Validity, Reliability, and Performance Determinants of a New Job-Specific Anaerobic Work Capacity Test for the Norwegian Navy Special Operations Command.

Science.gov (United States)

Angeltveit, Andreas; Paulsen, Gøran; Solberg, Paul A; Raastad, Truls

2016-02-01

Operators in Special Operation Forces (SOF) have a particularly demanding profession where physical and psychological capacities can be challenged to the extremes. The diversity of physical capacities needed depend on the mission. Consequently, tests used to monitor SOF operators' physical fitness should cover a broad range of physical capacities. Whereas tests for strength and aerobic endurance are established, there is no test for specific anaerobic work capacity described in the literature. The purpose of this study was therefore to evaluate the reliability, validity, and to identify performance determinants of a new test developed for testing specific anaerobic work capacity in SOF operators. Nineteen active young students were included in the concurrent validity part of the study. The students performed the evacuation (EVAC) test 3 times and the results were compared for reliability and with performance in the Wingate cycle test, 300-m sprint, and a maximal accumulated oxygen deficit (MAOD) test. In part II of the study, 21 Norwegian Navy Special Operations Command operators conducted the EVAC test, anthropometric measurements, a dual x-ray absorptiometry scan, leg press, isokinetic knee extensions, maximal oxygen uptake test, and countermovement jump (CMJ) test. The EVAC test showed good reliability after 1 familiarization trial (intraclass correlation = 0.89; coefficient of variance = 3.7%). The EVAC test correlated well with the Wingate test (r = -0.68), 300-m sprint time (r = 0.51), and 300-m mean power (W) (r = -0.67). No significant correlation was found with the MAOD test. In part II of the study, height, body mass, lean body mass, isokinetic knee extension torque, maximal oxygen uptake, and maximal power in a CMJ was significantly correlated with performance in the EVAC test. The EVAC test is a reliable and valid test for anaerobic work capacity for SOF operators, and muscle mass, leg strength, and leg power seem to be the most important determinants

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

Nuclear performance and reliability

International Nuclear Information System (INIS)

Rothwell, G.

1993-01-01

If fewer forced outages are a sign of improved safety, nuclear power plants have become safer and more productive. There has been a significant improvement in nuclear power plant performance, due largely to a decline in the forced outage rate and a dramatic drop in the average number of forced outages per fuel cycle. If fewer forced outages are a sign of improved safety, nuclear power plants have become safer and more productive over time. To encourage further increases in performance, regulatory incentive schemes should reward reactor operators for improved reliability and safety, as well as for improved performance

Delivering high performance BWR fuel reliably

International Nuclear Information System (INIS)

Schardt, J.F.

1998-01-01

Utilities are under intense pressure to reduce their production costs in order to compete in the increasingly deregulated marketplace. They need fuel, which can deliver high performance to meet demanding operating strategies. GE's latest BWR fuel design, GE14, provides that high performance capability. GE's product introduction process assures that this performance will be delivered reliably, with little risk to the utility. (author)

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

Delivering high performance BWR fuel reliably

Energy Technology Data Exchange (ETDEWEB)

Schardt, J.F. [GE Nuclear Energy, Wilmington, NC (United States)

1998-07-01

Utilities are under intense pressure to reduce their production costs in order to compete in the increasingly deregulated marketplace. They need fuel, which can deliver high performance to meet demanding operating strategies. GE's latest BWR fuel design, GE14, provides that high performance capability. GE's product introduction process assures that this performance will be delivered reliably, with little risk to the utility. (author)

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 ...

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

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.)

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

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

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.)

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

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.

Analysis of performance reliability of electrical and electronic equipment of car-tractor

Directory of Open Access Journals (Sweden)

Kravchenko О.Р.

2016-08-01

Full Text Available The analysis of the operational reliability of electrical and electronic equipment of vehicles, trucks Mercedes-Benz Actros 1844 LS and Volvo FH 1242, conducting international cargo transportation is performed. It is established that the equipment is reliable, which meets modern requirements, but where there is a violation of the resolution. The reason for repair work is constructive and operational factors. Distribution of efficiency and overall performance of operational reliability is retrieved. Items with more bounce are found. Common factors of violation of efficiency cars, trucks in operation, are largely different stages in warranty runs are obtained.

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.

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

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

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...

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.

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

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

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

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)

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

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...

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...

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)

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

Reliability performance of standby equipment with periodic testing

International Nuclear Information System (INIS)

Sim, S.H.

1985-11-01

In this report, the reliability performance of standby equipment subjected to periodic testing is studied. analytical expressions have been derived for reliability measures, such as the man accumulated operating time to failure, the expected number of tests between two consecutive failures, the mean time to failure following an emergency start-up and the probability of failing to complete an emergency mission of a specified duration. These results are useful for the reliability assessment of standby equipment such as combustion turbine units of the emergency power supply system, and of the Class III power system at a nuclear generating station

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)

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

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.

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)

The SACADA database for human reliability and human performance

International Nuclear Information System (INIS)

James Chang, Y.; Bley, Dennis; Criscione, Lawrence; Kirwan, Barry; Mosleh, Ali; Madary, Todd; Nowell, Rodney; Richards, Robert; Roth, Emilie M.; Sieben, Scott; Zoulis, Antonios

2014-01-01

Lack of appropriate and sufficient human performance data has been identified as a key factor affecting human reliability analysis (HRA) quality especially in the estimation of human error probability (HEP). The Scenario Authoring, Characterization, and Debriefing Application (SACADA) database was developed by the U.S. Nuclear Regulatory Commission (NRC) to address this data need. An agreement between NRC and the South Texas Project Nuclear Operating Company (STPNOC) was established to support the SACADA development with aims to make the SACADA tool suitable for implementation in the nuclear power plants' operator training program to collect operator performance information. The collected data would support the STPNOC's operator training program and be shared with the NRC for improving HRA quality. This paper discusses the SACADA data taxonomy, the theoretical foundation, the prospective data to be generated from the SACADA raw data to inform human reliability and human performance, and the considerations on the use of simulator data for HRA. Each SACADA data point consists of two information segments: context and performance results. Context is a characterization of the performance challenges to task success. The performance results are the results of performing the task. The data taxonomy uses a macrocognitive functions model for the framework. At a high level, information is classified according to the macrocognitive functions of detecting the plant abnormality, understanding the abnormality, deciding the response plan, executing the response plan, and team related aspects (i.e., communication, teamwork, and supervision). The data are expected to be useful for analyzing the relations between context, error modes and error causes in human performance

Operational safety performance of Slovak NPPs in 2005

International Nuclear Information System (INIS)

Tomek, J.

2006-01-01

In this presentation author presents operational safety performance of Slovak NPPs in 2005. Operation of Slovak NPPs in 2005 was safe and reliable, with: - high level of performance low risk; - minimal impact on the personnel, environment and public; - positive attitude to safety.

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

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)

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

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

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

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.)

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.

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)

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...

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.

Operating performance and reliability of CANDU PHWR fuel channels in Canada

International Nuclear Information System (INIS)

Strachan, B.; Brown, D.R.

1983-03-01

CANDU nuclear plants use many small-diameter high-pressure fuel channels. Good operating performance from the CANDU fuel channels has made a major contribution to the world-leading operating record of the CANDU nuclear power plants. As of 1982 December 31, there were 7,480 fuel channels installed in 18 CANDU reactors over 500 MW(e) in size. Eight of these reactors have been declared in-service and have accumulated 24,000 fuel channel-years of operation. The only significant operating problems with fuel channels have been the occurrence of leaking cracks in 70 fuel channels and a larger amount of axial creep on the early reactors than was originally provided for in the design. Both of these problems have been corrected on all CANDU reactors built since the Bruce GS 'A' station and the newer reactors should exhibit even better performance

Performance and reliability of TPE-2 device with pulsed high power source

International Nuclear Information System (INIS)

Sato, Y.; Takeda, S.; Kiyama, S.

1987-01-01

The performance and the reliability of TPE-2 device with pulsed high power sources are described. To obtain the stable high beta plasma, the reproducibility and the reliability of the pulsed power sources must be maintained. A new power crowbar system with high efficiency and the switches with low jitter time are adopted to the bank system. A monitor system which always watches the operational states of the switches is developed too, and applied for the fast rising capacitor banks of TPE-2 device. The reliable operation for the bank has been realized, based on the data of switch monitor system

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.

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

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)

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

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 ...

Measurement-based reliability/performability models

Science.gov (United States)

Hsueh, Mei-Chen

1987-01-01

Measurement-based models based on real error-data collected on a multiprocessor system are described. Model development from the raw error-data to the estimation of cumulative reward is also described. A workload/reliability model is developed based on low-level error and resource usage data collected on an IBM 3081 system during its normal operation in order to evaluate the resource usage/error/recovery process in a large mainframe system. Thus, both normal and erroneous behavior of the system are modeled. The results provide an understanding of the different types of errors and recovery processes. The measured data show that the holding times in key operational and error states are not simple exponentials and that a semi-Markov process is necessary to model the system behavior. A sensitivity analysis is performed to investigate the significance of using a semi-Markov process, as opposed to a Markov process, to model the measured system.

Validity and reliability of global operative assessment of laparoscopic skills (GOALS) in novice trainees performing a laparoscopic cholecystectomy.

Science.gov (United States)

Kramp, Kelvin H; van Det, Marc J; Hoff, Christiaan; Lamme, Bas; Veeger, Nic J G M; Pierie, Jean-Pierre E N

2015-01-01

Global Operative Assessment of Laparoscopic Skills (GOALS) assessment has been designed to evaluate skills in laparoscopic surgery. A longitudinal blinded study of randomized video fragments was conducted to estimate the validity and reliability of GOALS in novice trainees. In total, 10 trainees each performed 6 consecutive laparoscopic cholecystectomies. Sixty procedures were recorded on video. Video fragments of (1) opening of the peritoneum; (2) dissection of Calot's triangle and achievement of critical view of safety; and (3) dissection of the gallbladder from the liver bed were blinded, randomized, and rated by 2 consultant surgeons using GOALS. Also, a grade was given for overall competence. The correlation of GOALS with live observation Objective Structured Assessment of Technical Skills (OSATS) scores was calculated. Construct validity was estimated using the Friedman 2-way analysis of variance by ranks and the Wilcoxon signed-rank test. The interrater reliability was calculated using the absolute and consistency agreement 2-way random-effects model intraclass correlation coefficient. A high correlation was found between mean GOALS score (r = 0.879, p = 0.021) and mean OSATS score. The GOALS score increased significantly across the 6 procedures (p = 0.002). The trainees performed significantly better on their sixth when compared with their first cholecystectomy (p = 0.004). The consistency agreement interrater reliability was 0.37 for the mean GOALS score (p = 0.002) and 0.55 for overall competence (p < 0.001) of the 3 video fragments. The validity observed in this randomized blinded longitudinal study supports the existing evidence that GOALS is a valid tool for assessment of novice trainees. A relatively low reliability was found in this study. Copyright © 2014 Association of Program Directors in Surgery. Published by Elsevier Inc. All rights reserved.

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)

System Reliability Analysis Considering Correlation of Performances

Energy Technology Data Exchange (ETDEWEB)

Kim, Saekyeol; Lee, Tae Hee [Hanyang Univ., Seoul (Korea, Republic of); Lim, Woochul [Mando Corporation, Seongnam (Korea, Republic of)

2017-04-15

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

System Reliability Analysis Considering Correlation of Performances

International Nuclear Information System (INIS)

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

2017-01-01

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

Impact of nuclear fuel performance and reliability in a deregulated electricity market

International Nuclear Information System (INIS)

Barnoski, M.; Kaiser, B.

1997-01-01

US nuclear plants are now placing a great deal of importance on fuel performance and reliability because of their direct effect on a plant's capacity factor, availability, operating flexibility, outage duration, and worker exposure. This is reflected by utilities making fuel reliability a principal vendor evaluation criterion and making fuel performance an important bonus/penalty provision. Defect-free fuel, combined with ever improving design features, makes it possible for plants to operate at higher outputs while reducing operating and maintenance costs. Higher electrical output at lower cost is essential for US nuclear plants to meet the expected competition in a deregulated market. Through continued investment in manufacturing improvements and a vigilant, systematic design process, ABB's nuclear fuel has contributed to helping its nuclear utility customers reduce their cost of doing business. (author) 1 fig., 1 tab

Human Reliability Assessment and Human Performance Evaluation: Research and Analysis Activities at the U.S. NRC

International Nuclear Information System (INIS)

Ramey-Smith, A.M.

1998-01-01

The author indicates the themes of the six programs identified by the US NRC mission on human performance and human reliability activities. They aim at developing the technical basis to support human performance, at developing and updating a model of human performance and human reliability, at fostering national and international dialogue and cooperation efforts on human performance evaluation, at conducting operating events analysis and database development, and at providing support to human performance and human reliability inspection

Operational safety system performance alternative to the WANO's indicator

International Nuclear Information System (INIS)

Lyra, Moacir

2002-01-01

One of the operational safety performance indicators recommended by the World Association of Nuclear Operators (WANO) and adopted by Electronuclear is the reliability of the safety systems. The parameter selected to represent this indicator is the average unavailability of the trains of the concerned system. This parameter would be universally representative of the reliability for comparison purpose only if all nuclear power plants were designed within the same redundancy criteria. Considering the diversity of design criteria of the power plants in operation and based on a probabilistic approach, this paper proposes new performance indicators which are comparable regardless the redundancy criteria of the system. A case example applied to a system of the Angra 2 nuclear power plant shows that, even though with the plant in the infancy phase, the performance of the system in the period is very good. (author)

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)

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

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)

Study on the identification of main drivers affecting the performance of human operators during low power and shutdown operation

International Nuclear Information System (INIS)

Kim, Ar Ryum; Park, Jinkyun; Kim, Ji Tae; Kim, Jaewhan; Seong, Poong Hyun

2016-01-01

Highlights: • The performance of human operator during LPSD operation is significantly important. • Human performance is affected by drivers such as procedure, training, and etc. • Main drivers during LPSD operation at domestic NPPs were suggested. • It is expected that it will be used for estimating human reliability during LPSD operation. - Abstract: In the past, many researchers believed that a reactor during low power and shutdown operation was sufficiently safe. This belief has been changed by the number of accidents during such types of operation, which is significantly high. Also, it was pointed out that one of the main differences between low power and shutdown operation and full power operation is the significance of human action because there are huge amounts of human actions due to extensive maintenance and testing while automatic control and safety functions may be disabled and procedures are insufficient or incomplete. This paper suggests the main drivers in performing human reliability analysis. For this study, we reviewed eight reports relating to human performance during low power and shutdown operation and applied a root cause analysis method for 53 human or human-related events at domestic nuclear power plants to derive the main drivers that affect the occurrence of those events. As a result, several main drivers were derived, such as procedures, training, experience of personnel, and workload/stress. It is expected that these main drivers will be used to perform human reliability analysis for low power and shutdown operation.

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

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.

A Regulatory Perspective on the Performance and Reliability of Nuclear Passive Safety Systems

International Nuclear Information System (INIS)

Quan, Pham Trung; Lee, Sukho

2016-01-01

Passive safety systems have been proven to enhance the safety of NPPs. When an accident such as station blackout occurs, these systems can perform the following functions: the decay heat removal, passive safety injection, containment cooling, and the retention of radioactive materials. Following the IAEA definitions, using passive safety systems reduces reliance on active components to achieve proper actuation and not requiring operator intervention in accident conditions. That leads to the deviations in boundary conditions of the critical process or geometric parameters, which activate and operate the system to perform accident prevention and mitigation functions. The main difficulties in evaluation of functional failure of passive systems arise because of (a) lack of plant operational experience; (b) scarcity of adequate experimental data from integral test facilities or from separate effect tests in order to understand the performance characteristics of these passive systems, not only at normal operation but also during accidents and transients; (c) lack of accepted definitions of failure modes for these systems; and (d) difficulty in modeling certain physical behavior of these systems. Reliability assessment of the PSS is still one of the important issues. Several reliability methodologies such as REPAS, RMPS and ASPRA have been applied to the reliability assessments. However, some issues are remained unresolved due to lack of understanding of the treatment of dynamic failure characteristics of components of the PSS, the treatment of dynamic variation of independence process parameters such as ambient temperature and the functional failure criteria of the PSS. Dynamic reliability methodologies should be integrated in the PSS reliability analysis to have a true estimate of system failure probability. The methodology should estimate the physical variation of the parameters and the frequency of the accident sequences when the dynamic effects are considered

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...

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

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)

Multivariate performance reliability prediction in real-time

International Nuclear Information System (INIS)

Lu, S.; Lu, H.; Kolarik, W.J.

2001-01-01

This paper presents a technique for predicting system performance reliability in real-time considering multiple failure modes. The technique includes on-line multivariate monitoring and forecasting of selected performance measures and conditional performance reliability estimates. The performance measures across time are treated as a multivariate time series. A state-space approach is used to model the multivariate time series. Recursive forecasting is performed by adopting Kalman filtering. The predicted mean vectors and covariance matrix of performance measures are used for the assessment of system survival/reliability with respect to the conditional performance reliability. The technique and modeling protocol discussed in this paper provide a means to forecast and evaluate the performance of an individual system in a dynamic environment in real-time. The paper also presents an example to demonstrate the technique

On the plant operators performance during earthquake

International Nuclear Information System (INIS)

Kitada, Y.; Yoshimura, S.; Abe, M.; Niwa, H.; Yoneda, T.; Matsunaga, M.; Suzuki, T.

1994-01-01

There is little data on which to judge the performance of plant operators during and after strong earthquakes. In order to obtain such data to enhance the reliability on the plant operation, a Japanese utility and a power plant manufacturer carried out a vibration test using a shaking table. The purpose of the test was to investigate operator performance, i.e., the quickness and correctness in switch handling and panel meter read-out. The movement of chairs during earthquake as also of interest, because if the chairs moved significantly or turned over during a strong earthquake, some arresting mechanism would be required for the chair. Although there were differences between the simulated earthquake motions used and actual earthquakes mainly due to the specifications of the shaking table, the earthquake motions had almost no influence on the operators of their capability (performance) for operating the simulated console and the personal computers

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.

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.

Operational safety performance indicator system - a management tool for the self assessment of safety and reliability of nuclear power plants

International Nuclear Information System (INIS)

Anil Kumar; Mandowara, S.L.; Mittal, S.

2006-01-01

Operational Safety Performance Indicator system is one of the self assessment tools for station management to monitor safety and reliability of nuclear power plants. It provides information to station management about the performance of various areas of the plants by means of different colours of relevant performance indicators. Such systems have been implemented at many nuclear power plants in the world and have been considered as strength during WANO Peer Review. IAEA had a Coordinated Research Programme (CRP) on this with several countries participating including India. In NPCIL this system has been implemented in KAPS about a year back and found very useful in identifying areas which needs to be given more attention. Based on the KAPS feedback Implementation of this system has been taken up in RAPS-3 and 4 and KGS-l and 2. (author)

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)

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

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.

MEASUREMENT: ACCOUNTING FOR RELIABILITY IN PERFORMANCE ESTIMATES.

Science.gov (United States)

Waterman, Brian; Sutter, Robert; Burroughs, Thomas; Dunagan, W Claiborne

2014-01-01

When evaluating physician performance measures, physician leaders are faced with the quandary of determining whether departures from expected physician performance measurements represent a true signal or random error. This uncertainty impedes the physician leader's ability and confidence to take appropriate performance improvement actions based on physician performance measurements. Incorporating reliability adjustment into physician performance measurement is a valuable way of reducing the impact of random error in the measurements, such as those caused by small sample sizes. Consequently, the physician executive has more confidence that the results represent true performance and is positioned to make better physician performance improvement decisions. Applying reliability adjustment to physician-level performance data is relatively new. As others have noted previously, it's important to keep in mind that reliability adjustment adds significant complexity to the production, interpretation and utilization of results. Furthermore, the methods explored in this case study only scratch the surface of the range of available Bayesian methods that can be used for reliability adjustment; further study is needed to test and compare these methods in practice and to examine important extensions for handling specialty-specific concerns (e.g., average case volumes, which have been shown to be important in cardiac surgery outcomes). Moreover, it's important to note that the provider group average as a basis for shrinkage is one of several possible choices that could be employed in practice and deserves further exploration in future research. With these caveats, our results demonstrate that incorporating reliability adjustment into physician performance measurements is feasible and can notably reduce the incidence of "real" signals relative to what one would expect to see using more traditional approaches. A physician leader who is interested in catalyzing performance improvement

Individual styles of professional operator's performance for the needs of interplanetary mission.

Science.gov (United States)

Boritko, Yaroslav; Gushin, Vadim; Zavalko, Irina; Smoleevskiy, Alexandr; Dudukin, Alexandr

Maintenance of the cosmonaut’s professional performance reliability is one of the priorities of long-term space flights safety. Cosmonaut’s performance during long-term space flight decreases due to combination of the microgravity effects and inevitable degradation of skills during prolonged breaks in training. Therefore, the objective of the elaboration of countermeasures against skill decrement is very relevant. During the experiment with prolonged isolation "Mars-500" in IMBP two virtual models of professional operator’s activities were used to investigate the influence of extended isolation, monotony and confinement on professional skills degradation. One is well-known “PILOT-1” (docking to the space station), another - "VIRTU" (manned operations of planet exploration). Individual resistance to the artificial sensory conflict was estimated using computerized version of “Mirror koordinograf” with GSR registration. Two different individual performance styles, referring to the different types of response to stress, have been identified. Individual performance style, called "conservative control", manifested in permanent control of parameters, conditions and results of the operator’s activity. Operators with this performance style demonstrate high reliability in performing tasks. The drawback of the style is intensive resource expenditure - both the operator (physiological "cost") and the technical system operated (fuel, time). This style is more efficient while executing tasks that require long work with high reliability required according to a detailed protocol, such as orbital flight. Individual style, called "exploratory ", manifested in the search of new ways of task fulfillment. This style is accompanied by partial, periodic lack of control of the conditions and result of operator’s activity due to flexible approach to the tasks perfect implementation. Operators spent less resource (fuel, time, lower physiological "cost") due to high self

Equipment Reliability Program in NPP Krsko

International Nuclear Information System (INIS)

Skaler, F.; Djetelic, N.

2006-01-01

Operation that is safe, reliable, effective and acceptable to public is the common message in a mission statement of commercial nuclear power plants (NPPs). To fulfill these goals, nuclear industry, among other areas, has to focus on: 1 Human Performance (HU) and 2 Equipment Reliability (EQ). The performance objective of HU is as follows: The behaviors of all personnel result in safe and reliable station operation. While unwanted human behaviors in operations mostly result directly in the event, the behavior flaws either in the area of maintenance or engineering usually cause decreased equipment reliability. Unsatisfied Human performance leads even the best designed power plants into significant operating events, which can be found as well-known examples in nuclear industry. Equipment reliability is today recognized as the key to success. While the human performance at most NPPs has been improving since the start of WANO / INPO / IAEA evaluations, the open energy market has forced the nuclear plants to reduce production costs and operate more reliably and effectively. The balance between these two (opposite) goals has made equipment reliability even more important for safe, reliable and efficient production. Insisting on on-line operation by ignoring some principles of safety could nowadays in a well-developed safety culture and human performance environment exceed the cost of electricity losses. In last decade the leading USA nuclear companies put a lot of effort to improve equipment reliability primarily based on INPO Equipment Reliability Program AP-913 at their NPP stations. The Equipment Reliability Program is the key program not only for safe and reliable operation, but also for the Life Cycle Management and Aging Management on the way to the nuclear power plant life extension. The purpose of Equipment Reliability process is to identify, organize, integrate and coordinate equipment reliability activities (preventive and predictive maintenance, maintenance

Photovoltaic performance and reliability workshop

Energy Technology Data Exchange (ETDEWEB)

Mrig, L. [ed.

1993-12-01

This workshop was the sixth in a series of workshops sponsored by NREL/DOE under the general subject of photovoltaic testing and reliability during the period 1986--1993. PV performance and PV reliability are at least as important as PV cost, if not more. In the US, PV manufacturers, DOE laboratories, electric utilities, and others are engaged in the photovoltaic reliability research and testing. This group of researchers and others interested in the field were brought together to exchange the technical knowledge and field experience as related to current information in this evolving field of PV reliability. The papers presented here reflect this effort since the last workshop held in September, 1992. The topics covered include: cell and module characterization, module and system testing, durability and reliability, system field experience, and standards and codes.

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

Operating performance of the prototype heavy water reactor Fugen

International Nuclear Information System (INIS)

1984-01-01

Since the full scale operation was started in March, 1979, the ATR Fugen power station has been verifying the performance and reliability of the machinery and equipment, uranium-plutonium mixed oxide fuel and so on, and obtaining the technical prospect for putting ATRs in practical use by accumulating operation and maintenance techniques, through about five years of operation. In this report, the operational results of the Fugen power station are described. Fugen is a heavy water-moderated, boiling light water-cooled, pressure tube type reactor with 165 MWe output. As of the end of March, 1984, the total generated electric power was about 4.3 billion kWh, and the operation time was about 27,000 hours. The mean capacity ratio reached 58.8%. During the operation period, troubles including plant shutdown occurred eight times, but generally the performance and reliability of the machinery and equipment have been good. 580 fuels including 284 MOX fuels have been charged, but fuel breaking did not occur at all. The consumption of heavy water and the leak of tritium did not cause problem. The management of the core and fuel, the management of maintenance, the quality control of cooling water and heavy water, radiation control and the management of wastes are reported. (Kako, I.)

Proceedings from Specialists Meeting on human performance in operational events

International Nuclear Information System (INIS)

1998-01-01

This conference on human performance in operational events is composed of 34 papers, grouped in 11 sessions. After an invited contribution on the human factor in the nuclear industry, the sessions are: session 1 (Operational events: Human performance in operational events - how to improve it?, Human performance research strategies for human performance, The development of a model of control room operator cognition), session 2 (Operational response: A study of the recovery from 120 events, Empirical study of the influence of organizational and procedural characteristics on team performance in the emergency situation using plant simulators, Cognitive skills and nuclear power plant operational decision making), session 3 (PSA for Probabilistic Safety Analysis: A sensitivity study of human errors in optimizing surveillance test interval (STI) and allowed outage time (AOT) of standby safety system, Analysis of Parks nuclear power plant personnel activity during safety related event sequences, An EDF project to update the Probabilistic Human Reliability Assessment PHRA methodology), session 4 (modelling with ATHEANA: Atheana, a technique for human error analysis, an overview of its methodological basis, Common elements on operational events across technologies, Results of nuclear power plant application of new technique for human error analysis), session 5 (Regulatory practice: US.NRC Research and analysis activities concerning human reliability assessment and human performance evaluation, Introduction of simulator-based examinations and its effects on the nuclear industry, Regulatory monitoring of human performance in PWR operation in France), session 6 (Simulation: Human performance in Bavarian nuclear power plant as a preventive element, Human performance event database, Crew situation awareness, diagnoses and performance in simulated nuclear power plant process disturbances), session 7 (Operator aids: Development of a plant navigation system, Operation system

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.

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

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

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.

Effects of extended lay-off periods on performance and operator trust under adaptable automation.

Science.gov (United States)

Chavaillaz, Alain; Wastell, David; Sauer, Jürgen

2016-03-01

Little is known about the long-term effects of system reliability when operators do not use a system during an extended lay-off period. To examine threats to skill maintenance, 28 participants operated twice a simulation of a complex process control system for 2.5 h, with an 8-month retention interval between sessions. Operators were provided with an adaptable support system, which operated at one of the following reliability levels: 60%, 80% or 100%. Results showed that performance, workload, and trust remained stable at the second testing session, but operators lost self-confidence in their system management abilities. Finally, the effects of system reliability observed at the first testing session were largely found again at the second session. The findings overall suggest that adaptable automation may be a promising means to support operators in maintaining their performance at the second testing session. Copyright © 2015 Elsevier Ltd and The Ergonomics Society. All rights reserved.

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

Quantification of the reliability of personnel actions from the evaluation of actual German operational experience. Final report

International Nuclear Information System (INIS)

Preischl, W.; Fassmann, W.

2013-07-01

The results and their uncertainty bounds of PSA studies are considerably impacted by the assessment of human reliability. But the amount of available, generic data is not sufficient to evaluate all human actions considered in a modern PSA study adequately. Further the data are not sufficiently validated and rely as well as the proposed uncertainty bounds on expert judgement. This research project as well as the preceding project /GRS 10/ validated data recommended by the German PSA Guidelines and enlarged the amount of available data. The findings may contribute to an update of the German PSA Guidelines. In a first step of the project information about reportable events in German nuclear power plants with observed human errors (event reports, expert statements, technical documents, interviews and plant walk downs with subject matter experts from the plants) were analysed. The investigation resulted in 67 samples describing personal activities, performance conditions, the number of observed errors and the number of action performance. In a second step a new methodology was developed and applied in a pilot plant. The objective was to identify undoubtedly error free safety relevant actions, their performance conditions, and frequency as well as to prove and demonstrate that probabilistic data can be derived from that operational experience (OE). The application in the pilot plant resulted in 18 ''error free'' samples characterizing human reliability. All available samples were evaluated by use of the method of Bayes. That commonly accepted methodology was applied in order to derive probabilistic data based on samples taken from operational experience. A thorough analysis of the obtained results shows that both data sources (OE reportable events, OE with undoubtedly error free action performance) provide data with comparable quality and validity. At the end of the research project the following products are available. - Methods to select samples

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.

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.

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...

Application of objective clinical human reliability analysis (OCHRA) in assessment of technical performance in laparoscopic rectal cancer surgery.

Science.gov (United States)

Foster, J D; Miskovic, D; Allison, A S; Conti, J A; Ockrim, J; Cooper, E J; Hanna, G B; Francis, N K

2016-06-01

Laparoscopic rectal resection is technically challenging, with outcomes dependent upon technical performance. No robust objective assessment tool exists for laparoscopic rectal resection surgery. This study aimed to investigate the application of the objective clinical human reliability analysis (OCHRA) technique for assessing technical performance of laparoscopic rectal surgery and explore the validity and reliability of this technique. Laparoscopic rectal cancer resection operations were described in the format of a hierarchical task analysis. Potential technical errors were defined. The OCHRA technique was used to identify technical errors enacted in videos of twenty consecutive laparoscopic rectal cancer resection operations from a single site. The procedural task, spatial location, and circumstances of all identified errors were logged. Clinical validity was assessed through correlation with clinical outcomes; reliability was assessed by test-retest. A total of 335 execution errors identified, with a median 15 per operation. More errors were observed during pelvic tasks compared with abdominal tasks (p technical performance of laparoscopic rectal surgery.

Study on Performance Shaping Factors (PSFs) Quantification Method in Human Reliability Analysis (HRA)

International Nuclear Information System (INIS)

Kim, Ar Ryum; Jang, Inseok Jang; Seong, Poong Hyun; Park, Jinkyun; Kim, Jong Hyun

2015-01-01

The purpose of HRA implementation is 1) to achieve the human factor engineering (HFE) design goal of providing operator interfaces that will minimize personnel errors and 2) to conduct an integrated activity to support probabilistic risk assessment (PRA). For these purposes, various HRA methods have been developed such as technique for human error rate prediction (THERP), simplified plant analysis risk human reliability assessment (SPAR-H), cognitive reliability and error analysis method (CREAM) and so on. In performing HRA, such conditions that influence human performances have been represented via several context factors called performance shaping factors (PSFs). PSFs are aspects of the human's individual characteristics, environment, organization, or task that specifically decrements or improves human performance, thus respectively increasing or decreasing the likelihood of human errors. Most HRA methods evaluate the weightings of PSFs by expert judgment and explicit guidance for evaluating the weighting is not provided. It has been widely known that the performance of the human operator is one of the critical factors to determine the safe operation of NPPs. HRA methods have been developed to identify the possibility and mechanism of human errors. In performing HRA methods, the effect of PSFs which may increase or decrease human error should be investigated. However, the effect of PSFs were estimated by expert judgment so far. Accordingly, in order to estimate the effect of PSFs objectively, the quantitative framework to estimate PSFs by using PSF profiles is introduced in this paper

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

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

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.

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)

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

Energy Technology Data Exchange (ETDEWEB)

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

2010-02-15

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

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

International Nuclear Information System (INIS)

Soszynska, Joanna

2010-01-01

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

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.

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.

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)

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)

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)

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)

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

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

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

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.

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

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.

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.

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.

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

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

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

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

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.)

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.)

Study on evaluation index system of operational performance of municipal wastewater treatment plants in China

Science.gov (United States)

Xiaoxin, Zhang; Jin, Huang; Ling, Lin; Yan, Li

2018-05-01

According to the undeveloped evaluation method for the operational performance of the municipal wastewater treatment plants, this paper analyzes the policies related to sewage treatment industry based on the investigation of the municipal wastewater treatment plants. The applicable evaluation method for the operational performance was proposed from environmental protection performance, resources and energy consumption, technical and economic performance, production management and main equipment, providing a reliable basis for scientific evaluation of the operation as well as improving the operational performance of municipal wastewater treatment plant.

Performance and Reliability of Wind Turbines: A Review

Directory of Open Access Journals (Sweden)

Sebastian Pfaffel

2017-11-01

Full Text Available Performance (availability and yield and reliability of wind turbines can make the difference between success and failure of wind farm projects and these factors are vital to decrease the cost of energy. During the last years, several initiatives started to gather data on the performance and reliability of wind turbines on- and offshore and published findings in different journals and conferences. Even though the scopes of the different initiatives are similar, every initiative follows a different approach and results are therefore difficult to compare. The present paper faces this issue, collects results of different initiatives and harmonizes the results. A short description and assessment of every considered data source is provided. To enable this comparison, the existing reliability characteristics are mapped to a system structure according to the Reference Designation System for Power Plants (RDS-PP®. The review shows a wide variation in the performance and reliability metrics of the individual initiatives. Especially the comparison on onshore wind turbines reveals significant differences between the results. Only a few publications are available on offshore wind turbines and the results show an increasing performance and reliability of offshore wind turbines since the first offshore wind farms were erected and monitored.

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

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.

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

Material and design considerations of FBGA reliability performance

International Nuclear Information System (INIS)

Lee, Teck Kheng; Ng, T.C.; Chai, Y.M.

2004-01-01

FBGA package reliability is usually assessed through the conventional approaches of die attach and mold compound material optimization. However, with the rapid changes and fast-moving pace of electronic packaging and the introduction of new soldermask and core materials, substrate design has also become a critical factor in determining overall package reliability. The purpose of this paper is to understand the impact design and soldermask material of a rigid substrate on overall package reliability. Three different soldermask patterns with a matrix of different die attach, mold compound, and soldermask materials are assessed using the moisture sensitivity test (MST). Package reliability is also assessed through the use of temperature cycling (T/C) at conditions 'B' and 'C'. For material optimization, three different mold compounds and die attach materials are used. Material adhesion between different die attach materials and soldermask materials are obtained through die shear performed at various temperatures and preset moisture conditions. A study correlating the different packaging material properties and their relative adhesion strengths with overall package reliability in terms of both MST and T/C performance was performed. Soldermask design under the die pads was found to affect package reliability. For example, locating vias at the edge of the die is not desirable because the vias acts as initiation point for delamination and moisture-induced failure. Through die shear testing, soldermask B demonstrated higher adhesion properties compared to soldermask A across several packaging materials and enhanced the overall package reliability in terms of both MST and T/C performance. Both MST JEDEC level 1 and the T/C of 'B' and 'C' at 1000 cycles have been achieved through design and package material optimization

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

A new approach for reliability analysis with time-variant performance characteristics

International Nuclear Information System (INIS)

Wang, Zequn; Wang, Pingfeng

2013-01-01

Reliability represents safety level in industry practice and may variant due to time-variant operation condition and components deterioration throughout a product life-cycle. Thus, the capability to perform time-variant reliability analysis is of vital importance in practical engineering applications. This paper presents a new approach, referred to as nested extreme response surface (NERS), that can efficiently tackle time dependency issue in time-variant reliability analysis and enable to solve such problem by easily integrating with advanced time-independent tools. The key of the NERS approach is to build a nested response surface of time corresponding to the extreme value of the limit state function by employing Kriging model. To obtain the data for the Kriging model, the efficient global optimization technique is integrated with the NERS to extract the extreme time responses of the limit state function for any given system input. An adaptive response prediction and model maturation mechanism is developed based on mean square error (MSE) to concurrently improve the accuracy and computational efficiency of the proposed approach. With the nested response surface of time, the time-variant reliability analysis can be converted into the time-independent reliability analysis and existing advanced reliability analysis methods can be used. Three case studies are used to demonstrate the efficiency and accuracy of NERS approach

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

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

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)

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)

Managing wind turbine reliability and maintenance via performance-based contract

DEFF Research Database (Denmark)

Jin, Tongdan; Ding, Yi; Guo, Huairui

2012-01-01

between system cost, reliability and spare parts stocking. This analytical insight into the system performance allows the turbine manufacturer to optimize design, production, and after-sales services. The study aims to create a theoretical basis to facilitate the transition of the maintenance paradigm......Performance-based contracting (PBC) is reshaping the acquisition, operation, and maintenance of capital equipment. Under the PBC scheme, we propose a holistic approach for lowering the cost of wind turbine ownership while meeting the availability requirement. Our effects are focused on integrated...... firms who design and market wind turbines, and also provide maintenance and repair service. PBC differs from conventional service contracts in that the wind farmers compensate the service provider for the system performance, not the spare parts and repair labor. We explore the analytical relationship...

Track 2- major components reliability and materials issues. Some performance indicators of PWR steam generators

International Nuclear Information System (INIS)

Milivojevic, S.; Spasojevic, D.; Riznic, J.

2001-01-01

The monitoring of operational performance is a crucial aspect of the management of equipment operation and maintenance in many industries, including nuclear and thermal power plants. Monitoring involves the collection and analysis of data on the operation. In these paper an analysis was made of steam generators in operation, i.e., their malfunctions during the plant life cycle with the aim of studying the characteristics of failure rate and repair rate. These values are necessary parameters if we are to determine the reliability and availability of the steam generator as a basis for the analysis of its effect on the safety and efficiency of the nuclear power plant. We analyzed IAEA available data for period from 1971 to 1998. Each steam generator was monitored individually during plants' lifetime. The data on steam generator failures were presented in uniform format, allowing the consistency in failure classification and data reporting. Operational presence of the analyzed steam generators is given for each calendar year and each lifetime year: the failure rate l and repair rate m with associated boundaries are calculated. The general trends in calendar years performance indicators (μ) of steam generators is investigated. The distributions of lifetime l and m are formed, as a complement to the analysis of calendar years performance indicators. With aspect of steam generators influence on reliability and availability of nuclear power plants, the empirical probability distribution for failure rates and repair rates are also constructed. (author)

Material and design considerations of FBGA reliability performance

Energy Technology Data Exchange (ETDEWEB)

Lee, Teck Kheng; Ng, T.C.; Chai, Y.M

2004-09-01

FBGA package reliability is usually assessed through the conventional approaches of die attach and mold compound material optimization. However, with the rapid changes and fast-moving pace of electronic packaging and the introduction of new soldermask and core materials, substrate design has also become a critical factor in determining overall package reliability. The purpose of this paper is to understand the impact design and soldermask material of a rigid substrate on overall package reliability. Three different soldermask patterns with a matrix of different die attach, mold compound, and soldermask materials are assessed using the moisture sensitivity test (MST). Package reliability is also assessed through the use of temperature cycling (T/C) at conditions 'B' and 'C'. For material optimization, three different mold compounds and die attach materials are used. Material adhesion between different die attach materials and soldermask materials are obtained through die shear performed at various temperatures and preset moisture conditions. A study correlating the different packaging material properties and their relative adhesion strengths with overall package reliability in terms of both MST and T/C performance was performed. Soldermask design under the die pads was found to affect package reliability. For example, locating vias at the edge of the die is not desirable because the vias acts as initiation point for delamination and moisture-induced failure. Through die shear testing, soldermask B demonstrated higher adhesion properties compared to soldermask A across several packaging materials and enhanced the overall package reliability in terms of both MST and T/C performance. Both MST JEDEC level 1 and the T/C of 'B' and 'C' at 1000 cycles have been achieved through design and package material optimization.

Operating performance of LWR nuclear generating units

International Nuclear Information System (INIS)

Pia, S.

1984-01-01

This work aims at reviewing, on the basis of historical data, the operational problem areas which explain the degree of availability and productivity achieved up to now by nuclear power plants in commercial operation in the world. The operating performance data of nuclear power plants area analysed with respect to plant type, size and other significant reference parameters and they are evaluated also by comparison with fossil generating unit data. Major performance indices data are presented for both nuclear and fossil units type and distribution of outage causes. Unplanned full outages caused by nuclear power plant equipment and components failure are particulary emphasized. The trend for unplanned full outages due to the failure of components shows decreasing numerical values in 1981 with respect to the previous years. But this result should be weighed with the increasing plant unavailability hours needed for maintenance and repair action (chiefly preventive maintenance on critical components). This means that the number and downtime of forced outage must be drastically reduced for economic reasons (production losses and problems associated with the unavailable unit unplanned replacement) as well as for plant safe and reliable operation (sudden unavailability of key components and frequency of transients associated with plant shutdown and routine startup operation)

Reliable predictions of waste performance in a geologic repository

International Nuclear Information System (INIS)

Pigford, T.H.; Chambre, P.L.

1985-08-01

Establishing reliable estimates of long-term performance of a waste repository requires emphasis upon valid theories to predict performance. Predicting rates that radionuclides are released from waste packages cannot rest upon empirical extrapolations of laboratory leach data. Reliable predictions can be based on simple bounding theoretical models, such as solubility-limited bulk-flow, if the assumed parameters are reliably known or defensibly conservative. Wherever possible, performance analysis should proceed beyond simple bounding calculations to obtain more realistic - and usually more favorable - estimates of expected performance. Desire for greater realism must be balanced against increasing uncertainties in prediction and loss of reliability. Theoretical predictions of release rate based on mass-transfer analysis are bounding and the theory can be verified. Postulated repository analogues to simulate laboratory leach experiments introduce arbitrary and fictitious repository parameters and are shown not to agree with well-established theory. 34 refs., 3 figs., 2 tabs

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.

Reliability-based performance simulation for optimized pavement maintenance

International Nuclear Information System (INIS)

Chou, Jui-Sheng; Le, Thanh-Son

2011-01-01

Roadway pavement maintenance is essential for driver safety and highway infrastructure efficiency. However, regular preventive maintenance and rehabilitation (M and R) activities are extremely costly. Unfortunately, the funds available for the M and R of highway pavement are often given lower priority compared to other national development policies, therefore, available funds must be allocated wisely. Maintenance strategies are typically implemented by optimizing only the cost whilst the reliability of facility performance is neglected. This study proposes a novel algorithm using multi-objective particle swarm optimization (MOPSO) technique to evaluate the cost-reliability tradeoff in a flexible maintenance strategy based on non-dominant solutions. Moreover, a probabilistic model for regression parameters is employed to assess reliability-based performance. A numerical example of a highway pavement project is illustrated to demonstrate the efficacy of the proposed MOPSO algorithms. The analytical results show that the proposed approach can help decision makers to optimize roadway maintenance plans. - Highlights: →A novel algorithm using multi-objective particle swarm optimization technique. → Evaluation of the cost-reliability tradeoff in a flexible maintenance strategy. → A probabilistic model for regression parameters is employed to assess reliability-based performance. → The proposed approach can help decision makers to optimize roadway maintenance plans.

Reliability-based performance simulation for optimized pavement maintenance

Energy Technology Data Exchange (ETDEWEB)

Chou, Jui-Sheng, E-mail: jschou@mail.ntust.edu.tw [Department of Construction Engineering, National Taiwan University of Science and Technology (Taiwan Tech), 43 Sec. 4, Keelung Rd., Taipei 106, Taiwan (China); Le, Thanh-Son [Department of Construction Engineering, National Taiwan University of Science and Technology (Taiwan Tech), 43 Sec. 4, Keelung Rd., Taipei 106, Taiwan (China)

2011-10-15

Roadway pavement maintenance is essential for driver safety and highway infrastructure efficiency. However, regular preventive maintenance and rehabilitation (M and R) activities are extremely costly. Unfortunately, the funds available for the M and R of highway pavement are often given lower priority compared to other national development policies, therefore, available funds must be allocated wisely. Maintenance strategies are typically implemented by optimizing only the cost whilst the reliability of facility performance is neglected. This study proposes a novel algorithm using multi-objective particle swarm optimization (MOPSO) technique to evaluate the cost-reliability tradeoff in a flexible maintenance strategy based on non-dominant solutions. Moreover, a probabilistic model for regression parameters is employed to assess reliability-based performance. A numerical example of a highway pavement project is illustrated to demonstrate the efficacy of the proposed MOPSO algorithms. The analytical results show that the proposed approach can help decision makers to optimize roadway maintenance plans. - Highlights: > A novel algorithm using multi-objective particle swarm optimization technique. > Evaluation of the cost-reliability tradeoff in a flexible maintenance strategy. > A probabilistic model for regression parameters is employed to assess reliability-based performance. > The proposed approach can help decision makers to optimize roadway maintenance plans.

SGHWR fuel performance, safety and reliability

International Nuclear Information System (INIS)

Pickman, D.O.; Inglis, G.H.

1977-01-01

The design principles involved in fuel pins and elements need to take account of the sometimes conflicting requirements of performance, safety and reliability. The principal factors involved in this optimisation are discussed and it is shown from fuel irradiation experience in the Winfrith S.G.H.W.R. that the necessary bias toward safety has not resulted in a reliability level lower than that shown by other successful water reactor designs. Reliability has important economic implications and has to be paid for. By a detailed evaluation of S.G.H.W.R. fuel defects it is shown that very few defects can be shown to be related to design, rating or burn-up. This demonstrates that economic aspects have not over-ridden necessary criteria that must be met to achieve the desirable reliability level. It is possible that large-scale experience with S.G.H.W.R. fuel may eventually demonstrate that the balance is too much in favour of reliability and consideration may be given to whether design changes favouring economy could be achieved without compromising safety. The safety criteria applied to S.G.H.W.R. fuel are designed to avoid any possibility of a temperature runaway in any credible accident situation. The philosophy and supporting experimental work programme are outlined and the fuel design features which particularly contribute to maximising safety margins are outlined. Reference is made to new 60 pin fuel element to be used in the commercial S.G.H.W.R.'s and how it compares in design and performance aspects with the 36 pin element that has been used to date in the Winfrith S.G.H.W.R

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.

Fuel reliability experience in Finland

International Nuclear Information System (INIS)

Kekkonen, L.

2015-01-01

Four nuclear reactors have operated in Finland now for 35-38 years. The two VVER-440 units at Loviisa Nuclear Power Plant are operated by Fortum and two BWR’s in Olkiluoto are operated by Teollisuuden Voima Oyj (TVO). The fuel reliability experience of the four reactors operating currently in Finland has been very good and the fuel failure rates have been very low. Systematic inspection of spent fuel assemblies, and especially all failed assemblies, is a good practice that is employed in Finland in order to improve fuel reliability and operational safety. Investigation of the root cause of fuel failures is important in developing ways to prevent similar failures in the future. The operational and fuel reliability experience at the Loviisa Nuclear Power Plant has been reported also earlier in the international seminars on WWER Fuel Performance, Modelling and Experimental Support. In this paper the information on fuel reliability experience at Loviisa NPP is updated and also a short summary of the fuel reliability experience at Olkiluoto NPP is given. Keywords: VVER-440, fuel reliability, operational experience, poolside inspections, fuel failure identification. (author)

Operator performance in non-destructive testing: A study of operator performance in a performance test

Energy Technology Data Exchange (ETDEWEB)

Enkvist, J.; Edland, A.; Svenson, Ola [Stockholm Univ. (Sweden). Dept. of Psychology

2000-05-15

In the process industries there is a need of inspecting the integrity of critical components without disrupting the process. Such in-service inspections are typically performed with non-destructive testing (NDT). In NDT the task of the operator is to (based on diagnostic information) decide if the component can remain in service or not. The present study looks at the performance in NDT. The aim is to improve performance, in the long run, by exploring the operators' decision strategies and other underlying factors and to this way find out what makes some operators more successful than others. Sixteen operators performed manual ultrasonic inspections of four test pieces with the aim to detect (implanted) cracks. In addition to these performance demonstration tests (PDT), the operators performed independent ability tests and filled out questionnaires. The results show that operators who trust their gut feeling more than the procedure (when the two come to different results) and that at the same time have a positive attitude towards the procedure have a higher PDT performance. These results indicate the need for operators to be motivated and confident when performing NDT. It was also found that the operators who performed better rated more decision criteria higher in the detection phase than the operators who performed worse. For characterizing it was the other way around. Also, the operators who performed better used more time, both detecting and characterizing, than the operators who performed worse.

Operator performance in non-destructive testing: A study of operator performance in a performance test

International Nuclear Information System (INIS)

Enkvist, J.; Edland, A.; Svenson, Ola

2000-05-01

In the process industries there is a need of inspecting the integrity of critical components without disrupting the process. Such in-service inspections are typically performed with non-destructive testing (NDT). In NDT the task of the operator is to (based on diagnostic information) decide if the component can remain in service or not. The present study looks at the performance in NDT. The aim is to improve performance, in the long run, by exploring the operators' decision strategies and other underlying factors and to this way find out what makes some operators more successful than others. Sixteen operators performed manual ultrasonic inspections of four test pieces with the aim to detect (implanted) cracks. In addition to these performance demonstration tests (PDT), the operators performed independent ability tests and filled out questionnaires. The results show that operators who trust their gut feeling more than the procedure (when the two come to different results) and that at the same time have a positive attitude towards the procedure have a higher PDT performance. These results indicate the need for operators to be motivated and confident when performing NDT. It was also found that the operators who performed better rated more decision criteria higher in the detection phase than the operators who performed worse. For characterizing it was the other way around. Also, the operators who performed better used more time, both detecting and characterizing, than the operators who performed worse

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...

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

Performance reliability prediction for thermal aging based on kalman filtering

International Nuclear Information System (INIS)

Ren Shuhong; Wen Zhenhua; Xue Fei; Zhao Wensheng

2015-01-01

The performance reliability of the nuclear power plant main pipeline that failed due to thermal aging was studied by the performance degradation theory. Firstly, through the data obtained from the accelerated thermal aging experiments, the degradation process of the impact strength and fracture toughness of austenitic stainless steel material of the main pipeline was analyzed. The time-varying performance degradation model based on the state space method was built, and the performance trends were predicted by using Kalman filtering. Then, the multi-parameter and real-time performance reliability prediction model for the main pipeline thermal aging was developed by considering the correlation between the impact properties and fracture toughness, and by using the stochastic process theory. Thus, the thermal aging performance reliability and reliability life of the main pipeline with multi-parameter were obtained, which provides the scientific basis for the optimization management of the aging maintenance decision making for nuclear power plant main pipelines. (authors)

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)

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...

The development of a reliable amateur boxing performance analysis template.

Science.gov (United States)

Thomson, Edward; Lamb, Kevin; Nicholas, Ceri

2013-01-01

The aim of this study was to devise a valid performance analysis system for the assessment of the movement characteristics associated with competitive amateur boxing and assess its reliability using analysts of varying experience of the sport and performance analysis. Key performance indicators to characterise the demands of an amateur contest (offensive, defensive and feinting) were developed and notated using a computerised notational analysis system. Data were subjected to intra- and inter-observer reliability assessment using median sign tests and calculating the proportion of agreement within predetermined limits of error. For all performance indicators, intra-observer reliability revealed non-significant differences between observations (P > 0.05) and high agreement was established (80-100%) regardless of whether exact or the reference value of ±1 was applied. Inter-observer reliability was less impressive for both analysts (amateur boxer and experienced analyst), with the proportion of agreement ranging from 33-100%. Nonetheless, there was no systematic bias between observations for any indicator (P > 0.05), and the proportion of agreement within the reference range (±1) was 100%. A reliable performance analysis template has been developed for the assessment of amateur boxing performance and is available for use by researchers, coaches and athletes to classify and quantify the movement characteristics of amateur boxing.

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

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

An empirical investigation of operator performance in cognitively demanding simulated emergencies

International Nuclear Information System (INIS)

Roth, E.M.; Mumaw, R.J.; Lewis, P.M.

1994-07-01

This report documents the results of an empirical study of nuclear power plant operator performance in cognitively demanding simulated emergencies. During emergencies operators follow highly prescriptive written procedures. The objectives of the study were to understand and document what role higher-level cognitive activities such as diagnosis, or more generally 'situation assessment', play in guiding operator performance, given that operators utilize procedures in responding to the events. The study examined crew performance in variants of two emergencies: (1) an Interfacing System Loss of Coolant Accident and (2) a Loss of Heat Sink scenario. Data on operator performance were collected using training simulators at two plant sites. Up to 11 crews from each plant participated in each of two simulated emergencies for a total of 38 cases. Crew performance was videotaped and partial transcripts were produced and analyzed. The results revealed a number of instances where higher-level cognitive activities such as situation assessment and response planning enabled crews to handle aspects of the situation that were not fully addressed by the procedures. This report documents these cases and discusses their implications for the development and evaluation of training and control room aids, as well as for human reliability analyses

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)

Proof-of-Concept Demonstrations for Computation-Based Human Reliability Analysis. Modeling Operator Performance During Flooding Scenarios

Energy Technology Data Exchange (ETDEWEB)

Joe, Jeffrey Clark [Idaho National Lab. (INL), Idaho Falls, ID (United States); Boring, Ronald Laurids [Idaho National Lab. (INL), Idaho Falls, ID (United States); Herberger, Sarah Elizabeth Marie [Idaho National Lab. (INL), Idaho Falls, ID (United States); Mandelli, Diego [Idaho National Lab. (INL), Idaho Falls, ID (United States); Smith, Curtis Lee [Idaho National Lab. (INL), Idaho Falls, ID (United States)

2015-09-01

The United States (U.S.) Department of Energy (DOE) Light Water Reactor Sustainability (LWRS) program has the overall objective to help sustain the existing commercial nuclear power plants (NPPs). To accomplish this program objective, there are multiple LWRS “pathways,” or research and development (R&D) focus areas. One LWRS focus area is called the Risk-Informed Safety Margin and Characterization (RISMC) pathway. Initial efforts under this pathway to combine probabilistic and plant multi-physics models to quantify safety margins and support business decisions also included HRA, but in a somewhat simplified manner. HRA experts at Idaho National Laboratory (INL) have been collaborating with other experts to develop a computational HRA approach, called the Human Unimodel for Nuclear Technology to Enhance Reliability (HUNTER), for inclusion into the RISMC framework. The basic premise of this research is to leverage applicable computational techniques, namely simulation and modeling, to develop and then, using RAVEN as a controller, seamlessly integrate virtual operator models (HUNTER) with 1) the dynamic computational MOOSE runtime environment that includes a full-scope plant model, and 2) the RISMC framework PRA models already in use. The HUNTER computational HRA approach is a hybrid approach that leverages past work from cognitive psychology, human performance modeling, and HRA, but it is also a significant departure from existing static and even dynamic HRA methods. This report is divided into five chapters that cover the development of an external flooding event test case and associated statistical modeling considerations.

Proof-of-Concept Demonstrations for Computation-Based Human Reliability Analysis. Modeling Operator Performance During Flooding Scenarios

International Nuclear Information System (INIS)

Joe, Jeffrey Clark; Boring, Ronald Laurids; Herberger, Sarah Elizabeth Marie; Mandelli, Diego; Smith, Curtis Lee

2015-01-01

The United States (U.S.) Department of Energy (DOE) Light Water Reactor Sustainability (LWRS) program has the overall objective to help sustain the existing commercial nuclear power plants (NPPs). To accomplish this program objective, there are multiple LWRS 'pathways,' or research and development (R&D) focus areas. One LWRS focus area is called the Risk-Informed Safety Margin and Characterization (RISMC) pathway. Initial efforts under this pathway to combine probabilistic and plant multi-physics models to quantify safety margins and support business decisions also included HRA, but in a somewhat simplified manner. HRA experts at Idaho National Laboratory (INL) have been collaborating with other experts to develop a computational HRA approach, called the Human Unimodel for Nuclear Technology to Enhance Reliability (HUNTER), for inclusion into the RISMC framework. The basic premise of this research is to leverage applicable computational techniques, namely simulation and modeling, to develop and then, using RAVEN as a controller, seamlessly integrate virtual operator models (HUNTER) with 1) the dynamic computational MOOSE runtime environment that includes a full-scope plant model, and 2) the RISMC framework PRA models already in use. The HUNTER computational HRA approach is a hybrid approach that leverages past work from cognitive psychology, human performance modeling, and HRA, but it is also a significant departure from existing static and even dynamic HRA methods. This report is divided into five chapters that cover the development of an external flooding event test case and associated statistical modeling considerations.

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

Human performance for the success of equipment reliability programs

International Nuclear Information System (INIS)

Woodcock, J.

2007-01-01

Human performance is a critical element of programs directed at equipment reliability. Reliable equipment performance requires broad support from all levels of plant management and throughout all plant departments. Experience at both nuclear power plants and fuel manufacturing plants shows that human performance must be addressed during all phases of program implementation from the beginning through the establishment of a living, on-going process. At the beginning, certain organizational and management actions during the initiation of the program set the stage for successful adoption by station personnel, leading to more rapid benefits. For the long term, equipment reliability is a living process needed throughout the lifetime of a station, a program which must be motivated and measured. Sustained acceptance and participation by the plant personnel is a requirement, and culture is a key ingredient. This paper will provide an overview of key human performance issues to be considered, using the application of the INPO AP-913 Equipment Reliability Guideline as a basis and gives some best practices for training, communicating and implementing programs. The very last part includes ways to tell if the program is effective

Overall Key Performance Indicator to Optimizing Operation of High-Pressure Homogenizers for a Reliable Quantification of Intracellular Components in Pichia pastoris.

Science.gov (United States)

Garcia-Ortega, Xavier; Reyes, Cecilia; Montesinos, José Luis; Valero, Francisco

2015-01-01

The most commonly used cell disruption procedures may present lack of reproducibility, which introduces significant errors in the quantification of intracellular components. In this work, an approach consisting in the definition of an overall key performance indicator (KPI) was implemented for a lab scale high-pressure homogenizer (HPH) in order to determine the disruption settings that allow the reliable quantification of a wide sort of intracellular components. This innovative KPI was based on the combination of three independent reporting indicators: decrease of absorbance, release of total protein, and release of alkaline phosphatase activity. The yeast Pichia pastoris growing on methanol was selected as model microorganism due to it presents an important widening of the cell wall needing more severe methods and operating conditions than Escherichia coli and Saccharomyces cerevisiae. From the outcome of the reporting indicators, the cell disruption efficiency achieved using HPH was about fourfold higher than other lab standard cell disruption methodologies, such bead milling cell permeabilization. This approach was also applied to a pilot plant scale HPH validating the methodology in a scale-up of the disruption process. This innovative non-complex approach developed to evaluate the efficacy of a disruption procedure or equipment can be easily applied to optimize the most common disruption processes, in order to reach not only reliable quantification but also recovery of intracellular components from cell factories of interest.

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)

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)

Application of reliability methods in Ontario Hydro

International Nuclear Information System (INIS)

Jeppesen, R.; Ravishankar, T.J.

1985-01-01

Ontario Hydro have established a reliability program in support of its substantial nuclear program. Application of the reliability program to achieve both production and safety goals is described. The value of such a reliability program is evident in the record of Ontario Hydro's operating nuclear stations. The factors which have contributed to the success of the reliability program are identified as line management's commitment to reliability; selective and judicious application of reliability methods; establishing performance goals and monitoring the in-service performance; and collection, distribution, review and utilization of performance information to facilitate cost-effective achievement of goals and improvements. (orig.)

Accelerator Availability and Reliability Issues

Energy Technology Data Exchange (ETDEWEB)

Steve Suhring

2003-05-01

Maintaining reliable machine operations for existing machines as well as planning for future machines' operability present significant challenges to those responsible for system performance and improvement. Changes to machine requirements and beam specifications often reduce overall machine availability in an effort to meet user needs. Accelerator reliability issues from around the world will be presented, followed by a discussion of the major factors influencing machine availability.

Performance of Combustion Engineering fuel in operating PWRs

International Nuclear Information System (INIS)

Andrews, M.G.; Freeburn, H.R.; Wohlsen, W.D.

1979-01-01

Performance data on fuel assembly components from seven (7) operating reactors are presented, and discussed in detail where potential problems have occurred and been resolved. Fuel rod performance has continually improved over the last four (4) years with the gradual changeover to the current C-E fuel design. The reliability level is estimated at better than 99.99%, based on activity levels obtained through January 1979 at each plant. Control rod guide tubes have shown various degrees of wear caused by vibration of the control rods in their fully-withdrawn position. The retrofit of wear sleeves within the top portion of the affected guide tubes during routine refueling has permitted the use of these fuel assemblies with no significant loss in performance or safety margins

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)

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)

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)

EFFECT OF LUBRICANT CONTAMINATION ON THE PERFORMANCE AND RELIABILITY OF HEAT PUMPS CHARGED WITH R-407C.

Science.gov (United States)

The report gives results of the development of new data that can be used to determine the effect of mineral oil contamination on the reliability of a heat pump system operating with a new hydrofluorocarbon mixture and polyol ester lubricant, to assess any performance degradation ...

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.

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

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

Team performance measures for abnormal plant operations

International Nuclear Information System (INIS)

Montgomery, J.C.; Seaver, D.A.; Holmes, C.W.; Gaddy, C.D.; Toquam, J.L.

1990-01-01

In order to work effectively, control room crews need to possess well-developed team skills. Extensive research supports the notion that improved quality and effectiveness are possible when a group works together, rather than as individuals. The Nuclear Regulatory Commission (NRC) has recognized the role of team performance in plant safety and has attempted to evaluate licensee performance as part of audits, inspections, and reviews. However, reliable and valid criteria for team performance have not yet been adequately developed. The purpose of the present research was to develop such reliable and valid measures of team skills. Seven dimensions of team skill performance were developed on the basis of input from NRC operator licensing examiners and from the results of previous research and experience in the area. These dimensions included two-way communications, resource management, inquiry, advocacy, conflict resolution/decision-making, stress management, and team spirit. Several different types of rating formats were developed for use with these dimensions, including a modified Behaviorally Anchored Rating Scale (BARS) format and a Behavioral Frequency format. Following pilot-testing and revision, observer and control room crew ratings of team performance were obtained using 14 control room crews responding to simulator scenarios at a BWR and a PWR reactor. It is concluded, overall, that the Behavioral Frequency ratings appeared quite promising as a measure of team skills but that additional statistical analyses and other follow-up research are needed to refine several of the team skills dimensions and to make the scales fully functional in an applied setting

Approach to reliability assessment

International Nuclear Information System (INIS)

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

1975-01-01

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

SGHWR fuel performance, safety and reliability

International Nuclear Information System (INIS)

Pickman, D.O.; Inglis, G.H.

1977-05-01

The design principles involved in fuel pins and elements need to take account of the sometimes conflicting requirements of safety and reliability. The principal factors involved in this optimisation are discussed and it is shown from fuel irradiation experience in the Winfrith SGHWR that the necessary bias towards safety has not resulted in a reliability level lower than that shown by other successful water reactor designs. Reliability has important economic implications. By a detailed evaluation of SGHWR fuel defects it is shown that very few defects can be shown to be related to design, rating, or burn-up. This demonstrates that economic aspects have not over-ridden necessary criteria that most be met to achieve the desirable reliability level. It is possible that large scale experience on SGHWR fuel may eventually demonstrate that the balance is too much in favour of reliability and consideration may be given to whether design changes favouring economy could be achieved without compromising safety. The safety criteria applied to SGHWR fuel are designed to avoid any possibility of a temperature runaway in any credible accident situation. the philosophy and supporting experimental work programme are outlines and the fuel design features which particularly contribute to maximising safety margins are outlined. Reference is made to the new 60-pin fuel element to be used in the commercial SGHWRs and to its comparison in design and performance aspects with the 36-pin element that has been used to date in the Winfrith SGHWR. (author)

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...

Applications of Human Performance Reliability Evaluation Concepts and Demonstration Guidelines

Science.gov (United States)

1977-03-15

ship stops dead in the water and the AN/SQS-26 operator recommends a new heading (000°). At T + 14 minutes, the target ship begins a hard turn to...Various Simulated Conditions 82 9 Hunan Reliability for Each Simulated Operator (Baseline Run) 83 10 Human and Equipment Availabilit / under

Equipment Reliability Process in Krsko NPP

International Nuclear Information System (INIS)

Gluhak, M.

2016-01-01

To ensure long-term safe and reliable plant operation, equipment operability and availability must also be ensured by setting a group of processes to be established within the nuclear power plant. Equipment reliability process represents the integration and coordination of important equipment reliability activities into one process, which enables equipment performance and condition monitoring, preventive maintenance activities development, implementation and optimization, continuous improvement of the processes and long term planning. The initiative for introducing systematic approach for equipment reliability assuring came from US nuclear industry guided by INPO (Institute of Nuclear Power Operations) and by participation of several US nuclear utilities. As a result of the initiative, first edition of INPO document AP-913, 'Equipment Reliability Process Description' was issued and it became a basic document for implementation of equipment reliability process for the whole nuclear industry. The scope of equipment reliability process in Krsko NPP consists of following programs: equipment criticality classification, preventive maintenance program, corrective action program, system health reports and long-term investment plan. By implementation, supervision and continuous improvement of those programs, guided by more than thirty years of operating experience, Krsko NPP will continue to be on a track of safe and reliable operation until the end of prolonged life time. (author).

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...

RFA-based 589-nm guide star lasers for ESO VLT: a paradigm shift in performance, operational simplicity, reliability, and maintenance

Science.gov (United States)

Friedenauer, Axel; Karpov, Vladimir; Wei, Daoping; Hager, Manfred; Ernstberger, Bernhard; Clements, Wallace R. L.; Kaenders, Wilhelm G.

2012-07-01

Large telescopes equipped with adaptive optics require 20-25W CW 589-nm sources with emission linewidths of ~5 MHz. These Guide Star (GS) lasers should also be highly reliable and simple to operate and maintain for many years at the top of a mountain facility. Under contract from ESO, industrial partners TOPTICA and MPBC are nearing completion of the development of GS lasers for the ESO VLT, with delivery of the first of four units scheduled for December 2012. We report on the design and performance of the fully-engineered Pre-Production Unit (PPU), including system reliability/availability analysis, the successfully-concluded qualification testing, long-term component and system level tests and long-term maintenance and support planning. The chosen approach is based on ESO's patented narrow-band Raman Fiber Amplifier (EFRA) technology. A master oscillator signal from a linearly-polarized TOPTICA 20-mW, 1178-nm CW diode laser, with stabilized emission frequency and controllable linewidth up to a few MHz, is amplified in an MPBC polarization-maintaining (PM) RFA pumped by a high-power 1120-nm PM fiber laser. With efficient stimulated Brillouin scattering suppression, an unprecedented 40W of narrow-band RFA output has been obtained. This is then mode-matched into a resonant-cavity doubler with a free-spectral-range matching the sodium D2a to D2b separation, allowing simultaneous generation of an additional frequency component (D2b line) to re-pump the sodium atom electronic population. With this technique, the return flux can be increased without having to resort to electro-optical modulators and without the risk of introducing optical wave front distortions. The demonstrated output powers with doubling efficiencies >80% at 589 nm easily exceed the 20W design goal and require less than 700 W of electrical power. In summary, the fiber-based guide star lasers provide excellent beam quality and are modular, turn-key, maintenance-free, reliable, efficient, and ruggedized

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.

Applying lessons learned to enhance human performance and reduce human error for ISS operations

Energy Technology Data Exchange (ETDEWEB)

Nelson, W.R.

1998-09-01

A major component of reliability, safety, and mission success for space missions is ensuring that the humans involved (flight crew, ground crew, mission control, etc.) perform their tasks and functions as required. This includes compliance with training and procedures during normal conditions, and successful compensation when malfunctions or unexpected conditions occur. A very significant issue that affects human performance in space flight is human error. Human errors can invalidate carefully designed equipment and procedures. If certain errors combine with equipment failures or design flaws, mission failure or loss of life can occur. The control of human error during operation of the International Space Station (ISS) will be critical to the overall success of the program. As experience from Mir operations has shown, human performance plays a vital role in the success or failure of long duration space missions. The Department of Energy`s Idaho National Engineering and Environmental Laboratory (INEEL) is developed a systematic approach to enhance human performance and reduce human errors for ISS operations. This approach is based on the systematic identification and evaluation of lessons learned from past space missions such as Mir to enhance the design and operation of ISS. This paper describes previous INEEL research on human error sponsored by NASA and how it can be applied to enhance human reliability for ISS.

Establishing reliability of performance indicator of sepak takraw ...

African Journals Online (AJOL)

The aim of this study is to establish the necessary reliability in the notational analysis of sepak takraw. Two performance analysts were recruited to help in the collection of the data. The performances were analyzed based on the main performance indicators relevant to the demand of the game. Cronbach's alpha and ...

Impact of scaling on the performance and reliability degradation of metal-contacts in NEMS devices

KAUST Repository

Dadgour, Hamed F.

2011-04-01

Nano-electro-mechanical switches (NEMS) offer new possibilities for the design of ultra energy-efficient systems; however, thus far, all the fabricated NEMS devices require high supply voltages that limit their applicability for logic designs. Therefore, research is being conducted to lower the operating voltages by scaling down the physical dimensions of these devices. However, the impact of device scaling on the electrical and mechanical properties of metal contacts in NEMS devices has not been thoroughly investigated in the literature. Such a study is essential because metal contacts play a critical role in determining the overall performance and reliability of NEMS. Therefore, the comprehensive analytical study presented in this paper highlights the performance and reliability degradations of such metal contacts caused by scaling. The proposed modeling environment accurately takes into account the impact of roughness of contact surfaces, elastic/plastic deformation of contacting asperities, and various inter-molecular forces between mating surfaces (such as Van der Waals and capillary forces). The modeling results are validated and calibrated using available measurement data. This scaling analysis indicates that the key contact properties of gold contacts (resistance, stiction and wear-out) deteriorate "exponentially" with scaling. Simulation results demonstrate that reliable (stiction-free) operation of very small contact areas (≈ 6nm x 6nm) will be a daunting task due to the existence of strong surface forces. Hence, contact degradation is identified as a major problem to the scaling of NEMS transistors. © 2011 IEEE.

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.

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 ...

PEP-II RF System Operation and Performance

International Nuclear Information System (INIS)

McIntosh, P.

2005-01-01

The Low Energy Ring (LER) and High Energy Ring (HER) RF systems have operated now on PEP-II since July 1998 and have assisted in breaking all design luminosity records back in June 2001. Luminosity on PEP-II has steadily increased since then as a consequence of larger e+ and e- beam currents being accumulated. This has meant that the RF systems have inevitably been driven harder, not only to achieve these higher stored beam currents, but also to reliably keep the beams circulating whilst at the same time minimizing the number of aborts due to RF system faults. This paper details the current PEP-II RF system configurations for both rings, as well as future upgrade plans spanning the next 3-5 years. Limitations of the current RF system configurations are presented, highlighting improvement projects which will target specific areas within the RF systems to ensure that adequate operating overheads are maintained and reliable operation is assured. The Low Energy Ring (LER) and High Energy Ring (HER) RF systems have operated now on PEP-II since July 1998 and have assisted in breaking all design luminosity records back in June 2001. Luminosity on PEP-II has steadily increased since then as a consequence of larger e+ and e- beam currents being accumulated. This has meant that the RF systems have inevitably been driven harder, not only to achieve these higher stored beam currents, but also to reliably keep the beams circulating whilst at the same time minimizing the number of aborts due to RF system faults. This paper details the current PEP-II RF system configurations for both rings, as well as future upgrade plans spanning the next 3-5 years. Limitations of the current RF system configurations are presented, highlighting improvement projects which will target specific areas within the RF systems to ensure that adequate operating overheads are maintained and reliable operation is assured

Blinded evaluation of interrater reliability of an operative competency assessment tool for direct laryngoscopy and rigid bronchoscopy.

Science.gov (United States)

Ishman, Stacey L; Benke, James R; Johnson, Kaalan Erik; Zur, Karen B; Jacobs, Ian N; Thorne, Marc C; Brown, David J; Lin, Sandra Y; Bhatti, Nasir; Deutsch, Ellen S

2012-10-01

OBJECTIVES To confirm interrater reliability using blinded evaluation of a skills-assessment instrument to assess the surgical performance of resident and fellow trainees performing pediatric direct laryngoscopy and rigid bronchoscopy in simulated models. DESIGN Prospective, paired, blinded observational validation study. SUBJECTS Paired observers from multiple institutions simultaneously evaluated residents and fellows who were performing surgery in an animal laboratory or using high-fidelity manikins. The evaluators had no previous affiliation with the residents and fellows and did not know their year of training. INTERVENTIONS One- and 2-page versions of an objective structured assessment of technical skills (OSATS) assessment instrument composed of global and a task-specific surgical items were used to evaluate surgical performance. RESULTS Fifty-two evaluations were completed by 17 attending evaluators. The instrument agreement for the 2-page assessment was 71.4% when measured as a binary variable (ie, competent vs not competent) (κ = 0.38; P = .08). Evaluation as a continuous variable revealed a 42.9% percentage agreement (κ = 0.18; P = .14). The intraclass correlation was 0.53, considered substantial/good interrater reliability (69% reliable). For the 1-page instrument, agreement was 77.4% when measured as a binary variable (κ = 0.53, P = .0015). Agreement when evaluated as a continuous measure was 71.0% (κ = 0.54, P formative feedback on operational competency.

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

Component reliability analysis for development of component reliability DB of Korean standard NPPs

International Nuclear Information System (INIS)

Choi, S. Y.; Han, S. H.; Kim, S. H.

2002-01-01

The reliability data of Korean NPP that reflects the plant specific characteristics is necessary for PSA and Risk Informed Application. We have performed a project to develop the component reliability DB and calculate the component reliability such as failure rate and unavailability. We have collected the component operation data and failure/repair data of Korean standard NPPs. We have analyzed failure data by developing a data analysis method which incorporates the domestic data situation. And then we have compared the reliability results with the generic data for the foreign NPPs

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

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

Initial operation and performance of the PDX neutral-beam injection system

International Nuclear Information System (INIS)

Kugel, H.W.; Eubank, H.P.; Kozub, T.A.; Rossmassler, J.E.; Schilling, G.; van Halle, A.; Williams, M.D.

1982-01-01

In 1981, the joint ORNL/PPPL PDX neutral beam heating project succeeded in reliably injecting 7.2 MW of D 0 into the PDX plasma, at nearly perpendicular angles, and achieved ion temperatures up to 6.5 keV. The expeditious achievement of this result was due to the thorough conditioning and qualification of the PDX neutral beam ion sources at ORNL prior to delivery coupled with several field design changes and improvements in the injection system made at PPPL as a result of neutral beam operating experience with the PLT tokamak. It has been found that the operation of high power neutral beam injection systems in a tokamak-neutral beam environment requires procedures and performance different from those required for development operation on test stands. In this paper, we review the installatin of the PDX neutral beam injection system, and its operation and performance during the initial high power plasma heating experiments with the PDX tokamak

Performance and Reliability of Bonded Interfaces for High-temperature Packaging: Annual Progress Report

Energy Technology Data Exchange (ETDEWEB)

DeVoto, Douglas J. [National Renewable Energy Laboratory (NREL), Golden, CO (United States)

2017-10-19

As maximum device temperatures approach 200 °Celsius, continuous operation, sintered silver materials promise to maintain bonds at these high temperatures without excessive degradation rates. A detailed characterization of the thermal performance and reliability of sintered silver materials and processes has been initiated for the next year. Future steps in crack modeling include efforts to simulate crack propagation directly using the extended finite element method (X-FEM), a numerical technique that uses the partition of unity method for modeling discontinuities such as cracks in a system.

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)

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

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)

The cognitive environment simulation as a tool for modeling human performance and reliability

International Nuclear Information System (INIS)

Woods, D.D.; Pople, H. Jr.; Roth, E.M.

1990-01-01

The US Nuclear Regulatory Commission is sponsoring a research program to develop improved methods to model the cognitive behavior of nuclear power plant (NPP) personnel. Under this program, a tool for simulating how people form intentions to act in NPP emergency situations was developed using artificial intelligence (AI) techniques. This tool is called Cognitive Environment Simulation (CES). The Cognitive Reliability Assessment Technique (or CREATE) was also developed to specify how CBS can be used to enhance the measurement of the human contribution to risk in probabilistic risk assessment (PRA) studies. The next step in the research program was to evaluate the modeling tool and the method for using the tool for Human Reliability Analysis (HRA) in PRAs. Three evaluation activities were conducted. First, a panel of highly distinguished experts in cognitive modeling, AI, PRA and HRA provided a technical review of the simulation development work. Second, based on panel recommendations, CES was exercised on a family of steam generator tube rupture incidents where empirical data on operator performance already existed. Third, a workshop with HRA practitioners was held to analyze a worked example of the CREATE method to evaluate the role of CES/CREATE in HRA. The results of all three evaluations indicate that CES/CREATE represents a promising approach to modeling operator intention formation during emergency operations

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...

Simulation-based Assessment to Reliably Identify Key Resident Performance Attributes.

Science.gov (United States)

Blum, Richard H; Muret-Wagstaff, Sharon L; Boulet, John R; Cooper, Jeffrey B; Petrusa, Emil R; Baker, Keith H; Davidyuk, Galina; Dearden, Jennifer L; Feinstein, David M; Jones, Stephanie B; Kimball, William R; Mitchell, John D; Nadelberg, Robert L; Wiser, Sarah H; Albrecht, Meredith A; Anastasi, Amanda K; Bose, Ruma R; Chang, Laura Y; Culley, Deborah J; Fisher, Lauren J; Grover, Meera; Klainer, Suzanne B; Kveraga, Rikante; Martel, Jeffrey P; McKenna, Shannon S; Minehart, Rebecca D; Mitchell, John D; Mountjoy, Jeremi R; Pawlowski, John B; Pilon, Robert N; Shook, Douglas C; Silver, David A; Warfield, Carol A; Zaleski, Katherine L

2018-04-01

Obtaining reliable and valid information on resident performance is critical to patient safety and training program improvement. The goals were to characterize important anesthesia resident performance gaps that are not typically evaluated, and to further validate scores from a multiscenario simulation-based assessment. Seven high-fidelity scenarios reflecting core anesthesiology skills were administered to 51 first-year residents (CA-1s) and 16 third-year residents (CA-3s) from three residency programs. Twenty trained attending anesthesiologists rated resident performances using a seven-point behaviorally anchored rating scale for five domains: (1) formulate a clear plan, (2) modify the plan under changing conditions, (3) communicate effectively, (4) identify performance improvement opportunities, and (5) recognize limits. A second rater assessed 10% of encounters. Scores and variances for each domain, each scenario, and the total were compared. Low domain ratings (1, 2) were examined in detail. Interrater agreement was 0.76; reliability of the seven-scenario assessment was r = 0.70. CA-3s had a significantly higher average total score (4.9 ± 1.1 vs. 4.6 ± 1.1, P = 0.01, effect size = 0.33). CA-3s significantly outscored CA-1s for five of seven scenarios and domains 1, 2, and 3. CA-1s had a significantly higher proportion of worrisome ratings than CA-3s (chi-square = 24.1, P < 0.01, effect size = 1.50). Ninety-eight percent of residents rated the simulations more educational than an average day in the operating room. Sensitivity of the assessment to CA-1 versus CA-3 performance differences for most scenarios and domains supports validity. No differences, by experience level, were detected for two domains associated with reflective practice. Smaller score variances for CA-3s likely reflect a training effect; however, worrisome performance scores for both CA-1s and CA-3s suggest room for improvement.

French power system reliability report 2008

International Nuclear Information System (INIS)

Tesseron, J.M.

2009-06-01

The reliability of the French power system was fully under control in 2008, despite the power outage in the eastern part of the Provence-Alpes-Cote d'Azur region on November 3, which had been dreaded for several years, since it had not been possible to set up a structurally adequate network. Pursuant to a consultation meeting, the reinforcement solution proposed by RTE was approved by the Minister of Energy, boding well for greater reliability in future. Based on the observations presented in this 2008 Report, RTE's Power System Reliability Audit Mission considers that no new recommendations are needed beyond those expressed in previous reliability reports and during reliability audits. The publication of this yearly report is in keeping with RTE's goal to promote the follow-up over time of the evolution of reliability in its various aspects. RTE thus aims to contribute to the development of reliability culture, by encouraging an improved assessment by the different players (both RTE and network users) of the role they play in building reliability, and by advocating the taking into account of reliability and benchmarking in the European organisations of Transmission System Operators. Contents: 1 - Brief overview of the evolution of the internal and external environment; 2 - Operating situations encountered: climatic conditions, supply / demand balance management, operation of interconnections, management of internal congestion, contingencies affecting the transmission facilities; 3 - Evolution of the reliability reference guide: external reference guide: directives, laws, decrees, etc, ETSO, UCTE, ENTSO-E, contracting contributing to reliability, RTE internal reference guide; 4 - Evolution of measures contributing to reliability in the equipment field: intrinsic performances of components (generating sets, protection systems, operation PLC's, instrumentation and control, automatic frequency and voltage controls, transmission facilities, control systems, load

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.)

PyOperators: Operators and solvers for high-performance computing

Science.gov (United States)

Chanial, P.; Barbey, N.

2012-12-01

PyOperators is a publicly available library that provides basic operators and solvers for small-to-very large inverse problems ({http://pchanial.github.com/pyoperators}). It forms the backbone of the package PySimulators, which implements specific operators to construct an instrument model and means to conveniently represent a map, a timeline or a time-dependent observation ({http://pchanial.github.com/pysimulators}). Both are part of the Tamasis (Tools for Advanced Map-making, Analysis and SImulations of Submillimeter surveys) toolbox, aiming at providing versatile, reliable, easy-to-use, and optimal map-making tools for Herschel and future generation of sub-mm instruments. The project is a collaboration between 4 institutes (ESO Garching, IAS Orsay, CEA Saclay, Univ. Leiden).

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

The impact of laboratory quality assurance standards on laboratory operational performance

Directory of Open Access Journals (Sweden)

E Ratseou

2014-01-01

Full Text Available It has become a trend for companies to implement and be certified to various quality management systems so as to improve consistency, reliability, and quality of product delivery to customers. The most common quality management systems adopted are the ISO 9000 series of standards for manufacturing and services related organisations, with ISO 17025 and Good Laboratory Practices (GLP standards adopted specifically by laboratories as quality assurance initiatives. There are various reports on the impact of the ISO 9000 series on organisational performance but no studies or reports have been done on the performance of laboratory standards. Therefore this article reports on a study conducted to investigate the impact of ISO 17025 and GLP on the operational performance of both commercial and non-commercial laboratories. A qualitative research study was conducted to examine the impact standards on the aspects of health and safety, supplier selection and performance, human resources, customer satisfaction and profitability of the laboratory. The data collected suggest that there is no difference in laboratory operational performance with or without the standards. In other words it appears that the basic fundamental requirements inherent with laboratories are sufficient to perform both operationally and optimally. This leads to the view that standards are implemented as a customer requirement and not as an operational requirement.

MYRRHA cryogenic system study on performances and reliability requirements

International Nuclear Information System (INIS)

Junquera, T.; Chevalier, N.R.; Thermeau, J.P.; Medeiros Romao, L.; Vandeplassche, D.

2015-01-01

A precise evaluation of the cryogenic requirements for accelerator-driven system such as the MYRRHA project has been performed. In particular, operation temperature, thermal losses, and required cryogenic power have been evaluated. A preliminary architecture of the cryogenic system including all its major components, as well as the principles for the cryogenic fluids distribution has been proposed. A detailed study on the reliability aspects has also been initiated. This study is based on the reliability of large cryogenic systems used for accelerators like HERA, LHC or SNS Linac. The requirements to guarantee good cryogenic system availability can be summarised as follows: 1) Mean Time Between Maintenance (MTBM) should be > 8 000 hours; 2) Valves, heat exchangers and turbines are particularly sensitive elements to impurities (dust, oil, gases), improvements are necessary to keep a minimal level in these components; 3) Redundancy studies for all elements containing moving/vibrating parts (turbines, compressors, including their respective bearings and seal shafts) are necessary; 4) Periodic maintenance is mandatory: oil checks, control of screw compressors every 10.000-15.000 hours, vibration surveillance programme, etc; 5) Special control and maintenance of utilities equipment (supply of cooling water, compressed air and electrical supply) is necessary; 6) Periodic vacuum checks to identify leakage appearance such as insulation vacuum of transfer lines and distribution boxes are necessary; 7) Easily exchangeable cold compressors are required

World class performance: the outage/operating cycle continuum

Energy Technology Data Exchange (ETDEWEB)

Remphal, M. [Ontario Power Generation, Darlington, Ontario (Canada)

2011-07-01

It's all about Performance! Predictable and sustainable high performance is the key to public and stakeholder confidence in the nuclear industry. Why? Because nuclear is unique and safe, reliable operation each and every day is required to keep public trust. What better way to demonstrate this predictability than in breaker to breaker operating runs? Delivering on what was promised is the essence of our OPG accountability model: 'Say it, Do it'. This presentation is drawn from practical experience gained during the most recent planned maintenance outages at Darlington Nuclear. Key elements for outage success that will be discussed include; Human Performance: Ensuring each action is deliberate and executed right the first time; Continuous Learning: Recent examples demonstrating how drawing from lessons learned and operating experience worldwide can dramatically improve outage performance; Teamwork and Partnership: Recognizing our industry is too complex for a single; individual or organization to run on its own; Scope Selection: Darlington currently has an industry leading 0.5% Forced Loss Rate (FLR). If right work is selected and executed at the right time then ultimately the plant speaks and it shows up in low FLR and high Nuclear Performance Index; Planning: Ask and anticipate what can go wrong, what options exist and then pre-decide what path you would take. Some practical tools will be provided which have been recently used to plan out surprises; Oversight: An outage left to run its own course will have a surprise outcome. Strong management oversight is required to meet the goals of outage execution. Tips on how to improve communication and accountability will be discussed. Trust is built on confidence and confidence is built on sustainable performance. World class sustainable performance requires using all the tools available. This discussion will provide insight on these very tools. (author)

World class performance: the outage/operating cycle continuum

International Nuclear Information System (INIS)

Remphal, M.

2011-01-01

It's all about Performance! Predictable and sustainable high performance is the key to public and stakeholder confidence in the nuclear industry. Why? Because nuclear is unique and safe, reliable operation each and every day is required to keep public trust. What better way to demonstrate this predictability than in breaker to breaker operating runs? Delivering on what was promised is the essence of our OPG accountability model: 'Say it, Do it'. This presentation is drawn from practical experience gained during the most recent planned maintenance outages at Darlington Nuclear. Key elements for outage success that will be discussed include; Human Performance: Ensuring each action is deliberate and executed right the first time; Continuous Learning: Recent examples demonstrating how drawing from lessons learned and operating experience worldwide can dramatically improve outage performance; Teamwork and Partnership: Recognizing our industry is too complex for a single; individual or organization to run on its own; Scope Selection: Darlington currently has an industry leading 0.5% Forced Loss Rate (FLR). If right work is selected and executed at the right time then ultimately the plant speaks and it shows up in low FLR and high Nuclear Performance Index; Planning: Ask and anticipate what can go wrong, what options exist and then pre-decide what path you would take. Some practical tools will be provided which have been recently used to plan out surprises; Oversight: An outage left to run its own course will have a surprise outcome. Strong management oversight is required to meet the goals of outage execution. Tips on how to improve communication and accountability will be discussed. Trust is built on confidence and confidence is built on sustainable performance. World class sustainable performance requires using all the tools available. This discussion will provide insight on these very tools. (author)

Dynamic performance of self-operated three-way valve used in a hybrid air conditioner

International Nuclear Information System (INIS)

Zhang, Penglei; Zhou, Dehai; Shi, Wenxing; Li, Xianting; Wang, Baolong

2014-01-01

A hybrid air conditioner combining a thermosyphon cycle with a vapor compression refrigeration cycle has a large energy saving potential compared with a common air conditioner for spaces requiring year-round cooling. The performance of the switch between the vapor compression mode and the thermosyphon mode largely impacts the safety and reliability of hybrid air conditioners. Therefore, a self-operated three-way valve is proposed. A thermodynamic model and a kinetic model are developed in this paper to evaluate the dynamic performance of the switch valve. The effects of the spring force constant, compressor discharging volume, fit clearance and piston length on the dynamic performance of the switch valve are analyzed. In conclusion, the proposed self-operated three-way valve can realize the switch operation accurately. - Highlights: •A self-operated three-way valve is proposed for hybrid air conditioners. •The thermodynamic model and kinetic model of the self-operated three-way valve are developed. •The validity of models is verified by experiments. •Effects of four main design parameters on the operating performance of the valve are researched

Fuzzy inference system for evaluating and improving nuclear power plant operating performance

International Nuclear Information System (INIS)

Guimaraes, Antonio Cesar F.; Lapa, Celso Marcelo Franklin

2003-01-01

This paper presents a fuzzy inference system (FIS) as an approach to estimate Nuclear Power Plant (NPP) performance indicators. The performance indicators for this study are the energy availability factor (EAF) and the planned (PUF) and unplanned unavailability factor (UUF). These indicators are obtained from a non analytical combination among the same operational parameters. Such parameters are, for example, environment impacts, industrial safety, radiological protection, safety indicators, scram rate, thermal efficiency, and fuel reliability. This approach uses the concept of a pure fuzzy logic system where the fuzzy rule base consists of a collection of fuzzy IF-THEN rules. The fuzzy inference engine uses these fuzzy IF-THEN rules to determine a mapping from fuzzy sets in the input universe of discourse to fuzzy sets in the output universe of discourse based on fuzzy logic principles. The results demonstrated the potential of the fuzzy inference to generate a knowledge basis that correlate operations occurrences and NPP performance. The inference system became possible the development of the sensitivity studies, future operational condition previsions and may support the eventual corrections on operation of the plant

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

MEMS Reliability: Infrastructure, Test Structures, Experiments, and Failure Modes

Energy Technology Data Exchange (ETDEWEB)

TANNER,DANELLE M.; SMITH,NORMAN F.; IRWIN,LLOYD W.; EATON,WILLIAM P.; HELGESEN,KAREN SUE; CLEMENT,J. JOSEPH; MILLER,WILLIAM M.; MILLER,SAMUEL L.; DUGGER,MICHAEL T.; WALRAVEN,JEREMY A.; PETERSON,KENNETH A.

2000-01-01

The burgeoning new technology of Micro-Electro-Mechanical Systems (MEMS) shows great promise in the weapons arena. We can now conceive of micro-gyros, micro-surety systems, and micro-navigators that are extremely small and inexpensive. Do we want to use this new technology in critical applications such as nuclear weapons? This question drove us to understand the reliability and failure mechanisms of silicon surface-micromachined MEMS. Development of a testing infrastructure was a crucial step to perform reliability experiments on MEMS devices and will be reported here. In addition, reliability test structures have been designed and characterized. Many experiments were performed to investigate failure modes and specifically those in different environments (humidity, temperature, shock, vibration, and storage). A predictive reliability model for wear of rubbing surfaces in microengines was developed. The root causes of failure for operating and non-operating MEMS are discussed. The major failure mechanism for operating MEMS was wear of the polysilicon rubbing surfaces. Reliability design rules for future MEMS devices are established.

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

International Nuclear Information System (INIS)

1979-01-01

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

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

OpenAIRE

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

2013-01-01

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

Charging performance of automotive batteries-An underestimated factor influencing lifetime and reliable battery operation

Science.gov (United States)

Sauer, Dirk Uwe; Karden, Eckhard; Fricke, Birger; Blanke, Holger; Thele, Marc; Bohlen, Oliver; Schiffer, Julia; Gerschler, Jochen Bernhard; Kaiser, Rudi

Dynamic charge acceptance and charge acceptance under constant voltage charging conditions are for two reasons essential for lead-acid battery operation: energy efficiency in applications with limited charging time (e.g. PV systems or regenerative braking in vehicles) and avoidance of accelerated ageing due to sulphation. Laboratory tests often use charge regimes which are beneficial for the battery life, but which differ significantly from the operating conditions in the field. Lead-acid batteries in applications with limited charging time and partial-state-of-charge operation are rarely fully charged due to their limited charge acceptance. Therefore, they suffer from sulphation and early capacity loss. However, when appropriate charging strategies are applied most of the lost capacity and thus performance for the user may be recovered. The paper presents several aspects of charging regimes and charge acceptance. Theoretical and experimental investigations show that temperature is the most critical parameter. Full charging within short times can be achieved only at elevated temperatures. A strong dependency of the charge acceptance during charging pulses on the pre-treatment of the battery can be observed, which is not yet fully understood. But these effects have a significant impact on the fuel efficiency of micro-hybrid electric vehicles.

Reliability of the Fermilab Antiproton Source

International Nuclear Information System (INIS)

Harms, E. Jr.

1993-05-01

This paper reports on the reliability of the Fermilab Antiproton source since it began operation in 1985. Reliability of the complex as a whole as well as subsystem performance is summarized. Also discussed is the trending done to determine causes of significant machine downtime and actions taken to reduce the incidence of failure. Finally, results of a study to detect previously unidentified reliability limitations are presented

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.

Deep Space Network equipment performance, reliability, and operations management information system

Science.gov (United States)

Cooper, T.; Lin, J.; Chatillon, M.

2002-01-01

The Deep Space Mission System (DSMS) Operations Program Office and the DeepSpace Network (DSN) facilities utilize the Discrepancy Reporting Management System (DRMS) to collect, process, communicate and manage data discrepancies, equipment resets, physical equipment status, and to maintain an internal Station Log. A collaborative effort development between JPL and the Canberra Deep Space Communication Complex delivered a system to support DSN Operations.

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.)

The role of human performance in safe operation of complex plants

International Nuclear Information System (INIS)

Preda, Irina Aida; Lazar, Roxana Elena; Croitoru, Cornelia

1999-01-01

According to statistics, about 20-30% from the failures occurring in plants are caused directly or indirectly by human errors. Furthermore, it was established that 10-15 percents of the global failures are related to the human errors. These are mainly due to the wrong actions, maintenance errors, and misinterpretation of instruments. The human performance is influenced by: professional ability, complexity and danger of the plant, experience in the same working place, level of skills, events in personal and/or professional life, discipline, social ambience and somatic health. The human performances assessment in the probabilistic safety assessment offers the possibility of evaluation for human contribution to the events sequences outcome. A human error may be recovered before the unwanted consequences had been occurred on system. This paper presents the possibilities to use the probabilistic methods (event tree, fault tree) to identify the solution for human reliability improvement in order to minimise the risk in industrial plant operation. Also, are defined the human error types and their causes and the 'decision tree method' is presented as technique in our analyses for human reliability assessment. The exemplification of human error analysis method was achieved based on operation data for Valcea heavy water pilot plant. (authors)

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)

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.

A Fast Optimization Method for Reliability and Performance of Cloud Services Composition Application

Directory of Open Access Journals (Sweden)

Zhao Wu

2013-01-01

Full Text Available At present the cloud computing is one of the newest trends of distributed computation, which is propelling another important revolution of software industry. The cloud services composition is one of the key techniques in software development. The optimization for reliability and performance of cloud services composition application, which is a typical stochastic optimization problem, is confronted with severe challenges due to its randomness and long transaction, as well as the characteristics of the cloud computing resources such as openness and dynamic. The traditional reliability and performance optimization techniques, for example, Markov model and state space analysis and so forth, have some defects such as being too time consuming and easy to cause state space explosion and unsatisfied the assumptions of component execution independence. To overcome these defects, we propose a fast optimization method for reliability and performance of cloud services composition application based on universal generating function and genetic algorithm in this paper. At first, a reliability and performance model for cloud service composition application based on the multiple state system theory is presented. Then the reliability and performance definition based on universal generating function is proposed. Based on this, a fast reliability and performance optimization algorithm is presented. In the end, the illustrative examples are given.

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

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

Reliability and Validity of the Turkish Version of the Job Performance Scale Instrument.

Science.gov (United States)

Harmanci Seren, Arzu Kader; Tuna, Rujnan; Eskin Bacaksiz, Feride

2018-02-01

Objective measurement of the job performance of nursing staff using valid and reliable instruments is important in the evaluation of healthcare quality. A current, valid, and reliable instrument that specifically measures the performance of nurses is required for this purpose. The aim of this study was to determine the validity and reliability of the Turkish version of the Job Performance Instrument. This study used a methodological design and a sample of 240 nurses working at different units in four hospitals in Istanbul, Turkey. A descriptive data form, the Job Performance Scale, and the Employee Performance Scale were used to collect data. Data were analyzed using IBM SPSS Statistics Version 21.0 and LISREL Version 8.51. On the basis of the data analysis, the instrument was revised. Some items were deleted, and subscales were combined. The Turkish version of the Job Performance Instrument was determined to be valid and reliable to measure the performance of nurses. The instrument is suitable for evaluating current nursing roles.

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.

Human reliability analysis of performing tasks in plants based on fuzzy integral

International Nuclear Information System (INIS)

Washio, Takashi; Kitamura, Yutaka; Takahashi, Hideaki

1991-01-01

The effective improvement of the human working conditions in nuclear power plants might be a solution for the enhancement of the operation safety. The human reliability analysis (HRA) gives a methodological basis of the improvement based on the evaluation of human reliability under various working conditions. This study investigates some difficulties of the human reliability analysis using conventional linear models and recent fuzzy integral models, and provides some solutions to the difficulties. The following practical features of the provided methods are confirmed in comparison with the conventional methods: (1) Applicability to various types of tasks (2) Capability of evaluating complicated dependencies among working condition factors (3) A priori human reliability evaluation based on a systematic task analysis of human action processes (4) A conversion scheme to probability from indices representing human reliability. (author)

GNF2 Operating Experience

International Nuclear Information System (INIS)

Schardt, John

2007-01-01

GNF's latest generation fuel product, GNF2, is designed to deliver improved nuclear efficiency, higher bundle and cycle energy capability, and more operational flexibility. But along with high performance, our customers face a growing need for absolute fuel reliability. This is driven by a general sense in the industry that LWR fuel reliability has plateaued. Too many plants are operating with fuel leakers, and the impact on plant operations and operator focus is unacceptable. The industry has responded by implementing an INPO-coordinated program aimed at achieving leaker-free reliability by 2010. One focus area of the program is the relationship between fuel performance (i.e., duty) and reliability. The industry recognizes that the right balance between performance and problem-free fuel reliability is critical. In the development of GNF2, GNF understood the requirement for a balanced solution and utilized a product development and introduction strategy that specifically addressed reliability: evolutionary design features supported by an extensive experience base; thoroughly tested components; and defense-in-depth mitigation of all identified failure mechanisms. The final proof test that the balance has been achieved is the application of the design, initially through lead use assemblies (LUAs), in a variety of plants that reflect the diversity of the BWR fleet. Regular detailed surveillance of these bundles provides the verification that the proper balance between performance and reliability has been achieved. GNF currently has GNF2 lead use assemblies operating in five plants. Included are plants that have implemented extended power up-rates, plants on one and two-year operating cycles, and plants with and without NobleChem TM and zinc injection. The leading plant has undergone three pool-side inspections outages to date. This paper reviews the actions taken to insure GNF2's reliability, and the lead use assembly surveillance data accumulated to date to validate

Analysis of the operational performance and efficiency characteristic for photovoltaic system in Hong Kong

International Nuclear Information System (INIS)

Li, Danny H.W.; Cheung, Gary H.W.; Lam, Joseph C.

2005-01-01

The applications of photovoltaic (PV) systems have become more widespread in both developed and developing countries. The most critical exercise in designing a PV system is the determination of the optimum size of the solar panel and the battery capacity to meet the load demand with acceptable reliability. The amount of power generated by a PV system strongly depends on the availability of solar insolation at the required location. Also, the efficiency of a PV system is influenced considerably by a number of climatic variables, such as solar irradiance availability and ambient temperature. The technical information is provided for standard test conditions that may never occur in practice. Reliable knowledge of the performance of PV systems under actual operating conditions is essential for correct product selection and accurate performance prediction. This paper investigates the operational performance and efficiency characteristic of a small PV system installed at the City University of Hong Kong. The solar data and the power generated by the PV system are systematically recorded and analysed. The findings provide technical data in different months for designers and engineers to assess and size PV systems

Photovoltaic Reliability Performance Model v 2.0

Energy Technology Data Exchange (ETDEWEB)

2016-12-16

PV-RPM is intended to address more “real world” situations by coupling a photovoltaic system performance model with a reliability model so that inverters, modules, combiner boxes, etc. can experience failures and be repaired (or left unrepaired). The model can also include other effects, such as module output degradation over time or disruptions such as electrical grid outages. In addition, PV-RPM is a dynamic probabilistic model that can be used to run many realizations (i.e., possible future outcomes) of a system’s performance using probability distributions to represent uncertain parameter inputs.

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

Flash memories economic principles of performance, cost and reliability optimization

CERN Document Server

Richter, Detlev

2014-01-01

The subject of this book is to introduce a model-based quantitative performance indicator methodology applicable for performance, cost and reliability optimization of non-volatile memories. The complex example of flash memories is used to introduce and apply the methodology. It has been developed by the author based on an industrial 2-bit to 4-bit per cell flash development project. For the first time, design and cost aspects of 3D integration of flash memory are treated in this book. Cell, array, performance and reliability effects of flash memories are introduced and analyzed. Key performance parameters are derived to handle the flash complexity. A performance and array memory model is developed and a set of performance indicators characterizing architecture, cost and durability is defined.   Flash memories are selected to apply the Performance Indicator Methodology to quantify design and technology innovation. A graphical representation based on trend lines is introduced to support a requirement based pr...

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

Bayesian approach in the power electric systems study of reliability ...

African Journals Online (AJOL)

Keywords: Reliability - Power System - Bayes Theorem - Weibull Model - Probability. ... ensure a series of estimated parameter (failure rate, mean time to failure, function .... only on random variable r.v. describing the operating conditions: ..... Multivariate performance reliability prediction in real-time, Reliability Engineering.

Human Error Probabilites (HEPs) for generic tasks and Performance Shaping Factors (PSFs) selected for railway operations

DEFF Research Database (Denmark)

Thommesen, Jacob; Andersen, Henning Boje

This report describes an HRA (Human Reliability Assessment) of six generic tasks and four Perfor-mance Shaping Factors (PSFs) targeted at railway operations commissioned by Banedanmark. The selection and characterization of generic tasks and PSFs are elaborated by DTU Management in close...

Microgrid Design Analysis Using Technology Management Optimization and the Performance Reliability Model

Energy Technology Data Exchange (ETDEWEB)

Stamp, Jason E. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Eddy, John P. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Jensen, Richard P. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Munoz-Ramos, Karina [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

2016-01-01

Microgrids are a focus of localized energy production that support resiliency, security, local con- trol, and increased access to renewable resources (among other potential benefits). The Smart Power Infrastructure Demonstration for Energy Reliability and Security (SPIDERS) Joint Capa- bility Technology Demonstration (JCTD) program between the Department of Defense (DOD), Department of Energy (DOE), and Department of Homeland Security (DHS) resulted in the pre- liminary design and deployment of three microgrids at military installations. This paper is focused on the analysis process and supporting software used to determine optimal designs for energy surety microgrids (ESMs) in the SPIDERS project. There are two key pieces of software, an ex- isting software application developed by Sandia National Laboratories (SNL) called Technology Management Optimization (TMO) and a new simulation developed for SPIDERS called the per- formance reliability model (PRM). TMO is a decision support tool that performs multi-objective optimization over a mixed discrete/continuous search space for which the performance measures are unrestricted in form. The PRM is able to statistically quantify the performance and reliability of a microgrid operating in islanded mode (disconnected from any utility power source). Together, these two software applications were used as part of the ESM process to generate the preliminary designs presented by SNL-led DOE team to the DOD. Acknowledgements Sandia National Laboratories and the SPIDERS technical team would like to acknowledge the following for help in the project: * Mike Hightower, who has been the key driving force for Energy Surety Microgrids * Juan Torres and Abbas Akhil, who developed the concept of microgrids for military instal- lations * Merrill Smith, U.S. Department of Energy SPIDERS Program Manager * Ross Roley and Rich Trundy from U.S. Pacific Command * Bill Waugaman and Bill Beary from U.S. Northern Command * Tarek Abdallah, Melanie

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.

High-Performance Operating Systems

DEFF Research Database (Denmark)

Sharp, Robin

1999-01-01

Notes prepared for the DTU course 49421 "High Performance Operating Systems". The notes deal with quantitative and qualitative techniques for use in the design and evaluation of operating systems in computer systems for which performance is an important parameter, such as real-time applications......, communication systems and multimedia systems....

Reliable and Valid Assessment of Clinical Bronchoscopy Performance

DEFF Research Database (Denmark)

Konge, Lars; Larsen, Klaus Richter; Clementsen, Paul

2012-01-01

: The interrater reliability was high, with Cronbach's a = 0.86. Assessment of 3 bronchoscopies by a single rater had a generalizability coefficient of 0.84. The correlation between experience and performance was good (Pearson correlation = 0.76). There were significant differences between the groups for all...

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

Energy Technology Data Exchange (ETDEWEB)

Jeffrey C. JOe; Ronald L. Boring

2014-06-01

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

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.

Silicon Carbide (SiC) Device and Module Reliability, Performance of a Loop Heat Pipe Subjected to a Phase-Coupled Heat Input to an Acceleration Field

Science.gov (United States)

2016-05-01

AFRL-RQ-WP-TR-2016-0108 SILICON CARBIDE (SiC) DEVICE AND MODULE RELIABILITY Performance of a Loop Heat Pipe Subjected to a Phase-Coupled...CARBIDE (SiC) DEVICE AND MODULE RELIABILITY Performance of a Loop Heat Pipe Subjected to a Phase-Coupled Heat Input to an Acceleration Field 5a...Shukla, K., “Thermo-fluid dynamics of Loop Heat Pipe Operation,” International Communications in Heat and Mass Transfer , Vol. 35, No. 8, 2008, pp

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.

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)

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

Impacts of Contingency Reserve on Nodal Price and Nodal Reliability Risk in Deregulated Power Systems

DEFF Research Database (Denmark)

Zhao, Qian; Wang, Peng; Goel, Lalit

2013-01-01

The deregulation of power systems allows customers to participate in power market operation. In deregulated power systems, nodal price and nodal reliability are adopted to represent locational operation cost and reliability performance. Since contingency reserve (CR) plays an important role...... in reliable operation, the CR commitment should be considered in operational reliability analysis. In this paper, a CR model based on customer reliability requirements has been formulated and integrated into power market settlement. A two-step market clearing process has been proposed to determine generation...

Performance analysis of Supply Chain Management with Supply Chain Operation reference model

Science.gov (United States)

Hasibuan, Abdurrozzaq; Arfah, Mahrani; Parinduri, Luthfi; Hernawati, Tri; Suliawati; Harahap, Bonar; Rahmah Sibuea, Siti; Krianto Sulaiman, Oris; purwadi, Adi

2018-04-01

This research was conducted at PT. Shamrock Manufacturing Corpora, the company is required to think creatively to implement competition strategy by producing goods/services that are more qualified, cheaper. Therefore, it is necessary to measure the performance of Supply Chain Management in order to improve the competitiveness. Therefore, the company is required to optimize its production output to meet the export quality standard. This research begins with the creation of initial dimensions based on Supply Chain Management process, ie Plan, Source, Make, Delivery, and Return with hierarchy based on Supply Chain Reference Operation that is Reliability, Responsiveness, Agility, Cost, and Asset. Key Performance Indicator identification becomes a benchmark in performance measurement whereas Snorm De Boer normalization serves to equalize Key Performance Indicator value. Analiytical Hierarchy Process is done to assist in determining priority criteria. Measurement of Supply Chain Management performance at PT. Shamrock Manufacturing Corpora produces SC. Responsiveness (0.649) has higher weight (priority) than other alternatives. The result of performance analysis using Supply Chain Reference Operation model of Supply Chain Management performance at PT. Shamrock Manufacturing Corpora looks good because its monitoring system between 50-100 is good.

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

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

An integrated reliability management system for nuclear power plants

International Nuclear Information System (INIS)

Kimura, T.; Shimokawa, H.; Matsushima, H.

1998-01-01

The responsibility in the nuclear field of the Government, utilities and manufactures has increased in the past years due to the need of stable operation and great reliability of nuclear power plants. The need to improve the reliability is not only for the new plants but also for those now running. So, several measures have been taken to improve reliability. In particular, the plant manufactures have developed a reliability management system for each phase (planning, construction, maintenance and operation) and these have been integrated as a unified system. This integrated reliability management system for nuclear power plants contains information about plant performance, failures and incidents which have occurred in the plants. (author)

Developing safety performance functions incorporating reliability-based risk measures.

Science.gov (United States)

Ibrahim, Shewkar El-Bassiouni; Sayed, Tarek

2011-11-01

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

The reliability of integrated gasification combined cycle (IGCC) power generation units

Energy Technology Data Exchange (ETDEWEB)

Higman, C.; DellaVilla, S.; Steele, B. [Syngas Consultants Ltd. (United Kingdom)

2006-07-01

This paper presents two interlinked projects aimed at supporting the improvement of integrated gasification combined cycle (IGCC) reliability. The one project comprises the extension of SPS's existing ORAP (Operational Reliability Analysis Program) reliability, availability and maintainability (RAM) tracking technology from its existing base in natural gas open and combined cycle operations into IGCC. The other project is using the extended ORAP database to evaluate performance data from existing plants. The initial work has concentrated on evaluating public domain data on the performance of gasification based power and chemical plants. This is being followed up by plant interviews in some 20 plants to verify and expand the database on current performance. 23 refs., 8 figs., 2 tabs.

Performance of High Temperature Operational Amplifier, Type LM2904WH, under Extreme Temperatures

Science.gov (United States)

Patterson, Richard; Hammoud, Ahmad; Elbuluk, Malik

2008-01-01

Operation of electronic parts and circuits under extreme temperatures is anticipated in NASA space exploration missions as well as terrestrial applications. Exposure of electronics to extreme temperatures and wide-range thermal swings greatly affects their performance via induced changes in the semiconductor material properties, packaging and interconnects, or due to incompatibility issues between interfaces that result from thermal expansion/contraction mismatch. Electronics that are designed to withstand operation and perform efficiently in extreme temperatures would mitigate risks for failure due to thermal stresses and, therefore, improve system reliability. In addition, they contribute to reducing system size and weight, simplifying its design, and reducing development cost through the elimination of otherwise required thermal control elements for proper ambient operation. A large DC voltage gain (100 dB) operational amplifier with a maximum junction temperature of 150 C was recently introduced by STMicroelectronics [1]. This LM2904WH chip comes in a plastic package and is designed specifically for automotive and industrial control systems. It operates from a single power supply over a wide range of voltages, and it consists of two independent, high gain, internally frequency compensated operational amplifiers. Table I shows some of the device manufacturer s specifications.

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)

The role of human performance in the safety complex plants' operation

International Nuclear Information System (INIS)

Preda, Irina Aida; Lazar, Roxana Elena; Croitoru, Cornelia

1999-01-01

According to statistics, about 20-30% from the failures occurred in the plants are caused directly or indirectly by human errors. Furthermore, it was established that 10-15% of the global failures are related with the human errors. These are mainly due to the wrong actions, maintenance errors, and misinterpretation of instruments. The human performance is influenced by: professional ability, complexity and danger to the plant experience in the working place, level of skills, events in personal and/or professional life, discipline, social ambience, somatic health. The human performances' assessment in the probabilistic safety assessment offers the possibility of evaluation of human contribution to the events sequences outcome. Not all the human errors have impact on the system. A human error may be recovered before the unwanted consequences had been occurred on system. This paper presents the possibilities to use the probabilistic method (event tree, fault tree) to identify the solutions for human reliability improved in order to minimize the risk in industrial plants' operation. Also, the human error types and their causes are defined and the 'decision tree method' as technique in our analysis for human reliability assessment is presented. The exemplification of human error analysis method was achieved based on operation data for Valcea Heavy Water Pilot Plant. As initiating event for the accident state 'the steam supply interruption' event has been considered. The human errors' contribution was analysed for the accident sequence with the worst consequences. (authors)

Cognitive Performance in Operational Environments

Science.gov (United States)

Russo, Michael; McGhee, James; Friedler, Edna; Thomas, Maria

2005-01-01

Optimal cognition during complex and sustained operations is a critical component for success in current and future military operations. "Cognitive Performance, Judgment, and Decision-making" (CPJD) is a newly organized U.S. Army Medical Research and Materiel Command research program focused on sustaining operational effectiveness of Future Force Warriors by developing paradigms through which militarily-relevant, higher-order cognitive performance, judgment, and decision-making can be assessed and sustained in individuals, small teams, and leaders of network-centric fighting units. CPJD evaluates the impact of stressors intrinsic to military operational environments (e.g., sleep deprivation, workload, fatigue, temperature extremes, altitude, environmental/physiological disruption) on military performance, evaluates noninvasive automated methods for monitoring and predicting cognitive performance, and investigates pharmaceutical strategies (e.g., stimulant countermeasures, hypnotics) to mitigate performance decrements. This manuscript describes the CPJD program, discusses the metrics utilized to relate militarily applied research findings to academic research, and discusses how the simulated combat capabilities of a synthetic battle laboratory may facilitate future cognitive performance research.

Performers and performance : how to investigate the contribution of the operational network to operational performance

NARCIS (Netherlands)

Wijngaard, J.; Vries, J. de; Nauta, A.

2006-01-01

Purpose This paper seeks to explore the question of how to investigate the contribution of the operational network (comprising sales service, logistics, planning, production, etc.) to operational performance. In doing so, the paper aims to link concepts from organisational and social psychology to

Performers and performance : How to investigate the contribution of the operational network to operational performance

NARCIS (Netherlands)

Wijngaard, J.; de Vries, J.; Nauta, Aukje

2006-01-01

Purpose - This paper seeks to explore the question of how to investigate the contribution of the operational network (comprising sales service, logistics, planning, production, etc.) to operational performance. In doing so, the paper aims to link concepts from organisational and social psychology to

Predicting space telerobotic operator training performance from human spatial ability assessment

Science.gov (United States)

Liu, Andrew M.; Oman, Charles M.; Galvan, Raquel; Natapoff, Alan

2013-11-01

Our goal was to determine whether existing tests of spatial ability can predict an astronaut's qualification test performance after robotic training. Because training astronauts to be qualified robotics operators is so long and expensive, NASA is interested in tools that can predict robotics performance before training begins. Currently, the Astronaut Office does not have a validated tool to predict robotics ability as part of its astronaut selection or training process. Commonly used tests of human spatial ability may provide such a tool to predict robotics ability. We tested the spatial ability of 50 active astronauts who had completed at least one robotics training course, then used logistic regression models to analyze the correlation between spatial ability test scores and the astronauts' performance in their evaluation test at the end of the training course. The fit of the logistic function to our data is statistically significant for several spatial tests. However, the prediction performance of the logistic model depends on the criterion threshold assumed. To clarify the critical selection issues, we show how the probability of correct classification vs. misclassification varies as a function of the mental rotation test criterion level. Since the costs of misclassification are low, the logistic models of spatial ability and robotic performance are reliable enough only to be used to customize regular and remedial training. We suggest several changes in tracking performance throughout robotics training that could improve the range and reliability of predictive models.

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....

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.

Sequential decision reliability concept and failure rate assessment

International Nuclear Information System (INIS)

Ciftcioglu, O.

1990-11-01

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

Quantification of the reliability of personnel actions from the evaluation of actual German operational experience. Final report; Quantifizierung der Zuverlaessigkeit von Personalhandlungen durch Auswertung der aktuellen deutschen Betriebserfahrung. Abschlussbericht

Energy Technology Data Exchange (ETDEWEB)

Preischl, W.; Fassmann, W.

2013-07-15

The results and their uncertainty bounds of PSA studies are considerably impacted by the assessment of human reliability. But the amount of available, generic data is not sufficient to evaluate all human actions considered in a modern PSA study adequately. Further the data are not sufficiently validated and rely as well as the proposed uncertainty bounds on expert judgement. This research project as well as the preceding project /GRS 10/ validated data recommended by the German PSA Guidelines and enlarged the amount of available data. The findings may contribute to an update of the German PSA Guidelines. In a first step of the project information about reportable events in German nuclear power plants with observed human errors (event reports, expert statements, technical documents, interviews and plant walk downs with subject matter experts from the plants) were analysed. The investigation resulted in 67 samples describing personal activities, performance conditions, the number of observed errors and the number of action performance. In a second step a new methodology was developed and applied in a pilot plant. The objective was to identify undoubtedly error free safety relevant actions, their performance conditions, and frequency as well as to prove and demonstrate that probabilistic data can be derived from that operational experience (OE). The application in the pilot plant resulted in 18 ''error free'' samples characterizing human reliability. All available samples were evaluated by use of the method of Bayes. That commonly accepted methodology was applied in order to derive probabilistic data based on samples taken from operational experience. A thorough analysis of the obtained results shows that both data sources (OE reportable events, OE with undoubtedly error free action performance) provide data with comparable quality and validity. At the end of the research project the following products are available. - Methods to select samples

Operating experience and performance at Narora Atomic Power Station

International Nuclear Information System (INIS)

Mittal, Subhash; Gupta, J.P.

1998-01-01

Narora Atomic Power Station consists of two units of 220 MWe capacity each. These are Pressurized Heavy Water Reactors, fuelled by natural uranium, moderated and cooled by heavy water. The Station is owned by Nuclear Power Corporation of India Ltd., which is responsible for design, construction, commissioning, and operation of all nuclear power stations in the country. NAPS was the first opportunity to apply operating experiences in design, keeping in view the evolving safety and seismicity requirements, ease of maintenance, inservice inspection needs, improved construction ability and standardization. Both the units of NAPS are having improved safety standards of current international levels. All the equipment are indigenous with improved quality and reliability. The first unit of the station went critical in March 1989 and synchronized to the grid in July 1989. The second units followed with its criticality in October 1991 and synchronization in January 1992. Considering the initial stabilizing period, the performance of both units of NAPS has progressively improved over the years. The annual capacity factor for NAPS - 1 was 90.01% and for NAPS - 2 was 89.01% for the financial year 1997-1998. This paper presents an analysis of the performance during the last three years and measures taken to improve it. The stated enhanced performance could be achieved by improvement in human performance by training/re-training, scrupulous monitoring and review of equipment/systems, institution of adequate procedure and ensuring their adherence. (authors)

Correlation Relationship of Performance Shaping Factors (PSFs) for Human Reliability Analysis

Energy Technology Data Exchange (ETDEWEB)

Bheka, M. Khumalo; Kim, Jonghyun [KEPCO International Nuclear Graduate School, Ulsan (Korea, Republic of)

2014-10-15

At TMI-2, operators permitted thousands of gallons of water to escape from the reactor plant before realizing that the coolant pumps were behaving abnormally. The coolant pumps were then turned off, which in turn led to the destruction of the reactor itself as cooling was completely lost within the core. Human also plays a role in many aspects of complex systems e.g. in design and manufacture of hardware, interface between human and system and also in maintaining such systems as well as for coping with unusual events that place the NPP system at a risk. This is why human reliability analysis (HRA) - an aspect of risk assessments which systematically identifies and analyzes the causes and consequences of human decisions and actions - is important in nuclear power plant operations. It either upgrades or degrades human performance; therefore it has an impact on the possibility of error. These PSFs can be used in various HRA methods to estimate Human Error Probabilities (HEPs). There are many current HRA methods who propose sets of PSFs for normal operation mode of NPP. Some of these PSFs in the sets have some degree of dependency and overlap. Overlapping PSFs introduce error in HEP evaluations due to the fact that some elements are counted more than once in data; this skews the relationship amongst PSF and masks the way that the elements interact to affect performance. This study uses a causal model that represents dependencies and relationships amongst PSFs for HEP evaluation during normal NPP operational states. The model is built taking into consideration the dependencies among PSFs and thus eliminating overlap. The use of an interdependent model of PSFs is expected to produce more accurate HEPs compared to other current methods. PSF sets produced in this study can be further used as nodes (variables) and directed arcs (causal influence between nodes) in HEP evaluation methods such as Bayesian belief (BN) networks. This study was done to estimate the relationships

Basic research on human reliability in nuclear power plants

International Nuclear Information System (INIS)

Zhang Li; Deng Zhiliang

1996-10-01

Human reliability in nuclear power plants is one of key factors in nuclear safety and economic operation. According to cognitive science, behaviour theory and ergonomic and on the bases of human cognitive behaviour characteristics, performance shaping factors, human error mechanisms and organization management, the project systematically studied the human reliability in nuclear power plant systems, established the basic theory and methods for analyzing human factor accidents and suggested feasible approaches and countermeasures for precaution against human factor accidents and improving human reliability. The achievement has been applied in operation departments, management departments and scientific research institutions of nuclear power, and has produced guiding significance and practical value to design, operation and management in nuclear power plants. (11 refs.)

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)

A criterion of the performance of thermometric systems of high metrological reliability

International Nuclear Information System (INIS)

Sal'nikov, N.L.; Filimonov, E.V.

1995-01-01

Monitoring temperature regimes is an important part of ensuring the operational safety of a nuclear power plant. Therefore, high standards are imposed upon the reliability of the primary information on the heat field of the object obtained from different sensors, and it is urgent to develop methods of evaluating the metrological reliability of these sensors. THe main sources of thermometric information at nuclear power plants are contact temperature sensors, the most widely used of these being thermoelectric converters (TEC) and thermal resistance converters (TRC)

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.

Effect of Sensors on the Reliability and Control Performance of Power Circuits in the Web of Things (WoT

Directory of Open Access Journals (Sweden)

Sungwoo Bae

2016-09-01

Full Text Available In order to realize a true WoT environment, a reliable power circuit is required to ensure interconnections among a range of WoT devices. This paper presents research on sensors and their effects on the reliability and response characteristics of power circuits in WoT devices. The presented research can be used in various power circuit applications, such as energy harvesting interfaces, photovoltaic systems, and battery management systems for the WoT devices. As power circuits rely on the feedback from voltage/current sensors, the system performance is likely to be affected by the sensor failure rates, sensor dynamic characteristics, and their interface circuits. This study investigated how the operational availability of the power circuits is affected by the sensor failure rates by performing a quantitative reliability analysis. In the analysis process, this paper also includes the effects of various reconstruction and estimation techniques used in power processing circuits (e.g., energy harvesting circuits and photovoltaic systems. This paper also reports how the transient control performance of power circuits is affected by sensor interface circuits. With the frequency domain stability analysis and circuit simulation, it was verified that the interface circuit dynamics may affect the transient response characteristics of power circuits. The verification results in this paper showed that the reliability and control performance of the power circuits can be affected by the sensor types, fault tolerant approaches against sensor failures, and the response characteristics of the sensor interfaces. The analysis results were also verified by experiments using a power circuit prototype.

Validity and reliability of tests determining performance-related components of wheelchair basketball

NARCIS (Netherlands)

De Groot, Sonja; Balvers, Inge J. M.; Kouwenhoven, Sanne M.; Janssen, Thomas W. J.

2012-01-01

The purpose of this study was to investigate the reliability and validity of wheelchair basketball field tests. Nineteen wheelchair basketball players performed 10 test items twice to determine the reliability. The validity of the tests was assessed by relating the scores to the players'

Validity and reliability of tests determining performance-related components of wheelchair basketball

NARCIS (Netherlands)

de Groot, Sonja; Balvers, Inge J.M.; Kouwenhoven, Sanne M.; Janssen, Thomas W.J.

The purpose of this study was to investigate the reliability and validity of wheelchair basketball field tests. Nineteen wheelchair basketball players performed 10 test items twice to determine the reliability. The validity of the tests was assessed by relating the scores to the players'

Supply chain reliability modelling

Directory of Open Access Journals (Sweden)

Eugen Zaitsev

2012-03-01

Full Text Available Background: Today it is virtually impossible to operate alone on the international level in the logistics business. This promotes the establishment and development of new integrated business entities - logistic operators. However, such cooperation within a supply chain creates also many problems related to the supply chain reliability as well as the optimization of the supplies planning. The aim of this paper was to develop and formulate the mathematical model and algorithms to find the optimum plan of supplies by using economic criterion and the model for the probability evaluating of non-failure operation of supply chain. Methods: The mathematical model and algorithms to find the optimum plan of supplies were developed and formulated by using economic criterion and the model for the probability evaluating of non-failure operation of supply chain. Results and conclusions: The problem of ensuring failure-free performance of goods supply channel analyzed in the paper is characteristic of distributed network systems that make active use of business process outsourcing technologies. The complex planning problem occurring in such systems that requires taking into account the consumer's requirements for failure-free performance in terms of supply volumes and correctness can be reduced to a relatively simple linear programming problem through logical analysis of the structures. The sequence of the operations, which should be taken into account during the process of the supply planning with the supplier's functional reliability, was presented.

An integrated approach to human reliability analysis -- decision analytic dynamic reliability model

International Nuclear Information System (INIS)

Holmberg, J.; Hukki, K.; Norros, L.; Pulkkinen, U.; Pyy, P.

1999-01-01

The reliability of human operators in process control is sensitive to the context. In many contemporary human reliability analysis (HRA) methods, this is not sufficiently taken into account. The aim of this article is that integration between probabilistic and psychological approaches in human reliability should be attempted. This is achieved first, by adopting such methods that adequately reflect the essential features of the process control activity, and secondly, by carrying out an interactive HRA process. Description of the activity context, probabilistic modeling, and psychological analysis form an iterative interdisciplinary sequence of analysis in which the results of one sub-task maybe input to another. The analysis of the context is carried out first with the help of a common set of conceptual tools. The resulting descriptions of the context promote the probabilistic modeling, through which new results regarding the probabilistic dynamics can be achieved. These can be incorporated in the context descriptions used as reference in the psychological analysis of actual performance. The results also provide new knowledge of the constraints of activity, by providing information of the premises of the operator's actions. Finally, the stochastic marked point process model gives a tool, by which psychological methodology may be interpreted and utilized for reliability analysis

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

Daya Bay Nuclear Power Station equipment reliability management system innovation

International Nuclear Information System (INIS)

Gao Ligang; Wang Zongjun

2006-01-01

Daya Bay Nuclear Power Station has achieved good performance since its commercial operation in 1994. The equipment reliability management system that features Daya Bay characteristics has been established through constant technology introduction, digestion and innovation. It is also based on the success of operational system, equipment maintenance system and technical support system. The system lays a solid foundation for the long-term safe operation of power station. This article emphasizes on the innovation part of equipment reliability management system in Daya Bay. (authors)

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)

Safe and economic performance of nuclear power plant. Operation through meticulous Q/A programmes - a german example

International Nuclear Information System (INIS)

Schenk, H.J.

1989-01-01

Safe and reliable operation of a nuclear power plant over its life time of 40 to 60 years is the essential condition for an economic performance. This goal can be achieved by a qualified responsible staff realizing a high quality of operation and by maintaining high quality and technical standards in the plant in accordance with the status of science and technology. Quality assurance procedures have to verify this in detail, in close contact with the work to be performed. In this presentation I would like to describe our approach in Philippsburg to cope with this task

RELIABILITY OF ANKLE-FOOT MORPHOLOGY, MOBILITY, STRENGTH, AND MOTOR PERFORMANCE MEASURES.

Science.gov (United States)

Fraser, John J; Koldenhoven, Rachel M; Saliba, Susan A; Hertel, Jay

2017-12-01

Assessment of foot posture, morphology, intersegmental mobility, strength and motor control of the ankle-foot complex are commonly used clinically, but measurement properties of many assessments are unclear. To determine test-retest and inter-rater reliability, standard error of measurement, and minimal detectable change of morphology, joint excursion and play, strength, and motor control of the ankle-foot complex. Reliability study. 24 healthy, recreationally-active young adults without history of ankle-foot injury were assessed by two clinicians on two occasions, three to ten days apart. Measurement properties were assessed for foot morphology (foot posture index, total and truncated length, width, arch height), joint excursion (weight-bearing dorsiflexion, rearfoot and hallux goniometry, forefoot inclinometry, 1 st metatarsal displacement) and joint play, strength (handheld dynamometry), and motor control rating during intrinsic foot muscle (IFM) exercises. Clinician order was randomized using a Latin Square. The clinicians performed independent examinations and did not confer on the findings for the duration of the study. Test-retest and inter-tester reliability and agreement was assessed using intraclass correlation coefficients (ICC 2,k ) and weighted kappa ( K w ). Test-retest reliability ICC were as follows: morphology: .80-1.00, joint excursion: .58-.97, joint play: -.67-.84, strength: .67-.92, IFM motor rating: K W -.01-.71. Inter-rater reliability ICC were as follows: morphology: .81-1.00, joint excursion: .32-.97, joint play: -1.06-1.00, strength: .53-.90, and IFM motor rating: K w .02-.56. Measures of ankle-foot posture, morphology, joint excursion, and strength demonstrated fair to excellent test-retest and inter-rater reliability. Test-retest reliability for rating of perceived difficulty and motor performance was good to excellent for short-foot, toe-spread-out, and hallux exercises and poor to fair for lesser toe extension. Joint play measures had

Reliability of thermal-hydraulic passive safety systems

International Nuclear Information System (INIS)

D'Auria, F.; Araneo, D.; Pierro, F.; Galassi, G.

2014-01-01

The scholar will be informed of reliability concepts applied to passive system adopted for nuclear reactors. Namely, for classical components and systems the failure concept is associated with malfunction of breaking of hardware. In the case of passive systems the failure is associated with phenomena. A method for studying the reliability of passive systems is discussed and is applied. The paper deals with the description of the REPAS (Reliability Evaluation of Passive Safety System) methodology developed by University of Pisa (UNIPI) and with results from its application. The general objective of the REPAS methodology is to characterize the performance of a passive system in order to increase the confidence toward its operation and to compare the performances of active and passive systems and the performances of different passive systems

RELIABILITY OF THE DYNAMIC OCCUPATIONAL THERAPY COGNITIVE ASSESSMENT FOR CHILDREN (DOTCA-CH: THAI VERSION OF ORIENTATION, SPATIAL PERCEPTION, AND THINKING OPERATIONS SUBTESTS

Directory of Open Access Journals (Sweden)

Suchitporn Lersilp

2014-06-01

Full Text Available The Dynamic Occupational Therapy Cognitive Assessment for Children (DOTCA-Ch is a tool for finding out about cognitive problems in school-aged children. However, the DOTCA-Ch was developed in English for Western children. For this reason, it’s not appropriate for Thai children because of the differences of culture and language. The objectives of this study were aimed at translating the DOTCA-Ch in Orientation, Spatial Perception, and Thinking Operations subtests to a Thai version with a World Health Organization back-translation process, and to examine its internal consistency, inter-rater reliability and test-retest reliability. The participants consisted of 38 intellectually impaired and learning disabled individuals between the ages of 6–12. Results from this study revealed high internal consistency in the Orientation subtest (α=.83 Spatial Perception subtest (α=.82 and Thinking Operations subtest (α=.82, high inter-rater reliability in the Orientation subtest (ICC =.83, Spatial Perception subtest (ICC =.84 and Thinking Operations subtest (ICC =.74 and high test-retest reliability in the Orientation subtest (ICC =.84 Spatial Perception subtest (ICC =.86 and Thinking Operations subtest (ICC =.85. These results indicate that the Thai version of the DOTCA-Ch in Orientation, Spatial Perception, and Thinking Operations subtests  might be used as an appropriate assessment tool for Thai children, based on psychometric evidence including internal consistency, inter-rater reliability and test-retest reliability. However, additional study of other psychometric properties, including, predictive validity, concurrent reliability, and inter-rater reliability during the mediation process of this assessment tool needs to be carried out.

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)

Forward lunge as a functional performance test in ACL deficient subjects: test-retest reliability

DEFF Research Database (Denmark)

Alkjaer, Tine; Henriksen, Marius; Dyhre-Poulsen, Poul

2009-01-01

The forward lunge movement may be used as a functional performance test of anterior cruciate ligament (ACL) deficient and reconstructed subjects. The purposes were 1) to determine the test-retest reliability of a forward lunge in healthy subjects and 2) to determine the required numbers...... of repetitions necessary to yield satisfactory reliability. Nineteen healthy subjects performed four trials of a forward lunge on two different days. The movement time, impulses of the ground reaction forces (IFz, IFy), knee joint kinematics and dynamics during the forward lunge were calculated. The relative...... reliability was determined by calculation of Intraclass Correlation Coefficients (ICC). The IFz, IFy and the positive work of the knee extensors showed excellent reliability (ICC >0.75). All other variables demonstrated acceptable reliability (0.4>ICCreliability increased when more than...

Levels of Management Commitment: A Moderator the Structural Relationships among Critical Success Factors of TQM, World-Class Performance in Operations, and Company Financial Performance

Directory of Open Access Journals (Sweden)

Wakhid Slamet Ciptono

2012-01-01

Full Text Available This study investigates the moderating impacts of the three levels of management commitment (top, middle, and low levels on the structural relationships among the constructs— six critical success factors of TQM (quality improvement program, supervisory leadership, supplier involvement, management commitment, training to improve products/services, cross-functional relationships; world-class performance in operations (world-class company practices, operational excellence practices, company non-financial performance; and company financial performance. It uses a sample of 1,332 managers in 140 strategic business units (SBUs within 49 oil and gas companies in Indonesia. The empirical results indicate that the goodness-of-fit of the unconstrained model is much better than that of the constrained model, and this is an indicative that the three level of management moderates the structural relationships among the constructs. Those are, three levels of management act as a moderator variable between critical success factors of TQM, world-class company practices, operational excellence practices, company non-financial performance, and company financial performance. Results further reveal that world-class performances in operations (world-class company practices, operational excellence practices, and company non-financial performance were positively mediated the impact of critical success factors of TQM on company financial performance. Results also point out that five of six critical success factors of TQM positively associated with world-class company practices and operational excellence practices under the three levels of management (top, middle, low. World-class company practices and operational excellence practices have direct and significant effects on company non-financial performance (productivity, operational reliability. Furthermore, empirical results suggest that there is a positive and significant relationship between company non

Design of thermoelectric modules for both mechanical reliability and performance using FE simulation

DEFF Research Database (Denmark)

Sarhadi, Ali; Bjørk, Rasmus; Pryds, Nini

for these two objectives. The current study deals with FE simulation of the TE modules to optimize their geometrical dimension in terms of mechanical reliability and performance. First, FE simulation of a TE module consisting of bismuth telluride alloys is carried out and the induced thermal stresses, output......, the geometrical dimensions of the TE elements for both mechanical reliability and performance are optimized to obtain a compromise design. The present work provides a basis for optimizing the TE modules in terms of their life time and performance.......Thermo-mechanical modeling of the TE modules provides an efficient tool for assessing the mechanical strength of the modules against the induced thermal stresses and subsequently optimizing them in terms of the mechanical reliability. However, the design of TE modules in terms of mechanical...

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

Self-assessment of human performance errors in nuclear operations

International Nuclear Information System (INIS)

Chambliss, K.V.

1996-01-01

One of the most important approaches to improving nuclear safety is to have an effective self-assessment process in place, whose cornerstone is the identification and improvement of human performance errors. Experience has shown that significant events usually have had precursors of human performance errors. If these precursors are left uncorrected or not understood, the symptoms recur and result in unanticipated events of greater safety significance. The Institute of Nuclear Power Operations (INPO) has been championing the cause of promoting excellence in human performance in the nuclear industry. INPO's report, open-quotes Excellence in Human Performance,close quotes emphasizes the importance of several factors that play a role in human performance. They include individual, supervisory, and organizational behaviors; real-time feedback that results in specific behavior to produce safe and reliable performance; and proactive measures that remove obstacles from excellent human performance. Zack Pate, chief executive officer and president of INPO, in his report, open-quotes The Control Room,close quotes provides an excellent discussion of serious events in the nuclear industry since 1994 and compares them with the results from a recent study by the National Transportation Safety Board of airline accidents in the 12-yr period from 1978 to 1990 to draw some common themes that relate to human performance issues in the control room

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.

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

Science-based HRA: experimental comparison of operator performance to IDAC (Information-Decision-Action Crew) simulations

Energy Technology Data Exchange (ETDEWEB)

Shirley, Rachel [The Ohio State Univ., Columbus, OH (United States); Smidts, Carol [The Ohio State Univ., Columbus, OH (United States); Boring, Ronald [Idaho National Lab. (INL), Idaho Falls, ID (United States); Li, Yuandan [Univ. of Maryland, College Park, MD (United States); Mosleh, Ali [Univ. of Maryland, College Park, MD (United States)

2015-02-01

Information-Decision-Action Crew (IDAC) operator model simulations of a Steam Generator Tube Rupture are compared to student operator performance in studies conducted in the Ohio State University’s Nuclear Power Plant Simulator Facility. This study is presented as a prototype for conducting simulator studies to validate key aspects of Human Reliability Analysis (HRA) methods. Seven student operator crews are compared to simulation results for crews designed to demonstrate three different decision-making strategies. The IDAC model used in the simulations is modified slightly to capture novice behavior rather that expert operators. Operator actions and scenario pacing are compared. A preliminary review of available performance shaping factors (PSFs) is presented. After the scenario in the NPP Simulator Facility, student operators review a video of the scenario and evaluate six PSFs at pre-determined points in the scenario. This provides a dynamic record of the PSFs experienced by the OSU student operators. In this preliminary analysis, Time Constraint Load (TCL) calculated in the IDAC simulations is compared to TCL reported by student operators. We identify potential modifications to the IDAC model to develop an “IDAC Student Operator Model.” This analysis provides insights into how similar experiments could be conducted using expert operators to improve the fidelity of IDAC simulations.

Reliability and performance evaluation of stainless and mild steel ...

African Journals Online (AJOL)

Reliability and performance of stainless and mild steel products in methanolic and aqueous sodium chloride media have been investigated. Weight-loss and pre-exposure methods were used. There was a higher rate of weight-loss of mild steels and stainless steels in 1% HCl methanolic solution than in aqueous NaCl ...

Development of reliability-based safety enhancement technology

International Nuclear Information System (INIS)

Kim, Kil Yoo; Han, Sang Hoon; Jang, Seung Cherl

2002-04-01

This project aims to develop critical technologies and the necessary reliability DB for maximizing the economics in the NPP operation with keeping the safety using the information of the risk (or reliability). For the research goal, firstly the four critical technologies(Risk Informed Tech. Spec. Optimization, Risk Informed Inservice Testing, On-line Maintenance, Maintenance Rule) for RIR and A have been developed. Secondly, KIND (Korea Information System for Nuclear Reliability Data) has been developed. Using KIND, YGN 3,4 and UCN 3,4 component reliability DB have been established. A reactor trip history DB for all NPP in Korea also has been developed and analyzed. Finally, a detailed reliability analysis of RPS/ESFAS for KNSP has been performed. With the result of the analysis, the sensitivity analysis also has been performed to optimize the AOT/STI of tech. spec. A statistical analysis procedure and computer code have been developed for the set point drift analysis

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

Development of web-based reliability data base platform

International Nuclear Information System (INIS)

Hwang, Seok Won; Lee, Chang Ju; Sung, Key Yong

2004-01-01

Probabilistic safety assessment (PSA) is a systematic technique which estimates the degree of risk impacts to the public due to an accident scenario. Estimating the occurrence frequencies and consequences of potential scenarios requires a thorough analysis of the accident details and all fundamental parameters. The robustness of PSA to check weaknesses in a design and operation will allow a better informed and balanced decision to be reached. The fundamental parameters for PSA, such as the component failure rates, should be estimated under the condition of steady collection of the evidence throughout the operational period. However, since any single plant data does not sufficiently enough to provide an adequate PSA result, in actual, the whole operating data was commonly used to estimate the reliability parameters for the same type of components. The reliability data of any component type consists of two categories; the generic that is based on the operating experiences of whole plants, and the plant-specific that is based on the operation of a specific plant of interest. The generic data is highly essential for new or recently-built nuclear power plants (NPPs). Generally, the reliability data base may be categorized into the component reliability, initiating event frequencies, human performance, and so on. Among these data, the component reliability seems a key element because it has the most abundant population. Therefore, the component reliability data is essential for taking a part in the quantification of accident sequences because it becomes an input of various basic events which consists of the fault tree

Issues in cognitive reliability

International Nuclear Information System (INIS)

Woods, D.D.; Hitchler, M.J.; Rumancik, J.A.

1984-01-01

This chapter examines some problems in current methods to assess reactor operator reliability at cognitive tasks and discusses new approaches to solve these problems. The two types of human failures are errors in the execution of an intention and errors in the formation/selection of an intention. Topics considered include the types of description, error correction, cognitive performance and response time, the speed-accuracy tradeoff function, function based task analysis, and cognitive task analysis. One problem of human reliability analysis (HRA) techniques in general is the question of what are the units of behavior whose reliability are to be determined. A second problem for HRA is that people often detect and correct their errors. The use of function based analysis, which maps the problem space for plant control, is recommended

Proceedings of the 1998 Photovoltaic Performance and Reliability Workshop

International Nuclear Information System (INIS)

Kroposki, B.

1998-01-01

This proceedings is the compilation of all papers presented at the 11th PV Performance and Reliability Workshop held at the Doubletree Hotel in Cocoa Beach, Florida, on November 3-5, 1998. The workshop was hosted by the Florida Solar Energy Center. This year's workshop included presentations from 29 speakers and had 110 attendees

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

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.

Methodology for the identification of the factors that can influence the performance of operators of nuclear power plants control room under emergency situations

International Nuclear Information System (INIS)

Paiva, Bernardo Spitz; Santos, Isaac J.A. Luquetti

2009-01-01

In order to minimize the human errors of the operators in a nuclear power plan control room, during emergency situations, it has to be considered the factors which affect the human performance. Work situations adequately projected, compatible with the necessities, capacities and human limitations, taking into consideration the factors which affect the operator performance . This paper aims to develop a methodology for identification of the factors affecting the operator performance under emergency situation, using the aspects defined by the human reliability analysis focusing the judgment done by specialists

Mechanical development for reliable reactor components

International Nuclear Information System (INIS)

Ross-Ross, P.A.; Metcalfe, R.

1983-09-01

The CANDU reactor has achieved worldwide distinction because of its reliable performance. To achieve this, special attention was given to the reliability and maintainability of components in the heavy water circuits. Development programs were initiated early in the history of the CANDU reactor to improve the effectiveness of pump seals, valves, and static seals because of unacceptable performance of the commercial equipment then available. As a result, pump seals with a five year life now appear achievable, and valves and static seals are no longer a significant concern in CANDU reactors. Increasing effort is being given remotely operated tools and fabrication systems for radioactive environments

Comprehensive Performance Nutrition for Special Operations Forces.

Science.gov (United States)

Daigle, Karen A; Logan, Christi M; Kotwal, Russ S

2015-01-01

Special Operations Forces (SOF) training, combat, and contingency operations are unique and demanding. Performance nutrition within the Department of Defense has emphasized that nutrition is relative to factors related to the desired outcome, which includes successful performance of mentally and physically demanding operations and missions of tactical and strategic importance, as well as nonoperational assignments. Discussed are operational, nonoperational, and patient categories that require different nutrition strategies to facilitate category-specific performance outcomes. Also presented are 10 major guidelines for a SOF comprehensive performance nutrition program, practical nutrition recommendations for Special Operators and medical providers, as well as resources for dietary supplement evaluation. Foundational health concepts, medical treatment, and task-specific performance factors should be considered when developing and systematically implementing a comprehensive SOF performance nutrition program. When tailored to organizational requirements, SOF unit- and culture-specific nutrition education and services can optimize individual Special Operator performance, overall unit readiness, and ultimately, mission success. 2015.

Assessing the reliability of skilled performance

International Nuclear Information System (INIS)

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

1996-01-01

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

Fiber Access Networks: Reliability Analysis and Swedish Broadband Market

Science.gov (United States)

Wosinska, Lena; Chen, Jiajia; Larsen, Claus Popp

Fiber access network architectures such as active optical networks (AONs) and passive optical networks (PONs) have been developed to support the growing bandwidth demand. Whereas particularly Swedish operators prefer AON, this may not be the case for operators in other countries. The choice depends on a combination of technical requirements, practical constraints, business models, and cost. Due to the increasing importance of reliable access to the network services, connection availability is becoming one of the most crucial issues for access networks, which should be reflected in the network owner's architecture decision. In many cases protection against failures is realized by adding backup resources. However, there is a trade off between the cost of protection and the level of service reliability since improving reliability performance by duplication of network resources (and capital expenditures CAPEX) may be too expensive. In this paper we present the evolution of fiber access networks and compare reliability performance in relation to investment and management cost for some representative cases. We consider both standard and novel architectures for deployment in both sparsely and densely populated areas. While some recent works focused on PON protection schemes with reduced CAPEX the current and future effort should be put on minimizing the operational expenditures (OPEX) during the access network lifetime.

Experience of CR and RCCA operation in Ukrainian WWER-1000: Aspects of reliability, safety and economic efficiency

International Nuclear Information System (INIS)

Afanasyev, A.

2000-01-01

The next topics are represented in the paper: A brief history of WWER-1000 control rod (CR) and WWER-1000 rod cluster control assembly (RCCA) design; Evolution of WWER-1000 CR manufacturing technology and design; Experience of RCCA operation; Lifetime extension of WWER-1000 boron carbide CR; WWER-1000 reactor core operation problems due to partial RCCA insertion; Designing and licensing procedures and first operational experience of WWER-1000 RCCA (CR) with a combined absorber 'boron carbide-hafnium' and a chromium-nickel alloy cladding. The main conclusions are: Fuel assembly (FA) bow is the main reason of partial RCCA insertion during reactor core operation. However, the use of the RCCA and its driver bar with increased dead load, alongside with other measures, allow to reduce the probability of incomplete RCCA insertion; The materials used in CRs of RCCA in existing reactor operating modes have been working reliably; The use of hafnium under an appropriate price policy can give certain economic advantages for the Ukrainian NPPs, however, additional research is needed in order to confirm the specific CR physical characteristics and reliability. (author)

Reliability modeling of degradation of products with multiple performance characteristics based on gamma processes

International Nuclear Information System (INIS)

Pan Zhengqiang; Balakrishnan, Narayanaswamy

2011-01-01

Many highly reliable products usually have complex structure, with their reliability being evaluated by two or more performance characteristics. In certain physical situations, the degradation of these performance characteristics would be always positive and strictly increasing. In such a case, the gamma process is usually considered as a degradation process due to its independent and non-negative increments properties. In this paper, we suppose that a product has two dependent performance characteristics and that their degradation can be modeled by gamma processes. For such a bivariate degradation involving two performance characteristics, we propose to use a bivariate Birnbaum-Saunders distribution and its marginal distributions to approximate the reliability function. Inferential method for the corresponding model parameters is then developed. Finally, for an illustration of the proposed model and method, a numerical example about fatigue cracks is discussed and some computational results are presented.

PV Systems Reliability Final Technical Report.

Energy Technology Data Exchange (ETDEWEB)

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

2015-12-01

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

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.

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...

Component fragility data base for reliability and probability studies

International Nuclear Information System (INIS)

Bandyopadhyay, K.; Hofmayer, C.; Kassier, M.; Pepper, S.

1989-01-01

Safety-related equipment in a nuclear plant plays a vital role in its proper operation and control, and failure of such equipment due to an earthquake may pose a risk to the safe operation of the plant. Therefore, in order to assess the overall reliability of a plant, the reliability of performance of the equipment should be studied first. The success of a reliability or a probability study depends to a great extent on the data base. To meet this demand, Brookhaven National Laboratory (BNL) has formed a test data base relating the seismic capacity of equipment specimens to the earthquake levels. Subsequently, the test data have been analyzed for use in reliability and probability studies. This paper describes the data base and discusses the analysis methods. The final results that can be directly used in plant reliability and probability studies are also presented in this paper

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)

TH-F-209-01: Pitfalls: Reliability and Performance of Diagnostic X-Ray Sources

International Nuclear Information System (INIS)

Behling, R.

2016-01-01

Purpose: Performance and reliability of medical X-ray tubes for imaging are crucial from an ethical, clinical and economic perspective. This lecture will deliver insight into the aspects to consider during the decision making process to invest in X-ray imaging equipment. Outdated metric still hampers realistic product comparison. It is time to change this and to comply with latest standards, which consider current technology. Failure modes and ways to avoid down-time of the equipment shall be discussed. In view of the increasing number of interventional procedures and the hazards associated with ionizing radiation, toxic contrast agents, and the combination thereof, the aspect of system reliability is of paramount importance. Methods: A comprehensive picture of trends for different modalities (CT, angiography, general radiology) has been drawn and led to the development of novel X-ray tube technology. Results: Recent X-ray tubes feature enhanced reliability and unprecedented performance. Relevant metrics for product comparison still have to be implemented in practice. Conclusion: The speed of scientific and industrial development of new diagnostic and therapeutic X-ray sources remains tremendous. Still, users suffer from gaps between desire and reality in day-to-day diagnostic routine. X-ray sources are still limiting cutting-edge medical procedures. Side-effects of wear and tear, limitations of the clinical work flow, costs, the characteristics of the X-ray spectrum and others topics need to be further addressed. New applications and modalities, like detection-based color-resolved X-ray and phase-contrast / dark-field imaging will impact the course of new developments of X-ray sources. Learning Objectives: Understand the basic requirements on medical diagnostic X-ray sources per modality Learn to select the optimal equipment employing state-of-the-art metric Know causes of failures, depending on the way X-ray sources are operated Understand methods to remediate

TH-F-209-00: Pitfalls: Reliability and Performance of Diagnostic X-Ray Sources

International Nuclear Information System (INIS)

2016-01-01

Purpose: Performance and reliability of medical X-ray tubes for imaging are crucial from an ethical, clinical and economic perspective. This lecture will deliver insight into the aspects to consider during the decision making process to invest in X-ray imaging equipment. Outdated metric still hampers realistic product comparison. It is time to change this and to comply with latest standards, which consider current technology. Failure modes and ways to avoid down-time of the equipment shall be discussed. In view of the increasing number of interventional procedures and the hazards associated with ionizing radiation, toxic contrast agents, and the combination thereof, the aspect of system reliability is of paramount importance. Methods: A comprehensive picture of trends for different modalities (CT, angiography, general radiology) has been drawn and led to the development of novel X-ray tube technology. Results: Recent X-ray tubes feature enhanced reliability and unprecedented performance. Relevant metrics for product comparison still have to be implemented in practice. Conclusion: The speed of scientific and industrial development of new diagnostic and therapeutic X-ray sources remains tremendous. Still, users suffer from gaps between desire and reality in day-to-day diagnostic routine. X-ray sources are still limiting cutting-edge medical procedures. Side-effects of wear and tear, limitations of the clinical work flow, costs, the characteristics of the X-ray spectrum and others topics need to be further addressed. New applications and modalities, like detection-based color-resolved X-ray and phase-contrast / dark-field imaging will impact the course of new developments of X-ray sources. Learning Objectives: Understand the basic requirements on medical diagnostic X-ray sources per modality Learn to select the optimal equipment employing state-of-the-art metric Know causes of failures, depending on the way X-ray sources are operated Understand methods to remediate

TH-F-209-01: Pitfalls: Reliability and Performance of Diagnostic X-Ray Sources

Energy Technology Data Exchange (ETDEWEB)

Behling, R. [Philips Medical Systems DMC GmbH (United States)

2016-06-15

Purpose: Performance and reliability of medical X-ray tubes for imaging are crucial from an ethical, clinical and economic perspective. This lecture will deliver insight into the aspects to consider during the decision making process to invest in X-ray imaging equipment. Outdated metric still hampers realistic product comparison. It is time to change this and to comply with latest standards, which consider current technology. Failure modes and ways to avoid down-time of the equipment shall be discussed. In view of the increasing number of interventional procedures and the hazards associated with ionizing radiation, toxic contrast agents, and the combination thereof, the aspect of system reliability is of paramount importance. Methods: A comprehensive picture of trends for different modalities (CT, angiography, general radiology) has been drawn and led to the development of novel X-ray tube technology. Results: Recent X-ray tubes feature enhanced reliability and unprecedented performance. Relevant metrics for product comparison still have to be implemented in practice. Conclusion: The speed of scientific and industrial development of new diagnostic and therapeutic X-ray sources remains tremendous. Still, users suffer from gaps between desire and reality in day-to-day diagnostic routine. X-ray sources are still limiting cutting-edge medical procedures. Side-effects of wear and tear, limitations of the clinical work flow, costs, the characteristics of the X-ray spectrum and others topics need to be further addressed. New applications and modalities, like detection-based color-resolved X-ray and phase-contrast / dark-field imaging will impact the course of new developments of X-ray sources. Learning Objectives: Understand the basic requirements on medical diagnostic X-ray sources per modality Learn to select the optimal equipment employing state-of-the-art metric Know causes of failures, depending on the way X-ray sources are operated Understand methods to remediate

TH-F-209-00: Pitfalls: Reliability and Performance of Diagnostic X-Ray Sources

Energy Technology Data Exchange (ETDEWEB)

NONE

2016-06-15

Purpose: Performance and reliability of medical X-ray tubes for imaging are crucial from an ethical, clinical and economic perspective. This lecture will deliver insight into the aspects to consider during the decision making process to invest in X-ray imaging equipment. Outdated metric still hampers realistic product comparison. It is time to change this and to comply with latest standards, which consider current technology. Failure modes and ways to avoid down-time of the equipment shall be discussed. In view of the increasing number of interventional procedures and the hazards associated with ionizing radiation, toxic contrast agents, and the combination thereof, the aspect of system reliability is of paramount importance. Methods: A comprehensive picture of trends for different modalities (CT, angiography, general radiology) has been drawn and led to the development of novel X-ray tube technology. Results: Recent X-ray tubes feature enhanced reliability and unprecedented performance. Relevant metrics for product comparison still have to be implemented in practice. Conclusion: The speed of scientific and industrial development of new diagnostic and therapeutic X-ray sources remains tremendous. Still, users suffer from gaps between desire and reality in day-to-day diagnostic routine. X-ray sources are still limiting cutting-edge medical procedures. Side-effects of wear and tear, limitations of the clinical work flow, costs, the characteristics of the X-ray spectrum and others topics need to be further addressed. New applications and modalities, like detection-based color-resolved X-ray and phase-contrast / dark-field imaging will impact the course of new developments of X-ray sources. Learning Objectives: Understand the basic requirements on medical diagnostic X-ray sources per modality Learn to select the optimal equipment employing state-of-the-art metric Know causes of failures, depending on the way X-ray sources are operated Understand methods to remediate

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

Science.gov (United States)

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

2005-05-01

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

Pump performance and reliability follow-up by the French Safety Authorities

International Nuclear Information System (INIS)

Clausner, J.P.; De La Ronciere, X.; Scott de Martinville, E.; Courbiere, P.

1990-12-01

This paper will present, through actual examples, the methodology of the performance and reliability safety-related pumps evaluation applied by the French Safety Authorities and the lessons drawn from this evaluation

Reliable computation from contextual correlations

Science.gov (United States)

Oestereich, André L.; Galvão, Ernesto F.

2017-12-01

An operational approach to the study of computation based on correlations considers black boxes with one-bit inputs and outputs, controlled by a limited classical computer capable only of performing sums modulo-two. In this setting, it was shown that noncontextual correlations do not provide any extra computational power, while contextual correlations were found to be necessary for the deterministic evaluation of nonlinear Boolean functions. Here we investigate the requirements for reliable computation in this setting; that is, the evaluation of any Boolean function with success probability bounded away from 1 /2 . We show that bipartite CHSH quantum correlations suffice for reliable computation. We also prove that an arbitrarily small violation of a multipartite Greenberger-Horne-Zeilinger noncontextuality inequality also suffices for reliable computation.

Influence of organizational factors on performance reliability

International Nuclear Information System (INIS)

Haber, S.B.; O'Brien, J.N.; Metlay, D.S.; Crouch, D.A.

1991-12-01

This is the first volume of a two-volume report. Volume 2 will be published at a later date. This report presents the results of a research project conducted by Brookhaven National Laboratory for the United States Nuclear Regulatory Commission, Office of Nuclear Regulatory Research. The purpose of the project was to develop a general methodology to be use in the assessment of the organizational factors which affect performance reliability (safety) in a nuclear power plant. The research described in this report includes the development of the Nuclear Organization and Management Analysis Concept (GNOMIC). This concept characterizes the organizational factors that impact safety performance in a nuclear power plant and identifies some methods for systematically measuring and analyzing the influence of these factors on safety performance. This report is divided into two parts; Part 1 presents an overview of the development of the methodology, while Part 2 provides more details and a technical analysis of the methodological development. Specifically, the results of two demonstration studies, the feasibility of the methodology, and a specific applications for which the methodology was developed are presented

The collection, storage and use of equipment performance data for the safety and reliability assessment of nuclear power plants

International Nuclear Information System (INIS)

Fothergill, C.D.H.

1975-01-01

It has been characteristic of the Nuclear Industry that it should grow up in an atmosphere where reliability and operational safety considerations have been of vital importance. Consequently all aspects of Nuclear Power Reactor design, construction and operation (in the U.K.A.E.A.) are subjected to rigorous reliability assessments, beginning with the automatic protective devices and the safety shut-down systems. This has resulted in the setting up of large and small private data stores to support this upsurgence of Safety and Reliability assessment work. Unfortunately, much of the information being stored and published falls short of the minimum requirements of Safety Assessors and Reliability Analysts who need to make use of it. That there is still an urgent need for more work to be done in the Reliability Data field is universally acknowledged. The characteristics which make up good quality reliability data must be defined and achievable minimum standards must be set for its identification, collection, storage and retrieval. To this end the United Kingdom Atomic Energy Authority have set up the Systems Reliability Service Data Bank. This includes a computerized storage facility comprised of two principal data stores: (i) Reliability Data Store, (ii) Event Data Store. The figures available in the Reliability Data Store range from those relating to the lifetimes of minute components to those obtained from the assessment of whole plants and complete assemblies. These data have been accumulated from many reliable sources both inside and outside the Nuclear Industry, including the transfer of 'live' data generated from the results of reliability surveillance exercises associated with Event Data collection. Computer techniques developed specifically for the Reliability Data Store enable further 'processing' of these data to be carried out. The Event Data Store consists of three discrete computerized data stores, each one providing the necessary storage, retrieval and

Survey of methods used to asses human reliability in the human factors reliability benchmark exercise

International Nuclear Information System (INIS)

Poucet, A.

1988-01-01

The Joint Research Centre of the European Commission has organised a Human Factors Reliability Benchmark Exercise (HF-RBE) with the aim to assess the state-of-the-art in human reliability modelling and assessment. Fifteen teams from eleven countries, representing industry, utilities, licensing organisations and research institutes, participate in the HF-RBE, which is organised around two study cases: (1) analysis of routine functional test and maintenance procedures, with the aim to assess the probability of test-induced failures, the probability of failures to remain unrevealed, and the potential to initiate transients because of errors performed in the test; and (2) analysis of human actions during an operational transient, with the aim to assess the probability that the operators will correctly diagnose the malfunctions and take proper corrective action. The paper briefly reports how the HF-RBE was structured and gives an overview of the methods that have been used for predicting human reliability in both study cases. The experience in applying these methods is discussed and the results obtained are compared. (author)

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

International Nuclear Information System (INIS)

Sinha, Purnendu

2011-01-01

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

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

Development of performance model and optimization strategy for standalone operation of CPV-hydrogen system utilizing multi-junction solar cell

KAUST Repository

Burhan, Muhammad; Shahzad, Muhammad Wakil; Ng, Kim Choon

2017-01-01

Despite highest energy potential, solar energy is only available during diurnal period with varying intensity. Therefore, owing to solar intermittency, solar energy systems need to operate in standalone configuration for steady power supply which requires reliable and sustainable energy storage. Hydrogen production has proved to be the most reliable and sustainable energy storage option for medium and long term operation. However, at the first priority, solar energy must be captured with high efficiency, in order to reduce the overall size of the system and energy storage. Multi-junction solar cells (MJCs) provide highest energy efficiency among all of the photovoltaic technologies and the concentrated photovoltaic (CPV) system concept makes their use cost effective. However, literature is lacking the performance model and optimization strategy for standalone operation of the CPV-hydrogen system. In addition, there is no commercial tool available that can analyze CPV performance, utilizing multi-junction solar cell. This paper proposes the performance model for the CPV-hydrogen systems and the multi-objective optimization strategy for its standalone operation and techno-economic analysis, using micro genetic algorithm (micro-GA). The electrolytic hydrogen production with compression storage and fuel cell, is used as energy storage system. The CPV model is verified for the experimental data of InGaP/InGaAs/Ge triple junction solar cell. An optimal CPV system design is provided for uninterrupted power supply, even under seasonal weather variations. Such approach can be easily integrated with commercial tools and the presented performance data can be used for the design of individual components of the system.

Development of performance model and optimization strategy for standalone operation of CPV-hydrogen system utilizing multi-junction solar cell

KAUST Repository

Burhan, Muhammad

2017-09-16

Despite highest energy potential, solar energy is only available during diurnal period with varying intensity. Therefore, owing to solar intermittency, solar energy systems need to operate in standalone configuration for steady power supply which requires reliable and sustainable energy storage. Hydrogen production has proved to be the most reliable and sustainable energy storage option for medium and long term operation. However, at the first priority, solar energy must be captured with high efficiency, in order to reduce the overall size of the system and energy storage. Multi-junction solar cells (MJCs) provide highest energy efficiency among all of the photovoltaic technologies and the concentrated photovoltaic (CPV) system concept makes their use cost effective. However, literature is lacking the performance model and optimization strategy for standalone operation of the CPV-hydrogen system. In addition, there is no commercial tool available that can analyze CPV performance, utilizing multi-junction solar cell. This paper proposes the performance model for the CPV-hydrogen systems and the multi-objective optimization strategy for its standalone operation and techno-economic analysis, using micro genetic algorithm (micro-GA). The electrolytic hydrogen production with compression storage and fuel cell, is used as energy storage system. The CPV model is verified for the experimental data of InGaP/InGaAs/Ge triple junction solar cell. An optimal CPV system design is provided for uninterrupted power supply, even under seasonal weather variations. Such approach can be easily integrated with commercial tools and the presented performance data can be used for the design of individual components of the system.

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

Modeling high-Power Accelerators Reliability-SNS LINAC (SNS-ORNL); MAX LINAC (MYRRHA)

International Nuclear Information System (INIS)

Pitigoi, A. E.; Fernandez Ramos, P.

2013-01-01

Improving reliability has recently become a very important objective in the field of particle accelerators. The particle accelerators in operation are constantly undergoing modifications, and improvements are implemented using new technologies, more reliable components or redundant schemes (to obtain more reliability, strength, more power, etc.) A reliability model of SNS (Spallation Neutron Source) LINAC has been developed within MAX project and analysis of the accelerator systems reliability has been performed within the MAX project, using the Risk Spectrum reliability analysis software. The analysis results have been evaluated by comparison with the SNS operational data. Results and conclusions are presented in this paper, oriented to identify design weaknesses and provide recommendations for improving reliability of MYRRHA linear accelerator. The SNS reliability model developed for the MAX preliminary design phase indicates possible avenues for further investigation that could be needed to improve the reliability of the high-power accelerators, in view of the future reliability targets of ADS accelerators.

A comparison of operational performance : Washington state ferries to ferry operators worldwide.

Science.gov (United States)

2010-06-01

This project compares eight measures of performance related to transit service quality (e.g. trip reliability, on-time departures) and cost-efficiency (e.g. farebox recovery, subsidy per passenger) between Washington State Ferries (WSF) and 23 ferry ...

Reliability issues and solutions for coding social communication performance in classroom settings.

Science.gov (United States)

Olswang, Lesley B; Svensson, Liselotte; Coggins, Truman E; Beilinson, Jill S; Donaldson, Amy L

2006-10-01

To explore the utility of time-interval analysis for documenting the reliability of coding social communication performance of children in classroom settings. Of particular interest was finding a method for determining whether independent observers could reliably judge both occurrence and duration of ongoing behavioral dimensions for describing social communication performance. Four coders participated in this study. They observed and independently coded 6 social communication behavioral dimensions using handheld computers. The dimensions were mutually exclusive and accounted for all verbal and nonverbal productions during a specified time frame. The technology allowed for coding frequency and duration for each entered code. Data were collected from 20 different 2-min video segments of children in kindergarten through 3rd-grade classrooms. Data were analyzed for interobserver and intraobserver agreements using time-interval sorting and Cohen's kappa. Further, interval size and total observation length were manipulated to determine their influence on reliability. The data revealed interval sorting and kappa to be a suitable method for examining reliability of occurrence and duration of ongoing social communication behavioral dimensions. Nearly all comparisons yielded medium to large kappa values; interval size and length of observation minimally affected results. Implications The analysis procedure described in this research solves a challenge in reliability: comparing coding by independent observers of both occurrence and duration of behaviors. Results indicate the utility of a new coding taxonomy and technology for application in online observations of social communication in a classroom setting.

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...

Human reliability analysis using event trees

International Nuclear Information System (INIS)

Heslinga, G.

1983-01-01

The shut-down procedure of a technologically complex installation as a nuclear power plant consists of a lot of human actions, some of which have to be performed several times. The procedure is regarded as a chain of modules of specific actions, some of which are analyzed separately. The analysis is carried out by making a Human Reliability Analysis event tree (HRA event tree) of each action, breaking down each action into small elementary steps. The application of event trees in human reliability analysis implies more difficulties than in the case of technical systems where event trees were mainly used until now. The most important reason is that the operator is able to recover a wrong performance; memory influences play a significant role. In this study these difficulties are dealt with theoretically. The following conclusions can be drawn: (1) in principle event trees may be used in human reliability analysis; (2) although in practice the operator will recover his fault partly, theoretically this can be described as starting the whole event tree again; (3) compact formulas have been derived, by which the probability of reaching a specific failure consequence on passing through the HRA event tree after several times of recovery is to be calculated. (orig.)

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...

Brain performance enhancement for military operators

NARCIS (Netherlands)

Erp, J.B.F.; Reschke, S.; Grootjen, M.; Brouwer, A.-M.

2009-01-01

Performance of military operators depends on both physical and cognitive aspects. Enhancement of operator performance should therefore address both the body and the brain. This paper focuses on the latter. We provide an extended list of areas where neuroscientific knowledge may be important like

76 FR 23801 - North American Electric Reliability Corporation; Order Approving Reliability Standard

Science.gov (United States)

2011-04-28

... have an operating plan and facilities for backup functionality to ensure Bulk-Power System reliability... entity's primary control center on the reliability of the Bulk-Power System. \\1\\ Mandatory Reliability... potential impact of a violation of the Requirement on the reliability of the Bulk-Power System. The...

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

Towards higher reliability of CMS computing facilities

International Nuclear Information System (INIS)

Bagliesi, G; Bloom, K; Brew, C; Flix, J; Kreuzer, P; Sciabà, A

2012-01-01

The CMS experiment has adopted a computing system where resources are distributed worldwide in more than 50 sites. The operation of the system requires a stable and reliable behaviour of the underlying infrastructure. CMS has established procedures to extensively test all relevant aspects of a site and their capability to sustain the various CMS computing workflows at the required scale. The Site Readiness monitoring infrastructure has been instrumental in understanding how the system as a whole was improving towards LHC operations, measuring the reliability of sites when running CMS activities, and providing sites with the information they need to troubleshoot any problem. This contribution reviews the complete automation of the Site Readiness program, with the description of monitoring tools and their inclusion into the Site Status Board (SSB), the performance checks, the use of tools like HammerCloud, and the impact in improving the overall reliability of the Grid from the point of view of the CMS computing system. These results are used by CMS to select good sites to conduct workflows, in order to maximize workflows efficiencies. The performance against these tests seen at the sites during the first years of LHC running is as well reviewed.

Individual Differences in Human Reliability Analysis

Energy Technology Data Exchange (ETDEWEB)

Jeffrey C. Joe; Ronald L. Boring

2014-06-01

While human reliability analysis (HRA) methods include uncertainty in quantification, the nominal model of human error in HRA typically assumes that operator performance does not vary significantly when they are given the same initiating event, indicators, procedures, and training, and that any differences in operator performance are simply aleatory (i.e., random). While this assumption generally holds true when performing routine actions, variability in operator response has been observed in multiple studies, especially in complex situations that go beyond training and procedures. As such, complexity can lead to differences in operator performance (e.g., operator understanding and decision-making). Furthermore, psychological research has shown that there are a number of known antecedents (i.e., attributable causes) that consistently contribute to observable and systematically measurable (i.e., not random) differences in behavior. This paper reviews examples of individual differences taken from operational experience and the psychological literature. The impact of these differences in human behavior and their implications for HRA are then discussed. We propose that individual differences should not be treated as aleatory, but rather as epistemic. Ultimately, by understanding the sources of individual differences, it is possible to remove some epistemic uncertainty from analyses.

Development of a highly reliable CRT processor

International Nuclear Information System (INIS)

Shimizu, Tomoya; Saiki, Akira; Hirai, Kenji; Jota, Masayoshi; Fujii, Mikiya

1996-01-01

Although CRT processors have been employed by the main control board to reduce the operator's workload during monitoring, the control systems are still operated by hardware switches. For further advancement, direct controller operation through a display device is expected. A CRT processor providing direct controller operation must be as reliable as the hardware switches are. The authors are developing a new type of highly reliable CRT processor that enables direct controller operations. In this paper, we discuss the design principles behind a highly reliable CRT processor. The principles are defined by studies of software reliability and of the functional reliability of the monitoring and operation systems. The functional configuration of an advanced CRT processor is also addressed. (author)

Feasibility study for the European Reliability Data System (ERDS)

International Nuclear Information System (INIS)

Mancini, G.

1980-01-01

In the framework of the Reactor Safety Programme of the Commission of the European Communities, the JRC - Ispra Establishment has performed a feasibility study for an integrated European Reliability Data System, the aim of which is the collection and organization of information related to the operation of LWRs with regard to component and systems behaviour, abnormal occurrences, outages, etc. Component Event Data Bank (CEGB), Abnormal Occurrences Reporting System, Generic Reliability Parameter Data Bank, Operating Unit Status Reports and the main activities carried out during the last two years are described. The most important achievements are briefly reported, such as: Reference Classification for Systems, Components and Failure Events, Informatic Structure of the Pilot Experiment of the CEDB, Information Retrieval System for Abnormal Occurrences Reports, Data Bank on Component Reliability Parameters, System on the Exchange of Operation Experience of LWRs, Statistical Data Treatment. Finally, the general conclusions of the feasibility study are summarized: the possibility and the usefulness for the creation of an integrated European Reliability Data System are outlined. (author)

Performing a local barrier operation

Science.gov (United States)

Archer, Charles J; Blocksome, Michael A; Ratterman, Joseph D; Smith, Brian E

2014-03-04

Performing a local barrier operation with parallel tasks executing on a compute node including, for each task: retrieving a present value of a counter; calculating, in dependence upon the present value of the counter and a total number of tasks performing the local barrier operation, a base value, the base value representing the counter's value prior to any task joining the local barrier; calculating, in dependence upon the base value and the total number of tasks performing the local barrier operation, a target value of the counter, the target value representing the counter's value when all tasks have joined the local barrier; joining the local barrier, including atomically incrementing the value of the counter; and repetitively, until the present value of the counter is no less than the target value of the counter: retrieving the present value of the counter and determining whether the present value equals the target value.

Summary of component reliability data for probabilistic safety analysis of Korean standard nuclear power plant

International Nuclear Information System (INIS)

Choi, S. Y.; Han, S. H.

2004-01-01

The reliability data of Korean NPP that reflects the plant specific characteristics is necessary for PSA of Korean nuclear power plants. We have performed a study to develop the component reliability DB and S/W for component reliability analysis. Based on the system, we had have collected the component operation data and failure/repair data during plant operation data to 1998/2000 for YGN 3,4/UCN 3,4 respectively. Recently, we have upgraded the database by collecting additional data by 2002 for Korean standard nuclear power plants and performed component reliability analysis and Bayesian analysis again. In this paper, we supply the summary of component reliability data for probabilistic safety analysis of Korean standard nuclear power plant and describe the plant specific characteristics compared to the generic data

Proving test on the reliability for nuclear valves

International Nuclear Information System (INIS)

Kajiyama, Yasuo; Tashiro, Hisao; Uga, Takeo; Maeda, Shunichi.

1986-01-01

Since valves are the most common components, they could be the most frequent causes of troubles in nuclear power plants. This proving test, therefore, has an important meaning to examine and verify the reliability of various valves under simulating conditions of abnormal and transient operations of the nuclear power plant. The test was performed mainly for the various types and pressure ratings of valves which were used in the primary and secondary systems in BWR and PWR nuclear power plants and which had major operating or safety related functions in those nuclear power plants. The results of the proving test, confirmed for more than four years, showed relatively favourable performance of the tested valves. It is concluded that performances of valves including operability, seat sealing and structural integrity were proved under the thermal cycling, vibration and pipe reaction load conditions. Operating functions during and after accident such as loss of coolant accident were satisfactory. From these results, it was considered that the purpose of this proving test was satisfactorily fulfilled. Several data accumulated by the test would be useful to get better reliability if it was evaluated with the actually experienced data of valves in the nuclear power plants. (Nogami, K.)

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

Science.gov (United States)

Ha, Taesung

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

Operating systems

CERN Document Server

Tsichritzis, Dionysios C; Rheinboldt, Werner

1974-01-01

Operating Systems deals with the fundamental concepts and principles that govern the behavior of operating systems. Many issues regarding the structure of operating systems, including the problems of managing processes, processors, and memory, are examined. Various aspects of operating systems are also discussed, from input-output and files to security, protection, reliability, design methods, performance evaluation, and implementation methods.Comprised of 10 chapters, this volume begins with an overview of what constitutes an operating system, followed by a discussion on the definition and pr

Thermal Performance and Reliability Analysis of Single-Phase PV Inverters with Reactive Power Injection Outside Feed-In Operating Hours

DEFF Research Database (Denmark)

Anurag, Anup; Yang, Yongheng; Blaabjerg, Frede

2015-01-01

Reactive power support by photovoltaic (PV) systems is of increasingly interest, when compared to the conventional reactive power compensation devices. PV inverters can exchange reactive power with the utility grid in a decentralized manner even outside feed-in operation, especially at nights when...... there is no solar irradiance. However, reactive power injection causes additional power losses in the switching components leading to a temperature rise in the devices. Thus, this paper analyses the impact of reactive power injection by PV inverters outside feed-in operation on the thermal performance...... of their power switching components. A thermal analysis based on the mission profile (i.e., solar irradiance and ambient temperature) has been incorporated, so as to determine the additional temperature rise in the components induced by the operation outside feed-in hours. An analytical lifetime model has been...

Assessing segment- and corridor-based travel-time reliability on urban freeways : final report.

Science.gov (United States)

2016-09-01

Travel time and its reliability are intuitive performance measures for freeway traffic operations. The objective of this project was to quantify segment-based and corridor-based travel time reliability measures on urban freeways. To achieve this obje...

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)

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)

Preventive maintenance and reliability-centered maintenance

International Nuclear Information System (INIS)

Anderson, J.G.

1989-01-01

In the recent past, the primary function of the preventive maintenance program at a nuclear power plant was to maintain the operability and reliability of the plant. Reducing overall maintenance costs by performing effective preventive maintenance, instead of more costly and disruptive corrective maintenance, instead of more costly and disruptive corrective maintenance, was a secondary consideration. In today's operating environment, the preventive maintenance program must meet the test of cost-effectiveness as well as many new standards for performance that are being required by rate regulators. The preventive maintenance program must be able to withstand the challenge of independent audit to a new standard of technical adequacy and compliance with recommendations from component vendors. In this new environment, the standard that is being applied at the San Onofre nuclear generating station (SONGS) is that the preventive maintenance program must meet the test of cost-effectiveness, improve equipment performance, support increased plant availability, and (a) literally implement the recommendations of the vendor, (b) provide other compensation for the vendor recommendation, or (c) provide technical justification for the deviation. The subject of this paper is the way that reliability-centered maintenance (RCM) is helping SONGS meet these challenges

Reliability assessment of passive isolation condenser system of AHWR using APSRA methodology

International Nuclear Information System (INIS)

Nayak, A.K.; Jain, Vikas; Gartia, M.R.; Prasad, Hari; Anthony, A.; Bhatia, S.K.; Sinha, R.K.

2009-01-01

In this paper, a methodology known as APSRA (Assessment of Passive System ReliAbility) is used for evaluation of reliability of passive isolation condenser system of the Indian Advanced Heavy Water Reactor (AHWR). As per the APSRA methodology, the passive system reliability evaluation is based on the failure probability of the system to perform the design basis function. The methodology first determines the operational characteristics of the system and the failure conditions based on a predetermined failure criterion. The parameters that could degrade the system performance are identified and considered for analysis. Different modes of failure and their cause are identified. The failure surface is predicted using a best estimate code considering deviations of the operating parameters from their nominal states, which affect the isolation condenser system performance. Once the failure surface of the system is predicted, the causes of failure are examined through root diagnosis, which occur mainly due to failure of mechanical components. Reliability of the system is evaluated through a classical PSA treatment based on the failure probability of the components using generic data

Comparison of reading performance tests concerning difficulty of sentences and paragraphs and their reliability

NARCIS (Netherlands)

Brussee, T.; van Nispen, R.M.A.; Klerkx, E.M.F.J.; Knol, D.L.; van Rens, G.H.M.B.

2015-01-01

In research and practice, sentences or paragraphs of reading tests may be randomly chosen to assess reading performance. This means that in addition to test reliability, all sentences or paragraphs should be reliable and equally difficult to read. The sentences and paragraphs of five (un-)

Exploitation examination of reliability of coal dust systems

International Nuclear Information System (INIS)

Dojchinovski, Ilija; Trajkovski, Kole

1997-01-01

Designers and operators wish is, long, failure free operation at designed parameters of every system. Always we know the system start up time, but we don't know how long this system will operate successfully. Because of that in this article is given a method how, step by step, to determine the reliability of the system. Reliability parameters are obtained from experimental and operational data. When reliability parameters are determined then it is very easy to compare reliability of similar systems, for example excavators, or different systems, such as truck and rubber band transport system. Practical use of the theory of reliability is by purchasing of the systems when manufacturers have to have and present reliability parameters and on this way we can decide which system satisfies our needs regarding the quality-price-reliability. Reliability can be practically used in system operation where: 1) system reliability is maintained with proper start, use and shutdown of the system; 2) a system reliability is maintained with good maintenance organization; 3) a system reliability is maintained with innovations and improvements with final purpose removing of the imperfections experienced through the operation. Reliability is very important parameter in power generation plants. (Author)

Reliability of software

International Nuclear Information System (INIS)

Kopetz, H.

1980-01-01

Common factors and differences in the reliability of hardware and software; reliability increase by means of methods of software redundancy. Maintenance of software for long term operating behavior. (HP) [de

Evaluating operator performance on full-scope simulators: A pragmatic approach to an intractable measurement problem

International Nuclear Information System (INIS)

Fuld, R.

1989-01-01

Industry trends toward full-scope, plant-referenced control room simulators have accelerated. The cost of such training is high, but the cost of training ineffectiveness is even higher if it permits serious errors or operator disqualification to occur. Effective measures of operator performance are needed, but the complexity of the task environment and the many aspects of and requirements for operator performance conspire to make such measurement a challenging problem. Combustion Engineering (C-E) Owners' Group task No. 572 was undertaken to develop a tractable and effective methodology for evaluating team performance in a requalification context on full-scope simulator scenarios. The following concepts were pursued as design goals for the method: 1. validity; 2. sensitivity; 3. reliability; 4. usability. In addition, the resulting approach was to meet the requirements of ES-601, Implementation Guidance of the NRC for Administration of Requalifying Exams. A survey of existing evaluation tools and techniques was made to determine the strengths and weaknesses of each. Based on those findings, a multimethod approach was developed drawing on the combined strengths of several general methods. The paper discusses procedural milestones, comments as subjective ratings, failure criteria, and tracked plant parameters

Human factors reliability Benchmark exercise

International Nuclear Information System (INIS)

Poucet, A.

1989-06-01

The Joint Research Centre of the European Commission has organized a Human Factors Reliability Benchmark Exercise (HF-RBE) with the aim of assessing the state of the art in human reliability modelling and assessment. Fifteen teams from eleven countries, representing industry, utilities, licensing organisations and research institutes, participated in the HF-RBE. The HF-RBE was organized around two study cases: (1) analysis of routine functional Test and Maintenance (T and M) procedures: with the aim of assessing the probability of test induced failures, the probability of failures to remain unrevealed and the potential to initiate transients because of errors performed in the test; (2) analysis of human actions during an operational transient: with the aim of assessing the probability that the operators will correctly diagnose the malfunctions and take proper corrective action. This report contains the final summary reports produced by the participants in the exercise

Reliability of performance velocity for jump squats under feedback and nonfeedback conditions.

Science.gov (United States)

Randell, Aaron D; Cronin, John B; Keogh, Justin Wl; Gill, Nicholas D; Pedersen, Murray C

2011-12-01

Randell, AD, Cronin, JB, Keogh, JWL, Gill, ND, and Pedersen, MC. Reliability of performance velocity for jump squats under feedback and nonfeedback conditions. J Strength Cond Res 25(12): 3514-3518, 2011-Advancements in the monitoring of kinematic and kinetic variables during resistance training have resulted in the ability to continuously monitor performance and provide feedback during training. If equipment and software can provide reliable instantaneous feedback related to the variable of interest during training, it is thought that this may result in goal-oriented movement tasks that increase the likelihood of transference to on-field performance or at the very least improve the mechanical variable of interest. The purpose of this study was to determine the reliability of performance velocity for jump squats under feedback and nonfeedback conditions over 3 consecutive training sessions. Twenty subjects were randomly allocated to a feedback or nonfeedback group, and each group performed a total of 3 "jump squat" training sessions with the velocity of each repetition measured using a linear position transducer. There was less change in mean velocities between sessions 1-2 and sessions 2-3 (0.07 and 0.02 vs. 0.13 and -0.04 m·s), less random variation (TE = 0.06 and 0.06 vs. 0.10 and 0.07 m·s) and greater consistency (intraclass correlation coefficient = 0.83 and 0.87 vs. 0.53 and 0.74) between sessions for the feedback condition as compared to the nonfeedback condition. It was concluded that there is approximately a 50-50 probability that the provision of feedback was beneficial to the performance in the squat jump over multiple sessions. It is suggested that this has the potential for increasing transference to on-field performance or at the very least improving the mechanical variable of interest.

Operator Actions Within a Safety Instrumented Function

International Nuclear Information System (INIS)

Suttinger, L.T.

2002-01-01

This paper presents an overview of the factors that should be considered when crediting operator action for performing a safety function or being a part of the process of enabling a safety function. Criteria for evaluating operator action, such as required time response and operator training among others, are discussed. The paper will address these and other factors that should be considered when determining the reliability of the operator to respond and perform his/her part of the safety function. The entire safety function includes the operator and the reliability of the instrumented system that provides the alarm or indication, the final control element, and support systems. The integration of the operator performance with the hardware safety availability, including the effects of the supporting systems is discussed. The analysis of these factors will provide the justification for the amount of risk reduction or safety integrity level that can be credited for the Safety Instrumented Function (SIF), including operator action

Reliability estimation for check valves and other components

International Nuclear Information System (INIS)

McElhaney, K.L.; Staunton, R.H.

1996-01-01

For years the nuclear industry has depended upon component operational reliability information compiled from reliability handbooks and other generic sources as well as private databases generated by recognized experts both within and outside the nuclear industry. Regrettably, these technical bases lacked the benefit of large-scale operational data and comprehensive data verification, and did not take into account the parameters and combinations of parameters that affect the determination of failure rates. This paper briefly examines the historic use of generic component reliability data, its sources, and its limitations. The concept of using a single failure rate for a particular component type is also examined. Particular emphasis is placed on check valves due to the information available on those components. The Appendix presents some of the results of the extensive analyses done by Oak Ridge National Laboratory (ORNL) on check valve performance

Transparent reliability model for fault-tolerant safety systems

International Nuclear Information System (INIS)

Bodsberg, Lars; Hokstad, Per

1997-01-01

A reliability model is presented which may serve as a tool for identification of cost-effective configurations and operating philosophies of computer-based process safety systems. The main merit of the model is the explicit relationship in the mathematical formulas between failure cause and the means used to improve system reliability such as self-test, redundancy, preventive maintenance and corrective maintenance. A component failure taxonomy has been developed which allows the analyst to treat hardware failures, human failures, and software failures of automatic systems in an integrated manner. Furthermore, the taxonomy distinguishes between failures due to excessive environmental stresses and failures initiated by humans during engineering and operation. Attention has been given to develop a transparent model which provides predictions which are in good agreement with observed system performance, and which is applicable for non-experts in the field of reliability

On Bayesian System Reliability Analysis

Energy Technology Data Exchange (ETDEWEB)

Soerensen Ringi, M

1995-05-01

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

On Bayesian System Reliability Analysis

International Nuclear Information System (INIS)

Soerensen Ringi, M.

1995-01-01

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

FFTF [Fast Flux Test Facility] reactor shutdown system reliability reevaluation

International Nuclear Information System (INIS)

Pierce, B.F.

1986-07-01

The reliability analysis of the Fast Flux Test Facility reactor shutdown system was reevaluated. Failure information based on five years of plant operating experience was used to verify original reliability numbers or to establish new ones. Also, system modifications made subsequent to performance of the original analysis were incorporated into the reevaluation. Reliability calculations and sensitivity analyses were performed using a commercially available spreadsheet on a personal computer. The spreadsheet was configured so that future failures could be tracked and compared with expected failures. A number of recommendations resulted from the reevaluation including both increased and decreased surveillance intervals. All recommendations were based on meeting or exceeding existing reliability goals. Considerable cost savings will be incurred upon implementation of the recommendations

The Effect of Degraded Digital Instrumentation and Control systems on Human-system Interfaces and Operator Performance

International Nuclear Information System (INIS)

O'Hara, J.M.; Gunther, B.; Martinez-Guridi, G.; Xing, J.; Barnes, V.

2010-01-01

Integrated digital instrumentation and control (I and C) systems in new and advanced nuclear power plants (NPPs) will support operators in monitoring and controlling the plants. Even though digital systems typically are expected to be reliable, their potential for degradation or failure significantly could affect the operators performance and, consequently, jeopardize plant safety. This U.S. Nuclear Regulatory Commission (NRC) research investigated the effects of degraded I and C systems on human performance and on plant operations. The objective was to develop technical basis and guidance for human factors engineering (HFE) reviews addressing the operator's ability to detect and manage degraded digital I and C conditions. We reviewed pertinent standards and guidelines, empirical studies, and plant operating experience. In addition, we evaluated the potential effects of selected failure modes of the digital feedwater control system of a currently operating pressurized water reactor (PWR) on human-system interfaces (HSIs) and the operators performance. Our findings indicated that I and C degradations are prevalent in plants employing digital systems, and the overall effects on the plant's behavior can be significant, such as causing a reactor trip or equipment to operate unexpectedly. I and C degradations may affect the HSIs used by operators to monitor and control the plant. For example, deterioration of the sensors can complicate the operators interpretation of displays, and sometimes may mislead them by making it appear that a process disturbance has occurred. We used the findings as the technical basis upon which to develop HFE review guidance.

Research about reactor operator's personality characteristics and performance

International Nuclear Information System (INIS)

Wei Li; He Xuhong; Zhao Bingquan

2003-01-01

To predict and evaluate the reactor operator's performance by personality characteristics is an important part of reactor operator safety assessment. Using related psychological theory combined with the Chinese operator's fact and considering the effect of environmental factors to personality analysis, paper does the research about the about the relationships between reactor operator's performance and personality characteristics, and offers the reference for operator's selection, using and performance in the future. (author)

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.