WorldWideScience

Sample records for operational reliability improvements

  1. Advanced solutions for operational reliability improvements

    Energy Technology Data Exchange (ETDEWEB)

    Holmberg, K [VTT Manufacturing Technology, Espoo (Finland)

    1998-12-31

    A great number of new technical tools are today developed for improved operational reliability of machines and industrial equipment. Examples of such techniques and tools recently developed at the Technical Research Centre of Finland (VTT) are: metallographic approach for steam-piping lifetime estimation, an expert system AURORA for corrosion prediction and material selection, an automatic image-processing-based on-line wear particle analysis system, microsensors for condition monitoring, a condition monitoring and expert system, CEPDIA, for the diagnosis of centrifugal pumps, a machine tool analysis and diagnostic expert system, non-leakage magnetic fluid seals with extended lifetime and diamond-like surface coatings on components with decreased friction and wear properties. A hyperbook-supported holistic approach to problem solving in maintenance and reliability engineering has been developed to help the user achieve a holistic understanding of the problem and its relationships, to navigate among the several technical tools and methods available, and to find those suitable for his application. (orig.)

  2. Advanced solutions for operational reliability improvements

    Energy Technology Data Exchange (ETDEWEB)

    Holmberg, K. [VTT Manufacturing Technology, Espoo (Finland)

    1997-12-31

    A great number of new technical tools are today developed for improved operational reliability of machines and industrial equipment. Examples of such techniques and tools recently developed at the Technical Research Centre of Finland (VTT) are: metallographic approach for steam-piping lifetime estimation, an expert system AURORA for corrosion prediction and material selection, an automatic image-processing-based on-line wear particle analysis system, microsensors for condition monitoring, a condition monitoring and expert system, CEPDIA, for the diagnosis of centrifugal pumps, a machine tool analysis and diagnostic expert system, non-leakage magnetic fluid seals with extended lifetime and diamond-like surface coatings on components with decreased friction and wear properties. A hyperbook-supported holistic approach to problem solving in maintenance and reliability engineering has been developed to help the user achieve a holistic understanding of the problem and its relationships, to navigate among the several technical tools and methods available, and to find those suitable for his application. (orig.)

  3. Improving inspection reliability through operator selection and training

    International Nuclear Information System (INIS)

    McGrath, Bernard; Carter, Luke

    2013-01-01

    A number of years ago the UK's Health and Safety Executive sponsored a series of three PANI projects investigating the application of manual ultrasonics, which endeavoured to establish the necessary steps that ensure a reliable inspection is performed. The results of the three projects were each reported separately on completion and also presented at number of international conferences. This paper summarises the results of these projects from the point of view of operator performance. The correlation of operator ultrasonic performance with results of aptitude tests is presented along with observations on the impact of training and qualifications of the operators. The results lead to conclusions on how the selection and training of operators could be modified to improve reliability of inspections.

  4. Improving Reliability and Operational Availability of Military Systems

    National Research Council Canada - National Science Library

    Koehn, Phillip

    2004-01-01

    ...: overhaul and prognostics asset management strategies. It is shown that the prognostics approach leads to improved operational availability by anticipating failure and reducing administrative and logistics delays...

  5. QA support for TFTR reliability improvement program in preparation for DT operation

    International Nuclear Information System (INIS)

    Parsells, R.F.; Howard, H.P.

    1987-01-01

    As TFTR approaches experiments in the Q=1 regime, machine reliability becomes a major variable in achieving experimental objectives. This paper describes the methods used to quantify current reliability levels, levels required for D-T operations, proposed methods for reliability growth and improvement, and tracking of reliability performance in that growth. Included in this scope are data collection techniques and short comings, bounding current reliability on the upper end, and requirements for D-T operations. Problem characterization through Pareto diagrams provides insight into recurrent failure modes and the use of Duane plots for charting of reliability changes both cumulative and instantaneous, is explained and demonstrated

  6. Improvement of the reliability graph with general gates to analyze the reliability of dynamic systems that have various operation modes

    Energy Technology Data Exchange (ETDEWEB)

    Shin, Seung Ki [Div. of Research Reactor System Design, Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); No, Young Gyu; Seong, Poong Hyun [Dept. of Nuclear and Quantum Engineering, Korea Advanced Institute of Science and Technology, Daejeon (Korea, Republic of)

    2016-04-15

    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.

  7. Improvement of the reliability graph with general gates to analyze the reliability of dynamic systems that have various operation modes

    International Nuclear Information System (INIS)

    Shin, Seung Ki; No, Young Gyu; Seong, Poong Hyun

    2016-01-01

    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

  8. Operational safety reliability research

    International Nuclear Information System (INIS)

    Hall, R.E.; Boccio, J.L.

    1986-01-01

    Operating reactor events such as the TMI accident and the Salem automatic-trip failures raised the concern that during a plant's operating lifetime the reliability of systems could degrade from the design level that was considered in the licensing process. To address this concern, NRC is sponsoring the Operational Safety Reliability Research project. The objectives of this project are to identify the essential tasks of a reliability program and to evaluate the effectiveness and attributes of such a reliability program applicable to maintaining an acceptable level of safety during the operating lifetime at the plant

  9. Utilizing clad piping to improve process plant piping integrity, reliability, and operations

    International Nuclear Information System (INIS)

    Chakravarti, B.

    1996-01-01

    During the past four years carbon steel piping clad with type 304L (UNS S30403) stainless steel has been used to solve the flow accelerated corrosion (FAC) problem in nuclear power plants with exceptional success. The product is designed to allow ''like for like'' replacement of damaged carbon steel components where the carbon steel remains the pressure boundary and type 304L (UNS S30403) stainless steel the corrosion allowance. More than 3000 feet of piping and 500 fittings in sizes from 6 to 36-in. NPS have been installed in the extraction steam and other lines of these power plants to improve reliability, eliminate inspection program, reduce O and M costs and provide operational benefits. This concept of utilizing clad piping in solving various corrosion problems in industrial and process plants by conservatively selecting a high alloy material as cladding can provide similar, significant benefits in controlling corrosion problems, minimizing maintenance cost, improving operation and reliability to control performance and risks in a highly cost effective manner. This paper will present various material combinations and applications that appear ideally suited for use of the clad piping components in process plants

  10. Virtualization of Legacy Instrumentation Control Computers for Improved Reliability, Operational Life, and Management.

    Science.gov (United States)

    Katz, Jonathan E

    2017-01-01

    Laboratories tend to be amenable environments for long-term reliable operation of scientific measurement equipment. Indeed, it is not uncommon to find equipment 5, 10, or even 20+ years old still being routinely used in labs. Unfortunately, the Achilles heel for many of these devices is the control/data acquisition computer. Often these computers run older operating systems (e.g., Windows XP) and, while they might only use standard network, USB or serial ports, they require proprietary software to be installed. Even if the original installation disks can be found, it is a burdensome process to reinstall and is fraught with "gotchas" that can derail the process-lost license keys, incompatible hardware, forgotten configuration settings, etc. If you have running legacy instrumentation, the computer is the ticking time bomb waiting to put a halt to your operation.In this chapter, I describe how to virtualize your currently running control computer. This virtualized computer "image" is easy to maintain, easy to back up and easy to redeploy. I have used this multiple times in my own lab to greatly improve the robustness of my legacy devices.After completing the steps in this chapter, you will have your original control computer as well as a virtual instance of that computer with all the software installed ready to control your hardware should your original computer ever be decommissioned.

  11. Inducement of Design Parameters for Reliability Improvement of Servo Actuator for Hydraulic Valve Operation

    Energy Technology Data Exchange (ETDEWEB)

    Sung, Baek Ju; Kim, Do Sik [Korea Institute of Machinery and Materials, Daejeon (Korea, Republic of)

    2014-05-15

    The precision hydraulic valve is widely used in various industrial field like aircraft, automobile, and general machinery. Servo actuator is the most important device for driving the precise hydraulic valve. The reliable operation of servo actuator effects on the overall hydraulic system. The performance of servo actuator relies on frequency response and step response according to arbitrary input signal. In this paper, we performed the analysis for the components of servo actuator to satisfy the reliable operation and response characteristics through the reliability analysis, and also induced the design parameters to realize the reliable operation and fast response characteristics of servo actuator for hydraulic valve operation through the empirical knowledge of experts and electromagnetic theories. We suggested the design equations to determine the values of design parameters of servo actuator as like bobbin size, length of yoke and plunger and turn number of coil, and verified the achieved design values through FEM analysis and performance tests using some prototypes of servo actuators adapted in hydraulic valve.

  12. Operating experience and reliability improvements on the 5 kW CW klystron at Jefferson Lab

    International Nuclear Information System (INIS)

    Nelson, R.; Holben, S.

    1997-01-01

    With substantial operating hours on the RF system, considerable information on reliability of the 5 kW CW klystrons has been obtained. High early failure rates led to examination of the operating conditions and failure modes. Internal ceramic contamination caused premature failure of gun potting material and ultimate tube demise through arcing or ceramic fracture. A planned course of reporting and reconditioning of approximately 300 klystrons, plus careful attention to operating conditions and periodic analysis of operational data, has substantially reduced the failure rate. It is anticipated that implementation of planned supplemental monitoring systems for the klystrons will allow most catastrophic failures to be avoided. By predicting end of life, tubes can be changed out before they fail, thus minimizing unplanned downtime. Initial tests have also been conducted on this same klystron operated at higher voltages with resultant higher output power. The outcome of these tests will provide information to be considered for future upgrades to the accelerator

  13. Improvement of the reliability and efficiency of the NPP operation by training high-skilled personnel

    International Nuclear Information System (INIS)

    Korolev, V.V.; Sereda, G.A.

    1981-01-01

    Nuclear power at the modern stage of development is characterized by utilization of large power commercial reactors high technical specifications and economic parameters of which can be provided only at high reliability of the equipment and high qualification of the personnel. Special educational institution - Institute of nuclear engineering is organized for education of the operation personnel of high qualification for modern NPPs. Discussed are some problems occurring in this connection [ru

  14. Improving Reliability of Service Operation Using FMEA Review and New Opportunity for Investigations

    Science.gov (United States)

    Sutrisno, Agung; Gunawan, Indra

    2016-01-01

    Despite its growing contribution to the global economy, investigation on the application status of service FMEA study to support realization of reliable service operation is very limited in literature. Motivated by such situation, the paper presented an initial survey on the status and research gaps in developing and applying FMEA in service sectors. Systematic preliminary survey using specific criteria are undertaken. Our study indicated that development and application of service FMEA are partially addressing the characteristics of service operations and it is still applied into the good deed and profit oriented operations. Opportunities for further investigation pertaining to advancement of its decision supporting tool for service risk appraisal, its modification to cope with sustainability related requirements and application of service FMEA in not for profit oriented operations are presented as new avenues for further investigation

  15. Improving Power Converter Reliability

    DEFF Research Database (Denmark)

    Ghimire, Pramod; de Vega, Angel Ruiz; Beczkowski, Szymon

    2014-01-01

    of a high-power IGBT module during converter operation, which may play a vital role in improving the reliability of the power converters. The measured voltage is used to estimate the module average junction temperature of the high and low-voltage side of a half-bridge IGBT separately in every fundamental......The real-time junction temperature monitoring of a high-power insulated-gate bipolar transistor (IGBT) module is important to increase the overall reliability of power converters for industrial applications. This article proposes a new method to measure the on-state collector?emitter voltage...... is measured in a wind power converter at a low fundamental frequency. To illustrate more, the test method as well as the performance of the measurement circuit are also presented. This measurement is also useful to indicate failure mechanisms such as bond wire lift-off and solder layer degradation...

  16. Nuclear power plant safety and reliability improvements derived from operational experience analysis

    International Nuclear Information System (INIS)

    Zebroski, E.L.; Rosen, S.L.

    1983-01-01

    The frequency and distribution of significant events at operating nuclear power plants can be used as one of several indices to obtain a preliminary indication of unit and/or utility performance in the development and implementation of improvements aimed at reducing the probability or consequences of troublesome events. Initial data of this type are presented along with qualifications on the validity of such indicators. Planned further steps to improve this as a performance indicator are noted

  17. Improving the Transmission System Reliability for the 154kV Radial Network Operation

    Energy Technology Data Exchange (ETDEWEB)

    Choo, Jin Boo; Yoo, Myeong Ho; Yoon, Young Beum; Kim, Tae Won [Korea Electric Power Research Institute, Taejon (Korea, Republic of); Lee, Gi Won; Chung, Beom Jin; Jung, Jung Won; Park, Kyu Hyun; Lee, Myung Hee; Kim, Hyun Jong; Kim, Chae Hee [KEYIN CO., (Korea, Republic of)

    1996-12-31

    Analyzing that 154kV radial network current ed operated, we developed Automatic Power Reconfiguration System(APRS) which restore blackout area. It consists of special data acquisition system(DAU) and central monitoring system for reason of protecting currently operating power system. In addition, it communicates using optical communication network for high speed data transmission and accuracy. An Accuracy of operation and stability of the developed system is tested using Real Time Digital Simulator in 3-bus equivalent model system. In An Outage case, our developed system can restore a blackout area in three second. An ability of the restoration of a blackout was verified by simulations. For the field test, the developed system was set up at SINCHON S/S, SESOMUN S/S, SINDANG S/S and MAJANG S/S governed by Seoul Power Transmission Center. If the system reliability is proved for a one year test in real power system, application of the system will be extended to the other substations.

  18. Improving machinery reliability

    CERN Document Server

    Bloch, Heinz P

    1998-01-01

    This totally revised, updated and expanded edition provides proven techniques and procedures that extend machinery life, reduce maintenance costs, and achieve optimum machinery reliability. This essential text clearly describes the reliability improvement and failure avoidance steps practiced by best-of-class process plants in the U.S. and Europe.

  19. Improvement of Steam Turbine Operational Performance and Reliability with using Modern Information Technologies

    Science.gov (United States)

    Brezgin, V. I.; Brodov, Yu M.; Kultishev, A. Yu

    2017-11-01

    The report presents improvement methods review in the fields of the steam turbine units design and operation based on modern information technologies application. In accordance with the life cycle methodology support, a conceptual model of the information support system during life cycle main stages (LC) of steam turbine unit is suggested. A classifying system, which ensures the creation of sustainable information links between the engineer team (manufacture’s plant) and customer organizations (power plants), is proposed. Within report, the principle of parameterization expansion beyond the geometric constructions at the design and improvement process of steam turbine unit equipment is proposed, studied and justified. The report presents the steam turbine unit equipment design methodology based on the brand new oil-cooler design system that have been developed and implemented by authors. This design system combines the construction subsystem, which is characterized by extensive usage of family tables and templates, and computation subsystem, which includes a methodology for the thermal-hydraulic zone-by-zone oil coolers design calculations. The report presents data about the developed software for operational monitoring, assessment of equipment parameters features as well as its implementation on five power plants.

  20. Improving Reliability of High Power Quasi-CW Laser Diode Arrays Operating in Long Pulse Mode

    Science.gov (United States)

    Amzajerdian, Farzin; Meadows, Byron L.; Barnes, Bruce W.; Lockard, George E.; Singh, Upendra N.; Kavaya, Michael J.; Baker, Nathaniel R.

    2006-01-01

    Operating high power laser diode arrays in long pulse regime of about 1 msec, which is required for pumping 2-micron thulium and holmium-based lasers, greatly limits their useful lifetime. This paper describes performance of laser diode arrays operating in long pulse mode and presents experimental data of the active region temperature and pulse-to-pulse thermal cycling that are the primary cause of their premature failure and rapid degradation. This paper will then offer a viable approach for determining the optimum design and operational parameters leading to the maximum attainable lifetime.

  1. Application of space and aviation technology to improve the safety and reliability of nuclear power plant operations. Final report

    International Nuclear Information System (INIS)

    1980-04-01

    This report investigates various technologies that have been developed and utilized by the aerospace community, particularly the National Aeronautics and Space Administration (NASA) and the aviation industry, that would appear to have some potential for contributing to improved operational safety and reliability at commercial nuclear power plants of the type being built and operated in the United States today. The main initiator for this study, as well as many others, was the accident at the Three Mile Island (TMI) nuclear power plant in March 1979. Transfer and application of technology developed by NASA, as well as other public and private institutions, may well help to decrease the likelihood of similar incidents in the future

  2. Improvement of Operational Reliability Resource for JSC “Beltransgaz” Main Pipelines

    Directory of Open Access Journals (Sweden)

    V. V. Mayorov

    2013-01-01

    Full Text Available  The paper considers prospects for modernization of the operating linear portion of JSC “Beltransgaz” gas transportation system, various methods and materials which are used while implementing  construction and installation works in the oil and gas sector. It has been shown that in the recent decade one of the most technically, technologically and economically efficient application of the material is double-composite polyurethane coating. The method for coating deposition has been tested and introduced by JSC “Beltransgaz” with significant economic efficiency.

  3. Preliminary report of a gas conditioner to improve operational reliability of cryotherapy in developing countries

    Directory of Open Access Journals (Sweden)

    Broekhuizen Fredrik

    2006-02-01

    Full Text Available Abstract Background Cryotherapy is a safe, affordable, and effective method of treatment for cervical intraepithelial neoplasia. In some low-resource settings, environmental conditions or qualities of the refrigerant gas can lead to blockage of cryotherapy equipment, terminating treatment. A prototype of a gas conditioner to prevent operational failure was designed, built, and field tested. Methods The prototype conditioner device consists of an expansion chamber that filters and dries the refrigerant gas. Users in Peru and Kenya reported on their experience with the prototype conditioner. In Ghana, simulated cryotherapy procedures were used to test the effects of the prototype conditioner, as well as the commonly used "cough technique." Results Anecdotal reports from field use of the device were favorable. During simulated cryotherapy, the prevalence of blockage during freezing were 0% (0/25 with the device alone, 23.3% (7/30 with the cough technique alone, 5.9% (1/17 with both, and 55.2% (16/29 with neither (Pearson's Chi square = 26.6, df = 3, p Conclusion This prototype design of a cryotherapy gas conditioner is a potential solution for low-resource settings that are experiencing cryotherapy device malfunction.

  4. 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

  5. Increase of hydroelectric power plant operation reliability

    International Nuclear Information System (INIS)

    Koshumbaev, M.B.

    2006-01-01

    The new design of the turbine of hydroelectric power plant (HPP) is executed in the form of a pipe with plates. Proposed solution allows increasing the hydroelectric power plant capacity at existing head and water flow. At that time the HPP turbine reliability is increase, its operation performances are improving. Design efficiency is effective mostly for small-scale and micro-HPP due to reliable operation, low-end technology, and harmless ecological application. (author)

  6. Operator reliability assessment system (OPERAS)

    International Nuclear Information System (INIS)

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

    1991-01-01

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

  7. 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

  8. Steam generator reliability improvement project

    International Nuclear Information System (INIS)

    Blomgren, J.C.; Green, S.J.

    1987-01-01

    Upon successful completion of its research and development technology transfer program, the Electric Power Research Institute's Steam Generator Owners Group (SGOG II) will disband in December 1986 and be replaced in January 1987 by a successor project, the Steam Generator Reliability Project (SGRP). The new project, funded in the EPRI base program, will continue the emphasis on reliability and life extension that was carried forward by SGOG II. The objectives of SGOG II have been met. Causes and remedies have been identified for tubing corrosion problems, such as stress corrosion cracking and pitting, and steam generator technology has been improved in areas such as tube wear prediction and nondestructive evaluation (NDE). These actions have led to improved reliability of steam generators. Now the owners want to continue with a centrally managed program that builds on what has been learned. The goal is to continue to improve steam generator reliability and solve small problems before they become large problems

  9. Steam generator reliability improvement project

    International Nuclear Information System (INIS)

    Blomgren, J.C.; Green, S.J.

    1987-01-01

    Upon successful completion of its research and development technology transfer program, the Electric Power Research Institute's (EPRI's) Steam Generator Owners Group (SGOG II) will disband in December 1986, and be replaced in January 1987, by a successor project, the Steam Generator Reliability Project (SGRP). The new project, funded in the EPRI base program, will continue to emphasize reliability and life extension, which were carried forward by SGOG II. The objectives of SGOG II have been met. Causes and remedies have been identified for tubing corrosion problems such as stress corrosion cracking and pitting, and steam generator technology has been improved in areas such as tube wear prediction and nondestructive evaluation. These actions have led to improved reliability of steam generators. Now the owners want to continue with a centrally managed program that builds on what has been learned. The goal is to continue to improve steam generator reliability and to solve small problems before they become large problems

  10. 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

  11. Teaming up to improve reliability

    International Nuclear Information System (INIS)

    Malone, E.A.; Ayres, D.J.; Lear, R.C. van

    1989-01-01

    Responding to increasingly stringent regulatory requirements, Babcock and Wilcox has teamed up with three specialist companies to provide services for nuclear utilities aiming to improve the performance of their valves and actuators. The services, which are outlined here, include inspection, repair, overhaul and valve and actuator reliability programmes. (author)

  12. Improving the safety and reliability of Monju

    International Nuclear Information System (INIS)

    Itou, Kazumoto; Maeda, Hiroshi; Moriyama, Masatoshi

    1998-01-01

    Comprehensive safety review has been performed at Monju to determine why the Monju secondary sodium leakage accident occurred. We investigated how to improve the situation based on the results of the safety review. The safety review focused on five aspects of whether the facilities for dealing with the sodium leakage accident were adequate: the reliability of the detection method, the reliability of the method for preventing the spread of the sodium leakage accident, whether the documented operating procedures are adequate, whether the quality assurance system, program, and actions were properly performed and so on. As a result, we established for Monju a better method of dealing with sodium leakage accidents, rapid detection of sodium leakage, improvement of sodium drain facilities, and way to reduce damage to Monju systems after an accident. We also improve the operation procedures and quality assurance actions to increase the safety and reliability of Monju. (author)

  13. 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.

  14. 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

  15. Operational human performance reliability assessment (OHPRA)

    International Nuclear Information System (INIS)

    Haas, P.M.; Swanson, P.J.; Connelly, E.M.

    1993-01-01

    Operational Human Performance Reliability Assessment (OHPRA) is an approach for assessing human performance that is being developed in response to demands from modern process industries for practical and effective tools to assess and improve human performance, and therefore overall system performance and safety. The single most distinguishing feature of the approach is that is defines human performance in open-quotes operationalclose quotes terms. OHPRA is focused not on generation of human error probabilities, but on practical analysis of human performance to aid management in (1) identifying open-quotes fixableclose quotes problems and (2) providing input on the importance and nature of potential improvements. Development of the model in progress uses a unique approach for eliciting expert strategies for assessing performance. A PC-based model incorporating this expertise is planned. A preliminary version of the approach has already been used successfully to identify practical human performance problems in reactor and chemical process plant operations

  16. Enhancing operability and reliability through configuration management

    International Nuclear Information System (INIS)

    Hancock, L.R.

    1993-01-01

    This paper describes the evolution of plant design control techniques from the early 1970's to today's operating environment that demands accurate, up-to-date design data. This evolution of design control is responsible for the increasingly troublesome scenario of design data being very difficult to locate and when found, its credibility is questioned. The design information could be suspect because there are discrepancies between two or more source documents or there is a difference between the design documents and the physical configuration of the plant. This paper discusses the impact these design control problems are having on plant operations and presents common sense solutions for improving configuration management techniques to ultimately enhance operability and reliability

  17. Regional transportation operations collaboration and coordination : a primer for working together to improve transportation safety, reliability, and security

    Science.gov (United States)

    2002-01-01

    This primer was written for transportation professionals and public safety officials from cities, counties, and States who are responsible for day-to-day management and operations within a metropolitan region. It is intended to help agencies and orga...

  18. Improved reliability of power modules

    DEFF Research Database (Denmark)

    Baker, Nick; Liserre, Marco; Dupont, Laurent

    2014-01-01

    Power electronic systems play an increasingly important role in providing high-efficiency power conversion for adjustable-speed drives, power-quality correction, renewable-energy systems, energy-storage systems, and electric vehicles. However, they are often presented with demanding operating...... environments that challenge the reliability aspects of power electronic techniques. For example, increasingly thermally stressful environments are seen in applications such as electric vehicles, where ambient temperatures under the hood exceed 150 °C, while some wind turbine applications can place large...

  19. ARCHITECTURE AND RELIABILITY OF OPERATING SYSTEMS

    Directory of Open Access Journals (Sweden)

    Stanislav V. Nazarov

    2018-03-01

    Full Text Available Progress in the production technology of microprocessors significantly increased reliability and performance of the computer systems hardware. It cannot be told about the corresponding characteristics of the software and its basis – the operating system (OS. Some achievements of program engineering are more modest in this field. Both directions of OS improvement (increasing of productivity and reliability are connected with the development of effective structures of these systems. OS functional complexity leads to the multiplicity of the structure, which is further enhanced by the specialization of the operating system depending on scope of computer system (complex scientific calculations, real time, information retrieval systems, systems of the automated and automatic control, etc. The functional complexity of the OS leads to the complexity of its architecture, which is further enhanced by the specialization of the operating system, depending on the computer system application area (complex scientific calculations, real-time, information retrieval systems, automated and automatic control systems, etc.. That fact led to variety of modern OS. It is possible to estimate reliability of different OS structures only as results of long-term field experiment or simulation modeling. However it is most often unacceptable because of time and funds expenses for carrying out such research. This survey attempts to evaluate the reliability of two main OS architectures: large multi-layered modular core and a multiserver (client-server system. Represented by continuous Markov chains which are explored in the stationary mode on the basis of transition from systems of the differential equations of Kolmogorov to system of the linear algebraic equations, models of these systems are developed.

  20. Operator reliability analysis during NPP small break LOCA

    International Nuclear Information System (INIS)

    Zhang Jiong; Chen Shenglin

    1990-01-01

    To assess the human factor characteristic of a NPP main control room (MCR) design, the MCR operator reliability during a small break LOCA is analyzed, and some approaches for improving the MCR operator reliability are proposed based on the analyzing results

  1. A reliability program approach to operational safety

    International Nuclear Information System (INIS)

    Mueller, C.J.; Bezella, W.A.

    1985-01-01

    A Reliability Program (RP) model based on proven reliability techniques is being formulated for potential application in the nuclear power industry. Methods employed under NASA and military direction, commercial airline and related FAA programs were surveyed and a review of current nuclear risk-dominant issues conducted. The need for a reliability approach to address dependent system failures, operating and emergency procedures and human performance, and develop a plant-specific performance data base for safety decision making is demonstrated. Current research has concentrated on developing a Reliability Program approach for the operating phase of a nuclear plant's lifecycle. The approach incorporates performance monitoring and evaluation activities with dedicated tasks that integrate these activities with operation, surveillance, and maintenance of the plant. The detection, root-cause evaluation and before-the-fact correction of incipient or actual systems failures as a mechanism for maintaining plant safety is a major objective of the Reliability Program. (orig./HP)

  2. Product reliability and the reliability of its emanating operational processes.

    NARCIS (Netherlands)

    Sonnemans, P.J.M.; Geudens, W.H.J.M.

    1999-01-01

    This paper addresses the problem of proper reliability management in business operations today, facing increasing demands on essential business drivers such as time to market, quality and financial profit. In this paper a general method is described of how to achieve product quality in a highly

  3. SLAC modulator system improvements and reliability results

    International Nuclear Information System (INIS)

    Donaldson, A.R.

    1998-06-01

    In 1995, an improvement project was completed on the 244 klystron modulators in the linear accelerator. The modulator system has been previously described. This article offers project details and their resulting effect on modulator and component reliability. Prior to the project, the authors had collected four operating cycles (1991 through 1995) of MTTF data. In this discussion, the '91 data will be excluded since the modulators operated at 60 Hz. The five periods following the '91 run were reviewed due to the common repetition rate at 120 Hz

  4. Training benefits of research on operator reliability

    International Nuclear Information System (INIS)

    Worledge, D.H.

    1989-01-01

    The purpose of the EPRI Operator Reliability Experiments (ORE) Program is to collect data for use in reliability and safety studies of nuclear power plant operation which more realistically take credit for operator performance in preventing core damage. The three objectives in fulfilling this purpose are: to obtain quantitative/qualitative performance data on operating crew responses in the control room for potential accident sequences by using plant simulators; to test the human cognitive reliability (HCR) correlation; and to develop a data collection analysis procedure. This paper discusses the background to this program, data collection and analysis, and the results of quantitative/qualitative insights stemming from initial work. Special attention is paid to how this program impacts upon simulator use and assessment of simulator fidelity. Attention is also paid to the use of data collection procedures to assist training departments in assessing the quality of their training programs

  5. The fair value of operational reliability

    International Nuclear Information System (INIS)

    Patino-Echeverri, Dalia; Morel, Benoit

    2005-01-01

    Information about the uncertainties that surround the operation of the power system can be used to enlighten the debate of how much reliability should be pursued and how resources should be allocated to pursue it. In this paper we present a method to determine the value of having flexible generators to react to load fluctuations. This value can be seen as the value of hedging against the uncertainty on the load due to the volatility of the demand and the possibility of congestion. Because having this flexibility can be related to a financial option, we will use an extension of options theory and in particular the risk-neutral valuation method, to find a risk neutral quantification of its value. We illustrate our point valuing the flexibility that leads to ''operational reliability'' in the PJM market. Our formula for that value is what we call ''the fair value'' of operational reliability. (Author)

  6. Piping reliability improvement through passive seismic supports

    International Nuclear Information System (INIS)

    Baltus, R.; Rubbers, A.

    1999-01-01

    The nuclear plants designed in the 1970's were equipped with large quantities of snubbers in auxiliary piping systems. The experience revealed a poor performance of snubbers during periodic inspection, while non-nuclear facility piping survived through strong earthquakes. Consequently, seismic design rules evolved towards more realistic criteria and passive dynamic supports were developed to reduce snubber quantities. These solutions improve the pipe reliability during normal operation while reducing the radiation exposure in a sample line is presented with the impact on pipe stresses compared to the results obtained with passive supports named Limit Stops. (author)

  7. Improvement of reliability of heater and condenser

    International Nuclear Information System (INIS)

    Yamagishi, Hiroki

    1988-01-01

    Recently, the diversification of the operation modes of power plants has advanced as well as daily start and stop and weekly start and stop operations, as the result, the needs for the reliability improvement of various heat exchangers around steam turbines heighten. In newly constructed plants, the design to meet this demand is carried out, but also in existing platns, the application of the latest technology is investigated. As for the reliability of condensers, aluminum brass cooling tubes have been used by doing the optimal maintenance and taking the measures against deposit attack. In the case of requiring high reliability, the examples of adopting titanium cooling tubes increased. The technology of titanium tube condensers, completely assembled condensers, the replacement of existing brass tubes with titanium tubes and so on are discussed. In the case of feed heaters, the deterioration phenomena due to the lapse of long years, such as the attack of steel tube inlet, the drain attack on the external surfaces of steel tubes, the ammonia attack of aluminum brass tubes and the adhesion of scale to heaters, are explained, and the countermeasures are shown. (Kako, I.)

  8. Improving operating room safety

    Directory of Open Access Journals (Sweden)

    Garrett Jill

    2009-11-01

    Full Text Available Abstract Despite the introduction of the Universal Protocol, patient safety in surgery remains a daily challenge in the operating room. This present study describes one community health system's efforts to improve operating room safety through human factors training and ultimately the development of a surgical checklist. Using a combination of formal training, local studies documenting operating room safety issues and peer to peer mentoring we were able to substantially change the culture of our operating room. Our efforts have prepared us for successfully implementing a standardized checklist to improve operating room safety throughout our entire system. Based on these findings we recommend a multimodal approach to improving operating room safety.

  9. Reliability of operating WWER monitoring systems

    International Nuclear Information System (INIS)

    Yastrebenetsky, M.A.; Goldrin, V.M.; Garagulya, A.V.

    1996-01-01

    The elaboration of WWER monitoring systems reliability measures is described in this paper. The evaluation is based on the statistical data about failures what have collected at the Ukrainian operating nuclear power plants (NPP). The main attention is devoted to radiation safety monitoring system and unit information computer system, what collects information from different sensors and system of the unit. Reliability measures were used for decision the problems, connected with life extension of the instruments, and for other purposes. (author). 6 refs, 6 figs

  10. Reliability of operating WWER monitoring systems

    Energy Technology Data Exchange (ETDEWEB)

    Yastrebenetsky, M A; Goldrin, V M; Garagulya, A V [Ukrainian State Scientific Technical Center of Nuclear and Radiation Safety, Kharkov (Ukraine). Instrumentation and Control Systems Dept.

    1997-12-31

    The elaboration of WWER monitoring systems reliability measures is described in this paper. The evaluation is based on the statistical data about failures what have collected at the Ukrainian operating nuclear power plants (NPP). The main attention is devoted to radiation safety monitoring system and unit information computer system, what collects information from different sensors and system of the unit. Reliability measures were used for decision the problems, connected with life extension of the instruments, and for other purposes. (author). 6 refs, 6 figs.

  11. 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)

  12. Relativity evaluation of reliability on operation in nuclear power plant

    International Nuclear Information System (INIS)

    Inata, Takashi

    1987-01-01

    The report presents a quantitative method for evaluating the reliability of operations conducted in nuclear power plants. The quantitative reliability evaluation method is based on the 'detailed block diagram analysis (De-BDA)'. All units of a series of operations are separately displayed for each block and combined sequentially. Then, calculation is performed to evaluate the reliability. Basically, De-BDA calculation is made for pairs of operation labels, which are connected in parallel or in series at different subordination levels. The applicability of the De-BDA method is demonstrated by carrying out calculation for three model cases: operations in the event of malfunction of the control valve in the main water supply system for PWR, switching from an electrically-operated water supply pump to a turbin-operated water supply pump, and isolation and water removal operation for a low-pressure condensate pump. It is shown that the relative importance of each unit of a series of operations can be evaluated, making it possible to extract those units of greater importance, and that the priority among the factors which affect the reliability of operations can be determined. Results of the De-BDA calculation can serve to find important points to be considered in developing an operation manual, conducting education and training, and improving facilities. (Nogami, K.)

  13. Operational and reliability experience with reactor instrumentation

    International Nuclear Information System (INIS)

    Dixon, F.; Gow, R.S.

    1978-01-01

    In the last 15 years the CEGB has experienced progressive plant development, integration and changes in operating regime through nine nuclear (gas-cooled reactor) power stations with corresponding instrumentation advances leading towards more refined centralized control. Operation and reliability experience with reactor instrumentation is reported in this paper with reference to the progressive changes related to the early magnox, late magnox and AGR periods. Data on instrumentation reliability in terms of reactor forced outages are presented and show that the instrumentation contributions to loss of generating plant availability are small. Reactor safety circuits, neutron flux and temperature measurements, gas analysis and vibration monitoring are discussed. In reviewing the reactor instrumentation the emphasis is on reporting recent experience, particularly on AGR equipment, but overall performance and changes to magnox equipment are included so that some appreciation can be obtained of instrumentation requirements with respect to plant lifetimes. (author)

  14. 76 FR 58101 - Electric Reliability Organization Interpretation of Transmission Operations Reliability Standard

    Science.gov (United States)

    2011-09-20

    ....C. Cir. 2009). \\4\\ Mandatory Reliability Standards for the Bulk-Power System, Order No. 693, FERC... for maintaining real and reactive power balance. \\14\\ Electric Reliability Organization Interpretation...; Order No. 753] Electric Reliability Organization Interpretation of Transmission Operations Reliability...

  15. Impact of staffing parameters on operational reliability

    International Nuclear Information System (INIS)

    Hahn, H.A.; Houghton, F.K.

    1993-01-01

    This paper reports on a project related to human resource management of the Department of Energy's (DOE's) High-Level Waste (HLW) Tank program. Safety and reliability of waste tank operations is impacted by several issues, including not only the design of the tanks themselves, but also how operations and operational personnel are managed. As demonstrated by management assessments performed by the Tiger Teams, DOE believes that the effective use of human resources impacts environment safety, and health concerns. For the of the current paper, human resource management activities are identified as ''Staffing'' and include the of developing the functional responsibilities and qualifications of technical and administrative personnel. This paper discusses the importance of staff plans and management in the overall view of safety and reliability. The work activities and procedures associated with the project, a review of the results of these activities, including a summary of the literature and a preliminary analysis of the data. We conclude that although identification of staffing issues and the development of staffing plans contributes to the overall reliability and safety of the HLW tanks, the relationship is not well understood and is in need of further development

  16. The fair value of operational reliability

    Energy Technology Data Exchange (ETDEWEB)

    Patino-Echeverri, Dalia; Morel, Benoit

    2005-12-15

    Information about the uncertainties that surround the operation of the power system can be used to enlighten the debate of how much reliability should be pursued and how resources should be allocated to pursue it. In this paper we present a method to determine the value of having flexible generators to react to load fluctuations. This value can be seen as the value of hedging against the uncertainty on the load due to the volatility of the demand and the possibility of congestion. Because having this flexibility can be related to a financial option, we will use an extension of options theory and in particular the risk-neutral valuation method, to find a risk neutral quantification of its value. We illustrate our point valuing the flexibility that leads to ''operational reliability'' in the PJM market. Our formula for that value is what we call ''the fair value'' of operational reliability. (Author)

  17. Impact of staffing parameters on operational reliability

    International Nuclear Information System (INIS)

    Hahn, H.A.; Houghton, F.K.

    1993-01-01

    This paper reports on a project related to human resource management of the Department of Energy (DOEs) High-Level Waste (HLW) Tank program. Safety and reliability of waste tank operations is impacted by several issues, including not only the design of the tanks themselves, but also how operations and operational personnel are managed. As demonstrated by management assessments performed by the Tiger Teams, DOE believes that the effective use of human resources impacts environment, safety, and health concerns. For the purposes of the current paper, human resource management activities are identified as 'Staffing' and include the process of developing the functional responsibilities and qualifications of technical and administrative personnel. This paper discusses the importance of staff plans and management in the overall view of safety and reliability, the work activities and procedures associated with the project, a review of the results of these activities, including a summary of the literature and a preliminary analysis of the data. We conclude that, although identification of staffing issues and the development of staffing plans contributes to the overall reliability and safety of the HLW tanks, the relationship is not well understood and is in need of further development

  18. Improvement of the electromagnetic situation in networks of operational current at nuclear power plant for the purpose of ensuring reliability of monitoring systems, control, RPA and communications, realized on the basis of digital equipment

    International Nuclear Information System (INIS)

    Fomenko, O.V.; Moloshnaya, E.S.; Ul'yanova, Yu.E.

    2014-01-01

    The authors propose the technique of designing a portable grounding contour for protection and control systems, relay protection and automation (RPA) systems made on the basis of digital equipment in networks of an operational direct current to increase the reliability of their functioning under the conditions of influence of strong hindrances and improvement of an electromagnetic environment [ru

  19. Reliability assurance program for operational emergency ac power system

    International Nuclear Information System (INIS)

    Heineman, J.B.; Ragland, W.A.; Mueller, C.J.

    1985-01-01

    A comprehensive review of emergency ac power systems in nuclear generating plants (the vast majority of these plants contain redundant diesel generator systems) delineates several operational areas that can be improved by instituting a reliability assurance program (RAP), which initially upgrades the diesel generator performance and provides for ongoing monitoring and maintenance based upon alert levels

  20. Prediction of software operational reliability using testing environment factors

    International Nuclear Information System (INIS)

    Jung, Hoan Sung; Seong, Poong Hyun

    1995-01-01

    A number of software reliability models have been developed to estimate and to predict software reliability. However, there are no established standard models to quantify software reliability. Most models estimate the quality of software in reliability figures such as remaining faults, failure rate, or mean time to next failure at the testing phase, and they consider them ultimate indicators of software reliability. Experience shows that there is a large gap between predicted reliability during development and reliability measured during operation, which means that predicted reliability, or so-called test reliability, is not operational reliability. Customers prefer operational reliability to test reliability. In this study, we propose a method that predicts operational reliability rather than test reliability by introducing the testing environment factor that quantifies the changes in environments

  1. Simulator experiments on operator reliability and training effectiveness

    International Nuclear Information System (INIS)

    Singh, A. Spurgin, A.J.

    1990-01-01

    This paper discusses some aspects of the Operator Reliability Experiments project sponsored by Electric Power Research Institute. The paper deals with modifications to the HCR correlation which have resulted from the study of operators in responding to nuclear accident scenarios using emergency procedures. The interpretation of time response data and how insights in crew performance can lead to improvements in not only crew performance but also in training effectiveness are discussed

  2. 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...

  3. Reliability-How to Quantify and Improve?

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 5; Issue 5. Reliability - How to Quantify and Improve? - Improving the Health of Products. N K Srinivasan. General Article Volume 5 Issue 5 May 2000 pp 55-63. Fulltext. Click here to view fulltext PDF. Permanent link:

  4. Improving Reliability of a Residency Interview Process

    Science.gov (United States)

    Serres, Michelle L.; Gundrum, Todd E.

    2013-01-01

    Objective. To improve the reliability and discrimination of a pharmacy resident interview evaluation form, and thereby improve the reliability of the interview process. Methods. In phase 1 of the study, authors used a Many-Facet Rasch Measurement model to optimize an existing evaluation form for reliability and discrimination. In phase 2, interviewer pairs used the modified evaluation form within 4 separate interview stations. In phase 3, 8 interviewers individually-evaluated each candidate in one-on-one interviews. Results. In phase 1, the evaluation form had a reliability of 0.98 with person separation of 6.56; reproducibly, the form separated applicants into 6 distinct groups. Using that form in phase 2 and 3, our largest variation source was candidates, while content specificity was the next largest variation source. The phase 2 g-coefficient was 0.787, while confirmatory phase 3 was 0.922. Process reliability improved with more stations despite fewer interviewers per station—impact of content specificity was greatly reduced with more interview stations. Conclusion. A more reliable, discriminating evaluation form was developed to evaluate candidates during resident interviews, and a process was designed that reduced the impact from content specificity. PMID:24159209

  5. Improving reliability of a residency interview process.

    Science.gov (United States)

    Peeters, Michael J; Serres, Michelle L; Gundrum, Todd E

    2013-10-14

    To improve the reliability and discrimination of a pharmacy resident interview evaluation form, and thereby improve the reliability of the interview process. In phase 1 of the study, authors used a Many-Facet Rasch Measurement model to optimize an existing evaluation form for reliability and discrimination. In phase 2, interviewer pairs used the modified evaluation form within 4 separate interview stations. In phase 3, 8 interviewers individually-evaluated each candidate in one-on-one interviews. In phase 1, the evaluation form had a reliability of 0.98 with person separation of 6.56; reproducibly, the form separated applicants into 6 distinct groups. Using that form in phase 2 and 3, our largest variation source was candidates, while content specificity was the next largest variation source. The phase 2 g-coefficient was 0.787, while confirmatory phase 3 was 0.922. Process reliability improved with more stations despite fewer interviewers per station-impact of content specificity was greatly reduced with more interview stations. A more reliable, discriminating evaluation form was developed to evaluate candidates during resident interviews, and a process was designed that reduced the impact from content specificity.

  6. Reliability Considerations for the Operation of Large Accelerator User Facilities

    CERN Document Server

    Willeke, F.J.

    2016-01-01

    The lecture provides an overview of considerations relevant for achieving highly reliable operation of accelerator based user facilities. The article starts with an overview of statistical reliability formalism which is followed by high reliability design considerations with examples. The article closes with operational aspects of high reliability such as preventive maintenance and spares inventory.

  7. Prediction of software operational reliability using testing environment factors

    International Nuclear Information System (INIS)

    Jung, Hoan Sung; Seong, Poong Hyun

    1995-01-01

    For many years, many researches have focused on the quantification of software reliability and there are many models developed to quantify software reliability. Most software reliability models estimate the reliability with the failure data collected during the test assuming that the test environments well represent the operation profile. The experiences show that the operational reliability is higher than the test reliability User's interest is on the operational reliability rather than on the test reliability, however. With the assumption that the difference in reliability results from the change of environment, testing environment factors comprising the aging factor and the coverage factor are defined in this study to predict the ultimate operational reliability with the failure data. It is by incorporating test environments applied beyond the operational profile into testing environment factors. The application results are close to the actual data

  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. Status of an operating reliability program

    International Nuclear Information System (INIS)

    Johnson, R.A.

    1985-01-01

    This paper deals with productivity improvement programs (PIP) for nuclear generating plants. The PIP was implemented in 1979 as a joint effort between Commonwealth Edison's (CECo's) operating nuclear stations and the Station Nuclear Engineering Department. Goals were set to reduce nonproductivity by 10% over a 5 year period. This goal was accomplished December 31, 1983. Topics of discussion are program method, problem analysis and resolution, program results, program improvements, and proposed additions to the PIP. The program is providing CECo with greater electrical generating productivity

  10. 78 FR 73112 - Monitoring System Conditions-Transmission Operations Reliability Standards; Interconnection...

    Science.gov (United States)

    2013-12-05

    ...\\ \\8\\ Mandatory Reliability Standards for the Bulk-Power System, Order No. 693, 72 FR 16416 (Apr. 4... operators and reliability coordinators to ``plan and operate the interconnected Bulk Electric System in a... mandated in the currently- effective standards, thereby improving reliability of the bulk power system...

  11. Reliability studies of high operating temperature MCT photoconductor detectors

    Science.gov (United States)

    Wang, Wei; Xu, Jintong; Zhang, Yan; Li, Xiangyang

    2010-10-01

    This paper concerns HgCdTe (MCT) infrared photoconductor detectors with high operating temperature. The near room temperature operation of detectors have advantages of light weight, less cost and convenient usage. Their performances are modest and they suffer from reliable problems. These detectors face with stability of the package, chip bonding area and passivation layers. It's important to evaluate and improve the reliability of such detectors. Defective detectors were studied with SEM(Scanning electron microscope) and microscopy. Statistically significant differences were observed between the influence of operating temperature and the influence of humidity. It was also found that humility has statistically significant influence upon the stability of the chip bonding and passivation layers, and the amount of humility isn't strongly correlated to the damage on the surface. Considering about the commonly found failures modes in detectors, special test structures were designed to improve the reliability of detectors. An accelerated life test was also implemented to estimate the lifetime of the high operating temperature MCT photoconductor detectors.

  12. Technology and equipment to improve reliability of pipeline transport

    Science.gov (United States)

    Suleimanov, D. F.; Shulayev, N. S.; Bondar, K. E.; Laponov, S. V.; Uzinger, A. A.

    2017-10-01

    The article is dedicated to development of technology and hardware design of method pipeline transport reliability improving by improving the isolated coating properties modified by microwave radiation. The article describes the technology of the modification process of the coating and instrumentation production, which allows improving operational properties not only in stationary conditions in the manufacture of the insulation coating, but also during its replacement in the field.

  13. Improvement of the reliability on nondestructive inspection

    International Nuclear Information System (INIS)

    Song, Sung Jin; Kim, Young H.; Lee, Hyang Beom; Shin, Young Kil; Jung, Hyun Jo; Park, Ik Keun; Park, Eun Soo

    2002-03-01

    Retaining reliabilities of nondestructive testing is essential for the life-time maintenance of Nuclear Power Plant. The nondestructive testing methods which are frequently used in the Nuclear Power Plant are eddy current testing for the inspection of steam generator tubes and ultrasonic testing for the inspection of weldments. In order to improve reliabilities of ultrasonic testing and eddy current testing, the subjects carried out in this study are as follows : development of BEM analysis technique for ECT of SG tube, development of neural network technique for the intelligent analysis of ECT flaw signals of SG tubes, development of RFECT technology for the inspection of SG tube, FEM analysis of ultrasonic scattering field, evaluation of statistical reliability of PD-RR test of ultrasonic testing and development of multi-Gaussian beam modeling technique to predict accurate signal of signal beam ultrasonic testing with the efficiency in calculation time

  14. Improvement of the reliability on nondestructive inspection

    Energy Technology Data Exchange (ETDEWEB)

    Song, Sung Jin; Kim, Young H. [Sungkyunkwan Univ., Suwon (Korea, Republic of); Lee, Hyang Beom [Soongsil Univ., Seoul (Korea, Republic of); Shin, Young Kil [Kunsan National Univ., Gunsan (Korea, Republic of); Jung, Hyun Jo [Wonkwang Univ., Iksan (Korea, Republic of); Park, Ik Keun; Park, Eun Soo [Seoul Nationl Univ., Seoul (Korea, Republic of)

    2002-03-15

    Retaining reliabilities of nondestructive testing is essential for the life-time maintenance of Nuclear Power Plant. The nondestructive testing methods which are frequently used in the Nuclear Power Plant are eddy current testing for the inspection of steam generator tubes and ultrasonic testing for the inspection of weldments. In order to improve reliabilities of ultrasonic testing and eddy current testing, the subjects carried out in this study are as follows : development of BEM analysis technique for ECT of SG tube, development of neural network technique for the intelligent analysis of ECT flaw signals of SG tubes, development of RFECT technology for the inspection of SG tube, FEM analysis of ultrasonic scattering field, evaluation of statistical reliability of PD-RR test of ultrasonic testing and development of multi-Gaussian beam modeling technique to predict accurate signal of signal beam ultrasonic testing with the efficiency in calculation time.

  15. ANALYSIS OF AVAILABILITY AND RELIABILITY IN RHIC OPERATIONS

    International Nuclear Information System (INIS)

    PILAT, F.; INGRASSIA, P.; MICHNOFF, R.

    2006-01-01

    RHIC has been successfully operated for 5 years as a collider for different species, ranging from heavy ions including gold and copper, to polarized protons. We present a critical analysis of reliability data for RHIC that not only identifies the principal factors limiting availability but also evaluates critical choices at design times and assess their impact on present machine performance. RHIC availability data are typical when compared to similar high-energy colliders. The critical analysis of operations data is the basis for studies and plans to improve RHIC machine availability beyond the 50-60% typical of high-energy colliders

  16. 76 FR 23222 - Electric Reliability Organization Interpretation of Transmission Operations Reliability

    Science.gov (United States)

    2011-04-26

    ....3d 1342 (DC Cir. 2009). \\5\\ Mandatory Reliability Standards for the Bulk-Power System, Order No. 693... Reliability Standards for the Bulk-Power System. Action: FERC-725A. OMB Control No.: 1902-0244. Respondents...] Electric Reliability Organization Interpretation of Transmission Operations Reliability AGENCY: Federal...

  17. Developing a system engineering program to improve performance and reliability

    International Nuclear Information System (INIS)

    Keuter, D.

    1985-01-01

    After several maintenance, operational, and equipment problems last year, Trojan set out on a mission to improve plant performance and reliability by strengthening its on-site engineering organization. This paper presents Trojan's plans in developing an on-site system engineering organization

  18. Operational experience, availability and reliability of nuclear power plants

    International Nuclear Information System (INIS)

    Kueffer, K.

    1980-01-01

    This lecture - presents a survey on nuclear power production and plant performance in the Western World covering all reactor types and light-water reactors in particular and discusses key parameters such as load factors and non-availability analysis. - outlines the main reasons for the reliable performance of Swiss nuclear power plants - quality equipment - operator qualification and training - engineering know how on site - maintenance philosophy and outage planning - information system and feedback of experience - explains the management functions as applied at the Beznau Nuclear Power Station to ensure high power productivity and reliability - improvement - a feedback control system - analysis of production losses - optimization in shut-down planning - minimizing disturbances during plant operation - optimizing personnel qualification and efficiency. (orig.)

  19. El análisis de criticidad, una metodología para mejorar la confiabilidad operacional // Criticality analysis , a methodology to improve the operational reliability.

    Directory of Open Access Journals (Sweden)

    R. Huerta Mendoza

    2000-10-01

    establecer prioridades, yfocalizar el esfuerzo que garantice el éxito maximizando la rentabilidad.Palabras claves: confiabilidad, criticidad, seguridad, ambiente, riesgo, disponibilidad, mejoramiento.___________________________________________________________________Abstract:The criticality analysis is a methodology that allows to establish the hierarchy or priorities of processes, systems andequipments, creating a structure that facilitates the taking of effective and correct decisions, addressing the effort and theresources in areas where it is more important or necessary to improve the operational dependability, based on the currentreality.The improvement of the operational dependability of any installation or their systems and components is associated withfour fundamental aspects: human dependability, dependability of the process, dependability of the design and thedependability of the maintenance. Regrettably, difficultly is in our hands limitless resources, so much economic as human,to be able to improve at the same time, these four aspects in all the areas of a company.The approaches to carry out a criticality analysis are associated with: security, surroundings, production, operation costsand maintenance, failure rate and repair time mainly. These approaches are related with a mathematical equation thatgenerates punctuation for each evaluated element.The generated list, result of a team work, allows to even and to homologate approaches to establish priorities, and focalisethe effort that guarantees the success maximizing the profitability..Key words:. PDVSA, dependability, criticality, security, surroundings, risk, readiness, improvement,changes.

  20. Operational reliability management; Gestao da confiabilidade operacional

    Energy Technology Data Exchange (ETDEWEB)

    Bressan, Edemir [Refinaria Alberto Pasqualini (REFAP), Canoas, RS (Brazil). Setor de Tecnologia de Equipamentos

    2000-07-01

    It is described the PETROBRAS Alberto Pasqualini Refinery process plant reliability management, strategies, maintenance organizational structure, management processes, predictive and preventive maintenance, condition monitoring techniques, reliability metrics, pointing out a need for close work relationship between production, maintenance and project engineering functions with highly qualified and committed proper teams, in order to reach one of the highest mechanical availability among Latin America refineries. (author)

  1. Prediction of safety critical software operational reliability from test reliability using testing environment factors

    International Nuclear Information System (INIS)

    Jung, Hoan Sung; Seong, Poong Hyun

    1999-01-01

    It has been a critical issue to predict the safety critical software reliability in nuclear engineering area. For many years, many researches have focused on the quantification of software reliability and there have been many models developed to quantify software reliability. Most software reliability models estimate the reliability with the failure data collected during the test assuming that the test environments well represent the operation profile. User's interest is however on the operational reliability rather than on the test reliability. The experiences show that the operational reliability is higher than the test reliability. With the assumption that the difference in reliability results from the change of environment, from testing to operation, testing environment factors comprising the aging factor and the coverage factor are developed in this paper and used to predict the ultimate operational reliability with the failure data in testing phase. It is by incorporating test environments applied beyond the operational profile into testing environment factors. The application results show that the proposed method can estimate the operational reliability accurately. (Author). 14 refs., 1 tab., 1 fig

  2. Enhance pump reliability through improved inservice testing

    International Nuclear Information System (INIS)

    Healy, J.J.

    1990-01-01

    EPRI has undertaken a study to assess the effectiveness of existing testing programs to accurately monitor and predict performance changes before either pump performance degrades or an actual failure occurs. Anticipated changes in inservice testing techniques are directed towards enhancing the validity of test data, ensuring its repeatability, and avoiding deterioration of the pump assembly. There is a new-found interest in test programs of all types that has occurred, in part, because of an increase in reported pump degradation and pump failure. Inservice testing of pumps, which has long been a basis for assuring operability, has apparently produced an opposite effect; namely, the appearance of a reduction in reliability

  3. Analytical modeling of nuclear power station operator reliability

    International Nuclear Information System (INIS)

    Sabri, Z.A.; Husseiny, A.A.

    1979-01-01

    The operator-plant interface is a critical component of power stations which requires the formulation of mathematical models to be applied in plant reliability analysis. The human model introduced here is based on cybernetic interactions and allows for use of available data from psychological experiments, hot and cold training and normal operation. The operator model is identified and integrated in the control and protection systems. The availability and reliability are given for different segments of the operator task and for specific periods of the operator life: namely, training, operation and vigilance or near retirement periods. The results can be easily and directly incorporated in system reliability analysis. (author)

  4. Prediction of software operational reliability using testing environment factor

    International Nuclear Information System (INIS)

    Jung, Hoan Sung

    1995-02-01

    Software reliability is especially important to customers these days. The need to quantify software reliability of safety-critical systems has been received very special attention and the reliability is rated as one of software's most important attributes. Since the software is an intellectual product of human activity and since it is logically complex, the failures are inevitable. No standard models have been established to prove the correctness and to estimate the reliability of software systems by analysis and/or testing. For many years, many researches have focused on the quantification of software reliability and there are many models developed to quantify software reliability. Most software reliability models estimate the reliability with the failure data collected during the test assuming that the test environments well represent the operation profile. User's interest is on the operational reliability rather than on the test reliability, however. The experiences show that the operational reliability is higher than the test reliability. With the assumption that the difference in reliability results from the change of environment, testing environment factor comprising the aging factor and the coverage factor are defined in this work to predict the ultimate operational reliability with the failure data. It is by incorporating test environments applied beyond the operational profile into testing environment factor Test reliability can also be estimated with this approach without any model change. The application results are close to the actual data. The approach used in this thesis is expected to be applicable to ultra high reliable software systems that are used in nuclear power plants, airplanes, and other safety-critical applications

  5. 76 FR 16240 - Mandatory Reliability Standards for Interconnection Reliability Operating Limits

    Science.gov (United States)

    2011-03-23

    ... identified by the Commission. \\5\\ Mandatory Reliability Standards for the Bulk-Power System, Order No. 693... reliability of the interconnection by ensuring that the bulk electric system is assessed during the operations... responsibility for SOLs. Further, Bulk-Power System reliability practices assign responsibilities for analyzing...

  6. EDF/EPRI collaborative program on operator reliability experiments

    International Nuclear Information System (INIS)

    Villemeur, A.; Meslin, T.; Mosneron, F.; Worledge, D.H.; Joksimovich, V.; Spurgin, A.J.

    1988-01-01

    Electricite de France (EDF) and Electric Power Research Institute (EPRI) have been involved in human reliability studies over the last few years, in the context of improvements in human reliability assessment (HRA) methodologies, and have been following a systematic process since 1982 which consists of addressing the following five ingredients: - First, classify human interactions into a limited number of classes. - Second, introduce an acceptable framework to organize the application of HRA to PRA studies. - Third, select approach(es) to quantification. - Fourth, test promising models. - Fifth, establish an appropriate data base for tested model(s) with regard to specific applications. EPRI has just recently completed Phase I of the fourth topic. This primarily focused on testing the fundamental hypotheses behing the human cognitive reliability (HCR) correlation, using power plant simulators. EDF has been carrying out simulator studies since 1980, both for man-machine interface validation and HRA data collection. This background of experience provided a stepping stone for the EPRI project. On the other hand, before 1986, EDF had mainly been concentrating on getting qualitative insights from the tests and lacked experience in quantitative analysis and modeling, while EPRI had made advances in this latter area. Before the EPRI Operator Reliability Experiments (ORE) project was initiated, it was abundantly clear to EPRI and EDF that cooperation between the two could be useful and that both parties could gain from the cooperation

  7. Designing incentive market mechanisms for improving restructured power system reliabilities

    DEFF Research Database (Denmark)

    Ding, Yi; Østergaard, Jacob; Wu, Qiuwei

    2011-01-01

    state. The reliability management of producers usually cannot be directly controlled by the system operators in a restructured power system. Producers may have no motivation to improve their reliabilities, which can result in serious system unreliability issues in the new environment. Incentive market...... mechanisms for improving the restructured power system reliabilities have been designed in this paper. In the proposed incentive mechanisms, penalty will be implemented on a producer if the failures of its generator(s) result in the variation of electricity prices. Incentive market mechanisms can motivate......In a restructured power system, the monopoly generation utility is replaced by different electricity producers. There exists extreme price volatility caused by random failures by generation or/and transmission systems. In these cases, producers' profits can be much higher than those in the normal...

  8. Cost benefit justification of nuclear plant reliability improvement

    International Nuclear Information System (INIS)

    El-Sayed, M.A.H.; Abdelmonem, N.M.

    1985-01-01

    The design of the secondary steam loop of the nuclear power plant has a significant effect on the reliability of the plant. Moreover, the necessity to cool a reactor safely has increased the reliability demanded from the system. The rapidly rising construction costs and fuel prices in recent years have stimulated a great deal in optimizing the productivity of a nuclear power plant through reliability improvement of the secondary steamloop and the reactor cooling system. A method for evaluating the reliability of steam loop and cooling system of a nuclear power plant is presented. The method utilizes the cut-set technique. The developed method can be easily used to show to what extent the overall reliability of the nuclear plant is affected by the possible failures in the steam and cooling subsystem. A model for calculating the increase in the nuclear plant productivity resulting from a proposed improvement in the two subsystems reliability is discussed. The model takes into account the capital cost of spare parts for several components, replacement energy, operating and maintenance costs

  9. Product quality, service reliability and management of operations at ...

    African Journals Online (AJOL)

    High product quality, service reliability, and management of operations are key factors in business growth and sustainability. Analyzing “The Starbucks Experience” is a pedagogical approach to reinforcing the concepts of control and management of quality, service reliability, and efficient operations in action. The objective ...

  10. The Effect of Operations Control on Reliability

    NARCIS (Netherlands)

    Van Oort, N.; Van Nes, R.

    2010-01-01

    Zoetermeer in The Netherlands. During peak hours the frequency on some trajectories is about 24 vehicles an hour. Dealing with these high frequencies and offering travelers a high quality product, according to waiting times as well as the probability of getting a seat, the operator designed a three

  11. Research on Control Method Based on Real-Time Operational Reliability Evaluation for Space Manipulator

    Directory of Open Access Journals (Sweden)

    Yifan Wang

    2014-05-01

    Full Text Available A control method based on real-time operational reliability evaluation for space manipulator is presented for improving the success rate of a manipulator during the execution of a task. In this paper, a method for quantitative analysis of operational reliability is given when manipulator is executing a specified task; then a control model which could control the quantitative operational reliability is built. First, the control process is described by using a state space equation. Second, process parameters are estimated in real time using Bayesian method. Third, the expression of the system's real-time operational reliability is deduced based on the state space equation and process parameters which are estimated using Bayesian method. Finally, a control variable regulation strategy which considers the cost of control is given based on the Theory of Statistical Process Control. It is shown via simulations that this method effectively improves the operational reliability of space manipulator control system.

  12. Ergonomics design and operator training as contributors to human reliability

    International Nuclear Information System (INIS)

    Jackson, A.R.G.; Madden, V.J.; Umbers, I.G.; Williams, J.C.

    1987-01-01

    The safe operation of nuclear reactors depends not only on good physical safety engineering but on the human operators as well. The Central Electricity Generating Board's approach to human reliability includes the following aspects: ergonomics design (task analysis and the development of man-machine interfaces), analysis of human reliability, operational feedback, staff training and assessment, maintenance management, research programmes and management. This paper describes how these combine to achieve the highest practicable level of human reliability, not only for the Sizewell-B pressurized water reactor, but also for the Board's gas-cooled reactors. Examples are used to illustrate the topics considered. (UK)

  13. System 80+ Design and Licensing : Improving Plant Reliability

    International Nuclear Information System (INIS)

    Newman, Robert E.

    1989-01-01

    The U. S. nuclear industry is striving to improve plant reliability and availability through improved plant design, component designs and plant maintenance. In an effort to improve safety and to demonstrate that commercial nuclear power is economically competitive with other energy sources, the utilities, nuclear vendors, architect engineers and constructors, and component suppliers are all participating in an industry-wide effort to develop improved Light Water Reactor (LWR) designs that are based upon the many years of successful LWR operation. In an age when the world faces the environmental pressures of the greenhouse effect and acid rain, electricity generated from nuclear energy must play an increasing role in the energy picture of Korea, the United States and the rest of the world. This paper discusses the plant availability requirement that has been established by the industry-wide effort mentioned above. After briefly describing Combustion Engineering's program for development of the System 80 Plus standard design and the participation of the Korea Advanced Energy Research Institute (KAERI) in the program, the paper then describes the design features that are being incorporated into System 80+. The industry ALRR Program has established a very ambitious criterion of 87% for the plant availability of future nuclear units. To satisfy such a requirement, the next generation of nuclear plants will include a great many design improvements that reflect the hundreds of years of operating experience that we have accrued. C-ESA's System 80+ will include a number of design changes that improve operating margins and make the plant easier to operate and maintain. Not surprisingly, there is a great deal of overlap between improved safety and improved reliability. In the end, our design will satisfy the future needs of the utilities, the regulators, and the public. C-E is very pleased that KAERI is working with US to achieve these important goals

  14. Theory model and experiment research about the cognition reliability of nuclear power plant operators

    International Nuclear Information System (INIS)

    Fang Xiang; Zhao Bingquan

    2000-01-01

    In order to improve the reliability of NPP operation, the simulation research on the reliability of nuclear power plant operators is needed. Making use of simulator of nuclear power plant as research platform, and taking the present international reliability research model-human cognition reliability for reference, the part of the model is modified according to the actual status of Chinese nuclear power plant operators and the research model of Chinese nuclear power plant operators obtained based on two-parameter Weibull distribution. Experiments about the reliability of nuclear power plant operators are carried out using the two-parameter Weibull distribution research model. Compared with those in the world, the same results are achieved. The research would be beneficial to the operation safety of nuclear power plant

  15. Developing methods for establishing improved plant reliability

    International Nuclear Information System (INIS)

    Zebroski, E.L.; Lapides, M.E.; Johnson, L.

    1976-01-01

    The current average capacity factor for nuclear electric generating facilities is approximately 60 percent, virtually the same as that for large, modern fossil-fired units. There is a clear cost advantage for nuclear electrical generation in comparison to coal-fired units at a common performance level. Because of the accelerated increase in capital and fuel costs of coal-fired units, the nuclear units will usually exhibit a cost advantage even when operating at lower capacity factor values. The incentives for improvement follow from the utility objectives to provide electricity at the most economical rates possible and are reflected in reduced system fuel costs and capital requirements. These objectives require maximizing the productivity of existing or planned investments in nuclear generation. The requirements are to: (1) achieve and sustain the highest capacity factor consistent with each utility's electric transmission system configuration and demand; (2) accelerate the rate of attainment of operational ''maturity'' of new generation; and (3) avoid low-probability but large-consequence forced-outage events. Nuclear unit productivity improvement involves utilities, regulatory agencies and industrial and government research and development organizations; the efforts appropriate to each organization were identified in a previous study. Since no foreseeable set of warranties begins to cover the consequential costs of low performance, the greatest incentive for improvement rests with each individual utility. The paper addresses the methodology and information sources for productivity actions by utilities during unit procurement and design phases

  16. 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.)

  17. Improvement of plant reliability in PT. Badak LNG plant

    International Nuclear Information System (INIS)

    Achmad, S.; Somantri, A.

    1997-01-01

    PT. Badak's LNG sales commitment has been steadily increasing, therefore, there has been more emphasis to improve and maintain the LNG plant reliability. From plant operation historical records, Badak LNG plant experienced a high number of LNG process train trips and down time for 1977 through 1988. The highest annual number of LNG plant trips (50 times) occurred in 1983 and the longest LNG process train down time (1259 train-hours) occurred in 1988. Since 1989, PT. Badak has been able to reduce the number of LNG process train trips and down time significantly. In 1994 the number of LNG process train trips and was 18 times and the longest LNG process train down time was 377 train-hours. This plant reliability improvement was achieved by implementing plant reliability improvement programs beginning with the design of the new facilities and continuing with the maintenance and modification of the existing facilities. To improve reliability of the existing facilities, PT. Badak has been implementing comprehensive maintenance programs, to reduce the frequency and down time of the plant, such as Preventive and Predictive Maintenance as well as procurement material improvement since PT. Badak location is in a remote area. By implementing the comprehensive reliability maintenance, PT. Badak has been able to reduce the LNG process train trips to 18 and down time to 337 train hours in 1994 with the subsequent maintenance cost reduction. The average PT. Badak plant availability from 1985 to 1995 is 94.59%. New facilities were designed according to the established PT. Badak design philosophy, master plan and specification. Design of new facilities was modified to avoid certain problems from past experience. (au)

  18. Operator adaptation to changes in system reliability under adaptable automation.

    Science.gov (United States)

    Chavaillaz, Alain; Sauer, Juergen

    2017-09-01

    This experiment examined how operators coped with a change in system reliability between training and testing. Forty participants were trained for 3 h on a complex process control simulation modelling six levels of automation (LOA). In training, participants either experienced a high- (100%) or low-reliability system (50%). The impact of training experience on operator behaviour was examined during a 2.5 h testing session, in which participants either experienced a high- (100%) or low-reliability system (60%). The results showed that most operators did not often switch between LOA. Most chose an LOA that relieved them of most tasks but maintained their decision authority. Training experience did not have a strong impact on the outcome measures (e.g. performance, complacency). Low system reliability led to decreased performance and self-confidence. Furthermore, complacency was observed under high system reliability. Overall, the findings suggest benefits of adaptable automation because it accommodates different operator preferences for LOA. Practitioner Summary: The present research shows that operators can adapt to changes in system reliability between training and testing sessions. Furthermore, it provides evidence that each operator has his/her preferred automation level. Since this preference varies strongly between operators, adaptable automation seems to be suitable to accommodate these large differences.

  19. Can We Make Operating Systems Reliable and Secure?

    NARCIS (Netherlands)

    Tanenbaum, A.S.; Herder, J.N.; Bos, H.J.

    2006-01-01

    Microkernels--long discarded as unacceptable because of their lower performance compared with monolithic kernels--might be making a comeback in operating systems due to their potentially higher reliability, which many researchers now regard as more important than performance.

  20. Reliable file sharing in distributed operating system using web RTC

    Science.gov (United States)

    Dukiya, Rajesh

    2017-12-01

    Since, the evolution of distributed operating system, distributed file system is come out to be important part in operating system. P2P is a reliable way in Distributed Operating System for file sharing. It was introduced in 1999, later it became a high research interest topic. Peer to Peer network is a type of network, where peers share network workload and other load related tasks. A P2P network can be a period of time connection, where a bunch of computers connected by a USB (Universal Serial Bus) port to transfer or enable disk sharing i.e. file sharing. Currently P2P requires special network that should be designed in P2P way. Nowadays, there is a big influence of browsers in our life. In this project we are going to study of file sharing mechanism in distributed operating system in web browsers, where we will try to find performance bottlenecks which our research will going to be an improvement in file sharing by performance and scalability in distributed file systems. Additionally, we will discuss the scope of Web Torrent file sharing and free-riding in peer to peer networks.

  1. Fuel improvement and WWER-1000 FA main operational results

    International Nuclear Information System (INIS)

    Rozhkov, V.; Enin, A.; Bezborodov, Y.; Petrov, V.

    2003-01-01

    The JSC NCCP experience of WWER-1000 Fuel Assemblies (FAs) fabrication and operation confirms the adequate feasibility and efficiency of fuel operation in 3-4-x fuel cycles, high operating reliability and competitive capacity as compared with foreign analogues. The work on fuel improvement is aimed at an improvement of the operating reliability and an enhancement of the fuel use efficiency in WWER-1000 advanced FAs

  2. Nuclear electric propulsion operational reliability and crew safety study

    International Nuclear Information System (INIS)

    Karns, J.J.; Fragola, J.R.; Kahan, L.; Pelaccio, D.

    1993-01-01

    The central purpose of this analysis is to assess the ''achievability'' of a nuclear electric propulsion (NEP) system in a given mission. ''Achievability'' is a concept introduced to indicate the extent to which a system that meets or achieves its design goals might be implemented using the existing technology base. In the context of this analysis, the objective is to assess the achievability of an NEP system for a manned Mars mission as it pertains to operational reliability and crew safety goals. By varying design parameters, then examining the resulting system achievability, the design and mission risk drivers can be identified. Additionally, conceptual changes in design approach or mission strategy which are likely to improve overall achievability of the NEP system can be examined

  3. Use of Human Reliability Insights to Improve Decision-Making

    International Nuclear Information System (INIS)

    Julius, J. A.; Moieni, P.; Grobbelaar, J.; Kohlhepp, K.

    2016-01-01

    This paper describes the use of insights obtained during the development and application of human reliability analysis (HRA) as part of a probabilistic risk assessment (PRA) to support decision-making, including improvements to operations, training, and safety culture. Insights have been gained from the development and application of HRA as part of a PRA for nuclear power plants in the USA, Europe and Asia over the last two decades. These models consist of Level 1 and Level 2 PRA models of internal and external events, during full power and shutdown modes of plant operation. These insights include the use of human factors information to improve the qualitative portion of the HRA. The subsequent quantification in the HRA effectively prioritises the contributors to the unreliability of operator actions, and the process facilitates the identification of the factors that are important to the success of the operator actions. Additionally, the tools and techniques also allow for the evaluation of key assumptions and sources of uncertainty. The end results have been used to effectively support decision-making for day-to-day plant operations as well as licensing issues. HRA results have been used to provide feedback and improvements to plant procedures, operator training and other areas contributing the plant safety culture. Examples of the types of insights are presented in this paper. (author)

  4. Operational reliability testing of FBR fuel in EBR-II

    International Nuclear Information System (INIS)

    Asaga, Takeo; Ukai, Shigeharu; Nomura, Shigeo; Shikakura, Sakae

    1991-01-01

    The operational reliability testing of FBR fuel has been conducting in EBR-II as a DOE/PNC collaboration program. This paper reviews the achieved summary of Phase-I test as well as outline of progressing Phase-II test. In Phase-I test, the reliability of FBR fuel pins including 'MONJU' fuel was demonstrated at the event of operational transient. Continued operation of the failed pins was also shown to be feasible without affecting the plant operation. The objectives of the Phase-II test is to extend the data base relating with the operational reliability for long life fuel, and to supply the highly quantitative evaluation. The valuable insight obtained in Phase-II test are considerably expected to be useful toward the achievement of commercial FBR. (author)

  5. The evaluation of operator reliability factors on power reactor

    International Nuclear Information System (INIS)

    Karlina, Itjeu; Supriatna, Piping; W, Suharyo; Santosa, Kussigit; Darlis; S, Bambang; Y, Sasongko

    1999-01-01

    The sophisticated technology system was not assured the reliability system itself because it has contained a part of human dependence affected successfully of reactor operation either how work smoothly and safe or failure ac cured and then accident appears promptly. The evaluation of operator reliability factor on ABWR power reactor has been carried out which consist of criterion skill and workload according to NUREG/CR-2254, NUREG/CR-4016 and NUREG-0835 the reactor operation reliability emphasize to the operator are synergic between skill and workload themselves. The employee's skill will affect to the type and level of their tasks. The operator's skill depend on education and experiences, position or responsibility of tasks, physical conditions (age uninvalid of physic/mental

  6. SOFC Systems with Improved Reliability and Endurance

    Energy Technology Data Exchange (ETDEWEB)

    Ghezel-Ayagh, Hossein [Fuelcell Energy, Incorporated, Danbury, CT (United States)

    2015-12-31

    The overall goal of this U.S. Department of Energy (DOE) sponsored project was the development of Solid Oxide Fuel Cell (SOFC) technology suitable for ultra-efficient central power generation systems utilizing coal and natural gas fuels and featuring greater than 90% carbon dioxide capture. The specific technical objective of this project was to demonstrate, via analyses and testing, progress towards adequate stack life (≥ 4 years) and stack performance stability (degradation rate ≤ 0.2% per 1000 hours) in a low-cost SOFC stack design. This final technical report summarizes the progress made during the project period of 27 months. Significant progress was made in the areas of cell and stack technology development, stack module development, sub-scale module tests, and Proof-of-Concept Module unit design, fabrication and testing. The work focused on cell and stack materials and designs, balance-of-plant improvements, and performance evaluation covering operating conditions and fuel compositions anticipated for commercially-deployed systems. In support of performance evaluation under commercial conditions, this work included the design, fabrication, siting, commissioning, and operation of a ≥ 50 kWe proof-of-concept module (PCM) power plant, based upon SOFC cell and stack technology developed to date by FuelCell Energy, Inc. (FCE) under the Office of Fossil Energy’s Solid Oxide Fuel Cells program. The PCM system was operated for at least 1000 hours on natural gas fuel at FCE’s facility. The factory cost of the SOFC stack was estimated to be at or below the DOE’s high-volume production cost target (2011 $).

  7. Optimum reliable operation of water distribution networks by ...

    African Journals Online (AJOL)

    In recent decades much attention has been paid to optimal operation of water distribution networks (WDNs). In this regard, the system operation costs, including energy and disinfection chemicals, as well as system reliability should be simultaneously considered in system performance optimisation, to provide the minimum ...

  8. Optimizing the design and operation of reactor emergency systems using reliability analysis techniques

    International Nuclear Information System (INIS)

    Snaith, E.R.

    1975-01-01

    Following a reactor trip various reactor emergency systems, e.g. essential power supplies, emergency core cooling and boiler feed water arrangements are required to operate with a high degree of reliability. These systems must therefore be critically assessed to confirm their capability of operation and determine their reliability of performance. The use of probability analysis techniques enables the potential operating reliability of the systems to be calculated and this can then be compared with the overall reliability requirements. However, a system reliability analysis does much more than calculate an overall reliability value for the system. It establishes the reliability of all parts of the system and thus identifies the most sensitive areas of unreliability. This indicates the areas where any required improvements should be made and enables the overall systems' designs and modes of operation to be optimized, to meet the system and hence the overall reactor safety criteria. This paper gives specific examples of sensitive areas of unreliability that were identified as a result of a reliability analysis that was carried out on a reactor emergency core cooling system. Details are given of modifications to design and operation that were implemented with a resulting improvement in reliability of various reactor sub-systems. The report concludes that an initial calculation of system reliability should represent only the beginning of continuing process of system assessment. Data on equipment and system performance, particularly in those areas shown to be sensitive in their effect on the overall nuclear power plant reliability, should be collected and processed to give reliability data. These data should then be applied in further probabilistic analyses and the results correlated with the original analysis. This will demonstrate whether the required and the originally predicted system reliability is likely to be achieved, in the light of the actual history to date of

  9. Technical information report: Plasma melter operation, reliability, and maintenance analysis

    International Nuclear Information System (INIS)

    Hendrickson, D.W.

    1995-01-01

    This document provides a technical report of operability, reliability, and maintenance of a plasma melter for low-level waste vitrification, in support of the Hanford Tank Waste Remediation System (TWRS) Low-Level Waste (LLW) Vitrification Program. A process description is provided that minimizes maintenance and downtime and includes material and energy balances, equipment sizes and arrangement, startup/operation/maintence/shutdown cycle descriptions, and basis for scale-up to a 200 metric ton/day production facility. Operational requirements are provided including utilities, feeds, labor, and maintenance. Equipment reliability estimates and maintenance requirements are provided which includes a list of failure modes, responses, and consequences

  10. Database reliability engineering designing and operating resilient database systems

    CERN Document Server

    Campbell, Laine

    2018-01-01

    The infrastructure-as-code revolution in IT is also affecting database administration. With this practical book, developers, system administrators, and junior to mid-level DBAs will learn how the modern practice of site reliability engineering applies to the craft of database architecture and operations. Authors Laine Campbell and Charity Majors provide a framework for professionals looking to join the ranks of today’s database reliability engineers (DBRE). You’ll begin by exploring core operational concepts that DBREs need to master. Then you’ll examine a wide range of database persistence options, including how to implement key technologies to provide resilient, scalable, and performant data storage and retrieval. With a firm foundation in database reliability engineering, you’ll be ready to dive into the architecture and operations of any modern database. This book covers: Service-level requirements and risk management Building and evolving an architecture for operational visibility ...

  11. Improvement of Equipment reliability for Auxiliary Feed Water System

    Energy Technology Data Exchange (ETDEWEB)

    Deok, Lee Sang; Kwan, Lee Yong [KEPCO International Nuclear Graduate School, Ulsan (Korea, Republic of)

    2013-10-15

    According to AP913 ER) of INPO, Number of the event related to equipment is higher than others like external or human performance. In the top 25 systems, Auxiliary feed water system is the seventh highest among systems. AWFS consists of many component and complex system and Main Function of AFWS is to supply feedwater to the steam generators for the removal of heat from the RCS(Reactor Coolant System) in event the main feedwater system is unavailable following a transient or accident. Reliability of component means how well operate on demands and monitoring is necessary to keep track of condition of component. If component performance is lower than the required value, corrective action for failure mode should be done. The objective of this study is focused to improve of AF pump by adding the tasks of SHR(System Health Report) into the task of system engineer walkdown of PMT(Preventive Maintenance Template). Increasing the reliability of AF pump will contribute to improvement of reliability of AFWS. Based on operating history, there was high vibration of AF pump during performance test. In that case, there were a lot of maintenance works for normal operation of AF pump. Vibration problem related pump can't be detected by tasks of SE walkdown because it's not running during normal operation except for surveillance test. CHR(Component Health Report) of AF pump in AFWS can be made from necessary part which means monitoring and functional failure because problem of Stand-by pump can be covered by conducting monitoring and analysis of functional failure. To improve reliability of AF pump, walkdown of PMT and SHR should be conducted both in accordance with surveillance test frequency. Health of AF pump based on operation history can be verified first and then can find out which parts of pump are weak. Finally, weak part can be managed intensively and failure can be reduced according to SE walkdown. But this work can be risky and burdensome because all parts of

  12. The commissioning of CMS sites: Improving the site reliability

    International Nuclear Information System (INIS)

    Belforte, S; Fisk, I; Flix, J; Hernandez, J M; Klem, J; Letts, J; Magini, N; Saiz, P; Sciaba, A

    2010-01-01

    The computing system of the CMS experiment works using distributed resources from more than 60 computing centres worldwide. These centres, located in Europe, America and Asia are interconnected by the Worldwide LHC Computing Grid. The operation of the system requires a stable and reliable behaviour of the underlying infrastructure. CMS has established a procedure to extensively test all relevant aspects of a Grid site, such as the ability to efficiently use their network to transfer data, the functionality of all the site services relevant for CMS and the capability to sustain the various CMS computing workflows at the required scale. This contribution describes in detail the procedure to rate CMS sites depending on their performance, including the complete automation of the program, the description of monitoring tools, and its impact in improving the overall reliability of the Grid from the point of view of the CMS computing system.

  13. Photovoltaic module reliability improvement through application testing and failure analysis

    Science.gov (United States)

    Dumas, L. N.; Shumka, A.

    1982-01-01

    During the first four years of the U.S. Department of Energy (DOE) National Photovoltatic Program, the Jet Propulsion Laboratory Low-Cost Solar Array (LSA) Project purchased about 400 kW of photovoltaic modules for test and experiments. In order to identify, report, and analyze test and operational problems with the Block Procurement modules, a problem/failure reporting and analysis system was implemented by the LSA Project with the main purpose of providing manufacturers with feedback from test and field experience needed for the improvement of product performance and reliability. A description of the more significant types of failures is presented, taking into account interconnects, cracked cells, dielectric breakdown, delamination, and corrosion. Current design practices and reliability evaluations are also discussed. The conducted evaluation indicates that current module designs incorporate damage-resistant and fault-tolerant features which address field failure mechanisms observed to date.

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

    Directory of Open Access Journals (Sweden)

    Saeed Shahrezaei

    2013-04-01

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

  15. Improvement of human reliability analysis method for PRA

    International Nuclear Information System (INIS)

    Tanji, Junichi; Fujimoto, Haruo

    2013-09-01

    It is required to refine human reliability analysis (HRA) method by, for example, incorporating consideration for the cognitive process of operator into the evaluation of diagnosis errors and decision-making errors, as a part of the development and improvement of methods used in probabilistic risk assessments (PRAs). JNES has been developed a HRA method based on ATHENA which is suitable to handle the structured relationship among diagnosis errors, decision-making errors and operator cognition process. This report summarizes outcomes obtained from the improvement of HRA method, in which enhancement to evaluate how the plant degraded condition affects operator cognitive process and to evaluate human error probabilities (HEPs) which correspond to the contents of operator tasks is made. In addition, this report describes the results of case studies on the representative accident sequences to investigate the applicability of HRA method developed. HEPs of the same accident sequences are also estimated using THERP method, which is most popularly used HRA method, and comparisons of the results obtained using these two methods are made to depict the differences of these methods and issues to be solved. Important conclusions obtained are as follows: (1) Improvement of HRA method using operator cognitive action model. Clarification of factors to be considered in the evaluation of human errors, incorporation of degraded plant safety condition into HRA and investigation of HEPs which are affected by the contents of operator tasks were made to improve the HRA method which can integrate operator cognitive action model into ATHENA method. In addition, the detail of procedures of the improved method was delineated in the form of flowchart. (2) Case studies and comparison with the results evaluated by THERP method. Four operator actions modeled in the PRAs of representative BWR5 and 4-loop PWR plants were selected and evaluated as case studies. These cases were also evaluated using

  16. 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.

  17. Improved reliability of residential heat pumps; Foerbaettrad driftsaekerhet hos villavaermepumpar

    Energy Technology Data Exchange (ETDEWEB)

    Haglund Stignor, Caroline; Larsson, Kristin; Jensen, Sara; Larsson, Johan; Berg, Johan; Lidbom, Peter; Rolfsman, Lennart

    2012-07-01

    Today, heat pump heating systems are common in Swedish single-family houses. Many owners are pleased with their installation, but statistics show that a certain number of heat pumps break every year, resulting in high costs for both insurance companies and owners. On behalf of Laensfoersaekringars Forskningsfond, SP Energy Technology has studied the cause of the most common failures for residential heat pumps. The objective of the study was to suggest what measures to be taken to reduce the number of failures, i.e. improving the reliability of heat pumps. The methods used were analysis of public failure statistics and sales statistics and interviews with heat pump manufacturers, installers, service representatives and assessors at Laensfoersaekringar. In addition, heat pump manuals have been examined and literature searches for various methods for durability tests have been performed. Based on the outcome from the interviews the most common failures were categorized by if they; 1. Could have been prevented by better operation and maintenance of the heat pump. 2. Caused by a poorly performed installation. 3. Could have been prevented if certain parameters had been measured, recorded and followed up. 4. Are due to poor quality of components or systems. However, the results show that many of the common failures fall into several different categories and therefore, different types of measures must be taken to improve the operational reliability of residential heat pumps. The interviews tell that failures often are caused by poor installation, neglected maintenance and surveillance, and poor quality of standard components or that components are used outside their declared operating range. The quality of the installations could be improved by increasing installers' knowledge about heat pumps and by requiring that an installation protocol shall be filled-in. It is also important that the owner of the heat pump performs the preventive maintenance recommended by the

  18. Improved reliability of residential heat pumps; Foerbaettrad driftsaekerhet hos villavaermepumpar

    Energy Technology Data Exchange (ETDEWEB)

    Haglund Stignor, Caroline; Larsson, Kristin; Jensen, Sara; Larsson, Johan; Berg, Johan; Lidbom, Peter; Rolfsman, Lennart

    2012-07-01

    Today, heat pump heating systems are common in Swedish single-family houses. Many owners are pleased with their installation, but statistics show that a certain number of heat pumps break every year, resulting in high costs for both insurance companies and owners. On behalf of Laensfoersaekringars Forskningsfond, SP Energy Technology has studied the cause of the most common failures for residential heat pumps. The objective of the study was to suggest what measures to be taken to reduce the number of failures, i.e. improving the reliability of heat pumps. The methods used were analysis of public failure statistics and sales statistics and interviews with heat pump manufacturers, installers, service representatives and assessors at Laensfoersaekringar. In addition, heat pump manuals have been examined and literature searches for various methods for durability tests have been performed. Based on the outcome from the interviews the most common failures were categorized by if they; 1. Could have been prevented by better operation and maintenance of the heat pump. 2. Caused by a poorly performed installation. 3. Could have been prevented if certain parameters had been measured, recorded and followed up. 4. Are due to poor quality of components or systems. However, the results show that many of the common failures fall into several different categories and therefore, different types of measures must be taken to improve the operational reliability of residential heat pumps. The interviews tell that failures often are caused by poor installation, neglected maintenance and surveillance, and poor quality of standard components or that components are used outside their declared operating range. The quality of the installations could be improved by increasing installers' knowledge about heat pumps and by requiring that an installation protocol shall be filled-in. It is also important that the owner of the heat pump performs the preventive maintenance recommended by the

  19. software reliability: failures, consequences and improvement

    African Journals Online (AJOL)

    BARTH EKWUEME

    2009-07-16

    Jul 16, 2009 ... function of time, but it is believed that some modeling technique for software reliability is reaching propensity, by ..... February 25, 1991 during the Gulf war, the chopping ... Let us consider a few key concepts that apply to both.

  20. Developing Predictive Maintenance Expertise to Improve Plant Equipment Reliability

    International Nuclear Information System (INIS)

    Wurzbach, Richard N.

    2002-01-01

    On-line equipment condition monitoring is a critical component of the world-class production and safety histories of many successful nuclear plant operators. From addressing availability and operability concerns of nuclear safety-related equipment to increasing profitability through support system reliability and reduced maintenance costs, Predictive Maintenance programs have increasingly become a vital contribution to the maintenance and operation decisions of nuclear facilities. In recent years, significant advancements have been made in the quality and portability of many of the instruments being used, and software improvements have been made as well. However, the single most influential component of the success of these programs is the impact of a trained and experienced team of personnel putting this technology to work. Changes in the nature of the power generation industry brought on by competition, mergers, and acquisitions, has taken the historically stable personnel environment of power generation and created a very dynamic situation. As a result, many facilities have seen a significant turnover in personnel in key positions, including predictive maintenance personnel. It has become the challenge for many nuclear operators to maintain the consistent contribution of quality data and information from predictive maintenance that has become important in the overall equipment decision process. These challenges can be met through the implementation of quality training to predictive maintenance personnel and regular updating and re-certification of key technology holders. The use of data management tools and services aid in the sharing of information across sites within an operating company, and with experts who can contribute value-added data management and analysis. The overall effectiveness of predictive maintenance programs can be improved through the incorporation of newly developed comprehensive technology training courses. These courses address the use of

  1. Improvement of standards on functional reliability of electric power systems

    International Nuclear Information System (INIS)

    Barinov, V.A.; Volkov, G.A.; Kalita, V.V.; Kogan, F.L.; Makarov, S.F.; Manevich, A.S.; Mogirev, V.V.; Sin'chugov, F.I.; Skopintsev, V.A.; Khvoshchinskaya, Z.G.

    1993-01-01

    Analysis of the most principal aspects of the existing standards and requirements on assuring safety and stability of electric power systems (EPS) and effective (reliable and economical) power supply of consumers is given. The reliability is determined as ability to accomplish the assigned functions. Basic recommendations on improving the standards regulating the safety and reliability of the NPP functioning are formulated

  2. Improved core monitoring for improved plant operations

    International Nuclear Information System (INIS)

    Mueller, N.P.

    1987-01-01

    Westinghouse has recently installed a core on-line surveillance, monitoring and operations systems (COSMOS), which uses only currently available core and plant data to accurately reconstruct the core average axial and radial power distributions. This information is provided to the operator in an immediately usable, human-engineered format and is accumulated for use in application programs that provide improved core performance predictive tools and a data base for improved fuel management. Dynamic on-line real-time axial and radial core monitoring supports a variety of plant operations to provide a favorable cost/benefit ratio for such a system. Benefits include: (1) relaxation or elimination of certain technical specifications to reduce surveillance and reporting requirements and allow higher availability factors, (2) improved information displays, predictive tools, and control strategies to support more efficient core control and reduce effluent production, and (3) expanded burnup data base for improved fuel management. Such systems can be backfit into operating plants without changing the existing instrumentation and control system and can frequently be implemented on existing plant computer capacity

  3. Improvement for BWR operator training

    International Nuclear Information System (INIS)

    Tsuchiya, Toshio; Masuda, Hisao; Isono, Tomoyuki; Noji, Kunio; Togo, Toshiki

    1989-01-01

    BWR Operator Training Center Corporation (BTC) was established in April 1971 for the purpose of training the operators from all BWR utilities in Japan. Since April 1974, more than 2600 operators and 1000 shift teams have been trained with the full-scope simulators in BTC up to the end of March 1988. To get the satisfactory results of the training, BTC has been making every effort to improve the facilities, the training materials, the instruction methods and the curricula. In this paper, such a series of recent improvements in the instruction methods and the curricula are presented that are effective to expand the knowledge and to improve the skills of middle or senior class operators. (author)

  4. Planning of operation & maintenance using risk and reliability based methods

    DEFF Research Database (Denmark)

    Florian, Mihai; Sørensen, John Dalsgaard

    2015-01-01

    Operation and maintenance (OM) of offshore wind turbines contributes with a substantial part of the total levelized cost of energy (LCOE). The objective of this paper is to present an application of risk- and reliability-based methods for planning of OM. The theoretical basis is presented...

  5. Advanced reliability improvement of AC-modules (ARIA)

    International Nuclear Information System (INIS)

    Rooij, P.; Real, M.; Moschella, U.; Sample, T.; Kardolus, M.

    2001-09-01

    The AC-module is a relatively new development in PV-system technology and offers significant advantages over conventional PV-systems with a central inverter : e.g. increased modularity, ease of installation and freedom of system design. The Netherlands and Switzerland have a leading position in the field of AC-modules, both in terms of technology and of commercial and large-scale application. An obstacle towards large-scale market introduction of AC-modules is that the reliability and operational lifetime of AC-modules and the integrated inverters in particular are not yet proven. Despite the advantages, no module-integrated inverter has yet achieved large scale introduction. The AC-modules will lower the barrier towards market penetration. But due to the great interest in the new AC-module technology there is the risk of introducing a not fully proven product. This may damage the image of PV-systems. To speed up the development and to improve the reliability, research institutes and PV-industry will address the aspects of reliability and operational lifetime of AC-modules. From field experiences we learn that in general the inverter is still the weakest point in PV-systems. The lifetime of inverters is an important factor on reliability. Some authors are indicating a lifetime of 1.5 years, whereas the field experiences in Germany and Switzerland have shown that for central inverter systems, an availability of 97% has been achieved in the last years. From this point of view it is highly desirable that the operational lifetime and reliability of PV-inverters and especially AC-modules is demonstrated/improved to make large scale use of PV a success. Module Integrated Inverters will most likely be used in modules in the power range between 100 and 300 Watt DC-power. These are modules with more than 100 cells in series, assuming that the module inverter will benefit from the higher voltage. Hot-spot is the phenomenon that can occur when one or more cells of a string

  6. SLAC modulator operation and reliability in the SLC Era

    International Nuclear Information System (INIS)

    Donaldson, A.R.; Ashton, J.R.

    1992-06-01

    A discussion of the operation and reliability of the 244 modulators in the SLAC linac with an emphasis on the past three years of operation. The linac modulators were designed and built in the 60's, upgraded for the SLAC Linear Collider (SLC) in the mid 80s, and despite their age are still reliable accelerator components. The 60s modulator operated at 65 MW peak and 83 kW average power. The upgrade resulted in 150 MW peak output at an average power of 87 kW, a modest increase since the repetition rate was dropped from 360 to 120 Hz. In the present accelerator configuration, the Linac operates as a source of electrons and positrons to a single pass coillider. The classic collider is a storage ring filled with oppositely charged, counter-rotating particles which are allowed to collide until an accelerator fault occurs and the stored beams are aborted. A reasonable storage ring can store and collide particles for as long as eight hours with a 10 or 20 minute filling time. A single pass collider, + on the other hand, can only produce e - and e + collisions at whatever rate the source operates. To be effective the SLC must operate at 120 Hz with a very high degree of reliability and on a continuous basis. Fortunately, the linac has a modest excess of modulator/klystron systems which allows some measure of redundancy and hence some freedom from the constraint that all 244 modulator/klystrons operate simultaneously. Nonetheless, high importance is placed on modulator MTBF and MTRR or, in the parlance of reliability experts and accelerator physicists, availability. This is especially true of the modulators associated with the fundamental requirements of a collider such as injection, compression and positron production

  7. Reliability evaluation of oil pipelines operating in aggressive environment

    Science.gov (United States)

    Magomedov, R. M.; Paizulaev, M. M.; Gebel, E. S.

    2017-08-01

    In connection with modern increased requirements for ecology and safety, the development of diagnostic services complex is obligatory and necessary enabling to ensure the reliable operation of the gas transportation infrastructure. Estimation of oil pipelines technical condition should be carried out not only to establish the current values of the equipment technological parameters in operation, but also to predict the dynamics of changes in the physical and mechanical characteristics of the material, the appearance of defects, etc. to ensure reliable and safe operation. In the paper, existing Russian and foreign methods for evaluation of the oil pipelines reliability are considered, taking into account one of the main factors leading to the appearance of crevice in the pipeline material, i.e. change the shape of its cross-section, - corrosion. Without compromising the generality of the reasoning, the assumption of uniform corrosion wear for the initial rectangular cross section has been made. As a result a formula for calculation the probability of failure-free operation was formulated. The proposed mathematical model makes it possible to predict emergency situations, as well as to determine optimal operating conditions for oil pipelines.

  8. Improvement of PWR reliability by corrosion prevention

    International Nuclear Information System (INIS)

    Takamatsu, Hiroshi

    1999-01-01

    Since first PWR in Japan started commercial operation in 1970, we have encountered the various modes of corrosion on primary and secondary side components. We have paid much efforts for resolving these corrosion problems, that is, investigating the causes of corrosion and establishing the countermeasures for these corrosion. We summarize these efforts in this article. (author)

  9. Approach to assurance of reliability of linear accelerator operation observations

    International Nuclear Information System (INIS)

    Bakov, S.M.; Borovikov, A.A.; Kavkun, S.L.

    1994-01-01

    The system approach to solving the task of assuring reliability of observations over the linear accelerator operation is proposed. The basic principles of this method consist in application of dependences between the facility parameters, decrease in the number of the system apparatus channels for data acquisition without replacement of failed channel by reserve one. The signal commutation unit, the introduction whereof into the data acquisition system essentially increases the reliability of the measurement system on the account of active reserve, is considered detail. 8 refs. 6 figs

  10. Achieving High Reliability Operations Through Multi-Program Integration

    Energy Technology Data Exchange (ETDEWEB)

    Holly M. Ashley; Ronald K. Farris; Robert E. Richards

    2009-04-01

    Over the last 20 years the Idaho National Laboratory (INL) has adopted a number of operations and safety-related programs which has each periodically taken its turn in the limelight. As new programs have come along there has been natural competition for resources, focus and commitment. In the last few years, the INL has made real progress in integrating all these programs and are starting to realize important synergies. Contributing to this integration are both collaborative individuals and an emerging shared vision and goal of the INL fully maturing in its high reliability operations. This goal is so powerful because the concept of high reliability operations (and the resulting organizations) is a masterful amalgam and orchestrator of the best of all the participating programs (i.e. conduct of operations, behavior based safety, human performance, voluntary protection, quality assurance, and integrated safety management). This paper is a brief recounting of the lessons learned, thus far, at the INL in bringing previously competing programs into harmony under the goal (umbrella) of seeking to perform regularly as a high reliability organization. In addition to a brief diagram-illustrated historical review, the authors will share the INL’s primary successes (things already effectively stopped or started) and the gaps yet to be bridged.

  11. Improving Reliability in a Stochastic Communication Network

    Science.gov (United States)

    1990-12-01

    and GINO. In addition, the following computers were used: a Sun 386i workstation, a Digital Equipment Corporation (DEC) 11/785 miniframe , and a DEC...operating system. The DEC 11/785 miniframe used in the experiment was running Unix Version 4.3 (Berkley System Domain). Maxflo was run on the DEC 11/785...the file was still called Mod- ifyl.for). 4. The Maxflo program was started on the DEC 11/785 miniframe . 5. At this time the Convert.max file, created

  12. SRC: FenixOS - A Research Operating System Focused on High Scalability and Reliability

    DEFF Research Database (Denmark)

    Passas, Stavros; Karlsson, Sven

    2011-01-01

    Computer systems keep increasing in size. Systems scale in the number of processing units, memories and peripheral devices. This creates many and diverse architectural trade-offs that the existing operating systems are not able to address. We are designing and implementing, FenixOS, a new operating...... of the operating system....... system that aims to improve the state of the art in scalability and reliability. We achieve scalability through limiting data sharing when possible, and through extensive use of lock-free data structures. Reliability is addressed with a careful re-design of the programming interface and structure...

  13. Improvement for BWR operator training

    International Nuclear Information System (INIS)

    Kurisu, Takanori; Takahashi, Yoshitaka; Harada, Mitsuhiro; Takahashi, Iwao.

    1988-01-01

    BWR Operator Training Center was founded in April, 1971, and in April, 1974, training was begun, since then, 13 years elapsed. During this period, the curriculum and training facilities were strengthened to meet the training needs, and the new training techniques from different viewpoint were developed, thus the improvement of training has been done. In this report, a number of the training techniques which have been developed and adopted recently, and are effective for the improvement of the knowledge and skill of operators are described. Recently Japanese nuclear power stations have been operated at stable high capacity factor, accordingly the chance of experiencing the occurrence of abnormality and the usual start and stop of plants decreased, and the training of operators using simulators becomes more important. The basic concept on training is explained. In the standard training course and the short period fundamental course, the development of the guide for reviewing lessons, the utilization of VTRs and the development of the techniques for diagnosing individual degree of learning were carried out. The problems, the points of improvement and the results of these are reported. (Kako, I.)

  14. Reliability analysis of maintenance operations for railway tracks

    International Nuclear Information System (INIS)

    Rhayma, N.; Bressolette, Ph.; Breul, P.; Fogli, M.; Saussine, G.

    2013-01-01

    Railway engineering is confronted with problems due to degradation of the railway network that requires important and costly maintenance work. However, because of the lack of knowledge on the geometrical and mechanical parameters of the track, it is difficult to optimize the maintenance management. In this context, this paper presents a new methodology to analyze the behavior of railway tracks. It combines new diagnostic devices which permit to obtain an important amount of data and thus to make statistics on the geometric and mechanical parameters and a non-intrusive stochastic approach which can be coupled with any mechanical model. Numerical results show the possibilities of this methodology for reliability analysis of different maintenance operations. In the future this approach will give important informations to railway managers to optimize maintenance operations using a reliability analysis

  15. ADVANCED COMPRESSOR ENGINE CONTROLS TO ENHANCE OPERATION, RELIABILITY AND INTEGRITY

    Energy Technology Data Exchange (ETDEWEB)

    Gary D. Bourn; Jess W. Gingrich; Jack A. Smith

    2004-03-01

    This document is the final report for the ''Advanced Compressor Engine Controls to Enhance Operation, Reliability, and Integrity'' project. SwRI conducted this project for DOE in conjunction with Cooper Compression, under DOE contract number DE-FC26-03NT41859. This report addresses an investigation of engine controls for integral compressor engines and the development of control strategies that implement closed-loop NOX emissions feedback.

  16. Assessment of power reliability and improvement potential by using ...

    African Journals Online (AJOL)

    This paper presents the use of smart reclosers for improving reliability of a distribution system of one of the major cities of Ethiopia. As frequent power interruptions are posing a huge problem to the life of the people and the economy, finding a solution to the problem is very essential. Electric reliability has affected social well ...

  17. The operating reliability of the reactor coolant pump

    International Nuclear Information System (INIS)

    Grancy, W.

    1996-01-01

    There is a strong tendency among operating companies and manufacturers of nuclear power stations to further increase safety and operating availability of the plant and of its components. This applies also and particularly to reactor coolant pumps for the primary circuit of nuclear power stations of the type PWR. For 3 decades, ANDRITZ has developed and built such pumps and has attached great importance to the design of the complete pump rotor and of its essential surrounding elements, such as bearing and shaft seal. Apart from questions connected with design functioning of the pump there is one question of top priority: the operating reliability of the reactor coolant pump. The pump rotor (together with the rotor of the drive motor) is the only component within the primary system that permanently rotates at high speed during operation of the reactor plant. Many questions concerning design and configuration of such components cannot be answered purely theoretically, or they can only be answered partly. Therefore comprehensive development work and testing was necessary to increase the operating reliability of the pump rotor itself and of its surrounding elements. This contribution describes the current status of development and, as a focal point, discusses shaft sealing solutions elaborated so far. In this connection also a sealing system will be presented which aims for the first time at using a two-stage mechanical seal in reactor coolant pumps

  18. Modeling Optimal Scheduling for Pumping System to Minimize Operation Cost and Enhance Operation Reliability

    Directory of Open Access Journals (Sweden)

    Yin Luo

    2012-01-01

    Full Text Available Traditional pump scheduling models neglect the operation reliability which directly relates with the unscheduled maintenance cost and the wear cost during the operation. Just for this, based on the assumption that the vibration directly relates with the operation reliability and the degree of wear, it could express the operation reliability as the normalization of the vibration level. The characteristic of the vibration with the operation point was studied, it could be concluded that idealized flow versus vibration plot should be a distinct bathtub shape. There is a narrow sweet spot (80 to 100 percent BEP to obtain low vibration levels in this shape, and the vibration also follows similar law with the square of the rotation speed without resonance phenomena. Then, the operation reliability could be modeled as the function of the capacity and rotation speed of the pump and add this function to the traditional model to form the new. And contrast with the tradition method, the result shown that the new model could fix the result produced by the traditional, make the pump operate in low vibration, then the operation reliability could increase and the maintenance cost could decrease.

  19. Reliability of high-voltage pulse capacitors operating in large energy storages

    International Nuclear Information System (INIS)

    Kuchinskij, G.S.; Fedorova, V.S.; Shilin, O.V.

    1982-01-01

    To improve the reliability of pulse capacitors operating in capacitive energy storages, processes, resulting in break-down of capacitor insulation were investigated. A statistic model of failures was constructed and reliability of real capacitors, functioning at operating electric intensity Usub(oper) equal 70 kV/mm and at elevated intensity 90 kV/mm was calculated. Results of testing the IK50-ZU4 capacitor are given. The form of the capacitor service life distribution function was specified. To provide and confirm the assigned capacitor reliability, it is necessary to speed up tests at a higher voltage (1.3-1.5) Usub(oper). To improve the capacitor reliability, it is advisable to conduct acceptance tests, which include hold at increased constant voltage (1.3-1.5) Usub(oper) during 1-3 min and the effect of pulses of increased voltage (1.2-1.3) Usub(oper) with the pulse shape corresponding to operating conditions

  20. International cooperation - a way to improve reliability and safety

    International Nuclear Information System (INIS)

    John, A.

    1998-01-01

    The mission of the World Association of Nuclear Operators (WANO) is highlighted, and WANO's Peer Review programme is described. At the Dukovany nuclear power plant, a Peer Review was undertaken in December 1997. The results gave evidence of a good level of safety, reliability and culture of operation of the plant. (P.A.)

  1. Improving the reliability of fuel Enusa; Mejora de la fiabilidad del combustible en Enusa

    Energy Technology Data Exchange (ETDEWEB)

    Choithramani, S.; Quecedo, M.

    2015-07-01

    ENUSA is committed to providing our customers with fuel designs that meet their needs for operational efficiency, power, energy, performance and reliability. ENUSAs current fuel designs, covering BWR and PWR technologies, incorporate highest performance with proven reliability features developed along nuclear power operation history. As of January 2015, ENUSA has manufactured more than 20.000 fuel assemblies (around half BWR and half PWR), with operating conditions reflecting varying reactor power densities, cycle lengths, operating strategies and water chemistry environments. This experience brings the knowledge to model our fuel behavior and acts as the principal instrument to identify and characterize the failure mechanisms of our fuel. Based on the information obtained from all this years of operation, ENUSA has progressively developed and implemented numerous mitigating actions identified upon the knowledge on failure mechanisms, which are the bases for the fuel reliability improvement program. Contemporaneously to this implementation, a positive trend on ENUSA fuel reliability has been observed. (Author)

  2. Use of PRA methodology for enhancing operational safety and reliability

    International Nuclear Information System (INIS)

    Chu, B.; Rumble, E.; Najafi, B.; Putney, B.; Young, J.

    1985-01-01

    This paper describes a broad scope, on-going R and D study, sponsored by the Electric Power Research Institute (EPRI) to utilize key features of the state-of-the-art plant information management and system analysis techniques to develop and demonstrate a practical engineering tool for assisting plant engineering and operational staff to perform their activities more effectively. The study is foreseen to consist of two major activities: to develop a user-friendly, integrated software system; and to demonstrate the applications of this software on-site. This integrated software, Reliability Analysis Program with In-Plant Data (RAPID), will consist of three types of interrelated elements: an Executive Controller which will provide engineering and operations staff users with interface and control of the other two software elements, a Data Base Manager which can acquire, store, select, and transfer data, and Applications Modules which will perform the specific reliability-oriented functions. A broad range of these functions has been envisaged. The immediate emphasis will be focused on four application modules: a Plant Status Module, a Technical Specification Optimization Module, a Reliability Assessment Module, and a Utility Module for acquiring plant data

  3. Strategy for continuous improvement in IC manufacturability, yield, and reliability

    Science.gov (United States)

    Dreier, Dean J.; Berry, Mark; Schani, Phil; Phillips, Michael; Steinberg, Joe; DePinto, Gary

    1993-01-01

    Continual improvements in yield, reliability and manufacturability measure a fab and ultimately result in Total Customer Satisfaction. A new organizational and technical methodology for continuous defect reduction has been established in a formal feedback loop, which relies on yield and reliability, failed bit map analysis, analytical tools, inline monitoring, cross functional teams and a defect engineering group. The strategy requires the fastest detection, identification and implementation of possible corrective actions. Feedback cycle time is minimized at all points to improve yield and reliability and reduce costs, essential for competitiveness in the memory business. Payoff was a 9.4X reduction in defectivity and a 6.2X improvement in reliability of 256 K fast SRAMs over 20 months.

  4. Fuel R and D to improve fuel reliability

    International Nuclear Information System (INIS)

    Yang, Rosa; Cheng, Bo; Deshon, Jeff; Edsinger, Kurt; Ozer, Odelli

    2006-01-01

    Light water reactor fuel is operating in an increasingly challenging environment. Fuel burnup extension and cycle length increase both can increase the local duty. Reactor water chemistry modifications for the purpose of protection the plant system materials have the potential of increasing fuel surface deposition and cladding corrosion and hydriding. The status of fuel performance in US reactors is summarized and an update of the Fuel Reliability Program' established by the utility industry to ensure reliability is provided. (author)

  5. Operating reliability of the shaft seal system of ANDRITZ RCP

    International Nuclear Information System (INIS)

    Grancy, Werner; Zehentner, Martin

    2002-01-01

    The next generation of nuclear power stations will have to fulfil new expectations in terms of safety, operating behaviour and costs. This applies also and especially to reactor coolant pumps for the primary circuit of pressurized water reactor type nuclear power plants (RCP). For 4 decades, ANDRITZ AG has developed and built RCPs and has attached great importance to the design of the complete pump rotor and of its essential surrounding elements, such as e. g. the shaft seal. Many questions concerning design and configuration of the shaft seal system cannot be answered purely theoretically, or they can only be answered partly. Therefore, comprehensive development work and testing was necessary to increase the operating reliability of the seal. Apart from all relevant questions connected with design and functioning of the pump there is one question of top priority: the operating reliability of the shaft seal system. Therefore it is intended to describe the current status of design and development of ANDRITZ RCP for future Korean NPPs, to present the most important design features and to give an introduction concerning experiences for a 3-stage-hydrodynamic seal as well as for a 2-stage-hydrodynamic seal

  6. 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.

  7. Improving reliability in south Ajax with IntelliTEAM

    Energy Technology Data Exchange (ETDEWEB)

    Starck, A.P. [Veridian Connections Inc., Ajax, ON (Canada)

    2010-07-01

    Veridian Connections Incorporated is a local electricity distribution company in Ontario that is faced with end of life feeder cables and an aging system. Most of the feeders are combined overhead and underground cables supplied from several substations with a limited transfer capability. The commercial activity in the utility's service area is intolerant to sustained outages. Although the initial plan was to replace the cables, capital and time constraints led the utility to chose the IntelliTEAM 2 system to improve reliability, by reducing the frequency, duration and impact of outages. The unique system is based on submersible switchgear, PulseClosing and includes the substation breakers as IntelliTEAM devices. The current plan to implement a smart grid turns sustained outages into momentary outages; reduces the number of customers affected by a sustained failure; improves the ability to transfer loads; and reduces stresses on aged cables. The self healing system restores customers in less than a minute and provides visibility to SCADA operators through a high speed SpeedNet radio system. tabs., figs.

  8. Reliability improvement: where do we go from here

    International Nuclear Information System (INIS)

    Haueter, R.L.

    1976-01-01

    The present programs and the future plans in the area of power-plant productivity and reliability data collection and analyses are discussed. The shortcomings of the past industry efforts toward improving plant productivity are described, and some suggestions for improvement are presented

  9. Improving Reliability, Security, and Efficiency of Reconfigurable Hardware Systems (Habilitation)

    NARCIS (Netherlands)

    Ziener, Daniel

    2017-01-01

    In this treatise,  my research on methods to improve efficiency, reliability, and security of reconfigurable hardware systems, i.e., FPGAs, through partial dynamic reconfiguration is outlined. The efficiency of reconfigurable systems can be improved by loading optimized data paths on-the-fly on an

  10. Cost benefit justification of nuclear plant reliability improvement

    International Nuclear Information System (INIS)

    El-Sayed, M.A.H.; Abdelmonem, N.M.

    1986-01-01

    Nuclear power costs are evaluated on the bases of general ground rules (a) vary from time to time (b) vary from country to another (c) even vary from one reactor type to another. The main objective of an electric utility is to provide the electric energy to the different consummers at the lowest possible cost with reasonable reliability level. Rapid increase of the construction costs and fuel prices in recent years have stimulated a great deal of interest in improving the reliability and productivity of new and existing power plants. One of the most important areas is the improvement of the secondary steam loop and the reactor cooling system. The method for evaluating the reliability of steam loop and cooling system utilizes the cut-set technique. The developed method can be easily used to show to what extent the overall reliability of the nuclear plant is affected by the possible failures in the steam and cooling subsystem. The cost reliability trade-off analysis is used to evaluate alternative schemes in the design with a view towards meeting a high reliability goal. Based on historical or estimated failure and repair rate, the reliability of the alternate scheme can be calculated

  11. Improving the Reliability of Case-Based Reasoning Systems

    Directory of Open Access Journals (Sweden)

    Xu Xu

    2010-09-01

    also discussed in this paper, especially the property that whether inter-feature of case exists redundancy. After that, the reliability of an individual suggested solution is studied. To illustrate these ideas, some experiments and their results are discussed in this paper. The results of experiments show a new route concerning on how to improve the reliability of a CBR system at an overall level.

  12. Improvement in operators training for better performance of RAPS

    International Nuclear Information System (INIS)

    Banerjee, D.K.

    1989-01-01

    Nuclear Power Corporation (India) will need substantial number of technical personnel in the next couple of years to operate the new power plants. With number of stations coming up within a short span of time, standardisation of training, improved quality trainer, better technical support will be required to ensure reliable operation. (author)

  13. Application of reliability worth concepts in power system operational planning

    Energy Technology Data Exchange (ETDEWEB)

    Mello, J C.O. [Centro de Pesquisas de Energia Eletrica (CEPEL), Rio de Janeiro, RJ (Brazil); Silva, A.M. Leite da [Pontificia Univ. Catolica do Rio de Janeiro, RJ (Brazil); Pereira, M V.F. [Power System Research (PSR), Inc., Rio de Janeiro, RJ (Brazil)

    1994-12-31

    This work describes the application of a new methodology for calculating total system interruption costs in power system operational planning. Some important operational aspects are discussed: chronological load curves, customer damage functions for each consumer class, maintenance scheduling and non-exponential repair times. It is also presented the calculation of the probability distribution of the system interruption cost to improve the decision making process associated with alternative operational strategies. The Brazilian Southeastern system is used to illustrate all previous applications. (author) 24 refs., 8 figs., 4 tabs.

  14. 76 FR 23171 - Electric Reliability Organization Interpretations of Interconnection Reliability Operations and...

    Science.gov (United States)

    2011-04-26

    ... Reliability Standards for the Bulk-Power System, Order No. 693, FERC Stats. & Regs. ] 31,242, order on reh'g...-Power System reliability may request an interpretation of a Reliability Standard.\\7\\ The ERO's standards... information in its reliability assessments. The Reliability Coordinator must monitor Bulk Electric System...

  15. Equipment reliability improvement process; implementation in Almaraz NPP and Trillo NPP

    International Nuclear Information System (INIS)

    Risquez Bailon, Aranzazu; Gutierrez Fernandez, Eduardo

    2010-01-01

    The Equipment Reliability Improvement Process (INPO AP-913) is a non-regulatory process developed by the US Nuclear Industry for improving Plants Availability. This Process integrates and coordinates a broad range of equipment reliability activities into one process, performed by the Plant in a non-centralized way. The integration and coordination of these activities will allow plant personnel to evaluate the trends of important station equipment, develop and implement long-term equipment health plans, monitor equipment performance and condition, and make adjustments to preventive maintenance tasks and frequencies based on equipment operating experience, if necessary, arbitrating operational and design improvements, to reach a Failure-free Operation. This paper describes the methodology of Equipment Reliability Improvement Process, being focused on main aspects of the implementation process, relating to the scope and establishment of an Equipment Reliability Monitoring Plan, which should include and complement the existing mechanisms and organizations in the Plant to monitor the condition and performance of the equipments, with the common aim of achieving an operation free of failures. The paper will describe the tools that Iberdrola Ingenieria has developed to support the implementation and monitoring of the Equipment Reliability Improvement Process, as well as the results and lessons learned from its implementation in Almaraz NPP and Trillo NPP. (authors)

  16. Reliability analysis of operator's monitoring behavior in digital main control room of nuclear power plants and its application

    International Nuclear Information System (INIS)

    Zhang Li; Hu Hong; Li Pengcheng; Jiang Jianjun; Yi Cannan; Chen Qingqing

    2015-01-01

    In order to build a quantitative model to analyze operators' monitoring behavior reliability of digital main control room of nuclear power plants, based on the analysis of the design characteristics of digital main control room of a nuclear power plant and operator's monitoring behavior, and combining with operators' monitoring behavior process, monitoring behavior reliability was divided into three parts including information transfer reliability among screens, inside-screen information sampling reliability and information detection reliability. Quantitative calculation model of information transfer reliability among screens was established based on Senders's monitoring theory; the inside screen information sampling reliability model was established based on the allocation theory of attention resources; and considering the performance shaping factor causality, a fuzzy Bayesian method was presented to quantify information detection reliability and an example of application was given. The results show that the established model of monitoring behavior reliability gives an objective description for monitoring process, which can quantify the monitoring reliability and overcome the shortcomings of traditional methods. Therefore, it provides theoretical support for operator's monitoring behavior reliability analysis in digital main control room of nuclear power plants and improves the precision of human reliability analysis. (authors)

  17. Water chemistry - one of the key technologies for safe and reliable nuclear power plant operation

    International Nuclear Information System (INIS)

    Uchida, S.; Otoha, K.; Ishigure, K.

    2006-01-01

    Full text: Full text: Water chemistry control is one of the key technologies to establish safe and reliable operation of nuclear power plants. Continuous and collaborative efforts of plant manufacturers and plant operator utilities have been focused on optimal water chemistry control, for which, a trio of requirements for water chemistry, a) better reliability of reactor structures and fuels, b) lower occupational exposure, and c) fewer radwaste sources, should be simultaneously satisfied. The research committee related to water chemistry of the Atomic Energy Society of Japan has played important roles to enhance improvement in water chemistry control, to share knowledge and experience with water chemistry among plant operators and manufacturers, to establish common technological bases for plant water chemistry and then to transfer them to the next generation related to water chemistry. Furthermore, the committee has tried to contribute to arranging R and D proposals for further improvement in water chemistry control through road map planning

  18. Reliability database development and plant performance improvement effort at Korea Hydro and Nuclear Power Co

    International Nuclear Information System (INIS)

    Oh, S. J.; Hwang, S. W.; Na, J. H.; Lim, H. S.

    2008-01-01

    Nuclear utilities in recent years have focused on improved plant performance and equipment reliability. In U.S., there is a movement toward process integration. Examples are INPO AP-913 equipment reliability program and the standard nuclear performance model developed by NEI. Synergistic effect from an integrated approach can be far greater than as compared to individual effects from each program. In Korea, PSA for all Korean NPPs (Nuclear Power Plants) has been completed. Plant performance monitoring and improvement is an important goal for KHNP (Korea Hydro and Nuclear Power Company) and a risk monitoring system called RIMS has been developed for all nuclear plants. KHNP is in the process of voluntarily implementing maintenance rule program similar to that in U.S. In the future, KHNP would like to expand the effort to equipment reliability program and to achieve highest equipment reliability and improved plant performance. For improving equipment reliability, the current trend is moving toward preventive/predictive maintenance from corrective maintenance. With the emphasis on preventive maintenance, the failure cause and operation history and environment are important. Hence, the development of accurate reliability database is necessary. Furthermore, the database should be updated regularly and maintained as a living program to reflect the current status of equipment reliability. This paper examines the development of reliability database system and its application of maintenance optimization or Risk Informed Application (RIA). (authors)

  19. ICAROUS - Integrated Configurable Algorithms for Reliable Operations Of Unmanned Systems

    Science.gov (United States)

    Consiglio, María; Muñoz, César; Hagen, George; Narkawicz, Anthony; Balachandran, Swee

    2016-01-01

    NASA's Unmanned Aerial System (UAS) Traffic Management (UTM) project aims at enabling near-term, safe operations of small UAS vehicles in uncontrolled airspace, i.e., Class G airspace. A far-term goal of UTM research and development is to accommodate the expected rise in small UAS traffic density throughout the National Airspace System (NAS) at low altitudes for beyond visual line-of-sight operations. This paper describes a new capability referred to as ICAROUS (Integrated Configurable Algorithms for Reliable Operations of Unmanned Systems), which is being developed under the UTM project. ICAROUS is a software architecture comprised of highly assured algorithms for building safety-centric, autonomous, unmanned aircraft applications. Central to the development of the ICAROUS algorithms is the use of well-established formal methods to guarantee higher levels of safety assurance by monitoring and bounding the behavior of autonomous systems. The core autonomy-enabling capabilities in ICAROUS include constraint conformance monitoring and contingency control functions. ICAROUS also provides a highly configurable user interface that enables the modular integration of mission-specific software components.

  20. On Improving Reliability of SRAM-Based Physically Unclonable Functions

    Directory of Open Access Journals (Sweden)

    Arunkumar Vijayakumar

    2017-01-01

    Full Text Available Physically unclonable functions (PUFs have been touted for their inherent resistance to invasive attacks and low cost in providing a hardware root of trust for various security applications. SRAM PUFs in particular are popular in industry for key/ID generation. Due to intrinsic process variations, SRAM cells, ideally, tend to have the same start-up behavior. SRAM PUFs exploit this start-up behavior. Unfortunately, not all SRAM cells exhibit reliable start-up behavior due to noise susceptibility. Hence, design enhancements are needed for improving reliability. Some of the proposed enhancements in literature include fuzzy extraction, error-correcting codes and voting mechanisms. All enhancements involve a trade-off between area/power/performance overhead and PUF reliability. This paper presents a design enhancement technique for reliability that improves upon previous solutions. We present simulation results to quantify improvement in SRAM PUF reliability and efficiency. The proposed technique is shown to generate a 128-bit key in ≤0.2 μ s at an area estimate of 4538 μ m 2 with error rate as low as 10 − 6 for intrinsic error probability of 15%.

  1. Some approaches to system reliability improvement in engineering design

    International Nuclear Information System (INIS)

    Shen, Kecheng.

    1990-01-01

    In this thesis some approaches to system reliability improvement in engineering design are studied. In particular, the thesis aims at developing alternative methodologies for ranking of component importance which are more related to the design practice and which are more useful in system synthesis than the existing ones. It also aims at developing component reliability models by means of stress-strength interference which will enable both component reliability prediction and design for reliability. A new methodology for ranking of component importance is first developed based on the notion of the increase of the expected system yield. This methodology allows for incorporation of different improvement actions at the component level such as parallel redundancy, standby redundancy, burn-in, minimal repair and perfect replacement. For each of these improvement actions, the increase of system reliability is studied and used as the component importance measure. A possible connection between the commonly known models of component lifetimes and the stress-strength interference models is suggested. Under some general conditions the relationship between component failure rate and the stress and strength distribution characteristics is studied. A heuristic approach for obtaining bounds on failure probability through stress-strength interference is also presented. A case study and a worked example are presented, which illustrate and verify the developed importance measures and their applications in the analytical as well as synthetical work of engineering design. (author)

  2. Atomistic mechanisms of ReRAM cell operation and reliability

    Science.gov (United States)

    Pandey, Sumeet C.

    2018-01-01

    We present results from first-principles-based modeling that captures functionally important physical phenomena critical to cell materials selection, operation, and reliability for resistance-switching memory technologies. An atomic-scale description of retention, the low- and high-resistance states (RS), and the sources of intrinsic cell-level variability in ReRAM is discussed. Through the results obtained from density functional theory, non-equilibrium Green’s function, molecular dynamics, and kinetic Monte Carlo simulations; the role of variable-charge vacancy defects and metal impurities in determining the RS, the LRS-stability, and electron-conduction in such RS is reported. Although, the statistical electrical characteristics of the oxygen-vacancy (Ox-ReRAM) and conductive-bridging RAM (M-ReRAM) are notably different, the underlying similar electrochemical phenomena describing retention and formation/dissolution of RS are being discussed.

  3. Operational reliability of the Point Lepreau GS standby generators

    Energy Technology Data Exchange (ETDEWEB)

    Loughead, D. A.; McGregor, A. T. [Safety and Compllance Group, New Brunswick Electric Power Commission, Point Lepreau Generating Station, P.O.Box 10 Lepreau, New Brunswick E0G 2H0 (Canada)

    1986-02-15

    Performance of the two Point Lepreau GS standby generators during the first three years of licensed station operation is reviewed. It is shown that the mandated reliability/availability requirements have been met. The nature of starting and running failures has been examined and the consequences, in terms of design and procedural changes, discussed. A brief review of standby generator outages is included to permit estimates of standby generator availability and total Class III standby power unavailability. A pair of simple equations is introduced as a means of estimating the probable economic penalty, both cumulative and incremental, associated with the running failure of one standby generator while the other is on a maintenance outage. (authors)

  4. Operational reliability of the Point Lepreau GS standby generators

    International Nuclear Information System (INIS)

    Loughead, D.A.; McGregor, A.T.

    1986-01-01

    Performance of the two Point Lepreau GS standby generators during the first three years of licensed station operation is reviewed. It is shown that the mandated reliability/availability requirements have been met. The nature of starting and running failures has been examined and the consequences, in terms of design and procedural changes, discussed. A brief review of standby generator outages is included to permit estimates of standby generator availability and total Class III standby power unavailability. A pair of simple equations is introduced as a means of estimating the probable economic penalty, both cumulative and incremental, associated with the running failure of one standby generator while the other is on a maintenance outage. (authors)

  5. 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.)

  6. Improving Punctuality and Transfer Reliability by Railway Timetable Optimization

    NARCIS (Netherlands)

    Goverde, R.M.P.

    1999-01-01

    The Dutch railway network is operated close to capacity with the current safety system. This leaves little space for control by process operators by which a delayed train can cause severe delay propagation. The NS currently invest a large amount in punctuality improvement of the railway operations.

  7. Study on the improvement of nuclear fuel cladding reliability

    International Nuclear Information System (INIS)

    Rheem, Karp Soon; Han, Jung Ho; Jeong, Yong Hwan; Lee, Deok Hyun

    1987-12-01

    In order to improve the nuclear fuel cladding reliability for high burn-up fuels, the corrosion resistance of laser beam surface treated and β-quenched zircaloys and the mechanical characteristics including fatigue, burst, and out-of-pile PCMI characteristics of heat treated zircaloys were investigated. In addition, the inadiation characteristics of Ko-Ri reactor fuel claddings was examined. It was found that the wasteside corrosion resistance of commercial zircaloys was improved remarkably by laser beam surface treatment. The out-of-pile transient cladding failures were investigated in terms of hoop stress versus time-to-failures by means of mandrel loading units at 25 deg C and 325 deg C. Fatigue characteristics of the β-quenched and as-received zircaloy cladding were investigated by using an internal oil pressurization method which can simulate the load-following operation cycle. The results were in good agreement with the existing data obtained by conventional methods for commercial zircaloys. Burst tests were performed with commercial and the β-quenched zircaloys in high pressure argon gas atmosphere as a function of burst temperature. The burst stress decreased linearly in the α phase region up to 600 deg C and hereafter the decrement of the burst stress decreased gradually with temperature in the β-phase region. For the first time, the burst characteristic of the irradiated zircaloy-4 cladding tubes released from Ko-Ri nuclear power unit 1 was investigated, and attempts were made to trace the cause of cladding failures by examining the failed structure and fret marks by debris. (Author)

  8. Cryogenics system: strategy to achieve nominal performance and reliable operation

    CERN Document Server

    Bremer, J; Casas, J; Claudet, S; Delikaris, D; Delruelle, N; Ferlin, G; Fluder, C; Perin, A; Perinic, G; Pezzetti, M; Pirotte, O; Tavian, L; Wagner, U

    2012-01-01

    During the LHC operation in 2010 and 2011, the cryogenic system has achieved an availability level fulfilling the overall requirement. To reach this level, the cryogenic system has profited like many other beam-dependent systems from the reduced beam parameters. Therefore, impacts of some failures occurred during the LHC operation were mitigated by using the overcapacity margin, the existing built-in redundancy in between adjacent sector cryogenic plants and the "cannibalization" of spares on two idle cryogenic plants. These two first years of operation were also crucial to identify the weaknesses of the present cryogenic maintenance plan and new issues like SEUs. After the LS1, nominal beam parameters are expected and the mitigated measures will be less effective or not applicable at all. Consequently, a consolidation plan to improve the MTBF and the MTTR of the LHC cryogenic system is under definition. Concerning shutdown periods, the present cryogenic sectorization imposes some restrictions in the type of ...

  9. Cryogenics system: strategy to achieve nominal performance and reliable operation

    International Nuclear Information System (INIS)

    Bremer, J.; Brodzinski, K.; Casas, J.; Claudet, S.; Delikaris, D.; Delruelle, N.; Ferlin, G.; Fluder, C.; Perin, A.; Perinic, G.; Pezzetti, M.; Pirotte, O.; Tavian, L.; Wagner, U.

    2012-01-01

    During the LHC operation in 2010 and 2011, the cryogenic system has achieved an availability level fulfilling the overall requirement. To reach this level, the cryogenic system has profited like many other beam-dependent systems from the reduced beam parameters. Therefore, impacts of some failures occurred during the LHC operation were mitigated by using the over-capacity margin, the existing built-in redundancy in between adjacent sector cryogenic plants and the 'cannibalization' of spares on two idle cryogenic plants. These two first years of operation were also crucial to identify the weaknesses of the present cryogenic maintenance plan and new issues like SEUs. After the LS1, nominal beam parameters are expected and the mitigated measures will be less effective or not applicable at all. Consequently, a consolidation plan to improve the MTBF and the MTTR of the LHC cryogenic system is under definition. Concerning shutdown periods, the present cryogenic sectorization imposes some restrictions in the type of interventions (e.g. cryo-magnet removal) which can be done without affecting the operating conditions of the adjacent sector. This creates additional constrains and possible extra down-time in the schedule of the shutdowns including the hardware commissioning. This presentation focuses on the consolidation plan foreseen during the LS1 to improve the performance of the LHC cryogenic system in terms of availability and sectorization. (authors)

  10. 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)

  11. 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)

  12. The reliability of structural systems operating at high temperature: Replacing engineering judgement with operational experience

    International Nuclear Information System (INIS)

    Chevalier, M.J.; Smith, D.J.; Dean, D.W.

    2012-01-01

    Deterministic assessments are used to assess the integrity of structural systems operating at high temperature by providing a lower bound lifetime prediction, requiring considerable engineering judgement. However such a result may not satisfy the structural integrity assessment purpose if the results are overly conservative or conversely plant observations (such as failures) could undermine the assessment result if observed before the lower bound lifetime. This paper develops a reliability methodology for high temperature assessments and illustrates the impact and importance of managing the uncertainties within such an analysis. This is done by separating uncertainties into three classifications; aleatory uncertainty, quantifiable epistemic uncertainty and unquantifiable epistemic uncertainty. The result is a reliability model that can predict the behaviour of a structural system based upon plant observations, including failure and survival data. This can be used to reduce the over reliance upon engineering judgement which is prevalent in deterministic assessments. Highlights: ► Deterministic assessments are shown to be heavily reliant upon engineering judgment. ► Based upon the R5 procedure, a reliability model for a structural system is developed. ► Variables must be classified as either aleatory or epistemic to model their impact on reliability. ► Operation experience is then used to reduce reliance upon engineering judgment. ► This results in a model which can predict system behaviour and learn from operational experience.

  13. Reliability improvement of multiversion software by exchanging modules

    International Nuclear Information System (INIS)

    Shima, Kazuyuki; Matsumoto, Ken-ichi; Torii, Koji

    1996-01-01

    In this paper, we proposes a method to improve reliability of multiversion software. In CER proposed in, checkpoints are put in versions of program and errors of versions are detected and recovered at the checkpoints. It prevent versions from failing and improve the reliability of multiversion software. But it is point out that CER decreases the reliability of the multiversion software if the detection and recovery of errors are assumed to be able to fail. In the method proposed in this paper, versions of program are developed following the same module specifications. When failures of versions of program are detected, faulty modules are identified and replaced them to other modules. It create versions without faulty modules and improve the reliability of multiversion software. The failure probability of multiversion software is estimated to become about a hundredth of the failure probability by the proposed method where the failure probability of each version is 0.000698, the number of versions is 5 and the number of modules is 20. (author)

  14. 18 CFR 292.308 - Standards for operating reliability.

    Science.gov (United States)

    2010-04-01

    ... reliability. 292.308 Section 292.308 Conservation of Power and Water Resources FEDERAL ENERGY REGULATORY... SMALL POWER PRODUCTION AND COGENERATION Arrangements Between Electric Utilities and Qualifying... may establish reasonable standards to ensure system safety and reliability of interconnected...

  15. 78 FR 69018 - Improving the Resiliency of Mobile Wireless Communications Networks; Reliability and Continuity...

    Science.gov (United States)

    2013-11-18

    ... consumers value overall network reliability and quality in selecting mobile wireless service providers, they...-125] Improving the Resiliency of Mobile Wireless Communications Networks; Reliability and Continuity... (Reliability NOI) in 2011 to ``initiate a comprehensive examination of issues regarding the reliability...

  16. APPLICATION OF TRAVEL TIME RELIABILITY FOR PERFORMANCE ORIENTED OPERATIONAL PLANNING OF EXPRESSWAYS

    Science.gov (United States)

    Mehran, Babak; Nakamura, Hideki

    Evaluation of impacts of congestion improvement scheme s on travel time reliability is very significant for road authorities since travel time reliability repr esents operational performance of expressway segments. In this paper, a methodology is presented to estimate travel tim e reliability prior to implementation of congestion relief schemes based on travel time variation modeling as a function of demand, capacity, weather conditions and road accident s. For subject expressway segmen ts, traffic conditions are modeled over a whole year considering demand and capacity as random variables. Patterns of demand and capacity are generated for each five minute interval by appl ying Monte-Carlo simulation technique, and accidents are randomly generated based on a model that links acci dent rate to traffic conditions. A whole year analysis is performed by comparing de mand and available capacity for each scenario and queue length is estimated through shockwave analysis for each time in terval. Travel times are estimated from refined speed-flow relationships developed for intercity expressways and buffer time index is estimated consequently as a measure of travel time reliability. For validation, estimated reliability indices are compared with measured values from empirical data, and it is shown that the proposed method is suitable for operational evaluation and planning purposes.

  17. On modeling human reliability in space flights - Redundancy and recovery operations

    Science.gov (United States)

    Aarset, M.; Wright, J. F.

    The reliability of humans is of paramount importance to the safety of space flight systems. This paper describes why 'back-up' operators might not be the best solution, and in some cases, might even degrade system reliability. The problem associated with human redundancy calls for special treatment in reliability analyses. The concept of Standby Redundancy is adopted, and psychological and mathematical models are introduced to improve the way such problems can be estimated and handled. In the past, human reliability has practically been neglected in most reliability analyses, and, when included, the humans have been modeled as a component and treated numerically the way technical components are. This approach is not wrong in itself, but it may lead to systematic errors if too simple analogies from the technical domain are used in the modeling of human behavior. In this paper redundancy in a man-machine system will be addressed. It will be shown how simplification from the technical domain, when applied to human components of a system, may give non-conservative estimates of system reliability.

  18. Tandem accelerator operation and improvements

    International Nuclear Information System (INIS)

    Yang Bingfan; Zhang Canzhe; Qin Jiuchang; Hu Yueming; Zhang Guilian; Jiang Yongliang; Hou Deyi; Yang Weimin; Yang Zhiren; Su Shengyong; Kan Chaoxin; Liu Dezhong; Wang Liyong; Bao Yiwen; You Qubo; Yang Tao; Zhang Yan; Zhou Lipeng; Chai Shiqin; Wang Meiyan

    1998-01-01

    The scheduled operation of HI-13 tandem accelerator for various experiments was performed well in 1996 and 1997. The machine running time was 4600 h and 4182 h while the beam time was 3845 h and 3712 h in 1996 and 1997, respectively. The operation of HI-13 tandem accelerator is pretty well. The beam distribution with terminal voltage and the distribution of beam time with ion species are shown out. The development of accelerating tubes for HI-13 tandem is in progress

  19. Reliability improvement methods for sapphire fiber temperature sensors

    Science.gov (United States)

    Schietinger, C.; Adams, B.

    1991-08-01

    Mechanical, optical, electrical, and software design improvements can be brought to bear in the enhancement of fiber-optic sapphire-fiber temperature measurement tool reliability in harsh environments. The optical fiber thermometry (OFT) equipment discussed is used in numerous process industries and generally involves a sapphire sensor, an optical transmission cable, and a microprocessor-based signal analyzer. OFT technology incorporating sensors for corrosive environments, hybrid sensors, and two-wavelength measurements, are discussed.

  20. Monolithic QCL design approaches for improved reliability and affordability

    Science.gov (United States)

    Law, K. K.

    2013-12-01

    Many advances have been made recently in mid-wave infrared and long-wave infrared quantum cascade lasers (QCLs) technologies, and there is an increasing demand for these laser sources for ever expanding Naval, DoD and homeland security applications. We will discuss in this paper a portfolio of various Naval Air Warfare Weapons Division's current and future small business innovative research programs and efforts on significantly improving QCLs' performance, affordability, and reliability.

  1. 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.

  2. Reliability Improved Cooperative Communication over Wireless Sensor Networks

    Directory of Open Access Journals (Sweden)

    Zhuangbin Chen

    2017-10-01

    Full Text Available With the development of smart devices and connection technologies, Wireless Sensor Networks (WSNs are becoming increasingly intelligent. New or special functions can be obtained by receiving new versions of program codes to upgrade their software systems, forming the so-called smart Internet of Things (IoT. Due to the lossy property of wireless channels, data collection in WSNs still suffers from a long delay, high energy consumption, and many retransmissions. Thanks to wireless software-defined networks (WSDNs, software in sensors can now be updated to help them transmit data cooperatively, thereby achieving more reliable communication. In this paper, a Reliability Improved Cooperative Communication (RICC data collection scheme is proposed to improve the reliability of random-network-coding-based cooperative communications in multi-hop relay WSNs without reducing the network lifetime. In WSNs, sensors in different positions can have different numbers of packets to handle, resulting in the unbalanced energy consumption of the network. In particular, nodes in non-hotspot areas have up to 90% of their original energy remaining when the network dies. To efficiently use the residual energy, in RICC, high data transmission power is adopted in non-hotspot areas to achieve a higher reliability at the cost of large energy consumption, and relatively low transmission power is adopted in hotspot areas to maintain the long network lifetime. Therefore, high reliability and a long network lifetime can be obtained simultaneously. The simulation results show that compared with other scheme, RICC can reduce the end-to-end Message Fail delivering Ratio (MFR by 59.4%–62.8% under the same lifetime with a more balanced energy utilization.

  3. Improved FTA methodology and application to subsea pipeline reliability design.

    Science.gov (United States)

    Lin, Jing; Yuan, Yongbo; Zhang, Mingyuan

    2014-01-01

    An innovative logic tree, Failure Expansion Tree (FET), is proposed in this paper, which improves on traditional Fault Tree Analysis (FTA). It describes a different thinking approach for risk factor identification and reliability risk assessment. By providing a more comprehensive and objective methodology, the rather subjective nature of FTA node discovery is significantly reduced and the resulting mathematical calculations for quantitative analysis are greatly simplified. Applied to the Useful Life phase of a subsea pipeline engineering project, the approach provides a more structured analysis by constructing a tree following the laws of physics and geometry. Resulting improvements are summarized in comparison table form.

  4. Operational safety improvement in OPR 1000

    International Nuclear Information System (INIS)

    Jung, Y.-E.

    2005-01-01

    Nuclear power operating experience management might be an important factor for the operational safety improvement. KHNP's nuclear information management system, called KONIS receives, distributes and manages all nuclear information from domestic and foreign, especially operating experience. Ulchin 3 and 4, the first units of OPR 1000 series operates several organizations regarding management of operating experience e.g. specialist group program, various task forces, equipment specialist system for operator, etc. Peer review is another contribution for nuclear safety. (author)

  5. Grant Peer Review: Improving Inter-Rater Reliability with Training.

    Science.gov (United States)

    Sattler, David N; McKnight, Patrick E; Naney, Linda; Mathis, Randy

    2015-01-01

    This study developed and evaluated a brief training program for grant reviewers that aimed to increase inter-rater reliability, rating scale knowledge, and effort to read the grant review criteria. Enhancing reviewer training may improve the reliability and accuracy of research grant proposal scoring and funding recommendations. Seventy-five Public Health professors from U.S. research universities watched the training video we produced and assigned scores to the National Institutes of Health scoring criteria proposal summary descriptions. For both novice and experienced reviewers, the training video increased scoring accuracy (the percentage of scores that reflect the true rating scale values), inter-rater reliability, and the amount of time reading the review criteria compared to the no video condition. The increase in reliability for experienced reviewers is notable because it is commonly assumed that reviewers--especially those with experience--have good understanding of the grant review rating scale. The findings suggest that both experienced and novice reviewers who had not received the type of training developed in this study may not have appropriate understanding of the definitions and meaning for each value of the rating scale and that experienced reviewers may overestimate their knowledge of the rating scale. The results underscore the benefits of and need for specialized peer reviewer training.

  6. Managing the effects of aging and reliability improvement

    International Nuclear Information System (INIS)

    Hall, R.E.; Taylor, J.H.; Boccio, J.L.

    1987-01-01

    Over recent years the electric power generating community has acknowledged the importance of the aging process on plant safety and availability. To cope with time-dependent degradation phenomenon that can affect active as well as passive components and lead to unacceptable, unanticipated failures requires research into the mechanisms of the aging process, advances in productive methods for assessing the aging impact on risk and availability, and a better understanding of power plant operations so that strategies for defending against this pervasive stress can be developed. This paper discusses current research advances and presents a framework to aid in the systematic integration of these three needs. As such it is anchored to research being conducted at Brookhaven National Laboratory in the areas of plant aging, life extension, reliability, performance indication, and risk assessment. The current question facing the industry can be simply stated. ''How can an acceptable level of safety and availability be maintained throughout the operational life of a nuclear power plant?'' The complexity of this question indicates that managing aging effects must be a continuous, coordinated process integrated with day-to-day tactical plant operation decisions. This implies that aging and reliability programs must be systemic properties of an organization's management, and that research into aging technology must be closely linked

  7. Reliability improvement of wire bonds subjected to fatigue stresses.

    Science.gov (United States)

    Ravi, K. V.; Philofsky, E. M.

    1972-01-01

    The failure of wire bonds due to repeated flexure when semiconductor devices are operated in an on-off mode has been investigated. An accelerated fatigue testing apparatus was constructed and the major fatigue variables, aluminum alloy composition, and bonding mechanism, were tested. The data showed Al-1% Mg wires to exhibit superior fatigue characteristics compared to Al-1% Cu or Al-1% Si and ultrasonic bonding to be better than thermocompression bonding for fatigue resistance. Based on these results highly reliable devices were fabricated using Al-1% Mg wire with ultrasonic bonding which withstood 120,000 power cycles with no failures.

  8. Reliability improvement through alternative designs-A case study

    International Nuclear Information System (INIS)

    Kumar, Saurabh; Chattopadhyay, Gopi; Kumar, Uday

    2007-01-01

    In today's competitive world, reliability of equipment is extremely important to maintain quality and delivery deadlines. This is achieved by using proper maintenance and design changes for unreliable subsystems and components of a complex system. It is significant to develop a strategy for maintenance, replacement and design changes related to those subsystems and components. An analysis of down time along with causes is essential to identify the unreliable components and subsystems. This paper presents an analysis of failure data of solenoid coils of automatic internal grinding machine used in a bearing manufacturing plant. It analyses various replacement and change of design options such as introduction of pneumatic system in place of electromagnetic solenoids for improvement of reliability of the plunger movement mechanism

  9. Zero tolerance for failure. An AREVA initiative to improve reliability

    International Nuclear Information System (INIS)

    Lippert, Hans-Joachim; Gentet, Guy; Mollard, Pierre; Garner, Norman

    2010-01-01

    Significant improvements in fuel reliability have been realized over the past 2 decades, but total elimination of failures has remained elusive. Driving reliability to higher levels requires a philosophy that does not accept that even infrequent and isolated failures are inevitable - it was on this foundation that Areva's Zero Tolerance for Failure (ZTF) initiative was established. This is not in itself either a program or project, but a fundamental shift in the way of thinking about work according to the following four principles: - Failures are avoidable, - Zero failures are our goal, - We will respond rapidly to any failure, - We succeed when we fix failures in a way that precludes recurrence. The shift to a ZTF philosophy is a broad change in corporate culture that expands the concept of failure far beyond cases where fuel rod cladding integrity is breached. While this paper specifically illustrates the ways in which ZTF has shaped the company's response to enhancing fuel rod reliability, ZTF extends to any failures of fuel products to deliver expected levels of performance, manufacturing processes to meet specifications and high first-pass acceptance criteria, and beyond to error-free performance of engineering analyses and cycle design and licensing services. Application of ZTF to enhancing fuel reliability deploys efforts in the areas of manufacturing, human factors, design, R and D, processes and product strategy. In order to achieve the necessary improvements, a number of important actions have been initiated across regions and facilities. In addition to these global scale projects and measures, each region contributes by adopting measures which are relevant to its particular activities and market needs. (orig.)

  10. Improving the reliability of emergency diesel generators through sustained maintenance

    International Nuclear Information System (INIS)

    Reddy, R.

    2000-01-01

    In Nuclear Power Stations Emergency Diesel Generators are vital safety related equipment which ensures power supply to essential equipment during loss of power. In view of their importance Reliability of Diesel generators should be very high. Since these Diesel generators are standby equipment and operate only during demand or during surveillance checks, their demand failure probability should be very low and once they operate their operational availability should be very high. Madras Atomic Power Station at Kalpakkam, India consists two pressurised heavy water Reactors each rated at 220 MWe. To supply standby power each unit has two Diesel Generators of I 500 kW capacity each. The Diesel Engine is 16 cylinder 'V' type engine and is cranked by Air starting motor and is connected to generator whose rating at 100% load is 1500 KW. During commissioning and in the initial years of operation these Diesel Generators have encountered many problems. Major problem was Diesel Engine failing to start on demand. This was due to non engagement of air motor pinion with ring gear or continued engagement air motor even after the engine had picked up speed and failure of timer to initiate multiple starts after initial incomplete starts Apart from these there were problems like fuel oil leaks, high jacket water temperatures, low fuel oil pressure trips. Another major problem was with excitation system. How these problems were dealt with thereby reducing the demand failure probability and increasing the operational availability are discussed in this paper. (author)

  11. Operational experience, availability and reliability of nuclear power plants

    International Nuclear Information System (INIS)

    Kueffer, K.

    1981-01-01

    This lecture presents a survey on nuclear power production and plant performance in the Western World covering all reactor types and light-water reactors in particular and discusses key parameters such as load factors and non-availability analysis, outlines the main reasons for the reliable performance of Swiss nuclear power plants and explains the management function as applied at the Beznau Nuclear Power Station to ensure high power productivity and reliability. (orig./RW)

  12. The importance of the reliability study for the safety operation of chemical plants. Application in heavy water plants

    International Nuclear Information System (INIS)

    Dumitrescu, Maria; Lazar, Roxana Elena; Preda, Irina Aida; Stefanescu, Ioan

    1999-01-01

    Heavy water production in Romania is based on H 2 O-H 2 S isotopic exchange process followed by vacuum isotopic distillation. The heavy water plant are complex chemical systems, characterized by an ensemble of static and dynamic equipment, AMC components, enclosures. Such equipment must have a high degree of reliability, a maximum safety in technological operation and a high availability index. Safety, reliable and economical operation heavy water plants need to maintain the systems and the components at adequate levels of reliability. The paper is a synthesis of the qualitative and quantitative assessment reliability studies for heavy water plants. The operation analysis on subsystems, each subsystems being a well-defined unit, is required by the plant complexity. For each component the reliability indicators were estimated by parametric and non-parametric methods based on the plant operation data. Also, the reliability qualitative and quantitative assessment was done using the fault tree technique. For the dual temperature isotopic exchange plants the results indicate an increase of the MTBF after the first years of operation, illustrating both the operation experience increasing and maintenance improvement. Also a high degree of availability was illustrated by the reliability studies of the vacuum distillation plant. The establishment of the reliability characteristics for heavy water plant represents an important step, a guide for highlighting the elements and process liable to failure being at the same time a planning modality to correlate the control times with the maintenance operations. This is the way to minimise maintenance, control and costs. The main purpose of the reliability study was the safety increase of the plant operation and the support for decision making. (authors)

  13. 75 FR 71613 - Mandatory Reliability Standards for Interconnection Reliability Operating Limits

    Science.gov (United States)

    2010-11-24

    ... Interconnection to relieve overloads on the facilities modeled in the Interchange Distribution Calculator (IDC... for other SOLs. But the Functional Model assigns a much broader role to the reliability coordinator to...

  14. Improving the Reliability of LDP through the Divergence of Power Supply for LDP

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Bang Sil [KHNP CRI, Daejeon (Korea, Republic of)

    2016-10-15

    The representative operating systems are Large Display Panel (LDP), Operator Workstation (OWS), Computerized Procedure System (CPS). The LDP provides the information which is plant essential safety function, plant operating mode, the state of major operating variable and the important alarm to operator continuously. In case of malfunction and switchover fail of the inverter, it is possible to occur the power loss of LDP. The power of LDP and operator console workstation had been supplied by only 2 non-safety Power Line1/Power Line2 (P.L1/P.L2). This study mentioned the divergence of power for LDP as method of power loss caused by unreliability of inverter. Ultimately, LDP power line has been added, and then it is more improved on the safety of LDP operation than before. So Shin-Kori 3,4 can enhance the reliability and economic, safety of plant.

  15. Improvement of Steam Generator Reliability for GEN-IV SFR

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Seong O; Kim Se Yun; Kim, Seok Hoon; Eoh, Jae Hyuk; Lee, Hyeong Yeon; Choi, Byung Seon

    2005-11-15

    The R and D items performed in this study were selected from the R and D task of ' Reliability improvement of Steam Generator' of GEN-IV SFR Component Design and BOP. Since this project deals with one of the most important issues for a GEN-IV SFR system, it needs to enhance the domestic technical backgrounds associated with the corresponding R and D items even for a very short period by 2005. This study provides the R and D results for i) Development of assessment methodology for dissimilar metal weld and ii) Development of multi-dimensional simulation methodology for a SWR event in a SFR steam generator.

  16. Improvement of Steam Generator Reliability for GEN-IV SFR

    International Nuclear Information System (INIS)

    Kim, Seong O; Kim Se Yun; Kim, Seok Hoon; Eoh, Jae Hyuk; Lee, Hyeong Yeon; Choi, Byung Seon

    2005-11-01

    The R and D items performed in this study were selected from the R and D task of ' Reliability improvement of Steam Generator' of GEN-IV SFR Component Design and BOP. Since this project deals with one of the most important issues for a GEN-IV SFR system, it needs to enhance the domestic technical backgrounds associated with the corresponding R and D items even for a very short period by 2005. This study provides the R and D results for i) Development of assessment methodology for dissimilar metal weld and ii) Development of multi-dimensional simulation methodology for a SWR event in a SFR steam generator

  17. Reliability and Validity of Qualitative and Operational Research Paradigm

    Directory of Open Access Journals (Sweden)

    Muhammad Bashir

    2008-01-01

    Full Text Available Both qualitative and quantitative paradigms try to find the same result; the truth. Qualitative studies are tools used in understanding and describing the world of human experience. Since we maintain our humanity throughout the research process, it is largely impossible to escape the subjective experience, even for the most experienced of researchers. Reliability and Validity are the issue that has been described in great deal by advocates of quantitative researchers. The validity and the norms of rigor that are applied to quantitative research are not entirely applicable to qualitative research. Validity in qualitative research means the extent to which the data is plausible, credible and trustworthy; and thus can be defended when challenged. Reliability and validity remain appropriate concepts for attaining rigor in qualitative research. Qualitative researchers have to salvage responsibility for reliability and validity by implementing verification strategies integral and self-correcting during the conduct of inquiry itself. This ensures the attainment of rigor using strategies inherent within each qualitative design, and moves the responsibility for incorporating and maintaining reliability and validity from external reviewers’ judgments to the investigators themselves. There have different opinions on validity with some suggesting that the concepts of validity is incompatible with qualitative research and should be abandoned while others argue efforts should be made to ensure validity so as to lend credibility to the results. This paper is an attempt to clarify the meaning and use of reliability and validity in the qualitative research paradigm.

  18. Cost/worth assessment of reliability improvement in distribution networks by means of artificial intelligence

    Energy Technology Data Exchange (ETDEWEB)

    Bouhouras, Aggelos S.; Labridis, Dimitris P.; Bakirtzis, Anastasios G. [Power Systems Laboratory, Aristotle University of Thessaloniki, Dept. of Electrical and Computer Engineering, 54124 Thessaloniki (Greece)

    2010-06-15

    A major challenge for the power utilities today is to ensure a high level of reliability of supply to customers. Two main factors determine the feasibility of a project that improves the reliability of supply: the project cost (investment and operational) and the benefits that result from the implementation of the project. This paper examines the implementation of an Artificial Intelligence System in an urban distribution network, capable to locate and isolate short circuit faults in the feeder, thus accomplishing immediate restoration of electric supply to the customers. The paper describes the benefits of the project, which are supply reliability improvement and distribution network loss reduction through network reconfigurations. By comparison of the project benefits and costs the economic feasibility of such a project for an underground distribution feeder in Greece is demonstrated. (author)

  19. Reliability research to nuclear power plant operators based on several methods

    International Nuclear Information System (INIS)

    Fang Xiang; Li Fu; Zhao Bingquan

    2009-01-01

    The paper utilizes many kinds of international reliability research methods, and summarizes the review of reliability research of Chinese nuclear power plant operators in past over ten years based on the simulator platform of nuclear power plant. The paper shows the necessity and feasibility of the research to nuclear power plant operators from many angles including human cognition reliability, fuzzy mathematics model and psychological research model, etc. It will be good to the safe operation of nuclear power plant based on many kinds of research methods to the reliability research of nuclear power plant operators. (authors)

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

    Science.gov (United States)

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

    2018-01-01

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

  1. Revised scoring and improved reliability for the Communication Patterns Questionnaire.

    Science.gov (United States)

    Crenshaw, Alexander O; Christensen, Andrew; Baucom, Donald H; Epstein, Norman B; Baucom, Brian R W

    2017-07-01

    The Communication Patterns Questionnaire (CPQ; Christensen, 1987) is a widely used self-report measure of couple communication behavior and is well validated for assessing the demand/withdraw interaction pattern, which is a robust predictor of poor relationship and individual outcomes (Schrodt, Witt, & Shimkowski, 2014). However, no studies have examined the CPQ's factor structure using analytic techniques sufficient by modern standards, nor have any studies replicated the factor structure using additional samples. Further, the current scoring system uses fewer than half of the total items for its 4 subscales, despite the existence of unused items that have content conceptually consistent with those subscales. These characteristics of the CPQ have likely contributed to findings that subscale scores are often troubled by suboptimal psychometric properties such as low internal reliability (e.g., Christensen, Eldridge, Catta-Preta, Lim, & Santagata, 2006). The present study uses exploratory and confirmatory factor analyses on 4 samples to reexamine the factor structure of the CPQ to improve scale score reliability and to determine if including more items in the subscales is warranted. Results indicate that a 3-factor solution (constructive communication and 2 demand/withdraw scales) provides the best fit for the data. That factor structure was confirmed in the replication samples. Compared with the original scales, the revised scales include additional items that expand the conceptual range of the constructs, substantially improve reliability of scale scores, and demonstrate stronger associations with relationship satisfaction and sensitivity to change in therapy. Implications for research and treatment are discussed. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

  2. Evaluation of reliability assurance approaches to operational nuclear safety

    International Nuclear Information System (INIS)

    Mueller, C.J.; Bezella, W.A.

    1984-01-01

    This report discusses the results of research to evaluate existing and/or recommended safety/reliability assurance activities among nuclear and other high technology industries for potential nuclear industry implementation. Since the Three Mile Island (TMI) accident, there has been increased interest in the use of reliability programs (RP) to assure the performance of nuclear safety systems throughout the plant's lifetime. Recently, several Nuclear Regulatory Commission (NRC) task forces or safety issue review groups have recommended RPs for assuring the continuing safety of nuclear reactor plants. 18 references

  3. 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.

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

    International Nuclear Information System (INIS)

    Hannaman, G.W.; Singh, A.

    1992-01-01

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

  5. Operator reliability study for Probabilistic Safety Analysis of an operating research reactor

    International Nuclear Information System (INIS)

    Mohamed, F.; Hassan, A.; Yahaya, R.; Rahman, I.; Maskin, M.; Praktom, P.; Charlie, F.

    2015-01-01

    Highlights: • Human Reliability Analysis (HRA) for Level 1 Probabilistic Safety Analysis (PSA) is performed on research nuclear reactor. • Implemented qualitative HRA framework is addressed. • Human Failure Events of significant impact to the reactor safety are derived. - Abstract: A Level 1 Probabilistic Safety Analysis (PSA) for the TRIGA Mark II research reactor of Malaysian Nuclear Agency has been developed to evaluate the potential risk in its operation. In conjunction to this PSA development, Human Reliability Analysis (HRA) is performed in order to determine human contribution to the risk. The aim of this study is to qualitatively analyze human actions (HAs) involved in the operation of this reactor according to the qualitative part of the HRA framework for PSA which is namely the identification, qualitative screening and modeling of HAs. By performing this framework, Human Failure Events (HFEs) of significant impact to the reactor safety are systematically analyzed and incorporated into the PSA structure. A part of the findings in this study will become the input for the subsequent quantitative part of the HRA framework, i.e. the Human Error Probability (HEP) quantification

  6. Nuclear units operating improvement by using operating experience

    International Nuclear Information System (INIS)

    Rotaru, I.; Bilegan, I.C.

    1997-01-01

    The paper presents how the information experience can be used to improve the operation of nuclear units. This areas include the following items: conservative decision making; supervisory oversight; teamwork; control room distraction; communications; expectations and standards; operator training and fundamental knowledge, procedure quality and adherence; plant status awareness. For each of these topics, the information illustrate which are the principles, the lessons learned from operating experience and the most appropriate exemplifying documents. (authors)

  7. Water chemistry technology. One of the key technologies for safe and reliable nuclear power plant operation

    International Nuclear Information System (INIS)

    Uchida, Shunsuke; Katsumura, Yosuke

    2013-01-01

    Water chemistry control is one of the key technologies to establish safe and reliable operation of nuclear power plants. Continuous and collaborative efforts of plant manufacturers and plant operator utilities have been focused on optimal water chemistry control, for which, a trio of requirements for water chemistry should be simultaneously satisfied: (1) better reliability of reactor structures and fuel rods; (2) lower occupational exposure and (3) fewer radwaste sources. Various groups in academia have carried out basic research to support the technical bases of water chemistry in plants. The Research Committee on Water Chemistry of the Atomic Energy Society of Japan (AESJ), which has now been reorganized as the Division of Water Chemistry (DWC) of AESJ, has played important roles to promote improvements in water chemistry control, to share knowledge about and experiences with water chemistry control among plant operators and manufacturers and to establish common technological bases for plant water chemistry and then to transfer them to the next generation of plant workers engaged in water chemistry. Furthermore, the DWC has tried and succeeded arranging R and D proposals for further improvement in water chemistry control through roadmap planning. In the paper, major achievements in plant technologies and in basic research studies of water chemistry in Japan are reviewed. The contributions of the DWC to the long-term safe management of the damaged reactors at the Fukushima Daiichi Nuclear Power Plant until their decommissioning are introduced. (author)

  8. 76 FR 23470 - Version One Regional Reliability Standard for Transmission Operations

    Science.gov (United States)

    2011-04-27

    ...; Order No. 752] Version One Regional Reliability Standard for Transmission Operations AGENCY: Federal... Power Act, the Federal Energy Regulatory Commission approves regional Reliability Standard TOP-007-WECC... purpose of this regional Reliability Standard is to ensure that actual flows and associated scheduled...

  9. 75 FR 80391 - Electric Reliability Organization Interpretations of Interconnection Reliability Operations and...

    Science.gov (United States)

    2010-12-22

    ... transmission (G&T) cooperative or similar organization to accept compliance responsibility on behalf of its... be found on the Commission's Web site; see, e.g., the ``Quick Reference Guide for Paper Submissions... Electric Reliability Standards, Order No. 672, FERC Stats. & Regs. ] 31,204, order on reh'g, Order No. 672...

  10. Improved Reliability of SiC Pressure Sensors for Long Term High Temperature Applications

    Science.gov (United States)

    Okojie, R. S.; Nguyen, V.; Savrun, E.; Lukco, D.

    2011-01-01

    We report advancement in the reliability of silicon carbide pressure sensors operating at 600 C for extended periods. The large temporal drifts in zero pressure offset voltage at 600 C observed previously were significantly suppressed to allow improved reliable operation. This improvement was the result of further enhancement of the electrical and mechanical integrity of the bondpad/contact metallization, and the introduction of studded bump bonding on the pad. The stud bump contact promoted strong adhesion between the Au bond pad and the Au die-attach. The changes in the zero offset voltage and bridge resistance over time at temperature were explained by the microstructure and phase changes within the contact metallization, that were analyzed with Auger electron spectroscopy (AES) and field emission scanning electron microscopy (FE-SEM).

  11. Managing the effects of aging and reliability improvement

    International Nuclear Information System (INIS)

    Hall, R.E.; Gunther, W.; Boccio, J.L.

    1989-01-01

    Over recent years the electric power generating community has acknowledged the importance of the aging process on plant safety and availability. To cope with time-dependent degradation phenomena that can affect active as well as passive components and lead to unacceptable, unanticipated failures requires research into the mechanisms of the aging process, advances in predictive methods for assessing the aging impact on risk and availability, and a better understanding of power plant operations so that strategies for defending against this pervasive stress can be developed. This paper discusses current research advances and presents a framework to aid in the systematic integration of these three needs. It also discusses current research in the aging effect on electric components. As such it is anchored to research being conducted at Brookhaven National Laboratory in the areas of plant aging, life extension, reliability, performance indication, and risk assessment. (orig.)

  12. Managing the effects of aging and reliability improvement

    International Nuclear Information System (INIS)

    Hall, R.E.; Gunther, W.; Boccio, J.L.

    1988-01-01

    Over recent years the electric power generating community has acknowledged the importance of the aging process on plant safety and availability. To cope with time-dependent degradation phenomena that can affect active as well as passive components and lead to unacceptable, unanticipated failures requires research into the mechanisms of the aging process, advances in predictive methods for assessing the aging impact on risk and availability, and a better understanding of power plant operations so that strategies for defending against this pervasive stress can be developed. This paper discusses current research advances and presents a framework to aid in the systematic integration of these three needs. As such it is anchored to research being conducted at Brookhaven National laboratory in the areas of plant aging, life extension, reliability, performance indication, and risk assessment

  13. Improving the reliability of stator insulation system in rotating machines

    International Nuclear Information System (INIS)

    Gupta, G.K.; Sedding, H.G.; Culbert, I.M.

    1997-01-01

    Reliable performance of rotating machines, especially generators and primary heat transport pump motors, is critical to the efficient operation on nuclear stations. A significant number of premature machine failures have been attributed to the stator insulation problems. Ontario Hydro has attempted to assure the long term reliability of the insulation system in critical rotating machines through proper specifications and quality assurance tests for new machines and periodic on-line and off-line diagnostic tests on machines in service. The experience gained over the last twenty years is presented in this paper. Functional specifications have been developed for the insulation system in critical rotating machines based on engineering considerations and our past experience. These specifications include insulation stress, insulation resistance and polarization index, partial discharge levels, dissipation factor and tip up, AC and DC hipot tests. Voltage endurance tests are specified for groundwall insulation system of full size production coils and bars. For machines with multi-turn coils, turn insulation strength for fast fronted surges in specified and verified through tests on all coils in the factory and on samples of finished coils in the laboratory. Periodic on-line and off-line diagnostic tests were performed to assess the condition of the stator insulation system in machines in service. Partial discharges are measured on-line using several techniques to detect any excessive degradation of the insulation system in critical machines. Novel sensors have been developed and installed in several machines to facilitate measurements of partial discharges on operating machines. Several off-line tests are performed either to confirm the problems indicated by the on-line test or to assess the insulation system in machines which cannot be easily tested on-line. Experience with these tests, including their capabilities and limitations, are presented. (author)

  14. Study on evaluation of construction reliability for engineering project based on fuzzy language operator

    Science.gov (United States)

    Shi, Yu-Fang; Ma, Yi-Yi; Song, Ping-Ping

    2018-03-01

    System Reliability Theory is a research hotspot of management science and system engineering in recent years, and construction reliability is useful for quantitative evaluation of project management level. According to reliability theory and target system of engineering project management, the defination of construction reliability appears. Based on fuzzy mathematics theory and language operator, value space of construction reliability is divided into seven fuzzy subsets and correspondingly, seven membership function and fuzzy evaluation intervals are got with the operation of language operator, which provides the basis of corresponding method and parameter for the evaluation of construction reliability. This method is proved to be scientific and reasonable for construction condition and an useful attempt for theory and method research of engineering project system reliability.

  15. Reliable and Fault-Tolerant Software-Defined Network Operations Scheme for Remote 3D Printing

    Science.gov (United States)

    Kim, Dongkyun; Gil, Joon-Min

    2015-03-01

    The recent wide expansion of applicable three-dimensional (3D) printing and software-defined networking (SDN) technologies has led to a great deal of attention being focused on efficient remote control of manufacturing processes. SDN is a renowned paradigm for network softwarization, which has helped facilitate remote manufacturing in association with high network performance, since SDN is designed to control network paths and traffic flows, guaranteeing improved quality of services by obtaining network requests from end-applications on demand through the separated SDN controller or control plane. However, current SDN approaches are generally focused on the controls and automation of the networks, which indicates that there is a lack of management plane development designed for a reliable and fault-tolerant SDN environment. Therefore, in addition to the inherent advantage of SDN, this paper proposes a new software-defined network operations center (SD-NOC) architecture to strengthen the reliability and fault-tolerance of SDN in terms of network operations and management in particular. The cooperation and orchestration between SDN and SD-NOC are also introduced for the SDN failover processes based on four principal SDN breakdown scenarios derived from the failures of the controller, SDN nodes, and connected links. The abovementioned SDN troubles significantly reduce the network reachability to remote devices (e.g., 3D printers, super high-definition cameras, etc.) and the reliability of relevant control processes. Our performance consideration and analysis results show that the proposed scheme can shrink operations and management overheads of SDN, which leads to the enhancement of responsiveness and reliability of SDN for remote 3D printing and control processes.

  16. Strategy for establishing integrated l and c reliability of operating nuclear power plants in korea

    International Nuclear Information System (INIS)

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

    2008-01-01

    Korea hydro and nuclear power co. (KHNP) are in progress of developing a integrated I and C reliability establishing strategy for managing l and C obsolescence and phasing in new technology that both meets the needs of the fleet and captures the benefits of applying proven solutions to multiple plants, with reduced incremental costs. In view of this, we are developing I and C component management which covers major failure mode, symptom of performance degradation, condition-based or time-based preventive management (PM), monitoring, and failure finding and correction based on equipment reliability (ER). Furthermore, for the l and C system replacement management, we are in progress of 3-year-long I and C systems upgrade fundamental designing in developing the long-term major l and C systems implementation plan to improve plant operations, eliminate operator challenges, reduce maintenance costs, and cope with the challenges of component obsolescence. For accomplishing I and C digital upgrade in near future, we chose demonstration plant, Younggwang (YGN) unit 3 and 4 which are Korean Standard Nuclear Power Plant (KSNP). In this paper, we established the long term reliability strategy of I and C system based on ER in component replacement and furthermore I and C systems digital upgrade in system replacement. (authors)

  17. Improvement for BWR operator training, 3

    International Nuclear Information System (INIS)

    Noji, Kunio; Toeda, Susumu; Saito, Genhachi; Suzuki, Koichi

    1990-01-01

    BWR Operator Training Center Corporation (BTC) is conducting training for BWR plant operators using Full-scope Simulators. There are several courses for individual operators and one training course for shift crew (Family Training Course) in BTC. Family Training is carried out by all members of the operating shift-crew. BTC has made efforts to improve the Family Training in order to acquire more effective training results and contribute to up-grade team performance of all crews. This paper describes some items of our efforts towards Family Training improvement. (author)

  18. Improved reliability, maintainability and safety through elastomer upgrading

    International Nuclear Information System (INIS)

    Wensel, R.; Wittich, K.C.

    1995-01-01

    Equipment in nuclear plants has historically contained whatever elastomer each component supplier traditionally used for corresponding non-nuclear service. The resulting proliferation of elastomer compounds, many of which are far from optimal for the service conditions (e.g., pressure, temperature, radiation, etc.), has multiplied the costs to provide station reliability, maintainability and safety. Cost-effective improvements are being achieved in CANDU plants by upgrading and standardizing on a handful of high performing elastomer compounds. These upgraded materials offer significant gains in service life over the materials they replace (often by factors of 2 or more). This rationalization of elastomer compounds also facilitates the EQ process for safety-related equipment. Detailed test data on aging is currently being generated for these specific elastomers, encompassing the conditions and media (air, water, oil) common in CANDU service. Two key elements characterize this testing. First, each result is specific to the compound used in the test, and second, it is specific to the tested failure mode (e.g., compression set, extrusion, fracture, etc.). Having fewer, but more thoroughly tested compounds, avoids the penalty (associated with poorly characterized materials) of having to replace parts prematurely because of conservatism, while maintaining safe, reliable service. This paper provides an overview of this approach covering: the benefits of compound rationalization; and the how and why of establishing relevant failure criteria; appropriate quality assurance to maintain EQ; procurement, storage and handling guidelines; and monitoring and predicting in-service degradation. (author)

  19. Improving Electronic Sensor Reliability by Robust Outlier Screening

    Directory of Open Access Journals (Sweden)

    Federico Cuesta

    2013-10-01

    Full Text Available Electronic sensors are widely used in different application areas, and in some of them, such as automotive or medical equipment, they must perform with an extremely low defect rate. Increasing reliability is paramount. Outlier detection algorithms are a key component in screening latent defects and decreasing the number of customer quality incidents (CQIs. This paper focuses on new spatial algorithms (Good Die in a Bad Cluster with Statistical Bins (GDBC SB and Bad Bin in a Bad Cluster (BBBC and an advanced outlier screening method, called Robust Dynamic Part Averaging Testing (RDPAT, as well as two practical improvements, which significantly enhance existing algorithms. Those methods have been used in production in Freescale® Semiconductor probe factories around the world for several years. Moreover, a study was conducted with production data of 289,080 dice with 26 CQIs to determine and compare the efficiency and effectiveness of all these algorithms in identifying CQIs.

  20. Improving the reliability of fishery predictions under climate change

    DEFF Research Database (Denmark)

    Brander, Keith

    2015-01-01

    The increasing number of publications assessing impacts of climate change on marine ecosystems and fisheries attests to rising scientific and public interest. A selection of recent papers, dealing more with biological than social and economic aspects, is reviewed here, with particular attention...... to the reliability of projections of climate impacts on future fishery yields. The 2014 Intergovernmental Panel on Climate Change (IPCC) report expresses high confidence in projections that mid- and high-latitude fish catch potential will increase by 2050 and medium confidence that low-latitude catch potential...... understanding of climate impacts, such as how to improve coupled models from physics to fish and how to strengthen confidence in analysis of time series...

  1. NKA/KRU project on operator training, control room designing and human reliability. Summary report

    International Nuclear Information System (INIS)

    1981-06-01

    A Nordic integrated project on human reliability in the conditions of new advanced technology seeks to establish: - The actual repertoire of activities and tasks performed by the operating staff of a nuclear power plant and its dependence on the present and future levels of automation. - The knowledge required for these activities and appropriate means for training plant operators and for competence evaluation and retraining in coping with the rare events. - Models of human operator performance; how do operators read information and make decisions under normal and abnormal plant conditions and how does their performance depend upon control room design. - The typical limits of human capabilities and mechanisms of human errors as they are represented in existing records of incidents and accidents in industrial plants. - The use of process computers for improved design of data presentation and operator support systems, especially for disturbance analysis and diagnosis during infrequent plant disturbance. - Development of experimental techniques to validate research results and proposals for improved man/machine interfaces and other computer-based support systems. (EG)

  2. Surface Operations Systems Improve Airport Efficiency

    Science.gov (United States)

    2009-01-01

    With Small Business Innovation Research (SBIR) contracts from Ames Research Center, Mosaic ATM of Leesburg, Virginia created software to analyze surface operations at airports. Surface surveillance systems, which report locations every second for thousands of air and ground vehicles, generate massive amounts of data, making gathering and analyzing this information difficult. Mosaic?s Surface Operations Data Analysis and Adaptation (SODAA) tool is an off-line support tool that can analyze how well the airport surface operation is working and can help redesign procedures to improve operations. SODAA helps researchers pinpoint trends and correlations in vast amounts of recorded airport operations data.

  3. Improved radiograph measurement inter-observer reliability by use of statistical shape models

    Energy Technology Data Exchange (ETDEWEB)

    Pegg, E.C., E-mail: elise.pegg@ndorms.ox.ac.uk [University of Oxford, Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, Nuffield Orthopaedic Centre, Windmill Road, Oxford OX3 7LD (United Kingdom); Mellon, S.J., E-mail: stephen.mellon@ndorms.ox.ac.uk [University of Oxford, Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, Nuffield Orthopaedic Centre, Windmill Road, Oxford OX3 7LD (United Kingdom); Salmon, G. [University of Oxford, Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, Nuffield Orthopaedic Centre, Windmill Road, Oxford OX3 7LD (United Kingdom); Alvand, A., E-mail: abtin.alvand@ndorms.ox.ac.uk [University of Oxford, Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, Nuffield Orthopaedic Centre, Windmill Road, Oxford OX3 7LD (United Kingdom); Pandit, H., E-mail: hemant.pandit@ndorms.ox.ac.uk [University of Oxford, Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, Nuffield Orthopaedic Centre, Windmill Road, Oxford OX3 7LD (United Kingdom); Murray, D.W., E-mail: david.murray@ndorms.ox.ac.uk [University of Oxford, Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, Nuffield Orthopaedic Centre, Windmill Road, Oxford OX3 7LD (United Kingdom); Gill, H.S., E-mail: richie.gill@ndorms.ox.ac.uk [University of Oxford, Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, Nuffield Orthopaedic Centre, Windmill Road, Oxford OX3 7LD (United Kingdom)

    2012-10-15

    Pre- and post-operative radiographs of patients undergoing joint arthroplasty are often examined for a variety of purposes including preoperative planning and patient assessment. This work examines the feasibility of using active shape models (ASM) to semi-automate measurements from post-operative radiographs for the specific case of the Oxford™ Unicompartmental Knee. Measurements of the proximal tibia and the position of the tibial tray were made using the ASM model and manually. Data were obtained by four observers and one observer took four sets of measurements to allow assessment of the inter- and intra-observer reliability, respectively. The parameters measured were the tibial tray angle, the tray overhang, the tray size, the sagittal cut position, the resection level and the tibial width. Results demonstrated improved reliability (average of 27% and 11.2% increase for intra- and inter-reliability, respectively) and equivalent accuracy (p > 0.05 for compared data values) for all of the measurements using the ASM model, with the exception of the tray overhang (p = 0.0001). Less time (15 s) was required to take measurements using the ASM model compared with manual measurements, which was significant. These encouraging results indicate that semi-automated measurement techniques could improve the reliability of radiographic measurements.

  4. Improved radiograph measurement inter-observer reliability by use of statistical shape models

    International Nuclear Information System (INIS)

    Pegg, E.C.; Mellon, S.J.; Salmon, G.; Alvand, A.; Pandit, H.; Murray, D.W.; Gill, H.S.

    2012-01-01

    Pre- and post-operative radiographs of patients undergoing joint arthroplasty are often examined for a variety of purposes including preoperative planning and patient assessment. This work examines the feasibility of using active shape models (ASM) to semi-automate measurements from post-operative radiographs for the specific case of the Oxford™ Unicompartmental Knee. Measurements of the proximal tibia and the position of the tibial tray were made using the ASM model and manually. Data were obtained by four observers and one observer took four sets of measurements to allow assessment of the inter- and intra-observer reliability, respectively. The parameters measured were the tibial tray angle, the tray overhang, the tray size, the sagittal cut position, the resection level and the tibial width. Results demonstrated improved reliability (average of 27% and 11.2% increase for intra- and inter-reliability, respectively) and equivalent accuracy (p > 0.05 for compared data values) for all of the measurements using the ASM model, with the exception of the tray overhang (p = 0.0001). Less time (15 s) was required to take measurements using the ASM model compared with manual measurements, which was significant. These encouraging results indicate that semi-automated measurement techniques could improve the reliability of radiographic measurements

  5. Nuclear Power Plant Operator Reliability Research Based on Fuzzy Math

    Directory of Open Access Journals (Sweden)

    Fang Xiang

    2011-01-01

    Full Text Available This paper makes use of the concept and theory of fuzzy number in fuzzy mathematics, to research for the response time of operator in accident of Chinese nuclear power plant. Through the quantitative analysis for the performance shape factors (PSFs which influence the response time of operators, the formula of the operator response time is obtained based on the possibilistic fuzzy linear regression model which is used for the first time in this kind of research. The research result shows that the correct research method can be achieved through the analysis of the information from a small sample. This method breaks through the traditional research method and can be used not only for the reference to the safe operation of nuclear power plant, but also in other areas.

  6. Improving the reliability of nuclear reprocessing by application of computers and mathematical modelling

    International Nuclear Information System (INIS)

    Gabowitsch, E.; Trauboth, H.

    1982-01-01

    After a brief survey of the present and expected future state of nuclear energy utilization, which should demonstrate the significance of nuclear reprocessing, safety and reliability aspects of nuclear reprocessing plants (NRP) are considered. Then, the principal possibilities of modern computer technology including computer systems architecture and application-oriented software for improving the reliability and availability are outlined. In this context, two information systems being developed at the Nuclear Research Center Karlsruhe (KfK) are briefly described. For design evaluation of certain areas of a large NRP mathematical methods and computer-aided tools developed, used or being designed by KfK are discussed. In conclusion, future research to be pursued in information processing and applied mathematics in support of reliable operation of NRP's is proposed. (Auth.)

  7. Investigation of DC-DC Boost Converter for Reliability of Operational Planning

    DEFF Research Database (Denmark)

    Khazraj, Hesam; Ashouri, Mani; Silva, Filipe Miguel Faria da

    2018-01-01

    of the interests related to reliability is the power semiconductor switches, which are the most vulnerable elements. The failure of one-power switches can reduce the system reliability. Interleaved technique for DC-DC converters is a redundant strategy to improve the reliability, but at the cost of increasing...

  8. INPO's role in the improvement of nuclear plant safety and reliability

    International Nuclear Information System (INIS)

    Pate, Z.T.

    1985-01-01

    The Institute of Nuclear Power Operations (INPO) is a nonprofit, nongovernment corporation dedicated to promoting safe and reliable operation and quality construction of nuclear power plants. The institute is supported by the US nuclear utility industry. All US utilities building or operating nuclear power plants are INPO members. INPO's many activities fall within four major program areas: (1) Evaluations: INPO conducts detailed evaluations of all US operating plants, utility corporate support of nuclear programs, and nuclear projects under active construction. Events analysis and information exchange: INPO reviews plant reports of abnormal or unusual events and reports the lessons learned to the industry. INPO also fosters improved industry communications through a worldwide telecommunications network. (3) Training and accreditation: INPO assists utilities, including international participants, in developing quality training programs; and (4) Assistance: the Institute provides various forms of assistance to members and participants. INPO places emphasis on visits to facilities to aid members and participants in various program or operational areas

  9. Advancements in valve technology and industry lessons lead to improved plant reliability and cost savings

    International Nuclear Information System (INIS)

    Sharma, V.; Kalsi, M.S.

    2005-01-01

    effort to be focused on those valves that are more likely to degrade prematurely. Leveraging state-of-the-art valve technologies such as these can enable nuclear power plants to improve safety and reliability, and reduce costs associated with maintenance and operation of the plants. (authors)

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

    International Nuclear Information System (INIS)

    Soszynska, Joanna

    2010-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2010-02-15

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

  12. Lecture 8: Data Reliability at CERN and Ideas on How to Improve it

    CERN Multimedia

    CERN. Geneva

    2013-01-01

    The talk will give an overview of data management activities at CERN focusing on the ongoing research activities aiming to improve data and service reliability. Alberto Pace is a member if the IT department at CERN where he leads the Data and Storage services group ensuring a coherent development process for Physics Data management activities, strongly driven by operational and user needs. He has more than 25 years experience in computing services, infrastructure, software engineering, accelerator control and accelerator operation. He graduated in Electronic Engineering from Politecnico di Milano (Italy).

  13. Verification and validation--The key to operating plant software reliability

    International Nuclear Information System (INIS)

    Daughtrey, H.T.; Daggett, P.W.; Schamp, C.A.

    1983-01-01

    This paper discusses the design and implementation of a verification and validation (V and V) plan for reviewing the microcomputer software developed for a Safety Parameter Display System (SPDS). Topics considered include a historical perspective on V and V, the function and significance of SPDS software, and testing. An SPDS provides information to nuclear power plant operators about the status of the plant under all operating conditions. It is determined that by implementing V and V activities throughout the development cycle, problems are less expensive to locate in the early phases of software development, problems are less expensive to fix in the early phases of software development, and a parallel V and V activity is more cost effective than a similar effort performed only at the end of software development. It is concluded that V and V is a proven tool for improving power plant software reliability

  14. Optimization of a PCRAM Chip for high-speed read and highly reliable reset operations

    Science.gov (United States)

    Li, Xiaoyun; Chen, Houpeng; Li, Xi; Wang, Qian; Fan, Xi; Hu, Jiajun; Lei, Yu; Zhang, Qi; Tian, Zhen; Song, Zhitang

    2016-10-01

    The widely used traditional Flash memory suffers from its performance limits such as its serious crosstalk problems, and increasing complexity of floating gate scaling. Phase change random access memory (PCRAM) becomes one of the most potential nonvolatile memories among the new memory techniques. In this paper, a 1M-bit PCRAM chip is designed based on the SMIC 40nm CMOS technology. Focusing on the read and write performance, two new circuits with high-speed read operation and highly reliable reset operation are proposed. The high-speed read circuit effectively reduces the reading time from 74ns to 40ns. The double-mode reset circuit improves the chip yield. This 1M-bit PCRAM chip has been simulated on cadence. After layout design is completed, the chip will be taped out for post-test.

  15. Nuclear power operating experience and technical improvement in Japan

    International Nuclear Information System (INIS)

    Toyota, M.

    1983-01-01

    LWR technology in Japan, originally introduced from the United States of America, is now almost entirely supplied domestically. During the initial stage of plant operation, electric power companies experienced various troubles such as intergranular stress corrosion cracking (IGSCC) in the piping in BWRs and steam generator (S/G) tube leaks in PWRs, which once reduced the capacity factor to about 40%. As a result of efforts to investigate the causes of the troubles and to establish countermeasures, which were applied to the plants in operation and under construction for improvement, as well as to shorten the period of regular inspection and to extend the operation cycle, the capacity factor has been improved to 60% since 1980. In 1975 an LWR improvement and standardization programme was launched to aim at improvement of reliability and availability factor and reduction of occupational radiation exposure with the development of domestic technology based on construction and operating experience. The First Phase Programme, which ran from 1975 to 1977, established countermeasures to preclude these troubles and improved workability by enlargement of the containment vessel. The Second Phase Programme followed and ran until 1981. The major steps taken during this period include the adoption of new IGSCC-resistant material and improved core design for BWRs and the improvement of fuels and S/Gs for PWRs. With these improvements, the capacity factor is now expected to reach a 75% level and occupational radiation exposure should be reduced by 50%. A Third Phase Programme will centre on the test and development programme for advanced BWRs and PWRs now under way to further improve the availability factor and reliability while also minimizing radiation exposure. (author)

  16. Modelling ship operational reliability over a mission under regular inspections

    NARCIS (Netherlands)

    Christer, A.H.; Lee, S.K.

    1997-01-01

    A ship is required to operate for a fixed mission period. Should a critical item of equipment fail at sea, the ship is subject to a costly event with potentially high risk to ship and crew. Given warning of a pending defect, the ship can try to return to port under its own power and thus attempt to

  17. A BWR Safety and Operability Improvements

    International Nuclear Information System (INIS)

    Sawyer, Craig D.

    1993-01-01

    The A BWR is the culmination of 30 years of design, development and operating experience of BWRs around the world. It represents across the board improvements is safety, operation and maintenance practices (O and M), economics, radiation exposure and rad waste generation. More than ten years and $20m5 went into the design and development of its new features, and it is now under construction in Japan. This paper concentrates on the safety and operability improvements. In the safety area, more than a decade improvement in core damage frequency (CDFR) has been assessed by formal PIRA techniques, with CDFR less than 10 -6 /year. Severe accident mitigation has also been formally addressed in the design. Plant operations were simplified by incorporation of better materials, optimum use of redundancy in mechanical and electrical equipment so that on-line maintenance can be performed, by better arrangements which account for required maintenance practices, and by an advanced control room

  18. Time-dependent reliability analysis of nuclear reactor operators using probabilistic network models

    International Nuclear Information System (INIS)

    Oka, Y.; Miyata, K.; Kodaira, H.; Murakami, S.; Kondo, S.; Togo, Y.

    1987-01-01

    Human factors are very important for the reliability of a nuclear power plant. Human behavior has essentially a time-dependent nature. The details of thinking and decision making processes are important for detailed analysis of human reliability. They have, however, not been well considered by the conventional methods of human reliability analysis. The present paper describes the models for the time-dependent and detailed human reliability analysis. Recovery by an operator is taken into account and two-operators models are also presented

  19. An analysis of operational experience during low power and shutdown and a plan for addressing human reliability assessment issues

    International Nuclear Information System (INIS)

    Barriere, M.; Luckas, W.; Whitehead, D.; Ramey-Smith, A.

    1994-06-01

    Recent nuclear power plant events (e.g. Chernobyl, Diablo Canyon, and Vogtle) and US Nuclear Regulatory Commission (NRC) reports (e.g. NUREG-1449) have led to concerns regarding human reliability during low power and shutdown (LP ampersand S) conditions and limitations of human reliability analysis (HRA) methodologies in adequately representing the LP ampersand S environment. As a result of these concerns, the NRC initiated two parallel research projects to assess the influence of LP ampersand S conditions on human reliability through an analysis of operational experience at pressurized water reactors (PWRs) an boiling water reactors (BWRs). These research projects, performed by Brookhaven National Laboratory for PWRS, and Sandia National Laboratories for BWRs, identified unique aspects of human performance during LP ampersand S conditions and provided a program plan for research and development necessary to improve existing HRA methodologies. This report documents the results of the analysis of LP ampersand S operating experience and describes the improved HRA program plan

  20. Good performance in Japan is proof of continuing safety and reliability improvement practice

    International Nuclear Information System (INIS)

    Sumi, Y.

    1987-01-01

    Nuclear power is a vital energy supply source for both security and economy for such countries as Japan whose sources of energy are dependent on imported materials. This is the very reason why Japan gives her national priority to the improvement of nuclear power safety and reliability. As of the end of 1986, total nuclear power capacity owned and operated by private utility companies in Japan amounted to 24521 MW with 32 units sharing -- 19% of the total generating capacity. Moreover, during 1986 these units scored a remarkably high capacity factor of 76.2% and shared almost 28% of the nationwide electric power production, thereby contributing to a considerable saving of imported sources of energy. This outstanding record has been achieved by the parties concerned who dedicated themselves to furthering nuclear plant safety and reliability improvement. In this connection, this paper summarizes those key factors contributing to the good nuclear power plant performance of the Kansai Electric Power Company

  1. Human reliability assessment on the basis of operating experience

    International Nuclear Information System (INIS)

    Straeter, O.

    1997-01-01

    For development of methodology, available models for qualitative assessment of human errors (e.g. by Swain, Hacker, Rasmussen) and a variety of known systematic approaches for quantitiative assessment of inadequate human action (e.g. THERP, ASEP, HCR, SLIM) were taken as a basis to establish a job specification, which in turn was used for developing a method for acquisition, characterisation and evaluation of errors. This method encompasses the two processes of event analysis and event evaluation: The first step comprises analysis of events by analysis of information describing the conditions and scenarios of relevance to the inadequate human action examined. In addition to the description of process sequences, information is taken into account on possible conditions that may bring about failure. As an assessment of human reliability requires manifold approaches for evaluation, a connectionistic procedure was developed for evaluation of the compilation of events based on a debate about various approaches from the domain of artificial intelligence (AI). This procedure yields both qualitative and quantitative information through a homogenous approach. (orig./GL) [de

  2. Improving fMRI reliability in presurgical mapping for brain tumours.

    Science.gov (United States)

    Stevens, M Tynan R; Clarke, David B; Stroink, Gerhard; Beyea, Steven D; D'Arcy, Ryan Cn

    2016-03-01

    Functional MRI (fMRI) is becoming increasingly integrated into clinical practice for presurgical mapping. Current efforts are focused on validating data quality, with reliability being a major factor. In this paper, we demonstrate the utility of a recently developed approach that uses receiver operating characteristic-reliability (ROC-r) to: (1) identify reliable versus unreliable data sets; (2) automatically select processing options to enhance data quality; and (3) automatically select individualised thresholds for activation maps. Presurgical fMRI was conducted in 16 patients undergoing surgical treatment for brain tumours. Within-session test-retest fMRI was conducted, and ROC-reliability of the patient group was compared to a previous healthy control cohort. Individually optimised preprocessing pipelines were determined to improve reliability. Spatial correspondence was assessed by comparing the fMRI results to intraoperative cortical stimulation mapping, in terms of the distance to the nearest active fMRI voxel. The average ROC-r reliability for the patients was 0.58±0.03, as compared to 0.72±0.02 in healthy controls. For the patient group, this increased significantly to 0.65±0.02 by adopting optimised preprocessing pipelines. Co-localisation of the fMRI maps with cortical stimulation was significantly better for more reliable versus less reliable data sets (8.3±0.9 vs 29±3 mm, respectively). We demonstrated ROC-r analysis for identifying reliable fMRI data sets, choosing optimal postprocessing pipelines, and selecting patient-specific thresholds. Data sets with higher reliability also showed closer spatial correspondence to cortical stimulation. ROC-r can thus identify poor fMRI data at time of scanning, allowing for repeat scans when necessary. ROC-r analysis provides optimised and automated fMRI processing for improved presurgical mapping. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence

  3. Reliability evaluation of a port oil transportation system in variable operation conditions

    International Nuclear Information System (INIS)

    Soszynska, Joanna

    2006-01-01

    The semi-Markov model of the system operation processes is proposed and its selected parameters are determined. The series 'm out of k n ' multi-state system is considered and its reliability and risk characteristics are found. Next, the joint model of the system operation process and the system multi-state reliability and risk is constructed. Moreover, reliability and risk evaluation of the multi-state series 'm out of k n ' system in its operation process is applied to the port oil transportation system

  4. Reliability evaluation of a port oil transportation system in variable operation conditions

    Energy Technology Data Exchange (ETDEWEB)

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

    2006-04-15

    The semi-Markov model of the system operation processes is proposed and its selected parameters are determined. The series 'm out of k {sub n}' multi-state system is considered and its reliability and risk characteristics are found. Next, the joint model of the system operation process and the system multi-state reliability and risk is constructed. Moreover, reliability and risk evaluation of the multi-state series 'm out of k {sub n}' system in its operation process is applied to the port oil transportation system.

  5. Domestic manufacturing and reliability improvement of reactor water recirculation equipment

    International Nuclear Information System (INIS)

    Kobayashi, Hidekazu; Oi, Masao; Shida, Toichi; Yokomori, Takashi

    1982-01-01

    The reactor coolant recirculation system is one of the important systems to control the reactor output in BWR nuclear power plants. Its components require high reliability and maintainability as well as controllability. For many Japanese nuclear power plants, recirculation pumps, fluid couplings and others have been imported so far. Hitachi Ltd. has established a domestic manufacturing organization through the development and test of these equipment. The fundamental design conditions for these equipment are the improvement of the rate of utilization of plant facility, the capability to follow load, and output power stability. In this paper, the specifications, the investigation of moment of inertia and the design features of recirculation pumps, driving motors and variable frequency power supply systems are described. The paper also reports on the combination test implemented to evaluate the recirculation system. The combination test includes the test using water rheostat for the power source facility and the loading test for a recirculation pump. The application of those system equipment to an actual plant was analyzed and evaluated on a basis of the test data obtained. The result showed that the equipment can achieve the rate of change of reactor power of 30%/min. Those equipment have been employed for No. 2 reactor plant of the Fukushima No. 2 Nuclear Power Station, the Tokyo Electric Power Co., Inc. (Wakatsuki, Y.)

  6. Diversity combining in laser Doppler vibrometry for improved signal reliability

    International Nuclear Information System (INIS)

    Dräbenstedt, Alexander

    2014-01-01

    Because of the speckle nature of the light reflected from rough surfaces the signal quality of a vibrometer suffers from varying signal power. Deep signal outages manifest themselves as noise bursts and spikes in the demodulated velocity signal. Here we show that the signal quality of a single point vibrometer can be substantially improved by diversity reception. This concept is widely used in RF communication and can be transferred into optical interferometry. When two statistically independent measurement channels are available which measure the same motion on the same spot, the probability for both channels to see a signal drop-out at the same time is very low. We built a prototype instrument that uses polarization diversity to constitute two independent reception channels that are separately demodulated into velocity signals. Send and receive beams go through different parts of the aperture so that the beams can be spatially separated. The two velocity channels are mixed into one more reliable signal by a PC program in real time with the help of the signal power information. An algorithm has been developed that ensures a mixing of two or more channels with minimum resulting variance. The combination algorithm delivers also an equivalent signal power for the combined signal. The combined signal lacks the vast majority of spikes that are present in the raw signals and it extracts the true vibration information present in both channels. A statistical analysis shows that the probability for deep signal outages is largely decreased. A 60 fold improvement can be shown. The reduction of spikes and noise bursts reduces the noise in the spectral analysis of vibrations too. Over certain frequency bands a reduction of the noise density by a factor above 10 can be shown

  7. Aggregate assessments support improved operational decision making

    International Nuclear Information System (INIS)

    Bauer, R.

    2003-01-01

    At Darlington Nuclear aggregate assessment of plant conditions is carried out in support of Operational Decision Making. This paper discusses how aggregate assessments have been applied to Operator Workarounds leading to improved prioritisation and alignment of work programs in different departments. As well, aggregate assessment of plant and human performance factors has been carried out to identify criteria which support conservative decision making in the main control room during unit transients. (author)

  8. TrigDB for improving the reliability of the epicenter locations by considering the neighborhood station's trigger and cutting out of outliers in operation of Earthquake Early Warning System.

    Science.gov (United States)

    Chi, H. C.; Park, J. H.; Lim, I. S.; Seong, Y. J.

    2016-12-01

    TrigDB is initially developed for the discrimination of teleseismic-origin false alarm in the case with unreasonably associated triggers producing mis-located epicenters. We have applied TrigDB to the current EEWS(Earthquake Early Warning System) from 2014. During the early stage of testing EEWS from 2011, we adapted ElarmS from US Berkeley BSL to Korean seismic network and applied more than 5 years. We found out that the real-time testing results of EEWS in Korea showed that all events inside of seismic network with bigger than magnitude 3.0 were well detected. However, two events located at sea area gave false location results with magnitude over 4.0 due to the long period and relatively high amplitude signals related to the teleseismic waves or regional deep sources. These teleseismic-relevant false events were caused by logical co-relation during association procedure and the corresponding geometric distribution of associated stations is crescent-shaped. Seismic stations are not deployed uniformly, so the expected bias ratio varies with evaluated epicentral location. This ratio is calculated in advance and stored into database, called as TrigDB, for the discrimination of teleseismic-origin false alarm. We upgraded this method, so called `TrigDB back filling', updating location with supplementary association of stations comparing triggered times between sandwiched stations which was not associated previously based on predefined criteria such as travel-time. And we have tested a module to reject outlier trigger times by setting a criteria comparing statistical values(Sigma) to the triggered times. The criteria of cutting off the outlier is slightly slow to work until the number of stations more than 8, however, the result of location is very much improved.

  9. An accurate and efficient reliability-based design optimization using the second order reliability method and improved stability transformation method

    Science.gov (United States)

    Meng, Zeng; Yang, Dixiong; Zhou, Huanlin; Yu, Bo

    2018-05-01

    The first order reliability method has been extensively adopted for reliability-based design optimization (RBDO), but it shows inaccuracy in calculating the failure probability with highly nonlinear performance functions. Thus, the second order reliability method is required to evaluate the reliability accurately. However, its application for RBDO is quite challenge owing to the expensive computational cost incurred by the repeated reliability evaluation and Hessian calculation of probabilistic constraints. In this article, a new improved stability transformation method is proposed to search the most probable point efficiently, and the Hessian matrix is calculated by the symmetric rank-one update. The computational capability of the proposed method is illustrated and compared to the existing RBDO approaches through three mathematical and two engineering examples. The comparison results indicate that the proposed method is very efficient and accurate, providing an alternative tool for RBDO of engineering structures.

  10. Improving a Dental School's Clinic Operations Using Lean Process Improvement.

    Science.gov (United States)

    Robinson, Fonda G; Cunningham, Larry L; Turner, Sharon P; Lindroth, John; Ray, Deborah; Khan, Talib; Yates, Audrey

    2016-10-01

    The term "lean production," also known as "Lean," describes a process of operations management pioneered at the Toyota Motor Company that contributed significantly to the success of the company. Although developed by Toyota, the Lean process has been implemented at many other organizations, including those in health care, and should be considered by dental schools in evaluating their clinical operations. Lean combines engineering principles with operations management and improvement tools to optimize business and operating processes. One of the core concepts is relentless elimination of waste (non-value-added components of a process). Another key concept is utilization of individuals closest to the actual work to analyze and improve the process. When the medical center of the University of Kentucky adopted the Lean process for improving clinical operations, members of the College of Dentistry trained in the process applied the techniques to improve inefficient operations at the Walk-In Dental Clinic. The purpose of this project was to reduce patients' average in-the-door-to-out-the-door time from over four hours to three hours within 90 days. Achievement of this goal was realized by streamlining patient flow and strategically relocating key phases of the process. This initiative resulted in patient benefits such as shortening average in-the-door-to-out-the-door time by over an hour, improving satisfaction by 21%, and reducing negative comments by 24%, as well as providing opportunity to implement the electronic health record, improving teamwork, and enhancing educational experiences for students. These benefits were achieved while maintaining high-quality patient care with zero adverse outcomes during and two years following the process improvement project.

  11. Status of Siemens steam generator design and measures to assure continuous long-term reliable operation

    International Nuclear Information System (INIS)

    Hoch, G.

    1999-01-01

    Operating pressurized water reactors with U-tube steam generators have encountered difficulties with either one or a combination of inadequate material selection, poor design or manufacturing and an insufficient water chemistry control which resulted in excessive tube degradation. In contrast to the above mentioned problems, steam generators from Siemens/KWU are proving by operating experience that all measures undertaken at the design stage as well as during the operating and maintenance phase were effective enough to counteract any tube corrosion phenomena or other steam generator related problem. An Integrated Service Concept has been developed, applied and wherever necessary improved in order to ensure reliable steam generator operation. The performance of the steam generators is updated continuously, evaluated and implemented in lifetime databases. The main indicator for steam generator integrity are the results of the eddy current testing of the steam generator tubes. Tubes with indications are rated with lifetime threshold values and if necessary plugged, based on individual assessment criteria.(author)

  12. New Methods for Building-In and Improvement of Integrated Circuit Reliability

    NARCIS (Netherlands)

    van der Pol, J.A.; van der Pol, Jacob Antonius

    2000-01-01

    Over the past 30 years the reliability of semiconductor products has improved by a factor of 100 while at the same time the complexity of the circuits has increased by a factor 105. This 7-decade reliability improvement has been realised by implementing a sophisticated reliability assurance system

  13. Design improvements, construction and operating experience with BWRs in Japan

    International Nuclear Information System (INIS)

    Uchigasaki, G.; Yokomi, M.; Sasaki, M.; Aoki, R.; Hashimoto, H.

    1983-01-01

    (1) The first domestic-made 1100-MW(e) BWR in Japan commenced commercial operation in April 1982. The unit is the leading one of the subsequent three in Fukushima Daini nuclear power station owned by the Tokyo Electric Power Company Inc. (Tepco). Based on the accumulated construction and operation experience of 500-MW(e) and 800-MW(e) class BWRs, improvements in various aspects during both the design and construction stages were introduced in core and fuel design with advanced gadolinia distribution, reactor feedwater treatment technology for crud reduction, a radwaste island, control and instrumentation to cope with the lessons learned through Three Mile Island assessment etc. (2) Based on many operating experiences with BWRs, an improved BWR core, which has easier operability and higher load factor than the conventional core, has been developed. The characteristic of the improved core is ''axially two-zoned uranium enrichment distribution''; the enrichment of the upper part of the fuel is slightly higher than that of the lower part. Through the improved core it became possible to optimize the axial power flattening and core reactivity control separately by axial enrichment distribution and burnable poison content. The improved fuels were loaded into operating BWRs and successfully proved the performance by this experience. (3) To shorten annual outage time, to reduce radiation exposure, to save manpower, and to achieve high reliability and safety of inspection operation, the remote automatic service and inspection equipment were developed in Japan. This paper presents the concept, distinctive features, and actual operation experience of the automatic refuelling machine, control-rod drive (CRD) remote-handling machine, improved main steam line isolation plug, and the automated ultrasonic inspection system with a computerized data processing unit, which have been developed by Hitachi, Ltd. with excellent results. (author)

  14. Improving Inversions of the Overlap Operator

    International Nuclear Information System (INIS)

    Krieg, S.; Cundy, N.; Eshof, J. van den; Frommer, A.; Lippert, Th.; Schaefer, K.

    2005-01-01

    We present relaxation and preconditioning techniques which accelerate the inversion of the overlap operator by a factor of four on small lattices, with larger gains as the lattice size increases. These improvements can be used in both propagator calculations and dynamical simulations

  15. Improving Metrological Reliability of Information-Measuring Systems Using Mathematical Modeling of Their Metrological Characteristics

    Science.gov (United States)

    Kurnosov, R. Yu; Chernyshova, T. I.; Chernyshov, V. N.

    2018-05-01

    The algorithms for improving the metrological reliability of analogue blocks of measuring channels and information-measuring systems are developed. The proposed algorithms ensure the optimum values of their metrological reliability indices for a given analogue circuit block solution.

  16. Reliability data bank in electronics: ITALTEL experience over 10 years of operation

    International Nuclear Information System (INIS)

    Turconi, G.

    1986-01-01

    The purpose of this paper is to show the Italtel Reliability Data Bank experience in electronics after ten years from data bank creation. Technological evolution on systems and equipment have originated a reliability data bank evolution in order to maintain and improve its performances. This paper will describe the concepts employed to design the today data bank features enabling it to be an important Company tool for reliability activities. (orig.)

  17. Mission reliability of semi-Markov systems under generalized operational time requirements

    International Nuclear Information System (INIS)

    Wu, Xiaoyue; Hillston, Jane

    2015-01-01

    Mission reliability of a system depends on specific criteria for mission success. To evaluate the mission reliability of some mission systems that do not need to work normally for the whole mission time, two types of mission reliability for such systems are studied. The first type corresponds to the mission requirement that the system must remain operational continuously for a minimum time within the given mission time interval, while the second corresponds to the mission requirement that the total operational time of the system within the mission time window must be greater than a given value. Based on Markov renewal properties, matrix integral equations are derived for semi-Markov systems. Numerical algorithms and a simulation procedure are provided for both types of mission reliability. Two examples are used for illustration purposes. One is a one-unit repairable Markov system, and the other is a cold standby semi-Markov system consisting of two components. By the proposed approaches, the mission reliability of systems with time redundancy can be more precisely estimated to avoid possible unnecessary redundancy of system resources. - Highlights: • Two types of mission reliability under generalized requirements are defined. • Equations for both types of reliability are derived for semi-Markov systems. • Numerical methods are given for solving both types of reliability. • Simulation procedure is given for estimating both types of reliability. • Verification of the numerical methods is given by the results of simulation

  18. Improving human reliability through better nuclear power plant system design. Progress report

    International Nuclear Information System (INIS)

    Golay, M.W.

    1995-01-01

    The project on open-quotes Development of a Theory of the Dependence of Human Reliability upon System Designs as a Means of Improving Nuclear Power Plant Performanceclose quotes has been undertaken in order to address the important problem of human error in advanced nuclear power plant designs. Most of the creativity in formulating such concepts has focused upon improving the mechanical reliability of safety related plant systems. However, the lack of a mature theory has retarded similar progress in reducing the likely frequencies of human errors. The main design mechanism used to address this class of concerns has been to reduce or eliminate the human role in plant operations and accident response. The plan of work being pursued in this project is to perform a set of experiments involving human subject who are required to operate, diagnose and respond to changes in computer-simulated systems, relevant to those encountered in nuclear power plants. In the tests the systems are made to differ in complexity in a systematic manner. The computer program used to present the problems to be solved also records the response of the operator as it unfolds. Ultimately this computer is also to be used in compiling the results of the project. The work of this project is focused upon nuclear power plant applications. However, the persuasiveness of human errors in using all sorts of electromechanical machines gives it a much greater potential importance. Because of this we are attempting to pursue our work in a fashion permitting broad generalizations

  19. EPRI (Electric Power Research Institute) operator reliability experiments program - Training implications

    International Nuclear Information System (INIS)

    Joksimovich, V.; Spurgin, A.J.; Orvis, D.D.; Moieni, P.; Worledge, D.H.

    1990-01-01

    The primary purpose of the EPRI Operator Reliability Experiments (ORE) Program is to collect data for use in reliability and safety studies of nuclear power plant operation to more realistically take credit for operator performance in preventing core damage. The two objectives for fulfilling this purpose are: (1) to obtain quantitative/qualitative performance data on operating crew responses in the control room for potential accident sequences by using plant simulators, and (2) to test the Human Cognitive Reliability (HCR) correlation. This paper briefly discusses the background to this program, data collection and analysis, the results and quantitative/qualitative insights stemming from phase one which might be of interest to simulator operators and trainers

  20. Application of reliability centred maintenance to optimize operation and maintenance in nuclear power plants

    International Nuclear Information System (INIS)

    2007-05-01

    In order to increase Member States capabilities in utilizing good engineering and management practices the Agency has developed a series of Technical Documents (TECDOCs) to describe best practices and members experience in the application of them. This TECDOC describes the concept of Reliability Centred Maintenance (RCM) which is the term used to describe a systematic approach to the evaluation, design and development of cost effective maintenance programmes for plant and equipment. The concept has been in existence for over 25 years originating in the civil aviation sector. This TECDOC supplements previous IAEA publications on the subject and seeks to reflect members experience in the application of the principles involved. The process focuses on the functionality of the plant and equipment and the critical failure mechanisms that could result in the loss of functionality. When employed effectively the process can result in the elimination of unnecessary maintenance activities and the identification and introduction of measures to address deficiencies in the maintenance programme. Overall the process can result in higher levels of reliability for the plant and equipment at reduced cost and demands on finite maintenance resources. The application of the process requires interaction between the operators and the maintenance practitioners which is often lacking in traditional maintenance programmes. The imposition of this discipline produces the added benefit of improved information flows between the key players in plant and equipment management with the result that maintenance activities and operational practices are better informed. This publication was produced within IAEA programme on nuclear power plants operating performance and life cycle management

  1. Experience on operational safety improvement of control and operation support systems

    International Nuclear Information System (INIS)

    Itoh, N.; Nakagawa, T.; Mano, K.

    1988-01-01

    Japanese nuclear industry started in 1956 and about 30 years have passed since that time. Through these years, we have made a lot of efforts and developments in the field of Control and Instrumentation (C and I) system. The above 30 years and following years can be divided into four major periods. The first one is the period of research, the second of domestic production, the third of improvement, and the fourth of advancement. Improvements of C and I system, which we have made in those periods have made a great contribution to enhancement of reliability, availability and operability of nuclear power plants. Fig. 1 shows TEPCO's nuclear power plant (BWR) construction experience and technical trend of C and I system in Japan. This paper is to introduce the efforts and operational experience on control and operation support systems

  2. Improvement of rate of operation of LWRs, (2)

    International Nuclear Information System (INIS)

    Makiura, Ryutaro

    1978-01-01

    In the first part, the growing importance of improving the rate of operation of nuclear power plants is expressed in view of the big unit capacity of the present plants. The following parts of this report are devoted to the description of various measures for improving the reliability and the rate of operation of BWR plants from the standpoint of plant makers. The first subject is the early solution of ''singular troubles'', for example, the channel wear due to the oscillation of LPRM strings. The second subject is ''ordinary troubles'' such as valve leak and malfunction, deterioration of various parts, and vibration of pipes. The improvement of load factor is discussed in the third part in connection with the present efforts to abolish the PCIOMR operation and to employ the fine motion of control rod-driving mechanism. The final subject concerns with the efforts for shortening the time required for regular inspection. Review of inspection items and shortening of their required time, reduction of radiation exposure automated and remote-controlled operation, and intensive training of operators are the main subjects discussed here. (Aoki, K.)

  3. Operational indices of WWER-1000 fuel assemblies and their improvements

    International Nuclear Information System (INIS)

    Vasilchenko, I.; Demin, E.

    1994-01-01

    The most general design features of WWER-1000 fuel assembly are discussed. The following advantages of design are stated as well as their operational confirmation and occurrences: 1) 'packing' density (tight-lattice) of fuel rods within the fuel assemblies; 2) simple handling of fuel assemblies and its small vulnerability; 3) good conditions for coolant mixing; 4) protection of the absorber rods against coolant effect; 5) adaptability to manufacture that provides stable quality. The main operational indices gathered during a ten-year period (1982-1992) at 17 WWER-1000 units in Russia and Ukraine are outlined. Provisions for emergency protection reliability are described. Future directions to improve fuel economy and control rod operability are discussed. 1 fig

  4. Operational indices of WWER-1000 fuel assemblies and their improvements

    Energy Technology Data Exchange (ETDEWEB)

    Vasilchenko, I; Demin, E [Opytno-Konstruktorskoe Byuro Gidropress, Podol` sk (Russian Federation)

    1994-12-31

    The most general design features of WWER-1000 fuel assembly are discussed. The following advantages of design are stated as well as their operational confirmation and occurrences: (1) `packing` density (tight-lattice) of fuel rods within the fuel assemblies; (2) simple handling of fuel assemblies and its small vulnerability; (3) good conditions for coolant mixing; (4) protection of the absorber rods against coolant effect; (5) adaptability to manufacture that provides stable quality. The main operational indices gathered during a ten-year period (1982-1992) at 17 WWER-1000 units in Russia and Ukraine are outlined. Provisions for emergency protection reliability are described. Future directions to improve fuel economy and control rod operability are discussed. 1 fig.

  5. Inter-operator and inter-device agreement and reliability of the SEM Scanner.

    Science.gov (United States)

    Clendenin, Marta; Jaradeh, Kindah; Shamirian, Anasheh; Rhodes, Shannon L

    2015-02-01

    The SEM Scanner is a medical device designed for use by healthcare providers as part of pressure ulcer prevention programs. The objective of this study was to evaluate the inter-rater and inter-device agreement and reliability of the SEM Scanner. Thirty-one (31) volunteers free of pressure ulcers or broken skin at the sternum, sacrum, and heels were assessed with the SEM Scanner. Each of three operators utilized each of three devices to collect readings from four anatomical sites (sternum, sacrum, left and right heels) on each subject for a total of 108 readings per subject collected over approximately 30 min. For each combination of operator-device-anatomical site, three SEM readings were collected. Inter-operator and inter-device agreement and reliability were estimated. Over the course of this study, more than 3000 SEM Scanner readings were collected. Agreement between operators was good with mean differences ranging from -0.01 to 0.11. Inter-operator and inter-device reliability exceeded 0.80 at all anatomical sites assessed. The results of this study demonstrate the high reliability and good agreement of the SEM Scanner across different operators and different devices. Given the limitations of current methods to prevent and detect pressure ulcers, the SEM Scanner shows promise as an objective, reliable tool for assessing the presence or absence of pressure-induced tissue damage such as pressure ulcers. Copyright © 2015 Bruin Biometrics, LLC. Published by Elsevier Ltd.. All rights reserved.

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

    DEFF Research Database (Denmark)

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

    2016-01-01

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

  7. Development of a Reliability Program approach to assuring operational nuclear safety

    International Nuclear Information System (INIS)

    Mueller, C.J.; Bezella, W.A.

    1985-01-01

    A Reliability Program (RP) model based on proven reliability techniques used in other high technology industries is being formulated for potential application in the nuclear power industry. Research findings are discussed. The reliability methods employed under NASA and military direction, commercial airline and related FAA programs were surveyed with several reliability concepts (e.g., quantitative reliability goals, reliability centered maintenance) appearing to be directly transferable. Other tasks in the RP development effort involved the benchmarking and evaluation of the existing nuclear regulations and practices relevant to safety/reliability integration. A review of current risk-dominant issues was also conducted using results from existing probabilistic risk assessment studies. The ongoing RP development tasks have concentrated on defining a RP for the operating phase of a nuclear plant's lifecycle. The RP approach incorporates safety systems risk/reliability analysis and performance monitoring activities with dedicated tasks that integrate these activities with operating, surveillance, and maintenance of the plant. The detection, root-cause evaluation and before-the-fact correction of incipient or actual systems failures as a mechanism for maintaining plant safety is a major objective of the RP

  8. Evaluation and improvement in nondestructive examination (NDE) reliability for inservice inspection of light water reactors

    International Nuclear Information System (INIS)

    Doctor, S.R.; Andersen, E.S.; Bowey, R.E.; Diaz, A.A.; Good, M.S.; Heasler, P.G.; Hockey, R.L.; Simonen, F.A.; Spanner, J.C.; Taylor, T.T.; Vo, T.V.

    1991-01-01

    This program is intended to establish the effectiveness, reliability and adequacy of inservice inspection of reactor pressure vessels and primary piping systems and the impact of ISI reliability on system integrity. The objectives of the program include: (a) determine the effectiveness and reliability of ultrasonic inservice inspection (ISI) performed on commercial, light water reactor pressure vessels and piping; (b) recommend Code changes to the inspection procedures to improve the reliability of ISI; (c) using fracture mechanics analysis, determine the impact of NDE unreliability on system safety and determine the level of inspection reliability required to assure a suitably low failure probability; (d) evaluate the degree of reliability improvement which could be achieved using improved NDE techniques; and (e) based on importance of component to safety, material properties, service conditions, and NDE uncertainties, formulate improved inservice inspection criteria (including sampling plan, frequency, and reliability of inspection) for revisions to ASME Section XI and regulatory requirements needed to assure suitably low failure probabilities

  9. Improvement of AC motor reliability from technique standardization

    International Nuclear Information System (INIS)

    Muniz, P.R.; Faria, M.D.R.; Mendes, M.P.; Silva, J.N.; Dos Santos, J.D.

    2005-01-01

    The purpose of this paper is to explain the increase of reliability of motors serviced in the Electrical Maintenance Shop of Companhia Siderurgica de Tubarao by standardization of the technique based on Brazilian and International Standards, manufacturer's recommendations and the experience of the maintenance staff. (author)

  10. Improving Reliability and Durability of Efficient and Clean Energy Systems

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Prabhakar [Univ. of Connecticut, Storrs, CT (United States)

    2010-08-01

    Overall objective of the research program was to develop an in-depth understanding of the degradation processes in advanced electrochemical energy conversion systems. It was also the objective of the research program to transfer the technology to participating industries for implementation in manufacturing of cost effective and reliable integrated systems.

  11. Monitoring of operational reliability of safety-related I and C subsystems at the Dukovany NPP

    International Nuclear Information System (INIS)

    Fuchs, P.; Sagl, P.; Zlamal, P.

    2007-01-01

    First, the situation existing in the data base in 1999, i.e. before the monitoring and the operational reliability monitoring concept were introduced, is highlighted. The technique of data processing is described with focus on the assessment of the relevancy of the records, component failure rate monitoring, estimation of basic statistical parameters, evaluation of the feasibility of component failure (or failure latency) detection, assessment of the mean time to repair, FMEA of the basic components (relays end measuring chains) to establish spurious signals and dangerous failure ratio. The reliability assessment of the system functions is based on structural reliability calculations (common cause failures not included). The outcomes from the operational reliability monitoring are presented in the form of a representative set of data, graphic charts and results of system function reliability assessment. Prospects for upgrading the I and C operational reliability monitoring system to the benefit of NPP Dukovany operating economy (life cycle costs evaluation, spare parts planning, RCM application) are outlined. (author)

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2009-07-01

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

  13. MANAGING OPERATIONS IMPROVEMENT IN ROMANIAN PUBLIC SERVICES

    Directory of Open Access Journals (Sweden)

    BALOI IONUT-COSMIN

    2015-07-01

    Full Text Available This paper aims to develop a pleading for the transfer of best practices to improving the operational activity in the Romanian public institutions. The practice of implementation demonstrates that the perception of many executives in the Romanian private enterprises regarding the set of tools to improve processes and assimilation of lean philosophy is not a very favorable and encouraging one. It can be said that only some large enterprises had successfully introduced in their daily practice and organization the improvement principles, the operational optimization and the elimination of waste sources. In the SMEs, and especially in the services the experiences are isolated, but they have demonstrated the usefulness (the frequency of saving goals indicate, indeed, the need for proliferation of continuous improvement principles. Regarding the public organizations, the implementation of the new management system of designing and operating the current practices is pretty unknown, accepted at declarative level, but becomes, when is planned and implemented rather a burden on managers who should take on this challenge. Both in public management and private management, today the focus is on people and relationships (processes and projects, starting of course with the work organization. The good practices successfully proved in the private management in the recent decades are transferred today to public institutions; and the Romanian public organizations tend to adapt, also in terms of processes optimization. The study aims to analyze the functioning of the hypothetical management system of processes improvements, respectively the applying of lean tools and principles within the public Romanian institution. They are treated some dysfunctions observed within the process of understanding the utility aspects and throughout the assuming of operational improvement goals within these organizations. The qualitative observations, the critical interpretations and

  14. Reliability and efficiency upgrades of power systems operation by implementing intelligent electronic devices with synchrophasor measurement technology support

    Directory of Open Access Journals (Sweden)

    Mokeev Alexey

    2017-01-01

    Full Text Available This paper reviews issues of reliability and efficiency upgrades of power systems functions by means of a widespread implementation of intelligent electronic devices (IED in various purposes supporting synchrophasor measurement technology. Thus, such issues as IED’s operational analysis in the conditions of electromagnetic and electromechanical transient processes and synthesis of digital filters that improve static and dynamic responses of these devices play an important role in their development.

  15. Reliability and efficiency upgrades of power systems operation by implementing intelligent electronic devices with synchrophasor measurement technology support

    OpenAIRE

    Mokeev Alexey

    2017-01-01

    This paper reviews issues of reliability and efficiency upgrades of power systems functions by means of a widespread implementation of intelligent electronic devices (IED) in various purposes supporting synchrophasor measurement technology. Thus, such issues as IED’s operational analysis in the conditions of electromagnetic and electromechanical transient processes and synthesis of digital filters that improve static and dynamic responses of these devices play an important role in their devel...

  16. Performance of nuclear power plants and analysis of some factors affecting their operational reliability and economy

    International Nuclear Information System (INIS)

    Kozak, M.; Havel, S.

    1989-09-01

    In Czechoslovakia, there are eight WWER 440 type reactors in operation at present. Since their introduction into operation, nuclear power plants in Czechoslovakia have exhibited high reliability. In the paper, total parameters of reliability with an analysis of causes affecting negatively their annual utilization are presented. Existence of a computerized information system for acquisition, recording and evaluation of reliability-significant data from operation and its feedback to designers and manufacturers of nuclear power plant equipment and components is a basic requirement of a systematic assurance of the needed level of nuclear power plant reliability. The information system is used simultaneously also for realistic evaluation of aging of equipment and systems. Analysis of the state of equipment is important mainly in the final stage of the NPP during consideration of further extension of its service life. Environmental effects of the Czechoslovak NPPs are very low (favourable). It follows from comparison of annual dose equivalents of the Czechoslovak NPPs operational personnel with the foreign NPPs that the values recorded in Czechoslovakia belong to the lowest ones. In conclusion, some ways of assurance of operational safety and reliability of the Czechoslovak nuclear power plants including the role of the State regulatory body are briefly discussed. (author). 3 tabs

  17. Improved Reliability of Single-Phase PV Inverters by Limiting the Maximum Feed-in Power

    DEFF Research Database (Denmark)

    Yang, Yongheng; Wang, Huai; Blaabjerg, Frede

    2014-01-01

    Grid operation experiences have revealed the necessity to limit the maximum feed-in power from PV inverter systems under a high penetration scenario in order to avoid voltage and frequency instability issues. A Constant Power Generation (CPG) control method has been proposed at the inverter level...... devices, allowing a quantitative prediction of the power device lifetime. A study case on a 3 kW single-phase PV inverter has demonstrated the advantages of the CPG control in terms of improved reliability.......Grid operation experiences have revealed the necessity to limit the maximum feed-in power from PV inverter systems under a high penetration scenario in order to avoid voltage and frequency instability issues. A Constant Power Generation (CPG) control method has been proposed at the inverter level....... The CPG control strategy is activated only when the DC input power from PV panels exceeds a specific power limit. It enables to limit the maximum feed-in power to the electric grids and also to improve the utilization of PV inverters. As a further study, this paper investigates the reliability performance...

  18. Researching and improving the reliability of reactor protection system of Qinshan nuclear power plant

    International Nuclear Information System (INIS)

    Jiang Zuyue; Sheng Jiannan

    1997-01-01

    Due to the original design defects of the Reactor Protection System (RPS) of Qinshan Nuclear Power Plant, this system has brought about a number of reactor shutdown accidents and Engineered Safety Features (ESF) mis-activation events which have seriously endangered safe and steady operation of the nuclear power plant. So over three years have been spent on research on the reform of the original design on the premise that the general wiring of the system should remain the same and that the system size should also remain small to be contained in the original cabinets. The following improvements were made: (1) Increase the system's anti-disturbance capability. The system's zero volt bus floating designs were modified to surmount the disturbance resulting from the bad isolation performance of impedance-isolated amplifier; Double grounds have been added to logical modules to surmount the disturbance resulting from zero volt floating bus during the replacement of single module with two connectors; The opto-coupling circuit in its oscillation input stage of Engineered Safety Features have been improved to increase its reliability. (2)Modify to output activation part of the system. The new type of output relays were selected and the relay activation circuits were redesigned in which switcher activation mode is used instead of amplifier activation mode so as to increase the reliability of relay operation and reduce the power consumption; CMOS buffer gates in the input and output stage of the circuit were used to match TTL circuits to CMOS circuits of the system

  19. The Impact of Automation Reliability and Operator Fatigue on Performance and Reliance

    Science.gov (United States)

    2016-09-23

    Cummings et al., 2007). Automation designed to assist operators in overload situations may promote operator disengagement during periods of low...Calhoun et al., 2011). This testbed offers several tasks designed to emulate the cognitive demands that an operator managing multiple UAVs is likely...reliable (Cronbach’s α = 0.94) measure of affective and cognitive components of trust in automation. Items gauge confidence in an automation and

  20. Reliability Improved Design for a Safety System Channel

    International Nuclear Information System (INIS)

    Oh, Eung Se; Kim, Yun Goo

    2016-01-01

    Nowadays, these systems are implemented with a same platform type, such as a qualified programmable logic controller (PLC). The platform intensively uses digital communication with fiber-optic links to reduce cabling costs and to achieve effective signal isolation. These communication interface and redundancies within a channel increase the complexness of an overall system design. This paper proposes a simpler channel architecture design to reduce the complexity and to enhance overall channel reliability. Simplified safety channel configuration is proposed and the failure probabilities are compared with baseline safety channel configuration using an estimated generic value. The simplified channel configuration achieves 40 percent failure reduction compare to baseline safety channel configuration. If this configuration can be implemented within a processor module, overall safety channel reliability is increase and costs of fabrication and maintenance will be greatly reduced

  1. Reliability Improved Design for a Safety System Channel

    Energy Technology Data Exchange (ETDEWEB)

    Oh, Eung Se; Kim, Yun Goo [KHNP, Daejeon (Korea, Republic of)

    2016-05-15

    Nowadays, these systems are implemented with a same platform type, such as a qualified programmable logic controller (PLC). The platform intensively uses digital communication with fiber-optic links to reduce cabling costs and to achieve effective signal isolation. These communication interface and redundancies within a channel increase the complexness of an overall system design. This paper proposes a simpler channel architecture design to reduce the complexity and to enhance overall channel reliability. Simplified safety channel configuration is proposed and the failure probabilities are compared with baseline safety channel configuration using an estimated generic value. The simplified channel configuration achieves 40 percent failure reduction compare to baseline safety channel configuration. If this configuration can be implemented within a processor module, overall safety channel reliability is increase and costs of fabrication and maintenance will be greatly reduced.

  2. Equipment reliability process improvement and preventive maintenance optimization

    International Nuclear Information System (INIS)

    Darragi, M.; Georges, A.; Vaillancourt, R.; Komljenovic, D.; Croteau, M.

    2004-01-01

    The Gentilly-2 Nuclear Power Plant wants to optimize its preventive maintenance program through an Integrated Equipment Reliability Process. All equipment reliability related activities should be reviewed and optimized in a systematic approach especially for aging plants such as G2. This new approach has to be founded on best practices methods with the purpose of the rationalization of the preventive maintenance program and the performance monitoring of on-site systems, structures and components (SSC). A rational preventive maintenance strategy is based on optimized task scopes and frequencies depending on their applicability, critical effects on system safety and plant availability as well as cost-effectiveness. Preventive maintenance strategy efficiency is systematically monitored through degradation indicators. (author)

  3. Improving nuclear power plant safety through operator aids

    International Nuclear Information System (INIS)

    1987-12-01

    In October 1986, the IAEA convened a one-week Technical Committee Meeting on Improving Nuclear Power Plant Safety Through Operator Aids. The term ''operator aid'' or more formally ''operator support system'' refers to a class of devices designed to be added to a nuclear power plant control station to assist an operator in performing his job and thereby decrease the probability of operator error. The addition of a carefully planned and designed operator aid should result in an increase in nuclear power plant safety and reliability. Operator aids encompass a wide range of devices from the very simple, such as color coding a display to distinguish it out of a group of similar displays, to the very complex, such as a computer-generated video display which concentrates a number of scattered indicator readings located around a control room into a concise display in front of the operator. This report provides guidelines and information to help make a decision as to whether an operator aid is needed, what kinds of operator aids are available and whether it should be purchased or developed by the utility. In addition, a discussion is presented on advanced operator aids to provide information on what may become available in the future. The broad scope of these guidelines makes it most suitable for use by a multi-disciplinary team. The document consists of two parts. The recommendations and results of the meeting discussions are given in the first part. The second part is the annex where the papers presented at the Technical Committee Meeting are printed. A separate abstract was prepared for each of the 10 papers. Refs, figs and tabs

  4. Web server's reliability improvements using recurrent neural networks

    DEFF Research Database (Denmark)

    Madsen, Henrik; Albu, Rǎzvan-Daniel; Felea, Ioan

    2012-01-01

    In this paper we describe an interesting approach to error prediction illustrated by experimental results. The application consists of monitoring the activity for the web servers in order to collect the specific data. Predicting an error with severe consequences for the performance of a server (t...... usage, network usage and memory usage. We collect different data sets from monitoring the web server's activity and for each one we predict the server's reliability with the proposed recurrent neural network. © 2012 Taylor & Francis Group...

  5. Improving human reliability through better nuclear power plant system design: Program for advanced nuclear power studies

    International Nuclear Information System (INIS)

    Golay, M.W.

    1993-01-01

    The project on ''Development of a Theory of the Dependence of Human Reliability upon System Designs as a Means of Improving Nuclear Power Plant Performance'' was been undertaken in order to address the problem of human error in advanced nuclear power plant designs. Lack of a mature theory has retarded progress in reducing likely frequencies of human errors. Work being pursued in this project is to perform a set of experiments involving human subjects who are required to operate, diagnose and respond to changes in computer-simulated systems, relevant to those encountered in nuclear power plants, which are made to differ in complexity in a systematic manner. The computer program used to present the problems to be solved also records the response of the operator as it unfolds

  6. 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

  7. Multi-Objective Distribution Network Operation Based on Distributed Generation Optimal Placement Using New Antlion Optimizer Considering Reliability

    Directory of Open Access Journals (Sweden)

    KHANBABAZADEH Javad

    2016-10-01

    Full Text Available Distribution network designers and operators are trying to deliver electrical energy with high reliability and quality to their subscribers. Due to high losses in the distribution systems, using distributed generation can improves reliability, reduces losses and improves voltage profile of distribution network. Therefore, the choice of the location of these resources and also determining the amount of their generated power to maximize the benefits of this type of resource is an important issue which is discussed from different points of view today. In this paper, a new multi-objective optimal location and sizing of distributed generation resources is performed to maximize its benefits on the 33 bus distribution test network considering reliability and using a new Antlion Optimizer (ALO. The benefits for DG are considered as system losses reduction, system reliability improvement and benefits from the sale electricity and voltage profile improvement. For each of the mentioned benefits, the ALO algorithm is used to optimize the location and sizing of distributed generation resources. In order to verify the proposed approach, the obtained results have been analyzed and compared with the results of particle swarm optimization (PSO algorithm. The results show that the ALO has shown better performance in optimization problem solution versus PSO.

  8. Highly-reliable operation of 638-nm broad stripe laser diode with high wall-plug efficiency for display applications

    Science.gov (United States)

    Yagi, Tetsuya; Shimada, Naoyuki; Nishida, Takehiro; Mitsuyama, Hiroshi; Miyashita, Motoharu

    2013-03-01

    Laser based displays, as pico to cinema laser projectors have gathered much attention because of wide gamut, low power consumption, and so on. Laser light sources for the displays are operated mainly in CW, and heat management is one of the big issues. Therefore, highly efficient operation is necessitated. Also the light sources for the displays are requested to be highly reliable. 638 nm broad stripe laser diode (LD) was newly developed for high efficiency and highly reliable operation. An AlGaInP/GaAs red LD suffers from low wall plug efficiency (WPE) due to electron overflow from an active layer to a p-cladding layer. Large optical confinement factor (Γ) design with AlInP cladding layers is adopted to improve the WPE. The design has a disadvantage for reliable operation because the large Γ causes high optical density and brings a catastrophic optical degradation (COD) at a front facet. To overcome the disadvantage, a window-mirror structure is also adopted in the LD. The LD shows WPE of 35% at 25°C, highest record in the world, and highly stable operation at 35°C, 550 mW up to 8,000 hours without any catastrophic optical degradation.

  9. Reliability and safety program plan outline for the operational phase of a waste isolation facility

    International Nuclear Information System (INIS)

    Ammer, H.G.; Wood, D.E.

    1977-01-01

    A Reliability and Safety Program plan outline has been prepared for the operational phase of a Waste Isolation Facility. The program includes major functions of risk assessment, technical support activities, quality assurance, operational safety, configuration monitoring, reliability analysis and support and coordination meetings. Detailed activity or task descriptions are included for each function. Activities are time-phased and presented in the PERT format for scheduling and interactions. Task descriptions include manloading, travel, and computer time estimates to provide data for future costing. The program outlined here will be used to provide guidance from a reliability and safety standpoint to design, procurement, construction, and operation of repositories for nuclear waste. These repositories are to be constructed under the National Waste Terminal Storage program under the direction of the Office of Waste Isolation, Union Carbide Corp. Nuclear Division

  10. Operational safety system reliability. Progress report, November 15, 1975--May 14, 1976

    International Nuclear Information System (INIS)

    Hockenbury, R.W.; Yeater, M.L.

    1976-05-01

    The report describes the objectives and present status of a study concerning the operational reliability of nuclear power plants. The purpose of the study is to develop utilitarian models for use with the Liquid-Metal-Cooled Fast Breeder Reactor; initial testing of the formalism can be carried out with LWR operational data. Methods are being directed towards (1) day-to-day operation of the nuclear plant protection system and (2) to better understand the protection system sensor characteristics in order to anticipate off-normal conditions. The initial models now underway are based on moment-matching, confidence bounding, and convolution methods in the case of the protection system reliability, and for the sensor response function, a convolution of component reliability probability distributions and noise signatures

  11. Ensemble Streamflow Forecast Improvements in NYC's Operations Support Tool

    Science.gov (United States)

    Wang, L.; Weiss, W. J.; Porter, J.; Schaake, J. C.; Day, G. N.; Sheer, D. P.

    2013-12-01

    Like most other water supply utilities, New York City's Department of Environmental Protection (DEP) has operational challenges associated with drought and wet weather events. During drought conditions, DEP must maintain water supply reliability to 9 million customers as well as meet environmental release requirements downstream of its reservoirs. During and after wet weather events, DEP must maintain turbidity compliance in its unfiltered Catskill and Delaware reservoir systems and minimize spills to mitigate downstream flooding. Proactive reservoir management - such as release restrictions to prepare for a drought or preventative drawdown in advance of a large storm - can alleviate negative impacts associated with extreme events. It is important for water managers to understand the risks associated with proactive operations so unintended consequences such as endangering water supply reliability with excessive drawdown prior to a storm event are minimized. Probabilistic hydrologic forecasts are a critical tool in quantifying these risks and allow water managers to make more informed operational decisions. DEP has recently completed development of an Operations Support Tool (OST) that integrates ensemble streamflow forecasts, real-time observations, and a reservoir system operations model into a user-friendly graphical interface that allows its water managers to take robust and defensible proactive measures in the face of challenging system conditions. Since initial development of OST was first presented at the 2011 AGU Fall Meeting, significant improvements have been made to the forecast system. First, the monthly AR1 forecasts ('Hirsch method') were upgraded with a generalized linear model (GLM) utilizing historical daily correlations ('Extended Hirsch method' or 'eHirsch'). The development of eHirsch forecasts improved predictive skill over the Hirsch method in the first week to a month from the forecast date and produced more realistic hydrographs on the tail

  12. Engineering of electrical systems of nuclear power stations for improved reliability

    International Nuclear Information System (INIS)

    Narasinga Rao, S.N.; Ramanathan, K.; Choudhary, N.N.

    1977-01-01

    Operational problems experienced in electrical systems/equipment of the Tarapur Atomic Power Station (TAPS) and the Rajasthan Atomic Power Station (RAPS) and their solutions are dealt in detail. This experience has led to new design concepts which are being introduced for improved reliability in design of the Madras Atomic Power Project (MAPP) and the Narora Atomic Power Project (NAPP). Saline pollution on switchyard equipments was the major problem of the TAPS due to its coastal location. Saline pollution resulted in flash over of insulators and failure of clamps. The problem was solved by suitable changes in insulators, conductors, transformers, switches and arranging portable live line washing of the switchyard equipment. In MAPP which is also located on coast, an indoor switchyard is built. NAPP is located in a seismic zone, therefore, all equipment is specified for appropriate seismic duty. Various other improvements are described. (M.G.B.)

  13. Evaluating and improving nuclear power plant operating performance

    International Nuclear Information System (INIS)

    1999-07-01

    This report aims to provide the basis for improvements in the understanding of nuclear power plants operation and ideas for improving future productivity. The purpose of the project was to identify good practices of operating performance at a few of the world's most productive plants. This report was prepared through a series of consultants meetings, a specialists meeting and an Advisory Group meeting with participation of experts from 23 Member States. The report is based on self-assessment of half a dozen plants that have been chosen as representatives of different reactor types in as many different countries, and the views and assessment of the participants on good practices influencing plant performance. Three main areas that influence nuclear power plant availability and reliability were identified in the discussions: (1) management practices, (2) personnel characteristics, and (3) working practices. These areas cover causes influencing plant performance under plant management control. In each area the report describes factors or good practices that positively influence plant availability. The case studies, presented in annexes, contain the plant self-assessment of areas that influence their availability and reliability. Six plants are represented in the case studies: (1) Dukovany (WWER, 1760 MW) in the Czech Republic; (2) Blayais (PWR, 3640 MW) in France; (3) Paks (WWER, 1840 MW) in Hungary; (4) Wolsong 1 (PHWR, 600 MW) in the Republic of Korea; (5) Trillo 1 (PWR, 1066 MW) in Spain; and (6) Limerick (BWR, 2220 MW) in the United States of America

  14. Evaluating and improving nuclear power plant operating performance

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1999-07-01

    This report aims to provide the basis for improvements in the understanding of nuclear power plants operation and ideas for improving future productivity. The purpose of the project was to identify good practices of operating performance at a few of the world`s most productive plants. This report was prepared through a series of consultants meetings, a specialists meeting and an Advisory Group meeting with participation of experts from 23 Member States. The report is based on self-assessment of half a dozen plants that have been chosen as representatives of different reactor types in as many different countries, and the views and assessment of the participants on good practices influencing plant performance. Three main areas that influence nuclear power plant availability and reliability were identified in the discussions: (1) management practices, (2) personnel characteristics, and (3) working practices. These areas cover causes influencing plant performance under plant management control. In each area the report describes factors or good practices that positively influence plant availability. The case studies, presented in annexes, contain the plant self-assessment of areas that influence their availability and reliability. Six plants are represented in the case studies: (1) Dukovany (WWER, 1760 MW) in the Czech Republic; (2) Blayais (PWR, 3640 MW) in France; (3) Paks (WWER, 1840 MW) in Hungary; (4) Wolsong 1 (PHWR, 600 MW) in the Republic of Korea; (5) Trillo 1 (PWR, 1066 MW) in Spain; and (6) Limerick (BWR, 2220 MW) in the United States of America Figs, tabs

  15. Improving Stochastic Communication Network Performance: Reliability vs. Throughput

    Science.gov (United States)

    1991-12-01

    increased to one. 2) arc survivabil.. ities will be increased in increments of one tenths. and 3) the costs to increase- arc si’rvivabilities were equal and...This reliability value is leni used to maximize the associated expected flow. For Net work A. a bIdget of (8)() pro(duces a tradcoff point at (.58.37...Network B for a buidgel of 2000 which allows a nel \\\\ork relial)ilitv of one to be achieved and a bidget of 1200 which allows for ;, maximum 57

  16. Modulator reliability and bandwidth improvement: replacing tetrodes with MOSFETs

    International Nuclear Information System (INIS)

    Donaldson, A.R.

    1982-01-01

    Three types of power MOS field effect transistors were studied with the intent of replacing a parallel pair of vacuum tube tetrodes in a linear modulator. The tetrodes have the shortest lifetimes of any other tubes in the system. The FETs offer definite performance advantages when compared to bipolar transistors and definite cost advantages when compared to vacuum tubes. Replacement of the tetrodes does however require careful consideration of voltage, current and to a lesser extent bandwidth capability in order to enhance overall modulator reliability without compromising present performance

  17. Integrated Life Cycle Management: A Strategy for Plants to Extend Operating Lifetimes Safely with High Operational Reliability

    International Nuclear Information System (INIS)

    Esselman, Thomas; Bruck, Paul; Mengers, Charles

    2012-01-01

    Nuclear plant operators are studying the possibility of extending their existing generating facilities operating lifetime to 60 years and beyond. Many nuclear plants have been granted licenses to operate their facilities beyond the original 40 year term; however, in order to optimize the long term operating strategies, plant decision-makers need a consistent approach to support their options. This paper proposes a standard methodology to support effective decision-making for the long-term management of selected station assets. Methods detailed are intended to be used by nuclear plant site management, equipment reliability personnel, long term planners, capital asset planners, license renewal staff, and others that intend to look at operation between the current time and the end of operation. This methodology, named Integrated Life Cycle Management (ILCM), will provide a technical basis to assist decision makers regarding the timing of large capital investments required to get to the end of operation safely and with high plant reliability. ILCM seeks to identify end of life cycle failure probabilities for individual plant large capital assets and attendant costs associated with their refurbishment or replacement. It will provide a standard basis for evaluation of replacement and refurbishment options for these components. ILCM will also develop methods to integrate the individual assets over the entire plant thus assisting nuclear plant decision-makers in their facility long term operating strategies. (author)

  18. Applying franchising principles to improving water and sanitation services reliability

    CSIR Research Space (South Africa)

    Wall, K

    2008-11-01

    Full Text Available CSIR research has found that franchising partnerships could alleviate and address many challenges in the operation and maintenance of water services infrastructure. Franchising brings appropriate training to those on-site, and also offers backup off...

  19. Improving risk assessment by defining consistent and reliable system scenarios

    Directory of Open Access Journals (Sweden)

    B. Mazzorana

    2009-02-01

    Full Text Available During the entire procedure of risk assessment for hydrologic hazards, the selection of consistent and reliable scenarios, constructed in a strictly systematic way, is fundamental for the quality and reproducibility of the results. However, subjective assumptions on relevant impact variables such as sediment transport intensity on the system loading side and weak point response mechanisms repeatedly cause biases in the results, and consequently affect transparency and required quality standards. Furthermore, the system response of mitigation measures to extreme event loadings represents another key variable in hazard assessment, as well as the integral risk management including intervention planning. Formative Scenario Analysis, as a supplement to conventional risk assessment methods, is a technique to construct well-defined sets of assumptions to gain insight into a specific case and the potential system behaviour. By two case studies, carried out (1 to analyse sediment transport dynamics in a torrent section equipped with control measures, and (2 to identify hazards induced by woody debris transport at hydraulic weak points, the applicability of the Formative Scenario Analysis technique is presented. It is argued that during scenario planning in general and with respect to integral risk management in particular, Formative Scenario Analysis allows for the development of reliable and reproducible scenarios in order to design more specifically an application framework for the sustainable assessment of natural hazards impact. The overall aim is to optimise the hazard mapping and zoning procedure by methodologically integrating quantitative and qualitative knowledge.

  20. Role of recent research in improving check valve reliability at nuclear power plants

    International Nuclear Information System (INIS)

    Kalsi, M.S.; Horst, C.L.; Wang, J.K.; Sharma, V.

    1990-01-01

    Check valve failures at nuclear power plants in recent years have led to serious safety concerns, and caused extensive damage to other plant components which had a significant impact on plant availability. In order to understand the failure mechanism and improve the reliability of check valves, a systematic research effort was proposed by Kalsi Engineering, Inc. to U.S. Nuclear Regulatory Commission (NRC). The overall goal of the research was to develop models for predicting the performance and degradation of swing check valves in nuclear power plant systems so that appropriate preventive maintenance or design modifications can be performed to improve the reliability of check valves. Under Phase I of this research, a large matrix of tests was run with instrumented swing check valves to determine the stability of the disc under a variety of upstream flow disturbances, covering a wide range of disc stop positions and flow velocities in two different valve sizes. The goals of Phase II research were to develop predictive models which quantify the anticipated degradation of swing check valves that have flow disturbances closely upstream of the valve and are operating under flow velocities that do not result in full disc opening. This research allows the inspection/maintenance activities to be focussed on those check valves that are more likely to suffer premature degradation. The quantitative wear and fatigue prediction methodology can be used to develop a sound preventive maintenance program. The results of the research also show the improvements in check valve performance/reliability that can be achieved by certain modifications in the valve design

  1. Improving plant state information for better operational safety

    International Nuclear Information System (INIS)

    Girard, C.; Olivier, E.; Grimaldi, X.

    1994-01-01

    Nuclear Power Plant (NPP) safety is strongly dependent on components' reliability and particularly on plant state information reliability. This information, used by the plant operators in order to produce appropriate actions, have to be of a high degree of confidence, especially in accidental conditions where safety is threatened. In this perspective, FRAMATOME, EDF and CEA have started a joint research program to prospect different solutions aiming at a better reliability for critical information needed to safety operate the plant. This paper gives the main results of this program and describes the developments that have been made in order to assess reliability of different information systems used in a Nuclear Power Plant. (Author)

  2. Operational Impacts of Operating Reserve Demand Curves on Production Cost and Reliability: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Krad, Ibrahim; Ibanez, Eduardo; Ela, Erik; Gao, Wenzhong

    2015-10-27

    The electric power industry landscape is continually evolving. As emerging technologies such as wind, solar, electric vehicles, and energy storage systems become more cost-effective and present in the system, traditional power system operating strategies will need to be reevaluated. The presence of wind and solar generation (commonly referred to as variable generation) may result in an increase in the variability and uncertainty of the net load profile. One mechanism to mitigate this is to schedule and dispatch additional operating reserves. These operating reserves aim to ensure that there is enough capacity online in the system to account for the increased variability and uncertainty occurring at finer temporal resolutions. A new operating reserve strategy, referred to as flexibility reserve, has been introduced in some regions. A similar implementation is explored in this paper, and its implications on power system operations are analyzed.

  3. Evaluation and improvement in nondestructive examination (NDE) reliability for inservice inspection of light water reactors

    International Nuclear Information System (INIS)

    Doctor, S.R.; Deffenbaugh, J.D.; Good, M.S.; Green, E.R.; Heasler, P.G.; Simonen, F.A.; Spanner, J.C.; Taylor, T.T.

    1988-01-01

    The Evaluation and Improvement of NDE Reliability for Inservice Inspection of Light Water Reactor (NDE Reliability) program at the Pacific Northwest Laboratory was established by the NRC to determine the reliability of current inservice inspection (ISI) techniques and to develop recommendations that will ensure a suitably high inspection reliability. The objectives of this program include determining the reliability of ISI performed on the primary systems of commercial light-water reactors (LWRs); using probabilistic fracture mechanics analysis to determine the impact of NDE unreliability on system safety; and evaluating reliability improvements that can be achieved with improved and advanced technology. A final objective is to formulate recommended revisions to ASME Code and Regulatory requirements, based on material properties, service conditions, and NDE uncertainties. The program scope is limited to ISI of the primary systems including the piping, vessel, and other inspected components. This is a progress report covering the programmatic work from October 1986 through September 1987

  4. Evaluation and improvement in nondestructive examination (NDE) reliability for inservice inspection of light water reactors

    International Nuclear Information System (INIS)

    Doctor, S.R.; Deffenbaugh, J.D.; Good, M.S.; Green, E.R.; Heasler, P.G.; Simonen, F.A.; Spanner, J.C.; Taylor, T.T.

    1988-01-01

    The Evaluation and Improvement of NDE Reliability for Inservice Inspection of Light Water Reactors (NDE Reliability) program at the Pacific Northwest Laboratory was established by the NRC to determine the reliability of current inservice inspection (ISI) techniques and to develop recommendations that will ensure a suitably high inspection reliability. The objectives of this program include determining the reliability of ISI performed on the primary systems of commercial light-water reactors (LWRs); using probabilistic fracture mechanics analysis to determine the impact of NDE unreliability on system safety; and evaluating reliability improvements that can be achieved with improved and advanced technology. A final objective is to formulate recommended revisions to ASME Code and Regulatory requirements, based on material properties, service conditions and NDE uncertainties. The program scope is limited to ISI of the primary systems including the piping, vessel, and other inspected components. This is a progress report covering the programmatic work from October 1986 through September 1987. (author)

  5. Control Strategies for Improving Energy Efficiency and Reliability in Autonomous Microgrids with Communication Constraints

    Directory of Open Access Journals (Sweden)

    Francisco Martins Portelinha Júnior

    2017-09-01

    Full Text Available Microgrids are a feasible path to deploy smart grids, an intelligent and highly automated power system. Their operation demands a dedicated communication infrastructure to manage, control and monitor the intermittent sources of energy and loads. Therefore, smart devices will be connected to support the growth of grid smartness increasing the dependency on communication networks, which consumes a high amount of power. In an energy-limited scenario, one of the main issues is to enhance the power supply time. Therefore, this paper proposes a hybrid methodology for microgrid energy management, integrated with a communication infrastructure to improve and to optimize islanded microgrid operation at maximum energy efficiency. The hybrid methodology applies some control management rules, such as intentional load shedding, priority load management, and communication energy saving. These energy saving rules establish a trade-off between increasing microgrid energy availability and communication system reliability. To achieve a compromised solution, a continuous time Markov chain model describes the impact of energy saving policies into system reliability. The proposed methodology is simulated and tested with the help of the modified IEEE 34 node test-system.

  6. Improving Reliability of Embedded Systems through Dynamic Memory Manager Optimization using Grammatical Evolution

    OpenAIRE

    Colmenar, J. Manuel; Risco-Martin, Jose L.; Atienza Alonso, David; Garnica, Oscar; Hidalgo, Jose I.; Lanchares, Juan

    2010-01-01

    Technology scaling has offered advantages to embedded systems, such as increased performance, more available memory and reduced energy consumption. However, scaling also brings a number of problems like reliability degradation mechanisms. The intensive activity of devices and high operating temperatures are key factors for reliability degradation in latest technology nodes. Focusing on embedded systems, the memory is prone to suffer reliability problems due to the intensive use of dynamic mem...

  7. TESTING METHODS FOR MECHANICALLY IMPROVED SOILS: RELIABILITY AND VALIDITY

    Directory of Open Access Journals (Sweden)

    Ana Petkovšek

    2017-10-01

    Full Text Available A possibility of in-situ mechanical improvement for reducing the liquefaction potential of silty sands was investigated by using three different techniques: Vibratory Roller Compaction, Rapid Impact Compaction (RIC and Soil Mixing. Material properties at all test sites were investigated before and after improvement with the laboratory and the in situ tests (CPT, SDMT, DPSH B, static and dynamic load plate test, geohydraulic tests. Correlation between the results obtained by different test methods gave inconclusive answers.

  8. The experiences to improve plant performance and reliability of Ko-Ri nuclear power plants

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Ho Weon [Korea Electric Power Corp. Ko-Ri nuclear power division, Ko-Ri (Korea, Republic of)

    1998-07-01

    This paper provides a discussion of the lessons learned from operational experience and the future plans to improve performance of the Ko-Ri plant. To operate nuclear power plants safely with good performance is the only way to mitigate the negative image of nuclear power generation to the public and to enhance the economical benefit compared to other electrical generation method. Therefore, in a continuous effort to overcome a negative challenge from outside, we have driven an aggressive 'OCTF' campaign as part of safety. As a result of our efforts, the following remarkable achievements have been accomplished. (1) 3 times of OCTF during recent three years (2) Selected twice as a top notch power plant on the list of NEI magazine in terms of plant capacity factor (3) No scram recorded in 1997 for all 4 units at Ko-Ri site. Ko-Ri is now undergoing the large scale plant betterment projects for retaking-off our operating performance to the level of new challenge target. Such improvement of critical components in the reactor coolant system and turbine system greatly contribute to increase the safety and reliability of the plant and to shortening of the planned outage period as well as to reduction of radiation exposure and radwaste. (Cho, G. S.). 5 tabs., 10 figs.

  9. The experiences to improve plant performance and reliability of Ko-Ri nuclear power plants

    International Nuclear Information System (INIS)

    Kang, Ho Weon

    1998-01-01

    This paper provides a discussion of the lessons learned from operational experience and the future plans to improve performance of the Ko-Ri plant. To operate nuclear power plants safely with good performance is the only way to mitigate the negative image of nuclear power generation to the public and to enhance the economical benefit compared to other electrical generation method. Therefore, in a continuous effort to overcome a negative challenge from outside, we have driven an aggressive 'OCTF' campaign as part of safety. As a result of our efforts, the following remarkable achievements have been accomplished. (1) 3 times of OCTF during recent three years (2) Selected twice as a top notch power plant on the list of NEI magazine in terms of plant capacity factor (3) No scram recorded in 1997 for all 4 units at Ko-Ri site. Ko-Ri is now undergoing the large scale plant betterment projects for retaking-off our operating performance to the level of new challenge target. Such improvement of critical components in the reactor coolant system and turbine system greatly contribute to increase the safety and reliability of the plant and to shortening of the planned outage period as well as to reduction of radiation exposure and radwaste. (Cho, G. S.). 5 tabs., 10 figs

  10. New application of dynamic reliability assessment of the mid-loop operation

    International Nuclear Information System (INIS)

    Moosung, Jae; Goon Cherl Park; Chang Hyun Chung

    1995-01-01

    This paper presents a new approach for assessing the dynamic reliability in a complex system such as a nuclear power plant. The method is applied to a dynamic analysis of the potential accident sequences that may occur during mid-loop operation

  11. Power system reliability impacts of wind generation and operational reserve requirements

    Directory of Open Access Journals (Sweden)

    Esteban Gil

    2015-06-01

    Full Text Available Due to its variability, wind generation integration presents a significant challenge to power system operators in order to maintain adequate reliability levels while ensuring least cost operation. This paper explores the trade-off between the benefits associated to a higher wind penetration and the additional operational reserve requirements that they impose. Such exploration is valued in terms of its effect on power system reliability, measured as an amount of unserved energy. The paper also focuses on how changing the Value of Lost Load (VoLL can be used to attain different reliability targets, and how wind power penetration and the diversity of the wind energy resource will impact quality of supply (in terms of instances of unserved energy. The evaluation of different penetrations of wind power generation, different wind speed profiles, wind resource diversity, and different operational reserve requirements, is conducted on the Chilean Northern Interconnected System (SING using statistical modeling of wind speed time series and computer simulation through a 24-hour ahead unit commitment algorithm and a Monte Carlo simulation scheme. Results for the SING suggest that while wind generation can significantly reduce generation costs, it can also imply higher security costs to reach acceptable reliability levels.

  12. Reliability analysis and risk-based methods for planning of operation & maintenance of offshore wind turbines

    DEFF Research Database (Denmark)

    Sørensen, John Dalsgaard

    2017-01-01

    for extreme and fatigue limit states are presented. Operation & Maintenance planning often follows corrective and preventive strategies based on information from condition monitoring and structural health monitoring systems. A reliability- and risk-based approach is presented where a life-cycle approach...

  13. Lamp reliability studies for improved satellite rubidium frequency standard

    Science.gov (United States)

    Frueholz, R. P.; Wun-Fogle, M.; Eckert, H. U.; Volk, C. H.; Jones, P. F.

    1982-01-01

    In response to the premature failure of Rb lamps used in Rb atomic clocks onboard NAVSTAR GPS satellites experimental and theoretical investigations into their failure mechanism were initiated. The primary goal of these studies is the development of an accelerated life test for future GPS lamps. The primary failure mechanism was identified as consumption of the lamp's Rb charge via direct interaction between Rb and the lamp's glass surface. The most effective parameters to accelerate the interaction between the Rb and the glass are felt to be RF excitation power and lamp temperature. Differential scanning calorimetry is used to monitor the consumption of Rb within a lamp as a function of operation time. This technique yielded base line Rb consumption data for GPS lamps operating under normal conditions.

  14. Improving the Reliability of Tinnitus Screening in Laboratory Animals.

    Science.gov (United States)

    Jones, Aikeen; May, Bradford J

    2017-02-01

    Behavioral screening remains a contentious issue for animal studies of tinnitus. Most paradigms base a positive tinnitus test on an animal's natural tendency to respond to the "sound" of tinnitus as if it were an actual sound. As a result, animals with tinnitus are expected to display sound-conditioned behaviors when no sound is present or to miss gaps in background sounds because tinnitus "fills in the gap." Reliable confirmation of the behavioral indications of tinnitus can be problematic because the reinforcement contingencies of conventional discrimination tasks break down an animal's tendency to group tinnitus with sound. When responses in silence are rewarded, animals respond in silence regardless of their tinnitus status. When responses in silence are punished, animals stop responding. This study introduces stimulus classification as an alternative approach to tinnitus screening. Classification procedures train animals to respond to the common perceptual features that define a group of sounds (e.g., high pitch or narrow bandwidth). Our procedure trains animals to drink when they hear tinnitus and to suppress drinking when they hear other sounds. Animals with tinnitus are revealed by their tendency to drink in the presence of unreinforced probe sounds that share the perceptual features of the tinnitus classification. The advantages of this approach are illustrated by taking laboratory rats through a testing sequence that includes classification training, the experimental induction of tinnitus, and postinduction screening. Behavioral indications of tinnitus are interpreted and then verified by simulating a known tinnitus percept with objective sounds.

  15. Advanced surface protection for improved reliability PCB systems (ASPIS)

    NARCIS (Netherlands)

    Ballantyne, A.; Forrest, G.; Goosey, M.; Griguceviciene, A.; Juodkazyte, J.; Kellner, R.; Kosenko, A.; Ramanauskas, R.; Ryder, K.; Selskis, A.; Tarozaite, R.; Veninga, E.

    2012-01-01

    Purpose - The purpose of this paper is to detail progress on the European Commission supported FP7 ASPIS project that is undertaking a multi-faceted approach to develop novel and improved nickel-gold (ENIG) solderable finish chemistries and processes in order to overcome issues such as "black pad"

  16. Recent operating experience and improvement of commercial IGCC

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2013-09-01

    IGCC has today reached a status where experience is available from first and second generation plants, built in the 1970s/1980s and in the 1990s respectively, as commercial-scale demonstration plants for coal-based applications. These plants feature variations on gasification technology and subsequent environmental controls and in operating them a number of technical and commercial lessons have been learned that will help to improve the next generation of IGCC projects. The report reviews and summarises the state-of-the-art and operating experience of several commercial IGCC plants worldwide, setting out the lessons learned and plans for future development embracing such issues as the changes or modifications to plant made to overcome the operational problems and to improve the reliability and availability of the plant. Since IGCC is considered a 'capture ready' technology for CO2 abatement, the current status with regard to the incorporation of carbon capture and storage systems (CCS) has been reviewed. Finally, the report outlines the issues associated with assessing the risks in commercialising IGCC plant.

  17. Operation reliability analysis of independent power plants of gas-transmission system distant production facilities

    Science.gov (United States)

    Piskunov, Maksim V.; Voytkov, Ivan S.; Vysokomornaya, Olga V.; Vysokomorny, Vladimir S.

    2015-01-01

    The new approach was developed to analyze the failure causes in operation of linear facilities independent power supply sources (mini-CHP-plants) of gas-transmission system in Eastern part of Russia. Triggering conditions of ceiling operation substance temperature at condenser output were determined with mathematical simulation use of unsteady heat and mass transfer processes in condenser of mini-CHP-plants. Under these conditions the failure probability in operation of independent power supply sources is increased. Influence of environmental factors (in particular, ambient temperature) as well as output electric capability values of power plant on mini-CHP-plant operation reliability was analyzed. Values of mean time to failure and power plant failure density during operation in different regions of Eastern Siberia and Far East of Russia were received with use of numerical simulation results of heat and mass transfer processes at operation substance condensation.

  18. Practical applications of age-dependent reliability models and analysis of operational data

    Energy Technology Data Exchange (ETDEWEB)

    Lannoy, A.; Nitoi, M.; Backstrom, O.; Burgazzi, L.; Couallier, V.; Nikulin, M.; Derode, A.; Rodionov, A.; Atwood, C.; Fradet, F.; Antonov, A.; Berezhnoy, A.; Choi, S.Y.; Starr, F.; Dawson, J.; Palmen, H.; Clerjaud, L

    2005-07-01

    The purpose of the workshop was to present the experience of practical application of time-dependent reliability models. The program of the workshop comprises the following sessions: -) aging management and aging PSA (Probabilistic Safety Assessment), -) modeling, -) operation experience, and -) accelerating aging tests. In order to introduce time aging effect of particular component to the PSA model, it has been proposed to use the constant unavailability values on the short period of time (one year for example) calculated on the basis of age-dependent reliability models. As for modeling, it appears that the problem of too detailed statistical models for application is the lack of data for required parameters. As for operating experience, several methods of operating experience analysis have been presented (algorithms for reliability data elaboration and statistical identification of aging trend). As for accelerated aging tests, it is demonstrated that a combination of operating experience analysis with the results of accelerated aging tests of naturally aged equipment could provide a good basis for continuous operation of instrumentation and control systems.

  19. Practical applications of age-dependent reliability models and analysis of operational data

    International Nuclear Information System (INIS)

    Lannoy, A.; Nitoi, M.; Backstrom, O.; Burgazzi, L.; Couallier, V.; Nikulin, M.; Derode, A.; Rodionov, A.; Atwood, C.; Fradet, F.; Antonov, A.; Berezhnoy, A.; Choi, S.Y.; Starr, F.; Dawson, J.; Palmen, H.; Clerjaud, L.

    2005-01-01

    The purpose of the workshop was to present the experience of practical application of time-dependent reliability models. The program of the workshop comprises the following sessions: -) aging management and aging PSA (Probabilistic Safety Assessment), -) modeling, -) operation experience, and -) accelerating aging tests. In order to introduce time aging effect of particular component to the PSA model, it has been proposed to use the constant unavailability values on the short period of time (one year for example) calculated on the basis of age-dependent reliability models. As for modeling, it appears that the problem of too detailed statistical models for application is the lack of data for required parameters. As for operating experience, several methods of operating experience analysis have been presented (algorithms for reliability data elaboration and statistical identification of aging trend). As for accelerated aging tests, it is demonstrated that a combination of operating experience analysis with the results of accelerated aging tests of naturally aged equipment could provide a good basis for continuous operation of instrumentation and control systems

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

    Science.gov (United States)

    Shafiee-Jood, M.; Cai, X.

    2017-12-01

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

  1. Efforts to improve safety and reliability of nuclear power plants in Kyushu Electric Power

    International Nuclear Information System (INIS)

    Yamamoto, Satoshi

    2014-01-01

    After the Fukushima accident, Kyushu Electric Power Co. took emergency safety measures requested by government to ensure power supply, coolant supply pumps and cooling water so as to keep cooling fuels in the reactor and spent fuel storage pool in case of losses of ordinary cooling capability caused by earthquake and tsunami. In order to improve safety and reliability of nuclear power plants, further efforts based on lessons learned from the Fukushima accident had been made to diversify corresponding equipment of safety measures in terms of prevention of core damage, prevention of containment failure, mitigation of radioactive materials release, cooling of spent fuel pit and ensurance of power supply, and to enhance emergency response capability so as to make operational management more complete. Additional safety measures applicable to new regulatory requirements against severe accidents were in progress. This article introduced details of such activities. (T. Tanaka)

  2. Data collection on the unit control room simulator as a method of operator reliability analysis

    International Nuclear Information System (INIS)

    Holy, J.

    1998-01-01

    The report consists of the following chapters: (1) Probabilistic assessment of nuclear power plant operation safety and human factor reliability analysis; (2) Simulators and simulations as human reliability analysis tools; (3) DOE project for using the collection and analysis of data from the unit control room simulator in human factor reliability analysis at the Paks nuclear power plant; (4) General requirements for the organization of the simulator data collection project; (5) Full-scale simulator at the Nuclear Power Plants Research Institute in Trnava, Slovakia, used as a training means for operators of the Dukovany NPP; (6) Assessment of the feasibility of quantification of important human actions modelled within a PSA study by employing simulator data analysis; (7) Assessment of the feasibility of using the various exercise topics for the quantification of the PSA model; (8) Assessment of the feasibility of employing the simulator in the analysis of the individual factors affecting the operator's activity; and (9) Examples of application of statistical methods in the analysis of the human reliability factor. (P.A.)

  3. Forecasting Wind and Solar Generation: Improving System Operations, Greening the Grid (Spanish Version)

    Energy Technology Data Exchange (ETDEWEB)

    Tian, Tian; Chernyakhovskiy, Ilya; Brancucci Martinez-Anido, Carlo

    2016-04-01

    This document is the Spanish version of 'Greening the Grid- Forecasting Wind and Solar Generation Improving System Operations'. It discusses improving system operations with forecasting with and solar generation. By integrating variable renewable energy (VRE) forecasts into system operations, power system operators can anticipate up- and down-ramps in VRE generation in order to cost-effectively balance load and generation in intra-day and day-ahead scheduling. This leads to reduced fuel costs, improved system reliability, and maximum use of renewable resources.

  4. Validity and reliability of a dental operator posture assessment instrument (PAI).

    Science.gov (United States)

    Branson, Bonnie G; Williams, Karen B; Bray, Kimberly Krust; Mcllnay, Sandy L; Dickey, Diana

    2002-01-01

    Basic operating posture is considered an important occupational health issue for oral health care clinicians. It is generally agreed that the physical posture of the operator, while providing care, should be such that all muscles are in a relaxed, well-balanced, and neutral position. Postures outside of this neutral position are likely to cause musculoskeletal discomfort. To date, the range of the neutral operator position has not been well-defined; nor have any specific instruments been identified that can quantitatively or semi-quantitatively assess dental operator posture. This paper reports on the development of an instrument that can be used to semi-quantitatively evaluate postural components. During the first phase of the study, an expert panel defined the basic parameters for acceptable, compromised, and harmful operator postures and established face validity of a posture assessment instrument (PAI). During the second phase, the PAI was tested for reliability using generalizability theory. Four raters tested the instrument for reliability. Overall, total PAI scores were similar amongst three of the raters, with the fourth rater's scores being slightly greater than the other three. The main effect of the rater on individual postural components was moderate, indicating that rater variance contributed to 11.9% of total variance. The PAI measures posture as it occurs and will have numerous applications when evaluating operator performance in the dental and dental hygiene education setting. Also, the PAI will prove useful when examining the effects of operator posture and musculoskeletal disorders.

  5. Reliability improvement: where do we go from here. The role of codes and standards

    International Nuclear Information System (INIS)

    Davidson, R.H.

    1976-01-01

    The role of codes and standards in contributing to the future improvement is discussed. The Nuclear Plant Reliability Data System is examined. It is suggested that two systems of the type are needed. One system should focus on component and system reliability while the other should focus on system availability, capacity factor, and fixed outage rate assessment

  6. Training Improves Interobserver Reliability for the Diagnosis of Scaphoid Fracture Displacement

    NARCIS (Netherlands)

    Buijze, Geert A.; Guitton, Thierry G.; van Dijk, C. Niek; Ring, David; Osterman, A. Lee; Wahegaonkar, Abhijeet L.; Ladd, Amy; Barquet, Antonio; van Vugt, Arie B.; Shyam, Ashok K.; Swigart, Carrie; Coles, Chad P.; Zalavras, Charalampos; Goldfarb, Charles A.; Cassidy, Charles; Allan, Christopher; Beingessner, Daphne; Kalainov, David M.; Eygendaal, Denise; Sancheti, Parag; Feibel, Robert J.; Rocha, Steve; Grosso, Elena; Frihagen, Frede; Dyer, George S. M.; Athwal, George S.; Goslings, J. Carel; Della Rocca, Gregory J.; Harris, Ian; Fanuele, Jason C.; Lawton, Jeff; Jiuliano, John; McAuliffe, John; Capo, John T.; Conflitti, Joseph M.; Segalman, Keith; Egol, Kenneth; Ponsen, Kornelis J.; Jeray, Kyle; Lattanza, Lisa; Catalano, Louis; Swiontkowski, Marc; Boyer, Martin; Richardson, Martin; Soong, Maximillian; Baskies, Michael; Prayson, Michael; McKee, Michael; Chen, Neal C.; Kloen, Peter

    2012-01-01

    The diagnosis of displacement in scaphoid fractures is notorious for poor interobserver reliability. We tested whether training can improve interobserver reliability and sensitivity, specificity, and accuracy for the diagnosis of scaphoid fracture displacement on radiographs and CT scans. Sixty-four

  7. Increase of operational reliability and durability of square sectoral working bodies of flexible screw conveyors

    Directory of Open Access Journals (Sweden)

    O.L. Lyashuk

    2017-12-01

    Full Text Available The construction of the device for guiding screw sectional working bodies of increased operational reliability and durability and the method of determination of the force of guiding the design parameters are given. Two main methods of manufacturing screw mechanisms of machines of various service purposes were investigated and it was established that twisted screws, in terms of their strength and performance, considerably exceed rolling stock. The design of the device for manufacturing screw working bodies of conveyors by means of cutting by periodic and continuous methods, as the most reliable in operation, is developed. The specifics of their work are due to various operations of technological processes, as well as physical and mechanical properties of goods, determine the nomenclature and design parameters of screw mechanisms (SM. In studying the processes of forming screw spirals, the basic precision characteristics of the methods of drilling and rolling are established. A comparative study of two main methods in terms of their operational and durable capabilities has been carried out. An important factor determining the reliability and durability of a screw is the difference in the thickness of the inner and outer edges.

  8. Improving QST Reliability – More Raters, Tests or Occasions? A Multivariate Generalizability Study

    DEFF Research Database (Denmark)

    O'Neill, Søren; O'Neill, Lotte

    2015-01-01

    The reliability of quantitative sensory testing (QST) is affected by the error attributable to both test occasion and rater (examiner) as well as interactions between them. Most reliability studies only account for one source of error. The present study employed a fully-crossed, multivariate...... threshold, intensity, tolerance and modulation with mechanical, thermal and chemical stimuli. The classical test-retest and inter-rater reliability (0.19... procedures. Reliability was improved more by repeated testing on separate occasions opposed to repeated testing by different raters....

  9. Reliability Calculations

    DEFF Research Database (Denmark)

    Petersen, Kurt Erling

    1986-01-01

    Risk and reliability analysis is increasingly being used in evaluations of plant safety and plant reliability. The analysis can be performed either during the design process or during the operation time, with the purpose to improve the safety or the reliability. Due to plant complexity and safety...... and availability requirements, sophisticated tools, which are flexible and efficient, are needed. Such tools have been developed in the last 20 years and they have to be continuously refined to meet the growing requirements. Two different areas of application were analysed. In structural reliability probabilistic...... approaches have been introduced in some cases for the calculation of the reliability of structures or components. A new computer program has been developed based upon numerical integration in several variables. In systems reliability Monte Carlo simulation programs are used especially in analysis of very...

  10. Model improves oil field operating cost estimates

    International Nuclear Information System (INIS)

    Glaeser, J.L.

    1996-01-01

    A detailed operating cost model that forecasts operating cost profiles toward the end of a field's life should be constructed for testing depletion strategies and plans for major oil fields. Developing a good understanding of future operating cost trends is important. Incorrectly forecasting the trend can result in bad decision making regarding investments and reservoir operating strategies. Recent projects show that significant operating expense reductions can be made in the latter stages o field depletion without significantly reducing the expected ultimate recoverable reserves. Predicting future operating cost trends is especially important for operators who are currently producing a field and must forecast the economic limit of the property. For reasons presented in this article, it is usually not correct to either assume that operating expense stays fixed in dollar terms throughout the lifetime of a field, nor is it correct to assume that operating costs stay fixed on a dollar per barrel basis

  11. Improved Yield, Performance and Reliability of High-Actuator-Count Deformable Mirrors, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — The project team will conduct processing and design research aimed at improving yield, performance, and reliability of high-actuator-count micro-electro-mechanical...

  12. Reliability Improvement of Power Converters by Means of Condition Monitoring of IGBT Modules

    DEFF Research Database (Denmark)

    Choi, Ui Min; Blaabjerg, Frede; Jørgensen, S.

    2017-01-01

    Power electronic systems have gradually gained an important status in a wide range of industrial applications such as renewable generation, motor drives, automotive, and railway transportation. Accordingly, recent research makes an effort to improve the reliability of power electronic systems...

  13. Efficiency improvement of nuclear power plant operation: the significant role of advanced nuclear fuel technologies

    International Nuclear Information System (INIS)

    Van Velde, AA. de; Burtak, F.

    2000-01-01

    In this paper authors deals with nuclear fuel cycle and their economic aspects. At Siemens, the developments focusing on the reduction of fuel cycle costs are currently directed on .further batch average burnup increase, .improvement of fuel reliability, .enlargement of fuel operation margins, .improvement of methods for fuel design and core analysis. These items will be presented in detail in the full paper and illustrated by the global operating experience of Siemens fuel for both PWRs and BWRs. (authors)

  14. Improving operating room coordination: communication pattern assessment.

    Science.gov (United States)

    Moss, Jacqueline; Xiao, Yan

    2004-02-01

    To capture communication patterns in operating room (OR) management to characterize the information needs of OR coordination. Technological applications can be used to change system processes to improve communication and information access, thereby decreasing errors and adverse events. The successful design of such applications relies on an understanding of communication patterns among healthcare professionals. Charge nurse communication was observed and documented at four OR suites at three tertiary hospitals. The data collection tool allowed rapid coding of communication patterns in terms of duration, mode, target person, and the purpose of each communication episode. Most (69.24%) of the 2074 communication episodes observed occurred face to face. Coordinating equipment was the most frequently occurring purpose of communication (38.7%) in all suites. The frequency of other purposes in decreasing order were coordinating patient preparedness (25.7%), staffing (18.8%), room assignment (10.7%), and scheduling and rescheduling surgery (6.2%). The results of this study suggest that automating aspects of preparing patients for surgery and surgical equipment management has the potential to reduce information exchange, decreasing interruptions to clinicians and diminishing the possibility of adverse events in the clinical setting.

  15. Wind turbine reliability :understanding and minimizing wind turbine operation and maintenance costs.

    Energy Technology Data Exchange (ETDEWEB)

    Walford, Christopher A. (Global Energy Concepts. Kirkland, WA)

    2006-03-01

    Wind turbine system reliability is a critical factor in the success of a wind energy project. Poor reliability directly affects both the project's revenue stream through increased operation and maintenance (O&M) costs and reduced availability to generate power due to turbine downtime. Indirectly, the acceptance of wind-generated power by the financial and developer communities as a viable enterprise is influenced by the risk associated with the capital equipment reliability; increased risk, or at least the perception of increased risk, is generally accompanied by increased financing fees or interest rates. This paper outlines the issues relevant to wind turbine reliability for wind turbine power generation projects. The first sections describe the current state of the industry, identify the cost elements associated with wind farm O&M and availability and discuss the causes of uncertainty in estimating wind turbine component reliability. The latter sections discuss the means for reducing O&M costs and propose O&M related research and development efforts that could be pursued by the wind energy research community to reduce cost of energy.

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

    International Nuclear Information System (INIS)

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

    1988-06-01

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

  17. Intra-operative reliability of ShapeMatch cutting guide placement in total knee arthroplasty.

    Science.gov (United States)

    Clark, Gavin; Leong, Anthony; McEwen, Peter; Steele, Robert; Tran, Ton; Trivett, Adrian

    2013-01-01

    Custom cutting guides based on pre-operative imaging have been introduced for total knee arthroplasty (TKA). The aim of this prospective cohort study was to assess the reliability of repeated placement of custom cutting guides by multiple surgeons in a group of patients undergoing TKA. Custom cutting guides (ShapeMatch®, Stryker Orthopaedics) were designed from pre-operative MRI scans. The treating surgeon placed each guide on the femur and tibia of each patient three times without pinning the block. The three-dimensional position and orientation of the guide was measured for each repetition using a computer navigation system. The surgeon was blinded to the navigation system display. Data from 24 patients and 6 surgeons were analyzed. Intraclass correlation coefficients for all measurement parameters were in the range 0.889-0.997 (excellent), and all comparisons were statistically significant (p reliable.

  18. Reliability Evaluation and Improvement Approach of Chemical Production Man - Machine - Environment System

    Science.gov (United States)

    Miao, Yongchun; Kang, Rongxue; Chen, Xuefeng

    2017-12-01

    In recent years, with the gradual extension of reliability research, the study of production system reliability has become the hot topic in various industries. Man-machine-environment system is a complex system composed of human factors, machinery equipment and environment. The reliability of individual factor must be analyzed in order to gradually transit to the research of three-factor reliability. Meanwhile, the dynamic relationship among man-machine-environment should be considered to establish an effective blurry evaluation mechanism to truly and effectively analyze the reliability of such systems. In this paper, based on the system engineering, fuzzy theory, reliability theory, human error, environmental impact and machinery equipment failure theory, the reliabilities of human factor, machinery equipment and environment of some chemical production system were studied by the method of fuzzy evaluation. At last, the reliability of man-machine-environment system was calculated to obtain the weighted result, which indicated that the reliability value of this chemical production system was 86.29. Through the given evaluation domain it can be seen that the reliability of man-machine-environment integrated system is in a good status, and the effective measures for further improvement were proposed according to the fuzzy calculation results.

  19. The Reliability of In-Training Assessment when Performance Improvement Is Taken into Account

    Science.gov (United States)

    van Lohuizen, Mirjam T.; Kuks, Jan B. M.; van Hell, Elisabeth A.; Raat, A. N.; Stewart, Roy E.; Cohen-Schotanus, Janke

    2010-01-01

    During in-training assessment students are frequently assessed over a longer period of time and therefore it can be expected that their performance will improve. We studied whether there really is a measurable performance improvement when students are assessed over an extended period of time and how this improvement affects the reliability of the…

  20. An Improved Distortion Operator for Insurance Risks

    Institute of Scientific and Technical Information of China (English)

    GAO Jian-wei; QIU Wan-hua

    2002-01-01

    This paper reviews the distortion function approach developed in the actuarial literature for insurance risks. The main aim of this paper is to derive an extensive distortion operator, and to propose a new premium principle based on this extensive distortion operator. Furthermore, the non-robustness of general distortion operator is also discussed. Examples are provided using Bernoulli, Pareto, Lognormal and Gamma distribution assumptions.

  1. Studies on the reliability of high-field intra-operative MRI in brain glioma resection

    Directory of Open Access Journals (Sweden)

    Zhi-jun SONG

    2011-07-01

    Full Text Available Objective To evaluate the reliability of high-field intra-operative magnetic resonance imaging(iMRI in detecting the residual tumors during glioma resection.Method One hundred and thirty-one cases of brain glioma(69 males and 62 females,aged from 7 to 79 years with mean of 39.6 years hospitalized from Nov.2009 to Aug.2010 were involved in present study.All the patients were evaluated using magnetic resonance imaging(MRI before the operation.The tumors were resected under conventional navigation microscope,and the high-field iMRI was used for all the patients when the operators considered the tumor was satisfactorily resected,while the residual tumor was difficult to detect under the microscope,but resected after being revealed by high-field iMRI.Histopathological examination was performed.The patients without residual tumors recieved high-field MRI scan at day 4 or 5 after operation to evaluate the accuracy of high-field iMRI during operation.Results High quality intra-operative images were obtained by using high-field iMRI.Twenty-eight cases were excluded because their residual tumors were not resected due to their location too close to functional area.Combined with the results of intra-operative histopathological examination and post-operative MRI at the early recovery stage,the sensitivity of high-field iMRI in residual tumor diagnosis was 98.0%(49/50,the specificity was 94.3%(50/53,and the accuracy was 96.1%(99/103.Conclusion High-quality intra-operative imaging could be acquired by high-field iMRI,which maybe used as a safe and reliable method in detecting the residual tumors during glioma resection.

  2. Design basis programs and improvements in plant operation

    International Nuclear Information System (INIS)

    Metcalf, M.F.

    1991-01-01

    Public Service Electric and Gas (PSE and G) Company operates three commercial nuclear power plants in southern New Jersey. The three plants are of different designs and vintages (two pressurized water reactors licensed in 1976 and 1980 and one boiling water reactor licensed in 1986). As the industry recognized the need to develop design basis programs, PSE and G also realized the need after a voluntary 52-day shutdown of one unit because of electrical design basis problems. In its drive to be a premier electric utility, PSE and G has been aggressively active in developing design basis documents (DBDs) with supporting projects and refined uses to obtain the expected value and see the return on investment. Progress on Salem is nearly 75% complete, while Hope Creek is 20% complete. To data, PSE and G has experienced success in the use of DBDs in areas such as development of plant modifications, development of the reliability-centered maintenance program, procedure upgrades, improved document retrieval, resolution of regulatory issues, and training. The paper examines the design basis development process, supporting projects, and expected improvements in plant operations as a result of these efforts

  3. Use of a valve operation test and evaluation system to enhance valve reliability

    International Nuclear Information System (INIS)

    Lowry, D.A.

    1990-01-01

    Power plant owners have emphasized the need for assuring safe, reliable operation of valves. While most valves must simply open or close, the mechanisms involved can be quite complex. Motor operated valves (MOVs) must be properly adjusted to assure operability. Individual operator components determine the performance of the entire MOV. Failure in MOVs could cripple or shut down a unit. Thus, a complete valve program consisting of design reviews, operational testing, and preventive and predictive maintenance activities will enhance an owner's confidence level that his valves win operate as expected. Liberty's Valve Operation Test and Evaluation System (VOTES) accurately measures stein thrust without intruding on valve operation. Since mounting a strain gage to a valve stem is a desirable but impractical way of obtaining precise stem thrust, Liberty developed a method to obtain identical data by placing a strain gage sensor on the valve yoke. VOTES provides information which effectively eliminates costly, unscheduled downtime. This paper presents the results of infield VOTES testing. The system's proven ability to identify and characterize actuator and valve performance is demonstrated. Specific topics of discussion include the ability of VOTES to ease a utility's IE Bulletin 8543 concerns and conclusively diagnose MOV components. Data from static and differential pressure testing are presented. Technical, operational, and financial advantages resulting from VOTES technology are explored in detail

  4. Operating reliability of valves in French pressurized water nuclear power plants

    International Nuclear Information System (INIS)

    Conte

    1986-10-01

    Taking into account the large numbers of valves (about 10000) of a PWR nuclear power plant, the importance of some valves in the safety functions and the cost resulting from their unavailability, the individual operability of these equipments has to be ensured at a high reliability level. This assurance can be obtained by means of an effort at all the stages which contribute to the quality of the product: design, qualification tests, fabrication, tests at the start-up stage, maintenance and tests during the power plant operation, experience feedback. This paper emphasizes more particularly on the tests carried out on loops of qualification [fr

  5. Application of Bayesian Belief networks to the human reliability analysis of an oil tanker operation focusing on collision accidents

    International Nuclear Information System (INIS)

    Martins, Marcelo Ramos; Maturana, Marcos Coelho

    2013-01-01

    During the last three decades, several techniques have been developed for the quantitative study of human reliability. In the 1980s, techniques were developed to model systems by means of binary trees, which did not allow for the representation of the context in which human actions occur. Thus, these techniques cannot model the representation of individuals, their interrelationships, and the dynamics of a system. These issues make the improvement of methods for Human Reliability Analysis (HRA) a pressing need. To eliminate or at least attenuate these limitations, some authors have proposed modeling systems using Bayesian Belief Networks (BBNs). The application of these tools is expected to address many of the deficiencies in current approaches to modeling human actions with binary trees. This paper presents a methodology based on BBN for analyzing human reliability and applies this method to the operation of an oil tanker, focusing on the risk of collision accidents. The obtained model was used to determine the most likely sequence of hazardous events and thus isolate critical activities in the operation of the ship to study Internal Factors (IFs), Skills, and Management and Organizational Factors (MOFs) that should receive more attention for risk reduction.

  6. How to keep your steam generator working with low costs for a long and reliable operating time

    International Nuclear Information System (INIS)

    Flammann, T.

    1998-01-01

    Strategic planning of steam generator (SG) maintenance and repair is a key issue for plant availability and reliability. In Germany, maintenance and eventual repair considerations are an integrated part of a multistep concept for reliable SG performance. This concept is addressed as early as in the design phase of a nuclear power plant. In contrast to the tube degradation problems that have been encountered worldwide, SGs of the Siemens/KWU design have proven by operating experience that they are very efficient in minimizing tube corrosion or any other SG related problems. A multilevel concept has been developed, applied and wherever necessary improved in order to ensure reliable operation. The main elements of this concept are thorough design engineering incl. proper material selection and stringent requirements and quality control for fabrication accompanied by tight control requirements of water chemistry environments. In order to counteract tube deficiencies a complete arsenal of maintenance, inspection- and repair-techniques have been developed and successfully applied. Performance of SG is continuously evaluated and fixed in lifetime databases. The main indicator for SG integrity still is the eddy-current testing of SG tubes. SG tubes which have shown indications at the eddy current tests are rated with lifetime threshold values and SGs affected by tube damages are inspected, and eventually, repaired, based on individual assessment criteria. (author)

  7. Process control upgrades yield huge operational improvements

    International Nuclear Information System (INIS)

    Fitzgerald, W.V.

    2001-01-01

    Most nuclear plants in North America were designed and built in the late 60 and 70. The regulatory nature of this industry over the years has made design changes at the plant level difficult, if not impossible, to implement. As a result, many plants in this world region have been getting by on technology that is over 40 years behind the times. What this translates into is that the plants have not been able to take advantage of the huge technology gains that have been made in process control during this period. As a result, most of these plants are much less efficient and productive than they could be. One particular area of the plant that is receiving a lot of attention is the feedwater heaters. These systems were put in place to improve efficiency, but most are not operating correctly. This paper will present a case study where one progressive mid-western utility decided that enough was enough and implemented a process control audit of their heater systems. The audit clearly pointed out the existing problems with the current process control system. It resulted in a proposal for the implementation of a state of the art, digital distributed process control system for the heaters along with a complete upgrade of the level controls and field devices that will stabilize heater levels, resulting in significant efficiency gains and lower maintenance bills. Overall the payback period for this investment should be less than 6 months and the plant is now looking for more opportunities that can provide even bigger gains. (author)

  8. REVA Advanced Fuel Design and Codes and Methods - Increasing Reliability, Operating Margin and Efficiency in Operation

    Energy Technology Data Exchange (ETDEWEB)

    Frichet, A.; Mollard, P.; Gentet, G.; Lippert, H. J.; Curva-Tivig, F.; Cole, S.; Garner, N.

    2014-07-01

    Since three decades, AREVA has been incrementally implementing upgrades in the BWR and PWR Fuel design and codes and methods leading to an ever greater fuel efficiency and easier licensing. For PWRs, AREVA is implementing upgraded versions of its HTP{sup T}M and AFA 3G technologies called HTP{sup T}M-I and AFA3G-I. These fuel assemblies feature improved robustness and dimensional stability through the ultimate optimization of their hold down system, the use of Q12, the AREVA advanced quaternary alloy for guide tube, the increase in their wall thickness and the stiffening of the spacer to guide tube connection. But an even bigger step forward has been achieved a s AREVA has successfully developed and introduces to the market the GAIA product which maintains the resistance to grid to rod fretting (GTRF) of the HTP{sup T}M product while providing addition al thermal-hydraulic margin and high resistance to Fuel Assembly bow. (Author)

  9. Evaluation and improvement of nondestructive evaluation reliability for inservice inspection of light water reactors

    International Nuclear Information System (INIS)

    Bates, D.J.; Deffenbaugh, J.D.; Good, M.S.; Heasler, P.G.; Mart, G.A.; Simonen, F.A.; Spanner, J.C.; Taylor, T.T.; Van Fleet, L.G.

    1987-01-01

    The Evaluation and Improvement of NDE Reliability for Inservice Inspection (ISI) of Light Water Reactors (NDE Reliability) Program at Pacific Northwest Laboratory (PNL) was established to determine the reliability of current ISI techniques and to develop recommendations that will ensure a suitably high inspection reliability. The objectives of this NRC program are to: determine the reliability of ultrasonic ISI performed on commercial light-water reactor (LWR) primary systems, using probabilistic fracture mechanics analysis, determine the impact of NDE unreliability on system safety and determine the level of inspection reliability required to ensure a suitably low failure probability, evaluate the degree of reliability improvement that could be achieved using improved and advanced NDE techniques, based on material properties, service conditions, and NDE uncertainties, recommend revisions to ASME Code, Section XI, and Regulatory Requirements that will ensure suitably low failure probabilities. The scope of this program is limited to ISI of primary systems; the results and recommendations may also be applicable to Class II piping systems

  10. Improved Reliability-Based Optimization with Support Vector Machines and Its Application in Aircraft Wing Design

    Directory of Open Access Journals (Sweden)

    Yu Wang

    2015-01-01

    Full Text Available A new reliability-based design optimization (RBDO method based on support vector machines (SVM and the Most Probable Point (MPP is proposed in this work. SVM is used to create a surrogate model of the limit-state function at the MPP with the gradient information in the reliability analysis. This guarantees that the surrogate model not only passes through the MPP but also is tangent to the limit-state function at the MPP. Then, importance sampling (IS is used to calculate the probability of failure based on the surrogate model. This treatment significantly improves the accuracy of reliability analysis. For RBDO, the Sequential Optimization and Reliability Assessment (SORA is employed as well, which decouples deterministic optimization from the reliability analysis. The improved SVM-based reliability analysis is used to amend the error from linear approximation for limit-state function in SORA. A mathematical example and a simplified aircraft wing design demonstrate that the improved SVM-based reliability analysis is more accurate than FORM and needs less training points than the Monte Carlo simulation and that the proposed optimization strategy is efficient.

  11. Implementation of an Improved Safe Operating Envelope

    International Nuclear Information System (INIS)

    Prime, Robyn; McIntyre, Mark; Reeves, David

    2008-01-01

    This paper is a continuation of the paper presented at IYNC 2004 on 'The Definition of a Safe Operating Envelope'. The current paper concentrates on the implementation process of the Safe Operating Envelope employed at the Point Lepreau Generating Station. (authors)

  12. Implementation of an Improved Safe Operating Envelope

    Energy Technology Data Exchange (ETDEWEB)

    Prime, Robyn; McIntyre, Mark [NB Power Nuclear, P.O. Box 600, Lepreau, NB (Canada); Reeves, David [Atlantic Nuclear Services Ltd., PO Box 1268 Fredericton, NB (Canada)

    2008-07-01

    This paper is a continuation of the paper presented at IYNC 2004 on 'The Definition of a Safe Operating Envelope'. The current paper concentrates on the implementation process of the Safe Operating Envelope employed at the Point Lepreau Generating Station. (authors)

  13. Improving Organisational Effectiveness of Coalition Operations

    NARCIS (Netherlands)

    Bisig, E.; Ann-Renée; Hof, T.; Seiler, S.; Yanakiev, Y.

    2010-01-01

    Transformation of military operations demands new tools to support the performance of coalition forces in multinational operations. This paper contributes to one of the fundamental objectives of SAS-081/RSY, namely to the objective to share experience from the implementation of methods and tools and

  14. Operational reliability of the GPK and the 4PP-2 heading machines

    Energy Technology Data Exchange (ETDEWEB)

    Ivanov, N.A.; Demchenko, N.T.

    1985-09-01

    Reliability of the GPK and 4PP-2 heading machines used in 98 development workings in 40 coal mines is analyzed. Failure analysis was based on records of 199 heading machines after overhauls. The mean-time-between-failures of the GPK and the 4PP-2 was 270 min (93 t) and 155 min (35 t), availability coefficient was 0.83 and 0.77 respectively. Reliability of the GPK on the average was higher than that of the 4PP-2. The mean-time-to-overhaul of the GPK was 17.7 months (54,000 t), of the 4PP-2 - 18 months (59,000 t). Time between overhauls in the case of the GPK was 14 months (47,200 t), in the case of the 4PP-2 it was 14.5 months (38,300 t). During the 17.7 months between overhauls the GPK failed 580 times, the repair operations lasted 530 h. During the 18 month time to overhaul the 4PP-2 failed 1600 times, the repair operations lasted 1300 h. Reliability of major elements of the 2 heading machines is analyzed: cutters, materials handling equipment, electrical equipment, hydraulic systems, dust suppression systems, etc.

  15. Reliability analysis of meteorological data registered during nuclear power plant normal operation

    International Nuclear Information System (INIS)

    Amado, V.; Ulke, A.; Marino, B.; Thomas, L.

    2011-01-01

    The atmosphere is the environment in which gaseous radioactive discharges from nuclear power plants are transported. It is therefore essential to have reliable meteorological information to characterize the dispersion and feed evaluation models and radiological environmental impact during normal operation of the plant as well as accidental releases. In this way it is possible to determine the effects on the environment and in humans. The basic data needed to represent adequately the local weather include air temperature, wind speed and direction, rainfall, humidity and pressure. On the other hand, specific data consistent with the used model is required to determine the turbulence, for instance, radiation, cloud cover and vertical temperature gradient. It is important that the recorded data are representative of the local meteorology. This requires, first, properly placed instruments, that should be kept in operation and undergoing maintenance on a regular basis. Second, but equally substantial, a thorough analysis of its reliability must be performed prior to storage and/or data processing. In this paper we present the main criteria to consider choosing the location of a meteorological tower in the area of a nuclear power plant and propose a methodology for assessing the reliability of recorded data. The methodology was developed from the analysis of meteorological data registered in nuclear power plants in Argentina. (authors) [es

  16. FACTORS INFLUENCING HUMAN RELIABILITY OF HIGH TEMPERATURE GAS COOLED REACTOR OPERATION

    Directory of Open Access Journals (Sweden)

    Sigit Santoso

    2016-10-01

    ABSTRAK Peran dan tindakan operator pada reaktor berpendingin gas akan berbeda dengan peran operator pada operasi tipe reaktor lain. Analisis unjuk kerja operator dan faktor yang berpengaruh dapat dilakukan secara komprehensif melalui analisis keandalan manusia(HRA. Melalui HRA dampak dari kesalahan manusia pada sistem maupun cara untuk mengurangi dampak dan frekuensi kesalahan dapat diketahui. Makalah membahas faktor yang berpengaruh pada tindakan operator, yaitu pada kejadian kecelakaan pendingin reaktor gas bersuhu tinggi-HTGR. Analisis untuk kualifikasi faktor pembentuk kinerja(PSF dilakukan berdasarkan kurva keandalan fungsi waktu, dan metode keandalan manusia yang dikembangkan berdasar pada aspek kognitif yaitu Cognitive Reliability and Error Analysis Method (CREAM. Hasil analisis berdasar kurva keandalan fungsi waktu menunjukkan komponen waktu berkontribusi positif pada peningkatan keandalan operator (PSF<1 pada kondisi semua fitur keselamatan berfungsi sesuai rancangan. Sedangkan pada metoda analisis dengan pendekatan kognitif CREAM diketahui selain faktor ketersediaan waktu, faktor pelatihan dan rancangan HMI juga berkontribusi meningkatkan keandalan operator. Faktor pembentuk kinerja keseluruhan diketahui sebesar 0,25 dengan faktor kontribusi positif dominan atau berpengaruh pada penurunan kesalahan manusia adalah ketersediaan waktu (PSF=0,01, dan faktor kontribusi negatif dominan adalah prosedur dan siklus kerja (PSF=5. Nilai PSF tersebut sebagai faktor pengali dalam perhitungan probabilitas kesalahan manusia. Analisis faktor pembentuk kinerja perlu dikembangkan pada skenario kejadian lain untuk selanjutnya digunakan untuk perhitungan dan analisis keandalan manusia yang komprehensif dan perancangan sistem interaksi manusia mesin di ruang kendali. Kata kunci: PSF, HTGR, operator, ruang kendali, keandalan manusia

  17. Reliability analysis of safety systems of nuclear power plant and utility experience with reliability safeguarding of systems during specified normal operation

    International Nuclear Information System (INIS)

    Balfanz, H.P.

    1989-01-01

    The paper gives an outline of the methods applied for reliability analysis of safety systems in nuclear power plant. The main tasks are to check the system design for detection of weak points, and to find possibilities of optimizing the strategies for inspection, inspection intervals, maintenance periods. Reliability safeguarding measures include the determination and verification of the broundary conditions of the analysis with regard to the reliability parameters and maintenance parameters used in the analysis, and the analysis of data feedback reflecting the plant response during operation. (orig.) [de

  18. A Chronological Reliability Model to Assess Operating Reserve Allocation to Wind Power Plants: Preprint

    International Nuclear Information System (INIS)

    Milligan, M. R.

    2001-01-01

    As the use of wind power plants increases worldwide, it is important to understand the effect these power sources have on the operations of the grid. This paper focuses on the operating reserve impact of wind power plants. Many probabilistic methods have been applied to power system analysis, and some of these are the basis of reliability analysis. This paper builds on a probabilistic technique to allocate the operating reserve burden among power plants in the grid. The method was originally posed by Strbac and Kirschen[1] and uses an allocation that prorates the reserve burden based on expected energy not delivered. Extending this method to include wind power plants allows the reserve burden to be allocated among different plants using the same method, yet incorporates information about the intermittent nature of wind power plants

  19. On-line determination of operating limits incorporating constraint costs and reliability assessment

    International Nuclear Information System (INIS)

    Meisingset, M.; Lovas, G. G.

    1997-01-01

    Problems regarding power system operation following deregulation were discussed. The problems arise as a result of the increased power flow pattern created by deregulation and competitive power markets, resulting in power in excess of N-1, (the capacity of transmission lines available), which in turn creates bottlenecks. In a situation like this, constraint costs and security costs (i.e. the cost of supply interruptions) are incurred as the direct result of the deterministic criteria used in reliability assessment. This paper describes an on-line probabilistic method to determine operating limits based on a trade-off between constraint costs and security costs. The probability of the contingencies depend on the existing weather conditions, which therefore has significant impact on the calculated operating limit. In consequence, the proposed method allows power flow to exceed the N-1 limit during normal weather. Under adverse weather conditions the N-1 criteria should be maintained. 15 refs., 13 figs

  20. Reliability improvement in GaN HEMT power device using a field plate approach

    Science.gov (United States)

    Wu, Wen-Hao; Lin, Yueh-Chin; Chin, Ping-Chieh; Hsu, Chia-Chieh; Lee, Jin-Hwa; Liu, Shih-Chien; Maa, Jer-shen; Iwai, Hiroshi; Chang, Edward Yi; Hsu, Heng-Tung

    2017-07-01

    This study investigates the effect of implementing a field plate on a GaN high-electron-mobility transistor (HEMT) to improve power device reliability. The results indicate that the field plate structure reduces the peak electrical field and interface traps in the device, resulting in higher breakdown voltage, lower leakage current, smaller current collapse, and better threshold voltage control. Furthermore, after high voltage stress, steady dynamic on-resistance and gate capacitance degradation improvement were observed for the device with the field plate. This demonstrates that GaN device reliability can be improved by using the field plate approach.

  1. Hospital operations management: improving organizational efficiency.

    Science.gov (United States)

    2013-08-01

    Reducing operational inefficiencies represents one of the most promising sources of potential savings in hospitals today. Health Forum convened a panel of hospital executives and industry experts to discuss the daunting challenges and big opportunities that lie ahead.

  2. Reliability improvements on Thales RM2 rotary Stirling coolers: analysis and methodology

    Science.gov (United States)

    Cauquil, J. M.; Seguineau, C.; Martin, J.-Y.; Benschop, T.

    2016-05-01

    The cooled IR detectors are used in a wide range of applications. Most of the time, the cryocoolers are one of the components dimensioning the lifetime of the system. The cooler reliability is thus one of its most important parameters. This parameter has to increase to answer market needs. To do this, the data for identifying the weakest element determining cooler reliability has to be collected. Yet, data collection based on field are hardly usable due to lack of informations. A method for identifying the improvement in reliability has then to be set up which can be used even without field return. This paper will describe the method followed by Thales Cryogénie SAS to reach such a result. First, a database was built from extensive expertizes of RM2 failures occurring in accelerate ageing. Failure modes have then been identified and corrective actions achieved. Besides this, a hierarchical organization of the functions of the cooler has been done with regard to the potential increase of its efficiency. Specific changes have been introduced on the functions most likely to impact efficiency. The link between efficiency and reliability will be described in this paper. The work on the two axes - weak spots for cooler reliability and efficiency - permitted us to increase in a drastic way the MTTF of the RM2 cooler. Huge improvements in RM2 reliability are actually proven by both field return and reliability monitoring. These figures will be discussed in the paper.

  3. ANALYSIS OF POWER SYSTEM RELIABILITY IMPROVEMENT FOR 74-BUS RADIAL DISTRIBUTION SYSTEM

    OpenAIRE

    Su Mon Myint*

    2018-01-01

    In Myanmar, electric power system planning is widely constructed because of more and more load growth and facing with failure of electricity, outage problems and system shut-down. Thus, not only making new power system network but also improving reliability of the existing system using suitable methods is very important to provide an adequate supply of electrical energy to its customers as economically and reliably as possible with an acceptable degree of continuity and quality that is design...

  4. Improving patient safety: patient-focused, high-reliability team training.

    Science.gov (United States)

    McKeon, Leslie M; Cunningham, Patricia D; Oswaks, Jill S Detty

    2009-01-01

    Healthcare systems are recognizing "human factor" flaws that result in adverse outcomes. Nurses work around system failures, although increasing healthcare complexity makes this harder to do without risk of error. Aviation and military organizations achieve ultrasafe outcomes through high-reliability practice. We describe how reliability principles were used to teach nurses to improve patient safety at the front line of care. Outcomes include safety-oriented, teamwork communication competency; reflections on safety culture and clinical leadership are discussed.

  5. Optimized work control process to improve safety and reliability in a risk-based and deregulated environment

    International Nuclear Information System (INIS)

    Anderson, Jon G.; Jeffries, Jeffrey D. E.; Mairs, Todd P.; Rahn, Frank J.

    1999-01-01

    This paper provides an overview of strategic models to assist power generating plants to improve their work control processes. These models include mechanisms to continually keep the process up to date. Included in the work control process are elements for system cost/performance analysis, life-cycle maintenance planning, on-line scheduling and look-ahead techniques, and schedule implementation to conduct work on the asset. The paper also discusses how risk management associated with work control issues that effect the safety and reliability, as well as O and M costs, is integrated into this strategy. The work control process is a pervasive and critical element in the successful implementation of operations and work management programs. While providing a method to implement maintenance activities in a cost-effective manner, the work control process improves plant safety and system reliability

  6. The European reliability data system. An organized information exchange on the operation of European nuclear reactors

    International Nuclear Information System (INIS)

    Mancini, G.; Amesz, J.; Bastianini, P.; Capobianchi, S.

    1983-01-01

    The paper revises the aims and objectives of the European Reliability Data System (ERDS), a centralized system collecting and organizing, at European level, information related to the operation of LWRs. The ERDS project was started in 1977 and after a preliminary feasibility study that ended in 1979 is now proceeding towards the final design and implementation stages. ERDS exploits information collected in national data systems and information deriving from single reactor sources. The paper describes first the development of the four data banks constituting the system: Component Event Data Bank, CEDB; Abnormal Occurrences Reporting System, AORS; Operating Unit Status Report, OUSR; and Generic Reliability Parameter Data Bank, GRPDB. Several typical aspects concerning the project are then outlined from the need of homogeneization of data and therefore the need for setting up reference classifications, to the problem of data transcoding and input into the system. Furthermore, the need is stressed of involving much more deeply nuclear power plant operators into the process of data acquisition by providing them with a useful feedback from the data analysis. (author)

  7. Impact of power plant reliability on the choice of operating parameter values

    International Nuclear Information System (INIS)

    Kramer, R.A.

    1985-01-01

    In this thesis, the basic structure for the development of a methodology to evaluate the effect of operating parameters on plant availability and generating system economic dispatch optimization is described. Plant availability is determined by a fault free model. In this model historic, time dependent, component induced forced outage data is utilized as the basis for the calculation of projected plant forced outage rates. The influence of a particular fuel-cycle length at a specific generating station on the operational planning of a multi unit generating system is considered. The basis of the dispatch of units in this analysis is optimal economic operation, i.e., the minimization of the cost of reliability supplying electricity to the system's customers. As a result of the utilization of this technique, a simplified example that considers the choice between a 12- and 18-month fuel cycle length is evaluated in terms of its impact on plant availability, fuel cycle economics and overall optimal generating system economic dispatch. The reliability portion of this methodology is applied to a simplified representation of the recirculation system of a pressurized water reactor nuclear power plant to illustrate the analytic techniques

  8. The purpose and organisation of reliability and risk assessment studies for power plant in operation

    International Nuclear Information System (INIS)

    Ohlmeier, H.

    1989-01-01

    Upon recommendation of the Reaktorsicherheitskommission RSK, specific, probabilistic safety analyses have to be made within the next few years for every nuclear power plant in operation. The paper deals with the activities and tasks and the necessary organisational preparations to be made for carrying out the studies. A systematic determination of reliability parameters and establishment of suitable computer codes are one of the major tasks in the preparatory phase, and information for further quantification of safety reserves and more plant-specific emergency management plans will be major results of the studies. (orig.) [de

  9. The human factor in operation and maintenance of complex high-reliability systems

    International Nuclear Information System (INIS)

    Ryan, T.G.

    1989-01-01

    Human factors issues in probabilistic risk assessment (PRAs) of complex high-reliability systems are addressed. These PRAs influence system operation and technical support programs such as maintainability, test, and surveillance. Using the U.S. commercial nuclear power industry as the setting, the paper addresses the manner in which PRAs currently treat human performance, the state of quantification methods and source data for analyzing human performance, and the role of human factors specialist in the analysis. The paper concludes with a presentation of TALENT, an emerging concept for fully integrating broad-based human factors expertise into the PRA process, is presented. 47 refs

  10. Reliability of sub-seabed disposal operations for high level waste

    International Nuclear Information System (INIS)

    Sarshar, M.M.

    1985-09-01

    This report describes a study carried out into the reliability of two methods of disposal of heat generating radioactive waste: by drilled emplacement in holes drilled into the ocean sediments, and by the use of penetrators to drive the waste below the ocean floor. The study has concentrated on the risk of events leading to the release of radioactivity to the environment, and also on the hazard to personnel involved in the operation. A Failure Mode, Effects and Criticality Analysis and a Fault Tree Analysis have been used in the assessment, and the relative importance of each contributory factor estimated. (author)

  11. Improving operator quality at Genkai Nuclear Power Plant

    International Nuclear Information System (INIS)

    Kuwano, Takeshi.

    1989-01-01

    Improvement in operator quality, or improvement in an operator's skill and professional knowledge, is of prime importance because of its great influence on safe and steady plant operation. This paper describes the education and training of reactor operators at the Genkai pressurized water reactor nuclear power plant with respect to the following topics: organization of Genkai power plant; education and training program management; training at the Nuclear Training Center; training and education on-site including emergency procedures training, normal operating procedures training, informational study of emergency conditions in existing plants, and all-around training of operators; qualifying tests for supervisors; and operator motivation

  12. Improved methods for operating public transportation services.

    Science.gov (United States)

    2013-03-01

    In this joint project, West Virginia University and the University of Maryland collaborated in developing improved methods for analyzing and managing public transportation services. Transit travel time data were collected using GPS tracking services ...

  13. Improving Organisational Effectiveness of Coalition Operations

    Science.gov (United States)

    2010-04-01

    group processes. New York: John Wiley. (pp. 131- 185). [21] Harpaz, I. (2002). Advantages and disadvantages of telecommuting for the individual... telecommuting arrangements: Worker perception and managerial prescriptions. SAM Advanced Management Journal, 57(3), 35-42. Improving Organisational

  14. The Improvement of Particle Swarm Optimization: a Case Study of Optimal Operation in Goupitan Reservoir

    Science.gov (United States)

    Li, Haichen; Qin, Tao; Wang, Weiping; Lei, Xiaohui; Wu, Wenhui

    2018-02-01

    Due to the weakness in holding diversity and reaching global optimum, the standard particle swarm optimization has not performed well in reservoir optimal operation. To solve this problem, this paper introduces downhill simplex method to work together with the standard particle swarm optimization. The application of this approach in Goupitan reservoir optimal operation proves that the improved method had better accuracy and higher reliability with small investment.

  15. Effect of communication on the reliability of nuclear power plant control room operations - pre study

    International Nuclear Information System (INIS)

    Kettunen, Jari; Pyy, Pekka

    1999-01-01

    The objective of the study presented in this paper is to investigate communication practices and their impact on human reliability and plant safety in a nuclear power plant environment. The study aims at developing a general systems approach towards the issue. The ultimate goal of the study is to contribute to the development of probabilistic safety assessment methodologies in the area of communications and crew co-operation. This paper outlines the results of the pre-study. The study is based on the use and further development of different modelling techniques and the application of generic systems engineering as well as crew resource management (CRM) principles. The results so far include a concise literature review on communication and crew performance, a presentation of some potential theoretical concepts and approaches for studying communication in relation to organisational reliability, causal failure sequences and human failures mechanisms, and an introduction of a General Communications Model (GCM) that is presented as a promising approach for studying the reliability and adequacy of communication transactions. Finally, some observations and recommendation concerning next phases of the study are made (author) (ml)

  16. Investigation of the impact of main control room digitalization on operators cognitive reliability in nuclear power plants.

    Science.gov (United States)

    Zhou, Yong; Mu, Haiying; Jiang, Jianjun; Zhang, Li

    2012-01-01

    Currently, there is a trend in nuclear power plants (NPPs) toward introducing digital and computer technologies into main control rooms (MCRs). Safe generation of electric power in NPPs requires reliable performance of cognitive tasks such as fault detection, diagnosis, and response planning. The digitalization of MCRs has dramatically changed the whole operating environment, and the ways operators interact with the plant systems. If the design and implementation of the digital technology is incompatible with operators' cognitive characteristics, it may have negative effects on operators' cognitive reliability. Firstly, on the basis of three essential prerequisites for successful cognitive tasks, a causal model is constructed to reveal the typical human performance issues arising from digitalization. The cognitive mechanisms which they impact cognitive reliability are analyzed in detail. Then, Bayesian inference is used to quantify and prioritize the influences of these factors. It suggests that interface management and unbalanced workload distribution have more significant impacts on operators' cognitive reliability.

  17. Post-event human decision errors: operator action tree/time reliability correlation

    Energy Technology Data Exchange (ETDEWEB)

    Hall, R E; Fragola, J; Wreathall, J

    1982-11-01

    This report documents an interim framework for the quantification of the probability of errors of decision on the part of nuclear power plant operators after the initiation of an accident. The framework can easily be incorporated into an event tree/fault tree analysis. The method presented consists of a structure called the operator action tree and a time reliability correlation which assumes the time available for making a decision to be the dominating factor in situations requiring cognitive human response. This limited approach decreases the magnitude and complexity of the decision modeling task. Specifically, in the past, some human performance models have attempted prediction by trying to emulate sequences of human actions, or by identifying and modeling the information processing approach applicable to the task. The model developed here is directed at describing the statistical performance of a representative group of hypothetical individuals responding to generalized situations.

  18. Post-event human decision errors: operator action tree/time reliability correlation

    International Nuclear Information System (INIS)

    Hall, R.E.; Fragola, J.; Wreathall, J.

    1982-11-01

    This report documents an interim framework for the quantification of the probability of errors of decision on the part of nuclear power plant operators after the initiation of an accident. The framework can easily be incorporated into an event tree/fault tree analysis. The method presented consists of a structure called the operator action tree and a time reliability correlation which assumes the time available for making a decision to be the dominating factor in situations requiring cognitive human response. This limited approach decreases the magnitude and complexity of the decision modeling task. Specifically, in the past, some human performance models have attempted prediction by trying to emulate sequences of human actions, or by identifying and modeling the information processing approach applicable to the task. The model developed here is directed at describing the statistical performance of a representative group of hypothetical individuals responding to generalized situations

  19. Assessment of reliability and maintenance of motor operated valves at Finnish NPPS

    International Nuclear Information System (INIS)

    Laakso, K.; Haenninen, S.; Simola, K.

    1994-01-01

    This paper summarizes two studies on motor operated valve (MOV) failure and maintenance experiences in Finnish nuclear power plants. In the first study, described in section 2 of this paper, the failure reports of MOVs at Finnish BWR units from a nine years' time period were analyzed in a systematic way. The dominant failure mechanisms were identified and time-dependencies in failure occurrence were studied. This study initiated an experience based reliability centered maintenance (RCM) analysis of motor operated valve drives, which is summarized in chapter 3 of this paper. The RCM analysis resulted in the identification and proposal of the most suitable and effective maintenance tasks for consideration. 9 refs, 3 figs, 1 tab

  20. Device Performance and Reliability Improvements of AlGaBN/GaN/Si MOSFET

    Science.gov (United States)

    2016-02-04

    AFRL-AFOSR-JP-TR-2016-0037 Device Performance and Reliablity Improvements of AlGaBN/GaN/Si MOSFET Robert Wallace UNIVERSITY OF TEXAS AT DALLAS Final...GaN/Si MOSFET 5a.  CONTRACT NUMBER 5b.  GRANT NUMBER FA2386-14-1-4069 5c.  PROGRAM ELEMENT NUMBER 61102F 6. AUTHOR(S) Robert Wallace 5d.  PROJECT...AOARD Grant FA2386-14-1-4069 Device Performance and Reliability Improvements of AlGaN/GaN/Si MOSFET US 12 month extension (2014 – 2015) for current

  1. Improving accuracy and reliability of 186-keV measurements for unattended enrichment monitoring

    International Nuclear Information System (INIS)

    Ianakiev, Kiril D.; Boyer, Brian D.; Swinhoe, Martyn T.; Moss, Cal E.; Goda, Joetta M.; Favalli, Andrea; Lombardi, Marcie; Paffet, Mark T.; Hill, Thomas R.; MacArthur, Duncan W.; Smith, Morag K.

    2010-01-01

    Improving the quality of safeguards measurements at Gas Centrifuge Enrichment Plants (GCEPs), whilst reducing the inspection effort, is an important objective given the number of existing and new plants that need to be safeguarded. A useful tool in many safeguards approaches is the on-line monitoring of enrichment in process pipes. One aspect of this measurement is a simple, reliable and precise passive measurement of the 186-keV line from 235 U. (The other information required is the amount of gas in the pipe. This can be obtained by transmission measurements or pressure measurements). In this paper we describe our research efforts towards such a passive measurement system. The system includes redundant measurements of the 186-keV line from the gas and separately from the wall deposits. The design also includes measures to reduce the effect of the potentially important background. Such an approach would practically eliminate false alarms and can maintain the operation of the system even with a hardware malfunction in one of the channels. The work involves Monte Carlo modeling and the construction of a proof-of-principle prototype. We will carry out experimental tests with UF 6 gas in pipes with and without deposits in order to demonstrate the deposit correction.

  2. Improvements in valve reliability due to implementation of effective condition monitoring programs

    International Nuclear Information System (INIS)

    Hale, Stan

    2003-01-01

    Modern diagnostic systems for motor-operated valves, pneumatic control valves and checkvalves have facilitated a shift in the maintenance philosophy for valves and actuators in nuclear power plants from schedule based to condition-based maintenance (CBM). This shift enables plant management to focus resources and schedule priority on the plant equipment that warrants attention thereby not wasting resources or increasing the human factors risk on equipment that has not degraded. The most recent initiatives combine condition monitoring with risk/safety insights to focus attention and resonances on the right equipment at the right time consistent with each component's safety-significance. The activities of the ASME working groups responsible for nuclear O and M codes have kept pace with the technology and process improvements necessary to maximize the technical and economic benefits of condition based and risk informed maintenance. This paper discusses adoption of valve condition monitoring in the nuclear power industry, changes to ASME codes and standards during the 90's to facilitate adoption of condition monitoring technology for in-service testing and recent efforts to combine risk insights with condition monitoring strategies to achieve the highest level of valve reliability and nuclear safety without over inflating maintenance cost. (author)

  3. Reliability Analysis of Operation for Cableways by FTA (Fault Tree Analysis Method

    Directory of Open Access Journals (Sweden)

    Sergej Težak

    2010-05-01

    Full Text Available This paper examines the reliability of the operation of cableway systems in Slovenia, which has major impact on the quality of service in the mountain tourism, mainly in wintertime. Different types of cableway installations in Slovenia were captured in a sample and fault tree analysis (FTA was made on the basis of the obtained data. The paper presents the results of the analysis. With these results it is possible to determine the probability of faults of different types of cableways, which types of faults have the greatest impact on the termination of operation, which components of cableways fail most, what is the impact of age of cableways on the occurrence of the faults. Finally, an attempt was made to find if occurrence of faults on individual cableway installation has also impact on traffic on this cableway due to reduced quality of service. KEYWORDS: cableways, aerial ropeways, chairlifts, ski-tows, quality, faults, fault tree analysis, reliability, service quality, winter tourism, mountain tourist centre

  4. Improved 1500 MWe Arabelle begins operation

    International Nuclear Information System (INIS)

    Anon.

    1995-01-01

    Two of the first 1500 MWe steam turbine-generator sets, described as the largest in the world, are undergoing commissioning at the Chooz B PWR nuclear power station in France. A number of design improvements have been made over the previous generation of 1350 MWe turbines, a process which will continue. (Author)

  5. Cost and operational acceptability improvements to gasifiers

    Energy Technology Data Exchange (ETDEWEB)

    Connor, A.

    2003-07-01

    This work reports on the operation of two gasifiers by Biomass Engineering Ltd. in Northern Ireland, and the simplification of their gas conditioning system. Details are given of the high tar destruction levels achieved, the locally available wood waste and pallet wood, and the use of a back-pulsable dry ceramic filtration system for removing trace organics and particulates from the resulting gas prior to gas cooling, final filtration and use in a gas engine. The results of a techno-economic assessment of the original scrubbing system and the new ceramic filtration system indicating cost savings are presented. Further work to optimise the parameters of the filters is planned.

  6. The performance shaping factors influence analysis on the human reliability for NPP operation

    International Nuclear Information System (INIS)

    Farcasiu, M.; Nitoi, M.; Apostol, M.; Florescu, G.

    2008-01-01

    The Human Reliability Analysis (HRA) is an important step in Probabilistic Safety Assessment (PSA) studies and offers an advisability for concrete improvement of the man - machine - organization interfaces, reliability and safety. The goals of this analysis are to obtain sufficient details in order to understand and document all-important factors that affect human performance. The purpose of this paper is to estimate the human errors probabilities in view of the negative or positive effect of the human performance shaping factors (PSFs) for the mitigation of the initiating events which could occur in Nuclear Power Plant (NPP). Using THERP and SPAR-H methods, an analysis model of PSFs influence on the human reliability is performed. This model is applied to more important activities, that are necessary to mitigate 'one steam generator tube failure' event at Cernavoda NPP. The results are joint human error probabilities (JHEP) values estimated for the following situations: without regarding to PSFs influence; with PSFs in specific conditions; with PSFs which could have only positive influence and with PSFs which could have only negative influence. In addition, PSFs with negative influence were identified and using the DOE method, the necessary activities for changing negative influence were assigned. (authors)

  7. Improving motor reliability in nuclear power plants: Volume 1, Performance evaluation and maintenance practices

    International Nuclear Information System (INIS)

    Subudhi, M.; Gunther, W.E.; Taylor, J.H.; Sugarman, A.C.; Sheets, M.W.

    1987-11-01

    This report constitutes the first of the three volumes under this NUREG. The report presents recommendations for developing a cost-effective program for performance evaluation and maintenance of electric motors in nuclear power plants. These recommendations are based on current industry practices, available techniques for monitoring degradation in motor components, manufacturer's recommendations, operating experience, and results from two laboratory tests on aged motors. Two laboratory test reports on a small and a large motor are presented in separate volumes of this NUREG. These provide the basis for the various functional indicators recommended for maintenance programs in this report. The overall preventive maintenance program is separated into two broad areas of activity aimed at mitigating the potential effects of equipment aging: Performance Evaluation and Equipment Maintenance. The latter involves actually maintaining the condition of the equipment while the former involves those activities undertaken to monitor degradation due to aging. These monitoring methods are further categorized into periodic testing, surveillance testing, continuous monitoring and inspections. This study focuses on the methods and procedures for performing the above activities to maintain the motors operationally ready in a nuclear facility. This includes an assessment of various functional indicators to determine their suitability for trending to monitor motor component condition. The intrusiveness of test methods and the present state-of-the-art for using the test equipment in a plant environment are discussed. In conclusion, implementation of the information provided in this report, will improve motor reliability in nuclear power plants. The study indicates the kinds of tests to conduct, how and when to conduct them, and to which motors the tests should be applied. 44 refs., 12 figs., 13 tabs

  8. Improvement of operation and maintenance management

    International Nuclear Information System (INIS)

    Hamazaki, Kazushige

    1986-01-01

    The organization for the operation management of nuclear power plants was established by Japanese utilities, and it was shown in the high capacity ratio of nuclear power plants that the establishment of the organization was of value. The utilities have made much effort with the cooperation of regulatory bodies and plant manufacturers so as to be able to ensure the safe, stable operation of nuclear power plants by overcoming various technical and social problems, in order to obtain public confidence. The education and training of the personnel concerned with nuclear power generation are much to do with the special condition of nuclear power development in Japan. The development and history of the education and training of nuclear power staffs in Japanese utilities are reviewed in three phases, initial 1967 ∼ 1971, the period of upgrading the management and the technical level of nuclear power stations 1972 ∼ 1980, and the period of firmly established nuclear power generation thereafter. The important basic policy of the management in Japanese utility companies, the characteristics of the in-house education of staffs based on the basic policy and the education and training of technical staffs are reported. (Kako, I.)

  9. Development of improved technology for decommissioning operations

    International Nuclear Information System (INIS)

    Allen, R.P.

    1982-07-01

    This paper describes the technology development activities conducted at Pacific Northwest Laboratory under US Department of Energy sponsorship to help ensure the availability of safe, cost-effective and environmentally sound decommissioning technology for radioactively contaminated facilities. These improved decommissioning technologies include techniques for the removal of contaminated concrete surfaces and coatings, adaptation of electropolishing and vibratory finishing decontamination techniques for field decommissioning applications, development of sensitive field instrumentation and methods for the monitoring of large surface areas, techniques for the field sectioning of contaminated components, improved contamination-stabilizing coatings and application methods, and development of a small solidification system for the field solidification of liquid waste. The results of cost/benefit studies for some of these technologies are also reported

  10. Improving the reliability of the prognosis of radiation exposures using data assimilation

    International Nuclear Information System (INIS)

    Twenhoefel, C.J.W.; Eleveld, H.

    2003-01-01

    Full text: During large-scale nuclear accidents quantitative risk estimates usually underlie a countermeasure strategy. Because of the overwhelming social and economical impact of countermeasures not only the speed but also the reliability of the underlying calculations are of prime importance. Real-time atmospheric dispersion models are an important tool to support the decision-makers with spatial and temporal information on the dispersion forecast and the extent of the expected contamination. Due to the stochastic and chaotic nature of the atmosphere the real-time calculation of air dispersion is quite complicated. The accuracy of the calculated spatial and temporal distributions of air concentration, deposition and the corresponding radiation levels is limited due to uncertainties in the applied dispersion algorithms, limitations in knowledge and availability of atmospheric input data and knowledge of the release and the release conditions during an emergency. To improve the prognosis of the radiation exposure it is envisaged to use the on-line data of the National Radioactivity Monitoring Network. In a first step the monitored gamma radiation levels are related to the calculated external radiation levels from source term estimates based on the plant status. In the next step both the results of air dispersion model calculations and the data of the monitoring network are compared using RIVM's dispersion model validation tool [1-2]. From this a quantitative measure for the agreement between a model run and a particular measurement set can be deduced. This will be followed by a data assimilation technique based an RIVM's validation tool which provides an improved reliability of the prognosis when compared to intermediate, i.e. previous model runs. An uncertainty and sensitivity analysis of the air dispersion model must identify the relevant input parameters. In the absence of elevated levels on our monitoring network the Kincaid data set will be used to demonstrate

  11. An intercomparison of approaches for improving operational seasonal streamflow forecasts

    Science.gov (United States)

    Mendoza, Pablo A.; Wood, Andrew W.; Clark, Elizabeth; Rothwell, Eric; Clark, Martyn P.; Nijssen, Bart; Brekke, Levi D.; Arnold, Jeffrey R.

    2017-07-01

    For much of the last century, forecasting centers around the world have offered seasonal streamflow predictions to support water management. Recent work suggests that the two major avenues to advance seasonal predictability are improvements in the estimation of initial hydrologic conditions (IHCs) and the incorporation of climate information. This study investigates the marginal benefits of a variety of methods using IHCs and/or climate information, focusing on seasonal water supply forecasts (WSFs) in five case study watersheds located in the US Pacific Northwest region. We specify two benchmark methods that mimic standard operational approaches - statistical regression against IHCs and model-based ensemble streamflow prediction (ESP) - and then systematically intercompare WSFs across a range of lead times. Additional methods include (i) statistical techniques using climate information either from standard indices or from climate reanalysis variables and (ii) several hybrid/hierarchical approaches harnessing both land surface and climate predictability. In basins where atmospheric teleconnection signals are strong, and when watershed predictability is low, climate information alone provides considerable improvements. For those basins showing weak teleconnections, custom predictors from reanalysis fields were more effective in forecast skill than standard climate indices. ESP predictions tended to have high correlation skill but greater bias compared to other methods, and climate predictors failed to substantially improve these deficiencies within a trace weighting framework. Lower complexity techniques were competitive with more complex methods, and the hierarchical expert regression approach introduced here (hierarchical ensemble streamflow prediction - HESP) provided a robust alternative for skillful and reliable water supply forecasts at all initialization times. Three key findings from this effort are (1) objective approaches supporting methodologically

  12. An intercomparison of approaches for improving operational seasonal streamflow forecasts

    Directory of Open Access Journals (Sweden)

    P. A. Mendoza

    2017-07-01

    Full Text Available For much of the last century, forecasting centers around the world have offered seasonal streamflow predictions to support water management. Recent work suggests that the two major avenues to advance seasonal predictability are improvements in the estimation of initial hydrologic conditions (IHCs and the incorporation of climate information. This study investigates the marginal benefits of a variety of methods using IHCs and/or climate information, focusing on seasonal water supply forecasts (WSFs in five case study watersheds located in the US Pacific Northwest region. We specify two benchmark methods that mimic standard operational approaches – statistical regression against IHCs and model-based ensemble streamflow prediction (ESP – and then systematically intercompare WSFs across a range of lead times. Additional methods include (i statistical techniques using climate information either from standard indices or from climate reanalysis variables and (ii several hybrid/hierarchical approaches harnessing both land surface and climate predictability. In basins where atmospheric teleconnection signals are strong, and when watershed predictability is low, climate information alone provides considerable improvements. For those basins showing weak teleconnections, custom predictors from reanalysis fields were more effective in forecast skill than standard climate indices. ESP predictions tended to have high correlation skill but greater bias compared to other methods, and climate predictors failed to substantially improve these deficiencies within a trace weighting framework. Lower complexity techniques were competitive with more complex methods, and the hierarchical expert regression approach introduced here (hierarchical ensemble streamflow prediction – HESP provided a robust alternative for skillful and reliable water supply forecasts at all initialization times. Three key findings from this effort are (1 objective approaches supporting

  13. Cycle chemistry monitoring system as means of improving the reliability of the equipment at the power plants

    Science.gov (United States)

    Yegoshina, O. V.; Voronov, V. N.; Yarovoy, V. O.; Bolshakova, N. A.

    2017-11-01

    There are many problems in domestic energy at the present that require urgent solutions in the near future. One of these problems - the aging of the main and auxiliary equipment. Wear of equipment is the cause of decrease reliability and efficiency of power plants. Reliability of the equipment are associated with the introduction of cycle chemistry monitoring system. The most damageable equipment’s are boilers (52.2 %), turbines (12.6 %) and heating systems (12.3 %) according to the review of failure rate on the power plants. The most part of the damageability of the boiler is heated surfaces (73.2 %). According to the Russian technical requirements, the monitoring systems are responsible to reduce damageability the boiler heating surfaces and to increase the reliability of the equipment. All power units capacity of over 50 MW are equipped with cycle chemistry monitoring systems in order to maintain water chemistry within operating limits. The main idea of cycle chemistry monitoring systems is to improve water chemistry at power plants. According to the guidelines, cycle chemistry monitoring systems of a single unit depends on its type (drum or once-through boiler) and consists of: 20…50 parameters of on-line chemical analyzers; 20…30 «grab» sample analyses (daily) and about 15…20 on-line monitored operating parameters. The operator of modern power plant uses with many data at different points of steam/water cycle. Operators do not can estimate quality of the cycle chemistry due to the large volume of daily and every shift information and dispersion of data, lack of systematization. In this paper, an algorithm for calculating the quality index developed for improving control the water chemistry of the condensate, feed water and prevent scaling and corrosion in the steam/water cycle.

  14. Early operating and reliability experience with the CEBAF DC magnet power supplies

    International Nuclear Information System (INIS)

    Merz, W.; Flood, R.; Martin, E.J.; O'Sullivan, M.

    1996-01-01

    The CEBAF accelerator is a five pass, recirculating, CW electron linear accelerator. There are a total of nine recirculation arcs connecting the two linacs. Three experimental halls are serviced by the accelerator through separate transport channels. The magnet powering system for CEBAF consists of approximately 2000 independent control channels. About 1850 of these channels are low current, trim magnet power supplies. There are 28 higher power supplies used to energize the major bending elements. Over one hundred, 20 amp, active shunts are used to vary current in selected magnets in the major dipole strings. The majority of the magnetic elements are concentrated in the arcs and transport channels. The correction dipoles, quadrupoles and sextupoles are each powered individually be a dedicated trim power supply channel. The arc and extraction channel dipoles are powered in series strings by the high powered supplies, known locally at CEBAF as 'box power supplies'. Arc loads consist of some 30--40 magnets in series. Transport channel, path length control doglegs and septa box power supplies have loads ranging from 1 to 10 magnets. Shunts are installed on virtually all loads where two or more magnets are in series. At this time, 95% of the power supplies are installed and commissioned. In the past twelve months, beginning in May 1994, approximately 1200 trim magnet power supplies have been checked out. During this same period approximately 22 box power supplies and 100 shunts have been made operational. Full operation of the equipment has only been under way since early 1995. While this operation is only just beginning, much has been learned based on the reliability performance seen so far. The remainder of this paper describes the systems mentioned, their reliability problems, the fixes implemented to date, and some plans for the future. 6 refs., 3 tabs

  15. reliability reliability

    African Journals Online (AJOL)

    eobe

    Corresponding author, Tel: +234-703. RELIABILITY .... V , , given by the code of practice. However, checks must .... an optimization procedure over the failure domain F corresponding .... of Concrete Members based on Utility Theory,. Technical ...

  16. Improving the Sharing and Use of Operating Experience Among Pressurized Heavy Water Reactors

    International Nuclear Information System (INIS)

    Llewellyn, Michael D.

    1998-01-01

    Effective use of operating experience is an essential and fundamental aspect of the business of improving safety and reliability of nuclear power plant. Operating experience is considered of such importance, that it is embedded as a fundamental element in the WANO mission statement: 'To maximise the safety and reliability of operation of nuclear power plants by exchanging information and encouraging communication, comparison, and emulation amongst its members'. The exchange of information on plant operating experience and lessons learned from events is at the core of our WANO mission and is an essential element of effective operating experience use. Recognizing this, WANO - AC has joined together with Canadian PHWR operators in a cooperative effort to further strengthen the sharing of the event information, and to facilitate communication of PHWR operating experience worldwide. The content of the paper is: 1. Discussion; 2. Expectation; 3. Improving use of operating experience; 4. Internalizing operating experience; 5. Summary; 6. Attachments. The three attachments deal with: - WANO event reporting guidelines; - Root cause investigation guidelines; - Example prevent events briefing sheet. The paper is completed with the five slides used in the oral presentation

  17. Precision of lumbar intervertebral measurements: does a computer-assisted technique improve reliability?

    Science.gov (United States)

    Pearson, Adam M; Spratt, Kevin F; Genuario, James; McGough, William; Kosman, Katherine; Lurie, Jon; Sengupta, Dilip K

    2011-04-01

    Comparison of intra- and interobserver reliability of digitized manual and computer-assisted intervertebral motion measurements and classification of "instability." To determine if computer-assisted measurement of lumbar intervertebral motion on flexion-extension radiographs improves reliability compared with digitized manual measurements. Many studies have questioned the reliability of manual intervertebral measurements, although few have compared the reliability of computer-assisted and manual measurements on lumbar flexion-extension radiographs. Intervertebral rotation, anterior-posterior (AP) translation, and change in anterior and posterior disc height were measured with a digitized manual technique by three physicians and by three other observers using computer-assisted quantitative motion analysis (QMA) software. Each observer measured 30 sets of digital flexion-extension radiographs (L1-S1) twice. Shrout-Fleiss intraclass correlation coefficients for intra- and interobserver reliabilities were computed. The stability of each level was also classified (instability defined as >4 mm AP translation or 10° rotation), and the intra- and interobserver reliabilities of the two methods were compared using adjusted percent agreement (APA). Intraobserver reliability intraclass correlation coefficients were substantially higher for the QMA technique THAN the digitized manual technique across all measurements: rotation 0.997 versus 0.870, AP translation 0.959 versus 0.557, change in anterior disc height 0.962 versus 0.770, and change in posterior disc height 0.951 versus 0.283. The same pattern was observed for interobserver reliability (rotation 0.962 vs. 0.693, AP translation 0.862 vs. 0.151, change in anterior disc height 0.862 vs. 0.373, and change in posterior disc height 0.730 vs. 0.300). The QMA technique was also more reliable for the classification of "instability." Intraobserver APAs ranged from 87 to 97% for QMA versus 60% to 73% for digitized manual

  18. Investigation of key parameters for the development of reliable ITER baseline operation scenarios using CORSICA

    Science.gov (United States)

    Kim, S. H.; Casper, T. A.; Snipes, J. A.

    2018-05-01

    ITER will demonstrate the feasibility of burning plasma operation by operating DT plasmas in the ELMy H-mode regime with a high ratio of fusion power gain Q ~ 10. 15 MA ITER baseline operation scenario has been studied using CORSICA, focusing on the entry to burn, flat-top burning plasma operation and exit from burn. The burning plasma operation for about 400 s of the current flat-top was achieved in H-mode within the various engineering constraints imposed by the poloidal field coil and power supply systems. The target fusion gain (Q ~ 10) was achievable in the 15 MA ITER baseline operation with a moderate amount of the total auxiliary heating power (~50 MW). It has been observed that the tungsten (W) concentration needs to be maintained low level (n w/n e up to the order of 1.0  ×  10-5) to avoid the radiative collapse and uncontrolled early termination of the discharge. The dynamic evolution of the density can modify the H-mode access unless the applied auxiliary heating power is significantly higher than the H-mode threshold power. Several qualitative sensitivity studies have been performed to provide guidance for further optimizing the plasma operation and performance. Increasing the density profile peaking factor was quite effective in increasing the alpha particle self-heating power and fusion power multiplication factor. Varying the combination of auxiliary heating power has shown that the fusion power multiplication factor can be reduced along with the increase in the total auxiliary heating power. As the 15 MA ITER baseline operation scenario requires full capacity of the coil and power supply systems, the operation window for H-mode access and shape modification was narrow. The updated ITER baseline operation scenarios developed in this work will become a basis for further optimization studies necessary along with the improvement in understanding the burning plasma physics.

  19. Training less-experienced faculty improves reliability of skills assessment in cardiac surgery.

    Science.gov (United States)

    Lou, Xiaoying; Lee, Richard; Feins, Richard H; Enter, Daniel; Hicks, George L; Verrier, Edward D; Fann, James I

    2014-12-01

    Previous work has demonstrated high inter-rater reliability in the objective assessment of simulated anastomoses among experienced educators. We evaluated the inter-rater reliability of less-experienced educators and the impact of focused training with a video-embedded coronary anastomosis assessment tool. Nine less-experienced cardiothoracic surgery faculty members from different institutions evaluated 2 videos of simulated coronary anastomoses (1 by a medical student and 1 by a resident) at the Thoracic Surgery Directors Association Boot Camp. They then underwent a 30-minute training session using an assessment tool with embedded videos to anchor rating scores for 10 components of coronary artery anastomosis. Afterward, they evaluated 2 videos of a different student and resident performing the task. Components were scored on a 1 to 5 Likert scale, yielding an average composite score. Inter-rater reliabilities of component and composite scores were assessed using intraclass correlation coefficients (ICCs) and overall pass/fail ratings with kappa. All components of the assessment tool exhibited improvement in reliability, with 4 (bite, needle holder use, needle angles, and hand mechanics) improving the most from poor (ICC range, 0.09-0.48) to strong (ICC range, 0.80-0.90) agreement. After training, inter-rater reliabilities for composite scores improved from moderate (ICC, 0.76) to strong (ICC, 0.90) agreement, and for overall pass/fail ratings, from poor (kappa = 0.20) to moderate (kappa = 0.78) agreement. Focused, video-based anchor training facilitates greater inter-rater reliability in the objective assessment of simulated coronary anastomoses. Among raters with less teaching experience, such training may be needed before objective evaluation of technical skills. Published by Elsevier Inc.

  20. Human reliability and plant operating efficiency: Are 12-hour work schedules cause for concern?

    International Nuclear Information System (INIS)

    Baker, T.L.

    1992-01-01

    Since the introduction of 12-h shifts to the US nuclear power industry only 8 yr ago, compressed workweek schedules have proliferated among operations departments at a phenomenal rate. Many plants that continue to use 8-h shifts during normal operations routinely change to scheduled 12-h shifts during refueling or maintenance outages. The most critical issue in the use of extended work shifts is whether alertness, physical stamina, or mental performance are compromised to the point of reducing safety or efficiency of nuclear power plant operation. Laboratory and field research sponsored by the National Institute of Occupational Safety and Health suggests that alertness, measured by self-ratings, and mental performance, measured by computer-based performance tests, are impaired on 12-h shifts compared with 8-h shifts. In contrast to these findings, plant operating efficiency and operator performance have been rated as improved in two field studies conducted in operating nuclear power plants (Fast Flux Test Facility, Washington and Ontario Hydro, Canada). A recent Electric Power Research Institute review of nuclear industry experience with 12-h shifts also suggests an overwhelmingly positive rating of 12-h schedules from both control room operators and management

  1. Technology Improvement for the High Reliability LM-2F Launch Vehicle

    Institute of Scientific and Technical Information of China (English)

    QIN Tong; RONG Yi; ZHENG Liwei; ZHANG Zhi

    2017-01-01

    The Long March 2F (LM-2F) launch vehicle,the only launch vehicle designed for manned space flight in China,successfully launched the Tiangong 2 space laboratory and the Shenzhou ll manned spaceship into orbits in 2016 respectively.In this study,it introduces the technological improvements for enhancing the reliability of the LM-2F launch vehicle in the aspects of general technology,control system,manufacture and ground support system.The LM2F launch vehicle will continue to provide more contributions to the Chinese Space Station Project with its high reliability and 100% success rate.

  2. Reliability database of IEA-R1 Brazilian research reactor: Applications to the improvement of installation safety

    International Nuclear Information System (INIS)

    Oliveira, P.S.P.; Tondin, J.B.M.; Martins, M.O.; Yovanovich, M.; Ricci Filho, W.

    2010-01-01

    In this paper the main features of the reliability database being developed at Ipen-Cnen/SP for IEA-R1 reactor are briefly described. Besides that, the process for collection and updating of data regarding operation, failure and maintenance of IEA-R1 reactor components is presented. These activities have been conducted by the reactor personnel under the supervision of specialists in Probabilistic Safety Analysis (PSA). The compilation of data and subsequent calculation are based on the procedures defined during an IAEA Coordinated Research Project which Brazil took part in the period from 2001 to 2004. In addition to component reliability data, the database stores data on accident initiating events and human errors. Furthermore, this work discusses the experience acquired through the development of the reliability database covering aspects like improvements in the reactor records as well as the application of the results to the optimization of operation and maintenance procedures and to the PSA carried out for IEA-R1 reactor. (author)

  3. Effect of system workload on operating system reliability - A study on IBM 3081

    Science.gov (United States)

    Iyer, R. K.; Rossetti, D. J.

    1985-01-01

    This paper presents an analysis of operating system failures on an IBM 3081 running VM/SP. Three broad categories of software failures are found: error handling, program control or logic, and hardware related; it is found that more than 25 percent of software failures occur in the hardware/software interface. Measurements show that results on software reliability cannot be considered representative unless the system workload is taken into account. The overall CPU execution rate, although measured to be close to 100 percent most of the time, is not found to correlate strongly with the occurrence of failures. Possible reasons for the observed workload failure dependency, based on detailed investigations of the failure data, are discussed.

  4. Life management and operational experience feedback - tools to enhance safety and reliability of the NPP

    International Nuclear Information System (INIS)

    Mach, P.

    1997-01-01

    Preparation has started of the Temelin power plant centralized equipment database. Principles of reliability centered maintenance are studied, and use of these activities will be made in the Plant Ageing Management Programme. The aims of the Programme are as follows: selection of important components subject to ageing, data collection, determination of dominant stressors, development, selection and validation of ageing evaluation methods, setup of experience feedback, determination of responsibilities, methodologies and strategy, elaboration of programme procedures and documentation, and maintenance of programme flexibility. Pilot studies of component ageing are under way: for the reactor pressure vessel, steam generator, pressurizer, piping, ECCS and cables. The organizational structure of the Operational Experience Feedback system is described, as are the responsibility of staff and sources of information. (M.D.)

  5. Embedded Sensors and Controls to Improve Component Performance and Reliability Conceptual Design Report

    Energy Technology Data Exchange (ETDEWEB)

    Kisner, R.; Melin, A.; Burress, T.; Fugate, D.; Holcomb, D.; Wilgen, J.; Miller, J.; Wilson, D.; Silva, P.; Whitlow, L.; Peretz, F.

    2012-09-15

    The objective of this project is to demonstrate improved reliability and increased performance made possible by deeply embedding instrumentation and controls (I&C) in nuclear power plant (NPP) components and systems. The project is employing a highly instrumented canned rotor, magnetic bearing, fluoride salt pump as its I&C technology demonstration platform. I&C is intimately part of the basic millisecond-by-millisecond functioning of the system; treating I&C as an integral part of the system design is innovative and will allow significant improvement in capabilities and performance. As systems become more complex and greater performance is required, traditional I&C design techniques become inadequate and more advanced I&C needs to be applied. New I&C techniques enable optimal and reliable performance and tolerance of noise and uncertainties in the system rather than merely monitoring quasistable performance. Traditionally, I&C has been incorporated in NPP components after the design is nearly complete; adequate performance was obtained through over-design. By incorporating I&C at the beginning of the design phase, the control system can provide superior performance and reliability and enable designs that are otherwise impossible. This report describes the progress and status of the project and provides a conceptual design overview for the platform to demonstrate the performance and reliability improvements enabled by advanced embedded I&C.

  6. Evaluation of Smart Grid Technologies Employed for System Reliability Improvement: Pacific Northwest Smart Grid Demonstration Experience

    Energy Technology Data Exchange (ETDEWEB)

    Agalgaonkar, Yashodhan P.; Hammerstrom, Donald J.

    2017-06-01

    The Pacific Northwest Smart Grid Demonstration (PNWSGD) was a smart grid technology performance evaluation project that included multiple U.S. states and cooperation from multiple electric utilities in the northwest region. One of the local objectives for the project was to achieve improved distribution system reliability. Toward this end, some PNWSGD utilities automated their distribution systems, including the application of fault detection, isolation, and restoration and advanced metering infrastructure. In light of this investment, a major challenge was to establish a correlation between implementation of these smart grid technologies and actual improvements of distribution system reliability. This paper proposes using Welch’s t-test to objectively determine and quantify whether distribution system reliability is improving over time. The proposed methodology is generic, and it can be implemented by any utility after calculation of the standard reliability indices. The effectiveness of the proposed hypothesis testing approach is demonstrated through comprehensive practical results. It is believed that wider adoption of the proposed approach can help utilities to evaluate a realistic long-term performance of smart grid technologies.

  7. Improving operational flood forecasting through data assimilation

    Science.gov (United States)

    Rakovec, Oldrich; Weerts, Albrecht; Uijlenhoet, Remko; Hazenberg, Pieter; Torfs, Paul

    2010-05-01

    Accurate flood forecasts have been a challenging topic in hydrology for decades. Uncertainty in hydrological forecasts is due to errors in initial state (e.g. forcing errors in historical mode), errors in model structure and parameters and last but not least the errors in model forcings (weather forecasts) during the forecast mode. More accurate flood forecasts can be obtained through data assimilation by merging observations with model simulations. This enables to identify the sources of uncertainties in the flood forecasting system. Our aim is to assess the different sources of error that affect the initial state and to investigate how they propagate through hydrological models with different levels of spatial variation, starting from lumped models. The knowledge thus obtained can then be used in a data assimilation scheme to improve the flood forecasts. This study presents the first results of this framework and focuses on quantifying precipitation errors and its effect on discharge simulations within the Ourthe catchment (1600 km2), which is situated in the Belgian Ardennes and is one of the larger subbasins of the Meuse River. Inside the catchment, hourly rain gauge information from 10 different locations is available over a period of 15 years. Based on these time series, the bootstrap method has been applied to generate precipitation ensembles. These were then used to simulate the catchment's discharges at the outlet. The corresponding streamflow ensembles were further assimilated with observed river discharges to update the model states of lumped hydrological models (R-PDM, HBV) through Residual Resampling. This particle filtering technique is a sequential data assimilation method and takes no prior assumption of the probability density function for the model states, which in contrast to the Ensemble Kalman filter does not have to be Gaussian. Our further research will be aimed at quantifying and reducing the sources of uncertainty that affect the initial

  8. Reliability evaluation of emergency AC power systems based on operating experience at U.S. nuclear power plants

    Energy Technology Data Exchange (ETDEWEB)

    Baranowsky, P. W. [U.S. Nuclear Regulatory Commission, Washington, DC (United States)

    1986-02-15

    The reliability of emergency AC power Systems has been under study at the U.S. Nuclear Regulatory Commission and by its contractors for several years. This paper provides the results of work recently performed to evaluate past U.S. nuclear power plant emergency AC power System reliability performance using system level data. Operating experience involving multiple diesel generator failures, unavailabilities, and simultaneous occurrences of failures and out of service diesel generators were used to evaluate reliability performance at individual nuclear power plants covering a 9 year period from 1976 through 1984. The number and nature of failures and distributions of reliability evaluation results are provided. The results show that plant specific performance varied considerably during the period with a large number achieving high reliability performance and a smaller number accounting for lower levels of reliability performance. (author)

  9. Beyond redundancy how geographic redundancy can improve service availability and reliability of computer-based systems

    CERN Document Server

    Bauer, Eric; Eustace, Dan

    2012-01-01

    "While geographic redundancy can obviously be a huge benefit for disaster recovery, it is far less obvious what benefit is feasible and likely for more typical non-catastrophic hardware, software, and human failures. Georedundancy and Service Availability provides both a theoretical and practical treatment of the feasible and likely benefits of geographic redundancy for both service availability and service reliability. The text provides network/system planners, IS/IT operations folks, system architects, system engineers, developers, testers, and other industry practitioners with a general discussion about the capital expense/operating expense tradeoff that frames system redundancy and georedundancy"--

  10. An improved cellular automata model for train operation simulation with dynamic acceleration

    Science.gov (United States)

    Li, Wen-Jun; Nie, Lei

    2018-03-01

    Urban rail transit plays an important role in the urban public traffic because of its advantages of fast speed, large transport capacity, high safety, reliability and low pollution. This study proposes an improved cellular automaton (CA) model by considering the dynamic characteristic of the train acceleration to analyze the energy consumption and train running time. Constructing an effective model for calculating energy consumption to aid train operation improvement is the basis for studying and analyzing energy-saving measures for urban rail transit system operation.

  11. Coupled Thermo-Mechanical and Photo-Chemical Degradation Mechanisms that determine the Reliability and Operational Lifetimes for CPV Technologies

    Energy Technology Data Exchange (ETDEWEB)

    Dauskardt, Reinhold H. [Stanford Univ., CA (United States)

    2017-04-30

    This project sought to identify and characterize the coupled intrinsic photo-chemo-mechanical degradation mechanisms that determine the reliability and operational lifetimes for CPV technologies. Over a three year period, we have completed a highly successful program which has developed quantitative metrologies and detailed physics-based degradation models, providing new insight into the fundamental reliability physics necessary for improving materials, creating accelerated testing protocols, and producing more accurate lifetime predictions. The tasks for the program were separated into two focus areas shown in the figure below. Focus Area 1, led by Reinhold Dauskardt and Warren Cai with a primary collaboration with David Miller of NREL, studied the degradation mechanisms present in encapsulant materials. Focus Area 2, led by Reinhold Dauskardt and Ryan Brock with a primary collaboration with James Ermer and Peter Hebert of Spectrolab, studied stress development and degradation within internal CPV device interfaces. Each focus area was productive, leading to several publications, including findings on the degradation of silicone encapsulant under terrestrial UV, a model for photodegradation of silicone encapsulant adhesion, quantification and process tuning of antireflective layers on CPV, and discovery of a thermal cycling degradation mechanism present in metal gridline structures.

  12. Training improves interobserver reliability for the diagnosis of scaphoid fracture displacement.

    Science.gov (United States)

    Buijze, Geert A; Guitton, Thierry G; van Dijk, C Niek; Ring, David

    2012-07-01

    The diagnosis of displacement in scaphoid fractures is notorious for poor interobserver reliability. We tested whether training can improve interobserver reliability and sensitivity, specificity, and accuracy for the diagnosis of scaphoid fracture displacement on radiographs and CT scans. Sixty-four orthopaedic surgeons rated a set of radiographs and CT scans of 10 displaced and 10 nondisplaced scaphoid fractures for the presence of displacement, using a web-based rating application. Before rating, observers were randomized to a training group (34 observers) and a nontraining group (30 observers). The training group received an online training module before the rating session, and the nontraining group did not. Interobserver reliability for training and nontraining was assessed by Siegel's multirater kappa and the Z-test was used to test for significance. There was a small, but significant difference in the interobserver reliability for displacement ratings in favor of the training group compared with the nontraining group. Ratings of radiographs and CT scans combined resulted in moderate agreement for both groups. The average sensitivity, specificity, and accuracy of diagnosing displacement of scaphoid fractures were, respectively, 83%, 85%, and 84% for the nontraining group and 87%, 86%, and 87% for the training group. Assuming a 5% prevalence of fracture displacement, the positive predictive value was 0.23 in the nontraining group and 0.25 in the training group. The negative predictive value was 0.99 in both groups. Our results suggest training can improve interobserver reliability and sensitivity, specificity and accuracy for the diagnosis of scaphoid fracture displacement, but the improvements are slight. These findings are encouraging for future research regarding interobserver variation and how to reduce it further.

  13. Steam generator thermal hydraulic design & functional architecture features and related operational and reliability issues requiring consideration

    International Nuclear Information System (INIS)

    Klarner, R.G.

    2012-01-01

    Proper thermal hydraulic design and functional architecture are critical to successful steam generator operation and long term reliability. The evolution of steam generators has been a gradual learning process that has benefited from continuous industry operational experience (OPEX). Inadequate thermal hydraulic design can lead to numerous degradation mechanisms such as excessive deposition, corrosion, flow and level instabilities, fluid-elastic instabilities and tube wear. The functional architecture determines the health of the tube bundle and the other internals during manufacturing, handling and operation. It also determines thermal performance as well as establishing global thermal-hydraulic characteristics such as water level shrink and swell response. This paper discusses the range of operational and reliability issues and relates them to the thermal hydraulic attributes and functional architecture of steam generators (many SG reliability issues are further discussed in other presentations at this conference). In pursuing such issues, the paper focuses on the four major features of the equipment, identifying in each case the goals and requirements such features must meet. Typical approaches and the means by which such requirements are addressed in current equipment are discussed. The four features are: 1. Tubing Material and Tube Bundle Heat Transfer Performance; a. Two materials are in current use – Alloy 690 TT and Alloy 800. Both are good materials with excellent performance records which serve their owners very well (the reliability attributes of Alloy 800 and 690 are discussed in other papers at this conference). Caution is advised in the supply of any material: – material quality is only assured by what is specified to material suppliers in procurement specifications – i.e. - all the knowledge and research in the world assures nothing if its findings are not reflected in procurement requirements. b. Heat transfer performance in addition to being

  14. REMOTES: reliable and modular telescope solution for seamless operation and monitoring of various observation facilities

    Science.gov (United States)

    Jakubec, M.; Skala, P.; Sedlacek, M.; Nekola, M.; Strobl, J.; Blazek, M.; Hudec, R.

    2012-09-01

    Astronomers often need to put several pieces of equipment together and have to deploy them at a particular location. This task could prove to be a really tough challenge, especially for distant observing facilities with intricate operating conditions, poor communication infrastructure and unreliable power source. To have this task even more complicated, they also expect secure and reliable operation in both attended and unattended mode, comfortable software with user-friendly interface and full supervision over the observation site at all times. During reconstruction of the D50 robotic telescope facility, we faced many of the issues mentioned above. To get rid of them, we based our solution on a flexible group of hardware modules controlling the equipment of the observation site, connected together by the Ethernet network and orchestrated by our management software. This approach is both affordable and powerful enough to fulfill all of the observation requirements at the same time. We quickly figured out that the outcome of this project could also be useful for other observation facilities, because they are probably facing the same issues we have solved during our project. In this contribution, we will point out the key features and benefits of the solution for observers. We will demonstrate how the solution works at our observing location. We will also discuss typical management and maintenance scenarios and how we have supported them in our solution. Finally, the overall architecture and technical aspects of the solution will be presented and particular design and technology decisions will be clarified.

  15. Reliability-Based Planning of Inspection, Operation and Maintenance for Offshore Oil & Gas Structures and Wind Turbines

    DEFF Research Database (Denmark)

    Sørensen, John Dalsgaard

    2011-01-01

    Reliability-based cost-optimal planning of inspection, maintenance and operation has many applications. In this paper applications for planning of inspections for oil & gas jacket structures and of operation and maintenance of offshore wind turbines are described and illustrated by examples....

  16. Development of reliability database for safety-related I and C component based on operating experience of KSNP

    International Nuclear Information System (INIS)

    Jang, S. C.; Han, S. H.; Min, K. R.

    2001-01-01

    Reliability database for safety-related I and C components has been developed, based on domestic operating experience of total 8.63 years from four units-Yonggwang Units 3 and 4, and Ulchin Units 3 and 4. This plant-specific data of safety-related I and C components has compared with operating experience for CE-supplied plants in U.S.A. As a results, we found that on the whole the domestic reliability data was similar to CE-supplied plants in USA, through lots of failures occurred early in the commercial operation were included in our analyses without percolation

  17. Advances in new WWER designs to improve operation and maintenance

    International Nuclear Information System (INIS)

    Dragunov, Y.G.; Ryzhov, S.B.; Podshibiakin, A.K.; Vasilchenko, I.N.; Repin, A.I.; Nikitenko, M.P.; Konoplev, N.P.; Fil, N.S.

    2000-01-01

    Economic operational indices of WWER-type reactors show their competitiveness in all the countries where these reactors operate. Advanced WWERs being designed and constructed now have the improved characteristics of economical efficiency and are more convenient for operation and maintenance. Many technical solutions aimed at improvement of the operational performance are implemented in the design of WWER-1000/V-392 and WWER-640/V-407, and these reactors are the important basis for the nuclear power expansion in Russia. Some of these solutions are considered in the present paper. (author)

  18. Improvements in operational safety performance of the Magnox power stations

    Energy Technology Data Exchange (ETDEWEB)

    Marchese, C.J. [BNFL Magnox Generation, Berkeley (United Kingdom)

    2000-10-01

    In the 43 years since commencement of operation of Calder Hall, the first Magnox power station, there remain eight Magnox stations and 20 reactors still in operation, owned by BNFL Magnox Generation. This paper describes how the operational safety performance of these stations has significantly improved over the last ten years. This has been achieved against a background of commercial competition introduced by privatization and despite the fact that the Magnox base design belongs to the past. Finally, the company's future plans for continued improvements in operational safety performance are discussed. (author)

  19. Attitude Control of Quad-rotor by Improving the Reliability of Multi-Sensor System

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Dong Hyeon; Chong, Kil To [Chon-bok National University, Jeonju (Korea, Republic of); Park, Jong Ho [Seonam University, Namwon (Korea, Republic of); Ryu, Ji Hyoung [ETRI, Daejeon (Korea, Republic of)

    2015-05-15

    This paper presents the results of study for improving the reliability of quadrotor attitude control by applying a multi-sensor along with a data fusion algorithm. First, a mathematical model of the quadrotor dynamics was developed. Then, using the quadrotor mathematical model, simulations were performed using the improved reliability multi-sensor data as the inputs. From the simulation results, we designed a Gimbal-equipped quadrotor system. With the quadrotor in a hover state, we performed experiments according to the angle change of the user's specifications . We then calculated the attitude control data from the actual experimental data. Furthermore, with additional simulations, we verified the performance of the designed quadrotor attitude control system with multiple sensors.

  20. Water chemistry data acquisition, processing, evaluation and diagnostic systems in Light Water Reactors: Future improvement of plant reliability and safety

    International Nuclear Information System (INIS)

    Uchida, S.; Takiguchi, H.; Ishigure, K.

    2006-01-01

    Data acquisition, processing and evaluation systems have been applied in major Japanese PWRs and BWRs to provide (1) reliable and quick data acquisition with manpower savings in plant chemical laboratories and (2) smooth and reliable information transfer among chemists, plant operators, and supervisors. Data acquisition systems in plants consist of automatic and semi-automatic instruments for chemical analyses, e. g., X-ray fluorescence analysis and ion chromatography, while data processing systems consist of PC base-sub-systems, e.g., data storage, reliability evaluation, clear display, and document preparation for understanding the plant own water chemistry trends. Precise and reliable evaluations of water chemistry data are required in order to improve plant reliability and safety. For this, quality assurance of the water chemistry data acquisition system is needed. At the same time, theoretical models are being applied to bridge the gaps between measured water chemistry data and the information desired to understand the interaction of materials and cooling water in plants. Major models which have already been applied for plant evaluation are: (1) water radiolysis models for BWRs and PWRs; (2) crevice radiolysis model for SCC in BWRs; and (3) crevice pH model for SG tubing in PWRs. High temperature water chemistry sensors and automatic plant diagnostic systems have been applied in only restricted areas. ECP sensors are gaining popularity as tools to determine the effects of hydrogen injection in BWR systems. Automatic plant diagnostic systems based on artificial intelligence will be more popular after having sufficient experience with off line diagnostic systems. (author)

  1. Improvements in the consistency of fabrication and the reliability of nuclear fuels through quality assurance

    International Nuclear Information System (INIS)

    Sifferlen, R.

    1976-01-01

    By establishing correlations between rejection level and fabrication parameters, quality assurance can guide corrective action for improving the consistency of fabrication and the reliability of fuel elements. The author cites examples relating to the quality of the uranium in metallic fuels, the influence of the parent metal on the welding of zirconium alloys, the behaviour of the springs inside the cladding during the welding of plugs and the behaviour of uranium oxide pellets. (author)

  2. Assessing motivation for work environment improvements: internal consistency, reliability and factorial structure.

    Science.gov (United States)

    Hedlund, Ann; Ateg, Mattias; Andersson, Ing-Marie; Rosén, Gunnar

    2010-04-01

    Workers' motivation to actively take part in improvements to the work environment is assumed to be important for the efficiency of investments for that purpose. That gives rise to the need for a tool to measure this motivation. A questionnaire to measure motivation for improvements to the work environment has been designed. Internal consistency and test-retest reliability of the domains of the questionnaire have been measured, and the factorial structure has been explored, from the answers of 113 employees. The internal consistency is high (0.94), as well as the correlation for the total score (0.84). Three factors are identified accounting for 61.6% of the total variance. The questionnaire can be a useful tool in improving intervention methods. The expectation is that the tool can be useful, particularly with the aim of improving efficiency of companies' investments for work environment improvements. Copyright 2010 Elsevier Ltd. All rights reserved.

  3. Operational aspects of asynchronous filtering for improved flood forecasting

    Science.gov (United States)

    Rakovec, Oldrich; Weerts, Albrecht; Sumihar, Julius; Uijlenhoet, Remko

    2014-05-01

    Hydrological forecasts can be made more reliable and less uncertain by recursively improving initial conditions. A common way of improving the initial conditions is to make use of data assimilation (DA), a feedback mechanism or update methodology which merges model estimates with available real world observations. The traditional implementation of the Ensemble Kalman Filter (EnKF; e.g. Evensen, 2009) is synchronous, commonly named a three dimensional (3-D) assimilation, which means that all assimilated observations correspond to the time of update. Asynchronous DA, also called four dimensional (4-D) assimilation, refers to an updating methodology, in which observations being assimilated into the model originate from times different to the time of update (Evensen, 2009; Sakov 2010). This study investigates how the capabilities of the DA procedure can be improved by applying alternative Kalman-type methods, e.g., the Asynchronous Ensemble Kalman Filter (AEnKF). The AEnKF assimilates observations with smaller computational costs than the original EnKF, which is beneficial for operational purposes. The results of discharge assimilation into a grid-based hydrological model for the Upper Ourthe catchment in Belgian Ardennes show that including past predictions and observations in the AEnKF improves the model forecasts as compared to the traditional EnKF. Additionally we show that elimination of the strongly non-linear relation between the soil moisture storage and assimilated discharge observations from the model update becomes beneficial for an improved operational forecasting, which is evaluated using several validation measures. In the current study we employed the HBV-96 model built within a recently developed open source modelling environment OpenStreams (2013). The advantage of using OpenStreams (2013) is that it enables direct communication with OpenDA (2013), an open source data assimilation toolbox. OpenDA provides a number of algorithms for model calibration

  4. Contribution of materials investigations and operating experience of reactor vessel internals to PWRs' safety, performance and reliability

    International Nuclear Information System (INIS)

    Lemaire, E.; Monteil, N.; Jardin, N.; Doll, M.

    2015-01-01

    The Reactor Pressure Vessel Internals (RVI) include all the components inside the pressure vessel, except the nuclear fuel, the rod cluster assemblies and the instrumentation. The RVI consist of bolted and welded structures that are divided into two sub-assemblies: the upper internals which are removed at every refueling outage and the lower internals which are systematically removed for inspection at every 10-year outage. The main functions of the RVI are to position the core, to support it, and to provide a coolant flow by channeling the fluid. Moreover, the lower internals contribute to a neutron protection of the reactor pressure vessel by absorbing most of the neutron flux from the core. Depending on their location and material composition, the RVI components can face different ageing phenomena, that are actual or potential (such as wear, fatigue, stress corrosion cracking, irradiation assisted stress corrosion cracking, hardening and loss of ductility due to neutron irradiation, irradiation creep and irradiation swelling). EDF has developed a strategy for managing ageing and demonstrating the capacity of the RVI to perform their design functions over 40 years of operation. This overall approach is periodically revisited to take into account the most recent knowledge obtained from the following main topics: Safety Analyses, Research-Development programs, In-Service Inspection (ISI) results, Maintenance programs and Metallurgical Examinations. Based on continuous improvements in those fields, the goal of this paper is to present the way that materials investigations and operating experience obtained on RVI are managed by EDF to improve RVI safety, performance and reliability. It is shown that a perspective of 60 years of operation of RVI components is supported by large Research-Development efforts combined with field experience. (authors)

  5. Active Thermal Control for Reliability Improvement of MOS-gated Power Devices

    DEFF Research Database (Denmark)

    Soldati, Alessandro; Concari, Carlo; Dossena, Fabrizio

    2017-01-01

    reliability and lifetime. These figures can then be improved, which eases the adoption of electrification in markets, such as transportation, where they are still below target values. The proposed ATC method leaves electric load parameters untouched, while acting dynamically on gate parameters, namely voltage...... and resistance. A model-predictive control (MPC) strategy is used to determine the most suitable parameters to use. Simulations of the control scheme are presented first, to predict the potential benefits on temperature swing amplitude, and the consequent improvements in terms of device lifetime are inferred...

  6. Improving operator training and performance through simulator observations

    International Nuclear Information System (INIS)

    Flynn, J.P.

    1987-01-01

    This paper describes the methods and results of INPO observations of simulator training for licensed operators. It discusses the history of the observation program to the present. Effective methods for conducting and documenting simulator observations are discussed. The methods used to analyze the observations is also discussed. The major conclusion of the analysis is that opportunities exist for improvement in the use of emergency operating procedures. Teamwork, communication, and simulator instructor skills are also areas where improvement could be made

  7. LP turbine retrofit modernization: Improvements in performance and operation

    International Nuclear Information System (INIS)

    Groenedaal, J.C.; Fowls, L.G.; Subbiah, R.; Maxwell, B.P.; Persson, B.

    1996-01-01

    Westinghouse Electric Corporation retrofitted six low pressure (LP) nuclear turbine rotors and associated blade path components at Ringhals 1, a 1960's vintage English Electric (GEC) unit located near Varobacka, Sweden, and operated by Vattenfall AB. This achieved significant performance improvements and provided improved mechanical features over the original equipment. This paper, discusses design, manufacture, installation, operation and project coordination. The retrofit processes employed for these units can be applied to any potential customers units

  8. A Simulation Model for Machine Efficiency Improvement Using Reliability Centered Maintenance: Case Study of Semiconductor Factory

    Directory of Open Access Journals (Sweden)

    Srisawat Supsomboon

    2014-01-01

    Full Text Available The purpose of this study was to increase the quality of product by focusing on the machine efficiency improvement. The principle of the reliability centered maintenance (RCM was applied to increase the machine reliability. The objective was to create preventive maintenance plan under reliability centered maintenance method and to reduce defects. The study target was set to reduce the Lead PPM for a test machine by simulating the proposed preventive maintenance plan. The simulation optimization approach based on evolutionary algorithms was employed for the preventive maintenance technique selection process to select the PM interval that gave the best total cost and Lead PPM values. The research methodology includes procedures such as following the priority of critical components in test machine, analyzing the damage and risk level by using Failure Mode and Effects Analysis (FMEA, calculating the suitable replacement period through reliability estimation, and optimizing the preventive maintenance plan. From the result of the study it is shown that the Lead PPM of test machine can be reduced. The cost of preventive maintenance, cost of good product, and cost of lost product were decreased.

  9. Matrix Wings: Continuous Process Improvement an Operator Can Love

    Science.gov (United States)

    2016-09-01

    key processes in our normal operations. In addition to the almost inevitable resistance to change, one of the points of pushback is that members of...Fall 2016 | 9 Matrix Wings Continuous Process Improvement an Operator Can Love Dr. A. J. Briding, Colonel, USAF, Retired Disclaimer: The views and...Operations for the 21st Century (AFSO21), the latest comprehensive effort at finding the right ap- proach for implementing a continuous process

  10. Improvements to science operations at Kitt Peak National Observatory

    Science.gov (United States)

    Bohannan, Bruce

    1998-07-01

    In recent years Kitt Peak National Observatory has undertaken a number of innovative projects to optimize science operations with the suite of telescopes we operate on Kitt Peak, Arizona. Changing scientific requirements and expectations of our users, evolving technology and declining budgets have motivated the changes. The operations improvements have included telescope performance enhancements--with the focus on the Mayall 4-m--modes of observing and scheduling, telescope control and observing systems, planning and communication, and data archiving.

  11. Sustaining Operational Resiliency: A Process Improvement Approach to Security Management

    National Research Council Canada - National Science Library

    Caralli, Richard A

    2006-01-01

    .... Coordinating these efforts to sustain operational resiliency requires a process-oriented approach that can be defined, measured, and actively managed. This report describes the fundamental elements and benefits of a process approach to security and operational resiliency and provides a notional view of a framework for process improvement.

  12. Improved Methodology of Weather Window Prediction for Offshore Operations Based on Probabilities of Operation Failure

    DEFF Research Database (Denmark)

    Gintautas, Tomas; Sørensen, John Dalsgaard

    2017-01-01

    The offshore wind industry is building and planning new wind farms further offshore due to increasing demand on sustainable energy production and already occupied prime resource locations closer to shore. Costs of operation and maintenance, transport and installation of offshore wind turbines...... already contribute significantly to the cost of produced electricity and will continue to increase, due to moving further offshore, if the current techniques of predicting offshore wind farm accessibility are to stay the same. The majority of offshore operations are carried out by specialized ships...... that must be hired for the duration of the operation. Therefore, offshore wind farm accessibility and costs of offshore activities are primarily driven by the expected number of operational hours offshore and waiting times for weather windows, suitable for offshore operations. Having more reliable weather...

  13. Near-misses are an opportunity to improve patient safety: adapting strategies of high reliability organizations to healthcare.

    Science.gov (United States)

    Van Spall, Harriette; Kassam, Alisha; Tollefson, Travis T

    2015-08-01

    Near-miss investigations in high reliability organizations (HROs) aim to mitigate risk and improve system safety. Healthcare settings have a higher rate of near-misses and subsequent adverse events than most high-risk industries, but near-misses are not systematically reported or analyzed. In this review, we will describe the strategies for near-miss analysis that have facilitated a culture of safety and continuous quality improvement in HROs. Near-miss analysis is routine and systematic in HROs such as aviation. Strategies implemented in aviation include the Commercial Aviation Safety Team, which undertakes systematic analyses of near-misses, so that findings can be incorporated into Standard Operating Procedures (SOPs). Other strategies resulting from incident analyses include Crew Resource Management (CRM) for enhanced communication, situational awareness training, adoption of checklists during operations, and built-in redundancy within systems. Health care organizations should consider near-misses as opportunities for quality improvement. The systematic reporting and analysis of near-misses, commonplace in HROs, can be adapted to health care settings to prevent adverse events and improve clinical outcomes.

  14. Engineering, maintenance, and initiatives to improve LAMPF beam availability and system reliability

    International Nuclear Information System (INIS)

    Harris, H.W.; DeHaven, R.A.; Hart, V.E.; Parsons, W.M.; Sturrock, J.C.

    1992-01-01

    Two different requirements are driving engineering studies and hardware development to improve LAMPF. The first is concerned with component and system improvements to increase beam availability during the LAMPF production cycle. Hardware changes in RF, power supplies, and magnets are being implemented to increase mean time between failure and reduce time to replace or repair failed units. A joint LAMPF-Industry project is on-going to improve reliability of RF components. A component test stand is being refurbished to include significant development capability. The second approach includes several changes that will increase the duty factor of the existing accelerator. Major changes are being evaluated for replacing the front end of the accelerator. Other changes improving the high brightness capability could result in a new performance plateau for LAMPF. 2 refs., 2 figs

  15. Engineering, maintenance, and new initiatives to improve LAMPF beam availability and system reliability

    International Nuclear Information System (INIS)

    Harris, H.W.; DeHaven, R.A.; Hart, V.E.; Parsons, W.M.; Sturrock, J.C.

    1992-01-01

    Two different requirements are driving engineering studies and hardware development to improve LAMPF. The first is concerned with component and system improvements to increase beam availability during the LAMPF production cycle. Hardware changes in RF, power supplies, and magnets are being implemented to increase mean time between failure and reduce time to replace or repair failed units. A joint LAMPF-Industry project is on-going to improve reliability of RF components. A component test stand is being refurbished to include significant development capability. The second approach includes several changes that will increase the duty factor of the existing accelerator. Major changes are being evaluated for replacing the front end of the accelerator. Other changes improving high brightness capability could result in a new performance plateau for LAMPF

  16. UAV Research at NASA Langley: Towards Safe, Reliable, and Autonomous Operations

    Science.gov (United States)

    Davila, Carlos G.

    2016-01-01

    Unmanned Aerial Vehicles (UAV) are fundamental components in several aspects of research at NASA Langley, such as flight dynamics, mission-driven airframe design, airspace integration demonstrations, atmospheric science projects, and more. In particular, NASA Langley Research Center (Langley) is using UAVs to develop and demonstrate innovative capabilities that meet the autonomy and robotics challenges that are anticipated in science, space exploration, and aeronautics. These capabilities will enable new NASA missions such as asteroid rendezvous and retrieval (ARRM), Mars exploration, in-situ resource utilization (ISRU), pollution measurements in historically inaccessible areas, and the integration of UAVs into our everyday lives all missions of increasing complexity, distance, pace, and/or accessibility. Building on decades of NASA experience and success in the design, fabrication, and integration of robust and reliable automated systems for space and aeronautics, Langley Autonomy Incubator seeks to bridge the gap between automation and autonomy by enabling safe autonomous operations via onboard sensing and perception systems in both data-rich and data-deprived environments. The Autonomy Incubator is focused on the challenge of mobility and manipulation in dynamic and unstructured environments by integrating technologies such as computer vision, visual odometry, real-time mapping, path planning, object detection and avoidance, object classification, adaptive control, sensor fusion, machine learning, and natural human-machine teaming. These technologies are implemented in an architectural framework developed in-house for easy integration and interoperability of cutting-edge hardware and software.

  17. Operation and reliability of a pneumatic hydrogen pellet injection system on the Joint European Torus

    International Nuclear Information System (INIS)

    Combs, S.K.; Jernigan, T.C.; Baylor, L.R.; Milora, S.L.; Foust, C.R.; Kupschus, P.; Gadeberg, M.; Bailey, W.; Commission of the European Communities, Abingdon

    1989-01-01

    A pneumatic-based, hydrogen isotope pellet injector that was developed at the Oak Ridge National Laboratory for the plasma fueling application on the Joint European Torus (JET) was described at the last Symposium on Fusion Engineering (1987). The injector was installed on JET during 1987 and has since been used in plasma fueling experiments. The injector consists of three independent machine-gun-like mechanisms (nominal pellet sizes of 2.7, 4.0, and 6.0 mm in diameter), and it features repetitive operation (1-5 Hz) for quasi-steady-state conditions (>10 s). An extensive set of injector diagnostics permits evaluation of parameters for each pellet shot, including speed, mass, and integrity. Pellet speeds can be varied but typically range from 1.0 to 1.5 km/s. Over 5000 pellets have been fired with the equipment at JET, including about 2000 pellets shot for plasma fueling experiments. In recent experiments, the system performance has been outstanding, including excellent reproducibility in pellet speed and mass and a reliability of >98% in delivery of pellets to the plasma. 7 refs., 5 figs

  18. Improved reliability of wind turbine towers with active tuned mass dampers (ATMDs)

    Science.gov (United States)

    Fitzgerald, Breiffni; Sarkar, Saptarshi; Staino, Andrea

    2018-04-01

    Modern multi-megawatt wind turbines are composed of slender, flexible, and lightly damped blades and towers. These components exhibit high susceptibility to wind-induced vibrations. As the size, flexibility and cost of the towers have increased in recent years, the need to protect these structures against damage induced by turbulent aerodynamic loading has become apparent. This paper combines structural dynamic models and probabilistic assessment tools to demonstrate improvements in structural reliability when modern wind turbine towers are equipped with active tuned mass dampers (ATMDs). This study proposes a multi-modal wind turbine model for wind turbine control design and analysis. This study incorporates an ATMD into the tower of this model. The model is subjected to stochastically generated wind loads of varying speeds to develop wind-induced probabilistic demand models for towers of modern multi-megawatt wind turbines under structural uncertainty. Numerical simulations have been carried out to ascertain the effectiveness of the active control system to improve the structural performance of the wind turbine and its reliability. The study constructs fragility curves, which illustrate reductions in the vulnerability of towers to wind loading owing to the inclusion of the damper. Results show that the active controller is successful in increasing the reliability of the tower responses. According to the analysis carried out in this paper, a strong reduction of the probability of exceeding a given displacement at the rated wind speed has been observed.

  19. Reliability of infarct volumetry: Its relevance and the improvement by a software-assisted approach.

    Science.gov (United States)

    Friedländer, Felix; Bohmann, Ferdinand; Brunkhorst, Max; Chae, Ju-Hee; Devraj, Kavi; Köhler, Yvette; Kraft, Peter; Kuhn, Hannah; Lucaciu, Alexandra; Luger, Sebastian; Pfeilschifter, Waltraud; Sadler, Rebecca; Liesz, Arthur; Scholtyschik, Karolina; Stolz, Leonie; Vutukuri, Rajkumar; Brunkhorst, Robert

    2017-08-01

    Despite the efficacy of neuroprotective approaches in animal models of stroke, their translation has so far failed from bench to bedside. One reason is presumed to be a low quality of preclinical study design, leading to bias and a low a priori power. In this study, we propose that the key read-out of experimental stroke studies, the volume of the ischemic damage as commonly measured by free-handed planimetry of TTC-stained brain sections, is subject to an unrecognized low inter-rater and test-retest reliability with strong implications for statistical power and bias. As an alternative approach, we suggest a simple, open-source, software-assisted method, taking advantage of automatic-thresholding techniques. The validity and the improvement of reliability by an automated method to tMCAO infarct volumetry are demonstrated. In addition, we show the probable consequences of increased reliability for precision, p-values, effect inflation, and power calculation, exemplified by a systematic analysis of experimental stroke studies published in the year 2015. Our study reveals an underappreciated quality problem in translational stroke research and suggests that software-assisted infarct volumetry might help to improve reproducibility and therefore the robustness of bench to bedside translation.

  20. Reliability calculations

    International Nuclear Information System (INIS)

    Petersen, K.E.

    1986-03-01

    Risk and reliability analysis is increasingly being used in evaluations of plant safety and plant reliability. The analysis can be performed either during the design process or during the operation time, with the purpose to improve the safety or the reliability. Due to plant complexity and safety and availability requirements, sophisticated tools, which are flexible and efficient, are needed. Such tools have been developed in the last 20 years and they have to be continuously refined to meet the growing requirements. Two different areas of application were analysed. In structural reliability probabilistic approaches have been introduced in some cases for the calculation of the reliability of structures or components. A new computer program has been developed based upon numerical integration in several variables. In systems reliability Monte Carlo simulation programs are used especially in analysis of very complex systems. In order to increase the applicability of the programs variance reduction techniques can be applied to speed up the calculation process. Variance reduction techniques have been studied and procedures for implementation of importance sampling are suggested. (author)

  1. Reliability and Maintainability Model (RAM): User and Maintenance Manual. Part 2; Improved Supportability Analysis

    Science.gov (United States)

    Ebeling, Charles E.

    1996-01-01

    This report documents the procedures for utilizing and maintaining the Reliability & Maintainability Model (RAM) developed by the University of Dayton for the National Aeronautics and Space Administration (NASA) Langley Research Center (LaRC). The purpose of the grant is to provide support to NASA in establishing operational and support parameters and costs of proposed space systems. As part of this research objective, the model described here was developed. This Manual updates and supersedes the 1995 RAM User and Maintenance Manual. Changes and enhancements from the 1995 version of the model are primarily a result of the addition of more recent aircraft and shuttle R&M data.

  2. Substation design improvement with a probabilistic reliability approach using the TOPASE program

    Energy Technology Data Exchange (ETDEWEB)

    Bulot, M.; Heroin, G.; Bergerot, J-L.; Le Du, M. [Electricite de France (France)

    1997-12-31

    TOPASE, (the French acronym for Probabilistic Tools and Data Processing for the Analysis of Electric Systems), developed by Electricite de France (EDF) to perform reliability studies on transmission substations, was described. TOPASE serves a dual objective of assisting in the automation of HV substation studies, as well as enabling electrical systems experts who are not necessarily specialists in reliability studies to perform such studies. The program is capable of quantifying the occurrence rate of undesirable events and of identifying critical equipment and the main incident scenarios. The program can be used to improve an existing substation, to choose an HV structure during the design stage, or to choose a system of protective devices. Data collected during 1996 and 1997 will be analyzed to identify useful experiences and to validate the basic concepts of the program. 4 figs.

  3. ERP application of real-time vdc-enabled last planner system for planning reliability improvement

    DEFF Research Database (Denmark)

    Cho, S.; Sørensen, Kristian Birch; Fischer, M.

    2009-01-01

    The Last Planner System (LPS) has since its introduction in 1994 become a widely used method of AEC practitioners for improvement of planning reliability and tracking and monitoring of project progress. However, the observations presented in this paper indicate that the last planners...... and coordinators are in need of a new system that integrates the existing LPS with Virtual Design and Construction (VDC), Enterprise Resource Planning (ERP) systems, and automatic object identification by means of Radio Frequency Identification (RFID) technology. This is because current practice of the LPS...... implementations is guesswork-driven, textual report-generated, hand-updated, and even interpersonal trust-oriented, resulting in less accurate and reliable plans. This research introduces a prototype development of the VREL (VDC + RFID + ERP + LPS) integration to generate a real-time updated cost + physical...

  4. STUDIES ON IGBT MODULE TO IMPROVE THE RELIABILITY OF POWER ELECTRONIC SYSTEMS

    DEFF Research Database (Denmark)

    Choi, Uimin

    component level to converter level. It is divided into two main parts: the first part, which consists of Chapters 2 and 3, is reliability studies of the IGBT module regarding thermal stresses and the second part, composed of Chapters 4 and 5, discusses strategies to improve the reliability and availability...... are presented. Then, in Chapter 3, the effect of junction temperature swing duration t△Tj on the lifetime of the transfer molded Intelligent Power IGBT Module is investigated and modeled based on the power cycling test results. In addition, the physics-of-failure analysis results of the tested modules...... are presented. Finally, in Chapters 4 and 5, open-circuit fault detection and fault-tolerant control methods are proposed for two kinds of neutral-point clamped three-level inverters T-type and NPC inverters. One of main contributions in this project is the development of an apparatus and methodology...

  5. Prediction method of long-term reliability in improving residual stresses by means of surface finishing

    International Nuclear Information System (INIS)

    Sera, Takehiko; Hirano, Shinro; Chigusa, Naoki; Okano, Shigetaka; Saida, Kazuyoshi; Mochizuki, Masahito; Nishimoto, Kazutoshi

    2012-01-01

    Surface finishing methods, such as Water Jet Peening (WJP), have been applied to welds in some major components of nuclear power plants as a counter measure to Primary Water Stress Corrosion Cracking (PWSCC). In addition, the methods of surface finishing (buffing treatment) is being standardized, and thus the buffing treatment has been also recognized as the well-established method of improving stress. On the other hand, the long-term stability of peening techniques has been confirmed by accelerated test. However, the effectiveness of stress improvement by surface treatment is limited to thin layers and the effect of complicated residual stress distribution in the weld metal beneath the surface is not strictly taken into account for long-term stability. This paper, therefore, describes the accelerated tests, which confirmed that the long-term stability of the layer subjected to buffing treatment was equal to that subjected to WJP. The long-term reliability of very thin stress improved layer was also confirmed through a trial evaluation by thermal elastic-plastic creep analysis, even if the effect of complicated residual stress distribution in the weld metal was excessively taken into account. Considering the above findings, an approach is proposed for constructing the prediction method of the long-term reliability of stress improvement by surface finishing. (author)

  6. Improving operation notes to meet British Orthopaedic Association guidelines.

    Science.gov (United States)

    Morgan, David; Fisher, Noel; Ahmad, Aman; Alam, Fazle

    2009-04-01

    Operation notes are an important part of medical records for clinical, academic and medicolegal reasons. This study audited the quality of operative note keeping for total knee replacements against the standards set by the British Orthopaedic Association (BOA). A prospective review of all patients undergoing total knee replacement at a district general hospital over 8 months. Data recorded were compared with those required by the BOA good-practice guidelines. Change in practice was implemented and the audit cycle completed. Data were statistically analysed. A total of 129 operation notes were reviewed. There was a significant improvement in the mean number of data points recorded from 9.6 to 13.1. The least well recorded data were diagnosis, description of findings, alignment and postoperative flexion range. All had a significant improvement except description of findings. The operating surgeon writing the note improved from 56% to 67%. Detailed postoperative instructions also improved in quality. Surgeon education and the use of a checklist produce better quality total knee replacement operation notes in line with BOA guidelines. Further improvements may be made by making the data points part of the operation note itself.

  7. Model case IRS-RWE for the determination of reliability data in practical operation

    Energy Technology Data Exchange (ETDEWEB)

    Hoemke, P; Krause, H

    1975-11-01

    Reliability und availability analyses are carried out to assess the safety of nuclear power plants. The paper deals in the first part with the requirement of accuracy for the input data of such analyses and in the second part with the prototype data collection of reliability data 'Model case IRS-RWE'. The objectives and the structure of the data collection are described. The present results show that the estimation of reliability data in power plants is possible and gives reasonable results.

  8. The Effects of International Operations on the Relationship Between Manufacturing Improvement Programs and Operational Performance

    DEFF Research Database (Denmark)

    Matyusz, Zsolt; Demeter, Krisztina; Boer, Harry

    The link between manufacturing programs and operational performance, and the effects of company internal and external factors on that relationship, are well studied in the literature, both theoretically and empirically. However, previous studies rarely took into account how the scope of operations...... of the business unit affects the relationship between manufacturing programs and performances. We investigate the scope of operations from the manufacturing perspective (i.e. companies that manufacture in only one country have narrow scope of operations, while companies that manufacture in more than one country...... have broad scope of operations). We apply structural equation modelling (SEM) using PLS path modelling to investigate the effect of scope of operations on the relationship between manufacturing improvement programs and operational performance. Manufacturing improvement programs are programs like...

  9. High-power and highly reliable 638-nm band BA-LD for CW operation

    Science.gov (United States)

    Nishida, Takehiro; Kuramoto, Kyosuke; Abe, Shinji; Kusunoki, Masatsugu; Miyashita, Motoharu; Yagi, Tetsuya

    2018-02-01

    High-power laser diodes (LDs) are strongly demanded as light sources of display applications. In multiple spatial light modulator-type projectors or liquid crystal displays, the light source LDs are operated under CW condition. The high-power 638-nm band broad-area LD for CW operation was newly developed. The LD consisted of two stripes with each width of 75 μm to reduce both an optical power density at a front facet and a threshold current. The newly improved epitaxial technology was also applied to the LD to suppress an electron overflow from an active layer. The LD showed superior output characteristics, such as output of 1.77 W at case temperature of 55 °C with wall plug efficiency (WPE) of 23%, which was improved by 40% compared with the current product. The peak WPE at 25 °C reached 40.6% under the output power of 2.37 W, CW, world highest.

  10. Evaluation and improvement in nondestructive examination (NDE) reliability for in-service inspection of light water reactors

    International Nuclear Information System (INIS)

    Deffenbaugh, J.D.; Good, M.S.; Green, E.R.; Heasler, P.G.; Simonen, F.A.; Spanner, J.C.; Taylor, T.T.

    1988-01-01

    The evaluation and improvement of NDE Reliability for In-service Inspection (ISI) of Light Water Reactors (NDE Reliability) Program at Pacific Northwest Laboratory (PNL) was established to determine the reliability of current ISI techniques and to develop recommendations that will ensure a suitably high inspection reliability. The objectives of this NRC program are to: determine the reliability of ultrasonic ISI performed on commercial light-water reactor (LWR) primary systems; determine the impact of NDE unreliability on system safety and determine the level of inspection reliability required to ensure a suitably low failure probability using probabilistic fracture mechanics analysis; evaluate the degree of reliability improvement that could be achieved using improved and advanced NDE technique; and recommend revisions to ASME Code, Section XI, and Regulatory Requirements, based on material properties, service conditions, and NDE uncertainties, that will ensure suitably low failure probabilities. The program consists of three basic tasks: a Piping task, a Pressure Vessel task, and an Evaluation and Improvement in NDE Reliability task. The major efforts were concentrated in the Piping task and the Evaluation and Improvement in NDE Reliability task

  11. Human performance in an operational event - how to improve it? An initiative in a French NPP

    International Nuclear Information System (INIS)

    Meslin, M.

    1998-01-01

    In the case of the Saint-Laurent-des-Eaux French nuclear power station, the author comments the elements and principles of human factor policy which have been implemented, the organizational implications of this implementation (building up of an internal human factors network), and briefly evokes studies and initiatives aimed at improving the quality of operation from a general point of view and through projects aiming at analyzing and at a valorisation of human reliability in activities dealing with reactor operation. He also comments the perception and appropriation of quality in the different departments

  12. Improving Reliability of High Power Quasi-CW Laser Diode Arrays for Pumping Solid State Lasers

    Science.gov (United States)

    Amzajerdian, Farzin; Meadows, Byron L.; Baker, Nathaniel R.; Barnes, Bruce W.; Baggott, Renee S.; Lockard, George E.; Singh, Upendra N.; Kavaya, Michael J.

    2005-01-01

    Most Lidar applications rely on moderate to high power solid state lasers to generate the required transmitted pulses. However, the reliability of solid state lasers, which can operate autonomously over long periods, is constrained by their laser diode pump arrays. Thermal cycling of the active regions is considered the primary reason for rapid degradation of the quasi-CW high power laser diode arrays, and the excessive temperature rise is the leading suspect in premature failure. The thermal issues of laser diode arrays are even more drastic for 2-micron solid state lasers which require considerably longer pump pulses compared to the more commonly used pump arrays for 1-micron lasers. This paper describes several advanced packaging techniques being employed for more efficient heat removal from the active regions of the laser diode bars. Experimental results for several high power laser diode array devices will be reported and their performance when operated at long pulsewidths of about 1msec will be described.

  13. Improved Iterative Hard- and Soft-Reliability Based Majority-Logic Decoding Algorithms for Non-Binary Low-Density Parity-Check Codes

    Science.gov (United States)

    Xiong, Chenrong; Yan, Zhiyuan

    2014-10-01

    Non-binary low-density parity-check (LDPC) codes have some advantages over their binary counterparts, but unfortunately their decoding complexity is a significant challenge. The iterative hard- and soft-reliability based majority-logic decoding algorithms are attractive for non-binary LDPC codes, since they involve only finite field additions and multiplications as well as integer operations and hence have significantly lower complexity than other algorithms. In this paper, we propose two improvements to the majority-logic decoding algorithms. Instead of the accumulation of reliability information in the existing majority-logic decoding algorithms, our first improvement is a new reliability information update. The new update not only results in better error performance and fewer iterations on average, but also further reduces computational complexity. Since existing majority-logic decoding algorithms tend to have a high error floor for codes whose parity check matrices have low column weights, our second improvement is a re-selection scheme, which leads to much lower error floors, at the expense of more finite field operations and integer operations, by identifying periodic points, re-selecting intermediate hard decisions, and changing reliability information.

  14. Using operational data to estimate the reliable yields of water-supply wells

    Science.gov (United States)

    Misstear, Bruce D. R.; Beeson, Sarah

    The reliable yield of a water-supply well depends on many different factors, including the properties of the well and the aquifer; the capacities of the pumps, raw-water mains, and treatment works; the interference effects from other wells; and the constraints imposed by ion licences, water quality, and environmental issues. A relatively simple methodology for estimating reliable yields has been developed that takes into account all of these factors. The methodology is based mainly on an analysis of water-level and source-output data, where such data are available. Good operational data are especially important when dealing with wells in shallow, unconfined, fissure-flow aquifers, where actual well performance may vary considerably from that predicted using a more analytical approach. Key issues in the yield-assessment process are the identification of a deepest advisable pumping water level, and the collection of the appropriate well, aquifer, and operational data. Although developed for water-supply operators in the United Kingdom, this approach to estimating the reliable yields of water-supply wells using operational data should be applicable to a wide range of hydrogeological conditions elsewhere. Résumé La productivité d'un puits capté pour l'adduction d'eau potable dépend de différents facteurs, parmi lesquels les propriétés du puits et de l'aquifère, la puissance des pompes, le traitement des eaux brutes, les effets d'interférences avec d'autres puits et les contraintes imposées par les autorisations d'exploitation, par la qualité des eaux et par les conditions environnementales. Une méthodologie relativement simple d'estimation de la productivité qui prenne en compte tous ces facteurs a été mise au point. Cette méthodologie est basée surtout sur une analyse des données concernant le niveau piézométrique et le débit de prélèvement, quand ces données sont disponibles. De bonnes données opérationnelles sont particuli

  15. Improvement of Matrix Converter Drive Reliability by Online Fault Detection and a Fault-Tolerant Switching Strategy

    DEFF Research Database (Denmark)

    Nguyen-Duy, Khiem; Liu, Tian-Hua; Chen, Der-Fa

    2011-01-01

    The matrix converter system is becoming a very promising candidate to replace the conventional two-stage ac/dc/ac converter, but system reliability remains an open issue. The most common reliability problem is that a bidirectional switch has an open-switch fault during operation. In this paper, a...

  16. AREVA's toolbox for long-term best performance and reliable operation of nuclear steam generators

    International Nuclear Information System (INIS)

    Drexler, Andreas; Weiss, Steffen; Caris, Neil; Stiepani, Christoph

    2015-01-01

    Long-term integrity and high performance of major plant systems and components are of uppermost importance for the successful operation of any power plant. AREVA's experience gathered with water-steam cycle chemistry treatments in more than 40 years yields the conclusion: Accumulation of corrosion products in SGs may result in local overheating and enrichment of impurities up to critical levels. This can lead to several degradation phenomena of the structural materials of the SGs. Therefore, minimization of corrosion product generation and prevention of deposit accumulation is required. The objective of AREVA's asset management program is to support operators by minimizing corrosion damage and performance losses of water-steam cycle systems and components and thereby to maximize the availability and economic performance of the plant. Such asset management program is in principle a closed cycle process. It is based on control, corrective and preventive measures. The objective of control measure is deriving a widespread assessment of the corrosion status of the steam-water cycle which yields to weak points and identifying the best suited corrective and/or preventive measures. In the subsequent steps appropriate measures which improve the current status or counteract on identified issues are identified and applied. Corrective measures, likes mechanical and/or chemical cleaning are targeting the minimization of negative influence on plant performance caused by corrosion in the steam-water cycle. Complementary to corrective measures are preventive ones, like optimization of pH strategy and AREVA's FFA technology could by applied. They are focusing on the origin of corrosion product generation. AREVA is offering a toolbox for long-term best performance and reliable operation of NPPs. (author)

  17. Nuclear power generating station operability assurance reliability, availability, and maintainability application for maintenance management

    International Nuclear Information System (INIS)

    Cleveland, J.W.; Regenie, T.R.; Wilson, R.J.

    1985-01-01

    Environmental qualification and equipment warrantee insurance stipulations should be supplemented with a reliable maintainability program structured to identify and control fast failing subcomponents within critical equipment. Anticipation of equipment subcomponent failures can control unnecessary plant off-line occurrences. Incorporation of reliability, availability, and maintainability considerations into plant maintenance policies on power generation and safety related items have positive cost benefit advantages

  18. An improved control system for a remotely operated vessel

    Science.gov (United States)

    Bachnak, Rafic; Mendez, Marc; Esparza, Jack; Fahed, Oliver

    2006-05-01

    Collecting environmental data in coastal bays presents several challenges to the scientist. One of the most pressing issues is how to efficiently and reliably gather data in shallow water areas-environments that often preclude the use of traditional boats. Obstacles that are encountered in such environments include difficulty in covering large territories and the presence of inaccessible areas due to a variety of reasons, such as soft bottoms or contamination. There is also a high probability of disturbing the test area while placing the sensors. This paper outlines the development of a remotely operated boat and its real-time control system.

  19. Reliability through markets in Ontario : submission by the Independent Electricity Market Operator to the Minister of Energy's Consultation Process

    International Nuclear Information System (INIS)

    2003-01-01

    For the past five years, Ontario has invested $1 billion to restructure and open its electricity market to competition. In recent months, and in response to residential consumers pricing concerns, the Independent Electricity Market Operator (IMO) transferred credits to local distribution companies allowing them to issue $75 rebates to all affected customers as of December 1, 2002, and to bill low-volume and other designated customers at a rate of 4.3 cents per kilowatt hour for the commodity portion of their bills. This report addresses the concern that price responsiveness will be lost for those parts of the market with fixed prices. It was noted that the reliability of the power system could be placed at risk if the range of customers with fixed prices is broadened. Fixed prices would also jeopardize the province's ability to attract new supply and enhance competition in the electricity sector. The IMO believes that price responsiveness in the wholesale market is crucial to the reliability of the electricity system and recommends that a plan for any additional fixed pricing should include a clearly defined phase-out over the period ending in 2006 as new supply comes on-line. The IMO emphasizes that the lack of price responsiveness to the market, particularly in peak energy demand periods, is equivalent to adding hundreds of MW to the load. The report presents lessons learned in other jurisdictions and highlights noteworthy considerations such as the market power mitigation agreement, improving competition, a phased-in approach, and demand side initiatives

  20. Lessons learned from operating experience can improve future light water reactor design

    International Nuclear Information System (INIS)

    Basso, G.

    1983-01-01

    The abundant and detailed documentation already existing in the field of operating experience of U.S.A. nuclear plants allows us to evaluate on a statistical basis the real reliability and availability of specific classes of components and systems. However the multiple connections of mechanical, electrical, electronic, chemical, structural components, which interact each other in many different modes and constitute indeed a single functional complex, make the casual linkage of failures and abnormal occurrences to individual components in some extent arbitrary. In fact many failures and abnormal occurrences originate from generic problems and design deficiencies which do not pertain to the effected components. As a consequence of this, the verification of component reliability may be considered a preliminary step in the process of assessing the safety level of a nuclear plant or improving its operating availability. Further analysis of afilure data in the context of the overall interconnected plant are required for bringing to light the real, remote causes

  1. Improvement in the reliability of shells for light water reactors by manufacturing from hollow ingots

    International Nuclear Information System (INIS)

    Bocquet, P.; Blondeau, R.; Poitrault, I.; Badeau, J.P.; Dumont, R.

    1989-01-01

    The example of forging shells for PWR type reactors is proposed to show how the choice of the manufacturing process may be of prime importance for the component integrity by the reduction of the detrimental effects of segregations. The forging shells (20MnMoNi55) manufactured from hollow ingot are free of any segregation in the critical area located just at the internal surface and sub-surface. Manufacturing problems associated to these segregations in shells issued from conventional ingots, in particular welding difficulties for cladding, have been reduced or eleminated. The reliability of these components present an improved resistance to irradiation embrittlement. (DG)

  2. A review of manufacturing metrology for improved reliability of silicon photovoltaic modules

    Science.gov (United States)

    Davis, Kristopher O.; Walters, Joseph; Schneller, Eric; Seigneur, Hubert; Brooker, R. Paul; Scardera, Giuseppe; Rodgers, Marianne P.; Mohajeri, Nahid; Shiradkar, Narendra; Dhere, Neelkanth G.; Wohlgemuth, John; Rudack, Andrew C.; Schoenfeld, Winston V.

    2014-10-01

    In this work, the use of manufacturing metrology across the supply chain to improve crystalline silicon (c-Si) photovoltaic (PV) module reliability and durability is addressed. Additionally, an overview and summary of a recent extensive literature survey of relevant measurement techniques aimed at reducing or eliminating the probability of field failures is presented. An assessment of potential gaps is also given, wherein the PV community could benefit from new research and demonstration efforts. This review is divided into three primary areas representing different parts of the c-Si PV supply chain: (1) feedstock production, crystallization and wafering; (2) cell manufacturing; and (3) module manufacturing.

  3. Improving the reliability of peer-reviewed publications: We are all in it together

    Directory of Open Access Journals (Sweden)

    Stephen A. Bustin

    2016-03-01

    Full Text Available The current, and welcome, focus on standardization of techniques and transparency of reporting in the biomedical, peer-reviewed literature is commendable. However, that focus has been intermittent as well as lacklustre and so failed to tackle the alarming lack of reliability and reproducibly of biomedical research. Authors have access to numerous recommendations, ranging from simple standards dealing with technical issues to those regulating clinical trials, suggesting that improved reporting guidelines are not the solution. The elemental solution is for editors to require meticulous implementation of their journals’ instructions for authors and reviewers and stipulate that no paper is published without a transparent, complete and accurate materials and methods section.

  4. Improving the reliability of GUB-20000 gamma unit for large laboratory animals irradiation

    International Nuclear Information System (INIS)

    Videnskij, V.G.

    1994-01-01

    GUB-20000 gamma unit for large laboratory animals irradiation is described and results of investigation into its reliability improvement are considered. Cables of superstrength high-modular (SSHM) polymer fibre and capron fiber were tested to establish their applicability in the above unit. Samples were exposed to gamma-radiation and fast electrons and were tested for tensile properties. Application of SSHM-fiber cables to modernize the GUB-20000 unit was found to be perspective due to superhigh radiation strength. 5 refs., 1 tab

  5. Improved structural integrity through advances in reliable residual stress measurement: the impact of ENGIN-X

    Science.gov (United States)

    Edwards, L.; Santisteban, J. R.

    The determination of accurate reliable residual stresses is critical to many fields of structural integrity. Neutron stress measurement is a non-destructive technique that uniquely provides insights into stress fields deep within engineering components and structures. As such, it has become an increasingly important tool within engineering, leading to improved manufacturing processes to reduce stress and distortion as well as to the definition of more precise lifing procedures. This paper describes the likely impact of the next generation of dedicated engineering stress diffractometers currently being constructed and the utility of the technique using examples of residual stresses both beneficial and detrimental to structural integrity.

  6. Mining protein interactomes to improve their reliability and support the advancement of network medicine

    KAUST Repository

    Alanis Lobato, Gregorio

    2015-09-23

    High-throughput detection of protein interactions has had a major impact in our understanding of the intricate molecular machinery underlying the living cell, and has permitted the construction of very large protein interactomes. The protein networks that are currently available are incomplete and a significant percentage of their interactions are false positives. Fortunately, the structural properties observed in good quality social or technological networks are also present in biological systems. This has encouraged the development of tools, to improve the reliability of protein networks and predict new interactions based merely on the topological characteristics of their components. Since diseases are rarely caused by the malfunction of a single protein, having a more complete and reliable interactome is crucial in order to identify groups of inter-related proteins involved in disease etiology. These system components can then be targeted with minimal collateral damage. In this article, an important number of network mining tools is reviewed, together with resources from which reliable protein interactomes can be constructed. In addition to the review, a few representative examples of how molecular and clinical data can be integrated to deepen our understanding of pathogenesis are discussed.

  7. An improved IEEE 802.11 protocol for reliable data transmission in power distribution fault diagnosis

    Energy Technology Data Exchange (ETDEWEB)

    Campoccia, F.; Di Silvestre, M.L.; Sanseverino, E.R.; Zizzo, G. [Palermo Univ., Palermo (Italy)

    2010-10-15

    In power systems, on-line transmission between local units and the central unit can be done by means of power line communications or wireless technology. During an electrical fault, the reliability of the distribution system depends on the security of the timely protective and restorative actions on the network. This paper focused on the WiFi system because of its economy and ease of installation. However, WiFi systems are typically managed by the IEEE 802.11 protocol, which is not reliable in terms of security in data communication. In WiFi networks, data is divided into packets and sent in succession to reduce errors within the radio channel. The IEEE 802.11 protocol has high probability for loss of packets or delay in their transmission. In order to ensure the reliability of data transmission times between two terminal units connected by WiFi stations, a new protocol was derived by modifying the IEEE 802.11. The improvements of the new protocol were highlighted and its capability for the diagnostic service was verified. The modified protocol eliminates the danger of collisions between packets and optimizes the transmission time for sending information. 6 refs., 7 tabs., 8 figs.

  8. Bootstrap analysis of designed experiments for reliability improvement with a non-constant scale parameter

    International Nuclear Information System (INIS)

    Wang, Guodong; He, Zhen; Xue, Li; Cui, Qingan; Lv, Shanshan; Zhou, Panpan

    2017-01-01

    Factors which significantly affect product reliability are of great interest to reliability practitioners. This paper proposes a bootstrap-based methodology for identifying significant factors when both location and scale parameters of the smallest extreme value distribution vary over experimental factors. An industrial thermostat experiment is presented, analyzed, and discussed as an illustrative example. The analysis results show that 1) the misspecification of a constant scale parameter may lead to misidentify spurious effects; 2) the important factors identified by different bootstrap methods (i.e., percentile bootstrapping, bias-corrected percentile bootstrapping, and bias-corrected and accelerated percentile bootstrapping) are different; 3) the number of factors affecting 10th percentile lifetime significantly is less than the number of important factors identified at 63.21th percentile. - Highlights: • Product reliability is improved by design of experiments under both scale and location parameters of smallest extreme value distribution vary with experimental factors. • A bootstrap-based methodology is proposed to identify important factors which affect 100pth lifetime percentile significantly. • Bootstrapping confidence intervals associating experimental factors are obtained by using three bootstrap methods (i.e., percentile bootstrapping, bias-corrected percentile bootstrapping, and bias-corrected and accelerated percentile bootstrapping). • The important factors identified by different bootstrap methods are different. • The number of factors affecting 10th percentile significantly is less than the number of important factors identified at 63.21th percentile.

  9. Mining protein interactomes to improve their reliability and support the advancement of network medicine

    Directory of Open Access Journals (Sweden)

    Gregorio eAlanis-Lobato

    2015-09-01

    Full Text Available High-throughput detection of protein interactions has had a major impact in our understanding of the intricate molecular machinery underlying the living cell, and has permitted the construction of very large protein interactomes. The protein networks that are currently available are incomplete and a significant percentage of their interactions are false positives. Fortunately, the structural properties observed in good quality social or technological networks are also present in biological systems. This has encouraged the development of tools, to improve the reliability of protein networks and predict new interactions based merely on the topological characteristics of their components. Since diseases are rarely caused by the malfunction of a single protein, having a more complete and reliable interactome is crucial in order to identify groups of inter-related proteins involved in disease aetiology. These system components can then be targeted with minimal collateral damage. In this article, an important number of network mining tools is reviewed, together with resources from which reliable protein interactomes can be constructed. In addition to the review, a few representative examples of how molecular and clinical data can be integrated to deepen our understanding of pathogenesis are discussed.

  10. Coal quality influence on availability and reliability of two 620 MW lignite fired units after 100 000 operating hours

    International Nuclear Information System (INIS)

    Markovic, Dragomir

    1997-01-01

    General statistics data on operation of two 620 MW low calorific value coal fired units are foundation for analysis of influence of variable coal characteristics on availability and reliability. Changeable mineralogical structure, ash contents and heating value cause the following problems: increased abrasive wear and unstable firing. Almost 23 % of plant shutting down are caused by the mentioned reasons, which have multiplied in the last years. Analysis will show how it is possible to plan terms of overhaul of boilers with respect to quality of used coal and reliability of pipe system and maintenance of high level of availability and reliability in spite of periodical low heating value of coal. Described experiences are also important for planning, design, construction and operation of new power plants firing with same coal. (Author)

  11. Balancing low cost with reliable operation in the rotordynamic design of the ALS Liquid Hydrogen Fuel Turbopump

    Science.gov (United States)

    Greenhill, L. M.

    1990-01-01

    The Air Force/NASA Advanced Launch System (ALS) Liquid Hydrogen Fuel Turbopump (FTP) has primary design goals of low cost and high reliability, with performance and weight having less importance. This approach is atypical compared with other rocket engine turbopump design efforts, such as on the Space Shuttle Main Engine (SSME), which emphasized high performance and low weight. Similar to the SSME turbopumps, the ALS FTP operates supercritically, which implies that stability and bearing loads strongly influence the design. In addition, the use of low cost/high reliability features in the ALS FTP such as hydrostatic bearings, relaxed seal clearances, and unshrouded turbine blades also have a negative influence on rotordynamics. This paper discusses the analysis conducted to achieve a balance between low cost and acceptable rotordynamic behavior, to ensure that the ALS FTP will operate reliably without subsynchronous instabilities or excessive bearing loads.

  12. Evaluation of the Influence of the Logistic Operations Reliability on the Total Costs of a Supply Chain

    Directory of Open Access Journals (Sweden)

    Lukinskiy Valery

    2016-12-01

    Full Text Available Nowadays in logistics integral processes between the material and related flows in supply chains are getting developed more and more. However, in spite of increasing volume of statistical data which reflect the integral processes, the influence evaluation issues of the logistic operations reliability indexes on the total logistics costs remain open and require the corresponding researches implementation.

  13. THE SIMULATION DIAGNOSTIC METHODS AND REGENERATION WAYS OF REINFORCED - CONCRETE CONSTRUCTIONS OF BRIDGES IN PROVIDING THEIR OPERATING RELIABILITY AND LONGEVITY

    Directory of Open Access Journals (Sweden)

    B. V. Savchinskiy

    2010-03-01

    Full Text Available On the basis of analysis of existing diagnostic methods and regeneration ways of reinforced-concrete constructions of bridges the recommendations on introduction of new modern technologies of renewal of reinforced-concrete constructions of bridges in providing their operating reliability and longevity are offered.

  14. THE SIMULATION DIAGNOSTIC METHODS AND REGENERATION WAYS OF REINFORCED - CONCRETE CONSTRUCTIONS OF BRIDGES IN PROVIDING THEIR OPERATING RELIABILITY AND LONGEVITY

    OpenAIRE

    B. V. Savchinskiy

    2010-01-01

    On the basis of analysis of existing diagnostic methods and regeneration ways of reinforced-concrete constructions of bridges the recommendations on introduction of new modern technologies of renewal of reinforced-concrete constructions of bridges in providing their operating reliability and longevity are offered.

  15. 76 FR 66328 - Callaway Golf Ball Operations, Inc., Including On-Site Leased Workers From Reliable Temp Services...

    Science.gov (United States)

    2011-10-26

    ... DEPARTMENT OF LABOR Employment and Training Administration [TA-W-80,110] Callaway Golf Ball... Golf Ball Operations, Inc., including on-site leased workers from Reliable Temp Services, Inc., and... production of golf balls. The notice was published in the Federal Register on July 8, 2011 (76 FR 40401). At...

  16. Introduction of composite reliability evaluation in power system operation planning; Introducao da confiabilidade composta no planejamento da operacao eletrica

    Energy Technology Data Exchange (ETDEWEB)

    Mello, J C.O. [Centro de Pesquisas de Energia Eletrica (CEPEL), Rio de Janeiro, RJ (Brazil); Schilling, M T; Gomes, P [ELETROBRAS, Rio de Janeiro, RJ (Brazil)

    1994-12-31

    This paper gives an overview of an ongoing, detailed and first-hand investigation about the current reliability levels of the Brazilian power system, as seen from the electrical operation planning point-of-view. A set of practical results are presented and commented. (author) 41 refs., 4 figs., 4 tabs.

  17. New software for improving performance in wind farm operations

    Energy Technology Data Exchange (ETDEWEB)

    Collins, Mark [Ekho for Wind (Canada)

    2011-07-01

    The performance of wind farms depends on multiple field and business systems. This makes operational planning difficult because of so many data being in separate systems, duplication of data and the impossibility of gathering all relevant data together in one place. The aim of this paper is to present a new software, Ekho for Wind, which helps improve performance in wind farm operations by providing features such as high level views, performance analysis, downtime tracking, quality data management and forecast generation. This new software provides operational intelligence which offers incentives for continuous improvement. Ekho for Wind can bring such benefits as maximization of generation, increased lifetime of assets, minimization of costs and increased profitability. This presentation introduced a new software for improving the performance of wind farms and the lifetime of assets, resulting in significant payback.

  18. Issues to improve the safety of 18K370 steam turbine operation

    Directory of Open Access Journals (Sweden)

    Bzymek Grzegorz

    2017-01-01

    Full Text Available The paper presents the process of improving the safety and reliability of operation the 18K370 steam turbines Opole Power Plant since the first failure in 2010 [1], up to install the on-line monitoring system [2]. It shows how the units work and how to analyse the contol stage as a critical node in designing the turbine. Selected results of the analysis of the strength of CSD (Computational Solid Dynamic and the nature of the flow in different operating regimes - thanks to CFD (Computational Fluid Dynamic analysis have been included. We have also briefly discussed the way of lifecycle management of individual elements [2,3]. The presented actions could be considered satisfactory, and improve the safety of operating steam turbines of type 18K370.

  19. Improving road transport operations through lean thinking: A case study

    OpenAIRE

    Villarreal, B.; Garza-Reyes, J. A.; Kumar, V.; Lim, M. K.

    2017-01-01

    Traditionally, logistics and transportation problems have been addressed through mathematical modelling, operations research, and simulation methods. This paper documents a case study where the road transport operations of a leading Mexican brewery organisation have been improved through lean thinking and waste reduction. Two lean-based principles and tools were combined; the Seven Transportation Extended Wastes (STEWs) and Transportation Value Stream Mapping (TVSM), and three systematic step...

  20. The model case IRS-RWE for the determination of reliability data in practical operation

    International Nuclear Information System (INIS)

    Hoemke, P.; Krause, H.

    1975-11-01

    Reliability und availability analyses are carried out to assess the safety of nuclear power plants. This paper deals in the first part with the requirement of accuracy for the input data of such analyses and in the second part with the prototype data collection of reliability data 'Model case IRS-RWE'. The objectives and the structure of the data collection will be described. The present results show that the estimation of reliability data in power plants is possible and gives reasonable results. (orig.) [de

  1. Improvement of nuclear power plant operation and maintenance in Japan

    International Nuclear Information System (INIS)

    Kazushige Hamazaki

    1987-01-01

    Following the inauguration of commercial nuclear power generation in Japan in 1966, capacity factors were held in the relatively low level until around 1975 due to initial-period troubles. With subsequent improvement, however, capacity factors have climbed steadily and recently been sustaining more than 70%. To obtain this successful result, a various kind of improvement have been made not only for the operation management area but also for the maintenance management area in conjunction with the successive effort to reflect the operating experiences to the early stage design. Nowadays nuclear generation has assumed increasing importance for Japan's electrical power needs, and is making a great contribution to stabilizing power supply costs. (author)

  2. Use of computer codes to improve nuclear power plant operation

    International Nuclear Information System (INIS)

    Misak, J.; Polak, V.; Filo, J.; Gatas, J.

    1985-01-01

    For safety and economic reasons, the scope for carrying out experiments on operational nuclear power plants (NPPs) is very limited and any changes in technical equipment and operating parameters or conditions have to be supported by theoretical calculations. In the Nuclear Power Plant Scientific Research Institute (NIIAEhS), computer codes are systematically used to analyse actual operating events, assess safety aspects of changes in equipment and operating conditions, optimize the conditions, preparation and analysis of NPP startup trials and review and amend operating instructions. In addition, calculation codes are gradually being introduced into power plant computer systems to perform real time processing of the parameters being measured. The paper describes a number of specific examples of the use of calculation codes for the thermohydraulic analysis of operating and accident conditions aimed at improving the operation of WWER-440 units at the Jaslovske Bohunice V-1 and V-2 nuclear power plants. These examples confirm that computer calculations are an effective way of solving operating problems and of further increasing the level of safety and economic efficiency of NPP operation. (author)

  3. Reducing variability of workforce as a tool to improve plan reliability

    DEFF Research Database (Denmark)

    Wandahl, Søren; Yicheng, S.; Zygmunt, K. J.

    Variability of flow is recognized as the greatest obstacle to production management. Since the work flow and labour flow are two dominators of work performance, it is important to manage them simultaneously. The objective of this paper is to examine whether by reducing the variance of a labour flow......, a plan reliability can be improved, therefore, three different construction labour data sets have been examined by utilizing Monte Carlo Simulation, to analyze the probability to finish simulated projects within a certain time. The research findings revealed that reducing variance in the workforce flow...... does not necessarily shorten the project length, nevertheless it increases probability to finish the tasks within a critical path duration. Additionally, it was concluded, that reducing the variance of crew allocation can improve the productivity....

  4. Evolution of Machine Reliability and Life and Economics of Operational Use

    Directory of Open Access Journals (Sweden)

    Młynarski Stanisław

    2016-12-01

    Full Text Available The article presents new assumptions for reliability and life of machines, resulting from the development of technology. The innovative approach to reliability and life design as well as warranty duration planning is presented on an example of vehicle reliability characteristics. A new algorithm is proposed for the replacement of repairable objects costs by the price of life and reliability of new unrepairable ones. For the planning of the life of innovative machines, an effective method of technical progress rate determination is proposed. In conclusion, necessary modifications of machine and vehicle use systems, resulting from technology evolution and technical progress, are indicated. Finally, recommendations and directions of indispensable research in engineering and management of technical means of production are formulated.

  5. Video training and certification program improves reliability of postischemic neurologic deficit measurement in the rat.

    Science.gov (United States)

    Taninishi, Hideki; Pearlstein, Molly; Sheng, Huaxin; Izutsu, Miwa; Chaparro, Rafael E; Goldstein, Larry B; Warner, David S

    2016-12-01

    Scoring systems are used to measure behavioral deficits in stroke research. Video-assisted training is used to standardize stroke-related neurologic deficit scoring in humans. We hypothesized that a video-assisted training and certification program can improve inter-rater reliability in assessing neurologic function after middle cerebral artery occlusion in rats. Three expert raters scored neurologic deficits in post-middle cerebral artery occlusion rats using three published systems having different complexity levels (3, 18, or 48 points). The system having the highest point estimate for the correlation between neurologic score and infarct size was selected to create a video-assisted training and certification program. Eight trainee raters completed the video-assisted training and certification program. Inter-rater agreement ( Κ: score) and agreement with expert consensus scores were measured before and after video-assisted training and certification program completion. The 48-point system correlated best with infarct size. Video-assisted training and certification improved agreement with expert consensus scores (pretraining = 65 ± 10, posttraining = 87 ± 14, 112 possible scores, P  0.4 (pretraining = 4, posttraining = 9), and number of categories with an improvement in the Κ: score from pretraining to posttraining (n = 6). Video-assisted training and certification improved trainee inter-rater reliability and agreement with expert consensus behavioral scores in rats after middle cerebral artery occlusion. Video-assisted training and certification may be useful in multilaboratory preclinical studies. © The Author(s) 2015.

  6. How we improved operations in drilling pre-salt wells

    Energy Technology Data Exchange (ETDEWEB)

    Hougaz, Augusto Borella [Petroleo Brasileiro S.A. (PETROBRAS), Rio de Janeiro, RJ (Brazil); Martins, Luiz Felipe; Bittencourt, Jessica Lima; Braz, Luciano Machado [Genesis do Brasil, Sao Paulo, SP (Brazil); Damski, Carlos [Genesis Petroleum Technology Pty Ltd. (GPT), Bentley, WA (Australia)

    2012-07-01

    The development of pre-salt wells offshore Brazil has been one of the most challenging projects in history of E and P. Facing water depths of 2000+ meters, a salt layer 2000 meters thick to reach reservoirs at 7000 meters below sea level, has to use technological and procedural techniques never used before. In those 2 years of exploration of those fields many technologies were tested and improved. This paper describes the systematic approach was taken to analyze, plan and follow-up the development of drilling operations campaign in those fields, and the case study of overall process improvement. The assumption was to apply a risk analysis tool which uses previous data to analyze the performance and plan future time. The goals of this process are continuous improvement of execution and process control for each operation. Looking into previous performance, new interventions were planned more accurately and further improvements were studied. The frequent follow up of the drilling intervention was done using the statistical base to compare the most recent results. At operational level it was possible to see if the last operation was done in the 1st, 2nd, 3rd or 4th quartile of its related statistical distribution, as well as to verify the difference within P10 and P90, which indicates the control of each operation execution process. The same process was done for some rig related operations and for the whole intervention at end of it. Close contact with the intervention progress was kept and actions taken in any major deviation from the plan. This paper describes the case study where the process control and optimization of the total time for drilling 10 wells with similar design was measured between March 2009 and May 2011. It resulted in significant improvement in the drilling process. (author)

  7. Comparison of different reliability improving investment strategies of Finnish medium-voltage distribution systems

    Energy Technology Data Exchange (ETDEWEB)

    Laagland, H.

    2012-07-01

    The electricity distribution sector in Finland is highly regulated and the return on investments in distribution networks is low. Low profits don't make the electricity distribution sector attractive to outside investors. During the second regulatory period of 2008-2011 incentives are included into the Finnish regulation model which allows higher profits for the network owners for right allocated network investments leading to lower operation and interruption costs. The goal of the thesis is to find cost-effective medium-voltage distribution system investment strategies for the Finnish power distribution companies with respect to the incentives of the second regulatory period. In this work the sectionalisation concept is further developed by deriving equations for a homogeneous electricity distribution system for the economical and reliability indices as a function of the number of sectionalisation zones. The cost-effective medium-voltage distribution system investment strategies are found by studying the technical and economic interaction of feeder automation on different network structures. Ten feeder automation schemes have been applied to six urban/rural area generic feeders and two real rural area feeders of a distribution company in western Finland. The analytical approach includes modelling of the feeders and feeder functions and calculation of the economical and reliability indices. The following investment areas are included: different electricity distribution systems, new substation, new switching station, central earth-fault current compensation, cabling and feeder automation. The value of the results of this work is that they reveal the influence that feeder automation has on the reliability and economy of different distribution structures. This created transparency enables a national and/or distribution company network investment strategy to optimise the economic benefits of investments. (orig.)

  8. New design of engineered safety features-component control system to improve performance and reliability

    International Nuclear Information System (INIS)

    Kim, S.T.; Jung, H.W.; Lee, S.J.; Cho, C.H.; Kim, D.H.; Kim, H.

    2006-01-01

    Full text: Full text: The Engineered Safety Features-Component Control System (ESF-CCS) controls the engineered safety features of a Nuclear Power Plant such as Solenoid Operated Valves (SOV), Motor Operated Valves (MOV), pumps, dampers, etc. to mitigate the effects of a Design Basis Accident (DBA) or an abnormal operation. ESF-CCS serves as an interface system between the Plant Protection System (PPS) and remote actuation devices. ESF-CCS is composed of fault tolerant Group Controllers GC, Loop Controllers (LC), ESF-CCS Test and Interface Processor (ETIP) and Cabinet Operator Module (COM) and Control Channel Gateway (CCG) etc. GCs in each division are designed to be fully independent triple configuration, which perform system level NSSS and BOP ESFAS logic (2-out-of-4 logic and l-out-of-2 logic, respectively) making it possible to test each GC individually during normal operation. In the existing configuration, the safety-related plant component control is part of the Plant Control System (PCS) non-safety system. For increased safety and reliability, this design change incorporates this part into the LCs, and is therefore designed according to the safety-critical system procedures. The test and diagnosis capabilities of ETIP and COM are reinforced. By means of an automatic periodic test for all main functions of the system, it is possible to quickly determine an abnormal status of the system, and to decrease the elapsed time for tests, thus effectively increasing availability. ESF-CCS consists of four independent divisions (A, B, C, and D) in the Advanced Power Reactor 1400 (APR1400). One prototype division is being manufactured and will be tested

  9. 75 FR 81157 - Version One Regional Reliability Standard for Transmission Operations

    Science.gov (United States)

    2010-12-27

    ... not exceed the path's system operating limits, when the transmission operator implements its real-time... return the actual power flow to within [system operating limits] such that at no time shall the power... return the transmission system to within [system operating limits] within a time certain, only a...

  10. Operational validation - current status and opportunities for improvement

    International Nuclear Information System (INIS)

    Davey, E.

    2002-01-01

    The design of nuclear plant systems and operational practices is based on the application of multiple defenses to minimize the risk of occurrence of safety and production challenges and upsets. With such an approach, the effectiveness of individual or combinations of design and operational features in preventing upset challenges should be known. A longstanding industry concern is the adverse impact errors in human performance can have on plant safety and production. To minimize the risk of error occurrence, designers and operations staff routinely employ multiple design and operational defenses. However, the effectiveness of individual or combinations of defensive features in minimizing error occurrence are generally only known in a qualitative sense. More importantly, the margins to error or upset occurrence provided by combinations of design or operational features are generally not characterized during design or operational validation. This paper provides some observations and comments on current validation practice as it relates to operational human performance concerns. The paper also discusses opportunities for future improvement in validation practice in terms of the resilience of validation results to operating changes and characterization of margins to safety or production challenge. (author)

  11. Improving Wind Turbine Drivetrain Reliability Using a Combined Experimental, Computational, and Analytical Approach

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Y.; van Dam, J.; Bergua, R.; Jove, J.; Campbell, J.

    2015-03-01

    Nontorque loads induced by the wind turbine rotor overhang weight and aerodynamic forces can greatly affect drivetrain loads and responses. If not addressed properly, these loads can result in a decrease in gearbox component life. This work uses analytical modeling, computational modeling, and experimental data to evaluate a unique drivetrain design that minimizes the effects of nontorque loads on gearbox reliability: the Pure Torque(R) drivetrain developed by Alstom. The drivetrain has a hub-support configuration that transmits nontorque loads directly into the tower rather than through the gearbox as in other design approaches. An analytical model of Alstom's Pure Torque drivetrain provides insight into the relationships among turbine component weights, aerodynamic forces, and the resulting drivetrain loads. Main shaft bending loads are orders of magnitude lower than the rated torque and are hardly affected by wind conditions and turbine operations.

  12. NPP Krsko core calculations to improve operational safety

    International Nuclear Information System (INIS)

    Ivekovic, I.; Grgic, D.; Nemec, T.

    2007-01-01

    Calculation tools and methodology used to perform independent calculations of cumulative influence of different changes related to fuel and core operation of NPP Krsko were described. Some examples of steady state and transient results are used to illustrate potential improvements to understanding and reviewing plant safety. (author)

  13. Improvement of human operator vibroprotection system in the utility machine

    Science.gov (United States)

    Korchagin, P. A.; Teterina, I. A.; Rahuba, L. F.

    2018-01-01

    The article is devoted to an urgent problem of improving efficiency of road-building utility machines in terms of improving human operator vibroprotection system by determining acceptable values of the rigidity coefficients and resistance coefficients of operator’s cab suspension system elements and those of operator’s seat. Negative effects of vibration result in labour productivity decrease and occupational diseases. Besides, structure vibrations have a damaging impact on the machine units and mechanisms, which leads to reducing an overall service life of the machine. Results of experimental and theoretical research of operator vibroprotection system in the road-building utility machine are presented. An algorithm for the program to calculate dynamic impacts on the operator in terms of different structural and performance parameters of the machine and considering combination of external pertrubation influences was proposed.

  14. Operator/contractor teamwork is the key to performance improvement

    International Nuclear Information System (INIS)

    Robins, K.B.; Roberts, J.D.M.

    1996-01-01

    The contract strategies developed by the two major E and P companies operating in the North Sea emphasize teamwork between operator and contractors to achieve the common goal of maximizing project value. These strategies have had significant repercussions across the whole industry. This paper compares these strategies and concludes that although they are structurally different, they have the same fundamental objectives. It describes the evolution of what these operators consider to be their core business, with the resultant changing roles for both operator and contractor staff. Several examples of results achieved through implementing these changes are described, highlighting the need for a structured performance measurement system to quantify the success of these initiatives. Finally, the potential for even greater efficiency improvements through further industry-wide cooperation is emphasized

  15. Survey of methods for improving operator acceptance of computerized aids

    International Nuclear Information System (INIS)

    Frey, P.R.; Kisner, R.A.

    1982-04-01

    The success of current attempts to improve the operational performance and safety of nuclear power plants by installing computerized operational aids in the control rooms is dependent, in part, on the operator's attitude toward the aid. Utility experience with process computer systems indicates that problems may already exist with operator acceptance of computerized aids. The growth of the role that computers have in nuclear power plants makes user acceptance of computer technology an important issue for the nuclear industry. The purpose of this report is to draw from the literature factors related to user acceptance of computerized equipment that may also be applicable to the acceptance of computerized aids used in the nuclear power plant control room

  16. Survey of methods for improving operator acceptance of computerized aids

    Energy Technology Data Exchange (ETDEWEB)

    Frey, P. R.; Kisner, R. A.

    1982-04-01

    The success of current attempts to improve the operational performance and safety of nuclear power plants by installing computerized operational aids in the control rooms is dependent, in part, on the operator's attitude toward the aid. Utility experience with process computer systems indicates that problems may already exist with operator acceptance of computerized aids. The growth of the role that computers have in nuclear power plants makes user acceptance of computer technology an important issue for the nuclear industry. The purpose of this report is to draw from the literature factors related to user acceptance of computerized equipment that may also be applicable to the acceptance of computerized aids used in the nuclear power plant control room.

  17. Inter- and intra-operator reliability and repeatability of shear wave elastography in the liver: a study in healthy volunteers.

    Science.gov (United States)

    Hudson, John M; Milot, Laurent; Parry, Craig; Williams, Ross; Burns, Peter N

    2013-06-01

    This study assessed the reproducibility of shear wave elastography (SWE) in the liver of healthy volunteers. Intra- and inter-operator reliability and repeatability were quantified in three different liver segments in a sample of 15 subjects, scanned during four independent sessions (two scans on day 1, two scans 1 wk later) by two operators. A total of 1440 measurements were made. Reproducibility was assessed using the intra-class correlation coefficient (ICC) and a repeated measures analysis of variance. The shear wave speed was measured and used to estimate Young's modulus using the Supersonics Imagine Aixplorer. The median Young's modulus measured through the inter-costal space was 5.55 ± 0.74 kPa. The intra-operator reliability was better for same-day evaluations (ICC = 0.91) than the inter-operator reliability (ICC = 0.78). Intra-observer agreement decreased when scans were repeated on a different day. Inter-session repeatability was between 3.3% and 9.9% for intra-day repeated scans, compared with to 6.5%-12% for inter-day repeated scans. No significant difference was observed in subjects with a body mass index greater or less than 25 kg/m(2). Copyright © 2013 World Federation for Ultrasound in Medicine & Biology. Published by Elsevier Inc. All rights reserved.

  18. Toward feasible, valid, and reliable video-based assessments of technical surgical skills in the operating room

    DEFF Research Database (Denmark)

    Aggarwal, R.; Grantcharov, T.; Moorthy, K.

    2008-01-01

    .72). Conclusions: Video-based technical skills evaluation in the operating room is feasible, valid and reliable. Global rating scales hold promise for summative assessment, though further work is necessary to elucidate the value of procedural rating scales Udgivelsesdato: 2008/2......Objective: To determine the feasibility, validity, inter-rater, and intertest reliability of 4 previously published video-based rating scales, for technical skills assessment on a benchmark laparoscopic procedure. Summary Background Data: Assessment of technical skills is crucial...... to the demonstration and maintenance of competent healthcare practitioners. Traditional assessment methods are prone to subjectivity through a lack of proven validity and reliability. Methods: Nineteen surgeons (6 novice and 13 experienced) performed a median of 2 laparoscopic cholecystectomies each (range 1-5) on 53...

  19. [Examination of safety improvement by failure record analysis that uses reliability engineering].

    Science.gov (United States)

    Kato, Kyoichi; Sato, Hisaya; Abe, Yoshihisa; Ishimori, Yoshiyuki; Hirano, Hiroshi; Higashimura, Kyoji; Amauchi, Hiroshi; Yanakita, Takashi; Kikuchi, Kei; Nakazawa, Yasuo

    2010-08-20

    How the maintenance checks of the medical treatment system, including start of work check and the ending check, was effective for preventive maintenance and the safety improvement was verified. In this research, date on the failure of devices in multiple facilities was collected, and the data of the trouble repair record was analyzed by the technique of reliability engineering. An analysis of data on the system (8 general systems, 6 Angio systems, 11 CT systems, 8 MRI systems, 8 RI systems, and the radiation therapy system 9) used in eight hospitals was performed. The data collection period assumed nine months from April to December 2008. Seven items were analyzed. (1) Mean time between failures (MTBF) (2) Mean time to repair (MTTR) (3) Mean down time (MDT) (4) Number found by check in morning (5) Failure generation time according to modality. The classification of the breakdowns per device, the incidence, and the tendency could be understood by introducing reliability engineering. Analysis, evaluation, and feedback on the failure generation history are useful to keep downtime to a minimum and to ensure safety.

  20. Improved Reliability of Small Molecule Organic Solar Cells by Double Anode Buffer Layers

    Directory of Open Access Journals (Sweden)

    Pao-Hsun Huang

    2014-01-01

    Full Text Available An optimized hybrid planar heterojunction (PHJ of small molecule organic solar cells (SM-OSCs based on copper phthalocyanine (CuPc as donor and fullerene (C60 as acceptor was fabricated, which obviously enhanced the performance of device by sequentially using both MoO3 and pentacene as double anode buffer layers (ABL, also known as hole extraction layer (HEL. A series of the vacuum-deposited ABL, acting as an electron and exciton blocking layer, were examined for their characteristics in SM-OSCs. The performance and reliability were compared between conventional ITO/ABL/CuPc/C60/BCP/Ag cells and the new ITO/double ABL/CuPc/C60/BCP/Ag cells. The effect on the electrical properties of these materials was also investigated to obtain the optimal thickness of ABL. The comparison shows that the modified cell has an enhanced reliability compared to traditional cells. The improvement of lifetime was attributed to the idea of double layers to prevent humidity and oxygen from diffusing into the active layer. We demonstrated that the interfacial extraction layers are necessary to avoid degradation of device. That is to say, in normal temperature and pressure, a new avenue for the device within double buffer layers has exhibited the highest values of open circuit voltage (Voc, fill factor (FF, and lifetime in this work compared to monolayer of ABL.