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Sample records for system reliability analysis

  1. 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...... (indicators) that can be used to assess the reliability of innovations and new technologies....

  2. Structural systems reliability analysis

    International Nuclear Information System (INIS)

    Frangopol, D.

    1975-01-01

    For an exact evaluation of the reliability of a structure it appears necessary to determine the distribution densities of the loads and resistances and to calculate the correlation coefficients between loads and between resistances. These statistical characteristics can be obtained only on the basis of a long activity period. In case that such studies are missing the statistical properties formulated here give upper and lower bounds of the reliability. (orig./HP) [de

  3. On Bayesian System Reliability Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Soerensen Ringi, M.

    1995-05-01

    The view taken in this thesis is that reliability, the probability that a system will perform a required function for a stated period of time, depends on a person`s state of knowledge. Reliability changes as this state of knowledge changes, i.e. when new relevant information becomes available. Most existing models for system reliability prediction are developed in a classical framework of probability theory and they overlook some information that is always present. Probability is just an analytical tool to handle uncertainty, based on judgement and subjective opinions. It is argued that the Bayesian approach gives a much more comprehensive understanding of the foundations of probability than the so called frequentistic school. A new model for system reliability prediction is given in two papers. The model encloses the fact that component failures are dependent because of a shared operational environment. The suggested model also naturally permits learning from failure data of similar components in non identical environments. 85 refs.

  4. On Bayesian System Reliability Analysis

    International Nuclear Information System (INIS)

    Soerensen Ringi, M.

    1995-01-01

    The view taken in this thesis is that reliability, the probability that a system will perform a required function for a stated period of time, depends on a person's state of knowledge. Reliability changes as this state of knowledge changes, i.e. when new relevant information becomes available. Most existing models for system reliability prediction are developed in a classical framework of probability theory and they overlook some information that is always present. Probability is just an analytical tool to handle uncertainty, based on judgement and subjective opinions. It is argued that the Bayesian approach gives a much more comprehensive understanding of the foundations of probability than the so called frequentistic school. A new model for system reliability prediction is given in two papers. The model encloses the fact that component failures are dependent because of a shared operational environment. The suggested model also naturally permits learning from failure data of similar components in non identical environments. 85 refs

  5. Fundamentals and applications of systems reliability analysis

    International Nuclear Information System (INIS)

    Boesebeck, K.; Heuser, F.W.; Kotthoff, K.

    1976-01-01

    The lecture gives a survey on the application of methods of reliability analysis to assess the safety of nuclear power plants. Possible statements of reliability analysis in connection with specifications of the atomic licensing procedure are especially dealt with. Existing specifications of safety criteria are additionally discussed with the help of reliability analysis by the example of the reliability analysis of a reactor protection system. Beyond the limited application to single safety systems, the significance of reliability analysis for a closed risk concept is explained in the last part of the lecture. (orig./LH) [de

  6. Power system reliability analysis using fault trees

    International Nuclear Information System (INIS)

    Volkanovski, A.; Cepin, M.; Mavko, B.

    2006-01-01

    The power system reliability analysis method is developed from the aspect of reliable delivery of electrical energy to customers. The method is developed based on the fault tree analysis, which is widely applied in the Probabilistic Safety Assessment (PSA). The method is adapted for the power system reliability analysis. The method is developed in a way that only the basic reliability parameters of the analysed power system are necessary as an input for the calculation of reliability indices of the system. The modeling and analysis was performed on an example power system consisting of eight substations. The results include the level of reliability of current power system configuration, the combinations of component failures resulting in a failed power delivery to loads, and the importance factors for components and subsystems. (author)

  7. System Reliability Analysis Considering Correlation of Performances

    International Nuclear Information System (INIS)

    Kim, Saekyeol; Lee, Tae Hee; Lim, Woochul

    2017-01-01

    Reliability analysis of a mechanical system has been developed in order to consider the uncertainties in the product design that may occur from the tolerance of design variables, uncertainties of noise, environmental factors, and material properties. In most of the previous studies, the reliability was calculated independently for each performance of the system. However, the conventional methods cannot consider the correlation between the performances of the system that may lead to a difference between the reliability of the entire system and the reliability of the individual performance. In this paper, the joint probability density function (PDF) of the performances is modeled using a copula which takes into account the correlation between performances of the system. The system reliability is proposed as the integral of joint PDF of performances and is compared with the individual reliability of each performance by mathematical examples and two-bar truss example.

  8. Reliability analysis of flood defence systems

    NARCIS (Netherlands)

    Steenbergen, H.M.G.M.; Lassing, B.L.; Vrouwenvelder, A.C.W.M.; Waarts, P.H.

    2004-01-01

    In recent years an advanced program for the reliability analysis of flood defence systems has been under development. This paper describes the global data requirements for the application and the setup of the models. The analysis generates the probability of system failure and the contribution of

  9. Reliability Analysis of Structural Timber Systems

    DEFF Research Database (Denmark)

    Sørensen, John Dalsgaard; Hoffmeyer, P.

    2000-01-01

    types of redundancy and non-linearity are considered. The statistical characteristics of the load bearing capacity are determined by reliability analysis. Next, more complex systems are considered modelling the mechanical behaviour of timber roof elements I stressed skin panels made of timber. Using...

  10. Reliability analysis and assessment of structural systems

    International Nuclear Information System (INIS)

    Yao, J.T.P.; Anderson, C.A.

    1977-01-01

    The study of structural reliability deals with the probability of having satisfactory performance of the structure under consideration within any specific time period. To pursue this study, it is necessary to apply available knowledge and methodology in structural analysis (including dynamics) and design, behavior of materials and structures, experimental mechanics, and the theory of probability and statistics. In addition, various severe loading phenomena such as strong motion earthquakes and wind storms are important considerations. For three decades now, much work has been done on reliability analysis of structures, and during this past decade, certain so-called 'Level I' reliability-based design codes have been proposed and are in various stages of implementation. These contributions will be critically reviewed and summarized in this paper. Because of the undesirable consequences resulting from the failure of nuclear structures, it is important and desirable to consider the structural reliability in the analysis and design of these structures. Moreover, after these nuclear structures are constructed, it is desirable for engineers to be able to assess the structural reliability periodically as well as immediately following the occurrence of severe loading conditions such as a strong-motion earthquake. During this past decade, increasing use has been made of techniques of system identification in structural engineering. On the basis of non-destructive test results, various methods have been developed to obtain an adequate mathematical model (such as the equations of motion with more realistic parameters) to represent the structural system

  11. RELIABILITY ANALYSIS OF POWER DISTRIBUTION SYSTEMS

    Directory of Open Access Journals (Sweden)

    Popescu V.S.

    2012-04-01

    Full Text Available Power distribution systems are basic parts of power systems and reliability of these systems at present is a key issue for power engineering development and requires special attention. Operation of distribution systems is accompanied by a number of factors that produce random data a large number of unplanned interruptions. Research has shown that the predominant factors that have a significant influence on the reliability of distribution systems are: weather conditions (39.7%, defects in equipment(25% and unknown random factors (20.1%. In the article is studied the influence of random behavior and are presented estimations of reliability of predominantly rural electrical distribution systems.

  12. 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

  13. Diakoptical reliability analysis of transistorized systems

    International Nuclear Information System (INIS)

    Kontoleon, J.M.; Lynn, J.W.; Green, A.E.

    1975-01-01

    Limitations both on high-speed core availability and computation time required for assessing the reliability of large-sized and complex electronic systems, such as used for the protection of nuclear reactors, are very serious restrictions which continuously confront the reliability analyst. Diakoptic methods simplify the solution of the electrical-network problem by subdividing a given network into a number of independent subnetworks and then interconnecting the solutions of these smaller parts by a systematic process involving transformations based on connection-matrix elements associated with the interconnecting links. However, the interconnection process is very complicated and it may be used only if the original system has been cut in such a manner that a relation can be established between the constraints appearing at both sides of the cut. Also, in dealing with transistorized systems, one of the difficulties encountered is that of modelling adequately their performance under various operating conditions, since their parameters are strongly affected by the imposed voltage and current levels. In this paper a new interconnection approach is presented which may be of use in the reliability analysis of large-sized transistorized systems. This is based on the partial optimization of the subdivisions of the torn network as well as on the optimization of the torn paths. The solution of the subdivisions is based on the principles of algebraic topology, with an algebraic structure relating the physical variables in a topological structure which defines the interconnection of the discrete elements. Transistors, and other nonlinear devices, are modelled using their actual characteristics, under normal and abnormal operating conditions. Use of so-called k factors is made to facilitate accounting for use of electrical stresses. The approach is demonstrated by way of an example. (author)

  14. System reliability analysis with natural language and expert's subjectivity

    International Nuclear Information System (INIS)

    Onisawa, T.

    1996-01-01

    This paper introduces natural language expressions and expert's subjectivity to system reliability analysis. To this end, this paper defines a subjective measure of reliability and presents the method of the system reliability analysis using the measure. The subjective measure of reliability corresponds to natural language expressions of reliability estimation, which is represented by a fuzzy set defined on [0,1]. The presented method deals with the dependence among subsystems and employs parametrized operations of subjective measures of reliability which can reflect expert 's subjectivity towards the analyzed system. The analysis results are also expressed by linguistic terms. Finally this paper gives an example of the system reliability analysis by the presented method

  15. Theory of reliable systems. [reliability analysis and on-line fault diagnosis

    Science.gov (United States)

    Meyer, J. F.

    1974-01-01

    Research is reported in the program to refine the current notion of system reliability by identifying and investigating attributes of a system which are important to reliability considerations, and to develop techniques which facilitate analysis of system reliability. Reliability analysis, and on-line fault diagnosis are discussed.

  16. Analysis of reliability parameters for complicated information measurement systems

    OpenAIRE

    Sydor, Andriy

    2012-01-01

    A method of analysis of reliability parameters for complicated systems by means of generating functions is developed taking account of aging of the systems output elements. Main reliability parameters of complicated information measurement systems are examined in this paper.

  17. Reliability analysis and updating of deteriorating systems with subset simulation

    DEFF Research Database (Denmark)

    Schneider, Ronald; Thöns, Sebastian; Straub, Daniel

    2017-01-01

    An efficient approach to reliability analysis of deteriorating structural systems is presented, which considers stochastic dependence among element deterioration. Information on a deteriorating structure obtained through inspection or monitoring is included in the reliability assessment through B...

  18. Brake System Analysis, Reliability Testing And Control Using Bench Experiments

    OpenAIRE

    Xu, Z.; Yang, B.

    1997-01-01

    In this project, the authors investigated the dynamics and reliability of a brake control system using a test bench which is a Lincoln Town Car brake system. The objectives of the project are to: 1) experimentally characterize the brake system; 2) obtain good nonlinear models of the brake system; 3) perform reliability analysis of the brake control system; and, 4) develop algorithms for brake malfunction detection and brake reliability enhancement. By using the brake test bench, the dynamic c...

  19. Reliability analysis of wind embedded power generation system for ...

    African Journals Online (AJOL)

    This paper presents a method for Reliability Analysis of wind energy embedded in power generation system for Indian scenario. This is done by evaluating the reliability index, loss of load expectation, for the power generation system with and without integration of wind energy sources in the overall electric power system.

  20. Discrete event simulation versus conventional system reliability analysis approaches

    DEFF Research Database (Denmark)

    Kozine, Igor

    2010-01-01

    Discrete Event Simulation (DES) environments are rapidly developing and appear to be promising tools for building reliability and risk analysis models of safety-critical systems and human operators. If properly developed, they are an alternative to the conventional human reliability analysis models...

  1. Systems reliability analysis for the national ignition facility

    International Nuclear Information System (INIS)

    Majumdar, K.C.; Annese, C.E.; MacIntyre, A.T.; Sicherman, A.

    1996-01-01

    A Reliability, Availability and Maintainability (RAM) analysis was initiated for the National Ignition Facility (NIF). The NIF is an inertial confinement fusion research facility designed to achieve controlled thermonuclear reaction; the preferred site for the NIF is the Lawrence Livermore National Laboratory (LLNL). The NIF RAM analysis has three purposes: (1) to allocate top level reliability and availability goals for the systems, (2) to develop an operability model for optimum maintainability, and (3) to determine the achievability of the allocated goals of the RAM parameters for the NIF systems and the facility operation as a whole. An allocation model assigns the reliability and availability goals for front line and support systems by a top-down approach; reliability analysis uses a bottom-up approach to determine the system reliability and availability from component level to system level

  2. Reliability analysis of large, complex systems using ASSIST

    Science.gov (United States)

    Johnson, Sally C.

    1988-01-01

    The SURE reliability analysis program is discussed as well as the ASSIST model generation program. It is found that semi-Markov modeling using model reduction strategies with the ASSIST program can be used to accurately solve problems at least as complex as other reliability analysis tools can solve. Moreover, semi-Markov analysis provides the flexibility needed for modeling realistic fault-tolerant systems.

  3. A Passive System Reliability Analysis for a Station Blackout

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-05-03

    The latest iterations of advanced reactor designs have included increased reliance on passive safety systems to maintain plant integrity during unplanned sequences. While these systems are advantageous in reducing the reliance on human intervention and availability of power, the phenomenological foundations on which these systems are built require a novel approach to a reliability assessment. Passive systems possess the unique ability to fail functionally without failing physically, a result of their explicit dependency on existing boundary conditions that drive their operating mode and capacity. Argonne National Laboratory is performing ongoing analyses that demonstrate various methodologies for the characterization of passive system reliability within a probabilistic framework. Two reliability analysis techniques are utilized in this work. The first approach, the Reliability Method for Passive Systems, provides a mechanistic technique employing deterministic models and conventional static event trees. The second approach, a simulation-based technique, utilizes discrete dynamic event trees to treat time- dependent phenomena during scenario evolution. For this demonstration analysis, both reliability assessment techniques are used to analyze an extended station blackout in a pool-type sodium fast reactor (SFR) coupled with a reactor cavity cooling system (RCCS). This work demonstrates the entire process of a passive system reliability analysis, including identification of important parameters and failure metrics, treatment of uncertainties and analysis of results.

  4. Discrete event simulation versus conventional system reliability analysis approaches

    DEFF Research Database (Denmark)

    Kozine, Igor

    2010-01-01

    Discrete Event Simulation (DES) environments are rapidly developing and appear to be promising tools for building reliability and risk analysis models of safety-critical systems and human operators. If properly developed, they are an alternative to the conventional human reliability analysis models...... and systems analysis methods such as fault and event trees and Bayesian networks. As one part, the paper describes briefly the author’s experience in applying DES models to the analysis of safety-critical systems in different domains. The other part of the paper is devoted to comparing conventional approaches...

  5. Use of COMCAN III in system design and reliability analysis

    International Nuclear Information System (INIS)

    Rasmuson, D.M.; Shepherd, J.C.; Marshall, N.H.; Fitch, L.R.

    1982-03-01

    This manual describes the COMCAN III computer program and its use. COMCAN III is a tool that can be used by the reliability analyst performing a probabilistic risk assessment or by the designer of a system desiring improved performance and efficiency. COMCAN III can be used to determine minimal cut sets of a fault tree, to calculate system reliability characteristics, and to perform qualitative common cause failure analysis

  6. Reliability analysis of digital I and C systems at KAERI

    International Nuclear Information System (INIS)

    Kim, Man Cheol

    2013-01-01

    This paper provides an overview of the ongoing research activities on a reliability analysis of digital instrumentation and control (I and C) systems of nuclear power plants (NPPs) performed by the Korea Atomic Energy Research Institute (KAERI). The research activities include the development of a new safety-critical software reliability analysis method by integrating the advantages of existing software reliability analysis methods, a fault coverage estimation method based on fault injection experiments, and a new human reliability analysis method for computer-based main control rooms (MCRs) based on human performance data from the APR-1400 full-scope simulator. The research results are expected to be used to address various issues such as the licensing issues related to digital I and C probabilistic safety assessment (PSA) for advanced digital-based NPPs. (author)

  7. System reliability analysis techniques and their relationship to mechanical/structural reliability problems

    International Nuclear Information System (INIS)

    Bourne, A.J.

    1980-01-01

    The paper gives a brief review of the techniques used in the reliability analysis of functional systems. It also considers some of the aspects arising in applying similar techniques to the reliability analysis of mechanical and structural components. The paper concludes that further data acquisition is of prime importance. Additionally, it is suggested that it may be worthwhile to pay increased attention to the on-line monitoring of deterioration in mechanical and structural elements. (orig.)

  8. Reliability and safety analysis for systems of fusion device

    Energy Technology Data Exchange (ETDEWEB)

    Alzbutas, Robertas, E-mail: robertas.alzbutas@lei.lt; Voronov, Roman

    2015-05-15

    Highlights: • Reliability is very important from fusion devices efficiency perspective. • Rich experience of probabilistic safety analysis exists in nuclear industry. • Reliability and safety analysis was applied for systems of fusion device. • This enables to identify and prioritize availability improvement measures. • Recommendations are based on cost effectiveness for risk decrease options. - Abstract: Fusion energy or thermonuclear power is a promising, literally endless source of energy. Development of fusion power is still under investigation and experimental phase, and a number of fusion devices are under construction in Europe. Since fusion energy is innovative and fusion devices contain unique and expensive equipment, an issue of their reliability is very important from their efficiency perspective. A Reliability, Availability, Maintainability, Inspectability (RAMI) analysis is being performed or is going to be performed in the nearest future for such fusion devices as ITER and DEMO in order to ensure reliable and efficient operation for experiments (e.g., in ITER) or for energy production purposes (e.g., in DEMO). On the other hand, rich experience of the reliability and Probabilistic Safety Analysis (PSA) exists in nuclear industry for fission power plants and other nuclear installations. In this paper, the Wendelstein 7-X (W7-X) device is mainly considered. This stellarator device is in commissioning stage in the Max-Planck-Institut für Plasmaphysik, Greifswald, Germany (IPP). In the frame of cooperation between the IPP and the Lithuanian Energy Institute (LEI) under the European Fusion Development Agreement a pilot project of a reliability analysis of the W7-X systems was performed with a purpose to adopt Nuclear Power Plant (NPP) PSA experience for fusion device systems. During the project reliability and safety (risk) analysis of a Divertor Target Cooling Circuit, which is an important system for permanent and reliable operation of in

  9. Reliability Analysis of a Two Dissimilar Unit Cold Standby System ...

    African Journals Online (AJOL)

    reliability and availability analysis are evaluated. This proposed system has been investigated under three modes: normal, partial failure, total failure. The failure and the repair time are assumed to have exponential distribution. The effect of failure rate on meantime to system failure ( MTSF ), steady state availability (. ( ). T.

  10. Reliability analysis framework for computer-assisted medical decision systems

    International Nuclear Information System (INIS)

    Habas, Piotr A.; Zurada, Jacek M.; Elmaghraby, Adel S.; Tourassi, Georgia D.

    2007-01-01

    We present a technique that enhances computer-assisted decision (CAD) systems with the ability to assess the reliability of each individual decision they make. Reliability assessment is achieved by measuring the accuracy of a CAD system with known cases similar to the one in question. The proposed technique analyzes the feature space neighborhood of the query case to dynamically select an input-dependent set of known cases relevant to the query. This set is used to assess the local (query-specific) accuracy of the CAD system. The estimated local accuracy is utilized as a reliability measure of the CAD response to the query case. The underlying hypothesis of the study is that CAD decisions with higher reliability are more accurate. The above hypothesis was tested using a mammographic database of 1337 regions of interest (ROIs) with biopsy-proven ground truth (681 with masses, 656 with normal parenchyma). Three types of decision models, (i) a back-propagation neural network (BPNN), (ii) a generalized regression neural network (GRNN), and (iii) a support vector machine (SVM), were developed to detect masses based on eight morphological features automatically extracted from each ROI. The performance of all decision models was evaluated using the Receiver Operating Characteristic (ROC) analysis. The study showed that the proposed reliability measure is a strong predictor of the CAD system's case-specific accuracy. Specifically, the ROC area index for CAD predictions with high reliability was significantly better than for those with low reliability values. This result was consistent across all decision models investigated in the study. The proposed case-specific reliability analysis technique could be used to alert the CAD user when an opinion that is unlikely to be reliable is offered. The technique can be easily deployed in the clinical environment because it is applicable with a wide range of classifiers regardless of their structure and it requires neither additional

  11. Reliability analysis of service water system under earthquake

    International Nuclear Information System (INIS)

    Yu Yu; Qian Xiaoming; Lu Xuefeng; Wang Shengfei; Niu Fenglei

    2013-01-01

    Service water system is one of the important safety systems in nuclear power plant, whose failure probability is always gained by system reliability analysis. The probability of equipment failure under the earthquake is the function of the peak acceleration of earthquake motion, while the occurrence of earthquake is of randomicity, thus the traditional fault tree method in current probability safety assessment is not powerful enough to deal with such case of conditional probability problem. An analysis frame was put forward for system reliability evaluation in seismic condition in this paper, in which Monte Carlo simulation was used to deal with conditional probability problem. Annual failure probability of service water system was calculated, and failure probability of 1.46X10 -4 per year was obtained. The analysis result is in accordance with the data which indicate equipment seismic resistance capability, and the rationality of the model is validated. (authors)

  12. Reliability analysis of two unit parallel repairable industrial system

    Directory of Open Access Journals (Sweden)

    Mohit Kumar Kakkar

    2015-09-01

    Full Text Available The aim of this work is to present a reliability and profit analysis of a two-dissimilar parallel unit system under the assumption that operative unit cannot fail after post repair inspection and replacement and there is only one repair facility. Failure and repair times of each unit are assumed to be uncorrelated. Using regenerative point technique various reliability characteristics are obtained which are useful to system designers and industrial managers. Graphical behaviors of mean time to system failure (MTSF and profit function have also been studied. In this paper, some important measures of reliability characteristics of a two non-identical unit standby system model with repair, inspection and post repair are obtained using regenerative point technique.

  13. Analysis of the Reliability of the "Alternator- Alternator Belt" System

    Directory of Open Access Journals (Sweden)

    Ivan Mavrin

    2012-10-01

    Full Text Available Before starting and also during the exploitation of va1ioussystems, it is vety imp011ant to know how the system and itsparts will behave during operation regarding breakdowns, i.e.failures. It is possible to predict the service behaviour of a systemby determining the functions of reliability, as well as frequencyand intensity of failures.The paper considers the theoretical basics of the functionsof reliability, frequency and intensity of failures for the twomain approaches. One includes 6 equal intetvals and the other13 unequal intetvals for the concrete case taken from practice.The reliability of the "alternator- alternator belt" system installedin the buses, has been analysed, according to the empiricaldata on failures.The empitical data on failures provide empirical functionsof reliability and frequency and intensity of failures, that arepresented in tables and graphically. The first analysis perfO!med by dividing the mean time between failures into 6 equaltime intervals has given the forms of empirical functions of fa ilurefrequency and intensity that approximately cotTespond totypical functions. By dividing the failure phase into 13 unequalintetvals with two failures in each interval, these functions indicateexplicit transitions from early failure inte1val into the randomfailure interval, i.e. into the ageing intetval. Functions thusobtained are more accurate and represent a better solution forthe given case.In order to estimate reliability of these systems with greateraccuracy, a greater number of failures needs to be analysed.

  14. System Reliability Engineering

    International Nuclear Information System (INIS)

    Lim, Tae Jin

    2005-02-01

    This book tells of reliability engineering, which includes quality and reliability, reliability data, importance of reliability engineering, reliability and measure, the poisson process like goodness of fit test and the poisson arrival model, reliability estimation like exponential distribution, reliability of systems, availability, preventive maintenance such as replacement policies, minimal repair policy, shock models, spares, group maintenance and periodic inspection, analysis of common cause failure, and analysis model of repair effect.

  15. A computer system for the analysis of integrated circuit reliability

    Science.gov (United States)

    Mauri, P.

    1989-12-01

    The formulation of total reliability assessment of integrated circuits involves an increasing amount of knowledge and data and hence it requires increasing computerized assistance. To perform this an information system has been designed and implemented. Following engineering practice, the key features of the system are (1) the collection of different types of data, e.g. electrical parameter measurements and qualitative description of the mode and the mechanism of failure and (2) the implementation of procedures coming from methods often applied, e.g. statistical or new approaches, such as formalization of cause-effect chains as studied for artificial intelligence applications. The system architecture has been designed so as to allow direct user maintenance, and hence a quick updating of reliability knowledge and information. Furthermore, its modularity eases the implementation of new procedures. Computer support improves the quality of data analysis and allows for the application of new methods and models.

  16. Review of the treat upgrade reactor scram system reliability analysis

    International Nuclear Information System (INIS)

    Montague, D.F.; Fussell, J.B.; Krois, P.A.; Morelock, T.C.; Knee, H.E.; Manning, J.J.; Haas, P.M.; West, K.W.

    1984-10-01

    In order to resolve some key LMFBR safety issues, ANL personnel are modifying the TREAT reactor to handle much larger experiments. As a result of these modifications, the upgraded Treat reactor will not always operate in a self-limited mode. During certain experiments in the upgraded TREAT reactor, it is possible that the fuel could be damaged by overheating if, once the computer systems fail, the reactor scram system (RSS) fails on demand. To help ensure that the upgraded TREAT reactor is shut down when required, ANL personnel have designed a triply redundant RSS for the facility. The RSS is designed to meet three reliability goals: (1) a loss of capability failure probability of 10 -9 /demand (independent failures only); (2) an inadvertent shutdown probability of 10 -3 /experiment; and (3) protection agaist any known potential common cause failures. According to ANL's reliability analysis of the RSS, this system substantially meets these goals

  17. Failure and Reliability Analysis for the Master Pump Shutdown System

    Energy Technology Data Exchange (ETDEWEB)

    BEVINS, R.R.

    2000-09-05

    The Master Pump Shutdown System (MPSS) will be installed in the 200 Areas of the Hanford Site to monitor and control the transfer of liquid waste between tank farms and between the 200 West and 200 East areas through the Cross-Site Transfer Line. The Safety Function provided by the MPSS is to shutdown any waste transfer process within or between tank farms if a waste leak should occur along the selected transfer route. The MPSS, which provides this Safety Class Function, is composed of Programmable Logic Controllers (PLCs), interconnecting wires, relays, Human to Machine Interfaces (HMI), and software. These components are defined as providing a Safety Class Function and will be designated in this report as MPSS/PLC. Input signals to the MPSS/PLC are provided by leak detection systems from each of the tank farm leak detector locations along the waste transfer route. The combination of the MPSS/PLC, leak detection system, and transfer pump controller system will be referred to as MPSS/SYS. The components addressed in this analysis are associated with the MPSS/SYS. The purpose of this failure and reliability analysis is to address the following design issues of the Project Development Specification (PDS) for the MPSS/SYS (HNF 2000a): (1) Single Component Failure Criterion, (2) System Status Upon Loss of Electrical Power, (3) Physical Separation of Safety Class cables, (4) Physical Isolation of Safety Class Wiring from General Service Wiring, and (5) Meeting the MPSS/PLC Option 1b (RPP 1999) Reliability estimate. The failure and reliability analysis examined the system on a component level basis and identified any hardware or software elements that could fail and/or prevent the system from performing its intended safety function.

  18. Nuclear power plant emergency core cooling system reliability analysis - reliability estimation for small LOCA

    International Nuclear Information System (INIS)

    Vojnovic, Dj.

    1989-01-01

    System performance reliability depends not only on its own availability but also on requirements which are placed the system. This paper shows a way of system performance reliability estimation for a NPP Emergency Core Cooling System in case of small LOCA. The event scenario and requirements for systems are determined with event tree. Finally, the ECCS reliability estimation is performed on the basis of system requirements. (author)

  19. Reliability Analysis of the CERN Radiation Monitoring Electronic System CROME

    CERN Document Server

    AUTHOR|(CDS)2126870

    For the new in-house developed CERN Radiation Monitoring Electronic System (CROME) a reliability analysis is necessary to ensure compliance with the statu-tory requirements regarding the Safety Integrity Level. The required Safety Integrity Level by IEC 60532 standard is SIL 2 (for the Safety Integrated Functions Measurement, Alarm Triggering and Interlock Triggering). The first step of the reliability analysis was a system and functional analysis which served as basis for the implementation of the CROME system in the software “Iso-graph”. In the “Prediction” module of Isograph the failure rates of all components were calculated. Failure rates for passive components were calculated by the Military Standard 217 and failure rates for active components were obtained from lifetime tests by the manufacturers. The FMEA was carried out together with the board designers and implemented in the “FMECA” module of Isograph. The FMEA served as basis for the Fault Tree Analysis and the detection of weak points...

  20. Method for solving logical loops in system reliability analysis

    International Nuclear Information System (INIS)

    Matsuoka, Takeshi

    2010-01-01

    The procedure for solving Boolean equations with unknown element(s) is presented. Discussions are made for operation of typical engineering systems with loop structure. It is revealed that components are necessary to be classified into three types. Time-dependent expression of a component's state is given and operating states of loop structures are identified by Boolean algebraic procedure. The procedure proposed in this paper is applicable to the condition that components can start at any time in system operational sequence, and each component has multiple chances to be started. A sample system was analyzed and the result was confirmed by a step by step analysis. The procedure shown in this paper is very useful in evaluating engineering systems which have logical loop structure(s), and also useful in effectively designing high reliable systems. (author)

  1. Reliability analysis of self-actuated shutdown system

    International Nuclear Information System (INIS)

    Itooka, S.; Kumasaka, K.; Okabe, A.; Satoh, K.; Tsukui, Y.

    1991-01-01

    An analytical study was performed for the reliability of a self-actuated shutdown system (SASS) under the unprotected loss of flow (ULOF) event in a typical loop-type liquid metal fast breeder reactor (LMFBR) by the use of the response surface Monte Carlo analysis method. Dominant parameters for the SASS, such as Curie point characteristics, subassembly outlet coolant temperature, electromagnetic surface condition, etc., were selected and their probability density functions (PDFs) were determined by the design study information and experimental data. To get the response surface function (RSF) for the maximum coolant temperature, transient analyses of ULOF were performed by utilizing the experimental design method in the determination of analytical cases. Then, the RSF was derived by the multi-variable regression analysis. The unreliability of the SASS was evaluated as a probability that the maximum coolant temperature exceeded an acceptable level, employing the Monte Carlo calculation using the above PDFs and RSF. In this study, sensitivities to the dominant parameter were compared. The dispersion of subassembly outlet coolant temperature near the SASS-was found to be one of the most sensitive parameters. Fault tree analysis was performed using this value for the SASS in order to evaluate the shutdown system reliability. As a result of this study, the effectiveness of the SASS on the reliability improvement in the LMFBR shutdown system was analytically confirmed. This study has been performed as a part of joint research and development projects for DFBR under the sponsorship of the nine Japanese electric power companies, Electric Power Development Company and the Japan Atomic Power Company. (author)

  2. Reliability and availability requirements analysis for DEMO: fuel cycle system

    International Nuclear Information System (INIS)

    Pinna, T.; Borgognoni, F.

    2015-01-01

    The Demonstration Power Plant (DEMO) will be a fusion reactor prototype designed to demonstrate the capability to produce electrical power in a commercially acceptable way. Two of the key elements of the engineering development of the DEMO reactor are the definitions of reliability and availability requirements (or targets). The availability target for a hypothesized Fuel Cycle has been analysed as a test case. The analysis has been done on the basis of the experience gained in operating existing tokamak fusion reactors and developing the ITER design. Plant Breakdown Structure (PBS) and Functional Breakdown Structure (FBS) related to the DEMO Fuel Cycle and correlations between PBS and FBS have been identified. At first, a set of availability targets has been allocated to the various systems on the basis of their operating, protection and safety functions. 75% and 85% of availability has been allocated to the operating functions of fuelling system and tritium plant respectively. 99% of availability has been allocated to the overall systems in executing their safety functions. The chances of the systems to achieve the allocated targets have then been investigated through a Failure Mode and Effect Analysis and Reliability Block Diagram analysis. The following results have been obtained: 1) the target of 75% for the operations of the fuelling system looks reasonable, while the target of 85% for the operations of the whole tritium plant should be reduced to 80%, even though all the tritium plant systems can individually reach quite high availability targets, over 90% - 95%; 2) all the DEMO Fuel Cycle systems can reach the target of 99% in accomplishing their safety functions. (authors)

  3. Development of the integrated system reliability analysis code MODULE

    International Nuclear Information System (INIS)

    Han, S.H.; Yoo, K.J.; Kim, T.W.

    1987-01-01

    The major components in a system reliability analysis are the determination of cut sets, importance measure, and uncertainty analysis. Various computer codes have been used for these purposes. For example, SETS and FTAP are used to determine cut sets; Importance for importance calculations; and Sample, CONINT, and MOCUP for uncertainty analysis. There have been problems when the codes run each other and the input and output are not linked, which could result in errors when preparing input for each code. The code MODULE was developed to carry out the above calculations simultaneously without linking input and outputs to other codes. MODULE can also prepare input for SETS for the case of a large fault tree that cannot be handled by MODULE. The flow diagram of the MODULE code is shown. To verify the MODULE code, two examples are selected and the results and computation times are compared with those of SETS, FTAP, CONINT, and MOCUP on both Cyber 170-875 and IBM PC/AT. Two examples are fault trees of the auxiliary feedwater system (AFWS) of Korea Nuclear Units (KNU)-1 and -2, which have 54 gates and 115 events, 39 gates and 92 events, respectively. The MODULE code has the advantage that it can calculate the cut sets, importances, and uncertainties in a single run with little increase in computing time over other codes and that it can be used in personal computers

  4. Reliability modeling and analysis of smart power systems

    CERN Document Server

    Karki, Rajesh; Verma, Ajit Kumar

    2014-01-01

    The volume presents the research work in understanding, modeling and quantifying the risks associated with different ways of implementing smart grid technology in power systems in order to plan and operate a modern power system with an acceptable level of reliability. Power systems throughout the world are undergoing significant changes creating new challenges to system planning and operation in order to provide reliable and efficient use of electrical energy. The appropriate use of smart grid technology is an important drive in mitigating these problems and requires considerable research acti

  5. Embedded mechatronic systems 1 analysis of failures, predictive reliability

    CERN Document Server

    El Hami, Abdelkhalak

    2015-01-01

    In operation, mechatronics embedded systems are stressed by loads of different causes: climate (temperature, humidity), vibration, electrical and electromagnetic. These stresses in components which induce failure mechanisms should be identified and modeled for better control. AUDACE is a collaborative project of the cluster Mov'eo that address issues specific to mechatronic reliability embedded systems. AUDACE means analyzing the causes of failure of components of mechatronic systems onboard. The goal of the project is to optimize the design of mechatronic devices by reliability. The projec

  6. Windfarm generation assessment for reliability analysis of power systems

    DEFF Research Database (Denmark)

    Negra, N.B.; Holmstrøm, O.; Bak-Jensen, B.

    2007-01-01

    Due to the fast development of wind generation in the past ten years, increasing interest has been paid to techniques for assessing different aspects of power systems with a large amount of installed wind generation. One of these aspects concerns power system reliability. Windfarm modelling plays...... in a reliability model and the generation of a windfarm is evaluated by means of sequential Monte Carlo simulation. Results are used to analyse how each mentioned Factor influences the assessment, and why and when they should be included in the model....

  7. Windfarm Generation Assessment for Reliability Analysis of Power Systems

    DEFF Research Database (Denmark)

    Barberis Negra, Nicola; Bak-Jensen, Birgitte; Holmstrøm, O.

    2007-01-01

    Due to the fast development of wind generation in the past ten years, increasing interest has been paid to techniques for assessing different aspects of power systems with a large amount of installed wind generation. One of these aspects concerns power system reliability. Windfarm modelling plays...... in a reliability model and the generation of a windfarm is evaluated by means of sequential Monte Carlo simulation. Results are used to analyse how each mentioned Factor influences the assessment, and why and when they should be included in the model....

  8. Windfarm Generation Assessment for ReliabilityAnalysis of Power Systems

    DEFF Research Database (Denmark)

    Negra, Nicola Barberis; Holmstrøm, Ole; Bak-Jensen, Birgitte

    2007-01-01

    Due to the fast development of wind generation in the past ten years, increasing interest has been paid to techniques for assessing different aspects of power systems with a large amount of installed wind generation. One of these aspects concerns power system reliability. Windfarm modelling plays...... in a reliability model and the generation of a windfarm is evaluated by means of sequential Monte Carlo simulation. Results are used to analyse how each mentioned Factor influences the assessment, and why and when they should be included in the model....

  9. Reliability analysis of the service water system of Angra 1 reactor

    International Nuclear Information System (INIS)

    Tayt-Sohn, L.C.; Oliveira, L.F.S. de.

    1984-01-01

    A reliability analysis of the service water system is done aiming to use in the evaluation of the non reliability of the Component Cooling System (SRC) for great loss of cooling accidents in nuclear power plants. (E.G.) [pt

  10. Reliability analysis of the service water system of Angra 1 reactor

    International Nuclear Information System (INIS)

    Oliveira, L.F.S. de; Fleming, P.V.; Frutuoso e Melo, P.F.F.; Tayt-Sohn, L.C.

    1983-01-01

    A reliability analysis of the service water system is done aiming to use in the evaluation of the non reliability of the component cooling system (SRC) for great loss of cooling accidents in nuclear power plants. (E.G.) [pt

  11. Reliability analysis of Airbus A-330 computer flight management system

    OpenAIRE

    Fajmut, Metod

    2010-01-01

    Diploma thesis deals with digitized, computerized flight control system »Fly-by-wire« and security aspects of the computer system of an aircraft Airbus A330. As for space and military aircraft structures is also in commercial airplanes, much of the financial contribution devoted to reliability. Conventional aircraft control systems have, and some are still, to rely on mechanical and hydraulic connections between the controls on aircraft operated by the pilot and control surfaces. But newer a...

  12. System Reliability Analysis Capability and Surrogate Model Application in RAVEN

    Energy Technology Data Exchange (ETDEWEB)

    Rabiti, Cristian [Idaho National Lab. (INL), Idaho Falls, ID (United States); Alfonsi, Andrea [Idaho National Lab. (INL), Idaho Falls, ID (United States); Huang, Dongli [Idaho National Lab. (INL), Idaho Falls, ID (United States); Gleicher, Frederick [Idaho National Lab. (INL), Idaho Falls, ID (United States); Wang, Bei [Idaho National Lab. (INL), Idaho Falls, ID (United States); Adbel-Khalik, Hany S. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Pascucci, Valerio [Idaho National Lab. (INL), Idaho Falls, ID (United States); Smith, Curtis L. [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2015-11-01

    This report collect the effort performed to improve the reliability analysis capabilities of the RAVEN code and explore new opportunity in the usage of surrogate model by extending the current RAVEN capabilities to multi physics surrogate models and construction of surrogate models for high dimensionality fields.

  13. Length effects in reliability analysis of flood protection systems

    NARCIS (Netherlands)

    Vrouwenvelder, A.C.W.M.

    2006-01-01

    The defence against flooding by storm surges and large river discharges are provided by complex systems of dikes, dunes, retaining walls, higher grounds, barriers, locks and so on. Spatial correlations inside and between the various components play an important role in the reliability and risk

  14. Analysis and Application of Reliability

    International Nuclear Information System (INIS)

    Jeong, Hae Seong; Park, Dong Ho; Kim, Jae Ju

    1999-05-01

    This book tells of analysis and application of reliability, which includes definition, importance and historical background of reliability, function of reliability and failure rate, life distribution and assumption of reliability, reliability of unrepaired system, reliability of repairable system, sampling test of reliability, failure analysis like failure analysis by FEMA and FTA, and cases, accelerated life testing such as basic conception, acceleration and acceleration factor, and analysis of accelerated life testing data, maintenance policy about alternation and inspection.

  15. Reliability Analysis Multiple Redundancy Controller for Nuclear Safety Systems

    International Nuclear Information System (INIS)

    Son, Gwangseop; Kim, Donghoon; Son, Choulwoong

    2013-01-01

    This controller is configured for multiple modular redundancy (MMR) composed of dual modular redundancy (DMR) and triple modular redundancy (TMR). The architecture of MRC is briefly described, and the Markov model is developed. Based on the model, the reliability and Mean Time To Failure (MTTF) are analyzed. In this paper, the architecture of MRC for nuclear safety systems is described. The MRC is configured for multiple modular redundancy (MMR) composed of dual modular redundancy (DMR) and triple modular redundancy (TMR). Markov models for MRC architecture was developed, and then the reliability was analyzed by using the model. From the reliability analyses for the MRC, it is obtained that the failure rate of each module in the MRC should be less than 2 Χ 10 -4 /hour and the MTTF average increase rate depending on FCF increment, i. e. ΔMTTF/ΔFCF, is 4 months/0.1

  16. Reliability Analysis Study of Digital Reactor Protection System in Nuclear Power Plant

    International Nuclear Information System (INIS)

    Guo, Xiao Ming; Liu, Tao; Tong, Jie Juan; Zhao, Jun

    2011-01-01

    The Digital I and C systems are believed to improve a plants safety and reliability generally. The reliability analysis of digital I and C system has become one research hotspot. Traditional fault tree method is one of means to quantify the digital I and C system reliability. Review of advanced nuclear power plant AP1000 digital protection system evaluation makes clear both the fault tree application and analysis process to the digital system reliability. One typical digital protection system special for advanced reactor has been developed, which reliability evaluation is necessary for design demonstration. The typical digital protection system construction is introduced in the paper, and the process of FMEA and fault tree application to the digital protection system reliability evaluation are described. Reliability data and bypass logic modeling are two points giving special attention in the paper. Because the factors about time sequence and feedback not exist in reactor protection system obviously, the dynamic feature of digital system is not discussed

  17. Wind energy Computerized Maintenance Management System (CMMS) : data collection recommendations for reliability analysis.

    Energy Technology Data Exchange (ETDEWEB)

    Peters, Valerie A.; Ogilvie, Alistair; Veers, Paul S.

    2009-09-01

    This report addresses the general data requirements for reliability analysis of fielded wind turbines and other wind plant equipment. The report provides a list of the data needed to support reliability and availability analysis, and gives specific recommendations for a Computerized Maintenance Management System (CMMS) to support automated analysis. This data collection recommendations report was written by Sandia National Laboratories to address the general data requirements for reliability analysis of fielded wind turbines. This report is intended to help the reader develop a basic understanding of what data are needed from a Computerized Maintenance Management System (CMMS) and other data systems, for reliability analysis. The report provides: (1) a list of the data needed to support reliability and availability analysis; and (2) specific recommendations for a CMMS to support automated analysis. Though written for reliability analysis of wind turbines, much of the information is applicable to a wider variety of equipment and a wider variety of analysis and reporting needs.

  18. Study on the application of dimensionality reduction method on reliability and reliability sensitivity analysis of random vibration systems

    Directory of Open Access Journals (Sweden)

    Haochuan Li

    2015-10-01

    Full Text Available The application of dimensionality reduction method on the reliability and reliability sensitivity analysis of vibration systems was examined. The dimensionality of a vibration reliability problem was reduced to only two independent dimensions by the means of polar transformation. As the safe and failure classes of samples are clearly distinguishable and occupy a standard position in a two-dimensional plot in the case that the important direction exists, the relevant samples are selected visually. The reliability and reliability sensitivity problems were solved using the position of the relevant samples. Before the reliability and reliability sensitivity estimation, an essential visualization analysis is conducted to examine the capacity of the method in terms of the existence of the important direction which is used to reduce the dimensionality of the reliability problem. In order to calculate the design point correctly, the improved Hasofer–Lind–Rackwitz–Fiessler method was extended with a procedure for determining the perturbation in the calculation of the gradient vector by finite differences according to the numerical precision of the limit state function. The dimensionality reduction method saves the numbers of calling limit state function a lot and has the same accuracy as Monte Carlo method. Examples involving single and multiple degree-of-freedom nonlinear vibration systems were used to demonstrate the approach.

  19. Reliability Analysis of a Two Dissimilar Unit Cold Standby System ...

    African Journals Online (AJOL)

    The effect of failure rate on meantime to system failure (MTSF ), steady state availability ( AT (∞) ) and the profit function PF(∞) of the system are compared. It was found thatMTSF , AT (∞) , and PF(∞) are decreasing with the increase of the failure rate. Keywords: Cost analysis, Meantime to System Failure, Steady State ...

  20. Reliability Worth Analysis of Distribution Systems Using Cascade Correlation Neural Networks

    DEFF Research Database (Denmark)

    Heidari, Alireza; Agelidis, Vassilios; Pou, Josep

    2018-01-01

    Reliability worth analysis is of great importance in the area of distribution network planning and operation. The reliability worth's precision can be affected greatly by the customer interruption cost model used. The choice of the cost models can change system and load point reliability indices...

  1. Reliability importance analysis of Markovian systems at steady state using perturbation analysis

    International Nuclear Information System (INIS)

    Phuc Do Van; Barros, Anne; Berenguer, Christophe

    2008-01-01

    Sensitivity analysis has been primarily defined for static systems, i.e. systems described by combinatorial reliability models (fault or event trees). Several structural and probabilistic measures have been proposed to assess the components importance. For dynamic systems including inter-component and functional dependencies (cold spare, shared load, shared resources, etc.), and described by Markov models or, more generally, by discrete events dynamic systems models, the problem of sensitivity analysis remains widely open. In this paper, the perturbation method is used to estimate an importance factor, called multi-directional sensitivity measure, in the framework of Markovian systems. Some numerical examples are introduced to show why this method offers a promising tool for steady-state sensitivity analysis of Markov processes in reliability studies

  2. A survey on reliability and safety analysis techniques of robot systems in nuclear power plants

    International Nuclear Information System (INIS)

    Eom, H.S.; Kim, J.H.; Lee, J.C.; Choi, Y.R.; Moon, S.S.

    2000-12-01

    The reliability and safety analysis techniques was surveyed for the purpose of overall quality improvement of reactor inspection system which is under development in our current project. The contents of this report are : 1. Reliability and safety analysis techniques suvey - Reviewed reliability and safety analysis techniques are generally accepted techniques in many industries including nuclear industry. And we selected a few techniques which are suitable for our robot system. They are falut tree analysis, failure mode and effect analysis, reliability block diagram, markov model, combinational method, and simulation method. 2. Survey on the characteristics of robot systems which are distinguished from other systems and which are important to the analysis. 3. Survey on the nuclear environmental factors which affect the reliability and safety analysis of robot system 4. Collection of the case studies of robot reliability and safety analysis which are performed in foreign countries. The analysis results of this survey will be applied to the improvement of reliability and safety of our robot system and also will be used for the formal qualification and certification of our reactor inspection system

  3. A survey on reliability and safety analysis techniques of robot systems in nuclear power plants

    Energy Technology Data Exchange (ETDEWEB)

    Eom, H.S.; Kim, J.H.; Lee, J.C.; Choi, Y.R.; Moon, S.S

    2000-12-01

    The reliability and safety analysis techniques was surveyed for the purpose of overall quality improvement of reactor inspection system which is under development in our current project. The contents of this report are : 1. Reliability and safety analysis techniques suvey - Reviewed reliability and safety analysis techniques are generally accepted techniques in many industries including nuclear industry. And we selected a few techniques which are suitable for our robot system. They are falut tree analysis, failure mode and effect analysis, reliability block diagram, markov model, combinational method, and simulation method. 2. Survey on the characteristics of robot systems which are distinguished from other systems and which are important to the analysis. 3. Survey on the nuclear environmental factors which affect the reliability and safety analysis of robot system 4. Collection of the case studies of robot reliability and safety analysis which are performed in foreign countries. The analysis results of this survey will be applied to the improvement of reliability and safety of our robot system and also will be used for the formal qualification and certification of our reactor inspection system.

  4. Hawaii electric system reliability.

    Energy Technology Data Exchange (ETDEWEB)

    Silva Monroy, Cesar Augusto; Loose, Verne William

    2012-09-01

    This report addresses Hawaii electric system reliability issues; greater emphasis is placed on short-term reliability but resource adequacy is reviewed in reference to electric consumers' views of reliability %E2%80%9Cworth%E2%80%9D and the reserve capacity required to deliver that value. The report begins with a description of the Hawaii electric system to the extent permitted by publicly available data. Electrical engineering literature in the area of electric reliability is researched and briefly reviewed. North American Electric Reliability Corporation standards and measures for generation and transmission are reviewed and identified as to their appropriateness for various portions of the electric grid and for application in Hawaii. Analysis of frequency data supplied by the State of Hawaii Public Utilities Commission is presented together with comparison and contrast of performance of each of the systems for two years, 2010 and 2011. Literature tracing the development of reliability economics is reviewed and referenced. A method is explained for integrating system cost with outage cost to determine the optimal resource adequacy given customers' views of the value contributed by reliable electric supply. The report concludes with findings and recommendations for reliability in the State of Hawaii.

  5. Hawaii Electric System Reliability

    Energy Technology Data Exchange (ETDEWEB)

    Loose, Verne William [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Silva Monroy, Cesar Augusto [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2012-08-01

    This report addresses Hawaii electric system reliability issues; greater emphasis is placed on short-term reliability but resource adequacy is reviewed in reference to electric consumers’ views of reliability “worth” and the reserve capacity required to deliver that value. The report begins with a description of the Hawaii electric system to the extent permitted by publicly available data. Electrical engineering literature in the area of electric reliability is researched and briefly reviewed. North American Electric Reliability Corporation standards and measures for generation and transmission are reviewed and identified as to their appropriateness for various portions of the electric grid and for application in Hawaii. Analysis of frequency data supplied by the State of Hawaii Public Utilities Commission is presented together with comparison and contrast of performance of each of the systems for two years, 2010 and 2011. Literature tracing the development of reliability economics is reviewed and referenced. A method is explained for integrating system cost with outage cost to determine the optimal resource adequacy given customers’ views of the value contributed by reliable electric supply. The report concludes with findings and recommendations for reliability in the State of Hawaii.

  6. Summary of the preparation of methodology for digital system reliability analysis for PSA purposes

    International Nuclear Information System (INIS)

    Hustak, S.; Babic, P.

    2001-12-01

    The report is structured as follows: Specific features of and requirements for the digital part of NPP Instrumentation and Control (I and C) systems (Computer-controlled digital technologies and systems of the NPP I and C system; Specific types of digital technology failures and preventive provisions; Reliability requirements for the digital parts of I and C systems; Safety requirements for the digital parts of I and C systems; Defence-in-depth). Qualitative analyses of NPP I and C system reliability and safety (Introductory system analysis; Qualitative requirements for and proof of NPP I and C system reliability and safety). Quantitative reliability analyses of the digital parts of I and C systems (Selection of a suitable quantitative measure of digital system reliability; Selected qualitative and quantitative findings regarding digital system reliability; Use of relations among the occurrences of the various types of failure). Mathematical section in support of the calculation of the various types of indices (Boolean reliability models, Markovian reliability models). Example of digital system analysis (Description of a selected protective function and the relevant digital part of the I and C system; Functional chain examined, its components and fault tree). (P.A.)

  7. Reliability and life-cycle analysis of deteriorating systems

    CERN Document Server

    Sánchez-Silva, Mauricio

    2016-01-01

    This book compiles and critically discusses modern engineering system degradation models and their impact on engineering decisions. In particular, the authors focus on modeling the uncertain nature of degradation considering both conceptual discussions and formal mathematical formulations. It also describes the basics concepts and the various modeling aspects of life-cycle analysis (LCA).  It highlights the role of degradation in LCA and defines optimum design and operation parameters. Given the relationship between operational decisions and the performance of the system’s condition over time, maintenance models are also discussed. The concepts and models presented have applications in a large variety of engineering fields such as Civil, Environmental, Industrial, Electrical and Mechanical engineering. However, special emphasis is given to problems related to large infrastructure systems. The book is intended to be used both as a reference resource for researchers and practitioners and as an academic text ...

  8. Aviation Fuel System Reliability and Fail-Safety Analysis. Promising Alternative Ways for Improving the Fuel System Reliability

    Directory of Open Access Journals (Sweden)

    I. S. Shumilov

    2017-01-01

    Full Text Available The paper deals with design requirements for an aviation fuel system (AFS, AFS basic design requirements, reliability, and design precautions to avoid AFS failure. Compares the reliability and fail-safety of AFS and aircraft hydraulic system (AHS, considers the promising alternative ways to raise reliability of fuel systems, as well as elaborates recommendations to improve reliability of the pipeline system components and pipeline systems, in general, based on the selection of design solutions.It is extremely advisable to design the AFS and AHS in accordance with Aviation Regulations АП25 and Accident Prevention Guidelines, ICAO (International Civil Aviation Association, which will reduce risk of emergency situations, and in some cases even avoid heavy disasters.ATS and AHS designs should be based on the uniform principles to ensure the highest reliability and safety. However, currently, this principle is not enough kept, and AFS looses in reliability and fail-safety as compared with AHS. When there are the examined failures (single and their combinations the guidelines to ensure the AFS efficiency should be the same as those of norm-adopted in the Regulations АП25 for AHS. This will significantly increase reliability and fail-safety of the fuel systems and aircraft flights, in general, despite a slight increase in AFS mass.The proposed improvements through the use of components redundancy of the fuel system will greatly raise reliability of the fuel system of a passenger aircraft, which will, without serious consequences for the flight, withstand up to 2 failures, its reliability and fail-safety design will be similar to those of the AHS, however, above improvement measures will lead to a slightly increasing total mass of the fuel system.It is advisable to set a second pump on the engine in parallel with the first one. It will run in case the first one fails for some reasons. The second pump, like the first pump, can be driven from the

  9. Reliability analysis of microcomputer boards and computer based systems important to safety of nuclear plants

    International Nuclear Information System (INIS)

    Shrikhande, S.V.; Patil, V.K.; Ganesh, G.; Biswas, B.; Patil, R.K.

    2010-01-01

    Computer Based Systems (CBS) are employed in Indian nuclear plants for protection, control and monitoring purpose. For forthcoming CBS, Reactor Control Division has designed and developed a new standardized family of microcomputer boards qualified to stringent requirements of nuclear industry. These boards form the basic building blocks of CBS. Reliability analysis of these boards is being carried out using analysis package based on MIL-STD-217Plus methodology. The estimated failure rate values of these standardized microcomputer boards will be useful for reliability assessment of these systems. The paper presents reliability analysis of microcomputer boards and case study of a CBS system built using these boards. (author)

  10. Reliability Analysis Of Fire System On The Industry Facility By Use Fameca Method

    International Nuclear Information System (INIS)

    Sony T, D.T.; Situmorang, Johnny; Ismu W, Puradwi; Demon H; Mulyanto, Dwijo; Kusmono, Slamet; Santa, Sigit Asmara

    2000-01-01

    FAMECA is one of the analysis method to determine system reliability on the industry facility. Analysis is done by some procedure that is identification of component function, determination of failure mode, severity level and effect of their failure. Reliability value is determined by three combinations that is severity level, component failure value and critical component. Reliability of analysis has been done for fire system on the industry by FAMECA method. Critical component which identified is pump, air release valve, check valve, manual test valve, isolation valve, control system etc

  11. An algorithm for reliability analysis of phased-mission systems

    International Nuclear Information System (INIS)

    Ma, Y.; Trivedi, K.S.

    1999-01-01

    The purpose of this paper is to describe an efficient Boolean algebraic algorithm that provides exact solution to the unreliability of a multi-phase mission system where the configurations are described through fault trees. The algorithm extends and improves the Boolean method originally proposed by Somani and Trivedi. By using the Boolean algebraic method, we provide an efficient modeling approach which avoids the state space explosion and the mapping problems that are encountered by the Markov chain approach. To calculate the exact solution of the phased-mission system with deterministic phase durations, we introduce the sum of disjoint phase products (SDPP) formula, which is a phased-extension of the sum of disjoint products (SDP) formula. Computationally, the algorithm is quite efficient because it calls an SDP generation algorithm in the early stage of the SDPP computation. In this way, the phase products generated in the early stage of the SDPP formula are guaranteed to be disjoint. Consequently, the number of the intermediate phase products is greatly reduced. In this paper, we also consider the transient analysis of the phased-mission system. Special care is needed to account for the possible latent failures at the mission phase change times. If there are more stringent success criteria just after a mission phase change time, an unreliability jump would occur at that time. Finally, the algorithm has been implemented in the software package SHARPE. With SHARPE, the complexities of the phased-mission system is made transparent to the potential users. The user can conveniently specify a phased-mission model at a high level (through fault trees) and analyze the system quantitatively

  12. Acquisition and statistical analysis of reliability data for I and C parts in plant protection system

    Energy Technology Data Exchange (ETDEWEB)

    Lim, T. J.; Byun, S. S.; Han, S. H.; Lee, H. J.; Lim, J. S.; Oh, S. J.; Park, K. Y.; Song, H. S. [Soongsil Univ., Seoul (Korea)

    2001-04-01

    This project has been performed in order to construct I and C part reliability databases for detailed analysis of plant protection system and to develop a methodology for analysing trip set point drifts. Reliability database for the I and C parts of plant protection system is required to perform the detailed analysis. First, we have developed an electronic part reliability prediction code based on MIL-HDBK-217F. Then we have collected generic reliability data for the I and C parts in plant protection system. Statistical analysis procedure has been developed to process the data. Then the generic reliability database has been constructed. We have also collected plant specific reliability data for the I and C parts in plant protection system for YGN 3,4 and UCN 3,4 units. Plant specific reliability database for I and C parts has been developed by the Bayesian procedure. We have also developed an statistical analysis procedure for set point drift, and performed analysis of drift effects for trip set point. The basis for the detailed analysis can be provided from the reliability database for the PPS I and C parts. The safety of the KSNP and succeeding NPPs can be proved by reducing the uncertainty of PSA. Economic and efficient operation of NPP can be possible by optimizing the test period to reduce utility's burden. 14 refs., 215 figs., 137 tabs. (Author)

  13. Constellation Ground Systems Launch Availability Analysis: Enhancing Highly Reliable Launch Systems Design

    Science.gov (United States)

    Gernand, Jeffrey L.; Gillespie, Amanda M.; Monaghan, Mark W.; Cummings, Nicholas H.

    2010-01-01

    Success of the Constellation Program's lunar architecture requires successfully launching two vehicles, Ares I/Orion and Ares V/Altair, in a very limited time period. The reliability and maintainability of flight vehicles and ground systems must deliver a high probability of successfully launching the second vehicle in order to avoid wasting the on-orbit asset launched by the first vehicle. The Ground Operations Project determined which ground subsystems had the potential to affect the probability of the second launch and allocated quantitative availability requirements to these subsystems. The Ground Operations Project also developed a methodology to estimate subsystem reliability, availability and maintainability to ensure that ground subsystems complied with allocated launch availability and maintainability requirements. The verification analysis developed quantitative estimates of subsystem availability based on design documentation; testing results, and other information. Where appropriate, actual performance history was used for legacy subsystems or comparative components that will support Constellation. The results of the verification analysis will be used to verify compliance with requirements and to highlight design or performance shortcomings for further decision-making. This case study will discuss the subsystem requirements allocation process, describe the ground systems methodology for completing quantitative reliability, availability and maintainability analysis, and present findings and observation based on analysis leading to the Ground Systems Preliminary Design Review milestone.

  14. Model of the reliability analysis of the distributed computer systems with architecture "client-server"

    Science.gov (United States)

    Kovalev, I. V.; Zelenkov, P. V.; Karaseva, M. V.; Tsarev, M. Yu; Tsarev, R. Yu

    2015-01-01

    The paper considers the problem of the analysis of distributed computer systems reliability with client-server architecture. A distributed computer system is a set of hardware and software for implementing the following main functions: processing, storage, transmission and data protection. This paper discusses the distributed computer systems architecture "client-server". The paper presents the scheme of the distributed computer system functioning represented as a graph where vertices are the functional state of the system and arcs are transitions from one state to another depending on the prevailing conditions. In reliability analysis we consider such reliability indicators as the probability of the system transition in the stopping state and accidents, as well as the intensity of these transitions. The proposed model allows us to obtain correlations for the reliability parameters of the distributed computer system without any assumptions about the distribution laws of random variables and the elements number in the system.

  15. Problems Related to Use of Some Terms in System Reliability Analysis

    Directory of Open Access Journals (Sweden)

    Nadezda Hanusova

    2004-01-01

    Full Text Available The paper deals with problems of using dependability terms, defined in actual standard STN IEC 50 (191: International electrotechnical dictionary, chap. 191: Dependability and quality of service (1993, in a technical systems dependability analysis. The goal of the paper is to find a relation between terms introduced in the mentioned standard and used in the technical systems dependability analysis and rules and practices used in a system analysis of the system theory. Description of a part of the system life cycle related to reliability is used as a starting point. The part of a system life cycle is described by the state diagram and reliability relevant therms are assigned.

  16. Probabilistic risk assessment course documentation. Volume 5. System reliability and analysis techniques Session D - quantification

    International Nuclear Information System (INIS)

    Lofgren, E.V.

    1985-08-01

    This course in System Reliability and Analysis Techniques focuses on the probabilistic quantification of accident sequences and the link between accident sequences and consequences. Other sessions in this series focus on the quantification of system reliability and the development of event trees and fault trees. This course takes the viewpoint that event tree sequences or combinations of system failures and success are available and that Boolean equations for system fault trees have been developed and are available. 93 figs., 11 tabs

  17. Reliability analysis of protection system of advanced pressurized water reactor - APR 1400

    International Nuclear Information System (INIS)

    Varde, P. V.; Choi, J. G.; Lee, D. Y.; Han, J. B.

    2003-04-01

    Reliability analysis was carried out for the protection system of the Korean Advanced Pressurized Water Reactor - APR 1400. The main focus of this study was the reliability analysis of digital protection system, however, towards giving an integrated statement of complete protection reliability an attempt has been made to include the shutdown devices and other related aspects based on the information available to date. The sensitivity analysis has been carried out for the critical components / functions in the system. Other aspects like importance analysis and human error reliability for the critical human actions form part of this work. The framework provided by this study and the results obtained shows that this analysis has potential to be utilized as part of risk informed approach for future design / regulatory applications

  18. Using reliability analysis to support decision making\\ud in phased mission systems

    OpenAIRE

    Zhang, Yang; Prescott, Darren

    2017-01-01

    Due to the environments in which they will operate, future autonomous systems must be capable of reconfiguring quickly and safely following faults or environmental changes. Past research has shown how, by considering autonomous systems to perform phased missions, reliability analysis can support decision making by allowing comparison of the probability of success of different missions following reconfiguration. Binary Decision Diagrams (BDDs) offer fast, accurate reliability analysis that cou...

  19. Mechanical system reliability analysis using a combination of graph theory and Boolean function

    International Nuclear Information System (INIS)

    Tang, J.

    2001-01-01

    A new method based on graph theory and Boolean function for assessing reliability of mechanical systems is proposed. The procedure for this approach consists of two parts. By using the graph theory, the formula for the reliability of a mechanical system that considers the interrelations of subsystems or components is generated. Use of the Boolean function to examine the failure interactions of two particular elements of the system, followed with demonstrations of how to incorporate such failure dependencies into the analysis of larger systems, a constructive algorithm for quantifying the genuine interconnections between the subsystems or components is provided. The combination of graph theory and Boolean function provides an effective way to evaluate the reliability of a large, complex mechanical system. A numerical example demonstrates that this method an effective approaches in system reliability analysis

  20. Reliable systems - Fault tree analysis via Markov reward automata

    NARCIS (Netherlands)

    Guck, Dennis

    2017-01-01

    Today’s society is characterised by the ubiquitousness of hardware and software systems on which we rely on day in, day out. They reach from transportation systems like cars, trains and planes over medical devices at a hospital to nuclear power plants. Moreover, we can observe a trend of automation

  1. Analysis and Application of Mechanical System Reliability Model Based on Copula Function

    Directory of Open Access Journals (Sweden)

    An Hai

    2016-10-01

    Full Text Available There is complicated correlations in mechanical system. By using the advantages of copula function to solve the related issues, this paper proposes the mechanical system reliability model based on copula function. And makes a detailed research for the serial and parallel mechanical system model and gets their reliability function respectively. Finally, the application research is carried out for serial mechanical system reliability model to prove its validity by example. Using Copula theory to make mechanical system reliability modeling and its expectation, studying the distribution of the random variables (marginal distribution of the mechanical product’ life and associated structure of variables separately, can reduce the difficulty of multivariate probabilistic modeling and analysis to make the modeling and analysis process more clearly.

  2. Reliability Analysis of Converter Topologies for Photovoltaic System Inverter

    OpenAIRE

    Omede, Emmanuel Ayegba

    2015-01-01

    Application of PV systems in distributed generation (DG) and as renewable sources in the power grid are gaining wide acceptance being favoured by rapid technology development, crave for alternative clean energy, environmental protection awareness, favourable energy policies, regulation and incentives. The power conversion stage of PV systems are considered important components for interfacing, transforming and adapting power from PV to end users and as such, the power quality, efficiency and ...

  3. Small nuclear power reactor emergency electric power supply system reliability comparative analysis

    International Nuclear Information System (INIS)

    Bonfietti, Gerson

    2003-01-01

    This work presents an analysis of the reliability of the emergency power supply system, of a small size nuclear power reactor. Three different configurations are investigated and their reliability analyzed. The fault tree method is used as the main tool of analysis. The work includes a bibliographic review of emergency diesel generator reliability and a discussion of the design requirements applicable to emergency electrical systems. The influence of common cause failure influences is considered using the beta factor model. The operator action is considered using human failure probabilities. A parametric analysis shows the strong dependence between the reactor safety and the loss of offsite electric power supply. It is also shown that common cause failures can be a major contributor to the system reliability. (author)

  4. Report on the analysis of field data relating to the reliability of solar hot water systems.

    Energy Technology Data Exchange (ETDEWEB)

    Menicucci, David F. (Building Specialists, Inc., Albuquerque, NM)

    2011-07-01

    Utilities are overseeing the installations of thousand of solar hot water (SHW) systems. Utility planners have begun to ask for quantitative measures of the expected lifetimes of these systems so that they can properly forecast their loads. This report, which augments a 2009 reliability analysis effort by Sandia National Laboratories (SNL), addresses this need. Additional reliability data have been collected, added to the existing database, and analyzed. The results are presented. Additionally, formal reliability theory is described, including the bathtub curve, which is the most common model to characterize the lifetime reliability character of systems, and for predicting failures in the field. Reliability theory is used to assess the SNL reliability database. This assessment shows that the database is heavily weighted with data that describe the reliability of SHW systems early in their lives, during the warranty period. But it contains few measured data to describe the ends of SHW systems lives. End-of-life data are the most critical ones to define sufficiently the reliability of SHW systems in order to answer the questions that the utilities pose. Several ideas are presented for collecting the required data, including photometric analysis of aerial photographs of installed collectors, statistical and neural network analysis of energy bills from solar homes, and the development of simple algorithms to allow conventional SHW controllers to announce system failures and record the details of the event, similar to how aircraft black box recorders perform. Some information is also presented about public expectations for the longevity of a SHW system, information that is useful in developing reliability goals.

  5. Analysis of the reliability of the active injection safety systems of Angra I

    International Nuclear Information System (INIS)

    Frutuoso e Melo, P.F.F.

    1981-01-01

    The reliability of the active emergency core cooling systems of Angra I nuclear power plant is evaluated. The fault tree analysis is employed. The unavailability of the above cited systems, is calculated. A parametric sensitivity analysis has been performed, due to the existing scattering in the failure and repair rate data of these system's components. The minimal cut sets were determined and, as a final step, a reliability importance analysis has been performed. This final step has required the development of a computer program. The methodology and data from the 'Reactor Safety Study' (Wash-1400) (in which the reliability of safety systems of a tipical PWR plant is calculated), is employed. The unavailability values for the safety systems analysed are too low, thus showing that in most cases the systems analysed are available to mitigate the effects of a loss-of-coolant accident. (Author) [pt

  6. 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...

  7. The application of emulation techniques in the analysis of highly reliable, guidance and control computer systems

    Science.gov (United States)

    Migneault, Gerard E.

    1987-01-01

    Emulation techniques can be a solution to a difficulty that arises in the analysis of the reliability of guidance and control computer systems for future commercial aircraft. Described here is the difficulty, the lack of credibility of reliability estimates obtained by analytical modeling techniques. The difficulty is an unavoidable consequence of the following: (1) a reliability requirement so demanding as to make system evaluation by use testing infeasible; (2) a complex system design technique, fault tolerance; (3) system reliability dominated by errors due to flaws in the system definition; and (4) elaborate analytical modeling techniques whose precision outputs are quite sensitive to errors of approximation in their input data. Use of emulation techniques for pseudo-testing systems to evaluate bounds on the parameter values needed for the analytical techniques is then discussed. Finally several examples of the application of emulation techniques are described.

  8. Reliability analysis of hierarchical computer-based systems subject to common-cause failures

    International Nuclear Information System (INIS)

    Xing Liudong; Meshkat, Leila; Donohue, Susan K.

    2007-01-01

    The results from reliability modeling and analysis are key contributors to design and tuning activities for computer-based systems. Each architecture style, however, poses different challenges for which analytical approaches must be developed or modified. The challenge we address in this paper is the reliability analysis of hierarchical computer-based systems (HS) with common-cause failures (CCF). The dependencies among components introduced by CCF complicate the reliability analysis of HS, especially when components affected by a common cause exist on different hierarchical levels. We propose an efficient decomposition and aggregation (EDA) approach for incorporating CCF into the reliability evaluation of HS. Our approach is to decompose an original HS reliability analysis problem with CCF into a number of reduced reliability problems freed from the CCF concerns. The approach is represented in a dynamic fault tree by a proposed CCF gate modeled after the functional dependency gate. We present the basics of the EDA approach by working through a hypothetical analysis of a HS subject to CCF and show how it can be extended to an analysis of a hierarchical phased-mission system subject to different CCF depending on mission phases

  9. Reliability analysis for power supply system in a reprocessing facility based on GO methodology

    International Nuclear Information System (INIS)

    Wang Renze

    2014-01-01

    GO methodology was applied to analyze the reliability of power supply system in a typical reprocessing facility. Based on the fact that tie breakers are set in the system, tie breaker operator was defined. Then GO methodology modeling and quantitative analysis were performed sequently, minimal cut sets and average unavailability of the system were obtained. Parallel analysis between GO methodology and fault tree methodology was also performed. The results showed that setup of tie breakers was rational and necessary and that the modeling was much easier and the chart was much more succinct for GO methodology parallel with fault tree methodology to analyze the reliability of the power supply system. (author)

  10. Requirements for reliability analysis of safety-related systems in nuclear reactors

    International Nuclear Information System (INIS)

    1987-01-01

    This document defines general principles for reliability analyses of safety-related systems in nuclear reactors. Reliability analysis should be part of a process that starts early in the design stage and continues throughout the operating life of the analyzed system. It shall be consistent with the detailed design requirements of the system and shall address all permissible modes of operation of the system. Boundaries between systems and subsystems must be clearly defined. Analyses of connected systems shall be consistent with each other. Reliability analyses shall be consistent with the approved plant design and operating procedures in accordance with information available at the date of the report. A procedure shall be established for determining the changes between the information used in the analysis and the current status. (L.L.)

  11. Reliable computer systems.

    Science.gov (United States)

    Wear, L L; Pinkert, J R

    1993-11-01

    In this article, we looked at some decisions that apply to the design of reliable computer systems. We began with a discussion of several terms such as testability, then described some systems that call for highly reliable hardware and software. The article concluded with a discussion of methods that can be used to achieve higher reliability in computer systems. Reliability and fault tolerance in computers probably will continue to grow in importance. As more and more systems are computerized, people will want assurances about the reliability of these systems, and their ability to work properly even when sub-systems fail.

  12. Reliability analysis of idealized tunnel support system using probability-based methods with case studies

    Science.gov (United States)

    Gharouni-Nik, Morteza; Naeimi, Meysam; Ahadi, Sodayf; Alimoradi, Zahra

    2014-06-01

    In order to determine the overall safety of a tunnel support lining, a reliability-based approach is presented in this paper. Support elements in jointed rock tunnels are provided to control the ground movement caused by stress redistribution during the tunnel drive. Main support elements contribute to stability of the tunnel structure are recognized owing to identify various aspects of reliability and sustainability in the system. The selection of efficient support methods for rock tunneling is a key factor in order to reduce the number of problems during construction and maintain the project cost and time within the limited budget and planned schedule. This paper introduces a smart approach by which decision-makers will be able to find the overall reliability of tunnel support system before selecting the final scheme of the lining system. Due to this research focus, engineering reliability which is a branch of statistics and probability is being appropriately applied to the field and much effort has been made to use it in tunneling while investigating the reliability of the lining support system for the tunnel structure. Therefore, reliability analysis for evaluating the tunnel support performance is the main idea used in this research. Decomposition approaches are used for producing system block diagram and determining the failure probability of the whole system. Effectiveness of the proposed reliability model of tunnel lining together with the recommended approaches is examined using several case studies and the final value of reliability obtained for different designing scenarios. Considering the idea of linear correlation between safety factors and reliability parameters, the values of isolated reliabilities determined for different structural components of tunnel support system. In order to determine individual safety factors, finite element modeling is employed for different structural subsystems and the results of numerical analyses are obtained in

  13. Integrating reliability analysis and design

    International Nuclear Information System (INIS)

    Rasmuson, D.M.

    1980-10-01

    This report describes the Interactive Reliability Analysis Project and demonstrates the advantages of using computer-aided design systems (CADS) in reliability analysis. Common cause failure problems require presentations of systems, analysis of fault trees, and evaluation of solutions to these. Results have to be communicated between the reliability analyst and the system designer. Using a computer-aided design system saves time and money in the analysis of design. Computer-aided design systems lend themselves to cable routing, valve and switch lists, pipe routing, and other component studies. At EG and G Idaho, Inc., the Applicon CADS is being applied to the study of water reactor safety systems

  14. Living PRAs [probabilistic risk analysis] made easier with IRRAS [Integrated Reliability and Risk Analysis System

    International Nuclear Information System (INIS)

    Russell, K.D.; Sattison, M.B.; Rasmuson, D.M.

    1989-01-01

    The Integrated Reliability and Risk Analysis System (IRRAS) is an integrated PRA software tool that gives the user the ability to create and analyze fault trees and accident sequences using an IBM-compatible microcomputer. This program provides functions that range from graphical fault tree and event tree construction to cut set generation and quantification. IRRAS contains all the capabilities and functions required to create, modify, reduce, and analyze event tree and fault tree models used in the analysis of complex systems and processes. IRRAS uses advanced graphic and analytical techniques to achieve the greatest possible realization of the potential of the microcomputer. When the needs of the user exceed this potential, IRRAS can call upon the power of the mainframe computer. The role of the Idaho National Engineering Laboratory if the IRRAS program is that of software developer and interface to the user community. Version 1.0 of the IRRAS program was released in February 1987 to prove the concept of performing this kind of analysis on microcomputers. This version contained many of the basic features needed for fault tree analysis and was received very well by the PRA community. Since the release of Version 1.0, many user comments and enhancements have been incorporated into the program providing a much more powerful and user-friendly system. This version is designated ''IRRAS 2.0''. Version 3.0 will contain all of the features required for efficient event tree and fault tree construction and analysis. 5 refs., 26 figs

  15. Guidelines for reliability analysis of digital systems in PSA context. Phase 1 status report

    International Nuclear Information System (INIS)

    Authen, S.; Larsson, J.; Bjoerkman, K.; Holmberg, J.-E.

    2010-12-01

    Digital protection and control systems are appearing as upgrades in older nuclear power plants (NPPs) and are commonplace in new NPPs. To assess the risk of NPP operation and to determine the risk impact of digital system upgrades on NPPs, quantitative reliability models are needed for digital systems. Due to the many unique attributes of these systems, challenges exist in systems analysis, modeling and in data collection. Currently there is no consensus on reliability analysis approaches. Traditional methods have clearly limitations, but more dynamic approaches are still in trial stage and can be difficult to apply in full scale probabilistic safety assessments (PSA). The number of PSAs worldwide including reliability models of digital I and C systems are few. A comparison of Nordic experiences and a literature review on main international references have been performed in this pre-study project. The study shows a wide range of approaches, and also indicates that no state-of-the-art currently exists. The study shows areas where the different PSAs agree and gives the basis for development of a common taxonomy for reliability analysis of digital systems. It is still an open matter whether software reliability needs to be explicitly modelled in the PSA. The most important issue concerning software reliability is proper descriptions of the impact that software-based systems has on the dependence between the safety functions and the structure of accident sequences. In general the conventional fault tree approach seems to be sufficient for modelling reactor protection system kind of functions. The following focus areas have been identified for further activities: 1. Common taxonomy of hardware and software failure modes of digital components for common use 2. Guidelines regarding level of detail in system analysis and screening of components, failure modes and dependencies 3. Approach for modelling of CCF between components (including software). (Author)

  16. Guidelines for reliability analysis of digital systems in PSA context. Phase 1 status report

    Energy Technology Data Exchange (ETDEWEB)

    Authen, S.; Larsson, J. (Risk Pilot AB, Stockholm (Sweden)); Bjoerkman, K.; Holmberg, J.-E. (VTT, Helsingfors (Finland))

    2010-12-15

    Digital protection and control systems are appearing as upgrades in older nuclear power plants (NPPs) and are commonplace in new NPPs. To assess the risk of NPP operation and to determine the risk impact of digital system upgrades on NPPs, quantitative reliability models are needed for digital systems. Due to the many unique attributes of these systems, challenges exist in systems analysis, modeling and in data collection. Currently there is no consensus on reliability analysis approaches. Traditional methods have clearly limitations, but more dynamic approaches are still in trial stage and can be difficult to apply in full scale probabilistic safety assessments (PSA). The number of PSAs worldwide including reliability models of digital I and C systems are few. A comparison of Nordic experiences and a literature review on main international references have been performed in this pre-study project. The study shows a wide range of approaches, and also indicates that no state-of-the-art currently exists. The study shows areas where the different PSAs agree and gives the basis for development of a common taxonomy for reliability analysis of digital systems. It is still an open matter whether software reliability needs to be explicitly modelled in the PSA. The most important issue concerning software reliability is proper descriptions of the impact that software-based systems has on the dependence between the safety functions and the structure of accident sequences. In general the conventional fault tree approach seems to be sufficient for modelling reactor protection system kind of functions. The following focus areas have been identified for further activities: 1. Common taxonomy of hardware and software failure modes of digital components for common use 2. Guidelines regarding level of detail in system analysis and screening of components, failure modes and dependencies 3. Approach for modelling of CCF between components (including software). (Author)

  17. Suitability review of FMEA and reliability analysis for digital plant protection system and digital engineered safety features actuation system

    Energy Technology Data Exchange (ETDEWEB)

    Kim, I. S.; Kim, T. K.; Kim, M. C.; Kim, B. S.; Hwang, S. W.; Ryu, K. C. [Hanyang Univ., Seoul (Korea, Republic of)

    2000-11-15

    Of the many items that should be checked out during a review stage of the licensing application for the I and C system of Ulchin 5 and 6 units, this report relates to a suitability review of the reliability analysis of Digital Plant Protection System (DPPS) and Digital Engineered Safety Features Actuation System (DESFAS). In the reliability analysis performed by the system designer, ABB-CE, fault tree analysis was used as the main methods along with Failure Modes and Effect Analysis (FMEA). However, the present regulatory technique dose not allow the system reliability analysis and its results to be appropriately evaluated. Hence, this study was carried out focusing on the following four items ; development of general review items by which to check the validity of a reliability analysis, and the subsequent review of suitability of the reliability analysis for Ulchin 5 and 6 DPPS and DESFAS L development of detailed review items by which to check the validity of an FMEA, and the subsequent review of suitability of the FMEA for Ulchin 5 and 6 DPPS and DESFAS ; development of detailed review items by which to check the validity of a fault tree analysis, and the subsequent review of suitability of the fault tree for Ulchin 5 and 6 DPPS and DESFAS ; an integrated review of the safety and reliability of the Ulchin 5 and 6 DPPS and DESFAS based on the results of the various reviews above and also of a reliability comparison between the digital systems and the comparable analog systems, i.e., and analog Plant Protection System (PPS) and and analog Engineered Safety Features Actuation System (ESFAS). According to the review mentioned above, the reliability analysis of Ulchin 5 and 6 DPPS and DESFAS generally satisfies the review requirements. However, some shortcomings of the analysis were identified in our review such that the assumed test periods for several equipment were not properly incorporated in the analysis, and failures of some equipment were not included in the

  18. Latency Analysis of Systems with Multiple Interfaces for Ultra-Reliable M2M Communication

    DEFF Research Database (Denmark)

    Nielsen, Jimmy Jessen; Popovski, Petar

    2016-01-01

    One of the ways to satisfy the requirements of ultra-reliable low latency communication for mission critical Machine-type Communications (MTC) applications is to integrate multiple communication interfaces. In order to estimate the performance in terms of latency and reliability of such an integr......One of the ways to satisfy the requirements of ultra-reliable low latency communication for mission critical Machine-type Communications (MTC) applications is to integrate multiple communication interfaces. In order to estimate the performance in terms of latency and reliability...... of such an integrated communication system, we propose an analysis framework that combines traditional reliability models with technology-specific latency probability distributions. In our proposed model we demonstrate how failure correlation between technologies can be taken into account. We show for the considered...

  19. 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

  20. Efficient surrogate models for reliability analysis of systems with multiple failure modes

    International Nuclear Information System (INIS)

    Bichon, Barron J.; McFarland, John M.; Mahadevan, Sankaran

    2011-01-01

    Despite many advances in the field of computational reliability analysis, the efficient estimation of the reliability of a system with multiple failure modes remains a persistent challenge. Various sampling and analytical methods are available, but they typically require accepting a tradeoff between accuracy and computational efficiency. In this work, a surrogate-based approach is presented that simultaneously addresses the issues of accuracy, efficiency, and unimportant failure modes. The method is based on the creation of Gaussian process surrogate models that are required to be locally accurate only in the regions of the component limit states that contribute to system failure. This approach to constructing surrogate models is demonstrated to be both an efficient and accurate method for system-level reliability analysis. - Highlights: → Extends efficient global reliability analysis to systems with multiple failure modes. → Constructs locally accurate Gaussian process models of each response. → Highly efficient and accurate method for assessing system reliability. → Effectiveness is demonstrated on several test problems from the literature.

  1. Reliability analysis of Markov history-dependent repairable systems with neglected failures

    International Nuclear Information System (INIS)

    Du, Shijia; Zeng, Zhiguo; Cui, Lirong; Kang, Rui

    2017-01-01

    Markov history-dependent repairable systems refer to the Markov repairable systems in which some states are changeable and dependent on recent evolutional history of the system. In practice, many Markov history-dependent repairable systems are subjected to neglected failures, i.e., some failures do not affect system performances if they can be repaired promptly. In this paper, we develop a model based on the theory of aggregated stochastic processes to describe the history-dependent behavior and the effect of neglected failures on the Markov history-dependent repairable systems. Based on the developed model, instantaneous and steady-state availabilities are derived to characterize the reliability of the system. Four reliability-related time distributions, i.e., distribution for the k th working period, distribution for the k th failure period, distribution for the real working time in an effective working period, distribution for the neglected failure time in an effective working period, are also derived to provide a more comprehensive description of the system's reliability. Thanks to the power of the theory of aggregated stochastic processes, closed-form expressions are obtained for all the reliability indexes and time distributions. Finally, the developed indexes and analysis methods are demonstrated by a numerical example. - Highlights: • Markovian history-dependent repairable systems with neglected failures is modeled. • Aggregated stochastic processes are used to derive reliability indexes and time distributions. • Closed-form expressions are derived for the considered indexes and distributions.

  2. Reliability analysis and optimisation of subsea compression system facing operational covariate stresses

    International Nuclear Information System (INIS)

    Okaro, Ikenna Anthony; Tao, Longbin

    2016-01-01

    This paper proposes an enhanced Weibull-Corrosion Covariate model for reliability assessment of a system facing operational stresses. The newly developed model is applied to a Subsea Gas Compression System planned for offshore West Africa to predict its reliability index. System technical failure was modelled by developing a Weibull failure model incorporating a physically tested corrosion profile as stress in order to quantify the survival rate of the system under additional operational covariates including marine pH, temperature and pressure. Using Reliability Block Diagrams and enhanced Fusell-Vesely formulations, the whole system was systematically decomposed to sub-systems to analyse the criticality of each component and optimise them. Human reliability was addressed using an enhanced barrier weighting method. A rapid degradation curve is obtained on a subsea system relative to the base case subjected to a time-dependent corrosion stress factor. It reveals that subsea system components failed faster than their Mean time to failure specifications from Offshore Reliability Database as a result of cumulative marine stresses exertion. The case study demonstrated that the reliability of a subsea system can be systematically optimised by modelling the system under higher technical and organisational stresses, prioritising the critical sub-systems and making befitting provisions for redundancy and tolerances. - Highlights: • Novel Weibull Corrosion-Covariate model for reliability analysis of subsea assets. • Predict the accelerated degradation profile of a subsea gas compression. • An enhanced optimisation method based on Fusell-Vesely decomposition process. • New optimisation approach for smoothening of over- and under-designed components. • Demonstrated a significant improvement in producing more realistic failure rate.

  3. Enforsing a system approach to composite failure criteria for reliability analysis

    DEFF Research Database (Denmark)

    Dimitrov, Nikolay Krasimirov; Friis-Hansen, Peter; Berggreen, Christian

    2011-01-01

    parameters are random, multiple failure modes may be identified which will jeopardize the FORM analysis and a system approach should be applied to assure a correct analysis. Although crude Monte Carlo simulation automatically may account for such effects, time constraints limit its useability in problems......Composite failure criteria have found widespread use in research and industry. In the vast majority of applications the material properties and the stresses, which serve as inputs to the criteria, are defined deterministically. However, when the reliability of composite structures is sought...... the input to the failure criterion will be random quantities. The reliability is efficiently identified using approximate methods such as First Order Reliability Methods (FORM) [1,2]. FORM involves an iterative optimization procedure to obtain a reliability estimate, which imposes a number of additional...

  4. System reliability assessment via sensitivity analysis in the Markov chain scheme

    International Nuclear Information System (INIS)

    Gandini, A.

    1988-01-01

    Methods for reliability sensitivity analysis in the Markov chain scheme are presented, together with a new formulation which makes use of Generalized Perturbation Theory (GPT) methods. As well known, sensitivity methods are fundamental in system risk analysis, since they allow to identify important components, so to assist the analyst in finding weaknesses in design and operation and in suggesting optimal modifications for system upgrade. The relationship between the GPT sensitivity expression and the Birnbaum importance is also given [fr

  5. Advanced reactor passive system reliability demonstration analysis for an external event

    International Nuclear Information System (INIS)

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

    2017-01-01

    Many advanced reactor designs rely on passive systems to fulfill safety functions during accident sequences. These systems depend heavily on boundary conditions to induce a motive force, meaning the system can fail to operate as intended because of deviations in boundary conditions, rather than as the result of physical failures. Furthermore, passive systems may operate in intermediate or degraded modes. These factors make passive system operation difficult to characterize within a traditional probabilistic framework that only recognizes discrete operating modes and does not allow for the explicit consideration of time-dependent boundary conditions. Argonne National Laboratory has been examining various methodologies for assessing passive system reliability within a probabilistic risk assessment for a station blackout event at an advanced small modular reactor. This paper provides an overview of a passive system reliability demonstration analysis for an external event. Considering an earthquake with the possibility of site flooding, the analysis focuses on the behavior of the passive Reactor Cavity Cooling System following potential physical damage and system flooding. The assessment approach seeks to combine mechanistic and simulation-based methods to leverage the benefits of the simulation-based approach without the need to substantially deviate from conventional probabilistic risk assessment techniques. Although this study is presented as only an example analysis, the results appear to demonstrate a high level of reliability of the Reactor Cavity Cooling System (and the reactor system in general) for the postulated transient event

  6. Advanced reactor passive system reliability demonstration analysis for an external event

    Energy Technology Data Exchange (ETDEWEB)

    Bucknor, Matthew; Grabaskas, David; Brunett, Acacia J.; Grelle, Austin [Argonne National Laboratory, Argonne (United States)

    2017-03-15

    Many advanced reactor designs rely on passive systems to fulfill safety functions during accident sequences. These systems depend heavily on boundary conditions to induce a motive force, meaning the system can fail to operate as intended because of deviations in boundary conditions, rather than as the result of physical failures. Furthermore, passive systems may operate in intermediate or degraded modes. These factors make passive system operation difficult to characterize within a traditional probabilistic framework that only recognizes discrete operating modes and does not allow for the explicit consideration of time-dependent boundary conditions. Argonne National Laboratory has been examining various methodologies for assessing passive system reliability within a probabilistic risk assessment for a station blackout event at an advanced small modular reactor. This paper provides an overview of a passive system reliability demonstration analysis for an external event. Considering an earthquake with the possibility of site flooding, the analysis focuses on the behavior of the passive Reactor Cavity Cooling System following potential physical damage and system flooding. The assessment approach seeks to combine mechanistic and simulation-based methods to leverage the benefits of the simulation-based approach without the need to substantially deviate from conventional probabilistic risk assessment techniques. Although this study is presented as only an example analysis, the results appear to demonstrate a high level of reliability of the Reactor Cavity Cooling System (and the reactor system in general) for the postulated transient event.

  7. Advanced Reactor Passive System Reliability Demonstration Analysis for an External Event

    Directory of Open Access Journals (Sweden)

    Matthew Bucknor

    2017-03-01

    Full Text Available Many advanced reactor designs rely on passive systems to fulfill safety functions during accident sequences. These systems depend heavily on boundary conditions to induce a motive force, meaning the system can fail to operate as intended because of deviations in boundary conditions, rather than as the result of physical failures. Furthermore, passive systems may operate in intermediate or degraded modes. These factors make passive system operation difficult to characterize within a traditional probabilistic framework that only recognizes discrete operating modes and does not allow for the explicit consideration of time-dependent boundary conditions. Argonne National Laboratory has been examining various methodologies for assessing passive system reliability within a probabilistic risk assessment for a station blackout event at an advanced small modular reactor. This paper provides an overview of a passive system reliability demonstration analysis for an external event. Considering an earthquake with the possibility of site flooding, the analysis focuses on the behavior of the passive Reactor Cavity Cooling System following potential physical damage and system flooding. The assessment approach seeks to combine mechanistic and simulation-based methods to leverage the benefits of the simulation-based approach without the need to substantially deviate from conventional probabilistic risk assessment techniques. Although this study is presented as only an example analysis, the results appear to demonstrate a high level of reliability of the Reactor Cavity Cooling System (and the reactor system in general for the postulated transient event.

  8. Intra-rater and inter-rater reliabilities of real-time acceleration gait analysis system.

    Science.gov (United States)

    Osaka, Hiroshi; Shinkoda, Koichi; Watanabe, Susumu; Fujita, Daisuke; Kobara, Kenichi; Yoshimura, Yosuke; Ito, Tomotaka

    2016-01-01

    The purposes of this study were to construct a real-time acceleration gait analysis system equipped with software to analyse real-time trunk acceleration during walking and to examine the intra-rater and inter-rater reliabilities of the this system. This system has been comprised of an accelerometer, an acceleration amplifier, a transmitter, two foot switches, a receiver and a personal computer installed with the real-time acceleration analysis software. The acceleration signals received were analysed using the real-time acceleration analysis software, and gait parameters were calculated. The subjects were 20 healthy individuals and two raters. The intra-rater and inter-rater reliabilities of the measurement results obtained from this system were examined by performing intraclass correlation coefficients (ICC) and Bland-Altman analysis. The intra-rater and inter-rater ICCs ranged from 0.61 to 0.92 in any gait parameters. In the Bland-Altman analysis, neither fixed nor proportional bias was found in any of the gait parameters. From the ICC and Bland-Altman analysis results, the gait measurement using this system clearly demonstrates that the intra-rater and inter-rater measurements had good reproducibility. Owing to this system, we can improve the clinical efficiency of gait analysis and gait training for physiotherapy. Implication for Rehabilitation This study focused on the advantage of a gait analysis method using an accelerometer and constructed a gait analysis system that calculates real-time gait parameters from trunk acceleration measurements during walking. The gait analysis using this system has good intra-rater and inter-rater reliabilities, and using this system can improve the clinical efficiency of gait analysis and gait training.

  9. A Report on Simulation-Driven Reliability and Failure Analysis of Large-Scale Storage Systems

    Energy Technology Data Exchange (ETDEWEB)

    Wan, Lipeng [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Wang, Feiyi [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Oral, H. Sarp [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Vazhkudai, Sudharshan S. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Cao, Qing [Univ. of Tennessee, Knoxville, TN (United States)

    2014-11-01

    High-performance computing (HPC) storage systems provide data availability and reliability using various hardware and software fault tolerance techniques. Usually, reliability and availability are calculated at the subsystem or component level using limited metrics such as, mean time to failure (MTTF) or mean time to data loss (MTTDL). This often means settling on simple and disconnected failure models (such as exponential failure rate) to achieve tractable and close-formed solutions. However, such models have been shown to be insufficient in assessing end-to-end storage system reliability and availability. We propose a generic simulation framework aimed at analyzing the reliability and availability of storage systems at scale, and investigating what-if scenarios. The framework is designed for an end-to-end storage system, accommodating the various components and subsystems, their interconnections, failure patterns and propagation, and performs dependency analysis to capture a wide-range of failure cases. We evaluate the framework against a large-scale storage system that is in production and analyze its failure projections toward and beyond the end of lifecycle. We also examine the potential operational impact by studying how different types of components affect the overall system reliability and availability, and present the preliminary results

  10. The violent crime linkage analysis system: A test of interrater reliability

    NARCIS (Netherlands)

    Snook, B.; Luther, K.; House, J. C.; Bennell, C.; Taylor, Paul J

    2012-01-01

    The interrater reliability of an internationally renowned crime linkage system—the Violent Crime Linkage Analysis System (ViCLAS)—was tested. Police officers (N = 10) were presented with a case file and asked to complete a ViCLAS booklet. The level of occurrence agreement between each officer was

  11. System reliability analysis using dominant failure modes identified by selective searching technique

    International Nuclear Information System (INIS)

    Kim, Dong-Seok; Ok, Seung-Yong; Song, Junho; Koh, Hyun-Moo

    2013-01-01

    The failure of a redundant structural system is often described by innumerable system failure modes such as combinations or sequences of local failures. An efficient approach is proposed to identify dominant failure modes in the space of random variables, and then perform system reliability analysis to compute the system failure probability. To identify dominant failure modes in the decreasing order of their contributions to the system failure probability, a new simulation-based selective searching technique is developed using a genetic algorithm. The system failure probability is computed by a multi-scale matrix-based system reliability (MSR) method. Lower-scale MSR analyses evaluate the probabilities of the identified failure modes and their statistical dependence. A higher-scale MSR analysis evaluates the system failure probability based on the results of the lower-scale analyses. Three illustrative examples demonstrate the efficiency and accuracy of the approach through comparison with existing methods and Monte Carlo simulations. The results show that the proposed method skillfully identifies the dominant failure modes, including those neglected by existing approaches. The multi-scale MSR method accurately evaluates the system failure probability with statistical dependence fully considered. The decoupling between the failure mode identification and the system reliability evaluation allows for effective applications to larger structural systems

  12. Reliability Analysis of Load-Sharing K-out-of-N System Considering Component Degradation

    Directory of Open Access Journals (Sweden)

    Chunbo Yang

    2015-01-01

    Full Text Available The K-out-of-N configuration is a typical form of redundancy techniques to improve system reliability, where at least K-out-of-N components must work for successful operation of system. When the components are degraded, more components are needed to meet the system requirement, which means that the value of K has to increase. The current reliability analysis methods overestimate the reliability, because using constant K ignores the degradation effect. In a load-sharing system with degrading components, the workload shared on each surviving component will increase after a random component failure, resulting in higher failure rate and increased performance degradation rate. This paper proposes a method combining a tampered failure rate model with a performance degradation model to analyze the reliability of load-sharing K-out-of-N system with degrading components. The proposed method considers the value of K as a variable which is derived by the performance degradation model. Also, the load-sharing effect is evaluated by the tampered failure rate model. Monte-Carlo simulation procedure is used to estimate the discrete probability distribution of K. The case of a solar panel is studied in this paper, and the result shows that the reliability considering component degradation is less than that ignoring component degradation.

  13. Reliability of fluid systems

    Directory of Open Access Journals (Sweden)

    Kopáček Jaroslav

    2016-01-01

    Full Text Available This paper focuses on the importance of detection reliability, especially in complex fluid systems for demanding production technology. The initial criterion for assessing the reliability is the failure of object (element, which is seen as a random variable and their data (values can be processed using by the mathematical methods of theory probability and statistics. They are defined the basic indicators of reliability and their applications in calculations of serial, parallel and backed-up systems. For illustration, there are calculation examples of indicators of reliability for various elements of the system and for the selected pneumatic circuit.

  14. The Reliability Analysis for Corporative IP-Telephony System with Functional Safety

    Directory of Open Access Journals (Sweden)

    A. E. Alexandrovich

    2011-06-01

    Full Text Available The article is devoted to issues of reliability modeling for fault tolerant corporative IP-telephony system. Two reliability models are presented based on the minimal paths and minimal cuts technique. Two reliability models are proposed based on the link connection concept. IP-telephony corporative system fault tolerance research is conducted with the aid of proposed reliability models.

  15. On Component Reliability and System Reliability for Space Missions

    Science.gov (United States)

    Chen, Yuan; Gillespie, Amanda M.; Monaghan, Mark W.; Sampson, Michael J.; Hodson, Robert F.

    2012-01-01

    This paper is to address the basics, the limitations and the relationship between component reliability and system reliability through a study of flight computing architectures and related avionics components for NASA future missions. Component reliability analysis and system reliability analysis need to be evaluated at the same time, and the limitations of each analysis and the relationship between the two analyses need to be understood.

  16. Operational present status and reliability analysis of the upgraded EAST cryogenic system

    Science.gov (United States)

    Zhou, Z. W.; Y Zhang, Q.; Lu, X. F.; Hu, L. B.; Zhu, P.

    2017-12-01

    Since the first commissioning in 2005, the cryogenic system for EAST (Experimental Advanced Superconducting Tokamak) has been cooled down and warmed up for thirteen experimental campaigns. In order to promote the refrigeration efficiencies and reliability, the EAST cryogenic system was upgraded gradually with new helium screw compressors and new dynamic gas bearing helium turbine expanders with eddy current brake to improve the original poor mechanical and operational performance from 2012 to 2015. Then the totally upgraded cryogenic system was put into operation in the eleventh cool-down experiment, and has been operated for the latest several experimental campaigns. The upgraded system has successfully coped with various normal operational modes during cool-down and 4.5 K steady-state operation under pulsed heat load from the tokamak as well as the abnormal fault modes including turbines protection stop. In this paper, the upgraded EAST cryogenic system including its functional analysis and new cryogenic control networks will be presented in detail. Also, its operational present status in the latest cool-down experiments will be presented and the system reliability will be analyzed, which shows a high reliability and low fault rate after upgrade. In the end, some future necessary work to meet the higher reliability requirement for future uninterrupted long-term experimental operation will also be proposed.

  17. Exact combinatorial reliability analysis of dynamic systems with sequence-dependent failures

    International Nuclear Information System (INIS)

    Xing Liudong; Shrestha, Akhilesh; Dai Yuanshun

    2011-01-01

    Many real-life fault-tolerant systems are subjected to sequence-dependent failure behavior, in which the order in which the fault events occur is important to the system reliability. Such systems can be modeled by dynamic fault trees (DFT) with priority-AND (pAND) gates. Existing approaches for the reliability analysis of systems subjected to sequence-dependent failures are typically state-space-based, simulation-based or inclusion-exclusion-based methods. Those methods either suffer from the state-space explosion problem or require long computation time especially when results with high degree of accuracy are desired. In this paper, an analytical method based on sequential binary decision diagrams is proposed. The proposed approach can analyze the exact reliability of non-repairable dynamic systems subjected to the sequence-dependent failure behavior. Also, the proposed approach is combinatorial and is applicable for analyzing systems with any arbitrary component time-to-failure distributions. The application and advantages of the proposed approach are illustrated through analysis of several examples. - Highlights: → We analyze the sequence-dependent failure behavior using combinatorial models. → The method has no limitation on the type of time-to-failure distributions. → The method is analytical and based on sequential binary decision diagrams (SBDD). → The method is computationally more efficient than existing methods.

  18. Reliability And Maintenance Analysis Of CCTV Systems Used In Rail Transport

    Directory of Open Access Journals (Sweden)

    Siergiejczyk Mirosław

    2015-11-01

    Full Text Available CCTV systems are widely used across plethora of industrial areas including transport, where their function is to support transport telematics systems. Among others, they are used to ensure travel safety. This paper presented a reliability and maintenance analysis of CCTV. It led to building a relationships graph and then Chapman–Kolmogorov system of equations was derived to describe it. Drawing on those equations, relationships for calculating probability of system staying in state of full ability SPZ, state of the impendency over safety SZB1 as well as state of unreliability of safety SB were derived.

  19. Reliability analysis of nuclear component cooling water system using semi-Markov process model

    International Nuclear Information System (INIS)

    Veeramany, Arun; Pandey, Mahesh D.

    2011-01-01

    Research highlights: → Semi-Markov process (SMP) model is used to evaluate system failure probability of the nuclear component cooling water (NCCW) system. → SMP is used because it can solve reliability block diagram with a mixture of redundant repairable and non-repairable components. → The primary objective is to demonstrate that SMP can consider Weibull failure time distribution for components while a Markov model cannot → Result: the variability in component failure time is directly proportional to the NCCW system failure probability. → The result can be utilized as an initiating event probability in probabilistic safety assessment projects. - Abstract: A reliability analysis of nuclear component cooling water (NCCW) system is carried out. Semi-Markov process model is used in the analysis because it has potential to solve a reliability block diagram with a mixture of repairable and non-repairable components. With Markov models it is only possible to assume an exponential profile for component failure times. An advantage of the proposed model is the ability to assume Weibull distribution for the failure time of components. In an attempt to reduce the number of states in the model, it is shown that usage of poly-Weibull distribution arises. The objective of the paper is to determine system failure probability under these assumptions. Monte Carlo simulation is used to validate the model result. This result can be utilized as an initiating event probability in probabilistic safety assessment projects.

  20. Reliability analysis of the reconstructed safety systems of the Kozloduy-2 WWER-440/V-230 reactor

    International Nuclear Information System (INIS)

    Kalchev, B.

    1995-01-01

    The Unit 2 of the Kozloduy NPP started operations in 1975. As it is designed according to safety standards of the middle sixties, it needs reconstruction in order to prolong its operational life up to the design age of 30 years, in agreement with the increased safety requirements in Bulgaria. The reliability analyses of front line systems of the unit are performed to this end. The approach taken in the study is the fault tree methodology to determine the unavailability of each system. Common mode failures are considered for the pumps and valves using the beta factor method. The mission time for each system is 24 hours and the test period is 720 hours. Support systems and human errors are also included. All the systems control and instrumentation signals are modelled explicitly in the fault trees. The generic IDEA reliability data base is used for all quantifications. The initiating events that would require the system operation are presented and on this basis the thermohydraulic analysis success criteria for each system are determined. The code for probabilistic safety assessment PSAPACK is used. Fault trees for the following front line safety systems are constructed: the high pressure injection system, the spray system and the auxiliary feed water system. The analysis consider some proposed decisions for reconstruction. The results show that the reliability of these systems has increased after reconstruction and the safety has been upgraded. This decrease the core damage frequency from 3.53E -3 , 1/RY to 1.07E -3 , 1/RY. 5 refs., 2 tabs., 5 figs

  1. Reliability analysis of the recirculation phase of the safety injection system of Angra-1

    International Nuclear Information System (INIS)

    Rivera, R.R.J.M.

    1981-09-01

    The calculation of several reliability parameters-failure probability, unavailability and unreliability - of the recirculation phase of the safety injection system of Angra-1, was done. This system has two distinct modes of operation (short term and long term) which were fault tree analysed both separately and as a whole. To obtain quantitative results the computer codes SAMPLE and PRET-KITT were utilized. The former was used to consider the uncertainties in the failure data (drawn integrally from WASH-1400) and the latter to obtain time dependent unreliability values. Hardware failures and common-mode failures were considered. Altough the analysis methods employed here differ somewhat from those used in WASH-1400, the results which could be compared were found to have the order of magnitude. A viability study of some suggestions of system's modifications was performed, and it has shown that some significant reliability improvements can be achieved with reasonably simple changes. (Author) [pt

  2. Reliability Analysis of a Cold Standby System with Imperfect Repair and under Poisson Shocks

    Directory of Open Access Journals (Sweden)

    Yutian Chen

    2014-01-01

    Full Text Available This paper considers the reliability analysis of a two-component cold standby system with a repairman who may have vacation. The system may fail due to intrinsic factors like aging or deteriorating, or external factors such as Poisson shocks. The arrival time of the shocks follows a Poisson process with the intensity λ>0. Whenever the magnitude of a shock is larger than the prespecified threshold of the operating component, the operating component will fail. The paper assumes that the intrinsic lifetime and the repair time on the component are an extended Poisson process, the magnitude of the shock and the threshold of the operating component are nonnegative random variables, and the vacation time of the repairman obeys the general continuous probability distribution. By using the vector Markov process theory, the supplementary variable method, Laplace transform, and Tauberian theory, the paper derives a number of reliability indices: system availability, system reliability, the rate of occurrence of the system failure, and the mean time to the first failure of the system. Finally, a numerical example is given to validate the derived indices.

  3. Reliability analysis of imperfect coverage systems with a shared warm standby

    Directory of Open Access Journals (Sweden)

    Li Pei-Chang

    2017-01-01

    Full Text Available Redundancy technique is commonly applied to satisfy the reliability requirements of fault-tolerant systems. Warm standby, a compromise between hot standby and cold standby in term of power consumption and recovery time, has attracted wide attention over the past several decades. However, the existing reliability analysis methods for warm standby system with imperfect coverage are difficult to deal with some cases, such as non-exponential time-to-failure distributions for the system components and the systems with shared standbys. In this paper, a new approach based on step function and impulse function is proposed to overcome the limitations of the existing approaches. The reliability of a system including shared standbys is deduced considering two kinds of imperfect fault coverage models, which contain Element Level Coverage (ELC and Fault Level Coverage (FLC. The proposed approach can applicable to any type of time-to-failure distributions for the system components subject to imperfect fault coverage. A case study is presented to illustrate the applications and advantages.

  4. Reliability associated with the Roter Interaction Analysis System (RIAS) adapted for the telemedicine context.

    Science.gov (United States)

    Nelson, Eve-Lynn; Miller, Edward Alan; Larson, Kiley A

    2010-01-01

    This study's purpose was to adapt the Roter Interaction Analysis System (RIAS) for telemedicine clinics and to investigate the adapted measure's reliability. The study also sought to better understand the volume of technology-related utterance in established telemedicine clinics and the feasibility of using the measure within the telemedicine setting. This initial evaluation is a first step before broadly using the adapted measure across technologies and raters. An expert panel adapted the RIAS for the telemedicine context. This involved accounting for all consultation participants (patient, provider, presenter, family) and adding technology-specific subcategories. Ten new and 36 follow-up telemedicine encounters were videotaped and double coded using the adapted RIAS. These consisted primarily of follow-up visits (78.0%) involving patients, providers, presenters, and other parties. Reliability was calculated for those categories with 15 or more utterances. Traditional RIAS categories related to socioemotional and task-focused clusters had fair to excellent levels of reliability in the telemedicine setting. Although there were too few utterances to calculate the reliability of the specific technology-related subcategories, the summary technology-related category proved reliable for patients, providers, and presenters. Overall patterns seen in traditional patient-provider interactions were observed, with the number of provider utterances far exceeding patient, presenter, and family utterances, and few technology-specific utterances. The traditional RIAS is reliable when applied across multiple participants in the telemedicine context. Reliability of technology-related subcategories could not be evaluated; however, the aggregate technology-related cluster was found to be reliable and may be especially relevant in understanding communication patterns with patients new to the telemedicine setting. Use of the RIAS instrument is encouraged to facilitate comparison

  5. MRS [monitored retrievable storage] Systems Study Task 1 report: Waste management system reliability analysis

    International Nuclear Information System (INIS)

    Clark, L.L.; Myers, R.S.

    1989-04-01

    This is one of nine studies undertaken by contractors to the US Department of Energy (DOE), Office of Civilian Radioactive Waste Management (OCRWM), to provide a technical basis for re-evaluating the role of a monitored retrievable storage (MRS) facility. The study evaluates the relative reliabilities of systems with and without an MRS facility using current facility design bases. The principal finding of this report is that the MRS system has several operational advantages that enhance system reliability. These are: (1) the MRS system is likely to encounter fewer technical issues, (2) the MRS would assure adequate system surface storage capacity to accommodate repository construction and startup delays of up to five years or longer if the Nuclear Waste Policy Amendments Act (NWPAA) were amended, (3) the system with an MRS has two federal acceptance facilities with parallel transportation routing and surface storage capacity, and (4) the MRS system would allow continued waste acceptance for up to a year after a major disruption of emplacement operations at the repository

  6. Reliability of a combined biomechanical and surface electromyographical analysis system during dynamic barbell squat exercise.

    Science.gov (United States)

    Brandon, Raphael; Howatson, Glyn; Hunter, Angus

    2011-10-01

    An analysis system for barbell weightlifting exercises is proposed to record reliable performance and neuromuscular responses. The system consists of surface electromyography (sEMG) synchronized with electrogoniometry and a barbell position transducer. The purpose of this study was to establish the reliability of the three components of the system. Nine males (age 28.9 ± 4.8 years, mass 85.7 ± 15.1 kg) performed squat exercise at three loads on three separate trial days. A data acquisition and software system processed maximal knee angle (flexion), mean power for the concentric phase of squat exercise, and normalized root mean square of the vastus lateralis. Inter-trial coefficients of variation for each variable were calculated as 5.3%, 7.8%, and 7.5% respectively. In addition, knee joint motion and barbell displacement were significantly related to each other (bar displacement (m) = 1.39-0.0057 × knee angle (degress), with goodness-of-fit value, r² = 0.817), suggesting knee goniometry alone can represent the kinematics of a multi-joint squat exercise. The proven reliability of the three components of this system allows for real-time monitoring of resistance exercise using the preferred training methods of athletes, which could be valuable in the understanding of the neuromuscular response of elite strength training methods.

  7. A reliability simulation language for reliability analysis

    International Nuclear Information System (INIS)

    Deans, N.D.; Miller, A.J.; Mann, D.P.

    1986-01-01

    The results of work being undertaken to develop a Reliability Description Language (RDL) which will enable reliability analysts to describe complex reliability problems in a simple, clear and unambiguous way are described. Component and system features can be stated in a formal manner and subsequently used, along with control statements to form a structured program. The program can be compiled and executed on a general-purpose computer or special-purpose simulator. (DG)

  8. Development and Reliability Analysis of HTR-PM Reactor Protection System

    International Nuclear Information System (INIS)

    Li Duo; Guo Chao; Xiong Huasheng

    2014-01-01

    High Temperature Gas-Cooled Reactor-Pebble bed Module (HTR-PM) digital Reactor Protection System (RPS) is a dedicated system, which is designed and developed according to HTR-PM NPP protection specifications. To decrease the probability of accident trips and increase the system reliability, HTR-PM RPS has such features as a framework of four redundant channels, two diverse sub-systems in each channel, and two level two-out-of-four logic voters. Reliability analysis of HTR-PM RPS is based on fault tree model. A fault tree is built based on HTR-PM RPS Failure Modes and Effects Analysis (FMEA), and special analysis is focused on the sub-tree of redundant channel ''2-out-of-4'' logic and the fault tree under one channel is bypassed. The qualitative analysis of fault tree, such as RPS weakness according to minimal cut sets, is summarized in the paper. (author)

  9. A Reliability Analysis of a Rainfall Harvesting System in Southern Italy

    Directory of Open Access Journals (Sweden)

    Lorena Liuzzo

    2016-01-01

    Full Text Available Rainwater harvesting (RWH may be an effective alternative water supply solution in regions affected by water scarcity. It has recently become a particularly important option in arid and semi-arid areas (like Mediterranean basins, mostly because of its many benefits and affordable costs. This study provides an analysis of the reliability of using a rainwater harvesting system to supply water for toilet flushing and garden irrigation purposes, with reference to a single-family home in a residential area of Sicily (Southern Italy. A flushing water demand pattern was evaluated using water consumption data collected from a sample of residential customers during an extended measurement campaign. A daily water balance simulation of the rainwater storage tank was performed, and the yield-after-spillage algorithm was used to define the tank release rule. The model’s performance was evaluated using rainfall data from more than 100 different sites located throughout the Sicilian territory. This regional analysis provided annual reliability curves for the system as a function of mean annual precipitation, which have practical applications in this area of study. The uncertainty related to the regional model predictions was also assessed. A cost-benefit analysis highlighted that the implementation of a rainwater harvesting system in Sicily can provide environmental and economic advantages over traditional water supply methods. In particular, the regional analysis identified areas where the application of this system would be most effective.

  10. Preparation of methodology for reliability analysis of selected digital segments of the instrumentation and control systems of NPPs. Pt. 1

    International Nuclear Information System (INIS)

    Hustak, S.; Patrik, M.; Babic, P.

    2000-12-01

    The report is structured as follows: (i) Introduction; (ii) Important notions relating to the safety and dependability of software systems for nuclear power plants (selected notions from IAEA Technical Report No. 397; safety aspects of software application; reliability/dependability aspects of digital systems); (iii) Peculiarities of digital systems and ways to a dependable performance of the required function (failures in the system and principles of defence against them; ensuring resistance of digital systems against failures at various hardware and software levels); (iv) The issue of analytical procedures to assess the safety and reliability of safety-related digital systems (safety and reliability assessment at an early stage of the project; general framework of reliability analysis of complex systems; choice of an appropriate quantitative measure of software reliability); (v) Selected qualitative and quantitative information about the reliability of digital systems; the use of relations between the incidence of various types of faults); and (vi) Conclusions and recommendations. (P.A.)

  11. Reliability analysis of air recirculation and-refrigeration systems of Angra-1 reactor containment

    International Nuclear Information System (INIS)

    Fernandes Filho, T.L.

    1982-10-01

    A reliability analysis of the air refrigeration and recirculation containment systems (ARRCS) of Angra-1 nuclear power plants, were done. The fault tree analysis was used. The failure primary data were taken out of Wash-1400 and IEEE. These data were processed by these following computer codes : Prep-Kitt, Sample, Trebil, Cressex and Streusl for the two stages of ARRCS operation. The design bases accident studied was a LOCA (loss of coolant). The component that more contribution give to the non-availability of ARRCS is the motor of the ARRCS. (E.G.) [pt

  12. A holistic framework of degradation modeling for reliability analysis and maintenance optimization of nuclear safety systems

    International Nuclear Information System (INIS)

    Lin, Yanhui

    2016-01-01

    Components of nuclear safety systems are in general highly reliable, which leads to a difficulty in modeling their degradation and failure behaviors due to the limited amount of data available. Besides, the complexity of such modeling task is increased by the fact that these systems are often subject to multiple competing degradation processes and that these can be dependent under certain circumstances, and influenced by a number of external factors (e.g. temperature, stress, mechanical shocks, etc.). In this complicated problem setting, this PhD work aims to develop a holistic framework of models and computational methods for the reliability-based analysis and maintenance optimization of nuclear safety systems taking into account the available knowledge on the systems, degradation and failure behaviors, their dependencies, the external influencing factors and the associated uncertainties.The original scientific contributions of the work are: (1) For single components, we integrate random shocks into multi-state physics models for component reliability analysis, considering general dependencies between the degradation and two types of random shocks. (2) For multi-component systems (with a limited number of components):(a) a piecewise-deterministic Markov process modeling framework is developed to treat degradation dependency in a system whose degradation processes are modeled by physics-based models and multi-state models; (b) epistemic uncertainty due to incomplete or imprecise knowledge is considered and a finite-volume scheme is extended to assess the (fuzzy) system reliability; (c) the mean absolute deviation importance measures are extended for components with multiple dependent competing degradation processes and subject to maintenance; (d) the optimal maintenance policy considering epistemic uncertainty and degradation dependency is derived by combining finite-volume scheme, differential evolution and non-dominated sorting differential evolution; (e) the

  13. ANALYSIS OF RELIABILITY OF NONRECTORABLE REDUNDANT POWER SYSTEMS TAKING INTO ACCOUNT COMMON FAILURES

    Directory of Open Access Journals (Sweden)

    V. A. Anischenko

    2014-01-01

    Full Text Available Reliability Analysis of nonrestorable redundant power Systems of industrial plants and other consumers of electric energy was carried out. The main attention was paid to numbers failures influence, caused by failures of all elements of System due to one general reason. Noted the main possible reasons of common failures formation. Two main indicators of reliability of non-restorable systems are considered: average time of no-failure operation and mean probability of no-failure operation. Modeling of failures were carried out by mean of division of investigated system into two in-series connected subsystems, one of them indicated independent failures, but the other indicated common failures. Due to joined modeling of single and common failures resulting intensity of failures is the amount incompatible components: intensity statistically independent failures and intensity of common failures of elements and system in total.It is shown the influence of common failures of elements on average time of no-failure operation of system. There is built the scale of preference of systems according to criterion of  average time maximum of no-failure operation, depending on portion of common failures. It is noticed that such common failures don’t influence on the scale of preference, but  change intervals of time, determining the moments of systems failures and excepting them from the number of comparators. There were discussed two problems  of conditionally optimization of  systems’  reservation choice, taking into account their reliability and cost. The first problem is solved due to criterion of minimum cost of system providing mean probability of no-failure operation, the second problem is solved due to criterion of maximum of mean probability of no-failure operation with cost limitation of system.

  14. Systems Analysis Programs for Hands-on Integrated Reliability Evaluations (SAPHIRE) Quality Assurance Manual

    Energy Technology Data Exchange (ETDEWEB)

    C. L. Smith; R. Nims; K. J. Kvarfordt; C. Wharton

    2008-08-01

    The Systems Analysis Programs for Hands-on Integrated Reliability Evaluations (SAPHIRE) is a software application developed for performing a complete probabilistic risk assessment using a personal computer running the Microsoft Windows operating system. SAPHIRE is primarily funded by the U.S. Nuclear Regulatory Commission (NRC). The role of the INL in this project is that of software developer and tester. This development takes place using formal software development procedures and is subject to quality assurance (QA) processes. The purpose of this document is to describe how the SAPHIRE software QA is performed for Version 6 and 7, what constitutes its parts, and limitations of those processes.

  15. Use of eye tracking equipment for human reliability analysis applied to complex system operations

    Energy Technology Data Exchange (ETDEWEB)

    Pinheiro, Andre Ricardo Mendonça; Prado, Eugenio Anselmo Pessoa do; Martins, Marcelo Ramos, E-mail: andrericardopinheiro@usp.br, E-mail: eugenio.prado@labrisco.usp.br, E-mail: mrmatins@usp.br [Universidade de Sao Paulo (LABRISCO/USP), Sao Paulo, SP (Brazil). Lab. de Análise, Avaliação e Gerenciamento de Risco

    2017-07-01

    This article will discuss the preliminary results of an evaluation methodology for the analysis and quantification of manual character errors (human), by monitoring cognitive parameters and skill levels in the operation of a complex control system based on parameters provided by a eye monitoring equipment (Eye Tracker). The research was conducted using a simulator (game) that plays concepts of operation of a nuclear reactor with a split sample for evaluation of aspects of learning, knowledge and standard operating within the context addressed. bridge operators were monitored using the EYE TRACKING, eliminating the presence of the analyst in the evaluation of the operation, allowing the analysis of the results by means of multivariate statistical techniques within the scope of system reliability. The experiments aim to observe state change situations such as stops and scheduled departures, incidents assumptions and common operating characteristics. Preliminary results of this research object indicate that technical and cognitive aspects can contribute to improving the reliability of the available techniques in human reliability, making them more realistic both in the context of quantitative approaches to regulatory and training purposes, as well as reduced incidence of human error. (author)

  16. Use of eye tracking equipment for human reliability analysis applied to complex system operations

    International Nuclear Information System (INIS)

    Pinheiro, Andre Ricardo Mendonça; Prado, Eugenio Anselmo Pessoa do; Martins, Marcelo Ramos

    2017-01-01

    This article will discuss the preliminary results of an evaluation methodology for the analysis and quantification of manual character errors (human), by monitoring cognitive parameters and skill levels in the operation of a complex control system based on parameters provided by a eye monitoring equipment (Eye Tracker). The research was conducted using a simulator (game) that plays concepts of operation of a nuclear reactor with a split sample for evaluation of aspects of learning, knowledge and standard operating within the context addressed. bridge operators were monitored using the EYE TRACKING, eliminating the presence of the analyst in the evaluation of the operation, allowing the analysis of the results by means of multivariate statistical techniques within the scope of system reliability. The experiments aim to observe state change situations such as stops and scheduled departures, incidents assumptions and common operating characteristics. Preliminary results of this research object indicate that technical and cognitive aspects can contribute to improving the reliability of the available techniques in human reliability, making them more realistic both in the context of quantitative approaches to regulatory and training purposes, as well as reduced incidence of human error. (author)

  17. Reliability analysis of multi-trigger binary systems subject to competing failures

    International Nuclear Information System (INIS)

    Wang, Chaonan; Xing, Liudong; Levitin, Gregory

    2013-01-01

    This paper suggests two combinatorial algorithms for the reliability analysis of multi-trigger binary systems subject to competing failure propagation and failure isolation effects. Propagated failure with global effect (PFGE) is referred to as a failure that not only causes outage to the component from which the failure originates, but also propagates through all other system components causing the entire system failure. However, the propagation effect from the PFGE can be isolated in systems with functional dependence (FDEP) behavior. This paper studies two distinct consequences of PFGE resulting from a competition in the time domain between the failure isolation and failure propagation effects. As compared to existing works on competing failures that are limited to systems with a single FDEP group, this paper considers more complicated cases where the systems have multiple dependent FDEP groups. Analysis of such systems is more challenging because both the occurrence order between the trigger failure event and PFGE from the dependent components and the occurrence order among the multiple trigger failure events have to be considered. Two combinatorial and analytical algorithms are proposed. Both of them have no limitation on the type of time-to-failure distributions for the system components. Their correctness is verified using a Markov-based method. An example of memory systems is analyzed to demonstrate and compare the applications and advantages of the two proposed algorithms. - Highlights: ► Reliability of binary systems with multiple dependent functional dependence groups is analyzed. ► Competing failure propagation and failure isolation effect is considered. ► The proposed algorithms are combinatorial and applicable to any arbitrary type of time-to-failure distributions for system components.

  18. Analysis and recommendations for a reliable programming of software based safety systems

    International Nuclear Information System (INIS)

    Nunez McLeod, J.; Nunez McLeod, J.E.; Rivera, S.S.

    1997-01-01

    The present paper summarizes the results of several studies performed for the development of high software on i486 microprocessors, towards its utilization for control and safety systems for nuclear power plants. The work is based on software programmed in C language. Several recommendations oriented to high reliability software are analyzed, relating the requirements on high level language to its influence on assembler level. Several metrics are implemented, that allow for the quantification of the results achieved. New metrics were developed and other were adapted, in order to obtain more efficient indexes for the software description. Such metrics are helpful to visualize the adaptation of the software under development to the quality rules under use. A specific program developed to assist the reliability analyst on this quantification is also present in the paper. It performs the analysis of an executable program written in C language, disassembling it and evaluating its inter al structures. (author)

  19. Analysis of the reliabilities of maglev train power system with FTA method

    Science.gov (United States)

    Long, Zhiqiang; Lu, Zhiquo; Chen, Huixing; Liu, Shaoke

    2003-09-01

    As to the high safeties and reliabilities of the magnetic suspension train, the most fundamental rule is that under all supposed running disturbances, faults, and other urgent conditions, and at any time, the running train can all stop at any given point, where the passengers can get off the train completely and can all find a safe stopping place. The object studied in this paper is the CMS-3 type electromagnetic suspension sample train developed in the National University of Defense Technology. Based on the method of fault tree analysis, the safeties and the reliabilities of the key part (the power system) of the train are analyzed systematically. And the instructive viewpoints and the improving measures are put forward.

  20. Systems Analysis Programs for Hands-on Integrated Reliability Evaluations (SAPHIRE) Tutorial

    Energy Technology Data Exchange (ETDEWEB)

    C. L. Smith; S. T. Beck; S. T. Wood

    2008-08-01

    The Systems Analysis Programs for Hands-on Integrated Reliability Evaluations (SAPHIRE) refers to a set of computer programs that were developed to create and analyze probabilistic risk assessment (PRAs). This volume is the tutorial manual for the SAPHIRE system. In this document, a series of lessons are provided that guide the user through basic steps common to most analyses preformed with SAPHIRE. The tutorial is divided into two major sections covering both basic and advanced features. The section covering basic topics contains lessons that lead the reader through development of a probabilistic hypothetical problem involving a vehicle accident, highlighting the program’s most fundamental features. The advanced features section contains additional lessons that expand on fundamental analysis features of SAPHIRE and provide insights into more complex analysis techniques. Together, these two elements provide an overview into the operation and capabilities of the SAPHIRE software.

  1. Architecture for interlock systems: reliability analysis with regard to safety and availability

    International Nuclear Information System (INIS)

    Wagner, S.; Apollonio, A.; Schmidt, R.; Zerlauth, M.; Vergara-Fernandez, A.

    2012-01-01

    For particle accelerators like LHC and other large experimental physics facilities like ITER, the machine protection relies on complex interlock systems. In the design of interlock loops for the signal exchange in machine protection systems, the choice of the hardware architecture impacts on machine safety and availability. The reliable performance of a machine stop (leaving the machine in a safe state) in case of an emergency, is an inherent requirement. The constraints in terms of machine availability on the other hand may differ from one facility to another. Spurious machine stops, lowering machine availability, may to a certain extent be tolerated in facilities where they do not cause undue equipment wear-out. In order to compare various interlock loop architectures in terms of safety and availability, the occurrence frequencies of related scenarios have been calculated in a reliability analysis, using a generic analytical model. This paper presents the results and illustrates the potential of the analysis method for supporting the choice of interlock system architectures. The results show the advantages of a 2003 (3 redundant lines with 2-out-of-3 voting) over the 6 architectures under consideration for systems with high requirements in both safety and availability

  2. 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

  3. Using wavefront coding technique as an optical encryption system: reliability analysis and vulnerabilities assessment

    Science.gov (United States)

    Konnik, Mikhail V.

    2012-04-01

    Wavefront coding paradigm can be used not only for compensation of aberrations and depth-of-field improvement but also for an optical encryption. An optical convolution of the image with the PSF occurs when a diffractive optical element (DOE) with a known point spread function (PSF) is placed in the optical path. In this case, an optically encoded image is registered instead of the true image. Decoding of the registered image can be performed using standard digital deconvolution methods. In such class of optical-digital systems, the PSF of the DOE is used as an encryption key. Therefore, a reliability and cryptographic resistance of such an encryption method depends on the size and complexity of the PSF used for optical encoding. This paper gives a preliminary analysis on reliability and possible vulnerabilities of such an encryption method. Experimental results on brute-force attack on the optically encrypted images are presented. Reliability estimation of optical coding based on wavefront coding paradigm is evaluated. An analysis of possible vulnerabilities is provided.

  4. Reliability analysis of Diesel Generator power supply system of Prototype Fast Breeder Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, Pramod Kumar, E-mail: pramodks@igcar.gov.in; Bhuvana, V.; Ramakrishnan, M.

    2016-12-15

    Highlights: • The unavailability of DG success is 4.75E−3 for 2/4 and 1.47E−3 for 1/4. • Modeling includes sub systems like CB, SSWS, Fuel oil system & 220 V DC. • DG-FR, DG-FR-CCF and DG maintenance is major contributors of DG unavailability. • Uncertainty analysis has been carried out through Monte Carlo simulations. • Sensitivity analysis identifies DG mechanical FR as most sensitive part. - Abstract: The unavailability of Diesel Generator power supply system has been evaluated using Fault tree method with ISOGRAPH reliability software and is found to be 4.75E−3 for 2/4 (DG success) and 1.47E−3 for 1/4 (DG success). Common cause failures contribute significantly to the unavailability of the system. Statistical analysis indicates that the DG unavailability is uncertain by Error Factor 4.4 (90% confidence bound) for 2 out of 4 DG system (system success) and by Error Factor 4.1 (90% confidence bound) for 1 out of 4 DG system (system success). Support systems namely Safety related service water system, Fuel oil system and circuit breaker control power supply dependency have been modeled. Results of importance analysis and sensitivity study are used to identify significant contributors to unavailability. DG fails to run, DG fails to run due to CCF and DG maintenance out of service is identified as dominant and important contributors of DG unavailability. Uncertainty analysis has been carried out through Monte Carlo simulations.

  5. Failure and Maintenance Analysis Using Web-Based Reliability Database System

    International Nuclear Information System (INIS)

    Hwang, Seok Won; Kim, Myoung Su; Seong, Ki Yeoul; Na, Jang Hwan; Jerng, Dong Wook

    2007-01-01

    Korea Hydro and Nuclear Power Company has lunched the development of a database system for PSA and Maintenance Rule implementation. It focuses on the easy processing of raw data into a credible and useful database for the risk-informed environment of nuclear power plant operation and maintenance. Even though KHNP had recently completed the PSA for all domestic NPPs as a requirement of the severe accident mitigation strategy, the component failure data were only gathered as a means of quantification purposes for the relevant project. So, the data were not efficient enough for the Living PSA or other generic purposes. Another reason to build a real time database is for the newly adopted Maintenance Rule, which requests the utility to continuously monitor the plant risk based on its operation and maintenance performance. Furthermore, as one of the pre-condition for the Risk Informed Regulation and Application, the nuclear regulatory agency of Korea requests the development and management of domestic database system. KHNP is stacking up data of operation and maintenance on the Enterprise Resource Planning (ERP) system since its first opening on July, 2003. But, so far a systematic review has not been performed to apply the component failure and maintenance history for PSA and other reliability analysis. The data stored in PUMAS before the ERP system is introduced also need to be converted and managed into the new database structure and methodology. This reliability database system is a web-based interface on a UNIX server with Oracle relational database. It is designed to be applicable for all domestic NPPs with a common database structure and the web interfaces, therefore additional program development would not be necessary for data acquisition and processing in the near future. Categorization standards for systems and components have been implemented to analyze all domestic NPPs. For example, SysCode (for a system code) and CpCode (for a component code) were newly

  6. A New Method for System Reliability Analysis of Tailings Dam Stability

    Science.gov (United States)

    Liu, X.; Tang, H.; Xiong, C.; Ni, W.

    2012-12-01

    For the purpose of stability evaluation, a tailings dam can be considered as an artificial slope made of special soil materials which mainly come from mine tailings. As a particular engineering project, a tailings dam generally has experienced multi-loop hydraulic sediments as well as a long-term consolidation in the process of construction. The characteristics of sediment and consolidation result in a unique distribution of the soil layers with significant uncertainties, which come from both nature development and various human activities, and thus cause the discrete and the variability of the physical-mechanical properties dramatically greater than the natural geo-materials. Therefore, the location of critical slip surface (CSS) of the dam usually presents a notable drift. So, it means that the reliability evaluation task for a tailings dam is a system reliability problem indeed. Unfortunately, the previous research of reliability of tailings dam was mainly confined to the limit equilibrium method (LEM), which has three obvious drawbacks. First, it just focused on the variability along the slip surface rather than the whole space of the dam. Second, a fixed CSS, instead of variable one, was concerned in most cases. Third, the shape of the CSS was usually simplified to a circular. The present paper tried to construct a new reliability analysis model combined with several advanced techniques involving finite difference method (FDM), Monte Carlo simulation (MCS), support vector machine (SVM) and particle swarm optimization (PSO). The new framework was consisted of four modules. The first one is the limit equilibrium finite difference mode, which employed the FLAC3D code to generate stress fields and then used PSO algorithm to search the location of CSS and corresponding minimum factor of safety (FOS). The most value of this module was that each realization of stress field would lead to a particular CSS and its FOS. In other words, the consideration of the drift of

  7. Reliability Analysis of RSG-GAS Primary Cooling System to Support Aging Management Program

    Science.gov (United States)

    Deswandri; Subekti, M.; Sunaryo, Geni Rina

    2018-02-01

    Multipurpose Research Reactor G.A. Siwabessy (RSG-GAS) which has been operating since 1987 is one of the main facilities on supporting research, development and application of nuclear energy programs in BATAN. Until now, the RSG-GAS research reactor has been successfully operated safely and securely. However, because it has been operating for nearly 30 years, the structures, systems and components (SSCs) from the reactor would have started experiencing an aging phase. The process of aging certainly causes a decrease in reliability and safe performances of the reactor, therefore the aging management program is needed to resolve the issues. One of the programs in the aging management is to evaluate the safety and reliability of the system and also screening the critical components to be managed.One method that can be used for such purposes is the Fault Tree Analysis (FTA). In this papers FTA method is used to screening the critical components in the RSG-GAS Primary Cooling System. The evaluation results showed that the primary isolation valves are the basic events which are dominant against the system failure.

  8. Reliability of steam-turbine rotors. Task 1. Lifetime prediction analysis system. Final report

    International Nuclear Information System (INIS)

    Nair, P.K.; Pennick, H.G.; Peters, J.E.; Wells, C.H.

    1982-12-01

    Task 1 of RP 502, Reliability of Steam Turbine Rotors, resulted in the development of a computerized lifetime prediction analysis system (STRAP) for the automatic evaluation of rotor integrity based upon the results of a boresonic examination of near-bore defects. Concurrently an advanced boresonic examination system (TREES), designed to acquire data automatically for lifetime analysis, was developed and delivered to the maintenance shop of a major utility. This system and a semi-automated, state-of-the-art system (BUCS) were evaluated on two retired rotors as part of the Task 2 effort. A modified nonproprietary version of STRAP, called SAFER, is now available for rotor lifetime prediction analysis. STRAP and SAFER share a common fracture analysis postprocessor for rapid evaluation of either conventional boresonic amplitude data or TREES cell data. The final version of this postprocessor contains general stress intensity correlations for elliptical cracks in a radial stress gradient and provision for elastic-plastic instability of the ligament between an imbedded crack and the bore surface. Both linear elastic and ligament rupture models were developed for rapid analysis of linkup within three-dimensional clusters of defects. Bore stress-rupture criteria are included, but a creep-fatigue crack growth data base is not available. Physical and mechanical properties of air-melt 1CrMoV forgings are built into the program; however, only bounding values of fracture toughness versus temperature are available. Owing to the lack of data regarding the probability of flaw detection for the boresonic systems and of quantitative verification of the flaw linkup analysis, automatic evlauation of boresonic results is not recommended, and the lifetime prediction system is currently restricted to conservative, deterministic analysis of specified flaw geometries

  9. Reliability Analysis of 6-Component Star Markov Repairable System with Spatial Dependence

    Directory of Open Access Journals (Sweden)

    Liying Wang

    2017-01-01

    Full Text Available Star repairable systems with spatial dependence consist of a center component and several peripheral components. The peripheral components are arranged around the center component, and the performance of each component depends on its spatial “neighbors.” Vector-Markov process is adapted to describe the performance of the system. The state space and transition rate matrix corresponding to the 6-component star Markov repairable system with spatial dependence are presented via probability analysis method. Several reliability indices, such as the availability, the probabilities of visiting the safety, the degradation, the alert, and the failed state sets, are obtained by Laplace transform method and a numerical example is provided to illustrate the results.

  10. Reliability analysis and operator modelling

    International Nuclear Information System (INIS)

    Hollnagel, Erik

    1996-01-01

    The paper considers the state of operator modelling in reliability analysis. Operator models are needed in reliability analysis because operators are needed in process control systems. HRA methods must therefore be able to account both for human performance variability and for the dynamics of the interaction. A selected set of first generation HRA approaches is briefly described in terms of the operator model they use, their classification principle, and the actual method they propose. In addition, two examples of second generation methods are also considered. It is concluded that first generation HRA methods generally have very simplistic operator models, either referring to the time-reliability relationship or to elementary information processing concepts. It is argued that second generation HRA methods must recognise that cognition is embedded in a context, and be able to account for that in the way human reliability is analysed and assessed

  11. Analysis Testing of Sociocultural Factors Influence on Human Reliability within Sociotechnical Systems: The Algerian Oil Companies

    Directory of Open Access Journals (Sweden)

    Abdelbaki Laidoune

    2016-09-01

    Conclusion: The explored sociocultural factors influence the human reliability both in qualitative and quantitative manners. The proposed model shows how reliability can be enhanced by some measures such as experience feedback based on, for example, safety improvements, training, and information. With that is added the continuous systems improvements to improve sociocultural reality and to reduce negative behaviors.

  12. Fundamental concepts and relations for reliability analysis of multi-state systems

    International Nuclear Information System (INIS)

    Murchland, J.D.

    1975-01-01

    The fundamental concepts and relations that should be used in the reliability analysis of systems with numerous components are discussed, with an emphasis on calculable quantities. These are: (1) the average probability of being in a state, (2) the average transition rates between states, in the long run or as time functions, and (3) the integrals of the transition rates, which are the expected numbers of transitions. These quantities are related by the net transition relations, and the calculationally vital transition rate relation when the inputs of an item are statistically independent. Assumptions necessary for the existence of these quantities and for the relations are listed, and proofs given. The importance of exploiting the closeness to ''simple'' structure which systems may possess, and the versatility for different problems of a computational technique of ''reduction'' and ''expansion'' are discussed. The key relations for the latter are formally derived. Applications are made to fault trees, structure networks, undirected and directed communication networks

  13. Design and Analysis of a Flexible, Reliable Deep Space Life Support System

    Science.gov (United States)

    Jones, Harry W.

    2012-01-01

    This report describes a flexible, reliable, deep space life support system design approach that uses either storage or recycling or both together. The design goal is to provide the needed life support performance with the required ultra reliability for the minimum Equivalent System Mass (ESM). Recycling life support systems used with multiple redundancy can have sufficient reliability for deep space missions but they usually do not save mass compared to mixed storage and recycling systems. The best deep space life support system design uses water recycling with sufficient water storage to prevent loss of crew if recycling fails. Since the amount of water needed for crew survival is a small part of the total water requirement, the required amount of stored water is significantly less than the total to be consumed. Water recycling with water, oxygen, and carbon dioxide removal material storage can achieve the high reliability of full storage systems with only half the mass of full storage and with less mass than the highly redundant recycling systems needed to achieve acceptable reliability. Improved recycling systems with lower mass and higher reliability could perform better than systems using storage.

  14. Load Control System Reliability

    Energy Technology Data Exchange (ETDEWEB)

    Trudnowski, Daniel [Montana Tech of the Univ. of Montana, Butte, MT (United States)

    2015-04-03

    This report summarizes the results of the Load Control System Reliability project (DOE Award DE-FC26-06NT42750). The original grant was awarded to Montana Tech April 2006. Follow-on DOE awards and expansions to the project scope occurred August 2007, January 2009, April 2011, and April 2013. In addition to the DOE monies, the project also consisted of matching funds from the states of Montana and Wyoming. Project participants included Montana Tech; the University of Wyoming; Montana State University; NorthWestern Energy, Inc., and MSE. Research focused on two areas: real-time power-system load control methodologies; and, power-system measurement-based stability-assessment operation and control tools. The majority of effort was focused on area 2. Results from the research includes: development of fundamental power-system dynamic concepts, control schemes, and signal-processing algorithms; many papers (including two prize papers) in leading journals and conferences and leadership of IEEE activities; one patent; participation in major actual-system testing in the western North American power system; prototype power-system operation and control software installed and tested at three major North American control centers; and, the incubation of a new commercial-grade operation and control software tool. Work under this grant certainly supported the DOE-OE goals in the area of “Real Time Grid Reliability Management.”

  15. Application of fault tree analysis for customer reliability assessment of a distribution power system

    International Nuclear Information System (INIS)

    Abdul Rahman, Fariz; Varuttamaseni, Athi; Kintner-Meyer, Michael; Lee, John C.

    2013-01-01

    A new method is developed for predicting customer reliability of a distribution power system using the fault tree approach with customer weighted values of component failure frequencies and downtimes. Conventional customer reliability prediction of the electric grid employs the system average (SA) component failure frequency and downtime that are weighted by only the quantity of the components in the system. These SA parameters are then used to calculate the reliability and availability of components in the system, and eventually to find the effect on customer reliability. Although this approach is intuitive, information is lost regarding customer disturbance experiences when customer information is not utilized in the SA parameter calculations, contributing to inaccuracies when predicting customer reliability indices in our study. Hence our new approach directly incorporates customer disturbance information in component failure frequency and downtime calculations by weighting these parameters with information of customer interruptions. This customer weighted (CW) approach significantly improves the prediction of customer reliability indices when applied to our reliability model with fault tree and two-state Markov chain formulations. Our method has been successfully applied to an actual distribution power system that serves over 2.1 million customers. Our results show an improved benchmarking performance on the system average interruption frequency index (SAIFI) by 26% between the SA-based and CW-based reliability calculations. - Highlights: ► We model the reliability of a power system with fault tree and two-state Markov chain. ► We propose using customer weighted component failure frequencies and downtimes. ► Results show customer weighted values perform superior to component average values. ► This method successfully incorporates customer disturbance information into the model.

  16. Integration of reliability and tolerance effect analysis

    NARCIS (Netherlands)

    Brombacher, A.C.; de Boer, H.A.; van 't Loo, J.

    1989-01-01

    The authors focus on the development of systems with online optimized reliability. They argue that in the case of online analysis, reliability analysis should have the same importance as functional analysis currently has, and that reliability should be integrated in a design. Further the function of

  17. Systems Analysis Programs for Hands-On Integrated Reliability Evaluations (SAPHIRE) Technical Reference

    Energy Technology Data Exchange (ETDEWEB)

    C. L. Smith; W. J. Galyean; S. T. Beck

    2008-08-01

    The Systems Analysis Programs for Hands-on Integrated Reliability Evaluations (SAPHIRE) is a software application developed for performing a complete probabilistic risk assessment (PRA) using a personal computer (PC) running the Microsoft Windows? operating system. Herein information is provided on the principles used in the construction and operation of Version 6.0 and 7.0 of the SAPHIRE system. This report summarizes the fundamental mathematical concepts of sets and logic, fault trees, and probability. This volume then describes the algorithms used to construct a fault tree and to obtain the minimal cut sets. It gives the formulas used to obtain the probability of the top event from the minimal cut sets, and the formulas for probabilities that apply for various assumptions concerning reparability and mission time. It defines the measures of basic event importance that SAPHIRE can calculate. This volume gives an overview of uncertainty analysis using simple Monte Carlo sampling or Latin Hypercube sampling, and states the algorithms used by this program to generate random basic event probabilities from various distributions. Also covered are enhance capabilities such as seismic analysis, cut set "recovery," end state manipulation, and use of "compound events."

  18. Systems Analysis Programs for Hands-On Integrated Reliability Evaluations (SAPHIRE) Technical Reference Manual

    Energy Technology Data Exchange (ETDEWEB)

    C. L. Smith; W. J. Galyean; S. T. Beck

    2006-07-01

    The Systems Analysis Programs for Hands-on Integrated Reliability Evaluations (SAPHIRE) is a software application developed for performing a complete probabilistic risk assessment (PRA) using a personal computer (PC) running the Microsoft Windows? operating system. Herein information is provided on the principles used in the construction and operation of Version 6.0 and 7.0 of the SAPHIRE system. This report summarizes the fundamental mathematical concepts of sets and logic, fault trees, and probability. This volume then describes the algorithms used to construct a fault tree and to obtain the minimal cut sets. It gives the formulas used to obtain the probability of the top event from the minimal cut sets, and the formulas for probabilities that apply for various assumptions concerning reparability and mission time. It defines the measures of basic event importance that SAPHIRE can calculate. This volume gives an overview of uncertainty analysis using simple Monte Carlo sampling or Latin Hypercube sampling, and states the algorithms used by this program to generate random basic event probabilities from various distributions. Also covered are enhance capabilities such as seismic analysis, cut set "recovery," end state manipulation, and use of "compound events."

  19. Three suggestions on the definition of terms for the safety and reliability analysis of digital systems

    International Nuclear Information System (INIS)

    Kim, Man Cheol; Smidts, Carol S.

    2015-01-01

    As digital instrumentation and control systems are being progressively introduced into nuclear power plants, a growing number of related technical issues are coming to light needing to be resolved. As a result, an understanding of relevant terms and basic concepts becomes increasingly important. Under the framework of the OECD/NEA WGRISK DIGREL Task Group, the authors were involved in reviewing definitions of terms forming the supporting vocabulary for addressing issues related to the safety and reliability analysis of digital instrumentation and control (SRA of DI and C). These definitions were extracted from various standards regulating the disciplines that form the technical and scientific basis of SRA DI and C. The authors discovered that different definitions are provided by different standards within a common discipline and used differently across various disciplines. This paper raises the concern that a common understanding of terms and basic concepts has not yet been established to address the very specific technical issues facing SRA DI and C. Based on the lessons learned from the review of the definitions of interest and the analysis of dependency relationships existing between these definitions, this paper establishes a set of recommendations for the development of a consistent terminology for SRA DI and C. - Highlights: ●We reviewed definitions of terms used in reliability analysis of digital systems. ●Different definitions are provided by different standards within a common discipline. ●Acyclic and cyclic structures of dependency in defining terms are compared. ●Three recommendations for the development of a consistent terminology provided

  20. Integrated Reliability and Risk Analysis System (IRRAS) Version 2.0 user's guide

    International Nuclear Information System (INIS)

    Russell, K.D.; Sattison, M.B.; Rasmuson, D.M.

    1990-06-01

    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. Also provided in the system is an integrated full-screen editor for use when interfacing with remote mainframe computer systems. 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 2.0 and is the subject of this user's guide. Version 2.0 of IRRAS provides all of the same capabilities as Version 1.0 and adds a relational data base facility for managing the data, improved functionality, and improved algorithm performance. 9 refs., 292 figs., 4 tabs

  1. Reliability Analysis of Wind Turbines

    DEFF Research Database (Denmark)

    Toft, Henrik Stensgaard; Sørensen, John Dalsgaard

    2008-01-01

    In order to minimise the total expected life-cycle costs of a wind turbine it is important to estimate the reliability level for all components in the wind turbine. This paper deals with reliability analysis for the tower and blades of onshore wind turbines placed in a wind farm. The limit states...... consideres are in the ultimate limit state (ULS) extreme conditions in the standstill position and extreme conditions during operating. For wind turbines, where the magnitude of the loads is influenced by the control system, the ultimate limit state can occur in both cases. In the fatigue limit state (FLS......) the reliability level for a wind turbine placed in a wind farm is considered, and wake effects from neighbouring wind turbines is taken into account. An illustrative example with calculation of the reliability for mudline bending of the tower is considered. In the example the design is determined according...

  2. Reliability and Maintainability Analysis for the Amine Swingbed Carbon Dioxide Removal System

    Science.gov (United States)

    Dunbar, Tyler

    2016-01-01

    I have performed a reliability & maintainability analysis for the Amine Swingbed payload system. The Amine Swingbed is a carbon dioxide removal technology that has gone through 2,400 hours of International Space Station on-orbit use between 2013 and 2016. While the Amine Swingbed is currently an experimental payload system, the Amine Swingbed may be converted to system hardware. If the Amine Swingbed becomes system hardware, it will supplement the Carbon Dioxide Removal Assembly (CDRA) as the primary CO2 removal technology on the International Space Station. NASA is also considering using the Amine Swingbed as the primary carbon dioxide removal technology for future extravehicular mobility units and for the Orion, which will be used for the Asteroid Redirect and Journey to Mars missions. The qualitative component of the reliability and maintainability analysis is a Failure Modes and Effects Analysis (FMEA). In the FMEA, I have investigated how individual components in the Amine Swingbed may fail, and what the worst case scenario is should a failure occur. The significant failure effects are the loss of ability to remove carbon dioxide, the formation of ammonia due to chemical degradation of the amine, and loss of atmosphere because the Amine Swingbed uses the vacuum of space to regenerate the Amine Swingbed. In the quantitative component of the reliability and maintainability analysis, I have assumed a constant failure rate for both electronic and nonelectronic parts. Using this data, I have created a Poisson distribution to predict the failure rate of the Amine Swingbed as a whole. I have determined a mean time to failure for the Amine Swingbed to be approximately 1,400 hours. The observed mean time to failure for the system is between 600 and 1,200 hours. This range includes initial testing of the Amine Swingbed, as well as software faults that are understood to be non-critical. If many of the commercial parts were switched to military-grade parts, the expected

  3. Advanced Reactor PSA Methodologies for System Reliability Analysis and Source Term Assessment

    Energy Technology Data Exchange (ETDEWEB)

    Grabaskas, D.; Brunett, A.; Passerini, S.; Grelle, A.; Bucknor, M.

    2017-06-26

    Beginning in 2015, a project was initiated to update and modernize the probabilistic safety assessment (PSA) of the GE-Hitachi PRISM sodium fast reactor. This project is a collaboration between GE-Hitachi and Argonne National Laboratory (Argonne), and funded in part by the U.S. Department of Energy. Specifically, the role of Argonne is to assess the reliability of passive safety systems, complete a mechanistic source term calculation, and provide component reliability estimates. The assessment of passive system reliability focused on the performance of the Reactor Vessel Auxiliary Cooling System (RVACS) and the inherent reactivity feedback mechanisms of the metal fuel core. The mechanistic source term assessment attempted to provide a sequence specific source term evaluation to quantify offsite consequences. Lastly, the reliability assessment focused on components specific to the sodium fast reactor, including electromagnetic pumps, intermediate heat exchangers, the steam generator, and sodium valves and piping.

  4. Reliability Block Diagram (RBD) Analysis of NASA Dryden Flight Research Center (DFRC) Flight Termination System and Power Supply

    Science.gov (United States)

    Morehouse, Dennis V.

    2006-01-01

    In order to perform public risk analyses for vehicles containing Flight Termination Systems (FTS), it is necessary for the analyst to know the reliability of each of the components of the FTS. These systems are typically divided into two segments; a transmitter system and associated equipment, typically in a ground station or on a support aircraft, and a receiver system and associated equipment on the target vehicle. This analysis attempts to analyze the reliability of the NASA DFRC flight termination system ground transmitter segment for use in the larger risk analysis and to compare the results against two established Department of Defense availability standards for such equipment.

  5. Accelerated Monte Carlo system reliability analysis through machine-learning-based surrogate models of network connectivity

    International Nuclear Information System (INIS)

    Stern, R.E.; Song, J.; Work, D.B.

    2017-01-01

    The two-terminal reliability problem in system reliability analysis is known to be computationally intractable for large infrastructure graphs. Monte Carlo techniques can estimate the probability of a disconnection between two points in a network by selecting a representative sample of network component failure realizations and determining the source-terminal connectivity of each realization. To reduce the runtime required for the Monte Carlo approximation, this article proposes an approximate framework in which the connectivity check of each sample is estimated using a machine-learning-based classifier. The framework is implemented using both a support vector machine (SVM) and a logistic regression based surrogate model. Numerical experiments are performed on the California gas distribution network using the epicenter and magnitude of the 1989 Loma Prieta earthquake as well as randomly-generated earthquakes. It is shown that the SVM and logistic regression surrogate models are able to predict network connectivity with accuracies of 99% for both methods, and are 1–2 orders of magnitude faster than using a Monte Carlo method with an exact connectivity check. - Highlights: • Surrogate models of network connectivity are developed by machine-learning algorithms. • Developed surrogate models can reduce the runtime required for Monte Carlo simulations. • Support vector machine and logistic regressions are employed to develop surrogate models. • Numerical example of California gas distribution network demonstrate the proposed approach. • The developed models have accuracies 99%, and are 1–2 orders of magnitude faster than MCS.

  6. Cooperative Strategies for Maximum-Flow Problem in Uncertain Decentralized Systems Using Reliability Analysis

    Directory of Open Access Journals (Sweden)

    Hadi Heidari Gharehbolagh

    2016-01-01

    Full Text Available This study investigates a multiowner maximum-flow network problem, which suffers from risky events. Uncertain conditions effect on proper estimation and ignoring them may mislead decision makers by overestimation. A key question is how self-governing owners in the network can cooperate with each other to maintain a reliable flow. Hence, the question is answered by providing a mathematical programming model based on applying the triangular reliability function in the decentralized networks. The proposed method concentrates on multiowner networks which suffer from risky time, cost, and capacity parameters for each network’s arcs. Some cooperative game methods such as τ-value, Shapley, and core center are presented to fairly distribute extra profit of cooperation. A numerical example including sensitivity analysis and the results of comparisons are presented. Indeed, the proposed method provides more reality in decision-making for risky systems, hence leading to significant profits in terms of real cost estimation when compared with unforeseen effects.

  7. Systems analysis programs for hands-on integrated reliability evaluations (SAPHIRE) version 5.0

    International Nuclear Information System (INIS)

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

    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 reference 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]. The SARA database contains PRA data primarily for the dominant accident sequences of a family and descriptive information about the family including event trees, fault trees, and system model diagrams. The number of facility databases that can be accessed is limited only by the amount of disk storage available. To simulate changes to family systems, SARA users change the failure rates of initiating and basic events and/or modify the structure of the cut sets that make up the event trees, fault trees, and systems. The user then evaluates the effects of these changes through the recalculation of the resultant accident sequence probabilities and importance measures. The results are displayed in tables and graphs that may be printed for reports. A preliminary version of the SARA program was completed in August 1985 and has undergone several updates in response to user suggestions and to maintain compatibility with the other SAPHIRE programs. Version 5.0 of SARA provides the same capability as earlier versions and adds the ability to process unlimited cut sets; display fire, flood, and seismic data; and perform more powerful cut set editing

  8. Human error probability evaluation as part of reliability analysis of digital protection system of advanced pressurized water reactor - APR 1400

    International Nuclear Information System (INIS)

    Varde, P. V.; Lee, D. Y.; Han, J. B.

    2003-03-01

    A case of study on human reliability analysis has been performed as part of reliability analysis of digital protection system of the reactor automatically actuates the shutdown system of the reactor when demanded. However, the safety analysis takes credit for operator action as a diverse mean for tripping the reactor for, though a low probability, ATWS scenario. Based on the available information two cases, viz., human error in tripping the reactor and calibration error for instrumentations in protection system, have been analyzed. Wherever applicable a parametric study has also been performed

  9. Reliability Analysis of the Trigger Synchronisation and Distribution System of the LHC Beam Dumping System

    CERN Document Server

    Filippini, R

    2013-01-01

    The Trigger Synchronisation and Distribution System (TSDS) is one of the core components of the LHC Beam Dumping System and an essential element to guarantee that operation with the beam is always safe. The most critical failure of the TSDS is the missed trigger and re-trigger of at least 2 MKD magnets. This report presents the modelling and analysis of the likelihood of the TSDS to develop such a failure scenario during operation. The analysis returns the Safety Integrity Level (SIL) for the TSDS, and the list of the most important contributors. Sensitivity analysis is performed with respect to the failure parameters and with respect to failure dependencies among components that are in the redundant sets. This includes a study of the common cause failures that are in the TSDS architecture. The results in terms of SIL for the TSDS will be compared to the SIL for the previous architecture which was operational until the Long Shutdown 1. Recommendations in order to obtain higher safety by design will also be gi...

  10. Reliability analysis under epistemic uncertainty

    International Nuclear Information System (INIS)

    Nannapaneni, Saideep; Mahadevan, Sankaran

    2016-01-01

    This paper proposes a probabilistic framework to include both aleatory and epistemic uncertainty within model-based reliability estimation of engineering systems for individual limit states. Epistemic uncertainty is considered due to both data and model sources. Sparse point and/or interval data regarding the input random variables leads to uncertainty regarding their distribution types, distribution parameters, and correlations; this statistical uncertainty is included in the reliability analysis through a combination of likelihood-based representation, Bayesian hypothesis testing, and Bayesian model averaging techniques. Model errors, which include numerical solution errors and model form errors, are quantified through Gaussian process models and included in the reliability analysis. The probability integral transform is used to develop an auxiliary variable approach that facilitates a single-level representation of both aleatory and epistemic uncertainty. This strategy results in an efficient single-loop implementation of Monte Carlo simulation (MCS) and FORM/SORM techniques for reliability estimation under both aleatory and epistemic uncertainty. Two engineering examples are used to demonstrate the proposed methodology. - Highlights: • Epistemic uncertainty due to data and model included in reliability analysis. • A novel FORM-based approach proposed to include aleatory and epistemic uncertainty. • A single-loop Monte Carlo approach proposed to include both types of uncertainties. • Two engineering examples used for illustration.

  11. The reliability of the Manchester Triage System (MTS): a meta-analysis.

    Science.gov (United States)

    Mirhaghi, Amir; Mazlom, Reza; Heydari, Abbas; Ebrahimi, Mohsen

    2017-05-01

    Although the Manchester Triage System (MTS) was first developed two decades ago, the reliability of the MTS has not been questioned through comparison with a moderating variable; therefore, the aim of this study is to determine the extent of the reliability of MTS using a meta-analytic review. Electronic databases were searched up to 1 March 2014. Studies were only included if they had reported sample sizes, reliability coefficients, and adequate description of the reliability assessment. The Guidelines for Reporting Reliability and Agreement Studies was used. Two reviewers independently examined abstracts and extracted data. The effect size was obtained by the z-transformation of reliability coefficients. Data were pooled with random-effects models, and meta-regression was performed based on the method-of-moments estimator. Seven studies were included. The pooled coefficient for the MTS was substantial at 0.751 (CI 95%: 0.677 to 0.810); the incidence of mistriage is greater than 50%. Agreement is higher for the latest version of MTS (for adults) among nurse-experts and in countries in closer proximity to the country of MTS origin (the UK, in Manchester) than for the oldest (pediatric) version, nurse-nurse raters, and countries at a greater distance from the UK. The MTS showed an acceptable level of overall reliability in the emergency department, but more development is required to attain almost perfect agreement. © 2016 Chinese Cochrane Center, West China Hospital of Sichuan University and John Wiley & Sons Australia, Ltd.

  12. Reliability and reproducibility analysis of the AOSpine thoracolumbar spine injury classification system by Chinese spinal surgeons.

    Science.gov (United States)

    Cheng, Jie; Liu, Peng; Sun, Dong; Qin, Tingzheng; Ma, Zikun; Liu, Jingpei

    2017-05-01

    The objective of this study was to analyze the interobserver reliability and intraobserver reproducibility of the new AOSpine thoracolumbar spine injury classification system in young Chinese orthopedic surgeons with different levels of experience in spinal trauma. Previous reports suggest that the new AOSpine thoracolumbar spine injury classification system demonstrates acceptable interobserver reliability and intraobserver reproducibility. However, there are few studies in Asia, especially in China. The AOSpine thoracolumbar spine injury classification system was applied to 109 patients with acute, traumatic thoracolumbar spinal injuries by two groups of spinal surgeons with different levels of clinical experience. The Kappa coefficient was used to determine interobserver reliability and intraobserver reproducibility. The overall Kappa coefficient for all cases was 0.362, which represents fair reliability. The Kappa statistic was 0.385 for A-type injuries and 0.292 for B-type injuries, which represents fair reliability, and 0.552 for C-type injuries, which represents moderate reliability. The Kappa coefficient for intraobserver reproducibility was 0.442 for A-type injuries, 0.485 for B-type injuries, and 0.412 for C-type injuries. These values represent moderate reproducibility for all injury types. The raters in Group A provided significantly better interobserver reliability than Group B (P < 0.05). There were no between-group differences in intraobserver reproducibility. This study suggests that the new AO spine injury classification system may be applied in day-to-day clinical practice in China following extensive training of healthcare providers. Further prospective studies in different healthcare providers and clinical settings are essential for validation of this classification system and to assess its utility.

  13. Regulatory analysis for the resolution of Generic Issue 115, enhancement of the reliability of the Westinghouse Solid State Protection System

    International Nuclear Information System (INIS)

    Basdekas, D.L.

    1989-05-01

    Generic Issue 115 addresses a concern related to the reliability of the Westinghouse reactor protection system for plants using the Westinghouse Solid State Protection System (SSPS). Several options for improving the reliability of the Westinghouse reactor trip function for these plants and their effect on core damage frequency (CDF) and overall risk were evaluated. This regulatory analysis includes a quantitative assessment of the costs and benefits associated with the various options for enhancing the reliability of the Westinghouse SSPS and provides insights for consideration and industry initiatives. No new regulatory requirements are proposed. 25 refs., 11 tabs

  14. Reliable and Efficient Procedure for Steady-State Analysis of Nonautonomous and Autonomous Systems

    Directory of Open Access Journals (Sweden)

    J. Dobes

    2012-04-01

    Full Text Available The majority of contemporary design tools do not still contain steady-state algorithms, especially for the autonomous systems. This is mainly caused by insufficient accuracy of the algorithm for numerical integration, but also by unreliable steady-state algorithms themselves. Therefore, in the paper, a very stable and efficient procedure for the numerical integration of nonlinear differential-algebraic systems is defined first. Afterwards, two improved methods are defined for finding the steady state, which use this integration algorithm in their iteration loops. The first is based on the idea of extrapolation, and the second utilizes nonstandard time-domain sensitivity analysis. The two steady-state algorithms are compared by analyses of a rectifier and a C-class amplifier, and the extrapolation algorithm is primarily selected as a more reliable alternative. Finally, the method based on the extrapolation naturally cooperating with the algorithm for solving the differential-algebraic systems is thoroughly tested on various electronic circuits: Van der Pol and Colpitts oscillators, fragment of a large bipolar logical circuit, feedback and distributed microwave oscillators, and power amplifier. The results confirm that the extrapolation method is faster than a classical plain numerical integration, especially for larger circuits with complicated transients.

  15. Reliability analysis of an LCL tuned track segmented bi-directional inductive power transfer system

    DEFF Research Database (Denmark)

    Asif Iqbal, S. M.; Madawala, U. K.; Thrimawithana, D. J.

    2013-01-01

    Bi-directional Inductive Power Transfer (BDIPT) technique is suitable for renewable energy based applications such as electric vehicles (EVs), for the implementation of vehicle-to-grid (V2G) systems. Recently, more efforts have been made by researchers to improve both efficiency and reliability...... for a 1.5 kW BDIPT system in a MATLAB/Simulink environment. Reliability parameters such as failure rate and mean time between failures (MTBF) are compared between the two systems. A nonlinear programming (NP) model is developed for optimizing charging schedule for a stationery EV. A case study of EV...... optimum charging is provided for a 24 hours period indicating minimum cost and higher reliability....

  16. System reliability of corroding pipelines

    International Nuclear Information System (INIS)

    Zhou Wenxing

    2010-01-01

    A methodology is presented in this paper to evaluate the time-dependent system reliability of a pipeline segment that contains multiple active corrosion defects and is subjected to stochastic internal pressure loading. The pipeline segment is modeled as a series system with three distinctive failure modes due to corrosion, namely small leak, large leak and rupture. The internal pressure is characterized as a simple discrete stochastic process that consists of a sequence of independent and identically distributed random variables each acting over a period of one year. The magnitude of a given sequence follows the annual maximum pressure distribution. The methodology is illustrated through a hypothetical example. Furthermore, the impact of the spatial variability of the pressure loading and pipe resistances associated with different defects on the system reliability is investigated. The analysis results suggest that the spatial variability of pipe properties has a negligible impact on the system reliability. On the other hand, the spatial variability of the internal pressure, initial defect sizes and defect growth rates can have a significant impact on the system reliability.

  17. Space Shuttle Propulsion System Reliability

    Science.gov (United States)

    Welzyn, Ken; VanHooser, Katherine; Moore, Dennis; Wood, David

    2011-01-01

    This session includes the following sessions: (1) External Tank (ET) System Reliability and Lessons, (2) Space Shuttle Main Engine (SSME), Reliability Validated by a Million Seconds of Testing, (3) Reusable Solid Rocket Motor (RSRM) Reliability via Process Control, and (4) Solid Rocket Booster (SRB) Reliability via Acceptance and Testing.

  18. Analysis on Sealing Reliability of Bolted Joint Ball Head Component of Satellite Propulsion System

    Science.gov (United States)

    Guo, Tao; Fan, Yougao; Gao, Feng; Gu, Shixin; Wang, Wei

    2018-01-01

    Propulsion system is one of the important subsystems of satellite, and its performance directly affects the service life, attitude control and reliability of the satellite. The Paper analyzes the sealing principle of bolted joint ball head component of satellite propulsion system and discuss from the compatibility of hydrazine anhydrous and bolted joint ball head component, influence of ground environment on the sealing performance of bolted joint ball heads, and material failure caused by environment, showing that the sealing reliability of bolted joint ball head component is good and the influence of above three aspects on sealing of bolted joint ball head component can be ignored.

  19. Risk analysis and reliability

    International Nuclear Information System (INIS)

    Uppuluri, V.R.R.

    1979-01-01

    Mathematical foundations of risk analysis are addressed. The importance of having the same probability space in order to compare different experiments is pointed out. Then the following topics are discussed: consequences as random variables with infinite expectations; the phenomenon of rare events; series-parallel systems and different kinds of randomness that could be imposed on such systems; and the problem of consensus of estimates of expert opinion

  20. Reliability analysis of a two-unit standby system by computer simulation

    Directory of Open Access Journals (Sweden)

    Davidović Tatjana M.

    2003-01-01

    Full Text Available We study the two-unit standby system with repair and with preventive maintenance. Preventive maintenance is introduced in order to make the lifetime of the system longer. Using Monte-Carlo method we simulate the work of the two-unit system and we analyze the influence of different types of preventive maintenance on reliability of the system. Monte-Carlo method enables us to find estimates of various parameters relevant to the system for which there exist no explicit formulas in the literature. .

  1. Reliable Fluid Power Pitch Systems

    DEFF Research Database (Denmark)

    Liniger, Jesper; Pedersen, Henrik Clemmensen; Soltani, Mohsen

    2015-01-01

    The key objectives of wind turbine manufactures and buyers are to reduce the Total Cost of Ownership and Total Cost of Energy. Among others, low downtime of a wind turbine is important to increase the amount of energy produced during its lifetime. Historical data indicate that pitch systems...... accounts for a substantial part of the downtime of wind turbines. With a focus on fluid power pitch systems; this paper presents an overview of methods relevant to assessing and increasing the reliability and availability of such systems. Four major areas are identified and covered; failure analysis...

  2. Systems analysis programs for hands-on integrated reliability evaluations (SAPHIRE), Version 5.0

    International Nuclear Information System (INIS)

    Russell, K.D.; Kvarfordt, K.J.; Hoffman, C.L.

    1995-10-01

    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 Graphical Evaluation Module (GEM) is a special application tool designed for evaluation of operational occurrences using the Accident Sequence Precursor (ASP) program methods. GEM provides the capability for an analyst to quickly and easily perform conditional core damage probability (CCDP) calculations. The analyst can then use the CCDP calculations to determine if the occurrence of an initiating event or a condition adversely impacts safety. It uses models and data developed in the SAPHIRE specially for the ASP program. GEM requires more data than that normally provided in SAPHIRE and will not perform properly with other models or data bases. This is the first release of GEM and the developers of GEM welcome user comments and feedback that will generate ideas for improvements to future versions. GEM is designated as version 5.0 to track GEM codes along with the other SAPHIRE codes as the GEM relies on the same, shared database structure

  3. SAPHIRE6.64, System Analysis Programs for Hands-on Integrated Reliability

    International Nuclear Information System (INIS)

    2001-01-01

    1 - Description of program or function: SAPHIRE is a collection of programs developed for the purpose of performing those functions necessary to create and analyze a complete Probabilistic Risk Assessment (PRA) primarily for nuclear power plants. The programs included in this suite are the Integrated Reliability and Risk Analysis System (IRRAS), the System Analysis and Risk Assessment (SARA) system, the Models And Results Database (MAR-D) system, and the Fault tree, Event tree and P and ID (FEP) editors. Previously these programs were released as separate packages. These programs include functions to allow the user to create event trees and fault trees, to define accident sequences and basic event failure data, to solve system and accident sequence fault trees, to quantify cut sets, and to perform uncertainty analysis on the results. Also included in this program are features to allow the analyst to generate reports and displays that can be used to document the results of an analysis. Since this software is a very detailed technical tool, the user of this program should be familiar with PRA concepts and the methods used to perform these analyses. 2 - Methods: SAPHIRE is written in MODULA-2 and uses an integrated commercial graphics package to interactively construct and edit fault trees. The fault tree solving methods used are industry recognized top down algorithms. For quantification, the program uses standard methods to propagate the failure information through the generated cut sets. SAPHIRE includes a separate module called the Graphical Evaluation Module (GEM). GEM provides a highly specialized user interface with SAPHIRE which automates the process for evaluating operational events at commercial nuclear power plants. Using GEM an analyst can estimate the risk associated with operational events (that is, perform a Level 1, Level 2, and Level 3 analysis for operational events) in a very efficient and expeditious manner. This on-line reference guide will

  4. Reliability of Power Electronic Converter Systems

    DEFF Research Database (Denmark)

    for advancing the reliability, availability, system robustness, and maintainability of PECS at different levels of complexity. Drawing on the experience of an international team of experts, this book explores the reliability of PECS covering topics including an introduction to reliability engineering in power...... electronic converter systems; anomaly detection and remaining-life prediction for power electronics; reliability of DC-link capacitors in power electronic converters; reliability of power electronics packaging; modeling for life-time prediction of power semiconductor modules; minimization of DC......-link capacitance in power electronic converter systems; wind turbine systems; smart control strategies for improved reliability of power electronics system; lifetime modelling; power module lifetime test and state monitoring; tools for performance and reliability analysis of power electronics systems; fault...

  5. Systems Analysis Programs for Hands-on Integrated Reliability Evaluations (SAPHIRE) Code Reference Manual

    International Nuclear Information System (INIS)

    C. L. Smith; K. J. Kvarfordt; S. T. Wood

    2006-01-01

    The Systems Analysis Programs for Hands-on Integrated Reliability Evaluations (SAPHIRE) is a software application developed for performing a complete probabilistic risk assessment (PRA) using a personal computer. SAPHIRE is funded by the U.S. Nuclear Regulatory Commission (NRC) and developed by the Idaho National Laboratory (INL). The INL's primary role in this project is that of software developer. However, the INL also plays an important role in technology transfer by interfacing and supporting SAPHIRE users comprised of a wide range of PRA practitioners from the NRC, national laboratories, the private sector, and foreign countries. SAPHIRE can be used to model a complex system's response to initiating events, quantify associated damage outcome frequencies, and identify important contributors to this damage (Level 1 PRA) and to analyze containment performance during a severe accident and quantify radioactive releases (Level 2 PRA). It can be used for a PRA evaluating a variety of operating conditions, for example, for a nuclear reactor at full power, low power, or at shutdown conditions. Furthermore, SAPHIRE can be used to analyze both internal and external initiating events and has special features for ansforming models built for internal event analysis to models for external event analysis. It can also be used in a limited manner to quantify risk in terms of release consequences to both the public and the environment (Level 3 PRA). SAPHIRE includes a separate module called the Graphical Evaluation Module (GEM). GEM provides a highly specialized user interface with SAPHIRE that automates SAPHIRE process steps for evaluating operational events at commercial nuclear power plants. Using GEM, an analyst can estimate the risk associated with operational events in a very efficient and expeditious manner. This reference guide will introduce the SAPHIRE Version 7.0 software. A brief discussion of the purpose and history of the software is included along with general

  6. Regression analysis of the structure function for reliability evaluation of continuous-state system

    Energy Technology Data Exchange (ETDEWEB)

    Gamiz, M.L., E-mail: mgamiz@ugr.e [Departamento de Estadistica e I.O., Facultad de Ciencias, Universidad de Granada, Granada 18071 (Spain); Martinez Miranda, M.D. [Departamento de Estadistica e I.O., Facultad de Ciencias, Universidad de Granada, Granada 18071 (Spain)

    2010-02-15

    Technical systems are designed to perform an intended task with an admissible range of efficiency. According to this idea, it is permissible that the system runs among different levels of performance, in addition to complete failure and the perfect functioning one. As a consequence, reliability theory has evolved from binary-state systems to the most general case of continuous-state system, in which the state of the system changes over time through some interval on the real number line. In this context, obtaining an expression for the structure function becomes difficult, compared to the discrete case, with difficulty increasing as the number of components of the system increases. In this work, we propose a method to build a structure function for a continuum system by using multivariate nonparametric regression techniques, in which certain analytical restrictions on the variable of interest must be taken into account. Once the structure function is obtained, some reliability indices of the system are estimated. We illustrate our method via several numerical examples.

  7. Development of the design and reliability analysis of a seabed repository system

    International Nuclear Information System (INIS)

    1987-06-01

    This study examines the seabed repository scheme proposed in 1979 for the long term disposal of heat generating radio-active waste and develops it to a standard sufficient to compare its reliability with the drilled emplacement and penetrator schemes. The reinforced concrete repositories contain 324 waste canisters and weigh 982 tonnes fully loaded in water. The repositories are transported up to 6000 km to the disposal area by a special purpose ship and lowered 5.5 km to the seabed on six braided nylon ropes by traction winches. Reliability of the seabed repository system, measured in terms of accidents per year involving loss of one or more canisters, was comparable with the other systems. (author)

  8. Adjoint sensitivity analysis procedure of Markov chains with applications on reliability of IFMIF accelerator-system facilities

    International Nuclear Information System (INIS)

    Balan, I.

    2005-05-01

    This work presents the implementation of the Adjoint Sensitivity Analysis Procedure (ASAP) for the Continuous Time, Discrete Space Markov chains (CTMC), as an alternative to the other computational expensive methods. In order to develop this procedure as an end product in reliability studies, the reliability of the physical systems is analyzed using a coupled Fault-Tree - Markov chain technique, i.e. the abstraction of the physical system is performed using as the high level interface the Fault-Tree and afterwards this one is automatically converted into a Markov chain. The resulting differential equations based on the Markov chain model are solved in order to evaluate the system reliability. Further sensitivity analyses using ASAP applied to CTMC equations are performed to study the influence of uncertainties in input data to the reliability measures and to get the confidence in the final reliability results. The methods to generate the Markov chain and the ASAP for the Markov chain equations have been implemented into the new computer code system QUEFT/MARKOMAGS/MCADJSEN for reliability and sensitivity analysis of physical systems. The validation of this code system has been carried out by using simple problems for which analytical solutions can be obtained. Typical sensitivity results show that the numerical solution using ASAP is robust, stable and accurate. The method and the code system developed during this work can be used further as an efficient and flexible tool to evaluate the sensitivities of reliability measures for any physical system analyzed using the Markov chain. Reliability and sensitivity analyses using these methods have been performed during this work for the IFMIF Accelerator System Facilities. The reliability studies using Markov chain have been concentrated around the availability of the main subsystems of this complex physical system for a typical mission time. The sensitivity studies for two typical responses using ASAP have been

  9. Enhancement of safety analysis reliability for a CANDU-6 reactor using RELAP-CANDU/SCAN coupled code system

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Man Woong; Choi, Yong Seog; Sin, Chul; Kim, Hyun Koon; Kim, Hho Jung [Korea Institute of Nuclear Safety, Taejon (Korea, Republic of); Hwang, Su Hyun; Hong, In Seob; Kim, Chang Hyo [Seoul National University, Seoul (Korea, Republic of)

    2005-07-01

    In LOCA analysis of the CANDU reactor, the system thermal-hydraulic code, RELAP-CANDU, alone cannot predict the transient behavior accurately. Therefore, the best estimate neutronics and system thermal-hydraulic coupled code system is necessary to describe the transient behavior with higher accuracy and reliability. To perform on-line calculation of safety analysis for CANDU reactor, a coupled thermal hydraulics-neutronics code system was developed in such a way that the best-estimate thermal-hydraulic system code for CANDU reactor, RELAP-CANDU, is coupled with the full three-dimensional reactor core kinetic code.

  10. Waste Feed Delivery System Phase 1 Preliminary Reliability and Availability and Maintainability Analysis [SEC 1 and 2

    International Nuclear Information System (INIS)

    CARLSON, A.B.

    1999-01-01

    The document presents updated results of the preliminary reliability, availability, maintainability analysis performed for delivery of waste feed from tanks 241-AZ-101 and 241-AN-105 to British Nuclear Fuels Limited, inc. under the Tank Waste Remediation System Privatization Contract. The operational schedule delay risk is estimated and contributing factors are discussed

  11. Waste Feed Delivery System Phase 1 Preliminary Reliability and Availability and Maintainability Analysis [SEC 1 and 2

    Energy Technology Data Exchange (ETDEWEB)

    CARLSON, A.B.

    1999-11-11

    The document presents updated results of the preliminary reliability, availability, maintainability analysis performed for delivery of waste feed from tanks 241-AZ-101 and 241-AN-105 to British Nuclear Fuels Limited, inc. under the Tank Waste Remediation System Privatization Contract. The operational schedule delay risk is estimated and contributing factors are discussed.

  12. Unavailability Analysis of the Reactor Core Protection System using Reliability Block Diagram

    International Nuclear Information System (INIS)

    Shin, Hyun Kook; Kim, Sung Ho; Choi, Woong Suk; Kim, Jae Hack

    2006-01-01

    The reactor core of nuclear power plants needs to be monitored for the early detection of core abnormal conditions to protect plants from a severe accident. The core protection calculator system (CPCS) has been provided to calculate the departure from nucleate boiling ratio (DNBR) and the local power density (LPD) based on measured parameters of reactor and coolant system. The original CPCS for OPR 1000 has been designed and implemented based on the concurrent 3205 computer system whose components are obsolete. The CPCS based on Westinghouse Common-Q system has recently been implemented for the Shin-Kori Nuclear Power Plant, Units 1 and 2(SKN 1 and 2). An R and D project has been launched to develop new core protection system called as RCOPS (Reactor Core Protection System) with the partnership of KOPEC and Doosan Heavy Industries and Construction Co. RCOPS is implemented on the HFC-6000 safety class programmable logic controller (PLC). In this paper, the reliability of RCOPS is analyzed using the reliability block diagram (RBD) method. The calculated results are compared with that of the CPCS for SKN 1 and 2

  13. Uncertainty analysis methods for estimation of reliability of passive system of VHTR

    International Nuclear Information System (INIS)

    Han, S.J.

    2012-01-01

    An estimation of reliability of passive system for the probabilistic safety assessment (PSA) of a very high temperature reactor (VHTR) is under development in Korea. The essential approach of this estimation is to measure the uncertainty of the system performance under a specific accident condition. The uncertainty propagation approach according to the simulation of phenomenological models (computer codes) is adopted as a typical method to estimate the uncertainty for this purpose. This presentation introduced the uncertainty propagation and discussed the related issues focusing on the propagation object and its surrogates. To achieve a sufficient level of depth of uncertainty results, the applicability of the propagation should be carefully reviewed. For an example study, Latin-hypercube sampling (LHS) method as a direct propagation was tested for a specific accident sequence of VHTR. The reactor cavity cooling system (RCCS) developed by KAERI was considered for this example study. This is an air-cooled type passive system that has no active components for its operation. The accident sequence is a low pressure conduction cooling (LPCC) accident that is considered as a design basis accident for the safety design of VHTR. This sequence is due to a large failure of the pressure boundary of the reactor system such as a guillotine break of coolant pipe lines. The presentation discussed the obtained insights (benefit and weakness) to apply an estimation of reliability of passive system

  14. Systems Analysis Programs for Hands-on Integrated Reliability Evaluations (SAPHIRE) Code Reference Manual

    Energy Technology Data Exchange (ETDEWEB)

    C. L. Smith; K. J. Kvarfordt; S. T. Wood

    2008-08-01

    The Systems Analysis Programs for Hands-on Integrated Reliability Evaluations (SAPHIRE) is a software application developed for performing a complete probabilistic risk assessment (PRA) using a personal computer. SAPHIRE is funded by the U.S. Nuclear Regulatory Commission (NRC) and developed by the Idaho National Laboratory (INL). The INL's primary role in this project is that of software developer. However, the INL also plays an important role in technology transfer by interfacing and supporting SAPHIRE users comprised of a wide range of PRA practitioners from the NRC, national laboratories, the private sector, and foreign countries. SAPHIRE can be used to model a complex system’s response to initiating events, quantify associated damage outcome frequencies, and identify important contributors to this damage (Level 1 PRA) and to analyze containment performance during a severe accident and quantify radioactive releases (Level 2 PRA). It can be used for a PRA evaluating a variety of operating conditions, for example, for a nuclear reactor at full power, low power, or at shutdown conditions. Furthermore, SAPHIRE can be used to analyze both internal and external initiating events and has special features for transforming models built for internal event analysis to models for external event analysis. It can also be used in a limited manner to quantify risk in terms of release consequences to both the public and the environment (Level 3 PRA). SAPHIRE includes a separate module called the Graphical Evaluation Module (GEM). GEM provides a highly specialized user interface with SAPHIRE that automates SAPHIRE process steps for evaluating operational events at commercial nuclear power plants. Using GEM, an analyst can estimate the risk associated with operational events in a very efficient and expeditious manner. This reference guide will introduce the SAPHIRE Version 7.0 software. A brief discussion of the purpose and history of the software is included along with

  15. Systems Analysis Programs for Hands-on Integrated Reliability Evaluations (SAPHIRE) Code Reference Manual

    Energy Technology Data Exchange (ETDEWEB)

    C. L. Smith; K. J. Kvarfordt; S. T. Wood

    2006-07-01

    The Systems Analysis Programs for Hands-on Integrated Reliability Evaluations (SAPHIRE) is a software application developed for performing a complete probabilistic risk assessment (PRA) using a personal computer. SAPHIRE is funded by the U.S. Nuclear Regulatory Commission (NRC) and developed by the Idaho National Laboratory (INL). The INL's primary role in this project is that of software developer. However, the INL also plays an important role in technology transfer by interfacing and supporting SAPHIRE users comprised of a wide range of PRA practitioners from the NRC, national laboratories, the private sector, and foreign countries. SAPHIRE can be used to model a complex system’s response to initiating events, quantify associated damage outcome frequencies, and identify important contributors to this damage (Level 1 PRA) and to analyze containment performance during a severe accident and quantify radioactive releases (Level 2 PRA). It can be used for a PRA evaluating a variety of operating conditions, for example, for a nuclear reactor at full power, low power, or at shutdown conditions. Furthermore, SAPHIRE can be used to analyze both internal and external initiating events and has special features for ansforming models built for internal event analysis to models for external event analysis. It can also be used in a limited manner to quantify risk in terms of release consequences to both the public and the environment (Level 3 PRA). SAPHIRE includes a separate module called the Graphical Evaluation Module (GEM). GEM provides a highly specialized user interface with SAPHIRE that automates SAPHIRE process steps for evaluating operational events at commercial nuclear power plants. Using GEM, an analyst can estimate the risk associated with operational events in a very efficient and expeditious manner. This reference guide will introduce the SAPHIRE Version 7.0 software. A brief discussion of the purpose and history of the software is included along with

  16. Operator reliability assessment system (OPERAS)

    International Nuclear Information System (INIS)

    Spurgin, A.J.; Hallam, J.W.; Spurgin, J.P.; Singh, A.

    1991-01-01

    The paper gives an overview of the OPERAS project. It discusses the background which led to the design of the PC-based data collection and analysis system connected to plant training simulators including those used for nuclear power plants. The usefulness of a system like OPERAS was perceived during an earlier EPRI project, the Operator Reliability Experiments project, by EPRI and PG and E. The data collection and analysis approaches used in OPERAS were developed during the ORE project. The paper not only discusses the design of OPERAS but discusses the functions performed and the current experiences with the two prototype systems. Also listed are potential uses of OPERAS by utility personnel in Operations, Training and PRA groups

  17. Wind turbine reliability analysis

    OpenAIRE

    Pinar Pérez, Jesús María; García Márquez, Fausto Pedro; Tobias, Andrew Mark; Papaelias, Mayorkinos

    2013-01-01

    Against the background of steadily increasing wind power generation worldwide, wind turbine manufacturers are continuing to develop a range of configurations with different combinations of pitch control, rotor speeds, gearboxes, generators and converters. This paper categorizes the main designs, focusing on their reliability by bringing together and comparing data from a selection of major studies in the literature. These are not particularly consistent but plotting failure rates against hour...

  18. Statistical analysis of the reliability of complex systems for maintenance planning

    DEFF Research Database (Denmark)

    Pedersen, Thomas Espelund

    2003-01-01

    is to analyze failure and maintenance data using mathematical and statistical models in order to improve maintenance procedures in the Danish Defence. The first part of the report introduces the maintenance planning problem and presents an overview of models for reliability, failure processes, and maintenance...... planning. This overview is structured to highlight the process of choosing a proper model for a given data set, focusing on different measures of time and the data requirements for the different models. The second part of the report describes the analysis of two data sets from the Danish Defence. The data...

  19. Application of Artificial Intelligence technology to the analysis and synthesis of reliable software systems

    Science.gov (United States)

    Wild, Christian; Eckhardt, Dave

    1987-01-01

    The development of a methodology for the production of highly reliable software is one of the greatest challenges facing the computer industry. Meeting this challenge will undoubtably involve the integration of many technologies. This paper describes the use of Artificial Intelligence technologies in the automated analysis of the formal algebraic specifications of abstract data types. These technologies include symbolic execution of specifications using techniques of automated deduction and machine learning through the use of examples. On-going research into the role of knowledge representation and problem solving in the process of developing software is also discussed.

  20. Test-Retest Reliability of an Automated Infrared-Assisted Trunk Accelerometer-Based Gait Analysis System.

    Science.gov (United States)

    Hsu, Chia-Yu; Tsai, Yuh-Show; Yau, Cheng-Shiang; Shie, Hung-Hai; Wu, Chu-Ming

    2016-07-23

    The aim of this study was to determine the test-retest reliability of an automated infrared-assisted, trunk accelerometer-based gait analysis system for measuring gait parameters of healthy subjects in a hospital. Thirty-five participants (28 of them females; age range, 23-79 years) performed a 5-m walk twice using an accelerometer-based gait analysis system with infrared assist. Measurements of spatiotemporal gait parameters (walking speed, step length, and cadence) and trunk control (gait symmetry, gait regularity, acceleration root mean square (RMS), and acceleration root mean square ratio (RMSR)) were recorded in two separate walking tests conducted 1 week apart. Relative and absolute test-retest reliability was determined by calculating the intra-class correlation coefficient (ICC3,1) and smallest detectable difference (SDD), respectively. The test-retest reliability was excellent for walking speed (ICC = 0.87, 95% confidence interval = 0.74-0.93, SDD = 13.4%), step length (ICC = 0.81, 95% confidence interval = 0.63-0.91, SDD = 12.2%), cadence (ICC = 0.81, 95% confidence interval = 0.63-0.91, SDD = 10.8%), and trunk control (step and stride regularity in anterior-posterior direction, acceleration RMS and acceleration RMSR in medial-lateral direction, and acceleration RMS and stride regularity in vertical direction). An automated infrared-assisted, trunk accelerometer-based gait analysis system is a reliable tool for measuring gait parameters in the hospital environment.

  1. Probabilistic safety assessment of Tehran Research Reactor using systems analysis programs for hands-on integrated reliability evaluations

    International Nuclear Information System (INIS)

    Hosseini, M.H.; Nematollahi, M.R.; Sepanloo, K.

    2004-01-01

    Probabilistic safety assessment application is found to be a practical tool for research reactor safety due to intense involvement of human interactions in an experimental facility. In this document the application of the probabilistic safety assessment to the Tehran Research Reactor is presented. The level 1 practicabilities safety assessment application involved: Familiarization with the plant, selection of accident initiators, mitigating functions and system definitions, event tree constructions and quantifications, fault tree constructions and quantification, human reliability, component failure data base development and dependent failure analysis. Each of the steps of the analysis given above is discussed with highlights from the selected results. Quantification of the constructed models is done using systems analysis programs for hands-on integrated reliability evaluations software

  2. Probabilistic Analysis of Passive Safety System Reliability in Advanced Small Modular Reactors: Methodologies and Lessons Learned

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-06-28

    Many advanced small modular reactor designs rely on passive systems to fulfill safety functions during accident sequences. These systems depend heavily on boundary conditions to induce a motive force, meaning the system can fail to operate as intended due to deviations in boundary conditions, rather than as the result of physical failures. Furthermore, passive systems may operate in intermediate or degraded modes. These factors make passive system operation difficult to characterize with a traditional probabilistic framework that only recognizes discrete operating modes and does not allow for the explicit consideration of time-dependent boundary conditions. Argonne National Laboratory has been examining various methodologies for assessing passive system reliability within a probabilistic risk assessment for a station blackout event at an advanced small modular reactor. This paper describes the most promising options: mechanistic techniques, which share qualities with conventional probabilistic methods, and simulation-based techniques, which explicitly account for time-dependent processes. The primary intention of this paper is to describe the strengths and weaknesses of each methodology and highlight the lessons learned while applying the two techniques while providing high-level results. This includes the global benefits and deficiencies of the methods and practical problems encountered during the implementation of each technique.

  3. Reliability Analysis of Wind Turbines

    DEFF Research Database (Denmark)

    Toft, Henrik Stensgaard; Sørensen, John Dalsgaard

    2008-01-01

    In order to minimise the total expected life-cycle costs of a wind turbine it is important to estimate the reliability level for all components in the wind turbine. This paper deals with reliability analysis for the tower and blades of onshore wind turbines placed in a wind farm. The limit states......) the reliability level for a wind turbine placed in a wind farm is considered, and wake effects from neighbouring wind turbines is taken into account. An illustrative example with calculation of the reliability for mudline bending of the tower is considered. In the example the design is determined according...

  4. Time-Varying, Multi-Scale Adaptive System Reliability Analysis of Lifeline Infrastructure Networks

    Energy Technology Data Exchange (ETDEWEB)

    Gearhart, Jared Lee [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Kurtz, Nolan Scot [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2014-09-01

    The majority of current societal and economic needs world-wide are met by the existing networked, civil infrastructure. Because the cost of managing such infrastructure is high and increases with time, risk-informed decision making is essential for those with management responsibilities for these systems. To address such concerns, a methodology that accounts for new information, deterioration, component models, component importance, group importance, network reliability, hierarchical structure organization, and efficiency concerns has been developed. This methodology analyzes the use of new information through the lens of adaptive Importance Sampling for structural reliability problems. Deterioration, multi-scale bridge models, and time-variant component importance are investigated for a specific network. Furthermore, both bridge and pipeline networks are studied for group and component importance, as well as for hierarchical structures in the context of specific networks. Efficiency is the primary driver throughout this study. With this risk-informed approach, those responsible for management can address deteriorating infrastructure networks in an organized manner.

  5. A practical approach in reliability analysis for mechanical systems: application to irradiated fuel reprocessing plant

    International Nuclear Information System (INIS)

    Sejourne, S.; Humbert, J.M.; Greneche, D.

    1986-10-01

    Design and tests of equipments for the dismantling of fuel assemblies for LWR or FBR in fuel reprocessing plants are studied for reliability. Three examples are given: 1. Qualitative analysis with fault trees and FMEA for a full equipment. This study enabled to propose preventive actions in order to reduce the severity or the probability of a failure. 2. Calculation of the probability of a failure for a part of a mechanical device. This study enabled to show that this part has a very high probability at failure and then, that it is necessary to foresee the possibility of repair. 3. Estimation of the availability of on equipment. Calculations were performed from test results on various prototypes allowing comparisons between them and allowing to verify if expected availability was reached [fr

  6. Analysis of information security reliability: A tutorial

    International Nuclear Information System (INIS)

    Kondakci, Suleyman

    2015-01-01

    This article presents a concise reliability analysis of network security abstracted from stochastic modeling, reliability, and queuing theories. Network security analysis is composed of threats, their impacts, and recovery of the failed systems. A unique framework with a collection of the key reliability models is presented here to guide the determination of the system reliability based on the strength of malicious acts and performance of the recovery processes. A unique model, called Attack-obstacle model, is also proposed here for analyzing systems with immunity growth features. Most computer science curricula do not contain courses in reliability modeling applicable to different areas of computer engineering. Hence, the topic of reliability analysis is often too diffuse to most computer engineers and researchers dealing with network security. This work is thus aimed at shedding some light on this issue, which can be useful in identifying models, their assumptions and practical parameters for estimating the reliability of threatened systems and for assessing the performance of recovery facilities. It can also be useful for the classification of processes and states regarding the reliability of information systems. Systems with stochastic behaviors undergoing queue operations and random state transitions can also benefit from the approaches presented here. - Highlights: • A concise survey and tutorial in model-based reliability analysis applicable to information security. • A framework of key modeling approaches for assessing reliability of networked systems. • The framework facilitates quantitative risk assessment tasks guided by stochastic modeling and queuing theory. • Evaluation of approaches and models for modeling threats, failures, impacts, and recovery analysis of information systems

  7. Reliability analysis of air recirculation and refrigeration systems of Angra-1 reactor contaiment: a reevaluation

    International Nuclear Information System (INIS)

    Oliveira, L.F.S. de; Fleming, P.V.; Frutuoso e Melo, P.F.F.

    1983-01-01

    A realiability analysis of the air refrigeration and recirculation containment systems (ARRCS) of Angra-1 nuclear power plants, were done, aiming to evaluate the probabilities of occurence of a several accident. The systems were analysed for a 24 hours accident, including time failures and demand failures [pt

  8. French power system reliability report 2008

    International Nuclear Information System (INIS)

    Tesseron, J.M.

    2009-06-01

    / consumption), structure of the system and its design rules, other material measures contributing to operation; 5 - Evolution of measures contributing to reliability in the organizational and human domain: reliability culture, management of the human factor, training, iso 9001 certification - management system, feedback (organisation of feedback, evolution of the ESS scale), performance monitoring, crisis organisation, other organizational measures contributing to reliability; 6 - Lessons drawn from the year's events: lessons drawn from the ESS and from their analysis, feedback other than ESS, noteworthy facts concerning other power systems; 7 - reliability-related indicators: CRE chart of key indicators, RTE internal indicators, indicators for external communication on reliability; 8 - Progress actions underway: actions with the partners concerned (TSOS, users, etc.), main lines of research; 9 - RTE regulation and monitoring system: reliability audit programme, reliability audits; 10 - Conclusion and recommendations

  9. 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

  10. Reliability of Power Electronic Converter Systems

    DEFF Research Database (Denmark)

    The main aims of power electronic converter systems (PECS) are to control, convert, and condition electrical power flow from one form to another through the use of solid-state electronics. This book outlines current research into the scientific modeling, experimentation, and remedial measures......-link capacitance in power electronic converter systems; wind turbine systems; smart control strategies for improved reliability of power electronics system; lifetime modelling; power module lifetime test and state monitoring; tools for performance and reliability analysis of power electronics systems; fault...... for advancing the reliability, availability, system robustness, and maintainability of PECS at different levels of complexity. Drawing on the experience of an international team of experts, this book explores the reliability of PECS covering topics including an introduction to reliability engineering in power...

  11. Design for Reliability of Power Electronic Systems

    DEFF Research Database (Denmark)

    Wang, Huai; Ma, Ke; Blaabjerg, Frede

    2012-01-01

    Advances in power electronics enable efficient and flexible processing of electric power in the application of renewable energy sources, electric vehicles, adjustable-speed drives, etc. More and more efforts are devoted to better power electronic systems in terms of reliability to ensure high...... on a 2.3 MW wind power converter is discussed with emphasis on the reliability critical components IGBTs. Different aspects of improving the reliability of the power converter are mapped. Finally, the challenges and opportunities to achieve more reliable power electronic systems are addressed.......). A collection of methodologies based on Physics-of-Failure (PoF) approach and mission profile analysis are presented in this paper to perform reliability-oriented design of power electronic systems. The corresponding design procedures and reliability prediction models are provided. Further on, a case study...

  12. Reliability Based Optimization of Structural Systems

    DEFF Research Database (Denmark)

    Sørensen, John Dalsgaard

    1987-01-01

    The optimization problem to design structural systems such that the reliability is satisfactory during the whole lifetime of the structure is considered in this paper. Some of the quantities modelling the loads and the strength of the structure are modelled as random variables. The reliability...... is estimated using first. order reliability methods ( FORM ). The design problem is formulated as the optimization problem to minimize a given cost function such that the reliability of the single elements satisfies given requirements or such that the systems reliability satisfies a given requirement....... For these optimization problems it is described how a sensitivity analysis can be performed. Next, new optimization procedures to solve the optimization problems are presented. Two of these procedures solve the system reliability based optimization problem sequentially using quasi-analytical derivatives. Finally...

  13. Reliable inverter systems

    Science.gov (United States)

    Nagano, S.

    1979-01-01

    Base driver with common-load-current feedback protects paralleled inverter systems from open or short circuits. Circuit eliminates total system oscillation that can occur in conventional inverters because of open circuit in primary transformer winding. Common feedback signal produced by functioning modules forces operating frequency of failed module to coincide with clock drive so module resumes normal operating frequency in spite of open circuit.

  14. Operation safety of complex industrial systems. Forward-looking analysis and reliability databases; Surete de fonctionnement des systemes industriels complexes. Analyse previsionnelle et bases de donnees de fiabilite

    Energy Technology Data Exchange (ETDEWEB)

    Zwingelstein, G

    2009-06-15

    The forward-looking analysis of systems failure consists in identifying the conditions that may lead to failures and to foresee their consequences on the reliability, maintainability, availability and safety of systems at the design stage or at the operation stage. It is performed from various information, the selection and analysis of which allows to design a system model. The essential information is: a description of the real system (physical and functional structures), the characteristics of the system components and of the interactions between them (failure modes and their consequences), the relations between the system and its environment, and the consideration of human errors at the exploitation step. Content: 1 - steps of an operation safety analysis; 2 - functional analysis methods: FAST, RELIASEP, SADT, IDEFO, APTE and other methods; 3 - Forward-looking analysis methods: qualitative methods, mixed and quantitative methods, human factors; 4 - reliability databases. (J.S.)

  15. 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.)

  16. Guidelines for reliability analysis of digital systems in PSA context. Phase 3. Status report

    Energy Technology Data Exchange (ETDEWEB)

    Authen, S. [Risk Pilot AB, Stockholm (Sweden); Holmberg, J.-E. [VTT Technical Research Centre of Finland, Espoo (Finland)

    2013-03-15

    Digital protection and control systems appear as upgrades in older plants, and are commonplace in new nuclear power plants. To assess the risk of nuclear power plant 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. In 2007, the OECD/NEA CSNI directed the Working Group on Risk Assessment (WGRisk) to set up a task group to coordinate an activity in this field. One of the recommendations was to develop a taxonomy of failure modes of digital components for the purposes of probabilistic safety assessment (PSA), resulting in a follow-up task group called DIGREL. The taxonomy will be the basis of future modelling and quantification efforts. It will also help define a structure for data collection and to review PSA studies. This an interim report of the project. A draft guidelines document on the failure modes taxonomy has been developed. The taxonomy is rather complete covering all levels from the system level down to module and basic component level failure modes, including hardware and software aspects. There are still open issues to be resolved by the task group, especially related to I and C unit and module level taxonomy. In a parallel Nordic activity, a comparison of Nordic experiences and a literature review on main international references has been performed. The study showed a wide range of approaches and solutions to the challenges given by digital I and C, and also indicated that no state-of-the-art currently exists. An existing simplified PSA model has been complemented with fault tree models for a four-redundant distributed protection system in order to study and demonstrate the effect of design features and modelling approaches. The model has been used to test the effect of CCF modelling, fail-safe principle and voting logic. A comparison has been made between unit-level and module-level modelling. (Author)

  17. Guidelines for reliability analysis of digital systems in PSA context. Phase 3. Status report

    International Nuclear Information System (INIS)

    Authen, S.; Holmberg, J.-E.

    2013-03-01

    Digital protection and control systems appear as upgrades in older plants, and are commonplace in new nuclear power plants. To assess the risk of nuclear power plant 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. In 2007, the OECD/NEA CSNI directed the Working Group on Risk Assessment (WGRisk) to set up a task group to coordinate an activity in this field. One of the recommendations was to develop a taxonomy of failure modes of digital components for the purposes of probabilistic safety assessment (PSA), resulting in a follow-up task group called DIGREL. The taxonomy will be the basis of future modelling and quantification efforts. It will also help define a structure for data collection and to review PSA studies. This an interim report of the project. A draft guidelines document on the failure modes taxonomy has been developed. The taxonomy is rather complete covering all levels from the system level down to module and basic component level failure modes, including hardware and software aspects. There are still open issues to be resolved by the task group, especially related to I and C unit and module level taxonomy. In a parallel Nordic activity, a comparison of Nordic experiences and a literature review on main international references has been performed. The study showed a wide range of approaches and solutions to the challenges given by digital I and C, and also indicated that no state-of-the-art currently exists. An existing simplified PSA model has been complemented with fault tree models for a four-redundant distributed protection system in order to study and demonstrate the effect of design features and modelling approaches. The model has been used to test the effect of CCF modelling, fail-safe principle and voting logic. A comparison has been made between unit-level and module-level modelling. (Author)

  18. Innovations in power systems reliability

    CERN Document Server

    Santora, Albert H; Vaccaro, Alfredo

    2011-01-01

    Electrical grids are among the world's most reliable systems, yet they still face a host of issues, from aging infrastructure to questions of resource distribution. Here is a comprehensive and systematic approach to tackling these contemporary challenges.

  19. Systems analysis programs for hands-on integrated reliability evaluations (SAPHIRE) version 5.0, technical reference manual

    International Nuclear Information System (INIS)

    Russell, K.D.; Atwood, C.L.; Galyean, W.J.; Sattison, M.B.; 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. This volume provides information on the principles used in the construction and operation of Version 5.0 of the Integrated Reliability and Risk Analysis System (IRRAS) and the System Analysis and Risk Assessment (SARA) system. It summarizes the fundamental mathematical concepts of sets and logic, fault trees, and probability. This volume then describes the algorithms that these programs use to construct a fault tree and to obtain the minimal cut sets. It gives the formulas used to obtain the probability of the top event from the minimal cut sets, and the formulas for probabilities that are appropriate under various assumptions concerning repairability and mission time. It defines the measures of basic event importance that these programs can calculate. This volume gives an overview of uncertainty analysis using simple Monte Carlo sampling or Latin Hypercube sampling, and states the algorithms used by these programs to generate random basic event probabilities from various distributions. Further references are given, and a detailed example of the reduction and quantification of a simple fault tree is provided in an appendix

  20. Validity and reliability of a portable gait analysis system for measuring spatiotemporal gait characteristics: comparison to an instrumented treadmill.

    Science.gov (United States)

    Donath, Lars; Faude, Oliver; Lichtenstein, Eric; Nüesch, Corina; Mündermann, Annegret

    2016-01-20

    Gait analysis serves as an important tool for clinicians and other health professionals to assess gait patterns related to functional limitations due to neurological or orthopedic conditions. The purpose of this study was to assess the validity of a body-worn inertial sensor system (RehaGait®) for measuring spatiotemporal gait characteristics compared to a stationary treadmill (Zebris) and the reliability of both systems at different walking speeds and slopes. Gait analysis was performed during treadmill walking at different speeds (habitual walking speed (normal speed); 15 % above normal walking speed; 15 % below normal walking speed) and slopes (0 % slope; 15 % slope) in 22 healthy participants twice 1 week apart. Walking speed, stride length, cadence and stride time were computed from the inertial sensor system and the stationary treadmill and compared using repeated measures analysis of variance. Effect sizes of differences between systems were assessed using Cohen's d, and limits of agreement and systematic bias were computed. The RehaGait® system slightly overestimated stride length (+2.7 %) and stride time (+0.8 %) and underestimate cadence (-1.5 %) with small effect sizes for all speeds and slopes (Cohen's d ≤ 0.44) except slow speed at 15 % slope (Cohen's d > 0.80). Walking speed obtained with the RehaGait® system closely matched the speed set on the treadmill tachometer. Intraclass correlation coefficients (ICC) were excellent for speed, cadence and stride time and for stride length at normal and fast speed at 0 % slope (ICC: .91-1.00). Good ICC values were found for stride length at slow speed at 0 % slope and all speeds at 15 % slope (ICC: .73-.90). Both devices had excellent reliability for most gait characteristics (ICC: .91-1.00) except good reliability for the RehaGait® for stride length at normal and fast speed at 0 % slope and at slow speed at 15 % slope (ICC: .80-.87). Larger limits of agreement for walking at 15

  1. An aggregation method of Markov graphs for the reliability analysis of hybrid systems

    Energy Technology Data Exchange (ETDEWEB)

    Schoenig, Raphael [Centre de Recherche en Automatique de Nancy (CRAN), 2, avenue de la Foret de Haye, 54516 Vandoeuvre-les-Nancy (France) and GFI Consulting, 12, rue Rouget de Lisle, 92442 Issy les Moulineaux (France)]. E-mail: raphael.schoenig@mpsa.com; Aubry, Jean-Francois [Centre de Recherche en Automatique de Nancy (CRAN), 2, avenue de la Foret de Haye, 54516 Vandoeuvre-les-Nancy (France)]. E-mail: jean-francois.aubry@isi.u-nancy.fr; Cambois, Thierry [PSA Peugeot Citroen, 18, rue des Fauvelles, 92256 La Garenne Colombes (France)]. E-mail: thierry.cambois@mpsa.com; Hutinet, Tony [GFI Consulting, 12, rue Rouget de Lisle, 92442 Issy les Moulineaux (France)]. E-mail: thutinet@gfi.fr

    2006-02-01

    To meet always increasing safety requirements in car industry, design and safety assessment methods are developed in order to fit the complexity of new embedded mecatronic systems. Hybrid (discrete/continuous) and dynamic features, specific to these systems, require choosing a suitable formalism. These features should also be considered in safety studies made all through the system design. The aim of this paper is to propose a quantitative analysis method based on the construction of an aggregated Markov graph, which allows a limitation of the combinatorial expansion. This graph is directly deducted from the Petri net modelling of the system. It is composed by a set of functional modes and a set of transitions to which statistical information regarding the system dynamics has been added.

  2. Test-Retest Reliability of an Automated Infrared-Assisted Trunk Accelerometer-Based Gait Analysis System

    Directory of Open Access Journals (Sweden)

    Chia-Yu Hsu

    2016-07-01

    Full Text Available The aim of this study was to determine the test-retest reliability of an automated infrared-assisted, trunk accelerometer-based gait analysis system for measuring gait parameters of healthy subjects in a hospital. Thirty-five participants (28 of them females; age range, 23–79 years performed a 5-m walk twice using an accelerometer-based gait analysis system with infrared assist. Measurements of spatiotemporal gait parameters (walking speed, step length, and cadence and trunk control (gait symmetry, gait regularity, acceleration root mean square (RMS, and acceleration root mean square ratio (RMSR were recorded in two separate walking tests conducted 1 week apart. Relative and absolute test-retest reliability was determined by calculating the intra-class correlation coefficient (ICC3,1 and smallest detectable difference (SDD, respectively. The test-retest reliability was excellent for walking speed (ICC = 0.87, 95% confidence interval = 0.74–0.93, SDD = 13.4%, step length (ICC = 0.81, 95% confidence interval = 0.63–0.91, SDD = 12.2%, cadence (ICC = 0.81, 95% confidence interval = 0.63–0.91, SDD = 10.8%, and trunk control (step and stride regularity in anterior-posterior direction, acceleration RMS and acceleration RMSR in medial-lateral direction, and acceleration RMS and stride regularity in vertical direction. An automated infrared-assisted, trunk accelerometer-based gait analysis system is a reliable tool for measuring gait parameters in the hospital environment.

  3. Reliability Growth in Space Life Support Systems

    Science.gov (United States)

    Jones, Harry W.

    2014-01-01

    A hardware system's failure rate often increases over time due to wear and aging, but not always. Some systems instead show reliability growth, a decreasing failure rate with time, due to effective failure analysis and remedial hardware upgrades. Reliability grows when failure causes are removed by improved design. A mathematical reliability growth model allows the reliability growth rate to be computed from the failure data. The space shuttle was extensively maintained, refurbished, and upgraded after each flight and it experienced significant reliability growth during its operational life. In contrast, the International Space Station (ISS) is much more difficult to maintain and upgrade and its failure rate has been constant over time. The ISS Carbon Dioxide Removal Assembly (CDRA) reliability has slightly decreased. Failures on ISS and with the ISS CDRA continue to be a challenge.

  4. Nuclear plant reliability data system. 1979 annual reports of cumulative system and component reliability

    International Nuclear Information System (INIS)

    1979-01-01

    The primary purposes of the information in these reports are the following: to provide operating statistics of safety-related systems within a unit which may be used to compare and evaluate reliability performance and to provide failure mode and failure rate statistics on components which may be used in failure mode effects analysis, fault hazard analysis, probabilistic reliability analysis, and so forth

  5. Analysis of Balancing Requirements in Future Sustainable and Reliable Power Systems

    International Nuclear Information System (INIS)

    Frunt, J.

    2011-01-01

    This thesis elaborates on the rules for power balancing, provides a method for quantifying balancing requirements and examines the effect of future changes on balancing. Chapter 2 elaborates on system balancing and the different actors and entities in the electricity delivery system. The necessity and implementation of power balancing are explained. Also different subsequent markets (i.e., day-ahead markets, intraday markets and imbalance settlement systems) and options to trade electricity are discussed. As the research focusses mainly on the Netherlands, properties of the Dutch imbalance settlement system are analyzed. Based on this framework an in-depth analysis of imbalances and calls for balancing capacity with the corresponding prices is given. This shows the incentives to minimize the amount of imbalance in the system and to participate in the imbalance settlement system. Chapter 3 elaborates on the level of aggregation that the entities, involved in the imbalance settlement system, in electricity markets can have. Based on current market rules, incentives to either grow or shrink and by aggregating more or less entities are discussed. The level of aggregation will directly influence the functioning of the imbalance settlement system. It is shown that larger aggregations benefit more from the canceling out of imbalances. The imbalances of the Netherlands and Belgium have been aggregated to illustrate the possible benefits of aggregating multiple national imbalance settlement systems. The increased penetration of renewable generation strongly influences the planning and operation of the power system. As many renewable energy generators have a fluctuating power output, several methods are discussed in chapter 4 that can be used to classify and quantify the balancing requirements to counteract these fluctuations. Chapter 4 discusses the multiple existing classes of balancing capacity and the corresponding methods to quantify their needs. Due to the

  6. Generation and analysis of large reliability models

    Science.gov (United States)

    Palumbo, Daniel L.; Nicol, David M.

    1990-01-01

    An effort has been underway for several years at NASA's Langley Research Center to extend the capability of Markov modeling techniques for reliability analysis to the designers of highly reliable avionic systems. This effort has been focused in the areas of increased model abstraction and increased computational capability. The reliability model generator (RMG), a software tool which uses as input a graphical, object-oriented block diagram of the system, is discussed. RMG uses an automated failure modes-effects analysis algorithm to produce the reliability model from the graphical description. Also considered is the ASSURE software tool, a parallel processing program which uses the ASSIST modeling language and SURE semi-Markov solution technique. An executable failure modes-effects analysis is used by ASSURE. The successful combination of the power of graphical representation, automated model generation, and parallel computation leads to the conclusion that large system architectures can now be analyzed.

  7. North Wind Power Company 2-kilowatt high-reliability wind system. Phase I. Design and analysis. Technical report

    Energy Technology Data Exchange (ETDEWEB)

    Mayer, D J; Norton, Jr, J H

    1981-07-01

    Results are presented of Phase I of a program to design a 2kW high reliability wind turbine for use in remote locations and harsh environments. In phase I of the program, a predecessor of the proposed design was procured and tested in a wind tunnel and in the freestream to observe operational characteristics. An analytical procedure was developed for designing and modelling the proposed variable axis rotor control system (VARCS). This was then verified by extensive mobile testing of pre-prototype components. A low speed three phase alternator with a Lundel type rotor was designed. Prototypes were fabricated and tested to refine calculation procedures and develop an effective alternator with appropriate characteristics. A solid state field switching regulator was designed and tested successfully. All necessary support elements were designed and engineered. A complete analysis of system reliability was conducted including failure mode and effects analyses and reliability, maintenance and safety analyses. Cost estimates were performed for a mature product in production rates of 1000 per year. Analysis and testing conducted throughout the first phase is included.

  8. Reliability-Based Optimization of Series Systems of Parallel Systems

    DEFF Research Database (Denmark)

    Enevoldsen, I.; Sørensen, John Dalsgaard

    Reliability-based design of structural systems is considered. Especially systems where the reliability model is a series system of parallel systems are analysed. A sensitivity analysis for this class of problems is presented. Direct and sequential optimization procedures to solve the optimization...... problems are described. Numerical tests indicate that a sequential technique called the bounds iteration method (BIM) is particularly fast and stable....

  9. Food and beverage environment analysis and monitoring system: a reliability study in the school food and beverage environment.

    Science.gov (United States)

    Bullock, Sally Lawrence; Craypo, Lisa; Clark, Sarah E; Barry, Jason; Samuels, Sarah E

    2010-07-01

    States and school districts around the country are developing policies that set nutrition standards for competitive foods and beverages sold outside of the US Department of Agriculture's reimbursable school lunch program. However, few tools exist for monitoring the implementation of these new policies. The objective of this research was to develop a computerized assessment tool, the Food and Beverage Environment Analysis and Monitoring System (FoodBEAMS), to collect data on the competitive school food environment and to test the inter-rater reliability of the tool among research and nonresearch professionals. FoodBEAMS was used to collect data in spring 2007 on the competitive foods and beverages sold in 21 California high schools. Adherence of the foods and beverages to California's competitive food and beverage nutrition policies for schools (Senate Bills 12 and 965) was determined using the data collected by both research and nonresearch professionals. The inter-rater reliability between the data collectors was assessed using the intraclass correlation coefficient. Researcher vs researcher and researcher vs nonresearcher inter-rater reliability was high for both foods and beverages, with intraclass correlation coefficients ranging from .972 to .987. Results of this study provide evidence that FoodBEAMS is a promising tool for assessing and monitoring adherence to nutrition standards for competitive foods sold on school campuses and can be used reliably by both research and nonresearch professionals. Copyright 2010 American Dietetic Association. Published by Elsevier Inc. All rights reserved.

  10. Component reliability for electronic systems

    CERN Document Server

    Bajenescu, Titu-Marius I

    2010-01-01

    The main reason for the premature breakdown of today's electronic products (computers, cars, tools, appliances, etc.) is the failure of the components used to build these products. Today professionals are looking for effective ways to minimize the degradation of electronic components to help ensure longer-lasting, more technically sound products and systems. This practical book offers engineers specific guidance on how to design more reliable components and build more reliable electronic systems. Professionals learn how to optimize a virtual component prototype, accurately monitor product reliability during the entire production process, and add the burn-in and selection procedures that are the most appropriate for the intended applications. Moreover, the book helps system designers ensure that all components are correctly applied, margins are adequate, wear-out failure modes are prevented during the expected duration of life, and system interfaces cannot lead to failure.

  11. System Reliability of Timber Structures

    DEFF Research Database (Denmark)

    Kirkegaard, Poul Henning; Sørensen, John Dalsgaard

    2010-01-01

    For reduction of the risk of collapse in the event of loss of structural element(s), a structural engineer may take necessary steps to design a collapse-resistant structure that is insensitive to accidental circumstances e.g. by incorporating characteristics like redundancy, ties, ductility, key ...... elements, alternate load path(s) etc. in the structural design. In general these characteristics can have a positive influence on system reliability of a structure however, in Eurocodes ductility is only awarded for concrete and steel structures but not for timber structures. It is well......-called statical system effect, will usually increase the reliability of the whole structural system and give an extra safety margin compared to the deterministic code results. The aim of this fact sheet is to outline the relationship between system reliability and the characteristics ductility and redundancy....

  12. Reliability analysis in intelligent machines

    Science.gov (United States)

    Mcinroy, John E.; Saridis, George N.

    1990-01-01

    Given an explicit task to be executed, an intelligent machine must be able to find the probability of success, or reliability, of alternative control and sensing strategies. By using concepts for information theory and reliability theory, new techniques for finding the reliability corresponding to alternative subsets of control and sensing strategies are proposed such that a desired set of specifications can be satisfied. The analysis is straightforward, provided that a set of Gaussian random state variables is available. An example problem illustrates the technique, and general reliability results are presented for visual servoing with a computed torque-control algorithm. Moreover, the example illustrates the principle of increasing precision with decreasing intelligence at the execution level of an intelligent machine.

  13. Integrating Reliability Analysis with a Performance Tool

    Science.gov (United States)

    Nicol, David M.; Palumbo, Daniel L.; Ulrey, Michael

    1995-01-01

    A large number of commercial simulation tools support performance oriented studies of complex computer and communication systems. Reliability of these systems, when desired, must be obtained by remodeling the system in a different tool. This has obvious drawbacks: (1) substantial extra effort is required to create the reliability model; (2) through modeling error the reliability model may not reflect precisely the same system as the performance model; (3) as the performance model evolves one must continuously reevaluate the validity of assumptions made in that model. In this paper we describe an approach, and a tool that implements this approach, for integrating a reliability analysis engine into a production quality simulation based performance modeling tool, and for modeling within such an integrated tool. The integrated tool allows one to use the same modeling formalisms to conduct both performance and reliability studies. We describe how the reliability analysis engine is integrated into the performance tool, describe the extensions made to the performance tool to support the reliability analysis, and consider the tool's performance.

  14. Comparing the treatment of uncertainty in Bayesian networks and fuzzy expert systems used for a human reliability analysis application

    International Nuclear Information System (INIS)

    Baraldi, Piero; Podofillini, Luca; Mkrtchyan, Lusine; Zio, Enrico; Dang, Vinh N.

    2015-01-01

    The use of expert systems can be helpful to improve the transparency and repeatability of assessments in areas of risk analysis with limited data available. In this field, human reliability analysis (HRA) is no exception, and, in particular, dependence analysis is an HRA task strongly based on analyst judgement. The analysis of dependence among Human Failure Events refers to the assessment of the effect of an earlier human failure on the probability of the subsequent ones. This paper analyses and compares two expert systems, based on Bayesian Belief Networks and Fuzzy Logic (a Fuzzy Expert System, FES), respectively. The comparison shows that a BBN approach should be preferred in all the cases characterized by quantifiable uncertainty in the input (i.e. when probability distributions can be assigned to describe the input parameters uncertainty), since it provides a satisfactory representation of the uncertainty and its output is directly interpretable for use within PSA. On the other hand, in cases characterized by very limited knowledge, an analyst may feel constrained by the probabilistic framework, which requires assigning probability distributions for describing uncertainty. In these cases, the FES seems to lead to a more transparent representation of the input and output uncertainty. - Highlights: • We analyse treatment of uncertainty in two expert systems. • We compare a Bayesian Belief Network (BBN) and a Fuzzy Expert System (FES). • We focus on the input assessment, inference engines and output assessment. • We focus on an application problem of interest for human reliability analysis. • We emphasize the application rather than math to reach non-BBN or FES specialists

  15. Toward formal analysis of ultra-reliable computers: A total systems approach

    International Nuclear Information System (INIS)

    Chisholm, G.H.; Kljaich, J.; Smith, B.T.; Wojcik, A.S.

    1986-01-01

    This paper describes the application of modeling and analysis techniques to software that is designed to execute on four channel version of the the Charles Stark Draper Laboratory (CSDL) Fault-Tolerant Processor, referred to as the Draper FTP. The software performs sensor validation of four independent measures (singlas) from the primary pumps of the Experimental Breeder Reactor-II operated by Argonne National Laboratory-West, and from the validated signals formulates a flow trip signal for the reactor safety system. 11 refs., 4 figs

  16. Bayesian Reliability Analysis of Non-Stationarity in Multi-agent Systems

    Directory of Open Access Journals (Sweden)

    TONT Gabriela

    2013-05-01

    Full Text Available The Bayesian methods provide information about the meaningful parameters in a statistical analysis obtained by combining the prior and sampling distributions to form the posterior distribution of theparameters. The desired inferences are obtained from this joint posterior. An estimation strategy for hierarchical models, where the resulting joint distribution of the associated model parameters cannotbe evaluated analytically, is to use sampling algorithms, known as Markov Chain Monte Carlo (MCMC methods, from which approximate solutions can be obtained. Both serial and parallel configurations of subcomponents are permitted. The capability of time-dependent method to describe a multi-state system is based on a case study, assessingthe operatial situation of studied system. The rationality and validity of the presented model are demonstrated via a case of study. The effect of randomness of the structural parameters is alsoexamined.

  17. Proposal of a concept and reliability analysis for a fusion plant magnet protection system

    International Nuclear Information System (INIS)

    Schnauder, H.; Pamfilie, E.

    1993-05-01

    The unavailability for the current switch down in case of a demand in the magnet coils of a fusion demonstration plant must be decreased by a few orders of magnitude as compared to the one of experimental facilities. The safety requirements to prevent initiation of event sequences which might lead to the release of radioactivity and energy by the plant must be fulfilled with the same standards as applied in a normally applicable plant. On the basis of this proven technology a general usable magnet protection system will be proposed, which achieves some considerable improvements in the failure detectability as compared to the conventional protection systems. It will be demonstrated by fault tree analysis that the principal demands on safety can be satisfied by that approach. The improvements are achieved by the use of an additional microprocessor supported system for failure detection without being used for initiation of any safety related actions. An influence on a safety action by the additional system therefore is excluded. (orig.) [de

  18. Use of F.M.E.A. for reliability analysis of safety systems in nuclear power plants

    International Nuclear Information System (INIS)

    Barbet, J.F.; Llory, M.; Villemeur, A.

    1982-01-01

    In the framework of the French nuclear power plant program, reliability studies of safety systems have been carried out at the Electricite de France since 1975. The main results of the studies are examined; about the methodological aspects it appears useful to develop an inductive approach such as the Failure Modes and Effects Analysis (F.M.E.A.). The method is described with its advantages and limitations; the possibilities of use of F.M.E.A. to solve specific safety problems are investigated. To conclude, the future trends of research and development in this field at Electricite de France are pointed out [fr

  19. Reliability analysis of idealized tunnel support system using probability-based methods with case studies

    NARCIS (Netherlands)

    Gharouni-Nik, M.; Naeimi, M.; Ahadi, S.; Alimoradi, Z.

    2014-01-01

    In order to determine the overall safety of a tunnel support lining, a reliability-based approach is presented in this paper. Support elements in jointed rock tunnels are provided to control the ground movement caused by stress redistribution during the tunnel drive. Main support elements contribute

  20. Review and critical analysis: Rolling-element bearings for system life and reliability

    Science.gov (United States)

    Irwin, A. S.; Anderson, W. J.; Derner, W. J.

    1985-01-01

    A ball and cylindrical roller bearing technical specification which incorporates the latest state-of-the-art advancements was prepared for the purpose of improving bearing reliability in U.S. Army aircraft. The current U.S. Army aviation bearing designs and applications, including life analyses, were analyzed. A bearing restoration and refurbishment specification was prepared to improve bearing availability.

  1. Reliability Analysis of Main-axis Control System of the Equatorial Antarctica Astronomical Telescope Based on Fault Tree

    Science.gov (United States)

    LI, Y.; Yang, S. H.

    2017-05-01

    The Antarctica astronomical telescopes work chronically on the top of the unattended South Pole, and they have only one chance to maintain every year. Due to the complexity of the optical, mechanical, and electrical systems, the telescopes are hard to be maintained and need multi-tasker expedition teams, which means an excessive awareness is essential for the reliability of the Antarctica telescopes. Based on the fault mechanism and fault mode of the main-axis control system for the equatorial Antarctica astronomical telescope AST3-3 (Antarctic Schmidt Telescopes 3-3), the method of fault tree analysis is introduced in this article, and we obtains the importance degree of the top event from the importance degree of the bottom event structure. From the above results, the hidden problems and weak links can be effectively found out, which will indicate the direction for promoting the stability of the system and optimizing the design of the system.

  2. Reliability analysis techniques for the design engineer

    International Nuclear Information System (INIS)

    Corran, E.R.; Witt, H.H.

    1982-01-01

    This paper describes a fault tree analysis package that eliminates most of the housekeeping tasks involved in proceeding from the initial construction of a fault tree to the final stage of presenting a reliability analysis in a safety report. It is suitable for designers with relatively little training in reliability analysis and computer operation. Users can rapidly investigate the reliability implications of various options at the design stage and evolve a system which meets specified reliability objectives. Later independent review is thus unlikely to reveal major shortcomings necessitating modification and project delays. The package operates interactively, allowing the user to concentrate on the creative task of developing the system fault tree, which may be modified and displayed graphically. For preliminary analysis, system data can be derived automatically from a generic data bank. As the analysis proceeds, improved estimates of critical failure rates and test and maintenance schedules can be inserted. The technique is applied to the reliability analysis of the recently upgraded HIFAR Containment Isolation System. (author)

  3. An approach for reliability analysis of industrial systems using PSO and IFS technique.

    Science.gov (United States)

    Garg, Harish; Rani, Monica

    2013-11-01

    The main objective of this paper is to present a technique for computing the membership functions of the intuitionistic fuzzy set (IFS) by utilizing imprecise, uncertain and vague data. In literature so far, membership functions of IFS are computed via using fuzzy arithmetic operations within collected data and hence contain a wide range of uncertainties. Thus it is necessary for optimizing these spread by formulating a nonlinear optimization problem through ordinary arithmetic operations instead of fuzzy operations. Particle swarm optimization (PSO) has been used for constructing their membership functions. Sensitivity as well as performance analysis has also been conducted for finding the critical component of the system. Finally the computed results are compared with existing results. The suggested framework has been illustrated with the help of a case. © 2013 Published by ISA. All rights reserved.

  4. Reliability-Based Optimization of Series Systems of Parallel Systems

    DEFF Research Database (Denmark)

    Enevoldsen, I.; Sørensen, John Dalsgaard

    1993-01-01

    Reliability-based design of structural systems is considered. In particular, systems where the reliability model is a series system of parallel systems are treated. A sensitivity analysis for this class of problems is presented. Optimization problems with series systems of parallel systems......) a sequential formulation based on optimality criteria; and (4) a sequential formulation including a new so-called bounds iteration method (BIM). Numerical tests indicate that the sequential technique including the BIM is particularly fast and stable. The B1M is not only effective in reliabilitybased...... optimization of series systems of parallel systems, but it is also efficient in reliability-based optimization of series systems in general....

  5. A system-of-systems framework for the reliability analysis of distributed generation systems accounting for the impact of degraded communication networks

    International Nuclear Information System (INIS)

    Mo, Hua-Dong; Li, Yan-Fu; Zio, Enrico

    2016-01-01

    Highlights: • A system-of-systems framework is proposed for reliability analysis of DG system. • The impact of degraded communication networks is included and quantified. • Various uncertainties and contingencies in the DG system are considered. • A Monte Carlo simulation-optimal power flow computational framework is developed. • The results of the application study show the power of the proposed framework. - Abstract: Distributed generation (DG) systems install communication networks for managing real-time energy imbalance. Different from previous research, which typically assumes perfect communication networks, this work aims to quantitatively account for the impact of degraded communication networks on DG systems performance. The degraded behavior of communication networks is modeled by stochastic continuous time transmission delays and packet dropouts. On the DG systems side, we consider the inherent uncertainties of renewable energy sources, loads and energy prices. We develop a Monte Carlo simulation-optimal power flow (MCS-OPF) computational framework that is capable of generating consecutive time-dependent operating scenarios of the integrated system. Quantitative analysis is carried out to measure the impact of communication networks degradation onto the DG systems. For illustration, the framework is applied to a modified IEEE 13 nodes test feeder. The results demonstrate that the degraded communication networks can significantly deteriorate the performance of the integrated system. A grey differential model-based prediction method for reconstructing missing data is effective in mitigating the influence of the degraded communication networks.

  6. Dependent systems reliability estimation by structural reliability approach

    DEFF Research Database (Denmark)

    Kostandyan, Erik; Sørensen, John Dalsgaard

    2014-01-01

    Estimation of system reliability by classical system reliability methods generally assumes that the components are statistically independent, thus limiting its applicability in many practical situations. A method is proposed for estimation of the system reliability with dependent components, where...... the leading failure mechanism(s) is described by physics of failure model(s). The proposed method is based on structural reliability techniques and accounts for both statistical and failure effect correlations. It is assumed that failure of any component is due to increasing damage (fatigue phenomena...... identification. Application of the proposed method can be found in many real world systems....

  7. Architectural design and reliability analysis of a fail-operational brake-by-wire system from ISO 26262 perspectives

    International Nuclear Information System (INIS)

    Sinha, Purnendu

    2011-01-01

    Next generation drive-by-wire automotive systems enabling autonomous driving will build on the fail-operational capabilities of electronics, control and software (ECS) architectural solutions. Developing such architectural designs that would meet dependability requirements and satisfy other system constraints is a challenging task and will possibly lead to a paradigm shift in automotive ECS architecture design and development activities. This aspect is becoming quite relevant while designing battery-driven electric vehicles with integrated in-wheel drive-train and chassis subsystems. In such highly integrated dependable systems, many of the primary features and functions are attributed to the highest safety critical ratings. Brake-by-wire is one such system that interfaces with active safety features built into an automobile, and which in turn is expected to provide fail-operational capabilities. In this paper, building up on the basic concepts of fail-silent and fail-operational systems design we propose a system-architecture for a brake-by-wire system with fail-operational capabilities. The design choices are supported with proper rationale and design trade-offs. Safety and reliability analysis of the proposed system architecture is performed as per the ISO 26262 standard for functional safety of electrical/electronic systems in road vehicles.

  8. Designing magnetic systems for reliability

    International Nuclear Information System (INIS)

    Heitzenroeder, P.J.

    1991-01-01

    Designing magnetic system is an iterative process in which the requirements are set, a design is developed, materials and manufacturing processes are defined, interrelationships with the various elements of the system are established, engineering analyses are performed, and fault modes and effects are studied. Reliability requires that all elements of the design process, from the seemingly most straightforward such as utilities connection design and implementation, to the most sophisticated such as advanced finite element analyses, receives a balanced and appropriate level of attention. D.B. Montgomery's study of magnet failures has shown that the predominance of magnet failures tend not to be in the most intensively engineered areas, but are associated with insulation, leads, ad unanticipated conditions. TFTR, JET, JT-60, and PBX are all major tokamaks which have suffered loss of reliability due to water leaks. Similarly the majority of causes of loss of magnet reliability at PPPL has not been in the sophisticated areas of the design but are due to difficulties associated with coolant connections, bus connections, and external structural connections. Looking towards the future, the major next-devices such as BPX and ITER are most costly and complex than any of their predecessors and are pressing the bounds of operating levels, materials, and fabrication. Emphasis on reliability is a must as the fusion program enters a phase where there are fewer, but very costly devices with the goal of reaching a reactor prototype stage in the next two or three decades. This paper reviews some of the magnet reliability issues which PPPL has faced over the years the lessons learned from them, and magnet design and fabrication practices which have been found to contribute to magnet reliability

  9. Nuclear power plant safe operation principles and some topics concerning systems reliability analysis

    International Nuclear Information System (INIS)

    Borsky, M.; Kreim, R.; Stanicek, J.

    1997-01-01

    General safety criteria are specified, and nuclear power plant equipment is classified into systems either important or unimportant for nuclear safety. The former class is subdivided into safety systems and safety related systems. The safety requirements concern earthquakes, storms, fires, floods, man-induced events, and equipment failures. The actual state of systems important for safety is described. (M.D.)

  10. RELY: A reliability modeling system for analysis of sodium-sulfur battery configurations

    Energy Technology Data Exchange (ETDEWEB)

    Hostick, C.J.; Huber, H.D.; Doggett, W.H.; Dirks, J.A.; Dovey, J.F.; Grinde, R.B.; Littlefield, J.S.; Cuta, F.M.

    1987-06-01

    In support of the Office of Energy Storage and Distribution of the US Department of Energy (DOE), Pacific Northwest Laboratory has produced a microcomputer-based software package, called RELY, to assess the impact of sodium-sulfur cell reliability on constant current discharge battery performance. The Fortran-based software operates on IBM microcomputers and IBM-compatibles that have a minimum of 512K of internal memory. The software package has three models that provide the following: (1) a description of the failure distribution parameters used to model cell failure, (2) a Monte Carlo simulation of battery life, and (3) a detailed discharge model for a user-specified battery discharge cycle. 6 refs., 31 figs., 4 tabs.

  11. Human reliability guidance - How to increase the synergies between human reliability, human factors, and system design and engineering. Phase 2: The American Point of View - Insights of how the US nuclear industry works with human reliability analysis

    International Nuclear Information System (INIS)

    Oxstrand, J.

    2010-12-01

    The main goal of this Nordic Nuclear Safety Research Council (NKS) project is to produce guidance for how to use human reliability analysis (HRA) to strengthen overall safety. The project consists of two substudies: The Nordic Point of View - A User Needs Analysis, and The American Point of View - Insights of How the US Nuclear Industry Works with HRA. The purpose of the Nordic Point of View study was a user needs analysis that aimed to survey current HRA practices in the Nordic nuclear industry, with the main focus being to connect HRA to system design. In this study, 26 Nordic (Swedish and Finnish) nuclear power plant specialists with research, practitioner, and regulatory expertise in HRA, PRA, HSI, and human performance were interviewed. This study was completed in 2009. This study concludes that HRA is an important tool when dealing with human factors in control room design or modernizations. The Nordic Point of View study showed areas where the use of HRA in the Nordic nuclear industry could be improved. To gain more knowledge about how these improvements could be made, and what improvements to focus on, the second study was conducted. The second study is focused on the American nuclear industry, which has many more years of experience with risk assessment and human reliability than the Nordic nuclear industry. Interviews were conducted to collect information to help the author understand the similarities and differences between the American and the Nordic nuclear industries, and to find data regarding the findings from the first study. The main focus of this report is to identify potential HRA improvements based on the data collected in the American Point of View survey. (Author)

  12. Human reliability guidance - How to increase the synergies between human reliability, human factors, and system design and engineering. Phase 2: The American Point of View - Insights of how the US nuclear industry works with human reliability analysis

    Energy Technology Data Exchange (ETDEWEB)

    Oxstrand, J. (Vattenfall Ringhals AB, Stockholm (Sweden))

    2010-12-15

    The main goal of this Nordic Nuclear Safety Research Council (NKS) project is to produce guidance for how to use human reliability analysis (HRA) to strengthen overall safety. The project consists of two substudies: The Nordic Point of View - A User Needs Analysis, and The American Point of View - Insights of How the US Nuclear Industry Works with HRA. The purpose of the Nordic Point of View study was a user needs analysis that aimed to survey current HRA practices in the Nordic nuclear industry, with the main focus being to connect HRA to system design. In this study, 26 Nordic (Swedish and Finnish) nuclear power plant specialists with research, practitioner, and regulatory expertise in HRA, PRA, HSI, and human performance were interviewed. This study was completed in 2009. This study concludes that HRA is an important tool when dealing with human factors in control room design or modernizations. The Nordic Point of View study showed areas where the use of HRA in the Nordic nuclear industry could be improved. To gain more knowledge about how these improvements could be made, and what improvements to focus on, the second study was conducted. The second study is focused on the American nuclear industry, which has many more years of experience with risk assessment and human reliability than the Nordic nuclear industry. Interviews were conducted to collect information to help the author understand the similarities and differences between the American and the Nordic nuclear industries, and to find data regarding the findings from the first study. The main focus of this report is to identify potential HRA improvements based on the data collected in the American Point of View survey. (Author)

  13. Dynamic Reliability Analysis of Gear Transmission System of Wind Turbine in Consideration of Randomness of Loadings and Parameters

    Directory of Open Access Journals (Sweden)

    Lei Wang

    2014-01-01

    Full Text Available A dynamic model of gear transmission system of wind turbine is built with consideration of randomness of loads and parameters. The dynamic response of the system is obtained using the theory of random sampling and the Runge-Kutta method. According to rain flow counting principle, the dynamic meshing forces are converted into a series of luffing fatigue load spectra. The amplitude and frequency of the equivalent stress are obtained using equivalent method of Geber quadratic curve. Moreover, the dynamic reliability model of components and system is built according to the theory of probability of cumulative fatigue damage. The system reliability with the random variation of parameters is calculated and the influence of random parameters on dynamic reliability of components is analyzed. In the end, the results of the proposed method are compared with that of Monte Carlo method. This paper can be instrumental in the design of wind turbine gear transmission system with more advantageous dynamic reliability.

  14. A reavaluation of the reliability analysis of the low pressure injection system for Angra-1

    International Nuclear Information System (INIS)

    Oliveira, L.F.S. de; Fleming, P.V.; Frutuoso e Melo, P.F.F.; Tayt-Sohn, L.C.

    1983-01-01

    The emergency core cooling system of Angra 1 is analysed aiming at the low pressure injection systems, using the fault tree technique. All the failure mode of the components are considered for this analyse. (author) [pt

  15. PWR system reliability improvement activities

    International Nuclear Information System (INIS)

    Yoshikawa, Yuichiro

    1985-01-01

    In Japan lacking in energy resources, it is our basic energy policy to accelerate the development program of nuclear power, thereby reducing our dependence. As referred to in the foregoing, every effort has been exerted on our part to improve the PWR system reliability by dint of the so-called 'HOMEMADE' TQC activities, which is our brain-child as a result of applying to the energy industry the quality control philosophy developed in the field of manufacturing industry

  16. Reliability analysis of repairable multi-state system with common bus performance sharing

    International Nuclear Information System (INIS)

    Yu, Huan; Yang, Jun; Mo, Huadong

    2014-01-01

    In this paper, an instantaneous availability model for repairable multi-state system (MSS) with common bus performance sharing is proposed. The repairable MSS consists of some multi-state units and a common bus performance redistribution system. Each unit in the system has several performance levels and must satisfy its individual random demand. A unit can transmit the surplus performance to other units in real time through the common bus performance redistribution system, if it has a performance that exceeds its demand. The entire system fails if the demand of any unit is not satisfied. A new method based on the combination of the stochastic process method and the universal generating function technique is suggested to evaluate the instantaneous availability and the mean instantaneous performance deficiency of the proposed repairable MSS. Two examples are given for applications in the end

  17. Reliability evaluation of a natural circulation system

    International Nuclear Information System (INIS)

    Jafari, Jalil; D'Auria, Francesco; Kazeminejad, Hossein; Davilu, Hadi

    2003-01-01

    This paper discusses a reliability study performed with reference to a passive thermohydraulic natural circulation (NC) system, named TTL-1. A methodology based on probabilistic techniques has been applied with the main purpose to optimize the system design. The obtained results have been adopted to estimate the thermal-hydraulic reliability (TH-R) of the same system. A total of 29 relevant parameters (including nominal values and plausible ranges of variations) affecting the design and the NC performance of the TTL-1 loop are identified and a probability of occurrence is assigned for each value based on expert judgment. Following procedures established for the uncertainty evaluation of thermal-hydraulic system codes results, 137 system configurations have been selected and each configuration has been analyzed via the Relap5 best-estimate code. The reference system configuration and the failure criteria derived from the 'mission' of the passive system are adopted for the evaluation of the system TH-R. Four different definitions of a less-than-unity 'reliability-values' (where unity represents the maximum achievable reliability) are proposed for the performance of the selected passive system. This is normally considered fully reliable, i.e. reliability-value equal one, in typical Probabilistic Safety Assessment (PSA) applications in nuclear reactor safety. The two 'point' TH-R values for the considered NC system were found equal to 0.70 and 0.85, i.e. values comparable with the reliability of a pump installed in an 'equivalent' forced circulation (active) system having the same 'mission'. The design optimization study was completed by a regression analysis addressing the output of the 137 calculations: heat losses, undetected leakage, loop length, riser diameter, and equivalent diameter of the test section have been found as the most important parameters bringing to the optimal system design and affecting the TH-R. As added values for this work, the comparison has

  18. Culture Representation in Human Reliability Analysis

    Energy Technology Data Exchange (ETDEWEB)

    David Gertman; Julie Marble; Steven Novack

    2006-12-01

    Understanding human-system response is critical to being able to plan and predict mission success in the modern battlespace. Commonly, human reliability analysis has been used to predict failures of human performance in complex, critical systems. However, most human reliability methods fail to take culture into account. This paper takes an easily understood state of the art human reliability analysis method and extends that method to account for the influence of culture, including acceptance of new technology, upon performance. The cultural parameters used to modify the human reliability analysis were determined from two standard industry approaches to cultural assessment: Hofstede’s (1991) cultural factors and Davis’ (1989) technology acceptance model (TAM). The result is called the Culture Adjustment Method (CAM). An example is presented that (1) reviews human reliability assessment with and without cultural attributes for a Supervisory Control and Data Acquisition (SCADA) system attack, (2) demonstrates how country specific information can be used to increase the realism of HRA modeling, and (3) discusses the differences in human error probability estimates arising from cultural differences.

  19. Systems Analysis Programs for Hands-on Integrated Reliability Evaluations (SAPHIRE) Version 5.0: Data loading manual. Volume 10

    International Nuclear Information System (INIS)

    VanHorn, R.L.; Wolfram, L.M.; Fowler, R.D.; Beck, S.T.; Smith, C.L.

    1995-04-01

    The Systems Analysis Programs for Hands-on Integrated Reliability Evaluations (SAPHIRE) suite of programs can be used to organize and standardize in an electronic format information from probabilistic risk assessments or individual plant examinations. The Models and Results Database (MAR-D) program of the SAPHIRE suite serves as the repository for probabilistic risk assessment and individual plant examination data and information. This report demonstrates by examples the common electronic and manual methods used to load these types of data. It is not a stand alone document but references documents that contribute information relative to the data loading process. This document provides a more detailed discussion and instructions for using SAPHIRE 5.0 only when enough information on a specific topic is not provided by another available source

  20. Computation of posterior distribution in Bayesian analysis – application in an intermittently used reliability system

    Directory of Open Access Journals (Sweden)

    V. S.S. Yadavalli

    2002-09-01

    Full Text Available Bayesian estimation is presented for the stationary rate of disappointments, D∞, for two models (with different specifications of intermittently used systems. The random variables in the system are considered to be independently exponentially distributed. Jeffreys’ prior is assumed for the unknown parameters in the system. Inference about D∞ is being restrained in both models by the complex and non-linear definition of D∞. Monte Carlo simulation is used to derive the posterior distribution of D∞ and subsequently the highest posterior density (HPD intervals. A numerical example where Bayes estimates and the HPD intervals are determined illustrates these results. This illustration is extended to determine the frequentistical properties of this Bayes procedure, by calculating covering proportions for each of these HPD intervals, assuming fixed values for the parameters.

  1. Application of simple approximate system analysis methods for reliability and availability improvement of reactor WWER-1000

    International Nuclear Information System (INIS)

    Manchev, B.; Marinova, B.; Nenkova, B.

    2001-01-01

    The method described on this report provides a set of simple, easily understood 'approximate' models applicable to a large class of system architectures. Constructing a Markov model of each redundant subsystem and its replacement after that by a pseudo-component develops the approximation models. Of equal importance, the models can be easily understood even of non-experts, including managers, high-level decision-makers and unsophisticated consumers. A necessary requirement for their application is the systems to be repairable and the mean time to repair to be much smaller than the mean time to failure. This ia a case most often met in the real practice. Results of the 'approximate' model application on a technological system of Kozloduy NPP are also presented. The results obtained can be compared quite favorably with the results obtained by using SAPHIRE software

  2. Reliability Analysis of Tubular Joints in Offshore Structures

    DEFF Research Database (Denmark)

    Thoft-Christensen, Palle; Sørensen, John Dalsgaard

    1987-01-01

    Reliability analysis of single tubular joints and offshore platforms with tubular joints is" presented. The failure modes considered are yielding, punching, buckling and fatigue failure. Element reliability as well as systems reliability approaches are used and illustrated by several examples....... Finally, optimal design of tubular.joints with reliability constraints is discussed and illustrated by an example....

  3. Methodology for time-dependent reliability analysis of accident sequences and complex reactor systems

    International Nuclear Information System (INIS)

    Paula, H.M.

    1984-01-01

    The work presented here is of direct use in probabilistic risk assessment (PRA) and is of value to utilities as well as the Nuclear Regulatory Commission (NRC). Specifically, this report presents a methodology and a computer program to calculate the expected number of occurrences for each accident sequence in an event tree. The methodology evaluates the time-dependent (instantaneous) and the average behavior of the accident sequence. The methodology accounts for standby safety system and component failures that occur (a) before they are demanded, (b) upon demand, and (c) during the mission (system operation). With respect to failures that occur during the mission, this methodology is unique in the sense that it models components that can be repaired during the mission. The expected number of system failures during the mission provides an upper bound for the probability of a system failure to run - the mission unreliability. The basic event modeling includes components that are continuously monitored, periodically tested, and those that are not tested or are otherwise nonrepairable. The computer program ASA allows practical applications of the method developed. This work represents a required extension of the presently available methodology and allows a more realistic PRA of nuclear power plants

  4. Reliability Analysis of Elasto-Plastic Structures

    DEFF Research Database (Denmark)

    Thoft-Christensen, Palle; Sørensen, John Dalsgaard

    1984-01-01

    . Failure of this type of system is defined either as formation of a mechanism or by failure of a prescribed number of elements. In the first case failure is independent of the order in which the elements fail, but this is not so by the second definition. The reliability analysis consists of two parts...... are described and the two definitions of failure can be used by the first formulation, but only the failure definition based on formation of a mechanism by the second formulation. The second part of the reliability analysis is an estimate of the failure probability for the structure on the basis...

  5. Reliability analysis of the containment spray system of Angra-1 : the injection phase

    International Nuclear Information System (INIS)

    Gibelli, S.M.O.; Oliveira, L.F.S. de.

    1981-12-01

    The system studied is projected to perform two basic functions : to reduce the pressure and temperature in the containment after a LOCA (loss of coolant accident), to break the main steam line or the main feed line in the containment after a LOCA (loss of coolant accident), to break the main steam line or the main feed line in the containment and to remove the fission products, mainly the iodine of the containment atmosphere. The spray system was analyzed concerning the probability of non-acomplishment of both functions at the same time; therefore the failure of the components of the chemical aditions subsystem are included in the failure tree shown here. (E.G.) [pt

  6. Guidelines for reliability analysis of digital systems in PSA context - Phase 2 Status report

    International Nuclear Information System (INIS)

    Authen, S.; Gustafsson, J.; Holmberg, J.-E.

    2012-02-01

    The OECD/NEA CSNI Working Group on Risk Assessment (WGRisk) has set up a task group called DIGREL to develop a taxonomy of failure modes of digital components for the purposes of probabilistic safety assessment (PSA). A parallel Nordic activity carried out a pre-study where a comparison of Nordic experiences and a literature review were performed. The study showed a wide range of approaches and solutions to the challenges given by digital I and C. In 2011, a proposal for the failure modes taxonomy was defined. This is based on a set of requirements agreed on the purpose of the taxonomy. The following levels of details can be distinguished from the hardware point of view: (1) the entire system, (2) a division, (3) processing units (and cabinets), (4) modules, i.e. subcomponents of processing units and (5) generic components, i.e. subcomponents of modules. Module level seems to be the most appropriate from the PSA modelling point of view. The software failure modes taxonomy is still an open issue. An existing simplified PSA model has been complemented with fault tree models for a four-redundant distributed protection system in order to study and demonstrate the effect of design features and modelling approaches. The example shows that even rather simple I and C design leads to rather complex model despite of the fact that many things have been simplified and only a few protection signals are considered. One lesson from the example is that the Alpha factor model should be used to model common cause failures instead of the Beta factor model. Two options were developed to the comparison of different fail-safe principles. The role of detectable and undetectable failure modes with respect to the failed versus spurious actuations can be clearly seen in the results, showing the importance to model these features in PSA. (Author)

  7. Guidelines for reliability analysis of digital systems in PSA context - Phase 2 Status report

    Energy Technology Data Exchange (ETDEWEB)

    Authen, S. (Risk Pilot AB, Stockholm (Sweden)); Gustafsson, J. (Royal Institute of Technology (Sweden)); Holmberg, J.-E. (VTT Technical Research Centre of Finland (Finland))

    2012-02-15

    The OECD/NEA CSNI Working Group on Risk Assessment (WGRisk) has set up a task group called DIGREL to develop a taxonomy of failure modes of digital components for the purposes of probabilistic safety assessment (PSA). A parallel Nordic activity carried out a pre-study where a comparison of Nordic experiences and a literature review were performed. The study showed a wide range of approaches and solutions to the challenges given by digital I and C. In 2011, a proposal for the failure modes taxonomy was defined. This is based on a set of requirements agreed on the purpose of the taxonomy. The following levels of details can be distinguished from the hardware point of view: (1) the entire system, (2) a division, (3) processing units (and cabinets), (4) modules, i.e. subcomponents of processing units and (5) generic components, i.e. subcomponents of modules. Module level seems to be the most appropriate from the PSA modelling point of view. The software failure modes taxonomy is still an open issue. An existing simplified PSA model has been complemented with fault tree models for a four-redundant distributed protection system in order to study and demonstrate the effect of design features and modelling approaches. The example shows that even rather simple I and C design leads to rather complex model despite of the fact that many things have been simplified and only a few protection signals are considered. One lesson from the example is that the Alpha factor model should be used to model common cause failures instead of the Beta factor model. Two options were developed to the comparison of different fail-safe principles. The role of detectable and undetectable failure modes with respect to the failed versus spurious actuations can be clearly seen in the results, showing the importance to model these features in PSA. (Author)

  8. Structural Reliability Analysis of Wind Turbines: A Review

    Directory of Open Access Journals (Sweden)

    Zhiyu Jiang

    2017-12-01

    Full Text Available The paper presents a detailed review of the state-of-the-art research activities on structural reliability analysis of wind turbines between the 1990s and 2017. We describe the reliability methods including the first- and second-order reliability methods and the simulation reliability methods and show the procedure for and application areas of structural reliability analysis of wind turbines. Further, we critically review the various structural reliability studies on rotor blades, bottom-fixed support structures, floating systems and mechanical and electrical components. Finally, future applications of structural reliability methods to wind turbine designs are discussed.

  9. Reliability Analysis of the LHC Beam Dumping System Taking into Account the Operational Experience during LHC Run 1

    CERN Document Server

    Filippini, R; Magnin, N; Uythoven, J A

    2014-01-01

    The LHC beam dumping system operated reliably during the Run 1 period of the LHC (2009 2013). A number of internal failures of the beam dumping system occurred that, because of built-in safety features, resulted in a safe removal of the particle beams from the machine, so called “internal beam

  10. Reliability of Power Electronic Converter Systems

    DEFF Research Database (Denmark)

    for advancing the reliability, availability, system robustness, and maintainability of PECS at different levels of complexity. Drawing on the experience of an international team of experts, this book explores the reliability of PECS covering topics including an introduction to reliability engineering in power......-tolerant adjustable speed drive systems; mission profile oriented reliability design in wind turbine and photovoltaic systems; reliability of power conversion systems in photovoltaic applications; power supplies for computers; and high-power converters. Reliability of Power Electronic Converter Systems is essential...... reading for researchers, professionals and students working with power electronics and their applications, particularly those specializing in the development and application of power electronic converters and systems....

  11. CADRIGS--computer aided design reliability interactive graphics system

    International Nuclear Information System (INIS)

    Kwik, R.J.; Polizzi, L.M.; Sticco, S.; Gerrard, P.B.; Yeater, M.L.; Hockenbury, R.W.; Phillips, M.A.

    1982-01-01

    An integrated reliability analysis program combining graphic representation of fault trees, automated data base loadings and reference, and automated construction of reliability code input files was developed. The functional specifications for CADRIGS, the computer aided design reliability interactive graphics system, are presented. Previously developed fault tree segments used in auxiliary feedwater system safety analysis were constructed on CADRIGS and, when combined, yielded results identical to those resulting from manual input to the same reliability codes

  12. Software Architecture Reliability Analysis using Failure Scenarios

    NARCIS (Netherlands)

    Tekinerdogan, B.; Sözer, Hasan; Aksit, Mehmet

    2005-01-01

    We propose a Software Architecture Reliability Analysis (SARA) approach that benefits from both reliability engineering and scenario-based software architecture analysis to provide an early reliability analysis of the software architecture. SARA makes use of failure scenarios that are prioritized

  13. Reliability and Cost Analysis of a Rainwater Harvesting System in Peri-Urban Regions of Greater Sydney, Australia

    Directory of Open Access Journals (Sweden)

    Evan Hajani

    2014-04-01

    Full Text Available In large cities, rainwater tanks are used to save mains water, but in peri-urban and rural areas, rainwater tanks are used as a sole water supply for many households, as these regions often do not have any other means of water supply. This paper investigates the performance of a rainwater harvesting system (RWHS in peri-urban regions of Greater Sydney, Australia. Considering the daily rainfall data over the entire period of record at ten different locations, it has been found that a 5 kL tank can meet 96% to 99% of the demand for toilet and laundry use depending on the location in Greater Sydney regions. However, in the driest year, a 5 kL tank can meet 69% to 99% of toilet and laundry demand depending on the location. Based on the results of life cycle cost analysis, it has been found that a 5 kL tank has the highest benefit–cost ratio (ranging from 0.86 to 0.97 among the eight possible tank sizes examined in this study. Interestingly, for a 5 kL tank, with a combined use (i.e., toilet, laundry and irrigation, the current water price in Sydney needs to be increased by 3% to 16% to achieve a benefit–cost ratio exceeding one. A set of regression equations are developed which can be used to estimate reliability using the average annual rainfall data at any arbitrary location in the peri-urban regions of Greater Sydney. The method presented in this paper can also be applied to other Australian states and other countries to estimate water savings and reliability of a RWHS using daily rainfall data.

  14. Reliability and validity of CODA motion analysis system for measuring cervical range of motion in patients with cervical spondylosis and anterior cervical fusion

    Science.gov (United States)

    Gao, Zhongyang; Song, Hui; Ren, Fenggang; Li, Yuhuan; Wang, Dong; He, Xijing

    2017-01-01

    The aim of the present study was to evaluate the reliability of the Cartesian Optoelectronic Dynamic Anthropometer (CODA) motion system in measuring the cervical range of motion (ROM) and verify the construct validity of the CODA motion system. A total of 26 patients with cervical spondylosis and 22 patients with anterior cervical fusion were enrolled and the CODA motion analysis system was used to measure the three-dimensional cervical ROM. Intra- and inter-rater reliability was assessed by interclass correlation coefficients (ICCs), standard error of measurement (SEm), Limits of Agreements (LOA) and minimal detectable change (MDC). Independent samples t-tests were performed to examine the differences of cervical ROM between cervical spondylosis and anterior cervical fusion patients. The results revealed that in the cervical spondylosis group, the reliability was almost perfect (intra-rater reliability: ICC, 0.87–0.95; LOA, −12.86–13.70; SEm, 2.97–4.58; inter-rater reliability: ICC, 0.84–0.95; LOA, −13.09–13.48; SEm, 3.13–4.32). In the anterior cervical fusion group, the reliability was high (intra-rater reliability: ICC, 0.88–0.97; LOA, −10.65–11.08; SEm, 2.10–3.77; inter-rater reliability: ICC, 0.86–0.96; LOA, −10.91–13.66; SEm, 2.20–4.45). The cervical ROM in the cervical spondylosis group was significantly higher than that in the anterior cervical fusion group in all directions except for left rotation. In conclusion, the CODA motion analysis system is highly reliable in measuring cervical ROM and the construct validity was verified, as the system was sufficiently sensitive to distinguish between the cervical spondylosis and anterior cervical fusion groups based on their ROM. PMID:29285065

  15. Reliability and validity of CODA motion analysis system for measuring cervical range of motion in patients with cervical spondylosis and anterior cervical fusion.

    Science.gov (United States)

    Gao, Zhongyang; Song, Hui; Ren, Fenggang; Li, Yuhuan; Wang, Dong; He, Xijing

    2017-12-01

    The aim of the present study was to evaluate the reliability of the Cartesian Optoelectronic Dynamic Anthropometer (CODA) motion system in measuring the cervical range of motion (ROM) and verify the construct validity of the CODA motion system. A total of 26 patients with cervical spondylosis and 22 patients with anterior cervical fusion were enrolled and the CODA motion analysis system was used to measure the three-dimensional cervical ROM. Intra- and inter-rater reliability was assessed by interclass correlation coefficients (ICCs), standard error of measurement (SEm), Limits of Agreements (LOA) and minimal detectable change (MDC). Independent samples t-tests were performed to examine the differences of cervical ROM between cervical spondylosis and anterior cervical fusion patients. The results revealed that in the cervical spondylosis group, the reliability was almost perfect (intra-rater reliability: ICC, 0.87-0.95; LOA, -12.86-13.70; SEm, 2.97-4.58; inter-rater reliability: ICC, 0.84-0.95; LOA, -13.09-13.48; SEm, 3.13-4.32). In the anterior cervical fusion group, the reliability was high (intra-rater reliability: ICC, 0.88-0.97; LOA, -10.65-11.08; SEm, 2.10-3.77; inter-rater reliability: ICC, 0.86-0.96; LOA, -10.91-13.66; SEm, 2.20-4.45). The cervical ROM in the cervical spondylosis group was significantly higher than that in the anterior cervical fusion group in all directions except for left rotation. In conclusion, the CODA motion analysis system is highly reliable in measuring cervical ROM and the construct validity was verified, as the system was sufficiently sensitive to distinguish between the cervical spondylosis and anterior cervical fusion groups based on their ROM.

  16. Human Reliability Analysis: session summary

    International Nuclear Information System (INIS)

    Hall, R.E.

    1985-01-01

    The use of Human Reliability Analysis (HRA) to identify and resolve human factors issues has significantly increased over the past two years. Today, utilities, research institutions, consulting firms, and the regulatory agency have found a common application of HRA tools and Probabilistic Risk Assessment (PRA). The ''1985 IEEE Third Conference on Human Factors and Power Plants'' devoted three sessions to the discussion of these applications and a review of the insights so gained. This paper summarizes the three sessions and presents those common conclusions that were discussed during the meeting. The paper concludes that session participants supported the use of an adequately documented ''living PRA'' to address human factors issues in design and procedural changes, regulatory compliance, and training and that the techniques can produce cost effective qualitative results that are complementary to more classical human factors methods

  17. Qualitative analysis in reliability and safety studies

    International Nuclear Information System (INIS)

    Worrell, R.B.; Burdick, G.R.

    1976-01-01

    The qualitative evaluation of system logic models is described as it pertains to assessing the reliability and safety characteristics of nuclear systems. Qualitative analysis of system logic models, i.e., models couched in an event (Boolean) algebra, is defined, and the advantages inherent in qualitative analysis are explained. Certain qualitative procedures that were developed as a part of fault-tree analysis are presented for illustration. Five fault-tree analysis computer-programs that contain a qualitative procedure for determining minimal cut sets are surveyed. For each program the minimal cut-set algorithm and limitations on its use are described. The recently developed common-cause analysis for studying the effect of common-causes of failure on system behavior is explained. This qualitative procedure does not require altering the fault tree, but does use minimal cut sets from the fault tree as part of its input. The method is applied using two different computer programs. 25 refs

  18. Prime implicants in dynamic reliability analysis

    International Nuclear Information System (INIS)

    Tyrväinen, Tero

    2016-01-01

    This paper develops an improved definition of a prime implicant for the needs of dynamic reliability analysis. Reliability analyses often aim to identify minimal cut sets or prime implicants, which are minimal conditions that cause an undesired top event, such as a system's failure. Dynamic reliability analysis methods take the time-dependent behaviour of a system into account. This means that the state of a component can change in the analysed time frame and prime implicants can include the failure of a component at different time points. There can also be dynamic constraints on a component's behaviour. For example, a component can be non-repairable in the given time frame. If a non-repairable component needs to be failed at a certain time point to cause the top event, we consider that the condition that it is failed at the latest possible time point is minimal, and the condition in which it fails earlier non-minimal. The traditional definition of a prime implicant does not account for this type of time-related minimality. In this paper, a new definition is introduced and illustrated using a dynamic flowgraph methodology model. - Highlights: • A new definition of a prime implicant is developed for dynamic reliability analysis. • The new definition takes time-related minimality into account. • The new definition is needed in dynamic flowgraph methodology. • Results can be represented by a smaller number of prime implicants.

  19. Reliability models for Space Station power system

    Science.gov (United States)

    Singh, C.; Patton, A. D.; Kim, Y.; Wagner, H.

    1987-01-01

    This paper presents a methodology for the reliability evaluation of Space Station power system. The two options considered are the photovoltaic system and the solar dynamic system. Reliability models for both of these options are described along with the methodology for calculating the reliability indices.

  20. PREP KITT, System Reliability by Fault Tree Analysis. PREP, Min Path Set and Min Cut Set for Fault Tree Analysis, Monte-Carlo Method. KITT, Component and System Reliability Information from Kinetic Fault Tree Theory

    International Nuclear Information System (INIS)

    Vesely, W.E.; Narum, R.E.

    1997-01-01

    1 - Description of problem or function: The PREP/KITT computer program package obtains system reliability information from a system fault tree. The PREP program finds the minimal cut sets and/or the minimal path sets of the system fault tree. (A minimal cut set is a smallest set of components such that if all the components are simultaneously failed the system is failed. A minimal path set is a smallest set of components such that if all of the components are simultaneously functioning the system is functioning.) The KITT programs determine reliability information for the components of each minimal cut or path set, for each minimal cut or path set, and for the system. Exact, time-dependent reliability information is determined for each component and for each minimal cut set or path set. For the system, reliability results are obtained by upper bound approximations or by a bracketing procedure in which various upper and lower bounds may be obtained as close to one another as desired. The KITT programs can handle independent components which are non-repairable or which have a constant repair time. Any assortment of non-repairable components and components having constant repair times can be considered. Any inhibit conditions having constant probabilities of occurrence can be handled. The failure intensity of each component is assumed to be constant with respect to time. The KITT2 program can also handle components which during different time intervals, called phases, may have different reliability properties. 2 - Method of solution: The PREP program obtains minimal cut sets by either direct deterministic testing or by an efficient Monte Carlo algorithm. The minimal path sets are obtained using the Monte Carlo algorithm. The reliability information is obtained by the KITT programs from numerical solution of the simple integral balance equations of kinetic tree theory. 3 - Restrictions on the complexity of the problem: The PREP program will obtain the minimal cut and

  1. Human reliability analysis of control room operators

    Energy Technology Data Exchange (ETDEWEB)

    Santos, Isaac J.A.L.; Carvalho, Paulo Victor R.; Grecco, Claudio H.S. [Instituto de Engenharia Nuclear (IEN), Rio de Janeiro, RJ (Brazil)

    2005-07-01

    Human reliability is the probability that a person correctly performs some system required action in a required time period and performs no extraneous action that can degrade the system Human reliability analysis (HRA) is the analysis, prediction and evaluation of work-oriented human performance using some indices as human error likelihood and probability of task accomplishment. Significant progress has been made in the HRA field during the last years, mainly in nuclear area. Some first-generation HRA methods were developed, as THERP (Technique for human error rate prediction). Now, an array of called second-generation methods are emerging as alternatives, for instance ATHEANA (A Technique for human event analysis). The ergonomics approach has as tool the ergonomic work analysis. It focus on the study of operator's activities in physical and mental form, considering at the same time the observed characteristics of operator and the elements of the work environment as they are presented to and perceived by the operators. The aim of this paper is to propose a methodology to analyze the human reliability of the operators of industrial plant control room, using a framework that includes the approach used by ATHEANA, THERP and the work ergonomics analysis. (author)

  2. The quantitative failure of human reliability analysis

    Energy Technology Data Exchange (ETDEWEB)

    Bennett, C.T.

    1995-07-01

    This philosophical treatise argues the merits of Human Reliability Analysis (HRA) in the context of the nuclear power industry. Actually, the author attacks historic and current HRA as having failed in informing policy makers who make decisions based on risk that humans contribute to systems performance. He argues for an HRA based on Bayesian (fact-based) inferential statistics, which advocates a systems analysis process that employs cogent heuristics when using opinion, and tempers itself with a rational debate over the weight given subjective and empirical probabilities.

  3. Passive System Reliability Towards Efficient Methodology

    International Nuclear Information System (INIS)

    Sarathy, U. Partha; Arul, A. John; Ramakrishnan, M.

    2011-01-01

    Passive System Reliability-Features/Methods: ♦ Passive System: No pumps, no valves, no human intervention, no signals. Passive System Reliability: ♦ Depends only on functionality or inherent robustness of the process and design. ♦ Since active equipment is absent, reliability of functionality is the dominant factor. ♦ Various causes like uncertainty in design and critical parameters, design process, environment etc. needs to be accounted. ♦ Quantification methodology is uncertainty propagation and estimation of nominal failure probability (as in structural reliability studies)

  4. Reliability assessment of nuclear structural systems

    International Nuclear Information System (INIS)

    Reich, M.; Hwang, H.

    1983-01-01

    Reliability assessment of nuclear structural systems has been receiving more emphasis over the last few years. This paper deals with the recent progress made by the Structural Analysis Division of Brookhaven National Laboratory (BNL), in the development of a probability-based reliability analysis methodology for safety evaluation of reactor containments and other seismic category I structures. An important feature of this methodology is the incorporation of finite element analysis and random vibration theory. By utilizing this method, it is possible to evaluate the safety of nuclear structures under various static and dynamic loads in terms of limit state probability. Progress in other related areas, such as the establishment of probabilistic characteristics for various loads and structural resistance, are also described. Results of an application of the methodology to a realistic reinforced concrete containment subjected to dead and live loads, accidental internal pressures and earthquake ground accelerations are presented

  5. A study of digital hardware architectures for nuclear reactors protection systems applications - reliability and safety analysis methods

    International Nuclear Information System (INIS)

    Benko, Pedro Luiz

    1997-01-01

    A study of digital hardware architectures, including experience in many countries, topologies and solutions to interface circuits for protection systems of nuclear reactors is presented. Methods for developing digital systems architectures based on fault tolerant and safety requirements is proposed. Directives for assessing such conditions are suggested. Techniques and the most common tools employed in reliability, safety evaluation and modeling of hardware architectures is also presented. Markov chain modeling is used to evaluate the reliability of redundant architectures. In order to estimate software quality, several mechanisms to be used in design, specification, and validation and verification (V and V) procedures are suggested. A digital protection system architecture has been analyzed as a case study. (author)

  6. Reliability and concurrent validity of a Smartphone, bubble inclinometer and motion analysis system for measurement of hip joint range of motion.

    Science.gov (United States)

    Charlton, Paula C; Mentiplay, Benjamin F; Pua, Yong-Hao; Clark, Ross A

    2015-05-01

    Traditional methods of assessing joint range of motion (ROM) involve specialized tools that may not be widely available to clinicians. This study assesses the reliability and validity of a custom Smartphone application for assessing hip joint range of motion. Intra-tester reliability with concurrent validity. Passive hip joint range of motion was recorded for seven different movements in 20 males on two separate occasions. Data from a Smartphone, bubble inclinometer and a three dimensional motion analysis (3DMA) system were collected simultaneously. Intraclass correlation coefficients (ICCs), coefficients of variation (CV) and standard error of measurement (SEM) were used to assess reliability. To assess validity of the Smartphone application and the bubble inclinometer against the three dimensional motion analysis system, intraclass correlation coefficients and fixed and proportional biases were used. The Smartphone demonstrated good to excellent reliability (ICCs>0.75) for four out of the seven movements, and moderate to good reliability for the remaining three movements (ICC=0.63-0.68). Additionally, the Smartphone application displayed comparable reliability to the bubble inclinometer. The Smartphone application displayed excellent validity when compared to the three dimensional motion analysis system for all movements (ICCs>0.88) except one, which displayed moderate to good validity (ICC=0.71). Smartphones are portable and widely available tools that are mostly reliable and valid for assessing passive hip range of motion, with potential for large-scale use when a bubble inclinometer is not available. However, caution must be taken in its implementation as some movement axes demonstrated only moderate reliability. Copyright © 2014 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

  7. Fatigue Reliability Analysis of a Mono-Tower Platform

    DEFF Research Database (Denmark)

    Kirkegaard, Poul Henning; Sørensen, John Dalsgaard; Brincker, Rune

    1991-01-01

    In this paper, a fatigue reliability analysis of a Mono-tower platform is presented. The failure mode, fatigue failure in the butt welds, is investigated with two different models. The one with the fatigue strength expressed through SN relations, the other with the fatigue strength expressed...... through linear-elastic fracture mechanics (LEFM). In determining the cumulative fatigue damage, Palmgren-Miner's rule is applied. Element reliability, as well as systems reliability, is estimated using first-order reliability methods (FORM). The sensitivity of the systems reliability to various parameters...... is investigated. The systems reliability index, estimated by using the fatigue elements with the fatigue strength expressed through SN relations, is found to be smaller than the systems reliability index estimated by using LEFM. It is shown that the systems reliability index is very sensitive to variations...

  8. Reliability program requirements for aeronautical and space system contractors

    Science.gov (United States)

    1987-01-01

    General reliability program requirements for NASA contracts involving the design, development, fabrication, test, and/or use of aeronautical and space systems including critical ground support equipment are prescribed. The reliability program requirements require (1) thorough planning and effective management of the reliability effort; (2) definition of the major reliability tasks and their place as an integral part of the design and development process; (3) planning and evaluating the reliability of the system and its elements (including effects of software interfaces) through a program of analysis, review, and test; and (4) timely status indication by formal documentation and other reporting to facilitate control of the reliability program.

  9. Weibull distribution in reliability data analysis in nuclear power plant

    International Nuclear Information System (INIS)

    Ma Yingfei; Zhang Zhijian; Zhang Min; Zheng Gangyang

    2015-01-01

    Reliability is an important issue affecting each stage of the life cycle ranging from birth to death of a product or a system. The reliability engineering includes the equipment failure data processing, quantitative assessment of system reliability and maintenance, etc. Reliability data refers to the variety of data that describe the reliability of system or component during its operation. These data may be in the form of numbers, graphics, symbols, texts and curves. Quantitative reliability assessment is the task of the reliability data analysis. It provides the information related to preventing, detect, and correct the defects of the reliability design. Reliability data analysis under proceed with the various stages of product life cycle and reliability activities. Reliability data of Systems Structures and Components (SSCs) in Nuclear Power Plants is the key factor of probabilistic safety assessment (PSA); reliability centered maintenance and life cycle management. The Weibull distribution is widely used in reliability engineering, failure analysis, industrial engineering to represent manufacturing and delivery times. It is commonly used to model time to fail, time to repair and material strength. In this paper, an improved Weibull distribution is introduced to analyze the reliability data of the SSCs in Nuclear Power Plants. An example is given in the paper to present the result of the new method. The Weibull distribution of mechanical equipment for reliability data fitting ability is very strong in nuclear power plant. It's a widely used mathematical model for reliability analysis. The current commonly used methods are two-parameter and three-parameter Weibull distribution. Through comparison and analysis, the three-parameter Weibull distribution fits the data better. It can reflect the reliability characteristics of the equipment and it is more realistic to the actual situation. (author)

  10. Software Architecture Reliability Analysis using Failure Scenarios

    NARCIS (Netherlands)

    Tekinerdogan, B.; Sözer, Hasan; Aksit, Mehmet

    With the increasing size and complexity of software in embedded systems, software has now become a primary threat for the reliability. Several mature conventional reliability engineering techniques exist in literature but traditionally these have primarily addressed failures in hardware components

  11. Advances in reliability and system engineering

    CERN Document Server

    Davim, J

    2017-01-01

    This book presents original studies describing the latest research and developments in the area of reliability and systems engineering. It helps the reader identifying gaps in the current knowledge and presents fruitful areas for further research in the field. Among others, this book covers reliability measures, reliability assessment of multi-state systems, optimization of multi-state systems, continuous multi-state systems, new computational techniques applied to multi-state systems and probabilistic and non-probabilistic safety assessment.

  12. Reliability analysis using network simulation

    International Nuclear Information System (INIS)

    Engi, D.

    1985-01-01

    The models that can be used to provide estimates of the reliability of nuclear power systems operate at many different levels of sophistication. The least-sophisticated models treat failure processes that entail only time-independent phenomena (such as demand failure). More advanced models treat processes that also include time-dependent phenomena such as run failure and possibly repair. However, many of these dynamic models are deficient in some respects because they either disregard the time-dependent phenomena that cannot be expressed in closed-form analytic terms or because they treat these phenomena in quasi-static terms. The next level of modeling requires a dynamic approach that incorporates not only procedures for treating all significant time-dependent phenomena but also procedures for treating these phenomena when they are conditionally linked or characterized by arbitrarily selected probability distributions. The level of sophistication that is required is provided by a dynamic, Monte Carlo modeling approach. A computer code that uses a dynamic, Monte Carlo modeling approach is Q-GERT (Graphical Evaluation and Review Technique - with Queueing), and the present study had demonstrated the feasibility of using Q-GERT for modeling time-dependent, unconditionally and conditionally linked phenomena that are characterized by arbitrarily selected probability distributions

  13. Reliability analysis with Bayesian networks

    OpenAIRE

    Zwirglmaier, Kilian Martin

    2017-01-01

    Bayesian networks (BNs) represent a probabilistic modeling tool with large potential for reliability engineering. While BNs have been successfully applied to reliability engineering, there are remaining issues, some of which are addressed in this work. Firstly a classification of BN elicitation approaches is proposed. Secondly two approximate inference approaches, one of which is based on discretization and the other one on sampling, are proposed. These approaches are applicable to hybrid/con...

  14. Cost analysis of reliability investigations

    International Nuclear Information System (INIS)

    Schmidt, F.

    1981-01-01

    Taking Epsteins testing theory as a basis, premisses are formulated for the selection of cost-optimized reliability inspection plans. Using an example, the expected testing costs and inspection time periods of various inspection plan types, standardized on the basis of the exponential distribution, are compared. It can be shown that sequential reliability tests usually involve lower costs than failure or time-fixed tests. The most 'costly' test is to be expected with the inspection plan type NOt. (orig.) [de

  15. Sensitivity analysis in a structural reliability context

    International Nuclear Information System (INIS)

    Lemaitre, Paul

    2014-01-01

    This thesis' subject is sensitivity analysis in a structural reliability context. The general framework is the study of a deterministic numerical model that allows to reproduce a complex physical phenomenon. The aim of a reliability study is to estimate the failure probability of the system from the numerical model and the uncertainties of the inputs. In this context, the quantification of the impact of the uncertainty of each input parameter on the output might be of interest. This step is called sensitivity analysis. Many scientific works deal with this topic but not in the reliability scope. This thesis' aim is to test existing sensitivity analysis methods, and to propose more efficient original methods. A bibliographical step on sensitivity analysis on one hand and on the estimation of small failure probabilities on the other hand is first proposed. This step raises the need to develop appropriate techniques. Two variables ranking methods are then explored. The first one proposes to make use of binary classifiers (random forests). The second one measures the departure, at each step of a subset method, between each input original density and the density given the subset reached. A more general and original methodology reflecting the impact of the input density modification on the failure probability is then explored. The proposed methods are then applied on the CWNR case, which motivates this thesis. (author)

  16. Reliability analysis of an extreme ultraviolet spectrometer for space research

    International Nuclear Information System (INIS)

    Chakrabarti, S.

    1980-01-01

    A method of reliability analysis of a complex system is reviewed. Key concepts are explained with examples. A reliability analysis of an extreme ultraviolet (EUV) spectrometer flown on February 24, 1979, is carried out using this method. The results of this analysis are presented with their interpretation. (orig.)

  17. Concept of Korean reliability qualification system

    International Nuclear Information System (INIS)

    Kim, Hyoung Eui

    2008-01-01

    It has been passed eight years since Reliability Assessment Centers of 18 fields including machinery and electronic field were established in 2000 to enhance the reliability of components and materials which are foundation of domestic industry. When Reliability Assessment Center were established in 2000, many questions and issues have been headed. Those questions and issues were how reliability and quality are different, how the reliability measurement can be expressed, how the reliability requirements can be made, how the reliability of components can be tested and evaluated and etc. Currently it is the state that the controversy and improvement methods about reliability qualification, no failure test and one failure acceptance test were issued. This paper investigates the problems toward test and evaluation methods to certificate R-Mark and presents the direction of Korean Reliability Certification System

  18. Mass and Reliability System (MaRS)

    Science.gov (United States)

    Barnes, Sarah

    2016-01-01

    The Safety and Mission Assurance (S&MA) Directorate is responsible for mitigating risk, providing system safety, and lowering risk for space programs from ground to space. The S&MA is divided into 4 divisions: The Space Exploration Division (NC), the International Space Station Division (NE), the Safety & Test Operations Division (NS), and the Quality and Flight Equipment Division (NT). The interns, myself and Arun Aruljothi, will be working with the Risk & Reliability Analysis Branch under the NC Division's. The mission of this division is to identify, characterize, diminish, and communicate risk by implementing an efficient and effective assurance model. The team utilizes Reliability and Maintainability (R&M) and Probabilistic Risk Assessment (PRA) to ensure decisions concerning risks are informed, vehicles are safe and reliable, and program/project requirements are realistic and realized. This project pertains to the Orion mission, so it is geared toward a long duration Human Space Flight Program(s). For space missions, payload is a critical concept; balancing what hardware can be replaced by components verse by Orbital Replacement Units (ORU) or subassemblies is key. For this effort a database was created that combines mass and reliability data, called Mass and Reliability System or MaRS. The U.S. International Space Station (ISS) components are used as reference parts in the MaRS database. Using ISS components as a platform is beneficial because of the historical context and the environment similarities to a space flight mission. MaRS uses a combination of systems: International Space Station PART for failure data, Vehicle Master Database (VMDB) for ORU & components, Maintenance & Analysis Data Set (MADS) for operation hours and other pertinent data, & Hardware History Retrieval System (HHRS) for unit weights. MaRS is populated using a Visual Basic Application. Once populated, the excel spreadsheet is comprised of information on ISS components including

  19. Reliability analysis with the simulator S.ESCAF of a very complex sequential system: the electrical power supply system of a nuclear reactor

    International Nuclear Information System (INIS)

    Blot, M.

    1987-06-01

    The reliability analysis of complex sequential systems, in which the order of arrival of the events must be taken into account, can be very difficult, because the use of the classical modelling technique of Markov diagrams leads to an important limitation on the number of components which can be handled. The desk-top apparatus S.ESCAF, which electronically simulates very closely the behaviour of the system being studied, and is very easy to use, even by a non specialist in electronics, allows one to avoid these inconveniences and to enlarge considerably the analysis possibilities. This paper shows the application of the S.ESCAF method to the electrical power supply system of a nuclear reactor. This system requires the simulation of more than forty components with about sixty events such as failure, repair and refusal to start. A comparison of times necessary to perform the analysis by these means and by other methods is described, and the advantages of S.ESCAF are presented

  20. System reliability effects in wind turbine blades

    DEFF Research Database (Denmark)

    Dimitrov, Nikolay Krasimirov; Friis-Hansen, Peter; Berggreen, Christian

    2012-01-01

    from reliability point of view. The present paper discusses the specifics of system reliability behavior of laminated composite sandwich panels, and solves an example system reliability problem for a glass fiber-reinforced composite sandwich structure subjected to in-plane compression.......Laminated composite sandwich panels have a layered structure, where individual layers have randomly varying stiffness and strength properties. The presence of multiple failure modes and load redistribution following partial failures are the reason for laminated composites to exhibit system behavior...

  1. Reliability Analysis of Money Habitudes

    Science.gov (United States)

    Delgadillo, Lucy M.; Bushman, Brittani S.

    2015-01-01

    Use of the Money Habitudes exercise has gained popularity among various financial professionals. This article reports on the reliability of this resource. A survey administered to young adults at a western state university was conducted, and each Habitude or "domain" was analyzed using Cronbach's alpha procedures. Results showed all six…

  2. Subset simulation for structural reliability sensitivity analysis

    International Nuclear Information System (INIS)

    Song Shufang; Lu Zhenzhou; Qiao Hongwei

    2009-01-01

    Based on two procedures for efficiently generating conditional samples, i.e. Markov chain Monte Carlo (MCMC) simulation and importance sampling (IS), two reliability sensitivity (RS) algorithms are presented. On the basis of reliability analysis of Subset simulation (Subsim), the RS of the failure probability with respect to the distribution parameter of the basic variable is transformed as a set of RS of conditional failure probabilities with respect to the distribution parameter of the basic variable. By use of the conditional samples generated by MCMC simulation and IS, procedures are established to estimate the RS of the conditional failure probabilities. The formulae of the RS estimator, its variance and its coefficient of variation are derived in detail. The results of the illustrations show high efficiency and high precision of the presented algorithms, and it is suitable for highly nonlinear limit state equation and structural system with single and multiple failure modes

  3. Towards Reliable Integrated Services for Dependable Systems

    DEFF Research Database (Denmark)

    Schiøler, Henrik; Ravn, Anders Peter; Izadi-Zamanabadi, Roozbeh

    2003-01-01

    Reliability issues for various technical systems are discussed and focus is directed towards distributed systems, where communication facilities are vital to maintain system functionality. Reliability in communication subsystems is considered as a resource to be shared among a number of logical c...

  4. Human reliability in complex systems: an overview

    International Nuclear Information System (INIS)

    Embrey, D.E.

    1976-07-01

    A detailed analysis is presented of the main conceptual background underlying the areas of human reliability and human error. The concept of error is examined and generalized to that of human reliability, and some of the practical and methodological difficulties of reconciling the different standpoints of the human factors specialist and the engineer discussed. Following a survey of general reviews available on human reliability, quantitative techniques for prediction of human reliability are considered. An in-depth critical analysis of the various quantitative methods is then presented, together with the data bank requirements for human reliability prediction. Reliability considerations in process control and nuclear plant, and also areas of design, maintenance, testing and emergency situations are discussed. The effects of stress on human reliability are analysed and methods of minimizing these effects discussed. Finally, a summary is presented and proposals for further research are set out. (author)

  5. PV Systems Reliability Final Technical Report.

    Energy Technology Data Exchange (ETDEWEB)

    Lavrova, Olga [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Flicker, Jack David [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Johnson, Jay [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Armijo, Kenneth Miguel [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Gonzalez, Sigifredo [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Schindelholz, Eric John [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Sorensen, Neil R. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Yang, Benjamin Bing-Yeh [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2015-12-01

    The continued exponential growth of photovoltaic technologies paves a path to a solar-powered world, but requires continued progress toward low-cost, high-reliability, high-performance photovoltaic (PV) systems. High reliability is an essential element in achieving low-cost solar electricity by reducing operation and maintenance (O&M) costs and extending system lifetime and availability, but these attributes are difficult to verify at the time of installation. Utilities, financiers, homeowners, and planners are demanding this information in order to evaluate their financial risk as a prerequisite to large investments. Reliability research and development (R&D) is needed to build market confidence by improving product reliability and by improving predictions of system availability, O&M cost, and lifetime. This project is focused on understanding, predicting, and improving the reliability of PV systems. The two areas being pursued include PV arc-fault and ground fault issues, and inverter reliability.

  6. Solid State Lighting Reliability Components to Systems

    CERN Document Server

    Fan, XJ

    2013-01-01

    Solid State Lighting Reliability: Components to Systems begins with an explanation of the major benefits of solid state lighting (SSL) when compared to conventional lighting systems including but not limited to long useful lifetimes of 50,000 (or more) hours and high efficacy. When designing effective devices that take advantage of SSL capabilities the reliability of internal components (optics, drive electronics, controls, thermal design) take on critical importance. As such a detailed discussion of reliability from performance at the device level to sub components is included as well as the integrated systems of SSL modules, lamps and luminaires including various failure modes, reliability testing and reliability performance. This book also: Covers the essential reliability theories and practices for current and future development of Solid State Lighting components and systems Provides a systematic overview for not only the state-of-the-art, but also future roadmap and perspectives of Solid State Lighting r...

  7. Mechanical system reliability for long life space systems

    Science.gov (United States)

    Kowal, Michael T.

    1994-01-01

    The creation of a compendium of mechanical limit states was undertaken in order to provide a reference base for the application of first-order reliability methods to mechanical systems in the context of the development of a system level design methodology. The compendium was conceived as a reference source specific to the problem of developing the noted design methodology, and not an exhaustive or exclusive compilation of mechanical limit states. The compendium is not intended to be a handbook of mechanical limit states for general use. The compendium provides a diverse set of limit-state relationships for use in demonstrating the application of probabilistic reliability methods to mechanical systems. The compendium is to be used in the reliability analysis of moderately complex mechanical systems.

  8. Reliability of large and complex systems

    CERN Document Server

    Kolowrocki, Krzysztof

    2014-01-01

    Reliability of Large and Complex Systems, previously titled Reliability of Large Systems, is an innovative guide to the current state and reliability of large and complex systems. In addition to revised and updated content on the complexity and safety of large and complex mechanisms, this new edition looks at the reliability of nanosystems, a key research topic in nanotechnology science. The author discusses the importance of safety investigation of critical infrastructures that have aged or have been exposed to varying operational conditions. This reference provides an asympt

  9. Reliability of Power Electronic Converter Systems

    DEFF Research Database (Denmark)

    electronic converter systems; anomaly detection and remaining-life prediction for power electronics; reliability of DC-link capacitors in power electronic converters; reliability of power electronics packaging; modeling for life-time prediction of power semiconductor modules; minimization of DC......-tolerant adjustable speed drive systems; mission profile oriented reliability design in wind turbine and photovoltaic systems; reliability of power conversion systems in photovoltaic applications; power supplies for computers; and high-power converters. Reliability of Power Electronic Converter Systems is essential......The main aims of power electronic converter systems (PECS) are to control, convert, and condition electrical power flow from one form to another through the use of solid-state electronics. This book outlines current research into the scientific modeling, experimentation, and remedial measures...

  10. Reliability analysis of reactor pressure vessel intensity

    International Nuclear Information System (INIS)

    Zheng Liangang; Lu Yongbo

    2012-01-01

    This paper performs the reliability analysis of reactor pressure vessel (RPV) with ANSYS. The analysis method include direct Monte Carlo Simulation method, Latin Hypercube Sampling, central composite design and Box-Behnken Matrix design. The RPV integrity reliability under given input condition is proposed. The result shows that the effects on the RPV base material reliability are internal press, allowable basic stress and elasticity modulus of base material in descending order, and the effects on the bolt reliability are allowable basic stress of bolt material, preload of bolt and internal press in descending order. (authors)

  11. Reliability of dynamic systems under limited information.

    Energy Technology Data Exchange (ETDEWEB)

    Field, Richard V., Jr. (.,; .); Grigoriu, Mircea

    2006-09-01

    A method is developed for reliability analysis of dynamic systems under limited information. The available information includes one or more samples of the system output; any known information on features of the output can be used if available. The method is based on the theory of non-Gaussian translation processes and is shown to be particularly suitable for problems of practical interest. For illustration, we apply the proposed method to a series of simple example problems and compare with results given by traditional statistical estimators in order to establish the accuracy of the method. It is demonstrated that the method delivers accurate results for the case of linear and nonlinear dynamic systems, and can be applied to analyze experimental data and/or mathematical model outputs. Two complex applications of direct interest to Sandia are also considered. First, we apply the proposed method to assess design reliability of a MEMS inertial switch. Second, we consider re-entry body (RB) component vibration response during normal re-entry, where the objective is to estimate the time-dependent probability of component failure. This last application is directly relevant to re-entry random vibration analysis at Sandia, and may provide insights on test-based and/or model-based qualification of weapon components for random vibration environments.

  12. User's guide to the Reliability Estimation System Testbed (REST)

    Science.gov (United States)

    Nicol, David M.; Palumbo, Daniel L.; Rifkin, Adam

    1992-01-01

    The Reliability Estimation System Testbed is an X-window based reliability modeling tool that was created to explore the use of the Reliability Modeling Language (RML). RML was defined to support several reliability analysis techniques including modularization, graphical representation, Failure Mode Effects Simulation (FMES), and parallel processing. These techniques are most useful in modeling large systems. Using modularization, an analyst can create reliability models for individual system components. The modules can be tested separately and then combined to compute the total system reliability. Because a one-to-one relationship can be established between system components and the reliability modules, a graphical user interface may be used to describe the system model. RML was designed to permit message passing between modules. This feature enables reliability modeling based on a run time simulation of the system wide effects of a component's failure modes. The use of failure modes effects simulation enhances the analyst's ability to correctly express system behavior when using the modularization approach to reliability modeling. To alleviate the computation bottleneck often found in large reliability models, REST was designed to take advantage of parallel processing on hypercube processors.

  13. Reliability Analysis of Adhesive Bonded Scarf Joints

    DEFF Research Database (Denmark)

    Kimiaeifar, Amin; Toft, Henrik Stensgaard; Lund, Erik

    2012-01-01

    A probabilistic model for the reliability analysis of adhesive bonded scarfed lap joints subjected to static loading is developed. It is representative for the main laminate in a wind turbine blade subjected to flapwise bending. The structural analysis is based on a three dimensional (3D) finite...... element analysis (FEA). For the reliability analysis a design equation is considered which is related to a deterministic code-based design equation where reliability is secured by partial safety factors together with characteristic values for the material properties and loads. The failure criteria...... are formulated using a von Mises, a modified von Mises and a maximum stress failure criterion. The reliability level is estimated for the scarfed lap joint and this is compared with the target reliability level implicitly used in the wind turbine standard IEC 61400-1. A convergence study is performed to validate...

  14. Time domain series system definition and gear set reliability modeling

    International Nuclear Information System (INIS)

    Xie, Liyang; Wu, Ningxiang; Qian, Wenxue

    2016-01-01

    Time-dependent multi-configuration is a typical feature for mechanical systems such as gear trains and chain drives. As a series system, a gear train is distinct from a traditional series system, such as a chain, in load transmission path, system-component relationship, system functioning manner, as well as time-dependent system configuration. Firstly, the present paper defines time-domain series system to which the traditional series system reliability model is not adequate. Then, system specific reliability modeling technique is proposed for gear sets, including component (tooth) and subsystem (tooth-pair) load history description, material priori/posterior strength expression, time-dependent and system specific load-strength interference analysis, as well as statistically dependent failure events treatment. Consequently, several system reliability models are developed for gear sets with different tooth numbers in the scenario of tooth root material ultimate tensile strength failure. The application of the models is discussed in the last part, and the differences between the system specific reliability model and the traditional series system reliability model are illustrated by virtue of several numerical examples. - Highlights: • A new type of series system, i.e. time-domain multi-configuration series system is defined, that is of great significance to reliability modeling. • Multi-level statistical analysis based reliability modeling method is presented for gear transmission system. • Several system specific reliability models are established for gear set reliability estimation. • The differences between the traditional series system reliability model and the new model are illustrated.

  15. Computer system reliability safety and usability

    CERN Document Server

    Dhillon, BS

    2013-01-01

    Computer systems have become an important element of the world economy, with billions of dollars spent each year on development, manufacture, operation, and maintenance. Combining coverage of computer system reliability, safety, usability, and other related topics into a single volume, Computer System Reliability: Safety and Usability eliminates the need to consult many different and diverse sources in the hunt for the information required to design better computer systems.After presenting introductory aspects of computer system reliability such as safety, usability-related facts and figures,

  16. Digital Processor Module Reliability Analysis of Nuclear Power Plant

    International Nuclear Information System (INIS)

    Lee, Sang Yong; Jung, Jae Hyun; Kim, Jae Ho; Kim, Sung Hun

    2005-01-01

    The system used in plant, military equipment, satellite, etc. consists of many electronic parts as control module, which requires relatively high reliability than other commercial electronic products. Specially, Nuclear power plant related to the radiation safety requires high safety and reliability, so most parts apply to Military-Standard level. Reliability prediction method provides the rational basis of system designs and also provides the safety significance of system operations. Thus various reliability prediction tools have been developed in recent decades, among of them, the MI-HDBK-217 method has been widely used as a powerful tool for the prediction. In this work, It is explained that reliability analysis work for Digital Processor Module (DPM, control module of SMART) is performed by Parts Stress Method based on MIL-HDBK-217F NOTICE2. We are using the Relex 7.6 of Relex software corporation, because reliability analysis process requires enormous part libraries and data for failure rate calculation

  17. Reliability-Based Robustness Analysis for a Croatian Sports Hall

    DEFF Research Database (Denmark)

    Čizmar, Dean; Kirkegaard, Poul Henning; Sørensen, John Dalsgaard

    2011-01-01

    This paper presents a probabilistic approach for structural robustness assessment for a timber structure built a few years ago. The robustness analysis is based on a structural reliability based framework for robustness and a simplified mechanical system modelling of a timber truss system...... is expressed and evaluated by a robustness index. Next, the robustness is assessed using system reliability indices where the probabilistic failure model is modelled by a series system of parallel systems....

  18. Reliability of power electronic converter systems

    CERN Document Server

    Chung, Henry Shu-hung; Blaabjerg, Frede; Pecht, Michael

    2016-01-01

    This book outlines current research into the scientific modeling, experimentation, and remedial measures for advancing the reliability, availability, system robustness, and maintainability of Power Electronic Converter Systems (PECS) at different levels of complexity.

  19. Inter-rater reliability and double reading analysis of an automated three-dimensional breast ultrasound system: comparison of two independent examiners.

    Science.gov (United States)

    Maier, Anna; Heil, Joerg; Lauer, Anna; Harcos, Aba; Schaefgen, Benedikt; von Au, Alexandra; Spratte, Julia; Riedel, Fabian; Rauch, Geraldine; Hennigs, André; Domschke, Christoph; Schott, Sarah; Rom, Joachim; Schuetz, Florian; Sohn, Christof; Golatta, Michael

    2017-07-26

    Breast ultrasound could be a valuable tool complementary to mammography in breast cancer screening. Automated 3D breast ultrasound (ABUS) addresses challenges of hand-held ultrasound and could allow double reading analysis of ultrasound images. This trial assesses the inter-rater reliability and double reading analysis of an ABUS system. To assess the reproducibility and diagnostic validity of the ABUS system, SomoV™, a blinded double reading analysis, was performed in 1019 patients (2038 breasts) by two examiners (examiner A/B) and compared to single reading results, as well as to the reference standard regarding its diagnostic validity. Cohen's kappa coefficients were calculated to measure the inter-rater reliability and agreement of the different diagnostic modalities. Patient comfort and time consumption for image acquisition and reading were analyzed descriptively as secondary objectives. Analysis of inter-rater reliability yielded agreement in 81.6% (κ = 0.37; p reading analysis of SomoV™ exams (examiner A/examiner B) compared to reference standard showed good specificity (examiner A: 88.3%/examiner B: 84.5%), fair inter-rater agreement (examiner A: κ = 0.31/examiner B: κ = 0.31), and adequate sensitivity (examiner A: 53.1%/examiner B: 64.2%). Double reading analysis yielded good sensitivity and specificity (73.7 and 77.7%). Mammography (n = 1911) alone detected 160 of 176 carcinomas (sensitivity 90.1%). Adding SomoV™ to mammography would have detected 12 additional carcinomas, resulting in a higher sensitivity of 97.7%. SomoV™ is a promising technique with good sensitivity, high patient comfort, and fair inter-examiner reliability. It allows double reading analysis that, in combination with mammography, could increase detection rates in breast cancer screening.

  20. Telecommunications system reliability engineering theory and practice

    CERN Document Server

    Ayers, Mark L

    2012-01-01

    "Increasing system complexity require new, more sophisticated tools for system modeling and metric calculation. Bringing the field up to date, this book provides telecommunications engineers with practical tools for analyzing, calculating, and reporting availability, reliability, and maintainability metrics. It gives the background in system reliability theory and covers in-depth applications in fiber optic networks, microwave networks, satellite networks, power systems, and facilities management. Computer programming tools for simulating the approaches presented, using the Matlab software suite, are also provided"

  1. 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

  2. The contribution of instrumentation and control software to system reliability

    International Nuclear Information System (INIS)

    Fryer, M.O.

    1984-01-01

    Advanced instrumentation and control systems are usually implemented using computers that monitor the instrumentation and issue commands to control elements. The control commands are based on instrument readings and software control logic. The reliability of the total system will be affected by the software design. When comparing software designs, an evaluation of how each design can contribute to the reliability of the system is desirable. Unfortunately, the science of reliability assessment of combined hardware and software systems is in its infancy. Reliability assessment of combined hardware/software systems is often based on over-simplified assumptions about software behavior. A new method of reliability assessment of combined software/hardware systems is presented. The method is based on a procedure called fault tree analysis which determines how component failures can contribute to system failure. Fault tree analysis is a well developed method for reliability assessment of hardware systems and produces quantitative estimates of failure probability based on component failure rates. It is shown how software control logic can be mapped into a fault tree that depicts both software and hardware contributions to system failure. The new method is important because it provides a way for quantitatively evaluating the reliability contribution of software designs. In many applications, this can help guide designers in producing safer and more reliable systems. An application to the nuclear power research industry is discussed

  3. Human Reliability Analysis for Design: Using Reliability Methods for Human Factors Issues

    Energy Technology Data Exchange (ETDEWEB)

    Ronald Laurids Boring

    2010-11-01

    This paper reviews the application of human reliability analysis methods to human factors design issues. An application framework is sketched in which aspects of modeling typically found in human reliability analysis are used in a complementary fashion to the existing human factors phases of design and testing. The paper provides best achievable practices for design, testing, and modeling. Such best achievable practices may be used to evaluate and human system interface in the context of design safety certifications.

  4. Human Reliability Analysis for Design: Using Reliability Methods for Human Factors Issues

    International Nuclear Information System (INIS)

    Boring, Ronald Laurids

    2010-01-01

    This paper reviews the application of human reliability analysis methods to human factors design issues. An application framework is sketched in which aspects of modeling typically found in human reliability analysis are used in a complementary fashion to the existing human factors phases of design and testing. The paper provides best achievable practices for design, testing, and modeling. Such best achievable practices may be used to evaluate and human system interface in the context of design safety certifications.

  5. Description of the TREBIL, CRESSEX and STREUSL computer programs, that belongs to RALLY computer code pack for the analysis of reliability systems

    International Nuclear Information System (INIS)

    Fernandes Filho, T.L.

    1982-11-01

    The RALLY computer code pack (RALLY pack) is a set of computer codes destinate to the reliability of complex systems, aiming to a risk analysis. Three of the six codes, are commented, presenting their purpose, input description, calculation methods and results obtained with each one of those computer codes. The computer codes are: TREBIL, to obtain the fault tree logical equivalent; CRESSEX, to obtain the minimal cut and the punctual values of the non-reliability and non-availability of the system; and STREUSL, for the dispersion calculation of those values around the media. In spite of the CRESSEX, in its version available at CNEN, uses a little long method to obtain the minimal cut in an HB-CNEN system, the three computer programs show good results, mainly the STREUSL, which permits the simulation of various components. (E.G.) [pt

  6. Application of reliability-centered maintenance to boiling water reactor emergency core cooling systems fault-tree analysis

    International Nuclear Information System (INIS)

    Choi, Y.A.; Feltus, M.A.

    1995-01-01

    Reliability-centered maintenance (RCM) methods are applied to boiling water reactor plant-specific emergency core cooling system probabilistic risk assessment (PRA) fault trees. The RCM is a technique that is system function-based, for improving a preventive maintenance (PM) program, which is applied on a component basis. Many PM programs are based on time-directed maintenance tasks, while RCM methods focus on component condition-directed maintenance tasks. Stroke time test data for motor-operated valves (MOVs) are used to address three aspects concerning RCM: (a) to determine if MOV stroke time testing was useful as a condition-directed PM task; (b) to determine and compare the plant-specific MOV failure data from a broad RCM philosophy time period compared with a PM period and, also, compared with generic industry MOV failure data; and (c) to determine the effects and impact of the plant-specific MOV failure data on core damage frequency (CDF) and system unavailabilities for these emergency systems. The MOV stroke time test data from four emergency core cooling systems [i.e., high-pressure coolant injection (HPCI), reactor core isolation cooling (RCIC), low-pressure core spray (LPCS), and residual heat removal/low-pressure coolant injection (RHR/LPCI)] were gathered from Philadelphia Electric Company's Peach Bottom Atomic Power Station Units 2 and 3 between 1980 and 1992. The analyses showed that MOV stroke time testing was not a predictor for eminent failure and should be considered as a go/no-go test. The failure data from the broad RCM philosophy showed an improvement compared with the PM-period failure rates in the emergency core cooling system MOVs. Also, the plant-specific MOV failure rates for both maintenance philosophies were shown to be lower than the generic industry estimates

  7. An artificial intelligence system for reliability studies

    International Nuclear Information System (INIS)

    Llory, M.; Ancelin, C.; Bannelier, M.; Bouhadana, H.; Bouissou, M.; Lucas, J.Y.; Magne, L.; Villate, N.

    1990-01-01

    The EDF (French Electricity Company) software developed for computer aided reliability studies is considered. Such software tools were applied in the study of the safety requirements of the Paluel nuclear power plant. The reliability models, based on IF-THEN type rules, and the generation of models by the expert system are described. The models are then processed applying algorithm structures [fr

  8. Downhole telemetry system reliability calculation and improvement

    Science.gov (United States)

    Trofimova, E. S.; Rubtsova, O. O.; Ishchenko, A. V.; Danilov, V. Yu.

    2017-09-01

    The article gives an estimation and a calculation of the reliability indexes for the downhole telemetry system downhole unit under severe operating conditions of high temperature environment. The reliability-growth methods are suggested. It is shown that the use of redundancy significantly extends mean time to failure even in high temperature environment.

  9. System Reliability Assessment of Offshore Pipelines

    NARCIS (Netherlands)

    Mustaffa, Z.

    2011-01-01

    The title of this thesis, System Reliability Assessment of Offshore Pipelines, portrays the application of probabilistic methods in assessing the reliability of these structures. The main intention of this thesis is to identify, apply and judge the suitability of the probabilistic methods in

  10. Reliable computer systems design and evaluatuion

    CERN Document Server

    Siewiorek, Daniel

    2014-01-01

    Enhance your hardware/software reliabilityEnhancement of system reliability has been a major concern of computer users and designers ¦ and this major revision of the 1982 classic meets users' continuing need for practical information on this pressing topic. Included are case studies of reliablesystems from manufacturers such as Tandem, Stratus, IBM, and Digital, as well as coverage of special systems such as the Galileo Orbiter fault protection system and AT&T telephone switching processors.

  11. B-52 stability augmentation system reliability

    Science.gov (United States)

    Bowling, T. C.; Key, L. W.

    1976-01-01

    The B-52 SAS (Stability Augmentation System) was developed and retrofitted to nearly 300 aircraft. It actively controls B-52 structural bending, provides improved yaw and pitch damping through sensors and electronic control channels, and puts complete reliance on hydraulic control power for rudder and elevators. The system has experienced over 300,000 flight hours and has exhibited service reliability comparable to the results of the reliability test program. Development experience points out numerous lessons with potential application in the mechanization and development of advanced technology control systems of high reliability.

  12. Reliability Results of NERSC Systems

    Energy Technology Data Exchange (ETDEWEB)

    Petascale Data Storage Institute (PDSI); Mokhtarani, Akbar; Mokhtarani, Akbar; Kramer, William; Hick, Jason

    2008-05-27

    In order to address the needs of future scientific applications for storing and accessing large amounts of data in an efficient way, one needs to understand the limitations of current technologies and how they may cause systeminstability or unavailability. A number of factors can impact system availability ranging from facility-wide power outage to a single point of failure such as network switches or global file systems. In addition, individual component failure in a system can degrade the performance of that system. This paper focuses on analyzing both of these factors and their impacts on the computational and storage systems at NERSC. Component failure data presented in this report primarily focuses on disk drive in on of the computational system and tape drive failure in HPSS. NERSC collected available component failure data and system-wide outages for its computational and storage systems over a six-year period and made them available to the HPC community through the Petascale Data Storage Institute.

  13. System Reliability of Timber Structures with Ductile Behaviour

    DEFF Research Database (Denmark)

    Kirkegaard, Poul Henning; Sørensen, John Dalsgaard; Čizmar, Dean

    2011-01-01

    . An evaluation method of the ductile behaviour is introduced. For different ductile behaviours, the system reliability is estimated based on Monte Carlo simulation. A correlation between the strength of the structural elements is introduced. The results indicate that the reliability of a structural timber system......The present paper considers the evaluation of timber structures with the focus on robustness due to connection ductility. The robustness analysis is based on the structural reliability framework applied to a simplified mechanical system. The structural timber system is depicted as a parallel system...... can be significantly increased due to the ductile behavior....

  14. Using three-dimension virtual reality main control room for integrated system validation and human reliability analysis

    International Nuclear Information System (INIS)

    Yang Chihwei; Cheng Tsungchieh

    2011-01-01

    This study proposes the performance assessment in three-dimension virtual reality (3D-VR) main control room (MCR). The assessment is conducted for integrated system validation (ISV) purposes, and also for human reliability analyses (HRA). This paper describes the latest developments in 3D-VR applications, designated for the familiarization with MCR, specially taking into account the ISV and HRA. The experiences in 3D-VR application, the benefits and advantages of use of VR in training and maintenances of MCR operators in the target NPP are equally presented in this paper. Results gathered from the performance measurement lead to hazard mitigation and reduces the risk of human error in the operation and maintenance of nuclear equipments. The latest developments in simulation techniques, including 3D presentation enhances the above mentioned benefits, brings the MCR simulators closer to reality. In the near future, this type of 3D solutions should be applied more and more often in the design of MCR simulators. The presented 3D-VR are related to the MCR in NPPs, but the concept of composition and navigation through the system's elements can be easily applied for the purpose of any type of technical equipment and shall contribute in a similar manner to hazard prevention. (author)

  15. Space Mission Human Reliability Analysis (HRA) Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The purpose of this project is to extend current ground-based Human Reliability Analysis (HRA) techniques to a long-duration, space-based tool to more effectively...

  16. Non-intrusive finite element reliability analysis methods

    OpenAIRE

    Papaioannou, Iason

    2014-01-01

    This thesis focuses on the modeling of uncertainties in structural systems and on strategies for the reliability assessment of structures analysed by finite element programs. New concepts are introduced for the numerical treatment of spatially varied uncertain quantities through the discretization of the relevant random fields as well as for robust and efficient finite element reliability analysis and updating of the reliability in light of new information. The methods have been implemented i...

  17. 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...

  18. A computer aided reliability and risk assessment system

    International Nuclear Information System (INIS)

    Leicht, R.; Hecke, R. van; Wingender, H.J.

    1991-01-01

    Activities in the fields of reliability and risk analysis have led to the development of particular software tools which are now combined in the PC-based integrated CARARA system. The options available in this system cover a wide range of reliability-oriented tasks, e.g. organising raw failure data in the component/event data bank FDB, performing statistical analysis of those data with the program FDA, managing the resulting parameters in the reliability data bank RDB, and performing fault tree analysis with the fault tree code FTL or evaluating the risk of toxic or radioactive material release with the STAR code. (orig.)

  19. Reliability analysis of a repairable k-out-of-n system with some components being suspended when the system is down

    International Nuclear Information System (INIS)

    Li Xiaohu; Zuo, Ming J.; Yam, Richard C.M.

    2006-01-01

    A k-out-of-n system with independent exponential components is investigated. It is assumed that some working components are suspended as soon as the system is down, repair starts immediately when a component fails and repair times are independent and exponentially distributed. Formulas for various reliability indices of the system including mean time between failures, mean working time in a failure-repair cycle, and mean down time in a failure-repair cycle are derived

  20. Reliability analysis of stiff versus flexible piping

    International Nuclear Information System (INIS)

    Lu, S.C.

    1985-01-01

    The overall objective of this research project is to develop a technical basis for flexible piping designs which will improve piping reliability and minimize the use of pipe supports, snubbers, and pipe whip restraints. The current study was conducted to establish the necessary groundwork based on the piping reliability analysis. A confirmatory piping reliability assessment indicated that removing rigid supports and snubbers tends to either improve or affect very little the piping reliability. The authors then investigated a couple of changes to be implemented in Regulatory Guide (RG) 1.61 and RG 1.122 aimed at more flexible piping design. They concluded that these changes substantially reduce calculated piping responses and allow piping redesigns with significant reduction in number of supports and snubbers without violating ASME code requirements. Furthermore, the more flexible piping redesigns are capable of exhibiting reliability levels equal to or higher than the original stiffer design. An investigation of the malfunction of pipe whip restraints confirmed that the malfunction introduced higher thermal stresses and tended to reduce the overall piping reliability. Finally, support and component reliabilities were evaluated based on available fragility data. Results indicated that the support reliability usually exhibits a moderate decrease as the piping flexibility increases. Most on-line pumps and valves showed an insignificant reduction in reliability for a more flexible piping design

  1. Reliability of power system with open access

    International Nuclear Information System (INIS)

    Ehsani, A.; Ranjbar, A. M.; Fotuhi Firuzabad, M.; Ehsani, M.

    2003-01-01

    Recently, in many countries, electric utility industry is undergoing considerable changes in regard to its structure and regulation. It can be clearly seen that the thrust towards privatization and deregulation or re regulation of the electric utility industry will introduce numerous reliability problems that will require new criteria and analytical tools that recognize the residual uncertainties in the new environment. In this paper, different risks and uncertainties in competitive electricity markets are briefly introduced; the approach of customers, operators, planners, generation bodies and network providers to the reliability of deregulated system is studied; the impact of dispersed generation on system reliability is evaluated; and finally, the reliability cost/reliability worth issues in the new competitive environment are considered

  2. Reliability assessment of restructured power systems using reliability network equivalent and pseudo-sequential simulation techniques

    International Nuclear Information System (INIS)

    Ding, Yi; Wang, Peng; Goel, Lalit; Billinton, Roy; Karki, Rajesh

    2007-01-01

    This paper presents a technique to evaluate reliability of a restructured power system with a bilateral market. The proposed technique is based on the combination of the reliability network equivalent and pseudo-sequential simulation approaches. The reliability network equivalent techniques have been implemented in the Monte Carlo simulation procedure to reduce the computational burden of the analysis. Pseudo-sequential simulation has been used to increase the computational efficiency of the non-sequential simulation method and to model the chronological aspects of market trading and system operation. Multi-state Markov models for generation and transmission systems are proposed and implemented in the simulation. A new load shedding scheme is proposed during generation inadequacy and network congestion to minimize the load curtailment. The IEEE reliability test system (RTS) is used to illustrate the technique. (author)

  3. Design for Reliability of Power Electronic Systems

    DEFF Research Database (Denmark)

    Yang, Yongheng; Wang, Huai; Sangwongwanich, Ariya

    2018-01-01

    Power density, efficiency, cost, and reliability are the major challenges when designing a power electronic system. Latest advancements in power semiconductor devices (e.g., silicon carbide devices) and topological innovations have vital contributions to power density and efficiency. Nevertheless.......e., mission profiles) is usually harsh, where the input power can change quickly and randomly, resulting in considerable temperature swings in the power electronics. This may induce failures to the power electronic systems. If remain untreated (i.e., ill-designed system without considering reliability......), the cost for maintenance will increase, thus affecting the reputation for the manufacturers and, more important, the cost of energy in renewables. Hence, it calls for highly reliable power electronic systems, where the reliability together with various common design parameters should be taken into account...

  4. Reliability of microtechnology interconnects, devices and systems

    CERN Document Server

    Liu, Johan; Sarkka, Jussi; Tegehall, Per-Erik; Andersson, Cristina

    2011-01-01

    This text discusses the reliability of microtechnology products from the bottom up, beginning with devices and extending to systems. It covers many topics, and it addresses specific failure modes in solder and conductive adhesives at great length.

  5. Recent Advances in System Reliability Signatures, Multi-state Systems and Statistical Inference

    CERN Document Server

    Frenkel, Ilia

    2012-01-01

    Recent Advances in System Reliability discusses developments in modern reliability theory such as signatures, multi-state systems and statistical inference. It describes the latest achievements in these fields, and covers the application of these achievements to reliability engineering practice. The chapters cover a wide range of new theoretical subjects and have been written by leading experts in reliability theory and its applications.  The topics include: concepts and different definitions of signatures (D-spectra),  their  properties and applications  to  reliability of coherent systems and network-type structures; Lz-transform of Markov stochastic process and its application to multi-state system reliability analysis; methods for cost-reliability and cost-availability analysis of multi-state systems; optimal replacement and protection strategy; and statistical inference. Recent Advances in System Reliability presents many examples to illustrate the theoretical results. Real world multi-state systems...

  6. Design for Reliability in Renewable Energy Systems

    DEFF Research Database (Denmark)

    Blaabjerg, Frede; Zhou, Dao; Sangwongwanich, Ariya

    2017-01-01

    Power electronics are widely used in renewable energy systems to achieve lower cost of energy, higher efficiency and high power density. At the same time, the high reliability of the power electronics products is demanded, in order to reduce the failure rates and ensure cost-effective operation...... of the renewable energy systems. This paper thus describes the basic concepts used in reliability engineering, and presents the status and future trends of Design for Reliability (DfR) in power electronics, which is currently undergoing a paradigm shift to a physics-of-failure approach. Two case studies of a 2 MW...

  7. Reliability and diagnostic of modular systems

    Directory of Open Access Journals (Sweden)

    J. Kohlas

    2014-01-01

    Full Text Available Reliability and diagnostic are in general two problems discussed separately. Yet the two problems are in fact closely related to each other. Here, this relation is considered in the simple case of modular systems. We show, how the computation of reliability and diagnostic can efficiently be done within the same Bayesian network induced by the modularity of the structure function of the system.

  8. Quality assurance procedures based on dosimetric, gamma analysis as a fast reliable tool for commissioning brachytherapy treatment planning systems

    Directory of Open Access Journals (Sweden)

    Zwierzchowski Grzegorz

    2017-11-01

    Full Text Available Fast and easily repeatable methods for commissioning procedures for brachytherapy (BT treatment planning systems (TPS are needed. Radiochromic film dosimetry with gamma analysis is widely used in external beam quality assurance (QA procedures and planar film dosimetry is also increasingly used for verification of the dose distribution in BT applications. Using the gamma analysis method for comparing calculated and measured dose data could be used for commissioning procedures of the newly developed TG-186 and MBDCA calculation algorithms. The aim of this study was dosimetric verification of the calculation algorithm used in TPS when the CT/MRI ring applicator is used.

  9. 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.

  10. Study on a System Reliability Calculation Method Using Failure Enumeration of Reliability Path

    International Nuclear Information System (INIS)

    Lee, Jang Il; Chun, Hwan Kyu; Jeong, Choong Min; Shin, Dong Jun; Suh, Myung Won; Park, Kee Jun

    2011-01-01

    Recently, systems such as aircraft, trains and ships have become larger more complex. Therefore, the reliability calculation of these systems is more difficult. This paper presents a reliability calculation algorithm for a complex system with a solution that is difficult to analyze. When the system has a very complex structure, it is very difficult to find an analytical solution. In this case, we can assess system reliability using the failure enumeration method of the reliability path. In this research, we represent the reliability block diagram by an adjacent matrix and define the reliability path. We can find any system status by the failure enumeration of the reliability path, and thus we can calculate any kind of system reliability through this process. This result can be applied to RCM (Reliability-Centered Maintenance) and reliability information-management systems, in which the system reliability is composed of the reliabilities of individual parts

  11. Human reliability analysis of dependent events

    International Nuclear Information System (INIS)

    Swain, A.D.; Guttmann, H.E.

    1977-01-01

    In the human reliability analysis in WASH-1400, the continuous variable of degree of interaction among human events was approximated by selecting four points on this continuum to represent the entire continuum. The four points selected were identified as zero coupling (i.e., zero dependence), complete coupling (i.e., complete dependence), and two intermediate points--loose coupling (a moderate level of dependence) and tight coupling (a high level of dependence). The paper expands the WASH-1400 treatment of common mode failure due to the interaction of human activities. Mathematical expressions for the above four levels of dependence are derived for parallel and series systems. The psychological meaning of each level of dependence is illustrated by examples, with probability tree diagrams to illustrate the use of conditional probabilities resulting from the interaction of human actions in nuclear power plant tasks

  12. A methodology for reliability analysis in health networks.

    Science.gov (United States)

    Spyrou, Stergiani; Bamidis, Panagiotis D; Maglaveras, Nicos; Pangalos, George; Pappas, Costas

    2008-05-01

    A reliability model for a health care domain based on requirement analysis at the early stage of design of regional health network (RHN) is introduced. RHNs are considered as systems supporting the services provided by health units, hospitals, and the regional authority. Reliability assessment in health care domain constitutes a field-of-quality assessment for RHN. A novel approach for predicting system reliability in the early stage of designing RHN systems is presented in this paper. The uppermost scope is to identify the critical processes of an RHN system prior to its implementation. In the methodology, Unified Modeling Language activity diagrams are used to identify megaprocesses at regional level and the customer behavior model graph (CBMG) to describe the states transitions of the processes. CBMG is annotated with: 1) the reliability of each component state and 2) the transition probabilities between states within the scope of the life cycle of the process. A stochastic reliability model (Markov model) is applied to predict the reliability of the business process as well as to identify the critical states and compare them with other processes to reveal the most critical ones. The ultimate benefit of the applied methodology is the design of more reliable components in an RHN system. The innovation of the approach of reliability modeling lies with the analysis of severity classes of failures and the application of stochastic modeling using discrete-time Markov chain in RHNs.

  13. Reliability demonstration of imaging surveillance systems

    International Nuclear Information System (INIS)

    Sheridan, T.F.; Henderson, J.T.; MacDiarmid, P.R.

    1979-01-01

    Security surveillance systems which employ closed circuit television are being deployed with increasing frequency for the protection of property and other valuable assets. A need exists to demonstrate the reliability of such systems before their installation to assure that the deployed systems will operate when needed with only the scheduled amount of maintenance and support costs. An approach to the reliability demonstration of imaging surveillance systems which employ closed circuit television is described. Failure definitions based on industry television standards and imaging alarm assessment criteria for surveillance systems are discussed. Test methods which allow 24 hour a day operation without the need for numerous test scenarios, test personnel and elaborate test facilities are presented. Existing reliability demonstration standards are shown to apply which obviate the need for elaborate statistical tests. The demonstration methods employed are shown to have applications in other types of imaging surveillance systems besides closed circuit television

  14. Food and Beverage Environment Analysis and Monitoring System (FoodBEAMS™): A Reliability Study in the School Food and Beverage Environment

    Science.gov (United States)

    Bullock, Sally Lawrence; Craypo, Lisa; Clark, Sarah E.; Barry, Jason; Samuels, Sarah E.

    2010-01-01

    States and school districts around the country are developing policies that set nutrition standards for competitive foods and beverages sold outside of the United States Department of Agriculture reimbursable school lunch program. However, few tools exist for monitoring the implementation of these new policies. The objective of this research was to develop a computerized assessment tool, the Food and Beverage Environment Analysis and Monitoring System (FoodBEAMS™), to collect data on the competitive school food environment and to test the inter-rater reliability of the tool among research and non-research professionals. FoodBEAMS was used to collect data in spring 2007, on the competitive foods and beverages sold in 21 California high schools. Adherence of the foods and beverages to California's competitive food and beverage nutrition policies for schools (Senate Bills 12 and 965) was determined using the data collected by both research and non-research professionals. The inter-rater reliability between the data collectors was assessed using the intraclass correlation coefficient (ICC). Researcher versus researcher and researcher versus non-researcher inter-rater reliability was high for both foods and beverages, with ICCs ranging from .972 to .987. The results of this study provide evidence that FoodBEAMS is a promising tool for assessing and monitoring adherence to nutrition standards for competitive foods sold on school campuses and can be used reliably by both research and non-research professionals. PMID:20630167

  15. TIGER reliability analysis in the DSN

    Science.gov (United States)

    Gunn, J. M.

    1982-01-01

    The TIGER algorithm, the inputs to the program and the output are described. TIGER is a computer program designed to simulate a system over a period of time to evaluate system reliability and availability. Results can be used in the Deep Space Network for initial spares provisioning and system evaluation.

  16. 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.

  17. Some aspects of the interaction between systems- and structural reliability

    International Nuclear Information System (INIS)

    Schueller, G.K.; Schmitt, W.

    1979-01-01

    The purpose of this paper is to study the interaction between systems- and structural reliability analysis with reference to the design of structural components of LWR. Presently the evaluation of systems reliability is carried out apart from structural reliability analysis. Moreover, two basically different methodologies are used for analysis. While in systems analysis the simplified binary approach is still generally accepted, in structural reliability one has to resort to more sophisticated procedures to obtain realistic results. The interactive effect may be illustrated as follows: For example, the integrity of the primary circuit interacts with the integrity of the containment structure. This means that the probability of occurrence of the pipe rupture which may cause a LOCA and consequently leads to a build-up of temperature and pressure within the containment affects directly its structural reliability. The piping system, particularly the primary piping, in turn interacts with the protective system, which is part of the safety system. This piping structure is also subjected to various operational loading conditions. In a numerical example dealing with leakage probabilities of pipes it is shown how methods of structural reliability may be used to gain more insight in the estimation of failure rates of system components. (orig.)

  18. Advanced Reconnaissance System Component Reliability Study

    Science.gov (United States)

    1956-07-31

    or chemical interaction of the air atoms and molecules.on the vehicle skin or lens and window materials. The quantity of molecules present is very low...I Mill -• •ri... ": :’s t:.... 111 . . . orIII. i...1 MINI . • ; . . .1...!.... : . •..1 • . , , BIM El MIMIIMO= .. insma’ • • . wart...Reliability were discussed. "Some Reliability Aspects of Systems Design", Moskowitz, Fred and * Lean , John’, RADC Technical Note 55-4 "Reliability is

  19. Human reliability guidance - How to increase the synergies between human reliability, human factors, and system design and engineering. Phase 1: The Nordic Point of View - A user needs analysis

    International Nuclear Information System (INIS)

    Oxstrand, J.; Boring, R.L.

    2010-12-01

    The main goal of this Nordic Nuclear Safety Research (NKS) council project is to produce guidance for how to use human reliability analysis (HRA) to strengthen overall safety. This project is intended to work across (and hopefully diminish) the borders that exist between human reliability analysis (HRA) and human-system interaction, human performance, human factors, and probabilistic risk assessment at Nordic nuclear power plants. This project consists of two major phases, where the initial phase (phase 1) is a study of current practices in the Nordic region, which is presented in this report. Even though the project covers the synergies between HRA and all other relevant fields, the main focus for the phase is to bridge HRA and design. Interviews with 26 Swedish and Finnish plant experts are summarized the present report, and 10 principles to improve the utilization of HRA at plants are presented. A second study, which is not documented in this preliminary report, will chronicle insights into how the US nuclear industry works with HRA. To gain this knowledge the author will conduct interviews with the US regulator, research laboratories, and utilities. (Author)

  20. Systems analysis programs for Hands-on integrated reliability evaluations (SAPHIRE) Version 5.0: Verification and validation (V ampersand V) manual. Volume 9

    International Nuclear Information System (INIS)

    Jones, J.L.; Calley, M.B.; Capps, E.L.; Zeigler, S.L.; Galyean, W.J.; Novack, S.D.; Smith, C.L.; Wolfram, L.M.

    1995-03-01

    A verification and validation (V ampersand V) process has been performed for the System Analysis Programs for Hands-on Integrated Reliability Evaluation (SAPHIRE) Version 5.0. SAPHIRE is a set of four computer programs that NRC developed for performing probabilistic risk assessments. They allow an analyst to perform many of the functions necessary to create, quantify, and evaluate the risk associated with a facility or process being analyzed. The programs are Integrated Reliability and Risk Analysis System (IRRAS) System Analysis and Risk Assessment (SARA), Models And Results Database (MAR-D), and Fault tree, Event tree, and Piping and instrumentation diagram (FEP) graphical editor. Intent of this program is to perform a V ampersand V of successive versions of SAPHIRE. Previous efforts have been the V ampersand V of SAPHIRE Version 4.0. The SAPHIRE 5.0 V ampersand V plan is based on the SAPHIRE 4.0 V ampersand V plan with revisions to incorporate lessons learned from the previous effort. Also, the SAPHIRE 5.0 vital and nonvital test procedures are based on the test procedures from SAPHIRE 4.0 with revisions to include the new SAPHIRE 5.0 features as well as to incorporate lessons learned from the previous effort. Most results from the testing were acceptable; however, some discrepancies between expected code operation and actual code operation were identified. Modifications made to SAPHIRE are identified

  1. System Reliability for LED-Based Products

    Energy Technology Data Exchange (ETDEWEB)

    Davis, J Lynn; Mills, Karmann; Lamvik, Michael; Yaga, Robert; Shepherd, Sarah D; Bittle, James; Baldasaro, Nick; Solano, Eric; Bobashev, Georgiy; Johnson, Cortina; Evans, Amy

    2014-04-07

    Results from accelerated life tests (ALT) on mass-produced commercially available 6” downlights are reported along with results from commercial LEDs. The luminaires capture many of the design features found in modern luminaires. In general, a systems perspective is required to understand the reliability of these devices since LED failure is rare. In contrast, components such as drivers, lenses, and reflector are more likely to impact luminaire reliability than LEDs.

  2. Reliability Driven Space Logistics Demand Analysis

    Science.gov (United States)

    Knezevic, J.

    1995-01-01

    Accurate selection of the quantity of logistic support resources has a strong influence on mission success, system availability and the cost of ownership. At the same time the accurate prediction of these resources depends on the accurate prediction of the reliability measures of the items involved. This paper presents a method for the advanced and accurate calculation of the reliability measures of complex space systems which are the basis for the determination of the demands for logistics resources needed during the operational life or mission of space systems. The applicability of the method presented is demonstrated through several examples.

  3. RELIABILITY ANALYSIS OF BENDING ELIABILITY ANALYSIS OF ...

    African Journals Online (AJOL)

    eobe

    We note here that the general reliability index is defined with the assumption that the sole available information ... the normalized space. But it is obvious that symmetry-disturbing restrictions are satisfied ... Φ= (4). By a Taylor power series expansion of Equation (3) in correspondence with the checking point vector Y* and.

  4. Human Reliability Analysis for Small Modular Reactors

    Energy Technology Data Exchange (ETDEWEB)

    Ronald L. Boring; David I. Gertman

    2012-06-01

    Because no human reliability analysis (HRA) method was specifically developed for small modular reactors (SMRs), the application of any current HRA method to SMRs represents tradeoffs. A first- generation HRA method like THERP provides clearly defined activity types, but these activity types do not map to the human-system interface or concept of operations confronting SMR operators. A second- generation HRA method like ATHEANA is flexible enough to be used for SMR applications, but there is currently insufficient guidance for the analyst, requiring considerably more first-of-a-kind analyses and extensive SMR expertise in order to complete a quality HRA. Although no current HRA method is optimized to SMRs, it is possible to use existing HRA methods to identify errors, incorporate them as human failure events in the probabilistic risk assessment (PRA), and quantify them. In this paper, we provided preliminary guidance to assist the human reliability analyst and reviewer in understanding how to apply current HRA methods to the domain of SMRs. While it is possible to perform a satisfactory HRA using existing HRA methods, ultimately it is desirable to formally incorporate SMR considerations into the methods. This may require the development of new HRA methods. More practicably, existing methods need to be adapted to incorporate SMRs. Such adaptations may take the form of guidance on the complex mapping between conventional light water reactors and small modular reactors. While many behaviors and activities are shared between current plants and SMRs, the methods must adapt if they are to perform a valid and accurate analysis of plant personnel performance in SMRs.

  5. Software engineering practices for control system reliability

    International Nuclear Information System (INIS)

    S. K. Schaffner; K. S White

    1999-01-01

    This paper will discuss software engineering practices used to improve Control System reliability. The authors begin with a brief discussion of the Software Engineering Institute's Capability Maturity Model (CMM) which is a framework for evaluating and improving key practices used to enhance software development and maintenance capabilities. The software engineering processes developed and used by the Controls Group at the Thomas Jefferson National Accelerator Facility (Jefferson Lab), using the Experimental Physics and Industrial Control System (EPICS) for accelerator control, are described. Examples are given of how their procedures have been used to minimized control system downtime and improve reliability. While their examples are primarily drawn from their experience with EPICS, these practices are equally applicable to any control system. Specific issues addressed include resource allocation, developing reliable software lifecycle processes and risk management

  6. Heroic Reliability Improvement in Manned Space Systems

    Science.gov (United States)

    Jones, Harry W.

    2017-01-01

    System reliability can be significantly improved by a strong continued effort to identify and remove all the causes of actual failures. Newly designed systems often have unexpected high failure rates which can be reduced by successive design improvements until the final operational system has an acceptable failure rate. There are many causes of failures and many ways to remove them. New systems may have poor specifications, design errors, or mistaken operations concepts. Correcting unexpected problems as they occur can produce large early gains in reliability. Improved technology in materials, components, and design approaches can increase reliability. The reliability growth is achieved by repeatedly operating the system until it fails, identifying the failure cause, and fixing the problem. The failure rate reduction that can be obtained depends on the number and the failure rates of the correctable failures. Under the strong assumption that the failure causes can be removed, the decline in overall failure rate can be predicted. If a failure occurs at the rate of lambda per unit time, the expected time before the failure occurs and can be corrected is 1/lambda, the Mean Time Before Failure (MTBF). Finding and fixing a less frequent failure with the rate of lambda/2 per unit time requires twice as long, time of 1/(2 lambda). Cutting the failure rate in half requires doubling the test and redesign time and finding and eliminating the failure causes.Reducing the failure rate significantly requires a heroic reliability improvement effort.

  7. Reliability Analysis of the new Link between the Beam Interlock System and the LHC Beam Dumping System Zuverlässigkeitsanalyse der neuen Verbindung zwischen dem Beam Interlock System und dem LHC Beam Dumping System

    CERN Document Server

    Vatansever, Volkan

    The nominal stored energy in each LHC beam is 360 MJ, surpassing the beam energy of other accelerators by orders of magnitude. This energy threatens to damage accelerator components in case of uncontrolled beam losses To avoid damage of accelerator equipment due to impacting beam, the controlled removal of the LHC beams from the collider rings towards the dump block must be guaranteed at all times. Therefore, the LHC Beam Dumping System was built according to high reliability standards. To further reduce the risk of incapability to dump the beams in case of correlated failures in the redundant system, a new direct link from the LHC Beam Interlock System to the Re-triggering Lines of the LHC Beam Dumping System will be implemented for the startup with beam in 2015. This link represents a diverse redundancy to the current implementation, which should neither significantly increase the risk for so-called Asynchronous Beam Dumps nor compromise machine availability. Therefore, a reliability analysis down to the co...

  8. Analysis of sodium valve reliability data at CREDO

    International Nuclear Information System (INIS)

    Bott, T.F.; Haas, P.M.

    1979-01-01

    The Centralized Reliability Data Organization (CREDO) has been established at Oak Ridge National Laboratory (ORNL) by the Department of Energy to provide a centralized source of data for reliability/maintainabilty analysis of advanced reactor systems. The current schedule calls for develoment of the data system at a moderate pace, with the first major distribution of data in late FY-1980. Continuous long-term collection of engineering, operating, and event data has been initiated at EBR-II and FFTF

  9. Reliability demonstration test planning using bayesian analysis

    International Nuclear Information System (INIS)

    Chandran, Senthil Kumar; Arul, John A.

    2003-01-01

    In Nuclear Power Plants, the reliability of all the safety systems is very critical from the safety viewpoint and it is very essential that the required reliability requirements be met while satisfying the design constraints. From practical experience, it is found that the reliability of complex systems such as Safety Rod Drive Mechanism is of the order of 10 -4 with an uncertainty factor of 10. To demonstrate the reliability of such systems is prohibitive in terms of cost and time as the number of tests needed is very large. The purpose of this paper is to develop a Bayesian reliability demonstrating testing procedure for exponentially distributed failure times with gamma prior distribution on the failure rate which can be easily and effectively used to demonstrate component/subsystem/system reliability conformance to stated requirements. The important questions addressed in this paper are: With zero failures, how long one should perform the tests and how many components are required to conclude with a given degree of confidence, that the component under test, meets the reliability requirement. The procedure is explained with an example. This procedure can also be extended to demonstrate with more number of failures. The approach presented is applicable for deriving test plans for demonstrating component failure rates of nuclear power plants, as the failure data for similar components are becoming available in existing plants elsewhere. The advantages of this procedure are the criterion upon which the procedure is based is simple and pertinent, the fitting of the prior distribution is an integral part of the procedure and is based on the use of information regarding two percentiles of this distribution and finally, the procedure is straightforward and easy to apply in practice. (author)

  10. Reliability modelling and simulation of switched linear system ...

    African Journals Online (AJOL)

    Thus, constructing a subsystem Markov model and matching its parameters with the specified safety factors provides the basis for the entire system analysis. For the system simulation, temporal databases and predictive control algorithm are designed. The simulation results are analyzed to assess the reliability of the system ...

  11. Influence Of Inspection Intervals On Mechanical System Reliability

    International Nuclear Information System (INIS)

    Zilberman, B.

    1998-01-01

    In this paper a methodology of reliability analysis of mechanical systems with latent failures is described. Reliability analysis of such systems must include appropriate usage of check intervals for latent failure detection. The methodology suggests, that based on system logic the analyst decides at the beginning if a system can fail actively or latently and propagates this approach through all system levels. All inspections are assumed to be perfect (all failures are detected and repaired and no new failures are introduced as a result of the maintenance). Additional assumptions are that mission time is much smaller, than check intervals and all components have constant failure rates. Analytical expressions for reliability calculates are provided, based on fault tree and Markov modeling techniques (for two and three redundant systems with inspection intervals). The proposed methodology yields more accurate results than are obtained by not using check intervals or using half check interval times. The conventional analysis assuming that at the beginning of each mission system is as new, give an optimistic prediction of system reliability. Some examples of reliability calculations of mechanical systems with latent failures and establishing optimum check intervals are provided

  12. Reliability Analysis of a Steel Frame

    Directory of Open Access Journals (Sweden)

    M. Sýkora

    2002-01-01

    Full Text Available A steel frame with haunches is designed according to Eurocodes. The frame is exposed to self-weight, snow, and wind actions. Lateral-torsional buckling appears to represent the most critical criterion, which is considered as a basis for the limit state function. In the reliability analysis, the probabilistic models proposed by the Joint Committee for Structural Safety (JCSS are used for basic variables. The uncertainty model coefficients take into account the inaccuracy of the resistance model for the haunched girder and the inaccuracy of the action effect model. The time invariant reliability analysis is based on Turkstra's rule for combinations of snow and wind actions. The time variant analysis describes snow and wind actions by jump processes with intermittencies. Assuming a 50-year lifetime, the obtained values of the reliability index b vary within the range from 3.95 up to 5.56. The cross-profile IPE 330 designed according to Eurocodes seems to be adequate. It appears that the time invariant reliability analysis based on Turkstra's rule provides considerably lower values of b than those obtained by the time variant analysis.

  13. Analysis of operating reliability of WWER-1000 unit

    International Nuclear Information System (INIS)

    Bortlik, J.

    1985-01-01

    The nuclear power unit was divided into 33 technological units. Input data for reliability analysis were surveys of operating results obtained from the IAEA information system and certain indexes of the reliability of technological equipment determined using the Bayes formula. The missing reliability data for technological equipment were used from the basic variant. The fault tree of the WWER-1000 unit was determined for the peak event defined as the impossibility of reaching 100%, 75% and 50% of rated power. The period was observed of the nuclear power plant operation with reduced output owing to defect and the respective time needed for a repair of the equipment. The calculation of the availability of the WWER-1000 unit was made for different variant situations. Certain indexes of the operating reliability of the WWER-1000 unit which are the result of a detailed reliability analysis are tabulated for selected variants. (E.S.)

  14. Safety and reliability assessment by using dynamic reliability analysis method

    International Nuclear Information System (INIS)

    Lee, Sook Hyung; Oh, Se Ki

    1997-01-01

    DYLAM and its related applications are reviewed in detail and found to have many favorable characteristics. Concerning human factor analysis, the study demonstrates that DYLAM methodology represents and appropriate tool to study man-machine behavior provided that DYLAM is used to model machine behavior and an appropriate operator interface human factor model is included. A hybrid model which is a synthesis of the DYLAM model, a system thermodynamic simulation model and a neutral network predicative model, is implemented and used to analyze dynamically the CANDU pressurizer system

  15. Power plant productivity and reliability information system

    Energy Technology Data Exchange (ETDEWEB)

    Pazos, R.; Lizarraga, E.

    1988-04-01

    This article describes an information system for handling equipment failure information of fossil fuel plants. This system produces 33 different reports, which contain failure statistics, plant availability, unavailability classified by cause, plant reliability indices, and maintenance productivity indices. Some of the innovations introduced by this system are: (1) event partition into any number of subevents for accurate description of event evolution, (2) separation of equipment and event cause for easy reporting, and (3) failure-mode information for better event description.

  16. Sustainable, Reliable Mission-Systems Architecture

    Science.gov (United States)

    O'Neil, Graham; Orr, James K.; Watson, Steve

    2007-01-01

    A mission-systems architecture, based on a highly modular infrastructure utilizing: open-standards hardware and software interfaces as the enabling technology is essential for affordable and sustainable space exploration programs. This mission-systems architecture requires (a) robust communication between heterogeneous system, (b) high reliability, (c) minimal mission-to-mission reconfiguration, (d) affordable development, system integration, and verification of systems, and (e) minimal sustaining engineering. This paper proposes such an architecture. Lessons learned from the Space Shuttle program and Earthbound complex engineered system are applied to define the model. Technology projections reaching out 5 years are mde to refine model details.

  17. Reliability analysis of prestressed concrete containment structures

    International Nuclear Information System (INIS)

    Jiang, J.; Zhao, Y.; Sun, J.

    1993-01-01

    The reliability analysis of prestressed concrete containment structures subjected to combinations of static and dynamic loads with consideration of uncertainties of structural and load parameters is presented. Limit state probabilities for given parameters are calculated using the procedure developed at BNL, while that with consideration of parameter uncertainties are calculated by a fast integration for time variant structural reliability. The limit state surface of the prestressed concrete containment is constructed directly incorporating the prestress. The sensitivities of the Choleskey decomposition matrix and the natural vibration character are calculated by simplified procedures. (author)

  18. Reliability Issues in Distributed Operating Systems

    NARCIS (Netherlands)

    Tanenbaum, A.S.; van Renesse, R.

    1987-01-01

    The authors examine the various kinds of distributed systems and discuss some of the reliability issues involved. They first concentrate on the causes of unreliability, illustrating these with some general solutions and examples. Among the issues treated are interprocess communication, machine

  19. Reliability achievement in high technology space systems

    Science.gov (United States)

    Lindstrom, D. L.

    1981-01-01

    The production of failure-free hardware is discussed. The elements required to achieve such hardware are: technical expertise to design, analyze, and fully understand the design; use of high reliability parts and materials control in the manufacturing process; and testing to understand the system and weed out defects. The durability of the Hughes family of satellites is highlighted.

  20. System-Reliability Cumulative-Binomial Program

    Science.gov (United States)

    Scheuer, Ernest M.; Bowerman, Paul N.

    1989-01-01

    Cumulative-binomial computer program, NEWTONP, one of set of three programs, calculates cumulative binomial probability distributions for arbitrary inputs. NEWTONP, CUMBIN (NPO-17555), and CROSSER (NPO-17557), used independently of one another. Program finds probability required to yield given system reliability. Used by statisticians and users of statistical procedures, test planners, designers, and numerical analysts. Program written in C.

  1. A Reliability Assessment Method for the VHTR Safety Systems

    International Nuclear Information System (INIS)

    Lee, Hyung Sok; Jae, Moo Sung; Kim, Yong Wan

    2011-01-01

    The Passive safety system by very high temperature reactor which has attracted worldwide attention in the last century is the reliability safety system introduced for the improvement in the safety of the next generation nuclear power plant design. The Passive system functionality does not rely on an external source of energy, but on an intelligent use of the natural phenomena, such as gravity, conduction and radiation, which are always present. Because of these features, it is difficult to evaluate the passive safety on the risk analysis methodology having considered the existing active system failure. Therefore new reliability methodology has to be considered. In this study, the preliminary evaluation and conceptualization are tried, applying the concept of the load and capacity from the reliability physics model, designing the new passive system analysis methodology, and the trial applying to paper plant.

  2. Reliability modeling of an engineered barrier system

    International Nuclear Information System (INIS)

    Ananda, M.M.A.; Singh, A.K.; Flueck, J.A.

    1993-01-01

    The Weibull distribution is widely used in reliability literature as a distribution of time to failure, as it allows for both increasing failure rate (IFR) and decreasing failure rate (DFR) models. It has also been used to develop models for an engineered barrier system (EBS), which is known to be one of the key components in a deep geological repository for high level radioactive waste (HLW). The EBS failure time can more realistically be modelled by an IFR distribution, since the failure rate for the EBS is not expected to decrease with time. In this paper, we use an IFR distribution to develop a reliability model for the EBS

  3. Systems Analysis Programs for Hands-on Integrated Reliability Evaluations (SAPHIRE), Version 5.0: Models and Results Database (MAR-D) reference manual. Volume 8

    International Nuclear Information System (INIS)

    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. The primary function of MAR-D is to create a data repository for completed PRAs and Individual Plant Examinations (IPEs) by providing input, conversion, and output capabilities for data used by IRRAS, SARA, SETS, and FRANTIC software. As probabilistic risk assessments and individual plant examinations are submitted to the NRC for review, MAR-D can be used to convert the models and results from the study for use with IRRAS and SARA. Then, these data can be easily accessed by future studies and will be in a form that will enhance the analysis process. This reference manual provides an overview of the functions available within MAR-D and step-by-step operating instructions

  4. Analysis of the reliability of the local effect model for the use in carbon ion treatment planning systems.

    Science.gov (United States)

    Russo, G; Attili, A; Bourhaleb, F; Marchetto, F; Peroni, C; Schmitt, E; Bertrand, D

    2011-02-01

    In radiotherapy with carbon ions, biological effects of treatments have to be predicted. For this purpose, one of the most used models is the local effect model (LEM) developed at the Gesellschaft für Schwerionenforschung (GSI), Germany. At the Istituto Nazionale di Fisica Nucleare, Italy, the reliability of the last published version of LEM (LEM III) in reproducing radiobiological data has been checked under both monoenergetic and spread-out Bragg peak (SOBP) carbon-ion irradiation. The reproduction of the monoenergetic measurements with the LEM was rather successful for some cell lines, while it failed for the less-radioresistant ones. The SOBP experimental trend was predicted by the LEM, but a large shift between model curves and measured points was observed.

  5. 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

  6. Reliability systems for implantable cardiac defibrillator batteries

    Science.gov (United States)

    Takeuchi, Esther S.

    The reliability of the power sources used in implantable cardiac defibrillators is critical due to the life-saving nature of the device. Achieving a high reliability power source depends on several systems functioning together. Appropriate cell design is the first step in assuring a reliable product. Qualification of critical components and of the cells using those components is done prior to their designation as implantable grade. Product consistency is assured by control of manufacturing practices and verified by sampling plans using both accelerated and real-time testing. Results to date show that lithium/silver vanadium oxide cells used for implantable cardiac defibrillators have a calculated maximum random failure rate of 0.005% per test month.

  7. Reliability Standards of Complex Engineering Systems

    Science.gov (United States)

    Galperin, E. M.; Zayko, V. A.; Gorshkalev, P. A.

    2017-11-01

    Production and manufacture play an important role in today’s modern society. Industrial production is nowadays characterized by increased and complex communications between its parts. The problem of preventing accidents in a large industrial enterprise becomes especially relevant. In these circumstances, the reliability of enterprise functioning is of particular importance. Potential damage caused by an accident at such enterprise may lead to substantial material losses and, in some cases, can even cause a loss of human lives. That is why industrial enterprise functioning reliability is immensely important. In terms of their reliability, industrial facilities (objects) are divided into simple and complex. Simple objects are characterized by only two conditions: operable and non-operable. A complex object exists in more than two conditions. The main characteristic here is the stability of its operation. This paper develops the reliability indicator combining the set theory methodology and a state space method. Both are widely used to analyze dynamically developing probability processes. The research also introduces a set of reliability indicators for complex technical systems.

  8. Improvement on reliability of control system in power plant

    International Nuclear Information System (INIS)

    Taguchi, S.; Mizumoto, T.; Hirose, Y.; Kashiwai, J.; Takami, I.; Shono, M.; Roji, Y.; Kizaki, S.

    1985-01-01

    Studies made of Japanese PWR operating experiences have revealed that failures in the control system are the primary causes of unscheduled shutdowns. An attempt has, therefore, been made to improve the reliability of the control system in order to raise the plant reliability. The following are the procedures applied to solve the issue; study of operating experiences, fault tree analysis and failure mode and effects analysis. Improvement measures are developed for the control system whose failure threatens to cause the plant trip during the plant life. These systems are the main feedwater control system, rod control system, pressurizer control system and main steam control system in the primary control system. As a result, the plant unavailability is expected to be reduced significantly by applying the improvements. The improvements are applied to the plants under construction and the operating plants in co-operation with utilities and vendors. (author)

  9. [Analysis of validity and reliability of three radiographic classification systems for preoperative assessment of bone stock loss in revision total hip arthroplasty].

    Science.gov (United States)

    Käfer, W; Fraitzl, C R; Kinkel, S; Puhl, W; Kessler, S

    2004-01-01

    It was the purpose of this prospective study to analyze validity and reliability of three different radiographic classification systems, which are used to assess bone stock loss prior to revision total hip arthroplasty. Investigation was performed using the classification systems according to 1) Paprosky et al., 2) Hungerford et al., and 3) the German Society of Orthopaedics and Traumatology (DGOT). Twenty-eight consecutive patients with diagnosis of aseptic failure of total hip arthroplasty were enrolled in the study. Interrater agreement was analyzed by evaluating the classifications preoperatively by three investigators with different level of clinical experience using a blinded observer technique. Validity was analyzed by comparison of preoperative radiographic findings (n = 3) and an intraoperative control by visualization and palpation (n = 1). Spearman coefficient of correlation (r(s)) was used to establish levels of agreement among multiple ordinal variables. Interrater reliability testing using paired comparison between the three investigators revealed non-homogeneous coefficients of correlation (r(s): Paprosky femur: 0.45 - 0.67, acetabulum: 0.38 - 0.63; Hungerford: 0.46 - 0.66; DGOT femur: 0.38 - 0.59, acetabulum: 0.42 - 0.76). Paired analysis of correlation between preoperative and intraoperative findings again showed non-homogeneous coefficients of correlation (r(s): Paprosky femur: 0.59 - 0.68, acetabulum: 0.39 - 0.70; Hungerford: 0.39 - 0.74; DGOT femur: 0.44 - 0.60, acetabulum: 0.36 - 0.76). In general, defects were grossly underestimated preoperatively. The level of experience did not influence the validity of measurements. Our results indicate that these classifications do not provide valid and reliable assessment of femoral and acetabular bone stock loss prior to revision total hip arthroplasty.

  10. Reliability analysis of PLC safety equipment

    Energy Technology Data Exchange (ETDEWEB)

    Yu, J.; Kim, J. Y. [Chungnam Nat. Univ., Daejeon (Korea, Republic of)

    2006-06-15

    FMEA analysis for Nuclear Safety Grade PLC, failure rate prediction for nuclear safety grade PLC, sensitivity analysis for components failure rate of nuclear safety grade PLC, unavailability analysis support for nuclear safety system.

  11. Reliability analysis of PLC safety equipment

    International Nuclear Information System (INIS)

    Yu, J.; Kim, J. Y.

    2006-06-01

    FMEA analysis for Nuclear Safety Grade PLC, failure rate prediction for nuclear safety grade PLC, sensitivity analysis for components failure rate of nuclear safety grade PLC, unavailability analysis support for nuclear safety system

  12. 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

  13. 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

  14. Bridging Resilience Engineering and Human Reliability Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Ronald L. Boring

    2010-06-01

    There has been strong interest in the new and emerging field called resilience engineering. This field has been quick to align itself with many existing safety disciplines, but it has also distanced itself from the field of human reliability analysis. To date, the discussion has been somewhat one-sided, with much discussion about the new insights afforded by resilience engineering. This paper presents an attempt to address resilience engineering from the perspective of human reliability analysis (HRA). It is argued that HRA shares much in common with resilience engineering and that, in fact, it can help strengthen nascent ideas in resilience engineering. This paper seeks to clarify and ultimately refute the arguments that have served to divide HRA and resilience engineering.

  15. The Component And System Reliability Analysis Of Multipurpose Reactor G.A. Subway's Based On The Failure Rate Curve

    International Nuclear Information System (INIS)

    Sriyono; Ismu Wahyono, Puradwi; Mulyanto, Dwijo; Kusmono, Siamet

    2001-01-01

    The main component of Multipurpose G.A.Siwabessy had been analyzed by its failure rate curve. The main component ha'..e been analyzed namely, the pump of ''Fuel Storage Pool Purification System'' (AK-AP), ''Primary Cooling System'' (JE01-AP), ''Primary Pool Purification System'' (KBE01-AP), ''Warm Layer System'' (KBE02-AP), ''Cooling Tower'' (PA/D-AH), ''Secondary Cooling System'', and Diesel (BRV). The Failure Rate Curve is made by component database that was taken from 'log book' operation of RSG GAS. The total operation of that curve is 2500 hours. From that curve it concluded that the failure rate of components form of bathtub curve. The maintenance processing causes the curve anomaly

  16. Reliability Analysis for Safety Grade PLC

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Kyung Chul; Hwang, Sung Jae; Jung, Tae Hyok; Kim, Tae Hee; Song, Seung Whan [POSCO ICT Co., Seoul (Korea, Republic of)

    2010-10-15

    In this paper, describe reliability analysis for digital safety grade PLC which developed with the aim to use the operating nuclear power plants and new plants by POSCO ICT co., POSAFE-Q consist of the Sub Rack, power modules, processor modules, communication modules, digital input / output module (DI / DO), analog input / output modules (AI / AO), pulse counter module, TC (Thermocouple), RTD (Resistance Temperature Detector), Local Repeater

  17. System ergonomics as an approach to improve human reliability

    International Nuclear Information System (INIS)

    Bubb, H.

    1988-01-01

    The application of system technics on ergonomical problems is called system ergonomics. This enables improvements of human reliability by design measures. The precondition for this is the knowledge of how information processing is performed by man and machine. By a separate consideration of sensory processing, cognitive processing, and motory processing it is possible to have a more exact idea of the system element 'man'. The system element 'machine' is well described by differential equations which allow an ergonomical assessment of the manouverability. The knowledge of information processing of man and machine enables a task analysis. This makes appear on one hand the human boundaries depending on the different properties of the task and on the other hand suitable ergonomical solution proposals which improve the reliability of the total system. It is a disadvantage, however, that the change of human reliability by such measures may not be quoted numerically at the moment. (orig.)

  18. Small nuclear power reactor emergency electric power supply system reliability comparative analysis; Analise da confiabilidade do sistema de suprimento de energia eletrica de emergencia de um reator nuclear de pequeno porte

    Energy Technology Data Exchange (ETDEWEB)

    Bonfietti, Gerson

    2003-07-01

    This work presents an analysis of the reliability of the emergency power supply system, of a small size nuclear power reactor. Three different configurations are investigated and their reliability analyzed. The fault tree method is used as the main tool of analysis. The work includes a bibliographic review of emergency diesel generator reliability and a discussion of the design requirements applicable to emergency electrical systems. The influence of common cause failure influences is considered using the beta factor model. The operator action is considered using human failure probabilities. A parametric analysis shows the strong dependence between the reactor safety and the loss of offsite electric power supply. It is also shown that common cause failures can be a major contributor to the system reliability. (author)

  19. Network reliability analysis based on percolation theory

    International Nuclear Information System (INIS)

    Li, Daqing; Zhang, Qiong; Zio, Enrico; Havlin, Shlomo; Kang, Rui

    2015-01-01

    In this paper, we propose a new way of looking at the reliability of a network using percolation theory. In this new view, a network failure can be regarded as a percolation process and the critical threshold of percolation can be used as network failure criterion linked to the operational settings under control. To demonstrate our approach, we consider both random network models and real networks with different nodes and/or edges lifetime distributions. We study numerically and theoretically the network reliability and find that the network reliability can be solved as a voting system with threshold given by percolation theory. Then we find that the average lifetime of random network increases linearly with the average lifetime of its nodes with uniform life distributions. Furthermore, the average lifetime of the network becomes saturated when system size is increased. Finally, we demonstrate our method on the transmission network system of IEEE 14 bus. - Highlights: • Based on percolation theory, we address questions of practical interest such as “how many failed nodes/edges will break down the whole network?” • The percolation threshold naturally gives a network failure criterion. • The approach based on percolation theory is suited for calculations of large-scale networks

  20. 76 FR 42534 - Mandatory Reliability Standards for Interconnection Reliability Operating Limits; System...

    Science.gov (United States)

    2011-07-19

    ... Reliability Operating Limits; System Restoration Reliability Standards AGENCY: Federal Energy Regulatory... data necessary to analyze and monitor Interconnection Reliability Operating Limits (IROL) within its... Interconnection Reliability Operating Limits, Order No. 748, 134 FERC ] 61,213 (2011). \\2\\ The term ``Wide-Area...

  1. Reliability Engineering

    International Nuclear Information System (INIS)

    Lee, Sang Yong

    1992-07-01

    This book is about reliability engineering, which describes definition and importance of reliability, development of reliability engineering, failure rate and failure probability density function about types of it, CFR and index distribution, IFR and normal distribution and Weibull distribution, maintainability and movability, reliability test and reliability assumption in index distribution type, normal distribution type and Weibull distribution type, reliability sampling test, reliability of system, design of reliability and functionality failure analysis by FTA.

  2. DATMAN: A reliability data analysis program using Bayesian updating

    International Nuclear Information System (INIS)

    Becker, M.; Feltus, M.A.

    1996-01-01

    Preventive maintenance (PM) techniques focus on the prevention of failures, in particular, system components that are important to plant functions. Reliability-centered maintenance (RCM) improves on the PM techniques by introducing a set of guidelines by which to evaluate the system functions. It also minimizes intrusive maintenance, labor, and equipment downtime without sacrificing system performance when its function is essential for plant safety. Both the PM and RCM approaches require that system reliability data be updated as more component failures and operation time are acquired. Systems reliability and the likelihood of component failures can be calculated by Bayesian statistical methods, which can update these data. The DATMAN computer code has been developed at Penn State to simplify the Bayesian analysis by performing tedious calculations needed for RCM reliability analysis. DATMAN reads data for updating, fits a distribution that best fits the data, and calculates component reliability. DATMAN provides a user-friendly interface menu that allows the user to choose from several common prior and posterior distributions, insert new failure data, and visually select the distribution that matches the data most accurately

  3. Sensitivity analysis in optimization and reliability problems

    International Nuclear Information System (INIS)

    Castillo, Enrique; Minguez, Roberto; Castillo, Carmen

    2008-01-01

    The paper starts giving the main results that allow a sensitivity analysis to be performed in a general optimization problem, including sensitivities of the objective function, the primal and the dual variables with respect to data. In particular, general results are given for non-linear programming, and closed formulas for linear programming problems are supplied. Next, the methods are applied to a collection of civil engineering reliability problems, which includes a bridge crane, a retaining wall and a composite breakwater. Finally, the sensitivity analysis formulas are extended to calculus of variations problems and a slope stability problem is used to illustrate the methods

  4. Analysis of the Effect of Construction and Operation of Thermal Expansion System Compounds on Steam Turbines Reliability

    Science.gov (United States)

    Murmansky, B. E.; Sosnovsky, A. Yu.; Brodov, Yu. M.

    2017-11-01

    The inspection results are presented of turbines of different types and capacity, showing the influence of various factors (such as increased frictional forces on the mating surfaces, clearance changes in the joints elements, TES elements design, state of the thermal expansions compensation system of pipelines) on the operation both of thermal expansion system and of the turbine as a whole. The data are presented on the effectiveness of various measures aimed to eliminate the causes of the turbine thermal expansion system deviations from its normal operation. The results are shown of the influence simulation of various factors (such as flanges and piping warming, ratio of clearance changes in the elements) on the probability of turbine TES hindrance. It is shown that clearance ratios employed in most turbines do not provide the stability of turbine TES against the external action of connected pipes. The simulation results permit to explain the bearing housings turns observed during inspections, resulting in a jam on the longitudinal keys, in temperature distribution changes on the thrust bearing pads, and in some cases in false readings of instruments rotor axial displacement.

  5. A study of operational and testing reliability in software reliability analysis

    International Nuclear Information System (INIS)

    Yang, B.; Xie, M.

    2000-01-01

    Software reliability is an important aspect of any complex equipment today. Software reliability is usually estimated based on reliability models such as nonhomogeneous Poisson process (NHPP) models. Software systems are improving in testing phase, while it normally does not change in operational phase. Depending on whether the reliability is to be predicted for testing phase or operation phase, different measure should be used. In this paper, two different reliability concepts, namely, the operational reliability and the testing reliability, are clarified and studied in detail. These concepts have been mixed up or even misused in some existing literature. Using different reliability concept will lead to different reliability values obtained and it will further lead to different reliability-based decisions made. The difference of the estimated reliabilities is studied and the effect on the optimal release time is investigated

  6. Selected Methods For Increases Reliability The Of Electronic Systems Security

    Directory of Open Access Journals (Sweden)

    Paś Jacek

    2015-11-01

    Full Text Available The article presents the issues related to the different methods to increase the reliability of electronic security systems (ESS for example, a fire alarm system (SSP. Reliability of the SSP in the descriptive sense is a property preservation capacity to implement the preset function (e.g. protection: fire airport, the port, logistics base, etc., at a certain time and under certain conditions, e.g. Environmental, despite the possible non-compliance by a specific subset of elements this system. Analyzing the available literature on the ESS-SSP is not available studies on methods to increase the reliability (several works similar topics but moving with respect to the burglary and robbery (Intrusion. Based on the analysis of the set of all paths in the system suitability of the SSP for the scenario mentioned elements fire events (device critical because of security.

  7. The development of a reliable amateur boxing performance analysis template.

    Science.gov (United States)

    Thomson, Edward; Lamb, Kevin; Nicholas, Ceri

    2013-01-01

    The aim of this study was to devise a valid performance analysis system for the assessment of the movement characteristics associated with competitive amateur boxing and assess its reliability using analysts of varying experience of the sport and performance analysis. Key performance indicators to characterise the demands of an amateur contest (offensive, defensive and feinting) were developed and notated using a computerised notational analysis system. Data were subjected to intra- and inter-observer reliability assessment using median sign tests and calculating the proportion of agreement within predetermined limits of error. For all performance indicators, intra-observer reliability revealed non-significant differences between observations (P > 0.05) and high agreement was established (80-100%) regardless of whether exact or the reference value of ±1 was applied. Inter-observer reliability was less impressive for both analysts (amateur boxer and experienced analyst), with the proportion of agreement ranging from 33-100%. Nonetheless, there was no systematic bias between observations for any indicator (P > 0.05), and the proportion of agreement within the reference range (±1) was 100%. A reliable performance analysis template has been developed for the assessment of amateur boxing performance and is available for use by researchers, coaches and athletes to classify and quantify the movement characteristics of amateur boxing.

  8. Research on Connection and Function Reliability of the Oil&Gas Pipeline System

    Directory of Open Access Journals (Sweden)

    Xu Bo

    2017-01-01

    Full Text Available Pipeline transportation is the optimal way for energy delivery in terms of safety, efficiency and environmental protection. Because of the complexity of pipeline external system including geological hazards, social and cultural influence, it is a great challenge to operate the pipeline safely and reliable. Therefore, the pipeline reliability becomes an important issue. Based on the classical reliability theory, the analysis of pipeline system is carried out, then the reliability model of the pipeline system is built, and the calculation is addressed thereafter. Further the connection and function reliability model is applied to a practical active pipeline system, with the use of the proposed methodology of the pipeline system; the connection reliability and function reliability are obtained. This paper firstly presented to considerate the connection and function reliability separately and obtain significant contribution to establish the mathematical reliability model of pipeline system, hence provide fundamental groundwork for the pipeline reliability research in the future.

  9. High-Reliable PLC RTOS Development and RPS Structure Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Sohn, H. S.; Song, D. Y.; Sohn, D. S.; Kim, J. H. [Enersys Co., Daejeon (Korea, Republic of)

    2008-04-15

    One of the KNICS objectives is to develop a platform for Nuclear Power Plant(NPP) I and C(Instrumentation and Control) system, especially plant protection system. The developed platform is POSAFE-Q and this work supports the development of POSAFE-Q with the development of high-reliable real-time operating system(RTOS) and programmable logic device(PLD) software. Another KNICS objective is to develop safety I and C systems, such as Reactor Protection System(RPS) and Engineered Safety Feature-Component Control System(ESF-CCS). This work plays an important role in the structure analysis for RPS. Validation and verification(V and V) of the safety critical software is an essential work to make digital plant protection system highly reliable and safe. Generally, the reliability and safety of software based system can be improved by strict quality assurance framework including the software development itself. In other words, through V and V, the reliability and safety of a system can be improved and the development activities like software requirement specification, software design specification, component tests, integration tests, and system tests shall be appropriately documented for V and V.

  10. Sensitivity based reduced approaches for structural reliability analysis

    Indian Academy of Sciences (India)

    the system parameters and the natural frequencies. For these reasons a scientific and systematic approach is required to predict the probability of failure of a structure at the design stage. Probabilistic structural reliability analysis is one such approach. This can be implemented in conjunction with the stochastic finite element ...

  11. Statistical models and methods for reliability and survival analysis

    CERN Document Server

    Couallier, Vincent; Huber-Carol, Catherine; Mesbah, Mounir; Huber -Carol, Catherine; Limnios, Nikolaos; Gerville-Reache, Leo

    2013-01-01

    Statistical Models and Methods for Reliability and Survival Analysis brings together contributions by specialists in statistical theory as they discuss their applications providing up-to-date developments in methods used in survival analysis, statistical goodness of fit, stochastic processes for system reliability, amongst others. Many of these are related to the work of Professor M. Nikulin in statistics over the past 30 years. The authors gather together various contributions with a broad array of techniques and results, divided into three parts - Statistical Models and Methods, Statistical

  12. Reliability of accumulators systems for Angra-I: a reavaluation

    International Nuclear Information System (INIS)

    Oliveira, L.F.S. de; Fleming, P.V.; Frutuoso e Melo, P.F.F.; Tayt-Sohn, L.C.

    1983-01-01

    A new evaluation of reliability analysis for accumulators systems of Angra-1, based on a study done in 1979/80 is done the methodology used is the same (WASH-1400). An additional point, a computer program was used to obtain the minimum cuts. (author) [pt

  13. Systems reliability Benchmark exercise part 1-Description and results

    International Nuclear Information System (INIS)

    Amendola, A.

    1986-01-01

    The report describes aims, rules and results of the Systems Reliability Benchmark Exercise, which has been performed in order to assess methods and procedures for reliability analysis of complex systems and involved a large number of European organizations active in NPP safety evaluation. The exercise included both qualitative and quantitative methods and was structured in such a way that separation of the effects of uncertainties in modelling and in data on the overall spread was made possible. Part I describes the way in which RBE has been performed, its main results and conclusions

  14. European Reliability Data System: main developments and use

    International Nuclear Information System (INIS)

    Amesz, J.; Capobianchi, S.; Kalfsbeek, H.W.; Mancini, G.

    1985-01-01

    The paper revises the aims and objectives of the European Reliability Data System (ERDS), a centralized system collecting and organizing information related to the operation of light water reactors. The paper first describes the recent developments of the four data banks constituting the system: Component Event Data Bank, Abnormal Occurrences Reporting System, Operating Unit Status Report and Reliability Parameters Data Bank. Then several issues are discussed referring mostly to the status of classification schemes and their use, to the operation of the banks (data input and transcoding) and to the retrieval and utilization of the information; in this latter case particularly the analysis potential of the data collection scheme of the AORS (Abnormal Occurrences Reporting System) is demonstrated. Finally, emphasis is given to the increasing role which artificial intelligence techniques such as natural language and expert systems and fuzzy logic may play in improving the future capabilities of the system

  15. Reliable neuronal systems: the importance of heterogeneity.

    Directory of Open Access Journals (Sweden)

    Johannes Lengler

    Full Text Available For every engineer it goes without saying: in order to build a reliable system we need components that consistently behave precisely as they should. It is also well known that neurons, the building blocks of brains, do not satisfy this constraint. Even neurons of the same type come with huge variances in their properties and these properties also vary over time. Synapses, the connections between neurons, are highly unreliable in forwarding signals. In this paper we argue that both these fact add variance to neuronal processes, and that this variance is not a handicap of neural systems, but that instead predictable and reliable functional behavior of neural systems depends crucially on this variability. In particular, we show that higher variance allows a recurrently connected neural population to react more sensitively to incoming signals, and processes them faster and more energy efficient. This, for example, challenges the general assumption that the intrinsic variability of neurons in the brain is a defect that has to be overcome by synaptic plasticity in the process of learning.

  16. Control system reliability at Jefferson Lab

    International Nuclear Information System (INIS)

    At Thomas Jefferson National Accelerator Facility (Jefferson Lab), the availability of the control system is crucial to the operation of the accelerator for experimental programs. Jefferson Lab's control system, uses 68040 based microprocessors running VxWorks, Unix workstations, and a variety of VME, CAMAC. GPIB, and serial devices. The software consists of control system toolkit software, commercial packages, and over 200 custom and generic applications, some of which are highly complex. The challenge is to keep this highly diverse and still growing system, with over 162,000 control points, operating reliably, while managing changes and upgrades to both the hardware and software. Downtime attributable to the control system includes the time to troubleshoot and repair problems and the time to restore the machine to operation of the scheduled program. This paper describes the availability of the control system during the last year, the heaviest contributors to downtime and the response to problems. Strategies for improving the robustness of the control system am detailed and include changes in hardware, software, procedures and processes. The improvements range from the routine preventive hardware maintenance, to improving their ability to detect, predict and prevent problems. This paper also describes the software tools used to assist in control system troubleshooting, maintenance and failure recovery processes

  17. Control system reliability at Jefferson Lab

    International Nuclear Information System (INIS)

    White, K.S.; Areti, H.; Garza, O.

    1997-01-01

    At Thomas Jefferson National Accelerator Facility (Jefferson Lab), the availability of the control system is crucial to the operation of the accelerator for experimental programs. Jefferson Lab's control system, uses 68040 based microprocessors running VxWorks, Unix workstations, and a variety of VME, CAMAC. GPIB, and serial devices. The software consists of control system toolkit software, commercial packages, and over 200 custom and generic applications, some of which are highly complex. The challenge is to keep this highly diverse and still growing system, with over 162,000 control points, operating reliably, while managing changes and upgrades to both the hardware and software. Downtime attributable to the control system includes the time to troubleshoot and repair problems and the time to restore the machine to operation of the scheduled program. This paper describes the availability of the control system during the last year, the heaviest contributors to downtime and the response to problems. Strategies for improving the robustness of the control system am detailed and include changes in hardware, software, procedures and processes. The improvements range from the routine preventive hardware maintenance, to improving their ability to detect, predict and prevent problems. This paper also describes the software tools used to assist in control system troubleshooting, maintenance and failure recovery processes

  18. Insights from a reliability review of digital plant protection system

    International Nuclear Information System (INIS)

    Kim, I.S.; Hwang, S.W.; Kim, B.S.; Jeong, C.H.; Oh, S.H.

    2001-01-01

    The full text follows: As part of the design efforts for Ulchin nuclear power plant units 5 and 6 of Korea, a reliability analysis of digital plant protection system (DPPS) was performed by ABB-CE. An independent review of the DPPS reliability analysis was undertaken by Hanyang University to assist Korea Institute of Nuclear Safety (KINS), the nuclear regulatory body of Korea, in evaluating the design acceptability of the digital system. The DPPS is designed to encompass both reactor trip function and ESFAS (engineered safety feature actuation system) initiation function. The major methods used by the ABB-CE to assess the Ulchin 5-6 DPPS reliability are failure mode and effect analysis (FMEA) and fault tree analysis. Hence, our independent review was conducted focusing on: -) the establishment of review criteria based on various sources, such as the standard review plan of KINS, 10CFR50 Appendix A, IEEE standards 279, 577, and 603; -) the suitability of the FMEA and fault tree analysis for the Ulchin 5-6 DPPS, including the specific methods used (e.g., for human reliability analysis and common-cause failure analysis), the assumptions made (e.g., with respect to test frequency and watchdog timer coverage), and the data employed (e.g., CCF parameter, human error probability, and processor failure rate); and -) the design acceptability of the DPPS especially as compared to the analog plant protection system from a reliability and safety perspective. The paper shall also discuss key issues requiring further in-depth investigation, such as reliability of programmable logic controllers (PLCs), coverage factor of watchdog timers, and susceptibility of redundant digital units to common cause failure. Sensitivity analyses were carried out to investigate the impact of several parameters of special interest, like the coverage factor of watchdog timer and human error probability (e.g. an operator error to manually trip the reactor, or to mis-calibrate the trip parameters) on

  19. Reliability of emergency ac power systems at nuclear power plants

    Energy Technology Data Exchange (ETDEWEB)

    Battle, R E; Campbell, D J

    1983-07-01

    Reliability of emergency onsite ac power systems at nuclear power plants has been questioned within the Nuclear Regulatory Commission (NRC) because of the number of diesel generator failures reported by nuclear plant licensees and the reactor core damage that could result from diesel failure during an emergency. This report contains the results of a reliability analysis of the onsite ac power system, and it uses the results of a separate analysis of offsite power systems to calculate the expected frequency of station blackout. Included is a design and operating experience review. Eighteen plants representative of typical onsite ac power systems and ten generic designs were selected to be modeled by fault trees. Operating experience data were collected from the NRC files and from nuclear plant licensee responses to a questionnaire sent out for this project.

  20. 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.

  1. An Introduction To Reliability

    International Nuclear Information System (INIS)

    Park, Kyoung Su

    1993-08-01

    This book introduces reliability with definition of reliability, requirement of reliability, system of life cycle and reliability, reliability and failure rate such as summary, reliability characteristic, chance failure, failure rate which changes over time, failure mode, replacement, reliability in engineering design, reliability test over assumption of failure rate, and drawing of reliability data, prediction of system reliability, conservation of system, failure such as summary and failure relay and analysis of system safety.

  2. Reliable control system for nuclear power plant

    International Nuclear Information System (INIS)

    Okamoto, Tetsuo; Miyazaki, Shiro

    1980-01-01

    The System 1100 for nuclear power plants is the measuring and control system which utilizes the features of the System 1100 for electric power market in addition to the results of nuclear instrumentation with EBS-ZN series, and it has the following features. The maintenance and inspection in operation are easy. The construction of control loops is made flexibly by the combination of modules. The construction of multi-variable control system using mainly feed forward control is easy. Such functions as the automatic switching of control modes can be included. The switching of manual and automatic operations is easy, and if some trouble occurred in a module, the manual operation can be made. The aseismatic ability is improved by rigid structure cubicles. Nonflammable materials are used for wires, multi-core cables, paints and printed boards. The anti-noise characteristics are improved, and the reliability is high. The policy of developing the System 1100 for nuclear power plants, the type approval tests on modules and units and the type approval test on the system are described. The items of the system type approval test were standard performance test, earthquake test, noise isolation test, temperature and humidity test, and drift test. The aseismatic cubicle showed good endurance in its vibration test. (Kako, I.)

  3. System reliability time-dependent models

    International Nuclear Information System (INIS)

    Debernardo, H.D.

    1991-06-01

    A probabilistic methodology for safety system technical specification evaluation was developed. The method for Surveillance Test Interval (S.T.I.) evaluation basically means an optimization of S.T.I. of most important system's periodically tested components. For Allowed Outage Time (A.O.T.) calculations, the method uses system reliability time-dependent models (A computer code called FRANTIC III). A new approximation, which was called Independent Minimal Cut Sets (A.C.I.), to compute system unavailability was also developed. This approximation is better than Rare Event Approximation (A.E.R.) and the extra computing cost is neglectible. A.C.I. was joined to FRANTIC III to replace A.E.R. on future applications. The case study evaluations verified that this methodology provides a useful probabilistic assessment of surveillance test intervals and allowed outage times for many plant components. The studied system is a typical configuration of nuclear power plant safety systems (two of three logic). Because of the good results, these procedures will be used by the Argentine nuclear regulatory authorities in evaluation of technical specification of Atucha I and Embalse nuclear power plant safety systems. (Author) [es

  4. Reliability of the Emergency Severity Index: Meta-analysis

    Directory of Open Access Journals (Sweden)

    Amir Mirhaghi

    2015-01-01

    Full Text Available Objectives: Although triage systems based on the Emergency Severity Index (ESI have many advantages in terms of simplicity and clarity, previous research has questioned their reliability in practice. Therefore, the aim of this meta-analysis was to determine the reliability of ESI triage scales. Methods: This metaanalysis was performed in March 2014. Electronic research databases were searched and articles conforming to the Guidelines for Reporting Reliability and Agreement Studies were selected. Two researchers independently examined selected abstracts. Data were extracted in the following categories: version of scale (latest/older, participants (adult/paediatric, raters (nurse, physician or expert, method of reliability (intra/inter-rater, reliability statistics (weighted/unweighted kappa and the origin and publication year of the study. The effect size was obtained by the Z-transformation of reliability coefficients. Data were pooled with random-effects models and a meta-regression was performed based on the method of moments estimator. Results: A total of 19 studies from six countries were included in the analysis. The pooled coefficient for the ESI triage scales was substantial at 0.791 (95% confidence interval: 0.787‒0.795. Agreement was higher with the latest and adult versions of the scale and among expert raters, compared to agreement with older and paediatric versions of the scales and with other groups of raters, respectively. Conclusion: ESI triage scales showed an acceptable level of overall reliability. However, ESI scales require more development in order to see full agreement from all rater groups. Further studies concentrating on other aspects of reliability assessment are needed.

  5. Maintenance management of railway infrastructures based on reliability analysis

    International Nuclear Information System (INIS)

    Macchi, Marco; Garetti, Marco; Centrone, Domenico; Fumagalli, Luca; Piero Pavirani, Gian

    2012-01-01

    Railway infrastructure maintenance plays a crucial role for rail transport. It aims at guaranteeing safety of operations and availability of railway tracks and related equipment for traffic regulation. Moreover, it is one major cost for rail transport operations. Thus, the increased competition in traffic market is asking for maintenance improvement, aiming at the reduction of maintenance expenditures while keeping the safety of operations. This issue is addressed by the methodology presented in the paper. The first step of the methodology consists of a family-based approach for the equipment reliability analysis; its purpose is the identification of families of railway items which can be given the same reliability targets. The second step builds the reliability model of the railway system for identifying the most critical items, given a required service level for the transportation system. The two methods have been implemented and tested in practical case studies, in the context of Rete Ferroviaria Italiana, the Italian public limited company for railway transportation.

  6. Demand Response as a System Reliability Resource

    Energy Technology Data Exchange (ETDEWEB)

    Eto, Joseph H. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Environmental Energy Technologies Division; Lewis, Nancy Jo [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Environmental Energy Technologies Division; Watson, David [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Environmental Energy Technologies Division; Kiliccote, Sila [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Environmental Energy Technologies Division; Auslander, David [Univ. of California, Berkeley, CA (United States); Paprotny, Igor [Univ. of California, Berkeley, CA (United States); Makarov, Yuri [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2012-12-31

    The Demand Response as a System Reliability Resource project consists of six technical tasks: • Task 2.1. Test Plan and Conduct Tests: Contingency Reserves Demand Response (DR) Demonstration—a pioneering demonstration of how existing utility load-management assets can provide an important electricity system reliability resource known as contingency reserve. • Task 2.2. Participation in Electric Power Research Institute (EPRI) IntelliGrid—technical assistance to the EPRI IntelliGrid team in developing use cases and other high-level requirements for the architecture. • Task 2.3. Research, Development, and Demonstration (RD&D) Planning for Demand Response Technology Development—technical support to the Public Interest Energy Research (PIER) Program on five topics: Sub-task 1. PIER Smart Grid RD&D Planning Document; Sub-task 2. System Dynamics of Programmable Controllable Thermostats; Sub-task 3. California Independent System Operator (California ISO) DR Use Cases; Sub-task 4. California ISO Telemetry Requirements; and Sub-task 5. Design of a Building Load Data Storage Platform. • Task 2.4. Time Value of Demand Response—research that will enable California ISO to take better account of the speed of the resources that it deploys to ensure compliance with reliability rules for frequency control. • Task 2.5. System Integration and Market Research: Southern California Edison (SCE)—research and technical support for efforts led by SCE to conduct demand response pilot demonstrations to provide a contingency reserve service (known as non-spinning reserve) through a targeted sub-population of aggregated residential and small commercial customers enrolled in SCE’s traditional air conditioning (AC) load cycling program, the Summer Discount Plan. • Task 2.6. Demonstrate Demand Response Technologies: Pacific Gas and Electric (PG&E)—research and technical support for efforts led by PG&E to conduct a demand response pilot demonstration to provide non

  7. 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).

  8. A high reliability oxygen deficiency monitoring system

    International Nuclear Information System (INIS)

    Parry, R.; Claborn, G.; Haas, A.; Landis, R.; Page, W.; Smith, J.

    1993-05-01

    The escalating use of cryogens at national laboratories in general and accelerators in particular, along with the increased emphasis placed on personnel safety, mandates the development and installation of oxygen monitoring systems to insure personnel safety in the event of a cryogenic leak. Numerous vendors offer oxygen deficiency monitoring systems but fail to provide important features and/or flexibility. This paper describes a unique oxygen monitoring system developed for the Magnet Test Laboratory (MTL) at the Superconducting Super Collider Laboratory (SSCL). Features include: high reliability, oxygen cell redundancy, sensor longevity, simple calibration, multiple trip points, offending sensor audio and visual indication, global alarms for building evacuation, local and remote analog readout, event and analog data logging, EMAIL event notification, phone line voice status system, and multi-drop communications network capability for reduced cable runs. Of particular importance is the distributed topology of the system which allows it to operate in a stand-alone configuration or to communicate with a host computer. This flexibility makes it ideal for small applications such as a small room containing a cryogenic dewar, as well as larger systems which monitor many offices and labs in several buildings

  9. Human Reliability Analysis for Digital Human-Machine Interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Ronald L. Boring

    2014-06-01

    This paper addresses the fact that existing human reliability analysis (HRA) methods do not provide guidance on digital human-machine interfaces (HMIs). Digital HMIs are becoming ubiquitous in nuclear power operations, whether through control room modernization or new-build control rooms. Legacy analog technologies like instrumentation and control (I&C) systems are costly to support, and vendors no longer develop or support analog technology, which is considered technologically obsolete. Yet, despite the inevitability of digital HMI, no current HRA method provides guidance on how to treat human reliability considerations for digital technologies.

  10. Bayesian networks inference algorithm to implement Dempster Shafer theory in reliability analysis

    International Nuclear Information System (INIS)

    Simon, C.; Weber, P.; Evsukoff, A.

    2008-01-01

    This paper deals with the use of Bayesian networks to compute system reliability. The reliability analysis problem is described and the usual methods for quantitative reliability analysis are presented within a case study. Some drawbacks that justify the use of Bayesian networks are identified. The basic concepts of the Bayesian networks application to reliability analysis are introduced and a model to compute the reliability for the case study is presented. Dempster Shafer theory to treat epistemic uncertainty in reliability analysis is then discussed and its basic concepts that can be applied thanks to the Bayesian network inference algorithm are introduced. Finally, it is shown, with a numerical example, how Bayesian networks' inference algorithms compute complex system reliability and what the Dempster Shafer theory can provide to reliability analysis

  11. Stochastic reliability analysis using Fokker Planck equations

    International Nuclear Information System (INIS)

    Hari Prasad, M.; Rami Reddy, G.; Srividya, A.; Verma, A.K.

    2011-01-01

    The Fokker-Planck equation describes the time evolution of the probability density function of the velocity of a particle, and can be generalized to other observables as well. It is also known as the Kolmogorov forward equation (diffusion). Hence, for any process, which evolves with time, the probability density function as a function of time can be represented with Fokker-Planck equation. In stochastic reliability analysis one is more interested in finding out the reliability or failure probability of the components or structures as a function of time rather than instantaneous failure probabilities. In this analysis the variables are represented with random processes instead of random variables. A random processes can be either stationary or non stationary. If the random process is stationary then the failure probability doesn't change with time where as in the case of non stationary processes the failure probability changes with time. In the present paper Fokker Planck equations have been used to find out the probability density function of the non stationary random processes. In this paper a flow chart has been provided which describes step by step process for carrying out stochastic reliability analysis using Fokker-Planck equations. As a first step one has to identify the failure function as a function of random processes. Then one has to solve the Fokker-Planck equation for each random process. In this paper the Fokker-Planck equation has been solved by using Finite difference method. As a result one gets the probability density values of the random process in the sample space as well as time space. Later at each time step appropriate probability distribution has to be identified based on the available probability density values. For checking the better fitness of the data Kolmogorov-Smirnov Goodness of fit test has been performed. In this way one can find out the distribution of the random process at each time step. Once one has the probability distribution

  12. Transmission embedded cost allocation methodology with consideration of system reliability

    International Nuclear Information System (INIS)

    Hur, D.; Park, J.-K.; Yoo, C.-I.; Kim, B.H.

    2004-01-01

    In a vertically integrated utility industry, the cost of reliability, as a separate service, has not received much rigorous analysis. However, as a cornerstone of restructuring the industry, the transmission service pricing must change to be consistent with, and supportive of, competitive wholesale electricity markets. This paper focuses on the equitable allocation of transmission network embedded costs including the transmission reliability cost based on the contributions of each generator to branch flows under normal conditions as well as the line outage impact factor under a variety of load levels. A numerical example on a six-bus system is given to illustrate the applications of the proposed methodology. (author)

  13. Application of modern reliability database techniques to military system data

    International Nuclear Information System (INIS)

    Bunea, Cornel; Mazzuchi, Thomas A.; Sarkani, Shahram; Chang, H.-C.

    2008-01-01

    This paper focuses on analysis techniques of modern reliability databases, with an application to military system data. The analysis of military system data base consists of the following steps: clean the data and perform operation on it in order to obtain good estimators; present simple plots of data; analyze the data with statistical and probabilistic methods. Each step is dealt with separately and the main results are presented. Competing risks theory is advocated as the mathematical support for the analysis. The general framework of competing risks theory is presented together with simple independent and dependent competing risks models available in literature. These models are used to identify the reliability and maintenance indicators required by the operating personnel. Model selection is based on graphical interpretation of plotted data

  14. Modeling and Analysis of Component Faults and Reliability

    DEFF Research Database (Denmark)

    Le Guilly, Thibaut; Olsen, Petur; Ravn, Anders Peter

    2016-01-01

    This chapter presents a process to design and validate models of reactive systems in the form of communicating timed automata. The models are extended with faults associated with probabilities of occurrence. This enables a fault tree analysis of the system using minimal cut sets that are automati......This chapter presents a process to design and validate models of reactive systems in the form of communicating timed automata. The models are extended with faults associated with probabilities of occurrence. This enables a fault tree analysis of the system using minimal cut sets...... that are automatically generated. The stochastic information on the faults is used to estimate the reliability of the fault affected system. The reliability is given with respect to properties of the system state space. We illustrate the process on a concrete example using the Uppaal model checker for validating...... the ideal system model and the fault modeling. Then the statistical version of the tool, UppaalSMC, is used to find reliability estimates....

  15. Reliability Analysis of an Offshore Structure

    DEFF Research Database (Denmark)

    Sørensen, John Dalsgaard; Thoft-Christensen, Palle; Rackwitz, R.

    1992-01-01

    variables are desenbed using spline fundion response surfaces. A Laplace integral expansion is used to estimate the time variant reliability. Parameter studies are performed for the reliability estimates and the results of the time variant and the time invariant reliability analyses are compared....

  16. Diagnostics and reliability of pipeline systems

    CERN Document Server

    Timashev, Sviatoslav

    2016-01-01

    The book contains solutions to fundamental problems which arise due to the logic of development of specific branches of science, which are related to pipeline safety, but mainly are subordinate to the needs of pipeline transportation.          The book deploys important but not yet solved aspects of reliability and safety assurance of pipeline systems, which are vital aspects not only for the oil and gas industry and, in general, fuel and energy industries , but also to virtually all contemporary industries and technologies. The volume will be useful to specialists and experts in the field of diagnostics/ inspection, monitoring, reliability and safety of critical infrastructures. First and foremost, it will be useful to the decision making persons —operators of different types of pipelines, pipeline diagnostics/inspection vendors, and designers of in-line –inspection (ILI) tools, industrial and ecological safety specialists, as well as to researchers and graduate students.

  17. Towards Reliable Integrated Services for Dependable Systems

    DEFF Research Database (Denmark)

    Schiøler, Henrik; Ravn, Anders Peter; Izadi-Zamanabadi, Roozbeh

    connections and a reliability management framework is suggested. We suggest a network layer level reliability management protocol RRSVP (Reliability Resource Reservation Protocol) as a counterpart of the RSVP for bandwidth and time resource management. Active and passive standby redundancy by background...... applications residing on alternative routes. Details are provided for the operation of RRRSVP based on reliability slack calculus. Conclusions summarize the considerations and give directions for future research....

  18. Exploitation examination of reliability of coal dust systems

    International Nuclear Information System (INIS)

    Dojchinovski, Ilija; Trajkovski, Kole

    1997-01-01

    Designers and operators wish is, long, failure free operation at designed parameters of every system. Always we know the system start up time, but we don't know how long this system will operate successfully. Because of that in this article is given a method how, step by step, to determine the reliability of the system. Reliability parameters are obtained from experimental and operational data. When reliability parameters are determined then it is very easy to compare reliability of similar systems, for example excavators, or different systems, such as truck and rubber band transport system. Practical use of the theory of reliability is by purchasing of the systems when manufacturers have to have and present reliability parameters and on this way we can decide which system satisfies our needs regarding the quality-price-reliability. Reliability can be practically used in system operation where: 1) system reliability is maintained with proper start, use and shutdown of the system; 2) a system reliability is maintained with good maintenance organization; 3) a system reliability is maintained with innovations and improvements with final purpose removing of the imperfections experienced through the operation. Reliability is very important parameter in power generation plants. (Author)

  19. HUMAN RELIABILITY ANALYSIS FOR COMPUTERIZED PROCEDURES

    Energy Technology Data Exchange (ETDEWEB)

    Ronald L. Boring; David I. Gertman; Katya Le Blanc

    2011-09-01

    This paper provides a characterization of human reliability analysis (HRA) issues for computerized procedures in nuclear power plant control rooms. It is beyond the scope of this paper to propose a new HRA approach or to recommend specific methods or refinements to those methods. Rather, this paper provides a review of HRA as applied to traditional paper-based procedures, followed by a discussion of what specific factors should additionally be considered in HRAs for computerized procedures. Performance shaping factors and failure modes unique to computerized procedures are highlighted. Since there is no definitive guide to HRA for paper-based procedures, this paper also serves to clarify the existing guidance on paper-based procedures before delving into the unique aspects of computerized procedures.

  20. Reliability analysis of steel-containment strength

    International Nuclear Information System (INIS)

    Greimann, L.G.; Fanous, F.; Wold-Tinsae, A.; Ketalaar, D.; Lin, T.; Bluhm, D.

    1982-06-01

    A best estimate and uncertainty assessment of the resistance of the St. Lucie, Cherokee, Perry, WPPSS and Browns Ferry containment vessels was performed. The Monte Carlo simulation technique and second moment approach were compared as a means of calculating the probability distribution of the containment resistance. A uniform static internal pressure was used and strain ductility was taken as the failure criterion. Approximate methods were developed and calibrated with finite element analysis. Both approximate and finite element analyses were performed on the axisymmetric containment structure. An uncertainty assessment of the containment strength was then performed by the second moment reliability method. Based upon the approximate methods, the cumulative distribution for the resistance of each of the five containments (shell modes only) is presented

  1. Accident Sequence Evaluation Program: Human reliability analysis procedure

    International Nuclear Information System (INIS)

    Swain, A.D.

    1987-02-01

    This document presents a shortened version of the procedure, models, and data for human reliability analysis (HRA) which are presented in the Handbook of Human Reliability Analysis With emphasis on Nuclear Power Plant Applications (NUREG/CR-1278, August 1983). This shortened version was prepared and tried out as part of the Accident Sequence Evaluation Program (ASEP) funded by the US Nuclear Regulatory Commission and managed by Sandia National Laboratories. The intent of this new HRA procedure, called the ''ASEP HRA Procedure,'' is to enable systems analysts, with minimal support from experts in human reliability analysis, to make estimates of human error probabilities and other human performance characteristics which are sufficiently accurate for many probabilistic risk assessments. The ASEP HRA Procedure consists of a Pre-Accident Screening HRA, a Pre-Accident Nominal HRA, a Post-Accident Screening HRA, and a Post-Accident Nominal HRA. The procedure in this document includes changes made after tryout and evaluation of the procedure in four nuclear power plants by four different systems analysts and related personnel, including human reliability specialists. The changes consist of some additional explanatory material (including examples), and more detailed definitions of some of the terms. 42 refs

  2. Accident Sequence Evaluation Program: Human reliability analysis procedure

    Energy Technology Data Exchange (ETDEWEB)

    Swain, A.D.

    1987-02-01

    This document presents a shortened version of the procedure, models, and data for human reliability analysis (HRA) which are presented in the Handbook of Human Reliability Analysis With emphasis on Nuclear Power Plant Applications (NUREG/CR-1278, August 1983). This shortened version was prepared and tried out as part of the Accident Sequence Evaluation Program (ASEP) funded by the US Nuclear Regulatory Commission and managed by Sandia National Laboratories. The intent of this new HRA procedure, called the ''ASEP HRA Procedure,'' is to enable systems analysts, with minimal support from experts in human reliability analysis, to make estimates of human error probabilities and other human performance characteristics which are sufficiently accurate for many probabilistic risk assessments. The ASEP HRA Procedure consists of a Pre-Accident Screening HRA, a Pre-Accident Nominal HRA, a Post-Accident Screening HRA, and a Post-Accident Nominal HRA. The procedure in this document includes changes made after tryout and evaluation of the procedure in four nuclear power plants by four different systems analysts and related personnel, including human reliability specialists. The changes consist of some additional explanatory material (including examples), and more detailed definitions of some of the terms. 42 refs.

  3. The Development of a Demonstration Passive System Reliability Assessment

    Energy Technology Data Exchange (ETDEWEB)

    Bucknor, Matthew; Grabaskas, David; Brunett, Acacia

    2014-06-22

    In this paper, the details of the development of a demonstration problem to assess the reliability of a passive safety system are presented. An advanced small modular reactor (advSMR) design, which is a pool-type sodium fast reactor (SFR) coupled with a passive reactor cavity cooling system (RCCS) is described. The RELAP5-3D models of the advSMR and RCCS that will be used to simulate a long-term station blackout (SBO) accident scenario are presented. Proposed benchmarking techniques for both the reactor and the RCCS are discussed, which includes utilization of experimental results from the Natural convection Shutdown heat removal Test Facility (NSTF) at the Argonne National Laboratory. Details of how mechanistic methods, specifically the Reliability Method for Passive Systems (RMPS) approach, will be utilized to determine passive system reliability are presented. The results of this mechanistic analysis will ultimately be compared to results from dynamic methods in future work. This work is part of an ongoing project at Argonne to demonstrate methodologies for assessing passive system reliability.

  4. Design-related influencing factors of the computerized procedure system for inclusion into human reliability analysis of the advanced control room

    International Nuclear Information System (INIS)

    Kim, Jaewhan; Lee, Seung Jun; Jang, Seung Cheol; Ahn, Kwang-Il; Shin, Yeong Cheol

    2013-01-01

    This paper presents major design factors of the computerized procedure system (CPS) by task characteristics/requirements, with individual relative weight evaluated by the analytic hierarchy process (AHP) technique, for inclusion into human reliability analysis (HRA) of the advanced control rooms. Task characteristics/requirements of an individual procedural step are classified into four categories according to the dynamic characteristics of an emergency situation: (1) a single-static step, (2) a single-dynamic and single-checking step, (3) a single-dynamic and continuous-monitoring step, and (4) a multiple-dynamic and continuous-monitoring step. According to the importance ranking evaluation by the AHP technique, ‘clearness of the instruction for taking action’, ‘clearness of the instruction and its structure for rule interpretation’, and ‘adequate provision of requisite information’ were rated as of being higher importance for all the task classifications. Importance of ‘adequacy of the monitoring function’ and ‘adequacy of representation of the dynamic link or relationship between procedural steps’ is dependent upon task characteristics. The result of the present study gives a valuable insight on which design factors of the CPS should be incorporated, with relative importance or weight between design factors, into HRA of the advanced control rooms. (author)

  5. Statistical reliability assessment of software-based systems

    Energy Technology Data Exchange (ETDEWEB)

    Korhonen, J. [VTT Electronics, Espoo (Finland); Pulkkinen, U.; Haapanen, P. [VTT Automation, Espoo (Finland)

    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.).

  6. 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.)

  7. Pump system characterization and reliability enhancement

    International Nuclear Information System (INIS)

    Staunton, R.H.

    1998-01-01

    Pump characterization studies were performed at the Oak Ridge National Laboratory (ORNL) to review and analyze six years (1990-1995) of data from pump systems at domestic nuclear plants. The studies considered not only pumps and pump motors but also pump-related circuit breakers and turbine drives (i.e., the pump system). One significant finding was that the number of 'significant' failures of the pump circuit breaker exceeds the number of significant failures of the pump itself. The study also shows how regulatory code testing was designed for the pump only and therefore did not lead to the discovery of other significant pump system failures. Potential diagnostic technologies, both experimental and mature, suitable for on-line and off-line pump testing were identified. The study does not select or recommend technologies but proposes diagnostic technologies and monitoring techniques that should be further evaluated/developed for making meaningful and critically-needed improvements in the reliability of the pump system. (author)

  8. Energy-based dynamic reliability analysis

    International Nuclear Information System (INIS)

    Fukushima, S.; Mizutani, M.; Akao, Y.; Katukura, H.

    1993-01-01

    Dynamic reliability analysis (DRA) of structures subjected to strong ground motions is one of the most important parts of the safety assessment of structures. So far many DRA methods based on probabilistic theory have been developed. Generally, DRA methods are divided into three phases; seismic hazard analysis, fragility synthesis, and evaluation of probability of failure. In most DRA method, the seismic hazard curves of peak ground acceleration (PGA) or spectral acceleration at a certain period is evaluated to show the occurrence ratio of input motion in the seismic hazard analysis, and, in the fragility synthesis, random vibration theory is adopted to calculate the conditional probability of failure of structures given the occurrence of input motion. Since random vibration theory is developed in the frequency domain, PGAs are transformed into information in the frequency domain by means of introducing so-called peak factors and power spectra. This fact suggests that it is more convenient for DRA researchers to define the seismic hazardous the indices defined in the frequency domain from the first. In this paper, DRAs based on the two indices, i.e. PGA and total energy, are investigated in detail. Through the study, features and issues of DRA based on the total energy (hereafter called EDRA) are clarified from the viewpoint of the responses of the structure. (author)

  9. Task Decomposition in Human Reliability Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Boring, Ronald Laurids [Idaho National Laboratory; Joe, Jeffrey Clark [Idaho National Laboratory

    2014-06-01

    In the probabilistic safety assessments (PSAs) used in the nuclear industry, human failure events (HFEs) are determined as a subset of hardware failures, namely those hardware failures that could be triggered by human action or inaction. This approach is top-down, starting with hardware faults and deducing human contributions to those faults. Elsewhere, more traditionally human factors driven approaches would tend to look at opportunities for human errors first in a task analysis and then identify which of those errors is risk significant. The intersection of top-down and bottom-up approaches to defining HFEs has not been carefully studied. Ideally, both approaches should arrive at the same set of HFEs. This question remains central as human reliability analysis (HRA) methods are generalized to new domains like oil and gas. The HFEs used in nuclear PSAs tend to be top-down— defined as a subset of the PSA—whereas the HFEs used in petroleum quantitative risk assessments (QRAs) are more likely to be bottom-up—derived from a task analysis conducted by human factors experts. The marriage of these approaches is necessary in order to ensure that HRA methods developed for top-down HFEs are also sufficient for bottom-up applications.

  10. Reliability Analysis of a Green Roof Under Different Storm Scenarios

    Science.gov (United States)

    William, R. K.; Stillwell, A. S.

    2015-12-01

    Urban environments continue to face the challenges of localized flooding and decreased water quality brought on by the increasing amount of impervious area in the built environment. Green infrastructure provides an alternative to conventional storm sewer design by using natural processes to filter and store stormwater at its source. However, there are currently few consistent standards available in North America to ensure that installed green infrastructure is performing as expected. This analysis offers a method for characterizing green roof failure using a visual aid commonly used in earthquake engineering: fragility curves. We adapted the concept of the fragility curve based on the efficiency in runoff reduction provided by a green roof compared to a conventional roof under different storm scenarios. We then used the 2D distributed surface water-groundwater coupled model MIKE SHE to model the impact that a real green roof might have on runoff in different storm events. We then employed a multiple regression analysis to generate an algebraic demand model that was input into the Matlab-based reliability analysis model FERUM, which was then used to calculate the probability of failure. The use of reliability analysis as a part of green infrastructure design code can provide insights into green roof weaknesses and areas for improvement. It also supports the design of code that is more resilient than current standards and is easily testable for failure. Finally, the understanding of reliability of a single green roof module under different scenarios can support holistic testing of system reliability.

  11. Reliability analysis based on the losses from failures.

    Science.gov (United States)

    Todinov, M T

    2006-04-01

    The conventional reliability analysis is based on the premise that increasing the reliability of a system will decrease the losses from failures. On the basis of counterexamples, it is demonstrated that this is valid only if all failures are associated with the same losses. In case of failures associated with different losses, a system with larger reliability is not necessarily characterized by smaller losses from failures. Consequently, a theoretical framework and models are proposed for a reliability analysis, linking reliability and the losses from failures. Equations related to the distributions of the potential losses from failure have been derived. It is argued that the classical risk equation only estimates the average value of the potential losses from failure and does not provide insight into the variability associated with the potential losses. Equations have also been derived for determining the potential and the expected losses from failures for nonrepairable and repairable systems with components arranged in series, with arbitrary life distributions. The equations are also valid for systems/components with multiple mutually exclusive failure modes. The expected losses given failure is a linear combination of the expected losses from failure associated with the separate failure modes scaled by the conditional probabilities with which the failure modes initiate failure. On this basis, an efficient method for simplifying complex reliability block diagrams has been developed. Branches of components arranged in series whose failures are mutually exclusive can be reduced to single components with equivalent hazard rate, downtime, and expected costs associated with intervention and repair. A model for estimating the expected losses from early-life failures has also been developed. For a specified time interval, the expected losses from early-life failures are a sum of the products of the expected number of failures in the specified time intervals covering the

  12. The DYLAM approach to systems safety and reliability assessment

    International Nuclear Information System (INIS)

    Amendola, A.

    1988-01-01

    A survey of the principal features and applications of DYLAM (Dynamic Logical Analytical Methodology) is presented, whose basic principles can be summarized as follows: after a particular modelling of the component states, computerized heuristical procedures generate stochastic configurations of the system, whereas the resulting physical processes are simultaneously simulated to give account of the possible interactions between physics and states and, on the other hand, to search for system dangerous configurations and related probabilities. The association of probabilistic techniques for describing the states with physical equations for describing the process results in a very powerful tool for safety and reliability assessment of systems potentially subjected to dangerous incidental transients. A comprehensive picture of DYLAM capability for manifold applications can be obtained by the review of the study cases analyzed (LMFBR core accident, systems reliability assessment, accident simulation, man-machine interaction analysis, chemical reactors safety, etc.)

  13. Application of the Bayes equation to predicting reactor system reliability

    International Nuclear Information System (INIS)

    Fullwood, R.R.; Erdmann, R.C.; Rumble, E.T.; Lellouche, G.S.

    1977-01-01

    Reliability predictions for systems exhibiting few, if any, failures require the use of all available information. The Bayes equation incorporates prior engineering information with test data to provide statistically improved posterior estimates. Classical results agree with those obtained from the Bayes equation by using no prior information. For the case of failure-on-demand, this is equivalent to assuming a 50% mean failure probability for the prior information--hardly an appropriate estimate for a reliable system such as a reactor scram system. The method of Bayes conjugates applied to the cases of aging failure and failure-on-demand yields formulas for calculating mean, standard deviation, and confidence values. Various methods for incorporating prior information are possible. For example, calculating scram failure probabilities by incorporating prior information obtained from fault tree analysis of a scram system with historical test data indicates a mean scram failure probability of approx. 8 x 10 -6 per demand

  14. Reliability analysis with linguistic data: An evidential network approach

    International Nuclear Information System (INIS)

    Zhang, Xiaoge; Mahadevan, Sankaran; Deng, Xinyang

    2017-01-01

    In practical applications of reliability assessment of a system in-service, information about the condition of a system and its components is often available in text form, e.g., inspection reports. Estimation of the system reliability from such text-based records becomes a challenging problem. In this paper, we propose a four-step framework to deal with this problem. In the first step, we construct an evidential network with the consideration of available knowledge and data. Secondly, we train a Naive Bayes text classification algorithm based on the past records. By using the trained Naive Bayes algorithm to classify the new records, we build interval basic probability assignments (BPA) for each new record available in text form. Thirdly, we combine the interval BPAs of multiple new records using an evidence combination approach based on evidence theory. Finally, we propagate the interval BPA through the evidential network constructed earlier to obtain the system reliability. Two numerical examples are used to demonstrate the efficiency of the proposed method. We illustrate the effectiveness of the proposed method by comparing with Monte Carlo Simulation (MCS) results. - Highlights: • We model reliability analysis with linguistic data using evidential network. • Two examples are used to demonstrate the efficiency of the proposed method. • We compare the results with Monte Carlo Simulation (MCS).

  15. Finite element reliability analysis of fatigue life

    International Nuclear Information System (INIS)

    Harkness, H.H.; Belytschko, T.; Liu, W.K.

    1992-01-01

    Fatigue reliability is addressed by the first-order reliability method combined with a finite element method. Two-dimensional finite element models of components with cracks in mode I are considered with crack growth treated by the Paris law. Probability density functions of the variables affecting fatigue are proposed to reflect a setting where nondestructive evaluation is used, and the Rosenblatt transformation is employed to treat non-Gaussian random variables. Comparisons of the first-order reliability results and Monte Carlo simulations suggest that the accuracy of the first-order reliability method is quite good in this setting. Results show that the upper portion of the initial crack length probability density function is crucial to reliability, which suggests that if nondestructive evaluation is used, the probability of detection curve plays a key role in reliability. (orig.)

  16. The advantages of reliability centered maintenance for standby safety systems

    International Nuclear Information System (INIS)

    Dam, R.F.; Ayazzudin, S.; Nickerson, J.H.; DeLong, A.I.

    2002-01-01

    predictive monitoring. The testing in this strategy is part of an effort to ensure that the desired function is not only available today, but will be available tomorrow as well. This paper considers the application of a streamlined form of RCM to the Emergency Core Cooling (ECC) and Standby Generator (SG) Systems of a CANDU plant. Recently completed studies provide useful insight into the important value added of the systematic assessment approach (using RCM techniques) for these standby safety systems. In the case of RCM analysis performed on the Emergency Core Cooling (ECC) System of Point Lepreau Nuclear Power Generating Station (PLGS), it was found that 60% of the current maintenance tasks are testing (functional, stroke, logic, and annunciation tests). Similarly, the SGs have 50% of the maintenance tasks associated with testing. The paper considers how the results of the RCM analysis demonstrate that the analysis can be used to assist in the optimization of the testing program dictated by reliability while also taking better advantage of the testing through condition monitoring and predictive maintenance techniques. Further, the results illustrate the importance of identifying and linking the different plant activities within a well integrated plant culture. (author)

  17. Reliability analysis of an offshore structure

    DEFF Research Database (Denmark)

    Sorensen, J. D.; Faber, M. H.; Thoft-Christensen, P.

    1992-01-01

    A jacket type offshore structure from the North Sea is considered. The time variant reliability is estimated for failure defined as brittle fracture and crack through the tubular member walls. The stochastic modelling is described. The hot spot stress spectral moments as function of the stochastic...... variables are described using spline function response surfaces. A Laplace integral expansion is used to estimate the time variant reliability. Parameter studies are performed for the reliability estimates and the results of the time variant and the time invariant reliability analyses are compared. (Authors)...

  18. A framework for intelligent reliability centered maintenance analysis

    International Nuclear Information System (INIS)

    Cheng Zhonghua; Jia Xisheng; Gao Ping; Wu Su; Wang Jianzhao

    2008-01-01

    To improve the efficiency of reliability-centered maintenance (RCM) analysis, case-based reasoning (CBR), as a kind of artificial intelligence (AI) technology, was successfully introduced into RCM analysis process, and a framework for intelligent RCM analysis (IRCMA) was studied. The idea for IRCMA is based on the fact that the historical records of RCM analysis on similar items can be referenced and used for the current RCM analysis of a new item. Because many common or similar items may exist in the analyzed equipment, the repeated tasks of RCM analysis can be considerably simplified or avoided by revising the similar cases in conducting RCM analysis. Based on the previous theory studies, an intelligent RCM analysis system (IRCMAS) prototype was developed. This research has focused on the description of the definition, basic principles as well as a framework of IRCMA, and discussion of critical techniques in the IRCMA. Finally, IRCMAS prototype is presented based on a case study

  19. Composite system reliability evaluation by stochastic calculation of system operation

    Energy Technology Data Exchange (ETDEWEB)

    Haubrick, H.-J.; Hinz, H.-J.; Landeck, E. [Dept. of Power Systems and Power Economics (Germany)

    1994-12-31

    This report describes a new developed probabilistic approach for steady-state composite system reliability evaluation and its exemplary application to a bulk power test system. The new computer program called PHOENIX takes into consideration transmission limitations, outages of lines and power stations and, as a central element, a highly sophisticated model to the dispatcher performing remedial actions after disturbances. The kernel of the new method is a procedure for optimal power flow calculation that has been specially adapted for the use in reliability evaluations under the above mentioned conditions. (author) 11 refs., 8 figs., 1 tab.

  20. Reliability engineering for nuclear and other high technology systems

    International Nuclear Information System (INIS)

    Lakner, A.A.; Anderson, R.T.

    1985-01-01

    This book is written for the reliability instructor, program manager, system engineer, design engineer, reliability engineer, nuclear regulator, probability risk assessment (PRA) analyst, general manager and others who are involved in system hardware acquisition, design and operation and are concerned with plant safety and operational cost-effectiveness. It provides criteria, guidelines and comprehensive engineering data affecting reliability; it covers the key aspects of system reliability as it relates to conceptual planning, cost tradeoff decisions, specification, contractor selection, design, test and plant acceptance and operation. It treats reliability as an integrated methodology, explicitly describing life cycle management techniques as well as the basic elements of a total hardware development program, including: reliability parameters and design improvement attributes, reliability testing, reliability engineering and control. It describes how these elements can be defined during procurement, and implemented during design and development to yield reliable equipment. (author)

  1. Reliability Analysis and Optimal Design of Monolithic Vertical Wall Breakwaters

    DEFF Research Database (Denmark)

    Sørensen, John Dalsgaard; Burcharth, Hans F.; Christiani, E.

    1994-01-01

    Reliability analysis and reliability-based design of monolithic vertical wall breakwaters are considered. Probabilistic models of the most important failure modes, sliding failure, failure of the foundation and overturning failure are described . Relevant design variables are identified and relia...

  2. Adjoint sensitivity analysis of dynamic reliability models based on Markov chains - II: Application to IFMIF reliability assessment

    International Nuclear Information System (INIS)

    Cacuci, D. G.; Cacuci, D. G.; Balan, I.; Ionescu-Bujor, M.

    2008-01-01

    In Part II of this work, the adjoint sensitivity analysis procedure developed in Part I is applied to perform sensitivity analysis of several dynamic reliability models of systems of increasing complexity, culminating with the consideration of the International Fusion Materials Irradiation Facility (IFMIF) accelerator system. Section II presents the main steps of a procedure for the automated generation of Markov chains for reliability analysis, including the abstraction of the physical system, construction of the Markov chain, and the generation and solution of the ensuing set of differential equations; all of these steps have been implemented in a stand-alone computer code system called QUEFT/MARKOMAG-S/MCADJSEN. This code system has been applied to sensitivity analysis of dynamic reliability measures for a paradigm '2-out-of-3' system comprising five components and also to a comprehensive dynamic reliability analysis of the IFMIF accelerator system facilities for the average availability and, respectively, the system's availability at the final mission time. The QUEFT/MARKOMAG-S/MCADJSEN has been used to efficiently compute sensitivities to 186 failure and repair rates characterizing components and subsystems of the first-level fault tree of the IFMIF accelerator system. (authors)

  3. A new efficient algorithm for computing the imprecise reliability of monotone systems

    International Nuclear Information System (INIS)

    Utkin, Lev V.

    2004-01-01

    Reliability analysis of complex systems by partial information about reliability of components and by different conditions of independence of components may be carried out by means of the imprecise probability theory which provides a unified framework (natural extension, lower and upper previsions) for computing the system reliability. However, the application of imprecise probabilities to reliability analysis meets with a complexity of optimization problems which have to be solved for obtaining the system reliability measures. Therefore, an efficient simplified algorithm to solve and decompose the optimization problems is proposed in the paper. This algorithm allows us to practically implement reliability analysis of monotone systems under partial and heterogeneous information about reliability of components and under conditions of the component independence or the lack of information about independence. A numerical example illustrates the algorithm

  4. Analogical reasoning for reliability analysis based on generic data

    Energy Technology Data Exchange (ETDEWEB)

    Kozin, Igor O

    1996-10-01

    The paper suggests using the systemic concept 'analogy' for the foundation of an approach to analyze system reliability on the basis of generic data, describing the method of structuring the set that defines analogical models, an approach of transition from the analogical model to a reliability model and a way of obtaining reliability intervals of analogous objects.

  5. Analogical reasoning for reliability analysis based on generic data

    International Nuclear Information System (INIS)

    Kozin, Igor O.

    1996-01-01

    The paper suggests using the systemic concept 'analogy' for the foundation of an approach to analyze system reliability on the basis of generic data, describing the method of structuring the set that defines analogical models, an approach of transition from the analogical model to a reliability model and a way of obtaining reliability intervals of analogous objects

  6. Physical-Mechanisms Based Reliability Analysis For Emerging Technologies

    Science.gov (United States)

    2017-05-05

    AFRL-AFOSR-VA-TR-2017-0095 PHYSICAL -MECHANISMS BASED RELIABILITY ANALYSIS FOR EMERGING TECHNOLOGIES Ron Schrimpf VANDERBILT UNIVERSITY 110 21ST...SUBTITLE PHYSICAL -MECHANISMS BASED RELIABILITY ANALYSIS FOR EMERGING TECHNOLOGIES 5a.  CONTRACT NUMBER 5b.  GRANT NUMBER FA9550-11-1-0307 5c.  PROGRAM...which reliability models can be built. Thus, it is important to develop more predictive reliability models for advanced technologies, based on physical

  7. Response and Reliability Problems of Dynamic Systems

    DEFF Research Database (Denmark)

    Nielsen, Søren R. K.

    The present thesis consists of selected parts of the work performed by the author on stochastic dynamics and reliability theory of dynamically excited structures primarily during the period 1986-1996.......The present thesis consists of selected parts of the work performed by the author on stochastic dynamics and reliability theory of dynamically excited structures primarily during the period 1986-1996....

  8. Individual Differences in Human Reliability Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Jeffrey C. Joe; Ronald L. Boring

    2014-06-01

    While human reliability analysis (HRA) methods include uncertainty in quantification, the nominal model of human error in HRA typically assumes that operator performance does not vary significantly when they are given the same initiating event, indicators, procedures, and training, and that any differences in operator performance are simply aleatory (i.e., random). While this assumption generally holds true when performing routine actions, variability in operator response has been observed in multiple studies, especially in complex situations that go beyond training and procedures. As such, complexity can lead to differences in operator performance (e.g., operator understanding and decision-making). Furthermore, psychological research has shown that there are a number of known antecedents (i.e., attributable causes) that consistently contribute to observable and systematically measurable (i.e., not random) differences in behavior. This paper reviews examples of individual differences taken from operational experience and the psychological literature. The impact of these differences in human behavior and their implications for HRA are then discussed. We propose that individual differences should not be treated as aleatory, but rather as epistemic. Ultimately, by understanding the sources of individual differences, it is possible to remove some epistemic uncertainty from analyses.

  9. Space Mission Human Reliability Analysis (HRA) Project

    Science.gov (United States)

    Boyer, Roger

    2014-01-01

    The purpose of the Space Mission Human Reliability Analysis (HRA) Project is to extend current ground-based HRA risk prediction techniques to a long-duration, space-based tool. Ground-based HRA methodology has been shown to be a reasonable tool for short-duration space missions, such as Space Shuttle and lunar fly-bys. However, longer-duration deep-space missions, such as asteroid and Mars missions, will require the crew to be in space for as long as 400 to 900 day missions with periods of extended autonomy and self-sufficiency. Current indications show higher risk due to fatigue, physiological effects due to extended low gravity environments, and others, may impact HRA predictions. For this project, Safety & Mission Assurance (S&MA) will work with Human Health & Performance (HH&P) to establish what is currently used to assess human reliabiilty for human space programs, identify human performance factors that may be sensitive to long duration space flight, collect available historical data, and update current tools to account for performance shaping factors believed to be important to such missions. This effort will also contribute data to the Human Performance Data Repository and influence the Space Human Factors Engineering research risks and gaps (part of the HRP Program). An accurate risk predictor mitigates Loss of Crew (LOC) and Loss of Mission (LOM).The end result will be an updated HRA model that can effectively predict risk on long-duration missions.

  10. Semantic Web for Reliable Citation Analysis in Scholarly Publishing

    Directory of Open Access Journals (Sweden)

    Ruben Tous

    2011-03-01

    Full Text Available Analysis of the impact of scholarly artifacts is constrained by current unreliable practices in cross-referencing, citation discovering, and citation indexing and analysis, which have not kept pace with the technological advances that are occurring in several areas like knowledge management and security. Because citation analysis has become the primary component in scholarly impact factor calculation, and considering the relevance of this metric within both the scholarly publishing value chain and (especially important the professional curriculum evaluation of scholarly professionals, we defend that current practices need to be revised. This paper describes a reference architecture that aims to provide openness and reliability to the citation-tracking lifecycle. The solution relies on the use of digitally signed semantic metadata in the different stages of the scholarly publishing workflow in such a manner that authors, publishers, repositories, and citation-analysis systems will have access to independent reliable evidences that are resistant to forgery, impersonation, and repudiation. As far as we know, this is the first paper to combine Semantic Web technologies and public-key cryptography to achieve reliable citation analysis in scholarly publishing

  11. Digital System Reliability Test for the Evaluation of safety Critical Software of Digital Reactor Protection System

    Directory of Open Access Journals (Sweden)

    Hyun-Kook Shin

    2006-08-01

    Full Text Available A new Digital Reactor Protection System (DRPS based on VME bus Single Board Computer has been developed by KOPEC to prevent software Common Mode Failure(CMF inside digital system. The new DRPS has been proved to be an effective digital safety system to prevent CMF by Defense-in-Depth and Diversity (DID&D analysis. However, for practical use in Nuclear Power Plants, the performance test and the reliability test are essential for the digital system qualification. In this study, a single channel of DRPS prototype has been manufactured for the evaluation of DRPS capabilities. The integrated functional tests are performed and the system reliability is analyzed and tested. The results of reliability test show that the application software of DRPS has a very high reliability compared with the analog reactor protection systems.

  12. Reliability

    OpenAIRE

    Condon, David; Revelle, William

    2017-01-01

    Separating the signal in a test from the irrelevant noise is a challenge for all measurement. Low test reliability limits test validity, attenuates important relationships, and can lead to regression artifacts. Multiple approaches to the assessment and improvement of reliability are discussed. The advantages and disadvantages of several different approaches to reliability are considered. Practical advice on how to assess reliability using open source software is provided.

  13. Improvement of the Reliability Graph with General Gates to Analyze the Reliability of Dynamic Systems That Have Various Operation Modes

    Directory of Open Access Journals (Sweden)

    Seung Ki Shin

    2016-04-01

    Full Text Available The safety of nuclear power plants is analyzed by a probabilistic risk assessment, and the fault tree analysis is the most widely used method for a risk assessment with the event tree analysis. One of the well-known disadvantages of the fault tree is that drawing a fault tree for a complex system is a very cumbersome task. Thus, several graphical modeling methods have been proposed for the convenient and intuitive modeling of complex systems. In this paper, the reliability graph with general gates (RGGG method, one of the intuitive graphical modeling methods based on Bayesian networks, is improved for the reliability analyses of dynamic systems that have various operation modes with time. A reliability matrix is proposed and it is explained how to utilize the reliability matrix in the RGGG for various cases of operation mode changes. The proposed RGGG with a reliability matrix provides a convenient and intuitive modeling of various operation modes of complex systems, and can also be utilized with dynamic nodes that analyze the failure sequences of subcomponents. The combinatorial use of a reliability matrix with dynamic nodes is illustrated through an application to a shutdown cooling system in a nuclear power plant.

  14. Fatigue Reliability of Offshore Wind Turbine Systems

    DEFF Research Database (Denmark)

    Marquez-Dominguez, Sergio; Sørensen, John Dalsgaard

    2012-01-01

    Optimization of the design of offshore wind turbine substructures with respect to fatigue loads is an important issue in offshore wind energy. A stochastic model is developed for assessing the fatigue failure reliability. This model can be used for direct probabilistic design and for calibration...... of appropriate partial safety factors / fatigue design factors (FDF) for steel substructures of offshore wind turbines (OWTs). The fatigue life is modeled by the SN approach. Design and limit state equations are established based on the accumulated fatigue damage. The acceptable reliability level for optimal...... fatigue design of OWTs is discussed and results for reliability assessment of typical fatigue critical design of offshore steel support structures are presented....

  15. Predictive analysis on the electric energy distribution systems reliability: applying the synerGEE system; Analisis predictivo de la confiabilidad en los sistemas de distribucion de energia electrica: aplicando el sistema synerGEE

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez Andrade, Carlos

    2008-12-15

    Electrical distribution systems ought to deliver electric power as economical as possible with an acceptable degree of service quality and continuity. Nevertheless, their faults represent one of the main causes of customer's unavailability. At the moment, a wide range of determinist criteria in the improvement of systems reliability based on past behavior are used, but they do not respond to the stochastic nature of system behavior, and are applied without an adequate balance between reliability and economy. In order to obtain this balance a minimum cost planning methodology that considers the predictive analysis of different investment alternatives in addition to the past behavior of the system is required, which guarantees that the economic resource available and limited will be used to gather the greater possible reliability degree. In this work this problem is approached with the fundamentals and methodologies needed to assess the design effects and operative criteria over the main reliability indexes used by the main utilities around the world, with emphasis on the need to optimize economical resources. The use of the system SynerGEETM, is investigated, probing it as a useful tool for the predictive reliability analysis. Due to the lack of experience that exists in Mexico with this type of analysis, distribution engineers has to become familiar with the concepts of the reliability engineering, their application to establish distribution systems models, and acquiring the ability to use the modern simulation tools, allowing them to evaluate the behavior of these systems with enough analytical rigor. In this sense a serial of well known study cases are presented to help them in this labor. [Spanish] Los sistemas de distribucion de energia electrica deben satisfacer la demanda de energia electrica de la forma mas economica posible, con un grado de calidad y continuidad aceptable. Sin embargo, sus fallas son una de las principales causas de indisponibilidad en

  16. Reliability and protection against failure in computer systems

    International Nuclear Information System (INIS)

    Daniels, B.K.

    1979-01-01

    Computers are being increasingly integrated into the control and safety systems of large and potentially hazardous industrial processes. This development introduces problems which are particular to computer systems and opens the way to new techniques of solving conventional reliability and availability problems. References to the developing fields of software reliability, human factors and software design are given, and these subjects are related, where possible, to the quantified assessment of reliability. Original material is presented in the areas of reliability growth and computer hardware failure data. The report draws on the experience of the National Centre of Systems Reliability in assessing the capability and reliability of computer systems both within the nuclear industry, and from the work carried out in other industries by the Systems Reliability Service. (author)

  17. An integrated reliability management system for nuclear power plants

    International Nuclear Information System (INIS)

    Kimura, T.; Shimokawa, H.; Matsushima, H.

    1998-01-01

    The responsibility in the nuclear field of the Government, utilities and manufactures has increased in the past years due to the need of stable operation and great reliability of nuclear power plants. The need to improve the reliability is not only for the new plants but also for those now running. So, several measures have been taken to improve reliability. In particular, the plant manufactures have developed a reliability management system for each phase (planning, construction, maintenance and operation) and these have been integrated as a unified system. This integrated reliability management system for nuclear power plants contains information about plant performance, failures and incidents which have occurred in the plants. (author)

  18. High Reliability Oscillators for Terahertz Systems Project

    Data.gov (United States)

    National Aeronautics and Space Administration — To develop reliable THz sources with high power and high DC-RF efficiency, Virginia Diodes, Inc. will develop a thorough understanding of the complex interactions...

  19. Performance and Risk Assessment of Soil-Structure Interaction Systems Based on Finite Element Reliability Methods

    Directory of Open Access Journals (Sweden)

    Quan Gu

    2014-01-01

    Full Text Available In the context of performance-based earthquake engineering, reliability method has been of significant importance in performance and risk assessment of structures or soil-structure interaction (SSI systems. The finite element (FE reliability method combines FE analysis with state-of-the-art methods in reliability analysis and has been employed increasingly to estimate the probability of occurrence of failure events corresponding to various hazard levels (e.g., earthquakes with various intensity. In this paper, crucial components for FE reliability analysis are reviewed and summarized. Furthermore, recent advances in both time invariant and time variant reliability analysis methods for realistic nonlinear SSI systems are presented and applied to a two-dimensional two story building on layered soil. Various time invariant reliability analysis methods are applied, including the first-order reliability method (FORM, importance sampling method, and orthogonal plane sampling (OPS method. For time variant reliability analysis, an upper bound of the failure probability is obtained from numerical integration of the mean outcrossing rate (MOCR. The MOCR is computed by using FORM analysis and OPS analysis. Results by different FE reliability methods are compared in terms of accuracy and computational cost. This paper provides valuable insights for reliability based probabilistic performance and risk assessment of SSI systems.

  20. Component reliability analysis for development of component reliability DB of Korean standard NPPs

    International Nuclear Information System (INIS)

    Choi, S. Y.; Han, S. H.; Kim, S. H.

    2002-01-01

    The reliability data of Korean NPP that reflects the plant specific characteristics is necessary for PSA and Risk Informed Application. We have performed a project to develop the component reliability DB and calculate the component reliability such as failure rate and unavailability. We have collected the component operation data and failure/repair data of Korean standard NPPs. We have analyzed failure data by developing a data analysis method which incorporates the domestic data situation. And then we have compared the reliability results with the generic data for the foreign NPPs

  1. Expert System for UNIX System Reliability and Availability Enhancement

    Science.gov (United States)

    Xu, Catherine Q.

    1993-01-01

    Highly reliable and available systems are critical to the airline industry. However, most off-the-shelf computer operating systems and hardware do not have built-in fault tolerant mechanisms, the UNIX workstation is one example. In this research effort, we have developed a rule-based Expert System (ES) to monitor, command, and control a UNIX workstation system with hot-standby redundancy. The ES on each workstation acts as an on-line system administrator to diagnose, report, correct, and prevent certain types of hardware and software failures. If a primary station is approaching failure, the ES coordinates the switch-over to a hot-standby secondary workstation. The goal is to discover and solve certain fatal problems early enough to prevent complete system failure from occurring and therefore to enhance system reliability and availability. Test results show that the ES can diagnose all targeted faulty scenarios and take desired actions in a consistent manner regardless of the sequence of the faults. The ES can perform designated system administration tasks about ten times faster than an experienced human operator. Compared with a single workstation system, our hot-standby redundancy system downtime is predicted to be reduced by more than 50 percent by using the ES to command and control the system.

  2. Creation and Reliability Analysis of Vehicle Dynamic Weighing Model

    Directory of Open Access Journals (Sweden)

    Zhi-Ling XU

    2014-08-01

    Full Text Available In this paper, it is modeled by using ADAMS to portable axle load meter of dynamic weighing system, controlling a single variable simulation weighing process, getting the simulation weighing data under the different speed and weight; simultaneously using portable weighing system with the same parameters to achieve the actual measurement, comparative analysis the simulation results under the same conditions, at 30 km/h or less, the simulation value and the measured value do not differ by more than 5 %, it is not only to verify the reliability of dynamic weighing model, but also to create possible for improving algorithm study efficiency by using dynamic weighing model simulation.

  3. Mathematical Methods in Survival Analysis, Reliability and Quality of Life

    CERN Document Server

    Huber, Catherine; Mesbah, Mounir

    2008-01-01

    Reliability and survival analysis are important applications of stochastic mathematics (probability, statistics and stochastic processes) that are usually covered separately in spite of the similarity of the involved mathematical theory. This title aims to redress this situation: it includes 21 chapters divided into four parts: Survival analysis, Reliability, Quality of life, and Related topics. Many of these chapters were presented at the European Seminar on Mathematical Methods for Survival Analysis, Reliability and Quality of Life in 2006.

  4. Reliability Estimation for Digital Instrument/Control System

    International Nuclear Information System (INIS)

    Yang, Yaguang; Sydnor, Russell

    2011-01-01

    Digital instrumentation and controls (DI and C) systems are widely adopted in various industries because of their flexibility and ability to implement various functions that can be used to automatically monitor, analyze, and control complicated systems. It is anticipated that the DI and C will replace the traditional analog instrumentation and controls (AI and C) systems in all future nuclear reactor designs. There is an increasing interest for reliability and risk analyses for safety critical DI and C systems in regulatory organizations, such as The United States Nuclear Regulatory Commission. Developing reliability models and reliability estimation methods for digital reactor control and protection systems will involve every part of the DI and C system, such as sensors, signal conditioning and processing components, transmission lines and digital communication systems, D/A and A/D converters, computer system, signal processing software, control and protection software, power supply system, and actuators. Some of these components are hardware, such as sensors and actuators, their failure mechanisms are well understood, and the traditional reliability model and estimation methods can be directly applied. But many of these components are firmware which has software embedded in the hardware, and software needs special consideration because its failure mechanism is unique, and the reliability estimation method for a software system will be different from the ones used for hardware systems. In this paper, we will propose a reliability estimation method for the entire DI and C system reliability using a recently developed software reliability estimation method and a traditional hardware reliability estimation method

  5. Reliability Analysis for Safety Grade PLC(POSAFE-Q)

    International Nuclear Information System (INIS)

    Choi, Kyung Chul; Song, Seung Whan; Park, Gang Min; Hwang, Sung Jae

    2012-01-01

    Safety Grade PLC(Programmable Logic Controller), POSAFE-Q, was developed recently in accordance with nuclear regulatory and requirements. In this paper, describe reliability analysis for digital safety grade PLC (especially POSAFE-Q). Reliability analysis scope is Prediction, Calculation of MTBF (Mean Time Between Failure), FMEA (Failure Mode Effect Analysis), PFD (Probability of Failure on Demand). (author)

  6. Reliability and Robustness Analysis of the Masinga Dam under Uncertainty

    Directory of Open Access Journals (Sweden)

    Hayden Postle-Floyd

    2017-02-01

    Full Text Available Kenya’s water abstraction must meet the projected growth in municipal and irrigation demand by the end of 2030 in order to achieve the country’s industrial and economic development plan. The Masinga dam, on the Tana River, is the key to meeting this goal to satisfy the growing demands whilst also continuing to provide hydroelectric power generation. This study quantitatively assesses the reliability and robustness of the Masinga dam system under uncertain future supply and demand using probabilistic climate and population projections, and examines how long-term planning may improve the longevity of the dam. River flow and demand projections are used alongside each other as inputs to the dam system simulation model linked to an optimisation engine to maximise water availability. Water availability after demand satisfaction is assessed for future years, and the projected reliability of the system is calculated for selected years. The analysis shows that maximising power generation on a short-term year-by-year basis achieves 80%, 50% and 1% reliability by 2020, 2025 and 2030 onwards, respectively. Longer term optimal planning, however, has increased system reliability to up to 95% in 2020, 80% in 2025, and more than 40% in 2030 onwards. In addition, increasing the capacity of the reservoir by around 25% can significantly improve the robustness of the system for all future time periods. This study provides a platform for analysing the implication of different planning and management of Masinga dam and suggests that careful consideration should be given to account for growing municipal needs and irrigation schemes in both the immediate and the associated Tana River basin.

  7. Probabilistic safety analysis and human reliability analysis. Proceedings. Working material

    International Nuclear Information System (INIS)

    1996-01-01

    An international meeting on Probabilistic Safety Assessment (PSA) and Human Reliability Analysis (HRA) was jointly organized by Electricite de France - Research and Development (EDF DER) and SRI International in co-ordination with the International Atomic Energy Agency. The meeting was held in Paris 21-23 November 1994. A group of international and French specialists in PSA and HRA participated at the meeting and discussed the state of the art and current trends in the following six topics: PSA Methodology; PSA Applications; From PSA to Dependability; Incident Analysis; Safety Indicators; Human Reliability. For each topic a background paper was prepared by EDF/DER and reviewed by the international group of specialists who attended the meeting. The results of this meeting provide a comprehensive overview of the most important questions related to the readiness of PSA for specific uses and areas where further research and development is required. Refs, figs, tabs

  8. System for the reliability analysis of the electric energy supply; Sistema para el analisis de confiabilidad del suministro de energia electrica

    Energy Technology Data Exchange (ETDEWEB)

    Perales, Favio; Martinez, Javier; Huesca, Francisco; Garcia, Norma; Nieva, Rolando [Instituto de Investigaciones Electricas, Cuernavaca (Mexico)

    1997-12-31

    A computer tool, developed for the reliability evaluation of the electric energy supply, considering the faults in the generation and transmission systems, is presented. The application of the tool in planning the expansion and operation of the electric systems, the methodology of the solution employed and the various functions it accounts for, are described. At the end some illustrative examples of its applications by means of the studies with a model of representative characteristics of the interconnected national system. [Espanol] Se presenta una herramienta computacional desarrollada para evaluar la confiabilidad del suministro de energia electrica, considerando las fallas en los sistemas de generacion y transmision. Se describen las aplicaciones de la herramienta en la planeacion de la expansion y de la operacion de sistemas electricos, la metodologia de solucion empleada y las diversas funciones con que cuenta. Al final se presentan algunos ejemplos ilustrativos de sus aplicaciones mediante estudios con un modelo de caracteristicas representativas del sistema interconectado nacional.

  9. A discussion of system reliability and the relative importance of pumps and valves to overall system availability

    International Nuclear Information System (INIS)

    Poole, A.B.

    1996-01-01

    An analysis was undertaken to establish preliminary trends for how component aging can effect failure rates for swing check valves, centrifugal pumps and motor operated valves. These failure rate trends were evaluated over time and linear aging rate models established. The failure rate models were then used with classic reliability theories to estimate reliability as a function of operating time. Reliability theory was also used to establish a simple system reliability model. Using the system model, the relative importance of pumps and valves to the overall system reliability were studied. Conclusions were established relative to overall system availability over time and the relative unavailabilities of the various components studied

  10. A discussion of system reliability and the relative importance of pumps and valves to overall system availability

    Energy Technology Data Exchange (ETDEWEB)

    Poole, A.B. [Oak Ridge National Lab., TN (United States)

    1996-12-01

    An analysis was undertaken to establish preliminary trends for how component aging can effect failure rates for swing check valves, centrifugal pumps and motor operated valves. These failure rate trends were evaluated over time and linear aging rate models established. The failure rate models were then used with classic reliability theories to estimate reliability as a function of operating time. Reliability theory was also used to establish a simple system reliability model. Using the system model, the relative importance of pumps and valves to the overall system reliability were studied. Conclusions were established relative to overall system availability over time and the relative unavailabilities of the various components studied.

  11. Bypassing BDD Construction for Reliability Analysis

    DEFF Research Database (Denmark)

    Williams, Poul Frederick; Nikolskaia, Macha; Rauzy, Antoine

    2000-01-01

    In this note, we propose a Boolean Expression Diagram (BED)-based algorithm to compute the minimal p-cuts of boolean reliability models such as fault trees. BEDs make it possible to bypass the Binary Decision Diagram (BDD) construction, which is the main cost of fault tree assessment.......In this note, we propose a Boolean Expression Diagram (BED)-based algorithm to compute the minimal p-cuts of boolean reliability models such as fault trees. BEDs make it possible to bypass the Binary Decision Diagram (BDD) construction, which is the main cost of fault tree assessment....

  12. Analysis of travel time reliability on Indiana interstates.

    Science.gov (United States)

    2009-09-15

    Travel-time reliability is a key performance measure in any transportation system. It is a : measure of quality of travel time experienced by transportation system users and reflects the efficiency : of the transportation system to serve citizens, bu...

  13. A methodology to incorporate organizational factors into human reliability analysis

    International Nuclear Information System (INIS)

    Li Pengcheng; Chen Guohua; Zhang Li; Xiao Dongsheng

    2010-01-01

    A new holistic methodology for Human Reliability Analysis (HRA) is proposed to model the effects of the organizational factors on the human reliability. Firstly, a conceptual framework is built, which is used to analyze the causal relationships between the organizational factors and human reliability. Then, the inference model for Human Reliability Analysis is built by combining the conceptual framework with Bayesian networks, which is used to execute the causal inference and diagnostic inference of human reliability. Finally, a case example is presented to demonstrate the specific application of the proposed methodology. The results show that the proposed methodology of combining the conceptual model with Bayesian Networks can not only easily model the causal relationship between organizational factors and human reliability, but in a given context, people can quantitatively measure the human operational reliability, and identify the most likely root causes or the prioritization of root causes caused human error. (authors)

  14. Mechanical reliability analysis of tubes intended for hydrocarbons

    Energy Technology Data Exchange (ETDEWEB)

    Nahal, Mourad; Khelif, Rabia [Badji Mokhtar University, Annaba (Algeria)

    2013-02-15

    Reliability analysis constitutes an essential phase in any study concerning reliability. Many industrialists evaluate and improve the reliability of their products during the development cycle - from design to startup (design, manufacture, and exploitation) - to develop their knowledge on cost/reliability ratio and to control sources of failure. In this study, we obtain results for hardness, tensile, and hydrostatic tests carried out on steel tubes for transporting hydrocarbons followed by statistical analysis. Results obtained allow us to conduct a reliability study based on resistance request. Thus, index of reliability is calculated and the importance of the variables related to the tube is presented. Reliability-based assessment of residual stress effects is applied to underground pipelines under a roadway, with and without active corrosion. Residual stress has been found to greatly increase probability of failure, especially in the early stages of pipe lifetime.

  15. Solid Rocket Booster Large Main and Drogue Parachute Reliability Analysis

    Science.gov (United States)

    Clifford, Courtenay B.; Hengel, John E.

    2009-01-01

    The parachutes on the Space Transportation System (STS) Solid Rocket Booster (SRB) are the means for decelerating the SRB and allowing it to impact the water at a nominal vertical velocity of 75 feet per second. Each SRB has one pilot, one drogue, and three main parachutes. About four minutes after SRB separation, the SRB nose cap is jettisoned, deploying the pilot parachute. The pilot chute then deploys the drogue parachute. The drogue chute provides initial deceleration and proper SRB orientation prior to frustum separation. At frustum separation, the drogue pulls the frustum from the SRB and allows the main parachutes that are mounted in the frustum to unpack and inflate. These chutes are retrieved, inspected, cleaned, repaired as needed, and returned to the flight inventory and reused. Over the course of the Shuttle Program, several improvements have been introduced to the SRB main parachutes. A major change was the replacement of the small (115 ft. diameter) main parachutes with the larger (136 ft. diameter) main parachutes. Other modifications were made to the main parachutes, main parachute support structure, and SRB frustum to eliminate failure mechanisms, improve damage tolerance, and improve deployment and inflation characteristics. This reliability analysis is limited to the examination of the SRB Large Main Parachute (LMP) and drogue parachute failure history to assess the reliability of these chutes. From the inventory analysis, 68 Large Main Parachutes were used in 651 deployments, and 7 chute failures occurred in the 651 deployments. Logistic regression was used to analyze the LMP failure history, and it showed that reliability growth has occurred over the period of use resulting in a current chute reliability of R = .9983. This result was then used to determine the reliability of the 3 LMPs on the SRB, when all must function. There are 29 drogue parachutes that were used in 244 deployments, and no in-flight failures have occurred. Since there are no

  16. Análise de confiabilidade do SICOGEA - sistema contábil gerencial e ambiental = Reliability analysis of SICOGEA - management and environmental accounting system

    Directory of Open Access Journals (Sweden)

    Bernadete Limongi

    2013-07-01

    Full Text Available A área ambiental tem sido discutida por vários profissionais, porém pouco ainda se relata sobre a Contabilidade Ambiental. Assim, a fim de criar um sistema que pudesse fornecer dados ambientais e contabilizá-los, optou-se pela realização do SICOGEA - Sistema Contábil-Gerencial Ambiental. Antes, porém, fazia-se necessário realizar uma análise de confiabilidade. Entrevistas semiestruturadas foram realizadas com profissionais de diversas áreas. Foram enviados, via e-mail, 55 instrumentos de análise, dos quais 53 retornaram, em 30 dias. Na análise empreendida verificou-se, como vantagem inicial da gestão ambiental, o envolvimento da sociedade, pois, conhecendo a realidade local, as possibilidades de solução para as questões ambientais tornam-se mais exequíveis. Percebeu-se uma relação entre as respostas aos questionários e a atividade profissional e acadêmica dos inquiridos: aqueles envolvidos mais diretamente com a área ambiental não demonstraram preocupação com lucratividade, mas aqueles voltados à área econômica entenderam que a gestão ambiental somente terá sucesso quando trouxer vantagem econômica. Percebeuse, pois, entre estes últimos, uma clara preocupação com a sobrevivência no mercado. E é nesse contexto que se insere o SICOGEA, uma nova alternativa de gestão e Contabilidade Ambiental, pois é um sistema que pode ajudar a elucidar a problemática ambiental e possibilitar o uso de tecnologias simples e eficientes, visando à preservação, ao mesmo tempo em que atende às exigências da legislação vigente. Environment has been discussed by many experts but there is not much reported on Environmental Accounting. Thus, in order to obtain a system which is capable of furnishing environmental data and registering them, SICOGEAwas created. It is an Environmental Managing and Accounting System. Before that a reliability test was applied. Semi-structured interviews with different professionals were undertaken

  17. Plant Reliability - an Integrated System for Management (PR-ISM)

    International Nuclear Information System (INIS)

    Aukeman, M.C.; Leininger, E.G.; Carr, P.

    1984-01-01

    The Toledo Edison Company, located in Toledo, Ohio, United States of America, recently implemented a comprehensive maintenance management information system for the Davis-Besse Nuclear Power Station. The system is called PR-ISM, meaning Plant Reliability - An Integrated System for Management. PR-ISM provides the tools needed by station management to effectively plan and control maintenance and other plant activities. The PR-ISM system as it exists today consists of four integrated computer applications: equipment data base maintenance, maintenance work order control, administrative activity tracking, and technical specification compliance. PR-ISM is designed as an integrated on-line system and incorporates strong human factors features. PR-ISM provides each responsible person information to do his job on a daily basis and to look ahead towards future events. It goes beyond 'after the fact' reporting. In this respect, PR-ISM is an 'interactive' control system which: captures work requirements and commitments as they are identified, provides accurate and up-to-date status immediately to those who need it, simplifies paperwork and reduces the associated time delays, provides the information base for work management and reliability analysis, and improves productivity by replacing clerical tasks and consolidating maintenance activities. The functional and technical features of PR-ISM, the experience of Toledo Edison during the first year of operation, and the factors which led to the success of the development project are highlighted. (author)

  18. RELIABILITY ANALYSIS OF URBAN RAINWATER HARVESTING FOR THREE TEXAS CITIES

    Directory of Open Access Journals (Sweden)

    Dustin Lawrence

    2016-01-01

    Full Text Available The purpose of this study was to inform decision makers at state and local levels, as well as property owners about the amount of water that can be supplied by rainwater harvesting systems in Texas so that it may be included in any future planning. Reliability of a rainwater tank is important because people want to know that a source of water can be depended on. Performance analyses were conducted on rainwater harvesting tanks for three Texas cities under different rainfall conditions and multiple scenarios to demonstrate the importance of optimizing rainwater tank design. Reliability curves were produced and reflect the percentage of days in a year that water can be supplied by a tank. Operational thresholds were reached in all scenarios and mark the point at which reliability increases by only 2% or less with an increase in tank size. A payback period analysis was conducted on tank sizes to estimate the amount of time it would take to recoup the cost of installing a rainwater harvesting system.

  19. Reliability Analysis of Existing Vertical Wall Breakwaters

    DEFF Research Database (Denmark)

    Burcharth, H. F.; Sørensen, John Dalsgaard

    1998-01-01

    Vertical wall breakwaters are used under quite different conditions where failure of the breakwater or a part of it will have very different consequences. Further a number of existing vertical wall breakwaters have been subjected to significant wave loads which have caused partial failures of the...... of the structures. The main objective of this paper is to describe how the reliability of existing breakwater structures within the expected remaining lifetime can be estimated taking into account the available information....

  20. Reliable data acquisition for inspection systems

    Science.gov (United States)

    Silva, V. P.; Silva, D. S.; Boccardo, D. R.; Machado, R. C. S.; Carmo, L. F. R. C.

    2015-01-01

    In Brazil, the road transportation of dangerous goods is subject to regulatory control, which is conducted by Inmetro, the National Institute of Metrology, Quality and Technology. Currently, the process of monitoring such inspections is done manually, leaving the possibility of some inconsistencies: inspections held outside the authorized local inspection, incorrectly, incompletely, or even be held. Thus, in order to increase the reliability of such inspections, it is needed a closer monitoring by the regulatory agency. One approach towards that, is the implementation of an automated process in which evidences are collected in a reliable way during the inspections, enabling further analyses. This work employs security mechanisms on a portable device to ensure the confidence of the evidences collected during an inspection, paving the way for later more robust analyzes.