for pilot units it should be noted that historical information on domestic NPP's operation is not always available or used properly under implementation of mentioned activities. The several approaches for combining of available generic and specific information for reliability parameters assessment (taking into account the priority of data application) are briefly described in the article along with some recommendations how to apply those approaches

76 FR 10583 - Priorities for Addressing Risks to the Reliability of the Bulk-Power System; Notice Establishing...

Science.gov (United States)

2011-02-25

... Addressing Risks to the Reliability of the Bulk- Power System; Notice Establishing Date for Comments On... regarding priorities for addressing risks to the reliability of the Bulk-Power System, as previously... Bulk-Power System, 76 FR 2369 (January 13, 2011), as supplemented by the Reliability Technical...

Development and evaluation of the McKnight Risk Factor Survey for assessing potential risk and protective factors for disordered eating in preadolescent and adolescent girls.

Science.gov (United States)

Shisslak, C M; Renger, R; Sharpe, T; Crago, M; McKnight, K M; Gray, N; Bryson, S; Estes, L S; Parnaby, O G; Killen, J; Taylor, C B

1999-03-01

To describe the development, test-retest reliability, internal consistency, and convergent validity of the McKnight Risk Factor Survey-III (MRFS-III). The MRFS-III was designed to assess a number of potential risk and protective factors for the development of disordered eating in preadolescent and adolescent girls. Several versions of the MRFS were pilot tested before the MRFS-III was administered to a sample of 651 4th through 12th- grade girls to establish its psychometric properties. Most of the test-retest reliability coefficients of individual items on the MRFS-III were r > .40. Alpha coefficients for each risk and protective factor domain on the MRFS-III were also computed. The majority of these coefficients were r > .60. High convergent validity coefficients were obtained for specific items on the MRFS-III and measures of self-esteem (Rosenberg Self-Esteem Scale) and weight concerns (Weight Concerns Scale). The test-retest reliability, internal consistency, and convergent validity of the MRFS-III suggest that it is a useful new instrument to assess potential risk and protective factors for the development of disordered eating in preadolescent and adolescent girls.

Integrated Reliability and Risk Analysis System (IRRAS), Version 2.5: Reference manual

International Nuclear Information System (INIS)

Russell, K.D.; McKay, M.K.; Sattison, M.B.; Skinner, N.L.; Wood, S.T.; Rasmuson, D.M.

1991-03-01

The Integrated Reliability and Risk Analysis System (IRRAS) is a state-of-the-art, microcomputer-based probabilistic risk assessment (PRA) model development and analysis tool to address key nuclear plant safety issues. IRRAS is an integrated software tool that gives the user the ability to create and analyze fault trees and accident sequences using a microcomputer. This program provides functions that range from graphical fault tree construction to cut set generation and quantification. Version 1.0 of the IRRAS program was released in February of 1987. Since that time, many user comments and enhancements have been incorporated into the program providing a much more powerful and user-friendly system. This version has been designated IRRAS 2.5 and is the subject of this Reference Manual. Version 2.5 of IRRAS provides the same capabilities as Version 1.0 and adds a relational data base facility for managing the data, improved functionality, and improved algorithm performance. 7 refs., 348 figs

Analyzing the Risk of Fire in a Hospital Complex by “Fire Risk Assessment Method for Engineering”(FRAME

Directory of Open Access Journals (Sweden)

Sarsangi V.* MSc,

2016-08-01

Full Text Available Aims The occurrence of fire in residential buildings, commercial complexes and large and small industries cause physical, environmental and financial damages to many different communities. Fire safety in hospitals is sensitive and it is believed that the society takes the responsibility to care sick people. The goal of this study was to use Fire Risk Assessment Method for Engineering (FRAME in a hospital complex environment and assess the level of fire risks. Materials & Methods This descriptive study was conducted in Kashan Shahid Beheshti hospital in 2013. The FRAME is designed based on the empirical and scientific knowledge and experiment and have acceptable reliability for assessing the building fire risk. Excel software was used to calculate the risk level and finally fire risk (R was calculated separately for different units. Findings Calculated Rs were less than 1for health, autoclave, office of nursing and infection control units. R1s were greater than 1 for all units. R2s were less than 1 for office of nursing and infection control units. Conclusion FRAME is an acceptable tool for assessing the risk of fire in buildings and the fire risk is high in Shahid Beheshti Hospital Complex of Kashan and damages can be intolerable in the case of fire.

An Integrative Review of Pediatric Fall Risk Assessment Tools.

Science.gov (United States)

DiGerolamo, Kimberly; Davis, Katherine Finn

Patient fall prevention begins with accurate risk assessment. However, sustained improvements in prevention and quality of care include use of validated fall risk assessment tools (FRATs). The goal of FRATs is to identify patients at highest risk. Adult FRATs are often borrowed from to create tools for pediatric patients. Though factors associated with pediatric falls in the hospital setting are similar to those in adults, such as mobility, medication use, and cognitive impairment, adult FRATs and the factors associated with them do not adequately assess risk in children. Articles were limited to English language, ages 0-21years, and publish date 2006-2015. The search yielded 22 articles. Ten were excluded as the population was primarily adult or lacked discussion of a FRAT. Critical appraisal and findings were synthesized using the Johns Hopkins Nursing evidence appraisal system. Twelve articles relevant to fall prevention in the pediatric hospital setting that discussed fall risk assessment and use of a FRAT were reviewed. Comparison between and accuracy of FRATs is challenged when different classifications, definitions, risk stratification, and inclusion criteria are used. Though there are several pediatric FRATs published in the literature, none have been found to be reliable and valid across institutions and diverse populations. This integrative review highlights the importance of choosing a FRAT based on an institution's identified risk factors and validating the tool for one's own patient population as well as using the tool in conjunction with nursing clinical judgment to guide interventions. Copyright © 2017 Elsevier Inc. All rights reserved.

Use of limited data to construct Bayesian networks for probabilistic risk assessment.

Energy Technology Data Exchange (ETDEWEB)

Groth, Katrina M.; Swiler, Laura Painton

2013-03-01

Probabilistic Risk Assessment (PRA) is a fundamental part of safety/quality assurance for nuclear power and nuclear weapons. Traditional PRA very effectively models complex hardware system risks using binary probabilistic models. However, traditional PRA models are not flexible enough to accommodate non-binary soft-causal factors, such as digital instrumentation&control, passive components, aging, common cause failure, and human errors. Bayesian Networks offer the opportunity to incorporate these risks into the PRA framework. This report describes the results of an early career LDRD project titled %E2%80%9CUse of Limited Data to Construct Bayesian Networks for Probabilistic Risk Assessment%E2%80%9D. The goal of the work was to establish the capability to develop Bayesian Networks from sparse data, and to demonstrate this capability by producing a data-informed Bayesian Network for use in Human Reliability Analysis (HRA) as part of nuclear power plant Probabilistic Risk Assessment (PRA). This report summarizes the research goal and major products of the research.

Reliability of Lactation Assessment Tools Applied to Overweight and Obese Women.

Science.gov (United States)

Chapman, Donna J; Doughty, Katherine; Mullin, Elizabeth M; Pérez-Escamilla, Rafael

2016-05-01

The interrater reliability of lactation assessment tools has not been evaluated in overweight/obese women. This study aimed to compare the interrater reliability of 4 lactation assessment tools in this population. A convenience sample of 45 women (body mass index > 27.0) was videotaped while breastfeeding (twice daily on days 2, 4, and 7 postpartum). Three International Board Certified Lactation Consultants independently rated each videotaped session using 4 tools (Infant Breastfeeding Assessment Tool [IBFAT], modified LATCH [mLATCH], modified Via Christi [mVC], and Riordan's Tool [RT]). For each day and tool, we evaluated interrater reliability with 1-way repeated-measures analyses of variance, intraclass correlation coefficients (ICCs), and percentage absolute agreement between raters. Analyses of variance showed significant differences between raters' scores on day 2 (all scales) and day 7 (RT). Intraclass correlation coefficient values reflected good (mLATCH) to excellent reliability (IBFAT, mVC, and RT) on days 2 and 7. All day 4 ICCs reflected good reliability. The ICC for mLATCH was significantly lower than all others on day 2 and was significantly lower than IBFAT (day 7). Percentage absolute interrater agreement for scale components ranged from 31% (day 2: observable swallowing, RT) to 92% (day 7: IBFAT, fixing; and mVC, latch time). Swallowing scores on all scales had the lowest levels of interrater agreement (31%-64%). We demonstrated differences in the interrater reliability of 4 lactation assessment tools when applied to overweight/obese women, with the lowest values observed on day 4. Swallowing assessment was particularly unreliable. Researchers and clinicians using these scales should be aware of the differences in their psychometric behavior. © The Author(s) 2015.

Probabilistic risk assessment and its role in plant modifications

International Nuclear Information System (INIS)

Diederich, A.R.; McElroy, W.F.

1986-01-01

Electric Utilities today have a tool available to improve management's ability to evaluate nuclear power plant modifications (MODS). Probabilistic Risk Assessment (PRA), is a tool of choice since it can be applied to a specific situation such as MOD request review, bringing the perspectives of reliability, financial risk and consequences to the public in addition to the more rigid requirements like those associated with Quality Assurance or licensing criteria. The techniques used in the PRA process revolve about the creation and manipulation of Fault Trees and Event Trees, which are used to quantify the event sequences and reliability of plant systems in a logical framework. It is through these methods that chains of sequences, or events, are understood. The degree to which plant systems are modelled in the PRA can vary depending on resources and purpose. Philadelphia Elecrtric Company's PRA modelled ten (10) major systems but this number may increase during the application and updating process

Roads at risk - the impact of debris flows on road network reliability and vulnerability in southern Norway

Science.gov (United States)

Meyer, Nele Kristin; Schwanghart, Wolfgang; Korup, Oliver

2014-05-01

Norwegian's road network is frequently affected by debris flows. Both damage repair and traffic interruption generate high economic losses and necessitate a rigorous assessment of where losses are expected to be high and where preventive measures should be focused on. In recent studies, we have developed susceptibility and trigger probability maps that serve as input into a hazard calculation at the scale of first-order watersheds. Here we combine these results with graph theory to assess the impact of debris flows on the road network of southern Norway. Susceptibility and trigger probability are aggregated for individual road sections to form a reliability index that relates to the failure probability of a link that connects two network vertices, e.g., road junctions. We define link vulnerability as a function of traffic volume and additional link failure distance. Additional link failure distance is the extra length of the alternative path connecting the two associated link vertices in case the network link fails and is calculated by a shortest-path algorithm. The product of network reliability and vulnerability indices represent the risk index. High risk indices identify critical links for the Norwegian road network and are investigated in more detail. Scenarios demonstrating the impact of single or multiple debris flow events are run for the most important routes between seven large cities in southern Norway. First results show that the reliability of the road network is lowest in the central and north-western part of the study area. Road network vulnerability is highest in the mountainous regions in central southern Norway where the road density is low and in the vicinity of cities where the traffic volume is large. The scenarios indicate that city connections that have their shortest path via routes crossing the central part of the study area have the highest risk of route failure.

Probabilistic assessment of roadway departure risk in a curve

Science.gov (United States)

Rey, G.; Clair, D.; Fogli, M.; Bernardin, F.

2011-10-01

Roadway departure while cornering constitutes a major part of car accidents and casualties in France. Even though drastic policy about overspeeding contributes to reduce accidents, there obviously exist other factors. This article presents the construction of a probabilistic strategy for the roadway departure risk assessment. A specific vehicle dynamic model is developed in which some parameters are modelled by random variables. These parameters are deduced from a sensitivity analysis to ensure an efficient representation of the inherent uncertainties of the system. Then, structural reliability methods are employed to assess the roadway departure risk in function of the initial conditions measured at the entrance of the curve. This study is conducted within the French national road safety project SARI that aims to implement a warning systems alerting the driver in case of dangerous situation.

Validity and Reliability of the Questionnaire for Assessing Women’s Reproductive History in Azar Cohort Study

Directory of Open Access Journals (Sweden)

Mohammad Zakaria Pezeshki

2017-06-01

Full Text Available This study was done to evaluate the validity and reliability of women’s reproductive history questionnaire which will be used in Azar Cohort study; a cohort that is conducted by Tabriz University of Medical Science in Shabestar county for identifying risk factors of no communicable diseases. Content and face validity were evaluated by ten experts in the field and quantified as content validity index (CVI and content validity ratio (CVR. To assess the reliability, using test-retest approach, kappa statistic was calculated for categorical variables and intra-class correlation coefficient (ICC was used for the quantitative items. The calculated CVI and CVR were 0.91and 0.94, respectively. Reliability for all items was high. The ICC was 0.99 and kappa statistic was equal to 1. The final version of questionnaire was redesigned in 26 items with 7 subscales.

Hepatitis Risk Assessment

Science.gov (United States)

... please visit this page: About CDC.gov . Hepatitis Risk Assessment Recommend on Facebook Tweet Share Compartir Viral Hepatitis. Are you at risk? Take this 5 minute Hepatitis Risk Assessment developed ...

Nuclear Computerized Library for Assessing Reactor Risk (NUCLARR)

International Nuclear Information System (INIS)

Gilmore, W.E.; Blackman, H.S.; Ryan, T.G.

1986-01-01

The Nuclear Computerized Library for Assessing Reactor Risk (NUCLARR) program is a multiyear effort sponsored by the NRC and is being conducted at the Idaho National Engineering Laboratory (INEL). The goal of this program is to establish and operate computerized data base management tools for the human reliability data bank specification developed by Comer and Donovan. The NRC and the risk analysis community recognized that implementing a fully functional library would not be feasible, or practical, without the aid of computerized tools for management and manipulation of its data sources. The end users of the NUCLARR can be classified into three categories according to specific needs. The first category is those users interested in reviewing individual data sources for a given situation. The second category of users selects multiple data sources for a specific case, summarizing the information, and performing comparative studies. The last category of users interfaces the NUCLARR with other programming applications, such as other data banks, and simulation models of risk assessment. Project status is provided in the paper

Assessment of risks of loose landslide deposits formed by the 2008 Wenchuan earthquake

Science.gov (United States)

Zhang, S.; Zhang, L. M.; Peng, M.; Zhang, L. L.; Zhao, H. F.; Chen, H. X.

2012-05-01

A Geographic Information System (GIS)-based quantitative risk assessment methodology was adopted to evaluate the risks of loose deposits formed by the 2008 Wenchuan earthquake along a highway near the epicenter. A total of 305 loose deposits with a total volume of 4.0 × 107 m3 has been identified. A physical model was used to determine the failure probability of these loose deposits under six rainfall scenarios, assuming the loose deposits as infinite slopes. The calculated probability of rain-induced slope failures is verified by the recorded landslides at the same site during a storm in 2010. Seventy-nine out of the 112 rain-induced loose deposit failures are predicted by the reliability analysis, with an accuracy of 71%. The results of reliability analysis and information on the consequence of these rain-induced landslides enable the estimation of the annual societal and individual risks of the loose deposits. Under the rainfall scenarios of 30 mm/12 h and 70 mm/12 h, the estimated annual societal risks reach 8.8 and 7.5, respectively, and the individual risks reach 0.05 and 0.04, respectively, which are very high compared with present risk acceptance criteria. The preliminary assessment provides a benchmark for studying the long-term risks of these loose deposits and engineering decision.

Where do uncertainties reside within environmental risk assessments? Expert opinion on uncertainty distributions for pesticide risks to surface water organisms.

Science.gov (United States)

Skinner, Daniel J C; Rocks, Sophie A; Pollard, Simon J T

2016-12-01

A reliable characterisation of uncertainties can aid uncertainty identification during environmental risk assessments (ERAs). However, typologies can be implemented inconsistently, causing uncertainties to go unidentified. We present an approach based on nine structured elicitations, in which subject-matter experts, for pesticide risks to surface water organisms, validate and assess three dimensions of uncertainty: its level (the severity of uncertainty, ranging from determinism to ignorance); nature (whether the uncertainty is epistemic or aleatory); and location (the data source or area in which the uncertainty arises). Risk characterisation contains the highest median levels of uncertainty, associated with estimating, aggregating and evaluating the magnitude of risks. Regarding the locations in which uncertainty is manifest, data uncertainty is dominant in problem formulation, exposure assessment and effects assessment. The comprehensive description of uncertainty described will enable risk analysts to prioritise the required phases, groups of tasks, or individual tasks within a risk analysis according to the highest levels of uncertainty, the potential for uncertainty to be reduced or quantified, or the types of location-based uncertainty, thus aiding uncertainty prioritisation during environmental risk assessments. In turn, it is expected to inform investment in uncertainty reduction or targeted risk management action. Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.

On the use of NDT Data for Reliability-Based Assessment of Existing Timber Structures

DEFF Research Database (Denmark)

Sousa, Hélder S.; Sørensen, John Dalsgaard; Kirkegaard, Poul Henning

2013-01-01

The objective of this paper is to address the possibilities of using non-destructive testing (NDT) data for updating information and obtaining adequate characterization of the reliability level of existing timber structures and, also, for assessing the evolution in time of performance...... of these structures when exposed to deterioration. By improving the knowledge upon the mechanical properties of timber, better and more substantiated decisions after a reliability safety assessment are aimed at. Bayesian methods are used to update the mechanical properties of timber and reliability assessment......, and information of NDT is also used to calibrate these models. The proposed approach is used for reliability assessment of different structural timber systems. Reliability of the structural system is assessed regarding the failure consequences of individual elements defined as key elements which were determined...

GM Risk Assessment

Science.gov (United States)

Sparrow, Penny A. C.

GM risk assessments play an important role in the decision-making process surrounding the regulation, notification and permission to handle Genetically Modified Organisms (GMOs). Ultimately the role of a GM risk assessment will be to ensure the safe handling and containment of the GMO; and to assess any potential impacts on the environment and human health. A risk assessment should answer all ‘what if’ scenarios, based on scientific evidence.

Is the Frontal Assessment Battery reliable in ALS patients?

NARCIS (Netherlands)

Raaphorst, J.; Beeldman, E.; Jaeger, B.; Schmand, B.A.; Berg, L.H. van den; Weikamp, J.G.; Schelhaas, H.J.; Visser, M. de; Haan, R.J. de

2013-01-01

The assessment of frontal functions in ALS patients is important because of the overlap with the behavioural variant of frontotemporal dementia (bvFTD). We investigated the applicability and reliability of the Frontal Assessment Battery (FAB) within a cohort of predominantly prevalent ALS patients.

Addressing dependability by applying an approach for model-based risk assessment

International Nuclear Information System (INIS)

Gran, Bjorn Axel; Fredriksen, Rune; Thunem, Atoosa P.-J.

2007-01-01